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Title: Nature's Teachings - Human Invention Anticipated by Nature
Author: Wood, J. G. (John George)
Language: English
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NATURE’S TEACHINGS
[Illustration: The Home]
NATURE’S TEACHINGS
_HUMAN INVENTION
ANTICIPATED BY NATURE_
BY THE LATE
REV. J. G. WOOD, M.A., F.L.S., ETC.
AUTHOR OF “HOMES WITHOUT HANDS,”
“MAN AND BEAST, HERE AND HEREAFTER,” ETC.
_NEW AND REVISED EDITION_
LONDON
J. S. VIRTUE & CO., LIMITED, 26, IVY LANE
PATERNOSTER ROW
LONDON:
PRINTED BY J. S. VIRTUE AND CO., LIMITED.
CITY ROAD.
PREFACE.
A glance at almost any page of this work will denote its object. It is
to show the close connection between Nature and human inventions, and
that there is scarcely an invention of man that has not its prototype in
Nature. And it is worthy of notice that the greatest results have been
obtained from means apparently the most insignificant.
There are two inventions, for example, which have changed the face of
the earth, and which yet sprang from sources that were despised by men,
and thought only fit for the passing sport of childhood. I allude, of
course, to Steam and Electricity, both of which had been child’s toys
for centuries before the one gave us the fixed engine, the locomotive,
and the steamboat, and the other supplied us with the compass and the
electric telegraph.
In the course of this work I have placed side by side a great number of
parallels of Nature and Art, making the descriptions as terse and simple
as possible, and illustrating them with more than seven hundred and
fifty figures. The corollary which I hope will be drawn from the work is
evident enough. It is, that as existing human inventions have been
anticipated by Nature, so it will surely be found that in Nature lie the
prototypes of inventions not yet revealed to man. The great discoverers
of the future will, therefore, be those who will look to Nature for
Art, Science, or Mechanics, instead of taking pride in some new
invention, and then finding that it has existed in Nature for countless
centuries.
I ought to mention that the illustrations are not intended to be
finished drawings, but merely charts or maps, calling attention to the
salient points.
CONTENTS.
NAUTICAL.
CHAP. PAGE
I. THE RAFT 1
II. THE OAR, THE PADDLE, AND THE SCREW 12
III. SUBSIDIARY APPLIANCES.--PART I. 23
IV. SUBSIDIARY APPLIANCES.--PART II. 34
V. SUBSIDIARY APPLIANCES.--PART III.--THE BOAT-HOOK AND
PUNT-POLE.--THE LIFE-BUOY AND PONTOON-RAFT 44
WAR AND HUNTING.
I. THE PITFALL, THE CLUB, THE SWORD, THE SPEAR AND DAGGER 50
II. POISON, ANIMAL AND VEGETABLE.--PRINCIPLE OF THE BARB 62
III. PROJECTILE WEAPONS AND THE SHEATH 74
IV. THE NET 85
V. REVERTED SPIKES 102
VI. THE HOOK.--DEFENSIVE ARMOUR.--THE FORT 115
VII. SCALING INSTRUMENTS.--DEFENCE OF FORT.--IMITATION.--THE
FALL-TRAP 132
VIII. CONCEALMENT.--DISGUISE.--THE TRENCH.--POWER OF
GRAVITY.--MISCELLANEA 144
ARCHITECTURE.
I. THE HUT, TROPIC AND POLAR.--PILLARS AND FLOORING.--TUNNEL
ENTRANCE OF THE IGLOO.--DOORS AND HINGES.--SELF-CLOSING
TRAP-DOORS 159
II. WALLS, DOUBLE AND SINGLE.--PORCHES, EAVES, AND WINDOWS.--THATCH,
SLATES, AND TILES 177
III. THE WINDOW.--GIRDERS, TIES, AND BUTTRESSES.--THE TUNNEL.--THE
SUSPENSION-BRIDGE 190
IV. LIGHTHOUSES.--THE DOVETAIL.--THE DAM.--SUBTERRANEAN
DWELLINGS.--THE PYRAMIDS.--MORTAR, PAINT, AND VARNISH 207
TOOLS
I. THE DIGGING-STICK.--SPADE.--SHEARS AND SCISSORS.--CHISEL
AND ADZE.--THE PLANE AND SPOKESHAVE 222
II. THE SAW AND ITS VARIETIES 239
III. BORING TOOLS.--STRIKING TOOLS.--GRASPING TOOLS 249
IV. POLISHING TOOLS.--MEASURING TOOLS 263
OPTICS.
I. THE MISSIONS OF HISTORY.--THE CAMERA OBSCURA.--LONG
AND SHORT SIGHT.--STEREOSCOPE AND PSEUDOSCOPE.--MULTIPLYING-GLASSES 276
II. THE WATER-TELESCOPE.--IRIS OF THE EYE.--MAGIC LANTERN.--THE
SPECTROSCOPE.--THE THAUMATROPE 291
USEFUL ARTS.
I. PRIMITIVE MAN AND HIS NEEDS.--EARTHENWARE.--BALL-AND-SOCKET
JOINT.--TOGGLE OR KNEE JOINT 308
II. CRUSHING INSTRUMENTS.--THE NUT-CRACKERS, ROLLING-MILL,
AND GRINDSTONE.--PRESSURE OF ATMOSPHERE.--SEED DIBBLES
AND DRILLS 320
III. CLOTH-DRESSING.--BRUSHES AND COMBS.--BUTTONS, HOOKS AND
EYES, AND CLASP 339
IV. THE STOPPER, OR CORK.--THE FILTER 350
V. THE PRINCIPLE OF THE SPRING.--THE ELASTIC SPRING.--ACCUMULATORS.--THE
SPIRAL SPRING 360
VI. SPIRAL AND RINGED TISSUES.--VARIOUS SPRINGS IN NATURE
AND ART 375
VII. FOOD AND COMFORT 390
VIII. DOMESTIC COMFORT 400
IX. ARTIFICIAL WARMTH.--RING AND STAPLE.--THE FAN 412
X. WATER, AND MEANS OF PROCURING IT 422
XI. AËROSTATICS.--WEIGHT OF AIR.--EXPANSION BY HEAT 436
XII. DITTO CONTINUED 447
XIII. TELESCOPIC TUBES.--DIRECT ACTION.--DISTRIBUTION OF
WEIGHT.--TREE-CLIMBING.--THE WHEEL 460
XIV. PAPER AND MOULDING 472
XV. ELECTRICITY AND GALVANISM 482
XVI. TILLAGE.--DRAINAGE.--SPIRAL PRINCIPLE.--CENTRIFUGAL FORCE 492
XVII. OSCILLATION.--UNITED STRENGTH.--THE DOME 504
ACOUSTICS.
I. PERCUSSION.--THE STRING AND REED.--THE
TRUMPET.--EAR-TRUMPET.--STETHOSCOPE 513
NAUTICAL.
CHAPTER I.
Poetry and Science.--The Paper Nautilus and the Sail.--Montgomery’s
“Pelican Island.”--The Nautilus replaced by the Velella.--The
Sailing Raft of Nature and Art.--Description of a Velella Fleet off
Tenby.--The Natural Raft and its Sail.--The Boats of Nature and
Art.--Man’s first Idea of a Boat.--The Kruman’s Canoe and the
_Great Eastern_.--Gradual Development of the Boat.--The Outrigger
Canoe a Mixture of Raft and Boat.--Natural Boats.--The
Water-snails.--The Sea-anemones.--The Egg-boat of the Gnat.--The
Skin-boat of the same Insect.--Shape and Properties of the
Life-boat anticipated in Nature.--Natural Boat of the Stratiomys.
THE RAFT.
It has been frequently said that the modern developments of science are
gradually destroying many of the poetical elements of our daily lives,
and in consequence are reducing us to a dead level of prosaic
commonplace, in which existence is scarcely worth having. The first part
of this rather sweeping assertion is perfectly true, but, as we shall
presently see, the second portion is absolutely untrue.
Science has certainly destroyed, and is destroying, many of the poetic
fancies which made a part of daily life. It must have been a
considerable shock to the mind of an ancient philosopher when he found
himself deprived of the semi-spiritual, semi-human beings with which the
earth and water were thought to be peopled. And even in our own time and
country there is in many places a still lingering belief in the
existence of good and bad fairies inhabiting lake, wood, and glen, the
successors of the Naiads and Dryads, the Fauns and Satyrs, of the former
time. Many persons will doubtless be surprised, even in these days, to
hear that the dreaded Maelström is quite as fabulous as the Symplegades
or Scylla and Charybdis, and that the well-known tale of Edgar Poe is
absolutely without foundation.
Perhaps one of the prettiest legends in natural history is that of the
Paper Nautilus, with which so much poetry is associated. We have all
been accustomed from childhood to Pope’s well-known lines beginning--
“Learn of the little Nautilus to sail,”
and some of us may be acquainted with those graceful verses of James
Montgomery, in his “Pelican Island:”--
“Light as a flake of foam upon the wind,
Keel upward, from the deep emerged a shell,
Shaped like the moon ere half her horn is filled.
Fraught with young life it righted as it rose,
And moved at will along the yielding water.
The native pilot of this little bark
Put out a tier of oars on either side,
Spread to the wafting breeze a two-fold sail,
And mounted up and glided down the billow
In happy freedom, pleased to feel the air,
And wander in the luxury of light.
* * * * *
It closed, sank, dwindled to a point, then nothing,
While the last bubble crowned the dimpling eddy
Through which mine eye still giddily pursued it.”
So deeply ingrained is the poetical notion of the sailing powers
attributed to the nautilus, that many people are quite incredulous when
they are told that there is just as much likelihood of seeing a mermaid
curl her hair as of witnessing a nautilus under sail. How the creature
in question does propel itself will be described in the course of the
present chapter; and the reader will see that although one parallel
between Nature and Art in the nautilus does not exist, there are several
others which until later days have not even been suspected.
It is, therefore, partially true that science does destroy romance. But,
though she destroys, she creates, and she gives infinitely more than she
takes away, as is shown in the many late discoveries which have
transformed the whole system of civilised life. Sometimes, as in the
present instance, she discovers one analogy while destroying another,
and though she shatters the legend of the sailing nautilus, she produces
a marine animal which really does sail, and does not appear to be able
to do anything else. This is the VELELLA, a figure of which, taken from
a specimen in my collection, is given in the illustration, and drawn of
the natural size.
It is one of that vast army of marine creatures known familiarly by the
name of “jelly-fishes,” just as lobsters, crabs, shrimps, oysters,
whelks, periwinkles, and the like, are lumped together under the title
of “shell-fish.” As a rule, these creatures are soft, gelatinous, and,
in fact, are very little more than sea-water entangled in the finest
imaginable mesh-work of animal matter; so fine, indeed, that scarcely
any definite organs can be discovered. The Velella, however, is
remarkable for having a sort of skeleton, if it may be so called,
consisting of two very thin and horny plates, disposed, as shown in the
illustration, so as to form an exact imitation (or perhaps I should say
a precursor) of a raft propelled by a sail. Indeed, the Latin name
Velella signifies a little sail.
[Illustration: VELELLA (NATURAL SIZE).]
[Illustration: SAILING RAFT.]
How well deserved is the name may be seen by the following graphic
account of a Velella fleet sent to me by a lady who takes great interest
in practical zoology:--
“The specimens which I send came from Tenby, a very rough sea having
driven a large living fleet of them on that coast.
“When in life, they are semi-transparent, and radiant in many
rainbow-tinted colours. They came floating towards me in all their
fragile beauty on the rough sea waves. I succeeded in capturing some of
them, and preserved the only portion available for my collection.
“They are extremely tender, and by no means with which I am acquainted
can be preserved more than these skeleton-like cartilaginous plates.
They soon dissolve in either spirits of wine or water, and lose every
vestige of their shape and substance. The upright, thin, pellucid plate
has the appearance of a fairy-like miniature sail, and apparently acted
as such when the creature was floating with its long and many-tinted
tentacles pendent from its lower surface.
“Although widely distributed, they are seldom seen on our own coast,
although sometimes driven there from the warmer regions by stress of
wind and waves.
“These little creatures had never before been seen at Tenby, but when I
asked a native bathing-woman whether she knew their name, she
immediately replied, ‘Sea-butterflies.’ Although the name was evidently
of her own invention, it was most appropriate and poetical. I have
always found the Welsh people abound more than any other nation in
pretty and characteristic synonyms.”[A]
[A] By sailors the Velella is popularly known by the name of
“Sally-man;” _i.e._ Sallee-man.
In answer to a letter in which I asked the writer for some further
information concerning the Velella, sending also an outline sketch of
the animal, which I asked the writer to fill in with the proper colours,
I received the following reply:--
“I will do my best to answer your questions, and to give you what
information I can concerning the creatures.
“When seen at Tenby, they were all floating on the surface of the sea,
the tentacles only being submerged. My specimens floated for a very
short time after capture, death following so quickly that I was obliged
to set to work at once with camel’s-hair brush and penknife to take away
the gelatinous part. Indeed, decomposition took place so rapidly, that
Velellas and myself were simultaneously threatened with extermination.
“Both raft and sail were equally enveloped in a soft, gelatinous
covering, certainly not more than the sixteenth of an inch in thickness,
except under the centre of the raft, where it became slightly thicker.
The covering of the sail was exceedingly thin, and like a transparent
and almost invisible soft skin. The sail is very firmly attached to the
raft, as they did not separate when decomposition began.
“The tentacles were entirely composed of the same soft, jelly-like
substance as that of the envelope, and every part was iridescent in a
sort of vapoury transparent cloud of many-tinted colours, blue and pale
crimson predominating. I have filled up to the best of my memory the
little sketch, and only wish you could have seen the Velellas as I did,
in their full life and beauty.”
Two of the specimens here mentioned are in my collection, and beautiful
little things they are. The two plates are not thicker than ordinary
silver paper, but are wonderfully strong, tough, and elastic. The oval
horizontal plate, or raft, if it may be so called, is strengthened by
being corrugated in concentric lines, and having a multitude of very
fine ribs radiating from the centre to the circumference. It is slightly
thickened on the edges, evidently for the attachment of the tentacles.
The perpendicular plate, or sail, does not occupy the larger diameter of
the raft, but stretches across it diagonally from edge to edge, rising
highest in the centre and diminishing towards the edges, so that it
presents an outline singularly like that of a lateen sail. It is rather
curious that the magnifying glass gives but little, if any, assistance
to the observer, the naked eye answering every purpose. Even the
microscope is useless, detecting no peculiarity of structure. I tried it
with the polariscope, scarcely expecting, but rather hoping, to find
that it was sensitive to polarised light. But no such result took place,
the Velella being quite unaffected by it.
The corresponding illustration is a sketch of a raft to which a sail is
attached. Such rafts as this are in use in many parts of the world, the
sail saving manual labour, and the large steering oar answering the
double purpose of keel and rudder. In the Velella, the tentacles, though
they may not act in the latter capacity, certainly do act in that of the
former, and serve to prevent the little creature from being capsized in
a gale of wind.
THE BOAT.
There is no doubt that the first idea of locomotion in the water,
independently of swimming, was the raft; nor is it difficult to trace
the gradual development of the raft into a Boat. The development of the
Kruman’s canoe into the _Great Eastern_, or a modern ironclad vessel, is
simply a matter of time.
It is tolerably evident that the first raft was nothing more than a
tree-trunk. Finding that the single trunk was apt to turn over with the
weight of the occupant, the next move was evidently to lash two trunks
side by side.
Next would come the great advance of putting the trunks at some distance
apart, and connecting them with cross-bars. This plan would obviate even
the chance of the upsetting of the raft, and it still survives in that
curious mixture of the raft and canoe, the outrigger boat of the
Polynesians, which no gale of wind can upset. It may be torn to pieces
by the storm, but nothing can capsize it as long as it holds together.
Laying a number of smaller logs or branches upon the bars which connect
the larger logs is an evident mode of forming a continuous platform, and
thus the raft is completed. It would not be long before the superior
buoyancy of a hollow over a solid log would be discovered, and so, when
the savage could not find a log ready hollowed to his hand, he would
hollow one for himself, mostly using fire in lieu of tools. The progress
from a hollowed log, or “dug-out,” as it is popularly called, to the
bark canoe, and then the built boat, naturally followed, the boats
increasing in size until they were developed into ships.
Such, then, is a slight sketch of the gradual construction of the Boat,
based, though perhaps ignorantly, on the theory of displacement. Now,
let us ask ourselves whether, in creation, there are any natural boats
which existed before man came upon the earth, and from which he might
have taken the idea if he had been able to reason on the subject. The
Paper Nautilus is, of course, the first example that comes before the
mind; but although, as we have seen, the delicate shell of the nautilus
is not used as a boat, and its sailing and rowing powers are alike
fabulous, there is, as is the case with most fables, a substratum of
truth, and there are aquatic molluscs which form themselves into boats,
although they do not propel themselves with sails or oars.
Many species of molluscs possess this art, but we will select one as an
example of them all, because it is very plentiful in our own country,
and may be found in almost any number. It is the common WATER-SNAIL
(_Limnæa stagnalis_), which abounds in our streams where the current is
not very strong. Even in tolerably swift streams the Limnæa may be found
plentifully in any bay or sudden curve where a reverse current is
generated, and therefore the force of the stream is partially
neutralised. These molluscs absolutely swarm in the Cherwell, and in the
multitudinous ditches which drain the flat country about Oxford into
that river as well as the Isis.
Belonging to the Gasteropods, the Water-snail can crawl over the stones
or aquatic vegetation, just as the common garden snail or slug does on
land. But it has another mode of progression, which it very often
employs in warm weather. It ascends to the surface of the water,
reverses its position so that the shell is downward, spreads out the
foot as widely as possible, and then contracts it in the centre, so as
to form it into a shallow boat.
[Illustration: GNAT-EGG BOAT AND THREE EGGS.]
[Illustration: “DUG-OUT” BOAT OF VARIOUS PARTS OF THE WORLD.]
[Illustration: SEA-ANEMONE ACTING AS BOAT.]
[Illustration: WATER-SNAIL ACTING AS BOAT.]
[Illustration: BIRCH-BARK CANOE.]
[Illustration: PUPA SKIN OF GNAT ACTING AS BOAT.]
The carrying capacity of this boat is necessarily small, but as the
shell and nearly the whole of the animal are submerged, and therefore
mostly sustained by the water, a very small amount of flotative power is
sufficient for the purpose. Sometimes, on a fine day, whole fleets of
these natural boats may be seen floating down the stream, thus obtaining
a change of locality without any personal exertion.
In perfectly still water, where no current can waft the Limnæa on its
easy voyage, it still is able to convey itself from one place to
another. By means of extending and contracting the foot, it actually
contrives to crawl along the surface of the water almost as readily as
if it were upon the under side of some solid body, and, although its
progress is slow, it is very steady. Another very common British
water-snail, the Pouch-shell (_Physa fontinalis_), has almost exactly
the same habits. Reference will be made to the Pouch-shell on another
page.
The capacity for converting the body into a boat is not confined to the
molluscs, but is shared by many other animals. Take, for example, the
well-known marine animals, called popularly SEA-ANEMONES. As they appear
when planted on the rocks, they look as incapable of motion as the
flowers whose names they bear. Yet, by means of the flattened base,
which they use just as a snail uses its feet, they can manage to glide
along the rocks in any direction, though very slowly.
The base is capable of extension and contraction, and by elongating one
side of it, fixing the elongated portion, and then raising the remainder
of the base towards it, the animal makes practically a series of very
slow steps. This mode of progression may often be seen in operation on
the glass front of an aquarium.
The same property of expansion and contraction enables the Sea-anemones
to convert their bodies into boats, and float on the surface of the
water. When one of these animals wishes to swim, it ascends the object
to which it is clinging--say the glass of the aquarium--until it has
reached the air. It then very slowly, and bit by bit, detaches the upper
part of the base from the glass, allowing itself to hang with its
tentacles downward. These, by the way, are almost wholly withdrawn when
the animal is engaged in this business. By degrees the whole of the base
is detached from the glass except a very tiny portion of the edge. The
base is next contracted in the middle into the form of a shallow cup,
and, when this is done, the last hold of the glass is released, and the
animal floats away, supported by its hollowed base.
Entomologists are familiar with the following facts, and were this work
addressed to them alone, a simple mention of the insect would be
sufficient. But as this work is intended for the general public, it will
be necessary to give a description, though a brief one, of the wonderful
manner in which an insect, which we are apt to think is only too common,
plays the part of a boat at its entrance to life and just before its
departure from this world, not to mention its intermediate state, to
which reference will be made under another heading.
The insect in question is the common GNAT (_Culex pipiens_), which makes
such ravages upon those who are afflicted, like myself, with delicate
skins, and can have a limb rendered useless for days by a single
gnat-bite.
In this insect, the beginning and the end of life are so closely
interwoven, that it is not easy to determine which has the prior claim
to description, but we will begin with the egg.
With very few exceptions, such as the Earwig, which watches over its
eggs and young like a hen over her nest and chickens, the insects merely
deposit their eggs upon or close to the food of the future young, and
leave them to their fate. The eggs of the Gnat, however, require
different treatment. The young larvæ, when hatched, immediately pass
into the water in which they have to live, and yet the eggs are so
constituted that they need the warmth of the sun in order to hatch them.
The machinery by which both these objects are attained is singularly
beautiful.
The shape of the egg very much resembles that of a common ninepin, and
the structure is such that it must be kept upright, so that the top
shall be exposed to the air and sun, and the bottom be immersed in the
water. It would be almost impossible that these conditions should be
attained if the eggs were either dropped separately into the water or
fixed to aquatic plants, as is the case with many creatures whose eggs
are hatched solely in or on the water.
As is the case with many insects, each egg when laid is enveloped with a
slight coating of a glutinous character, so that they adhere together.
And, in the case of the Gnat, this material is insoluble in water, and
hardens almost immediately after the egg is deposited. Taking advantage
of these peculiarities, the female Gnat places herself on the edge of a
floating leaf or similar object, so that her long and slender hind-legs
rest on the water. In some mysterious way, the eggs, as they are
successively produced, are passed along the hind-legs, and are arranged
side by side in such a manner that they are formed into the figure of a
boat, being fixed to each other by the glutinous substance which has
already been mentioned.
It is a very remarkable fact, which assists in strengthening the theory
on which this book is written, that the lines of the best modern
life-boats are almost identical with those of the Gnat-boat, and that
both possess the power of righting themselves if capsized. In all trials
of a new life-boat, one of the most important is that which tests her
capability of self-righting; and any one who has witnessed such
experiments, and has tried to upset a Gnat-boat, cannot but be struck
with the singular similitude between the boat made by the hand of man
and that constructed by the legs of an insect, without even the aid of
eyes.
Push the Gnat-boat under water, and it shoots to the surface like a
cork, righting itself as it rises. Pour water on it, and exactly the
same result occurs, so that nothing can prevent it from floating. Then,
when the warm air has done its work in hatching the enclosed young, a
little trap-door opens at the bottom of the egg, lets the young larvæ
into the water, and away they swim.
Now we come to another phase of existence in which the Gnat forms a
boat. Every one knows the little active Gnat larvæ, with their large
heads and slender bodies, much like tadpoles in miniature. When they
have reached their full growth, and assume the pupal form, their shape
is much changed. The fore part of the body is still more enlarged, as it
has to contain the wings and legs, which have so great a proportion to
the body of the perfect Gnat. And, instead of floating with its head
downwards, and breathing through its tail as it did when a larva, it now
floats with the head uppermost, and breathes through two little tubes.
Even in its former state the creature had something almost grotesque in
its aspect, the head, when magnified, looking almost as like a human
face as does that of a skate. But in its pupal state it looks as if it
had put on a large comical mask much too large for it, very much like
those paper masks which are enclosed in crackers, and have to be worn
by those who draw them.
In process of time the pupa changes to a perfect Gnat within this shelly
case, able to move, but unable to eat. The body shrinks in size, and the
wings and legs are formed, both being pressed closely to the body. When
the Gnat is fully developed, the pupal skin splits along the back, and
opens out into a curiously boat-like shape, the front, which contains
the heavier part of the insect, being much the largest, and consequently
being able to bear the greatest weight.
By degrees, the Gnat draws itself out of the split pupal skin, resting
its legs on it as fast as they are released. It then shakes out its
wings to dry, and finally takes to the air.
It is a really wonderful fact that the insect which, for three stages in
life--namely, an egg, larva, and pupa--lived in the water, should in the
fourth not only be incapable of aquatic life, but should employ its old
skin to protect it from that very element in which it was living only a
minute or two before.
Should the reader wish to examine for himself either the egg or skin
boat of the Gnat, he can easily procure them by searching any quiet
pond, or even an uncovered water-butt. They are, of course, very small,
averaging about the tenth of an inch in length, and are nearly always to
be found close to the side either of pond or tub, being drawn there by
the power of attraction.
I may here mention that there are other dipterous insects belonging to
the genus Stratiomys, which undergo their metamorphosis in a very
similar fashion. In these insects, the larva breathes through the tail,
and when it attains its pupal condition, the actual insect is very much
smaller than the pupal skin, only occupying the anterior and enlarged
part. Indeed, the difference of size is so great, that several
entomologists believed the future Stratiomys to be but a parasite on the
original larva. The beautiful Chameleon-fly (_Stratiomys chamæleon_) is
a familiar example of these insects.
NAUTICAL.
CHAPTER II.
THE OAR, THE PADDLE, AND THE SCREW.
Propulsion by the Oar.--Parallels in the Insect World.--The
“Water-boatman.”--Its Boat-like Shape.--The Oar-like Legs.--Exact
mechanical Analogy between the Legs of the Insect and the Oars of
the human Rower.--“Feathering” Oars in Nature and Art.--The
Water-boatman and the Water-beetles.--The Feet of the Swan, Goose,
and other aquatic Birds.--The Cydippe, or Beroë.--The
Self-feathering Paddle-wheel.--Indirect Force.--The Wedge, Screw,
and Inclined Plane.--“Sculling” a Boat.--The “Tanka” Girls of
China.--Mechanical Principle of the Screw, and its Adaptation to
Vessels.--Gradual Development of the Nautical Screw.--Mechanical
Principle of the Tail of the Fish, the Otter, and the sinuous Body
of the Eel and Lampern.--The Coracle and the Whirlwig-beetle.
The Boat naturally reminds us of the Boatman. In the two gnat-boats
which have been described there is no propelling power used or needed,
the little vessel floating about at random, and its only object being to
keep afloat. But there are many cases where the propelling power is
absolutely essential, and where its absence would mean death, as much as
it would to a ship which was becalmed in mid ocean without any means of
progress or escape. There are, for example, hundreds of creatures,
belonging to every order of animals, which are absolutely dependent for
their very existence on their power of propulsion, and I believe that
there is not a single mode of aquatic progression employed by man which
has not been previously carried out in the animal world. There are so
many examples of this fact that I am obliged to select a very few
typical instances in proof of the assertion.
Taking the Oar as the natural type of progression in the water, we have
in the insect world numerous examples of the very same principle on
which our modern boats are propelled. And it is worthy of notice, that
the greater the improvement in rowing, the nearer do we approach the
original insect model.
The first which we shall notice is the insect which, from its singular
resemblance to a boat propelled by a pair of oars, has received the
popular name of WATER-BOATMAN. Its scientific name is _Notonecta
glauca_, the meaning of which we shall presently see. It belongs to the
order of Heteroptera, and is one of a numerous group, all bearing some
resemblance to each other in form, and being almost identical in habits.
Though they can fly well, and walk tolerably, they pass the greater part
of their existence in the water, in which element they find their food.
Predacious to a high degree, and armed with powerful weapons of offence,
it is one of the pirates of the fresh water, and may be found in almost
every pond and stream, plying its deadly vocation.
Its large and powerful wings seem only to be employed in carrying it
from one piece of water to another, while its first and second pairs of
legs are hardly ever used at all for progression. The last pair of legs
are of very great length, and furnished at their tips with a curiously
constructed fringe of stiff hairs. The body is shaped in a manner that
greatly resembles a boat turned upside down, the edge of the elytra
forming a sort of ridge very much like the keel of the boat.
When the creature is engaged in swimming, it turns itself on its back,
so as to bring the keel downwards, and to be able to cut the water with
the sharp edge. From this habit it has derived the name of Notonecta,
which signifies an animal which swims on its back. The first and second
pairs of legs are clasped to the body, and the last pair are stretched
out as shown in the illustration, not only looking like oars, but being
actually used as oars.
Now, I wish especially to call the reader’s attention to the curiously
exact parallel between the water-boatman and the human oarsman. As the
reader may probably know, the oar is a lever of the second order, _i.e._
the power comes first, then the weight, and then the fulcrum. The arm of
the rower furnishes the power, the boat is the weight to be moved, and
the water is the fulcrum against which the lever acts.
I have more than once heard objections to this definition, the objectors
saying that the water was a yielding substance, and therefore could not
be the fulcrum. This objection, however, was easily refuted by taking a
boat up a narrow creek, and rowing with the oar-blades resting on the
shore, and not in the water.
[Illustration: OAR-LEG OF WATER-BOATMAN.]
[Illustration: OAR OF BOAT.]
[Illustration: WATER-BOATMAN ROWING ITSELF.]
[Illustration: OARSMAN ROWING.]
Now, the swimming legs of the water-boatman are exact analogues of the
oars of a human rower. The internal muscles at the juncture of the leg
with the body supply the place of the rower’s arms, the leg itself takes
the office of the oar, and the body of the insect is the weight to be
moved, and the water supplies the fulcrum. Even the broad blade at the
end of the oar is anticipated by the fringe of bristles at the end of
the leg, and its sharpened edge by the shape of the insect’s limb.
Besides these resemblances, there is another which is worthy of notice.
All rowers know that one of their first lessons is to “feather” their
oars, _i.e._ to turn the blade edgewise as soon as it leaves the water.
Nothing looks more awkward than for a boatman to row without feathering.
(We all must remember the eulogy on the “Jolly Young Waterman,” who
“feathered his oars with skill and dexterity.”) In the first place, he
must lift his oar very high out of the water, and, in the second, he
will be impeded by any wind that happens to come against the blades.
The Water-boatman, however, does not lift its legs out of the water
after every stroke, as a human boatman does, and therefore it has no
need to feather in the same way. But there is even greater need for a
feathering of some kind in the insect’s leg, on account of the greater
resistance offered by water than by air, and this feathering is effected
by the arrangement of the blade-bristles, which spread themselves
against the water as the stroke is made, and collapse afterwards, so as
to give as little resistance as possible when the stroke is completed.
* * * * *
IN Art we have invented many similar contrivances, but I believe that
there is not one in which we have not been anticipated by Nature.
Putting aside the insect which has just been described, we have the
whole tribe of water-beetles, in which the same principle is carried out
in an almost identical manner. In the accompanying illustration, the
oar, the rower, and the boat are placed above one another, and next to
them are seen one of the oar-legs of the water-boatman and the insect as
it appears when swimming on its back.
Then, there is the foot of the duck, goose, swan, and various other
aquatic birds, in which the foot presents a broad blade as it strikes
against the water, and a narrow edge as it recovers from the stroke.
Some years ago, a steam yacht was built and propelled by feet made on
the model of those of the swan. She was a very pretty vessel, but art
could not equal nature, and at present the swan-foot propeller, however
perfect in theory, has not succeeded in action. Perhaps, if some
nautical engineer were to take it in hand, he would procure the desired
result.
Almost exactly similar is the mode of propulsion employed by the
lobster, the prawns and shrimps, their tails expanding widely into a
fan-like shape as they strike against the water, and then collapsing
when the stroke is withdrawn, so as to allow them to pass through the
water with the least possible resistance.
The same principle is to be seen in the lively little Acaleph, for which
there is unfortunately no popular name, and which we must therefore call
by its scientific title of CYDIPPE, or Beroë, these names being almost
indifferently used. When full grown, it is about as large as an acorn,
and very much of the same shape. It is as transparent as if made of
glass, and, when in the water, is only visible to practised eyes.
_En passant_, I may remark that the familiar term of “water,” when
applied to diamonds, is owing to their appearance when placed in
distilled water. Those which can be at once seen are called stones of
the second water. Those which cannot be seen, because their refractive
powers are equal to those of the water, are called “diamonds of the
first water,” and are very much more valuable than the others.
As the Cydippe is, in fact, little more than sea-water, entangled in
the slightest imaginable and most transparent tissue of animal fibre, it
is evident that the water and the Cydippe must be of almost equal
refracting power, and that therefore the acaleph must be as invisible as
diamonds of the “first water.” Indeed, I have often had specimens in a
glass jar which were absolutely invisible to persons to whom I wished to
show them.
But an experienced eye detects the creature at once. Along its body, at
equal distances, are eight narrow bands, over which the colours of the
rainbow are, though very faint, perpetually rippling. This appearance is
caused by the machinery which impels the body, and which seems never to
cease. Each of these bands is composed of a vast number of tiny flaps,
which move up and down in regular succession, so as to cause the light
to play on their surfaces. And, as they move as if set on hinges, they
of course offer no resistance to the water after their stroke is made.
[Illustration: CYDIPPE AND PADDLES.]
[Illustration: PRAWN SWIMMING.
FEET of DUCK.]
[Illustration: SELF-FEATHERING PADDLE-WHEEL.]
Now let us compare these works of nature with those of art. We have
already seen the parallels of the oar, and we now come to those of the
paddle-wheel. When paddle-steamers were first invented, the blades were
fixed and projected from the wheel, as if they had been continuations of
its spokes. It was found, however, that a great waste of power, together
with much inconvenience, was caused by this arrangement. Not only was a
considerable weight of water raised by each blade after it passed the
middle of its stroke, but the steam power was given nearly as much to
lifting and shaking the vessel as to propulsion.
A new kind of paddle-wheel was then invented, in which the blades were
ingeniously jointed to the wheel, so that they presented their flat
surfaces to the water while propelling, and their edges when the stroke
was over. This, which is known by the name of the “Self-feathering
Paddle-wheel,” was thought to be a very clever invention, and so it was;
but not even the inventors were likely to have known that if they had
only looked into the book of Nature, they might have found plenty of
self-feathering paddle-wheels, beside the few which my limited space
enables me to give.
If the reader will look at the illustration, he will see that on one
side is represented the self-feathering paddle-wheel of Art, with its
ingenious arrangement of rods and hinges. On the other side there comes,
first, the common Prawn, shown with its tail expanded in the middle of
its stroke.
Just below it is a Cydippe of its ordinary size, showing the
paddle-bands, one of which is drawn at the side much magnified, so as to
show the arrangement of the little paddles. As to the tentacles which
trail from the body, we shall treat of them when we come to our next
division of the subject of the work.
Lastly, there is a representation of the self-feathering feet of the
Duck, the left foot expanded in striking the water, and the right closed
so as to offer no resistance when drawn forward for another stroke. The
swan’s foot shows this action even more beautifully than does that of
the duck.
* * * * *
WE now come to another mode of propulsion, namely, that which is not due
to direct pressure of a more or less flat body against the water, but to
the indirect principle of the screw, wedge, or inclined plane.
Space being valuable, I will only take two instances, namely, the
well-known mode of propelling a boat by a single oar working in a groove
or rowlock in the middle of the stern, and the ordinary screw of modern
steamers.
Most of my readers must have seen a sailor in the act of “sculling” a
boat. A tolerably deep notch is sunk in the centre of the stern, and the
oar is laid in it, as shown in the central illustration, on the
right-hand side. The sailor then takes the handle of the oar, and works
it regularly backwards and forwards, without taking the blade out of the
water. The boat at once begins to move forward, and, when the oar is
urged by a strong and experienced man, can be propelled with wonderful
speed. The well-known “Tanka” boat-girls of China never think of using
two oars, a single oar in the stern being all-sufficient for the rapid
and intricate evolutions required in their business.
[Illustration: TAIL OF FISH.]
[Illustration: SCREW OF STEAMER.]
[Illustration: TAIL OF OTTER.]
[Illustration: “SCULLING” A BOAT.]
[Illustration: TAIL OF SEAL.]
[Illustration: ACTION OF RUDDER.]
The mechanical process which is here employed is nothing more than that
of the inclined plane, or rather, the wedge, the oar-blade forming the
wedge, and the force being directed against the stern of the boat, and
so driving it through the water.
The Rudder affords another example of a similar force, although it is
used more for directing than propelling a vessel. Still, just as the
scull is used not only for propelling, but for steering the boat, the
rudder, when moved steadily backwards and forwards, can be used for
propulsion as well as steerage. In the absence of oars, this property is
most useful, as I can practically testify.
So different in appearance are the screw and the inclined plane, that
very few people would realise the fact that the screw is nothing but an
inclined plane wound round a cylinder, or rather, is a circular inclined
plane. The ordinary corkscrew is a good example of this principle, the
cylinder being but an imaginary one.
Now, if the screw be turned round, it is evident that force is applied
just on the principle of the wedge, and this principle is well shown in
the various screw-presses, of which the common linen-press is a familiar
example, as was the original printing-press, which still survives as a
toy for children.
We all know the enormous force exerted by screws when working in wood,
and how, when the screw-driver is turned in the reverse direction, the
instrument is forced backwards, though the operator is leaning against
it with all his weight. In fact, a comparatively small screw, if working
in hard wood or metal, so that the threads could not break, could lift a
heavy man.
Substitute water for wood or metal, and the result would be the same in
principle, though the resistance would be less. As the loss of power by
friction would prevent a large vessel from being propelled by a stern
oar moved like a scull, the idea was invented of applying the same kind
of power by a large screw, which should project into the water from the
stern of the vessel. This modification, moreover, would have the
advantage of forcing the vessel forward when the screw was turned from
left to right, and drawing it back when turned in the opposite
direction, whereas the sculling oar would only drive it forward.
The principle was right enough, but there was at first a great
difficulty in carrying it out. Firstly, several turns of a large screw
were used, and were found to need power inadequate to the effect. Then
the screw was reduced to four separate blades, and now only two are
used, as shown in the illustration, these saving friction, being equally
powerful for propulsion, and running less risk of fouling by rigging
blown overboard or other floating substances.
So much for Art. Now for the same principle as shown in Nature, of which
I can take but a very few instances.
The first and most obvious example is that of the Fish-tail, which any
one may observe by watching ordinary gold fish in a bowl. Their
progression is entirely accomplished by the movement of the tail from
side to side, exactly like that of the sculling oar, and moreover, like
the oar, the tail acts as rudder as well as propeller.
The force with which this instrument can be used may be estimated by any
one who is an angler, and knows the lightning-like rush of a hooked
trout, or who has seen the wonderful spring with which a salmon shoots
clear out of the water, and leaps up a fall several feet in height. This
is not done, as many writers state, by bending the body into a bow-like
form, and then suddenly straightening it, but by the projectile force
which is gained by moving the tail backwards and forwards as a sculler
moves his oar.
Perhaps some of my readers have seen the wonderful speed, ease, and
grace with which an Otter propels itself through the water. As the otter
feeds on fish, and can capture even the salmon itself, its powers of
locomotion must be very great indeed. And these are obtained entirely by
means of the tail, which is long, thick, and muscular, and can be swept
from side to side with enormous force, considering the size of the
animal. The legs have little or nothing to do with the act of swimming.
The fore-legs are pressed closely against the body, and the hind-legs
against each other. The latter act occasionally as assistants in
steering, but that is all.
Then there are the various Seals, whose hind-legs, flattened and pressed
together, act exactly like the tail of the fish, that of the otter, the
oar of the sculler, or the screw of the steamer. Also, the eel, when
swimming, uses exactly the same means, its lithe body forming a
succession of inclined planes; so does the snake, and so does the pretty
little lampern, which is so common in several of our rivers, and so
totally absent from others.
I can only now give a short description of the woodcut which illustrates
these points.
On the right hand Art is shown by the screw-blades of the modern
steamer. In the middle is the ordinary mode of sculling a boat by an oar
in the stern, and below it is the rudder, which, like the sculling oar,
may be used either for propulsion or direction.
On the left hand we have three examples of the same mechanical powers
as shown in Nature. The uppermost figure represents a fish as in the act
of swimming, the dotted lines showing the movement of its tail, and the
principle of the wedge. In the middle is an otter, just preparing to
enter the water, and below is a seal, both of them showing the identity
of mechanism between themselves and the art of man. I need not say that
the mechanism of art is only a feeble copy of that of nature, but
nothing more could be expected.
* * * * *
WHILE we are on this subject I may as well mention two more applications
of the screw principle. The first is the windmill, the sails of which
are constructed on exactly the same principle as the blades of the
nautical screw. Only, as they are pressed by the wind, and the mill
cannot move, they are forced to revolve by the pressure of the wind,
just as the screw of a steamer revolves when the vessel is being towed,
and the screw left at liberty.
Moreover, just as the modern screws have only two blades, so, many
modern windmills have only two sails, the expense and friction being
lessened, and the power not injured.
Again: some years ago there was a very fashionable toy called the aërial
top. It was practically nothing but a windmill in miniature, rapidly
turned by a string, after the manner of a humming-top. The edges of the
sails being turned downwards, the instrument naturally screwed itself
into the air to a height equivalent to the velocity of the motion.
A similar idea has been mooted with regard to the guidance of balloons,
or even to aërial voyaging without the assistance of gas, but at present
the weight of the needful machinery has proved to be in excess of the
required lifting power.
In fine, the application of the inclined plane, wedge, or screw as a
motive power, is so wide a subject that I must, with much reluctance,
close it with these few and obvious examples.
* * * * *
IT is worth while, by the way, to remark how curiously similar are such
parallels. I have already mentioned the very evident resemblance between
the water-boatman, the water-beetles, and the human rower, the body of
the insect being shaped very much like the form of the modern boat. I
must now draw the attention of the reader to the similitude between the
very primitive boat known by the name of Coracle, and the common
Whirlwig-beetle (_Gyrinus natator_), which may be found in nearly every
puddle. The shape of the insect is almost identical with that of the
boat, and the paddle of the coracle is an almost exact imitation of the
swimming legs of the whirlwig. And, as if to make the resemblance
closer, many coraclers, instead of using a single paddle with two broad
ends, employ two short paddles, shaped very much like battledores.
[Illustration: WHIRLWIG BEETLE AND PADDLES.]
[Illustration: CORACLE AND PADDLE.]
NAUTICAL.
CHAPTER III.
SUBSIDIARY APPLIANCES.--PART I.
General Sketch of the Subject.--The Mast of Wood and Iron.--Analogy
between the Iron Mast and the Porcupine Quill.--The Iron Yard and
its Shape prefigured by the same Quill.--Beams of the
Steam-engine.--Principle of the Hollow Tube in place of the Solid
Bar.--Quills and Bones of Birds.--Wheat Straws and
Bamboos.--Structure of the Boat.--The Coracle, the Esquimaux Boat,
and the Bark Canoe.--Framework of the Ship and Skeleton of the
Fish.--Compartments of Iron Ship and Skull of Elephant.--The Rush,
the Cane, and the Sugar-cane.--“Stellate” Tissue and its Varieties.
Having now treated of the raft, the boat, the ship, and their various
modes of propulsion and guidance, we come to the subsidiary appliances
to navigation, if they may be so called in lack of a better name.
First in importance is necessarily the mast; and the yards, which
support the sails, are naturally the next in order. Then there come the
various improvements in the building of vessels; namely, the
substitution of planks fastened on a skeleton of beams for a mere
hollowed log, and the subsequent invention of iron vessels with their
numerous compartments, giving enormous strength and size, with very
great comparative lightness.
Then we come to the various developments of the ropes or cables, by
which a vessel is kept in its place when within reach of ground, whether
on shore or at the water-bed. Next come the different forms of anchors
which fasten a vessel to the bed of the ocean, of grapnels by which she
can be made fast to the shore, or of “drags,” which at a pinch can
perform either office, and can besides be utilised in searching for and
hauling up objects that are lying at the bottom of the sea.
Next we come to the boat-hook, which is so useful either as a temporary
anchor, or as a pole by which a boat can be propelled by pushing it
against the shore or the bed of the water; and then to the “punt-pole,”
which is only used for the latter purpose.
Lastly, we come to the life-belt and life-raft, which are now occupying,
and rightly, so much of the public attention. These subjects will be
treated in their order in the present chapter, and I hope to be able to
show the reader that in all these points nature has anticipated art.
I presume that most, if not all, of my readers are aware of the rapidly
extending use of iron in ship-building, not only in the standing
rigging, but in the material of the vessel. First there came iron
“knees,” _i.e._ the angular pieces of wood which strengthen the
junctions of the timbers. Formerly these were made of oak-branches, and,
as it was not easy to find a bough which was naturally bent at such an
angle as was required for a “knee,” such branches were exceedingly
valuable. Iron, however, was then employed, and with the best results.
It was lighter than the wooden knee, was stronger, could be bent at any
angle, and took up much less space.
By degrees iron was used more and more, until vessels were wholly made
of that material. Then the masts, and even the yards, were made of iron,
and, strange as it may appear, were found to be lighter as well as
stronger than those made of wood. Of course, the masts and yards were
hollow, and it was found by the engineers that in order to combine
lightness with great strength, the best plan was to run longitudinal
ridges along the inside of the tube.
A section of one of these masts is given at Fig. B, and taken from the
drawings of one of our largest engineering firms. The reader will see
that the mast is composed of rather slight material, and that it is
strengthened by four deep though thin ribs, which run throughout its
length.
When I first saw this mast I was at once struck with the remarkable
resemblance between it and the quill of the Porcupine. These quills, as
all anglers know, are very light, and of extraordinary strength when
compared with their weight. Indeed, they are so light that they are
invaluable as penholders to those who are obliged to make much use of
their pen. I have used nothing else for a very long time, and the
drawing of the Porcupine quill which is here given at Fig. A was made
from a small piece cut from the top of the penholder which I have used
for some fifteen years, and with which all my largest and most important
works were written, including the large “Natural History,” “Homes
without Hands,” “Man and Beast,” &c., &c. A portion of the same quill is
also shown of its real size.
If the reader will cut a Porcupine quill at right angles, make a thin
section of it, and place it under the microscope, or even under an
ordinary pocket lens, he will see that the exterior is composed of a
very thin layer of horny matter, and the interior filled with a vast
number of tiny cells, which are formed much on the same plan as the pith
of elder and other plants. The analogies of the pith will be treated in
another page.
[Illustration:
PORTION OF PORCUPINE QUILL. SECTION OF ENGINE BEAM.
COMPLETE QUILL. IRON YARD AND YARD-ARM.
BAMBOO. ENGINE BEAM.
SECTION OF PORCUPINE QUILL MAGNIFIED. SECTION OF IRON MAST.]
But were the quill merely a hollow tube filled with pith, it would be
too weak to resist the strain to which it is often liable. Consequently
it is strengthened by a number of internal ribs, composed of the same
horny material as the outer coat, and arranged in exactly the same way
as those of the mast.
There are yet other points in the structure of the Porcupine quill which
might be imitated with advantage in the mast. In the first place, the
internal ribs are much more numerous than those of the mast, but they
are very much thinner, and taper away from the base, where the greatest
strain exists, to the end, where they come to the finest imaginable
edge. This modification of structure enables the outer shell of the
quill to be exceedingly thin and light, and, moreover, gives to the
whole quill an elasticity which is quite wonderful, considering its
weight and strength.
Then, in the iron mast the exterior is quite smooth, whereas in the
Porcupine quill it is regularly indented, exactly on the principle of
the corrugated iron, which combines great strength with great lightness.
And I cannot but think that our iron masts might be made both lighter
and stronger if the shell were thinner, the internal ribs made like
those of the Porcupine quill, and the shell corrugated instead of being
quite smooth. The internal cells of the quill are, of course, not needed
in the mast, as they are intended for nutrition, and not for strength.
* * * * *
BEING on this subject, we may take the shape of the Porcupine quill, and
compare it with that of the ship’s yard. It will be seen that the two
are so exactly similar in form that the outline of one would answer
perfectly well for the other. The only perceptible difference is, that
in the ship’s yard both ends are alike, whereas in the Porcupine quill
the end which is inserted in the skin is rounded and slightly bent,
while the other end is sharply pointed.
The principal point to be noticed in the form of both quill and yard is,
that they become thicker in the centre, that being the spot on which the
greatest strain comes, and which, in consequence, needs to be stronger
than any other part. While holding and balancing the pole which Blondin
uses to preserve his balance when walking on the high rope, I was struck
with the fact that the pole, which is heavily weighted at each end, had
to be strengthened in the middle, exactly on the principle of the
Porcupine quill and the ship’s yard. It could not, of course, be
thickened, as the hands could not grasp it, but it had to be furnished
with additional strengthening. And the necessity of such strengthening
is evident from the fact that on one occasion the pole did break in the
middle, so that any one of less nerve and presence of mind must have
been killed.
Bearing in mind, then, that in a rod or pole the centre is the part
which most requires to be strengthened, we can see, in cases too
numerous to mention, how art has followed, though perhaps unconsciously,
in the footsteps of nature. Take, for example, the beam of a
steam-engine, such as is given in the sketch, and for which the great
engine at Chatham acted as model. The reader will observe that in this
case the beam is gradually thickened towards the centre, the ends, where
the strain is slightest, being comparatively small.
Another point also must be noticed. Equal strength could have been
obtained had the beam been solid, but at the expense of weight, and
consequent waste of power. Lightness is therefore combined with strength
by making the beam consist of a comparatively slight centre, but having
four bold ridges, as shown in the section given in the accompanying
illustration. This plan, as the reader will see, is exactly the same as
that which is adopted in the iron mast and porcupine quill, except that
the ridges are external instead of internal. The same mode of
construction is employed in ordinary cranes, the principal beam of which
is almost identical in form with that of the engine, both being thickest
in the centre, and both strengthened with external ridges.
There are also other analogies between the hollow mast and natural
objects. Keeping still to the animal world, we find the quill feathers
of the flying birds to supply examples of the combination of great
strength with great lightness and very little expenditure of material.
Their wing bones, too, are hollow, communicating with the lungs, and are
consequently light as well as strong.
Passing to the vegetable world, we find a familiar example of this
structure in the common Wheat Straw. The ripe ear is so heavy, when
compared with the amount of material which can be spared to carry it,
that if the stalk were solid it would give way under the mere weight of
the ear. Moreover, the full-grown corn has to endure much additional
weight when wetted with rain, and to resist much additional force when
bowed by the wind, so that a slight and solid stalk would be quite
inadequate to the task of supporting the ear.
The material of the stalk is therefore utilised in a different manner,
being formed into a hollow cylinder, the exterior of which is coated
with a very thin shell of flint, or “silex” as it is scientifically
termed. The result of this structure is that the stem possesses
strength, lightness, and elasticity, so as to be equal to the burden
which is laid upon it.
Then there is the common Bamboo, which is little more than a magnified
straw, being constructed in much the same manner, and possessing almost
the same constituents of vegetable matter and silex.
Perhaps the most extraordinary of the tubal system is to be found in the
remarkable plant of Guiana called by the natives Ourah, and
scientifically known by the name of _Arundinaria Schomburgkii_. Like the
bamboo, it grows in clusters, and has a feathery top, which waves about
in the breeze. But, instead of decreasing gradually in size from the
base upwards, the Ourah, although it runs to some fifty feet in height,
is nowhere more than half an inch in diameter. The first joint is about
sixteen feet in length, and uniform in diameter throughout.
It is scarcely thicker than ordinary pasteboard, and yet so strong and
elastic is it, that it can sustain with ease the weight and strain of
its feathery top as it blows about in the breeze. The natives of certain
parts of Guiana use this reed as a blow-gun, and I have a specimen,
presented to me by the late Mr. Waterton, which is eleven feet in
length.
So the reader will see that when engineers found that hollow iron beams
were not only lighter, but stronger than solid beams, they were simply
copying the hollow beams formed by Nature thousands of years ago.
* * * * *
ANOTHER great improvement in ship-building now comes before us.
We have already seen that the earliest boats were merely hollowed logs,
just as Robinson Crusoe is represented to have made. But these had many
disadvantages. They were always too heavy. They were liable to split, on
account of flaws in the wood, and if a large vessel were needed, it was
difficult to find a tree sufficiently large, or to get it down to the
water when finished.
So the next idea was to build a skeleton, so to speak, of light wooden
beams, and to surround it with an outer clothing, or skin, if it may be
so termed. As far as I know, the two original types of this structure
are the Coracle of the ancient Briton, and the birch-bark Canoe of the
North American Indian, and it is not a little remarkable that both exist
to the present day, with scarcely any modification.
The Coracle has been already represented on page 22. It is, perhaps, or
was in its original form, the simplest boat in existence, next to the
“dug-out.” In the times of the very ancient Britons, who were content
with blue paint by way of dress, and lived by hunting and fishing, the
Coracle was a basin-shaped basket of wicker-work, rather longer than
wide, and covered with the skin of a wild ox. This was sufficiently
light to be carried by one man, and sufficiently buoyant to bear him
down rapids, if he were a skilful paddler, and, of course, formed a
considerable step in civilisation.
The modern Coracle is identical in form, and almost in material. The
frame is still oval and basin-shaped, and made of wicker, but the outer
covering is not the same. An ox-hide is an expensive article in these
days, and, especially when wetted, is very heavy. So the modern Coracle
builder covers the wicker skin with a piece of tarpaulin, which is much
cheaper than the ox-hide, much lighter, is equally water-tight, and has
the great advantage of not absorbing moisture, so that it is as light
after use as before.
The Esquimaux make a boat on very similar principles. It is simply
hideous in form, resembling a huge washing tub in shape, but, as it is
only intended for the inferior beings called women, this does not
signify.
Best, most perfect, and most graceful of all such boats is the
Birch-bark Canoe of the North American Indians, whose shape has
evidently been borrowed from that of a fish. I have seen many of these
canoes, and have now before me several models which are exactly like the
originals, except in point of size. Instead of being mere elongated
bowls, like the coracle, they are long and slender, swelling out
considerably in the middle, and coming to an almost knife-like edge at
each end. Both stem and stern are alike, so that the canoe can be
paddled in either direction, and, as one of the paddlers always acts as
steersman, no rudder is needed.
The mode of construction is perfectly simple. The labour is divided
between the sexes: the women cut large sheets of bark from the
birch-trees, scrape and smooth them, and then sew them together, so as
to form the outer skin, or “cloak” as it is called, of the canoe.
Meanwhile the men are making the skeleton of strips of white cedar-wood,
and binding them into shape with thongs made of the inner bark of the
same tree, just like the “bass” of our gardeners. The “cloak” is then
gradually worked over the skeleton, sewn into its place, and the canoe
is finished. A figure of this canoe, as completed, is given in the same
illustration as that which represents various forms of boat, page 7.
The last improvement is that which was caused by the necessity for large
vessels, when planks or iron plates were fastened over the skeleton.
But, in all these cases, the vessel is built on the principle of the
thorax of a vertebrate animal, that of the whale or a fish being an
admirable example. It only needs to take the skeleton of a whale, turn
it on its back, and the ribs will be seen to form an almost exact
reproduction of those of any ship being built in the nearest dockyard.
[Illustration: RIBS OF FISH. RIBS OF SHIP.]
I have now before me the spine and ribs of a herring. The fish was
over-boiled, and the flesh fell off the bones as it was being lifted out
of the dish, leaving most of the ribs in their places. When held with
the spine downwards, and viewed from one end, the resemblance to the
framework of a ship is absolutely startling, the ribs representing the
beams, and the spine taking the place of the keel. I have also before me
a sketch representing a section of a Fijian canoe, and it is remarkable
that even the very curve of the ribs of the herring is reproduced in
those of the canoe.
Whether the Fijians derived this peculiar and beautiful curve from the
ribs of a fish I cannot say, but think it very likely.
* * * * *
A STILL greater improvement in ship-building now comes before us, and
this also has been anticipated both in the animal and vegetable
kingdoms. There are so many examples of this anticipation that I can
only give one or two.
The improvement to which I refer is that which is now almost universally
employed in the construction of iron ships, namely, the making the outer
shell double instead of single, and dividing it into a number of
separate compartments. Putting aside the advantage that if the vessel
were stove, only one compartment would fill, we have the fact that the
ship is at the same time enormously strengthened and very light in
proportion to her bulk.
[Illustration:
SECTION OF ELEPHANT SKULL. TRANSVERSE SECTION OF IRON SHIP.
STELLATE TISSUES. LONGITUDINAL SECTION OF IRON SHIP.]
Perhaps the best, and certainly the most obvious, example of this
principle in the animal world is to be found in the skull of the
Elephant. The enormous tusks, with their powerful leverage, the massive
teeth, and the large and weighty proboscis, require a corresponding
supply of muscles, and consequently a large surface of bone for the
attachments of these muscles. Now, were the skull solid in proportion to
its requisite size, its weight would be too much for the neck to endure,
however short and sturdy it might be. The mode of attaining expanse of
surface, together with lightness of structure, is singularly beautiful.
Perhaps some of my readers may not be aware that the bone of the skull
consists of an outer and inner plate, with a variable arrangement of
cells between them. In many animals, such, for example, as man, where
the jaws are comparatively feeble, and the teeth small and light, the
size of the skull is practically that of the brain, to which it affords
a covering. The same structure may be observed in the skull of the
common sparrow, where, as in man, the two bony plates are set almost in
contact.
But in the elephant these external and internal plates are set widely
apart, and the space between them is filled with bony cells, much
resembling those of a honeycomb. They are, in fact, just the same cells
as those which exist in the skull of man and sparrow, but they are very
much enlarged, and in consequence give a large surface, accompanied with
united strength and lightness.
There are many other examples in the animal kingdom, but our limited
space will not allow them to be even mentioned.
* * * * *
AS to the vegetable examples of this principle, they are so
multitudinous that only a very slight description can be given of them.
I suppose that most boys have seen a “cane” (whether they have felt it
or not is not to the purpose), and some boys have made sham cigars from
pieces of cane. In either case they must have noticed that the cane is
not solid, but is pierced with a vast number of holes, passing
longitudinally through it, and is, in fact, a collection of little tubes
connected and bound together by a common envelope.
The Sugar-cane, if cut across, is seen also to consist of multitudinous
cells, which, however, are not hollow, but filled with the sweet liquid
from which sugar is obtained by boiling. Then there are many of our
common English plants, like the ordinary rush or reed, which are very
slight in diameter in comparison with their length, and in which the
cells are still further strengthened and lightened by the projection of
their sides into a number of points which meet each other, and leave
interstices between them. This modification of the cellular system is
called “Stellate” (or star-like) Tissue, and two examples of it are
given in the illustration, one being taken from the common rush, and the
other from the seed-coat of the privet. A very good specimen of stellate
tissue may be obtained by cutting a thin section of the white inner peel
of the orange.
NAUTICAL.
CHAPTER IV.
SUBSIDIARY APPLIANCES.--PART II.
The Cable and its Variations.--Material of Cables.--Hempen and Iron
Cables, and Elasticity of the latter.--Natural Cables.--The
“Byssus” of the Pinna and the common Mussel.--The Water-snail and
its Cable.--A similar Cable produced by the common White Slug.--The
Principle of Elasticity.--Elastic Cable of the Garden
Spider.--Tendrilous Cables of the Pea and the Bryony.--The
Vallisneria, and its Development through the Elastic
Cable.--Proposed Submarine Telegraph Cable.--The Anchor, Grapnel,
and their Varieties.--Natural Anchors.--Spicule of Synapta.--The
Grapnel, natural and artificial.--Ice-anchor and Walrus Tusks.--The
Mushroom Kedge.--The Flesh-hook.--Eagle-claw.--The Grapple-plant of
South Africa.--The Drag.
Among the most important accessories to a ship are the Cable, by which
she can be anchored to the bed of the sea, and the ropes called “warps,”
by which she can be fastened to the land.
Perhaps my readers may not know the old riddle--“How many ropes are
there on board a man-of-war?” The non-nautical individual cannot answer,
but the initiated replies that there are only three, namely, the
man-rope, the tiller-rope, and the rope’s-end, all the others being
“tacks,” “sheets,” “haulyards,” “stays,” “braces,” &c.
Formerly cables were always made of hemp, enormously thick, and most
carefully twisted by hand. Now, even in small vessels, the hempen cable
has been superseded by the iron chain, and this for several reasons.
In the first place, it is much smaller in bulk, and therefore does not
occupy so much room. In the next place, it is even lighter than the
hempen cable of corresponding strength; and, in the third, its specific
gravity--_i.e._ its weight when compared with an equal bulk of
water--is so great, that when submerged, it falls into a sort of
arch-like form, and so attains an elasticity which takes off much of the
strain on the anchor, and protects it from dragging.
* * * * *
WE will now look to Nature for Cables.
[Illustration:
EGG OF DOG-FISH. PINNA. ANCHORED BOAT.
WATER-SNAIL ANCHORED
TO WATER-LILY LEAF.]
The natural cable which will first suggest itself is evidently that of
the Pinna Shell (_Pinna pectinata_), which fixes its shell to some rock
or stone with a number of silk-like threads, spun by itself, and
protruding from the base, just as a vessel on a lee shore throws out a
number of cables. The threads which compose the “byssus,” as it is
called, are only a few inches in length, and apparently slight. They
are, however, really strong, and by acting in unison enable the shell,
though sometimes two feet in length, to be held firmly to the rock. I
may here mention that they have been occasionally woven into gloves, and
other articles of apparel, to which their natural soft grey-brown hue
gives a very pleasing appearance.
A still more familiar instance of a natural marine cable is given by the
common Mussel, which can be found in thousands on almost every solid
substance which affords it a hold. Even copper-bottomed ships are often
covered with Mussels, all clinging by their natural cables, and it is
thought that the cases which sometimes occur of being poisoned by eating
Mussels, or “musselled,” as the malady is called by the seafaring
population, are due to the fact that the Mussels have anchored
themselves to copper, and have in consequence imbibed the verdigris.
* * * * *
PASSING from salt to fresh water, we come to a natural cable which is
very common, and yet, on account of its practical invisibility, is
almost unknown, except by naturalists. I refer to the curious cable
which is constructed by the common Water-snail (_Limnæa stagnalis_),
which has already been mentioned in its capacity of a boat.
This creature has a way of attaching itself to some fixed object, such
as a water-lily leaf, by means of a gelatinous thread, which it can
elongate at pleasure, and by means of which it can retain its position
in a stream, or in still water can sink itself to the bottom, and ascend
to the same spot. This cable seems to be made of the same glairy
secretion as that which surrounds the egg-masses which are found so
plentifully on leaves and stones in our fresh waters, and, like that
substance, is all but invisible in the water, so that an inexperienced
eye would not be able to see it, even if it were pointed out.
Slight, gelatinous, and almost invisible in the water as is this thread,
its strength is very much greater than might be supposed. Not only can a
mollusc be safely moored in the water by such a cable, but it can be
actually suspended in the air, as may be seen from a letter in
Hardwicke’s _Science Gossip_ for 1875, p. 190:--
“Last summer (September 29) I met with the following unusual fact. In a
green-house, from a vine-leaf which was within a few inches of the glass
... a slug was hanging by a thread, which was more than four feet in
length, not unlike a spider-web, but evidently much stronger.
“The slug was descending by means of this thread, and, as the glutinous
matter from the under part of the body was drawn out by the weight of
the creature, it was consolidated into a compact thread by the slug
twisting itself in the direction of the hands of a clock, the power of
twisting being given by the head, and the part of the body nearest the
head being turned in the direction of the twist. There was no tendency
to turn in the contrary direction. Evidently the thread became hard as
soon as it was drawn away from the body.
“By wetting the sides of slips of glass, I secured two specimens of the
thread. In one of these, part was stretched, and part quite loose, the
latter appearing flat when seen through a microscope. The thread, which
was highly elastic, was increased about three inches in a minute. The
slug was white, and about an inch and a half in length.”
* * * * *
NOW we come to the elastic system of the Chain Cable, and find it
anticipated in Nature in various ways.
One curious example was that of a Spider, which found its wheel-like net
in danger from a tempestuous wind. The Spider descended to the ground, a
depth of about seven feet, and, instead of attaching its thread to a
stone or plant, fastened it to a piece of loose stick, hauled it up a
few feet clear of the ground, and then went back to its web. The piece
of stick thus left suspended acted in a most admirable manner, giving
strength and support, and at the same time yielding partly to the wind.
By accident the thread became broken, and the stick, which was about as
thick as an ordinary pencil, and not quite three inches in length, fell
to the ground. The Spider immediately descended, attached another
thread, and hauled it up as before. In a day or two, when the
tempestuous weather had ceased, the Spider voluntarily cut the thread,
and allowed the then useless stick to drop.
* * * * *
A CURIOUS example of the elastic cable is seen in the egg-case of the
Dog-fish, which is given on page 35. The egg-case is formed like that of
the common skate, and has a projection from each of its angles. But the
projections, instead of being mere flattened horns, are lengthened into
long elastic strings, tapering towards the ends, and twisted spirally,
like the tendrils of a grape-vine.
These tendril-like appendages twist themselves round seaweeds and other
objects, and, on account of their spiral form, can hardly ever be torn
from their attachments. Sometimes after a storm the egg is thrown on the
shore, still clinging to the seaweed, but to find an egg detached is
very rarely done.
I have already mentioned the tendrils of the vine, and their great
strength. The reader may remember the corresponding cases of the Pea and
the Bryony, the latter being a most remarkable example of the strength
gained by the spiral form. It clambers about hedges, is exposed to the
fiercest winds, has large and broad leaves, and yet such a thing as a
Bryony being blown off a hedge is scarcely, if ever, seen. I never saw
an example myself, though I have had long experience in hedges.
* * * * *
ANOTHER excellent example of this principle is found in the Vallisneria
plant, which of late years has become tolerably familiar to us through
the means of fresh-water aquaria, though it is not indigenous to this
country.
In this plant the elastic power of the spiral cable is beautifully
developed. It is an aquatic plant, mostly found in running waters, and
has a most singular mode of development. It is diœcious--_i.e._ the
male, or stamen-bearing, and the female, or pistil-bearing flowers, grow
upon separate plants.
It has to deposit its seeds in the bed of the stream, and yet it is
necessary that both sets of flowers should be exposed to the air and sun
before they become able to perform their several duties. Add to this the
fact that the male flower is quite as small in proportion to the female
as is the case with the lac and scale insects, and the problem of their
reaching each other becomes apparently intricate, though it is solved in
a beautifully simple manner.
Fertilisation cannot be conducted by means of insects, as is the case
with so many diœcious terrestrial plants, and it is absolutely
necessary that actual contact should take place between them. This
difficult process is effected as follows:--
The female flowers are attached to a very long spiral and closely coiled
footstalk, and, when they are sufficiently developed, the footstalk
elongates itself until the flower rests on the surface of the water,
where it is safely anchored by its spiral cable, the coils yielding to
the wavelets, and keeping the flower in its place.
Meanwhile the tiny male flowers are being developed at the bottom of the
river, and are attached to very short footstalks. When they are quite
ripe they disengage themselves from their footstalks, and rise to the
surface of the river. Being carried along by the stream, they are sure
to come in contact with the anchored female flowers. This having been
done, and the seeds beginning to be developed, the spiral footstalk
again coils itself tightly, and brings the seeds close to the bed of the
stream, where they can take root.
There are other numerous examples, of which any reader, even slightly
skilled in botany, need not be reminded, most of them being, in one form
or another, modifications of the leaf or the petal, which, after all,
are much the same thing. The vine and passion-flower are, however,
partial exceptions.
I may here mention that soon after the failure of the first Atlantic
telegraph cable, an invention was patented of a very much lighter cable,
enclosed in a tube of india-rubber, and being coiled spirally at certain
distances, so that the coils might give the elasticity which constitutes
strength. The cable was never made, its manufacture proving to be too
costly; but the idea of lightness and elasticity, having been evidently
taken from the spiral tendrils of the bryony, was certainly a good one,
and I should have wished to see it tried on a smaller scale than the
Atlantic requires.
* * * * *
AS a natural consequence, after the cable comes the Anchor, which in
almost every form has been anticipated by Nature, whether it be called
by the name of anchor, kedge, drag, or grapnel.
On the accompanying illustrations are shown a number of corresponding
forms of the Anchor, together with a few others, which, although they
may not necessarily be used in the water, are nevertheless constructed
on the same principle--_i.e._ for the purpose of grappling.
* * * * *
[Illustration: SPICULES OF SYNAPTA.]
[Illustration: ANCIENT ANCHOR.]
One of the most startling parallels may be seen on the right hand of the
illustration, the figure having been drawn from an old Roman coin. On
the other side of the same illustration may be seen an anchor so
exactly similar in form, that the outline of the one would almost answer
for that of the other. This object is a much-magnified representation of
a spicule which is found on the skin of the Synapta, one of the
so-called Sea-slugs, which are so extensively sold under the name of
Bêche de Mer. It forms one of the curious group called the Holothuridæ.
Each of these anchors is affixed to a sort of open-worked shield, as
shown above, and on the left hand; and it is a curious fact that in the
various species of Synapta the anchor is rather different in form, and
the shield very different in pattern. They are lovely objects, and I
recommend any of my readers who possess a microscope to procure one.
They need a power of at least 150 diameters to show their full beauties.
An ordinary Grapnel is here shown, and in the corresponding position on
the opposite side is an almost exactly similar object, except that it is
double, having the grapnel at both ends of the stem. This is a spicule
of a species of sponge, and is one of the vast numbers of which the
sponge principally consists.
[Illustration: LERNENTOMA.]
[Illustration: ECHINOCOCCUS.]
[Illustration: SPONGE-SPICULE.]
[Illustration: GRAPNEL.]
Next to the sponge-spicule is a still more perfect example of a natural
Grapnel. This is the head of an internal parasite called Echinococcus,
which holds itself in its position by means of the circle of hooks with
which the head is surrounded. These hooks are easily detached, and have
a curious resemblance to the claw of the lion or tiger.
On the left-hand side is a representation of a parasitic crustacean
animal called Lernentoma, which adheres to various fishes, and is mostly
found upon the sprat, clinging to the gills by means of its
grapnel-shaped head.
On the right hand of the accompanying illustration is an ice-anchor,
copied from one of those which were taken out in the Arctic expedition
of 1875. Opposite is the skull of the Walrus, the tusks of which are
said to be used for exactly the same purpose. Below are ice-hooks, also
used for the same expedition.
[Illustration: TUSKS OF WALRUS.]
[Illustration: ICE-ANCHOR AND ICE-HOOKS.]
The next illustration exhibits a butcher’s hook and a common porter’s
hook, by which he lifts sacks on his back; and opposite them are some
sponge-spicules, the similarity of which in form is so remarkable that
the former might have been copied from the latter.
[Illustration: SPONGE-SPICULES.]
[Illustration: BUTCHER’S HOOK.]
[Illustration: PORTER’S HOOK.]
* * * * *
[Illustration: MUSHROOM.]
[Illustration: MUSHROOM KEDGE.]
Our next sketch shows a remarkable example of similitude in form. There
are certain small anchors called Kedges, which are very useful for
mooring a boat where no great power of resistance has to be overcome,
and a large anchor would be cumbersome. One of these is called, from its
shape, the “Mushroom Kedge,” and is very useful, as, however it may be
dropped, some part of the edge is sure to take the ground. This Kedge is
shown on the right hand of the illustration, and the Mushroom, from
which its shape was borrowed, is seen on the left.
* * * * *
WE now come to some more examples of the principle of the Grapnel, some
of which are applied to nautical, and others to terrestrial objects.
[Illustration: EAGLE-CLAW.]
[Illustration: FLESH-HOOK.]
The right-hand upper figure represents the “Flesh-hook,” used for taking
boiled meat out of the caldron, so familiar to us by the reference to it
in Exodus xxvii. 3, and the still better-known allusion to its office in
1 Samuel ii. 13, 14. In the former passage, even the material, brass,
which was really what we now call bronze, is mentioned, and it is a
curious fact that all the specimens in the British Museum, from one of
which the drawing was taken, are made of bronze. I need hardly state
that the hollow handle is meant to receive a wooden staff.
On comparing this figure with that of the Eagle’s foot on the opposite
side, the reader cannot but be struck with the exact resemblance between
the two. Indeed, there is very little doubt that the flesh-hook was
intentionally copied from the foot of some bird of prey. Perhaps the
Osprey would have furnished even a better example than the Eagle, the
claws being sharper and more boldly curved, so as to hold their slippery
prey the better.
* * * * *
ON the left hand of the next illustration is a figure of the seed-vessel
of the Grapple-plant of Southern Africa, drawn from a specimen in my
collection. The seed-vessel is several inches in length, and the
traveller who is caught by a single hook had better wait for assistance
than try to release himself. The stems of the plant are so slender, and
the armed seed-vessels so numerous, that in attempting to rescue one
portion of the dress, another portion becomes entangled, and the
traveller gets hopelessly captured. Besides the hooks of the
seed-vessels, the branches themselves are armed with long thorns, set in
pairs. The scientific name of this plant is _Uncinaria procumbens_, the
former word signifying “a hook,” and the latter “trailing.” It is also
known by the popular name of Hook-plant.
[Illustration: GRAPPLE-PLANT.]
[Illustration: DRAG.]
In the late Kafir wars the natives made great use of this and other
plants with similar properties, their own naked, dark, and oiled bodies
slipping through them easily and unseen, while the scarlet coats of the
soldiers were quickly entangled, and made them an easy mark for the
Kafir’s spear. In this way many more of our soldiers were killed by the
spears than by the bullets of their enemies.
Opposite to the Grapple-plant is shown the common Drag, which is
utilised for so many purposes. Generally it is employed for recovering
objects that have sunk to the bottom of the water, and its use by the
officers of the Humane Society is perfectly well known, the Drag being
sometimes affixed to the end of a long pole, like the flesh-hook already
described, and sometimes tied to a rope.
It can also be used as an anchor, after the manner of a kedge, and has
been often employed in naval engagements for the purpose of drawing two
ships together, and preventing the escape of the vessel which is being
worsted. My relative, the late Admiral Sir J. Harvey, K.B., used drags
in this manner, and secured two French ships, one on either side,
namely, _L’Achille_ and _Le Vengeur_. The first was sunk, and the second
captured.
NAUTICAL.
CHAPTER V.
SUBSIDIARY APPLIANCES.
PART III.--THE BOAT-HOOK AND PUNT-POLE.--THE LIFE-BUOY AND PONTOON-RAFT.
The Boat-hook and its varied Uses.--The Earth-worm and the
Serpula.--Microscopic Boat-hooks.--The Life-belt.--Life-boats and
their Structure.--Uses of Cork.--Wine Corks made serviceable.--The
Life-collar.--Portuguese Man-of-war.--Captain Boyton’s
Life-dress.--The Life-raft.--Victualling a Yacht and Boat.--The
Janthina and its Air-vessels.--Cask-pontoon--Pottery-raft and its
Uses.
As all rowing men know, an indispensable appliance to the boat is the
Boat-hook, which can be used either as a pole, wherewith to push the
boat along, or as a grapnel, by which it can be drawn towards the shore
or a ship. As the latter portion has been discussed at the close of the
preceding chapter, we may proceed to the former.
Every one knows how a boat may be propelled by a pole pressed against
the bank or the bottom of the water, and that there are certain boats,
called punts, which are propelled in no other way.
Now, the punt-poles and boat-hooks, of which some examples are given in
the accompanying illustration, have long been anticipated in Nature,
there being many creatures which have no other mode of progression;
such, for example, as the common Earth-worm, which pushes itself along
by certain bristles which project from the rings of which the body is
composed, and which have the power of extension and contraction to a
wonderful extent. As, however, I shall advert to these in another part
of the work, I will content myself at present with a single example,
namely, the beautiful marine worm known as the Serpula.
This worm lives in a shelly tube, which is lined with a delicate
membrane, up and down which it passes with ease, ascending slowly, but
generally descending with such wonderful rapidity that the eye cannot
follow its movements. The latter movement will be explained in a
subsequent part of the book, and we will at present only treat of the
former.
[Illustration: PUSHING SPIKES OF SERPULA.]
[Illustration: BOAT-HOOKS AND PUNT-POLES.]
If the creature be removed from the tube, and carefully examined, a
number of projections will be seen, in each of which is a perforation.
If the animal be pressed, a slight glass-like bristle passes through the
perforation, and can easily be removed. If properly treated, and placed
under a high power of the microscope, the tiny bristle resolves itself
into the remarkable object which is shown on the left hand of the
illustration.
It consists of a number of spear-like rods, each having a straight
shaft, and a curved and pointed tip, deeply barbed on the inner portion
of the curve. These curious bundles of spicules can be protruded or
retracted at pleasure, and, as they are all directed backwards, it is
evident that when they are pushed against the sides of the tube, either
the points or the barbs must catch against the membrane which lines the
tube, and so propel the animal upwards. When it wishes to descend, it
uses another set of implements, and withdraws the first within their
sheaths.
This is exactly analogous to the mode of progression employed by
punters, who, after they have placed the pole against the bed of the
stream, and run along the punt so as to push it as fast as possible,
immediately withdraw the pole, and take it to the head of the punt,
ready for another push. This, as the reader will see, is exactly the
plan pursued by the Serpula in lengthening itself when it wishes to
advance, and so to press its spicules against the sides of its tube,
and in shortening itself and withdrawing the spicules ready for another
push.
* * * * *
ANOTHER needful accessory of vessels now comes before us, namely, the
capability of forming rafts or life-belts, which will float under any
circumstances. Here, again, every human invention of which I know has
been anticipated by Nature. Take, for example, the familiar instance of
the cork life-belt and the cork edgings of the life-boat. Both are
constructed on the same principle, _i.e._ the maintenance of cells which
are filled by air instead of water, and are impervious to the latter.
The material most used for this purpose is cork, and life-belts
constructed of it have long been in well-deserved use, the cork-bark
having the property of holding much air and excluding water. Many of our
life-boats are furnished with a broad and thick streak of cork, so that
even if the boat be filled with water and upset, she will right herself
and swim. I regret to say that many of the so-called “life-belts” which
are offered for sale ought rather to be called “death-belts,” they
having been found to be filled with hay and straw, with only a few
shavings of cork just under the covering of the belt.
Indeed, so buoyant is this substance that a very efficient belt can be
made by stringing together three or four rows of ordinary wine corks,
and tying them round the neck like a collar. Under these circumstances
it is simply impossible to sink, and though any one may collapse from
exhaustion, drowning is almost out of the question. The now well-known
cork mattress, which is used in many ships, is another example of the
same principle.
Lately there has been invented a “life-collar,” which possesses similar
advantages, but occupies less space when not wanted. It is nothing more
than a tube of caoutchouc, which can be inflated at pleasure, and tied
round the neck. The ordinary life-belt goes round the waist, and needs
much more material without obtaining a better result, which is simply
the keeping of the mouth and nostrils out of the water.
Perhaps the most buoyant of living beings is the Portuguese Man-of-war
(_Physalis pelagicus_), which floats on the surface of the ocean like a
bubble. It can at pleasure distend itself with air and float, or
discharge the air and sink.
Now, there is a very remarkable swimming dress, which, though not
entirely invented, was at least perfected by Captain Boyton, and which,
as it enabled the wearer to cross from France to England under rather
unfavourable circumstances, is clearly a most valuable invention.
[Illustration: PORTUGUESE MAN-OF-WAR.]
[Illustration: CAPTAIN BOYTON’S LIFE-DRESS.]
Whether the inventor knew it or not I cannot say, but the Boyton
life-dress is simply a modification of the Physalis, being capable of
dilatation with air at will.
* * * * *
SO much for the individual life-belt, and we will now pass to those
which are intended to sustain more than one individual. It has almost
invariably been found that when a ship has been wrecked on a rock, or
stove in by the sea, that, although there may be plenty of boats, there
is great difficulty in getting them into the water rightly.
Now, if parts of the ship itself could be made of materials which could
not be sunk except by enormous pressure, and which might be released by
a touch if the vessel were sinking, it is evident that many lives would
be saved which have now been lost.
And if such movable parts of the vessel were supplied with water and
provisions in air-tight cases, there is no doubt that the number of
“missing” ships would be very greatly diminished. I remember an instance
where a yacht was “hung up” on a mud-bank, whence there was no escape,
for twenty-four hours, and there was one sandwich on board to be divided
among the owner, two men, and a boy. Of course the boy had the sandwich,
and the men sustained themselves as well as they could with tea, of
which there was, fortunately, a canister on board. As it was, they were
some thirty-six hours without food.
After such an experience the owner had special lockers made in the yacht
and her boat, containing biscuit, potted meats, water, wine, spirits,
tobacco, tea, an “etna” for heating the water, and matches. Of course
these were on a smaller scale in the boat; but several thick rugs were
also stowed away, in case of being separated from the yacht at night. It
so happened that they were never needed; but the sense of security which
they imparted was worth ten times the expense and trouble, which
included a careful inspection of all the stores before each voyage.
In Nature there is just such a raft as is needed, capable of carrying a
heavy freight, and which cannot be upset. And it is rather remarkable
that it has been unconsciously imitated in various parts of the world.
[Illustration: JANTHINA AND AIR-RAFT.]
[Illustration: CASK-PONTOON. POTTERY-RAFT OF THE NILE.]
This is the singular apparatus attached to the Violet Snail (_Janthina
communis_), which is common enough in the Atlantic, and derives its name
of Violet-shell from its beautiful colour. The chief interest, however,
centres in the apparatus which is popularly called the “raft,” and which
sustains the shell and eggs. It is made of a great number of
air-vessels, affixed closely to each other, and by the curious property
of bearing its cargo slung beneath it instead of being laid upon it.
Beneath the raft are the eggs, or rather, the capsules which contain the
eggs, and at one end is the beautiful violet shell itself. The floating
power of the raft is really astonishing, and even in severe tempests,
when it is broken away from the animal, the raft continues to float on
the surface of the waves, bearing its cargo with it.
On the opposite side of the illustration are two examples of rafts
constructed so exactly on the same principle as that of the Violet
Snail, that they both might have been borrowed from it.
The upper is the kind of raft which has often been constructed by
sailors when trying to escape from a sinking ship, or by soldiers when
wishing to convey troops across a river, and having no regular
“pontoons” at hand. It is made simply by lashing a number of empty casks
to a flooring of beams and planks.
The amount of weight which such a structure will support is really
astonishing, as long as the casks remain whole, and to upset it is
almost impossible. Even cannon can be taken across wide expanses of
water in perfect safety, and there is hardly anything more awkward of
conveyance than a cannon, with its own enormous and concentrated weight,
and all the needful paraphernalia of limber, ammunition (which may not
be wetted, and of immense weight), horses, and men.
Yet even this heterogeneous mass of living and lifeless weight can be
carried on the cask-raft, which is an exact imitation of the living raft
of the Violet Snail.
* * * * *
BENEATH the cask-pontoon is to be seen a sketch of a very curious vessel
which is in use on the Nile, and I rather think on the Ganges also,
though I am not quite sure. It is formed in the following manner:--
In both countries there are whole families who from generation to
generation have lived in little villages up the river, and gained their
living by making pottery, mostly of a simple though artistic form, the
vessel having a rather long and slender neck, and a more or less
globular body.
When a man has made a sufficient number of these vessels, he lashes them
together with their mouths uppermost, and then fixes upon them a simple
platform of reeds. The papyrus was once largely used for this purpose,
but it seems to be gradually abandoned.
He thus forms a pontoon exactly similar in principle with the
cask-pontoon which has just been described. Then, taking his place on
his buoyant raft, he floats down the river until he comes to some
populous town, takes his raft to pieces, sells the pots and reeds, and
makes his way home again by land.
WAR AND HUNTING.
CHAPTER I.
THE PITFALL, THE CLUB, THE SWORD, THE SPEAR AND DAGGER.
Analogy between War and Hunting.--The Pitfall as used for both
Purposes.--African Pitfalls for large Game, and their Armature for
preventing the Escape of Prey.--Its Use in this Country on a
miniature scale.--Mr. Waterton’s Mouse-trap.--Pitfall of the
Ant-lion, and its Armature for preventing the Escape of Prey.--The
Club and its Origin.--Gradual Development of the Weapon.--The
“Pine-apple” Club of Fiji.--The Game of Pallone and the
“Bracciale.”--The Irish Shillelagh.--Clubs and Maces of Wood,
Metal, or mixed.--The Morgenstern.--Ominous Jesting.--Natural
Clubs.--The Durian, the Diodon, and the Horse-chestnut.--The Sword,
or flattened and sharpened Club.--Natural and artificial Armature
of the Edge.--The Sword-grass, Leech, and Saw-fish.--Spears and
Swords armed with Bones and Stones.--The Spear and Dagger, and
their Analogies.--Structure of the Spear.--The Bamboo as a Weapon
of War or Hunting.--Singular Combat, and its Results.
The two subjects which are here mentioned are practically one, the
warfare being in the one case carried on against mankind, and in the
other against the lower animals, the means employed being often the same
in both cases.
THE PITFALL.
One of the simplest examples of this double use is afforded by the
Pitfall, which is employed in almost every part of the world, and,
although mostly used for hunting, still keeps its place in warfare.
On the right hand of the accompanying illustration is shown a section of
the Pitfall which is so commonly used in Africa for the capture of large
game. It is, as may be seen, a conical hole, the bottom of which is
armed with a pointed stake. Should a large animal fall into the pit, the
shape of the sides forces it upon the stake, by which it is transfixed.
Even elephants of the largest size often fall victims to this simple
trap. It is only large enough to receive the fore-legs and chest, but
that is quite sufficient to cause the death of the animal, the stake
penetrating to the heart.
Many a hunter has fallen into these traps, and found great difficulty in
escaping, while some have not escaped at all. Indeed, in many parts of
Southern Africa, when part of one tribe is about to visit another, the
pitfalls are always unmasked, lest the intended guests should fall into
them.
[Illustration: PITFALL OF ANT-LION FOR CATCHING INSECTS.]
[Illustration: AFRICAN PITFALL FOR CATCHING LARGE GAME.]
Even without the spike, the elephant would scarcely be able to save
itself, owing to its enormous weight, unless helped out by its comrades
before the hunters came up. Indeed, many pitfalls are intentionally made
for this purpose, and are of a different shape, _i.e._ about eight feet
in length and four in breadth.
In those which are made for the capture of the giraffe, the pit is very
deep, and the place of the stake is occupied by a transverse wall, which
prevents the feet of the captive from touching the ground, and keeps it
suspended until the hunters can come and kill it at leisure.
Even in Belgium and our own country the pitfall is in use. When the
field-mice were devastating the districts about Liege some years ago,
their ravages were effectually checked by pitfalls, in which they were
caught by bushels, the pitfalls being simple holes some two feet deep,
and made wider below than above.
The late Mr. Waterton contrived to rid his garden of field-mice by
pitfalls constructed on the same principle, though more permanent.
Finding that the little animals made great havoc among his peas just as
they were starting out of the ground, he buried between the rows a
number of earthen pickle-jars, sinking them to the level of the ground.
He then rubbed the inside of the neck with bacon, and left them. The
mice stooped down to lick off the bacon, fell into the jars, and, the
neck being narrow and the sides slippery, they could not get out again.
* * * * *
ON the left hand of the illustration is the section of a pitfall made by
the well-known Ant-lion (_Myrmeleo_), of which there are several
species. The history of this wonderful insect is so familiar to us that
it need not be repeated at length. Suffice it to say that it digs
conical pitfalls in loose sandy soil, and that it places itself at the
bottom of the pit, securing the insect victims with its jaws just as the
larger animals are secured by the stake of the human hunter.
It makes no false cover, as does the human hunter, but it always chooses
soil so loose that if an insect approach the edge, the sand gives way,
and it goes sliding down into the pit, whence its chance of escape is
very small, even were there no deadly jaws at the bottom ready to
receive it.
THE CLUB.
The simplest of all offensive weapons is necessarily the CLUB. At first,
this was but a simple stick, such as any savage might form from a branch
of a tree by knocking off the small boughs with a stone or another
stick. Such clubs are still used in Australia, and I have several in my
collection.
Then the inventive genius of man improved their destructive power by
various means. The most obvious plan was to add to the force of its blow
by simply making one end much thicker and heavier than the other. This
is done in the “Knob-kerry” of Southern Africa, and it is worthy of
remark that in Fiji a weapon exists so exactly like the short knob-kerry
of Africa, that an inexperienced eye would scarcely be able to
distinguish between them.
The next plan was to arm the enlarged head with projecting pieces or
spikes, sometimes cut out of the solid wood, and sometimes artificially
inserted. The “Shillelagh” of Ireland is a simple example of this kind
of club. One of the best and most elaborate examples of this sort of
weapon is the “Pine-apple” Club of Fiji, a figure of which may be seen
in the illustration, drawn from a specimen in my collection.
It is made in the most ingenious manner from a tree which is trained for
the purpose. There are certain trees belonging to the palm tribe which
possess “aërial” roots, _i.e._ subsidiary roots, which surround the
trunk at some distance from the ground, and assist in supporting it.
Some trees have no central root, and are entirely upborne by the aërial
roots, while others have both.
One of these latter is selected, and when it is very young is bent over
and fastened to the ground almost at right angles, as shown in the
illustration. When it has grown to a sufficient age it is cut to the
requisite length, the central root is sharpened to a point, and the
aërial roots are also cut down in such a way that they radiate very much
like the projections on a pine-apple. This is really an ingenious
weapon, for if the long and sharpened end should miss its aim, the
projections would be tolerably sure to inflict painful if not
immediately dangerous injuries.
[Illustration: DURIAN.]
[Illustration: POLLEN OF HOLLYHOCK. HORSE-CHESTNUT.]
[Illustration: WOODEN AND METAL CLUBS.]
As the pine-apple is so well known, I have given in the opposite side of
the illustration a figure of the Durian, a large Bornean fruit, which is
covered with projections almost identical in appearance with those of
the pine-apple club, and almost equally hard and heavy.
Perhaps some of my readers may have heard of the grand Italian game of
Pallone, the “game of giants,” as it has been called. The ball, which
is a large and rather heavy one, weighing more than twice as much as a
cricket-ball, is struck with a wooden gauntlet reaching nearly half-way
up the fore-arm. The original gauntlet was cut entirely out of the solid
wood, and exactly resembled the exterior of the Durian. The modern
gauntlet, however, has the spikes fixed separately into a wooden frame,
so that they can be replaced if broken in the course of the game. The
principle, however, is identical in all three cases. The technical name
of this gauntlet is Bracciale.
The next improvement was to add still further to the destructive powers
of the club by arming it with stones, so as to make it harder and
heavier. Sometimes a stone is perforated, and the end of the club forced
into it. Sometimes the stone is lashed to the club, and sometimes a hole
is bored in the club, and the stone driven into it. This kind of club,
made of a sort of rosewood, may be found among some of the tribes
inhabiting the district of the Essequibo.
The next improvement was to make the weapon entirely of metal, and such
clubs are plentiful in every good collection of arms. There was, for
example, the common mace, which was used for the purpose of stunning an
adversary clothed in armour which the sword could not penetrate. As
this, however, was nothing more than an ordinary wooden club executed in
iron, we need not produce examples.
Other and more complicated forms were soon made, and were wonderfully
valuable until the rapidly improving firearms kept combatants at a
distance, and rendered a hand-to-hand fight almost impossible.
Three examples of such clubs are given in the illustration, and are
taken from Demmin’s valuable work called “Weapons of War.”
The upper left-hand specimen is called Morgenstern, _i.e._ Morning Star.
It is a large, heavy wooden ball studded with steel spikes, and affixed
to a handle usually some six or seven feet, but sometimes exceeding
eleven feet, in length. It was chiefly used by infantry when attacking
cavalry, the long shaft enabling the foot-soldier to be tolerably sure
of dealing the cavalier or his horse a severe blow, while himself out of
reach of the latter’s sword.
Behind it is another Morgenstern in which there is an improvement, the
armed ball being furnished at the end with a spike, so that it could be
used either as a mace or a spear.
The commonest form of the Morning Star is shown below, and is thus
described by Demmin:--
“This mace had generally a long handle, and its head bristled with
wooden or iron points. It was common among the ancients, for many
museums possess several fragments of these weapons belonging to the age
of bronze.
“The Morning Star was very well known and much used in Germany and
Switzerland. It received its name from the ominous jest of wishing the
enemy ‘good morning’ with the Morning Star when they had been surprised
in camp or city.
“This weapon became very popular on account of the facility and
quickness with which it could be manufactured. The peasants made it
easily with the trunk of a small shrub and a handful of large nails. It
was also in great request during the wars of the peasantry which have
devastated Germany at different times, and the Swiss arsenals possess
great numbers of them.”
One of these primitive weapons may be seen in the lower figure of the
illustration.
Sometimes the spiked ball was attached to a chain, and fastened to the
end of a handle varying greatly in length, measuring from two to ten
feet. One of these weapons may be seen in the Guildhall of London, being
held by one of the celebrated giants.
* * * * *
IF the reader will now turn to the illustration on page 53, he will see
that on the right of the Durian there are two spherical objects covered
with spikes. The upper is the pollen of the Hollyhock, and the lower the
common Horse-chestnut. The reader will see that these are precisely
similar in form to the spiked balls of the Morgenstern, whether they be
used at the end of a staff or slung to a chain. There are many similar
examples in the vegetable kingdom which will doubtless suggest
themselves to the reader, but these are amply sufficient for this
purpose.
Then, in the animal world, the curious Diodons, sometimes called
Urchin-fishes, or Prickly Globe-fishes, are good examples. These fishes
are covered with sharp spines, and, as they have the power of swelling
their bodies into a globular form, the spikes project on all sides just
like those of the pollen or chestnut. There is a specimen in my
collection, which, if the tail and fins were removed, and a cast taken
in metal, would make a very good Morgenstern ball.
THE SWORD.
The next improvement on the club was evidently to flatten it, and
sharpen one or both edges, so as to make it a cutting as well as a
stunning implement--in fact, the club was changed into a SWORD.
* * * * *
[Illustration: SWORD-GRASS MAGNIFIED.]
[Illustration: SHARK-TOOTH SWORD OF MANGAIA.]
A good example of this weapon in its simplest form is the wooden sword
of Australia, now an exceedingly rare weapon. It looks like a very large
boomerang, but is nearly straight, and is made from the hard, tough wood
of the gum-tree. Travellers say that the natives can cut off a man’s
head with this very simple weapon.
I just missed obtaining one of these swords from a man-of-war, but,
unfortunately, a few hours before my arrival the zealous first
lieutenant had ordered a large collection of savage weapons to be thrown
overboard, among which were several Australian swords.
Finding that the edges were not sufficiently sharp, and were liable to
break, the maker next turned his attention to arming them with some
substance harder than wood. Various materials were used for this
purpose, some of which will be mentioned.
One of these is given in the illustration, and is taken from a specimen
in my collection. It is made of wood, rather more than two feet in
length, and would in itself be an insignificant weapon but for its
armature.
This consists of a number of sharks’ teeth, which are fixed along either
side, and are a most formidable apparatus, each tooth cutting like a
lancet-blade, and not only being very sharp, but having their edges
finely notched like the teeth of a saw. I have a series of these weapons
in my collection, some being curved, some straight, and one very
remarkable weapon having four blades, one straight and long blade in the
centre, and three curved and short blades springing from the handle
towards the point.
Opposite the shark-tooth sword is an object which might almost be taken
for a similar weapon, but is, in fact, nothing but a common grass-blade,
such as may be found in any of our lanes. I suppose that most of my
readers must at some time have cut their fingers with grass, and the
reason why is shown in the illustration, which represents a
much-magnified blade of grass. The edges of the leaf are armed with
sharp teeth of flint, set exactly like those of the sword, with their
points directed towards the tip of the blade. The whole of the under
surface of the blade is thickly set with similar but smaller teeth,
arranged in the same manner. I have just brought a blade of grass from a
lane near my house, and when it was placed under the half-inch power of
the microscope, the resemblance to the sword was absolutely startling to
some spectators who came to look at it.
As if to make the resemblance closer, many savage weapons are edged with
flat stones, flint chips, or pieces of obsidian, so that the flint teeth
of the grass are exactly copied by the flint edgings of the sword. The
old Mexican swords were nearly all edged with obsidian, as is seen in
the lower right-hand figure of the next illustration. I possess a number
of obsidian flakes which were intended for that purpose, but do not
appear to have been used.
The second figure from the top represents the head of a spear similarly
armed, and I possess a small Australian implement in which the flakes of
obsidian are set only on one side, so that the instrument can be used as
a rude saw.
Between these two weapons is a spear-head armed with shark-teeth. I have
a very remarkable weapon of this kind, made in Mangaia. It is eleven
feet in length, and, besides being armed with a double row of sharks’
teeth nearly to the handle, it has three curved blades similarly armed,
set at distances of about two feet, and projecting at right angles.
Thus, if the foe were missed with the point of the spear, he would
probably be wounded by one of the blades.
[Illustration: SWORD-GRASS. LEECH JAW. SAW-FISH].
[Illustration: SPEARS AND SWORD ARMED WITH OBSIDIAN AND SHARKS’ TEETH.]
The upper figure represents a weapon where the natural bone of the
sting-ray has been used as the point.
On the opposite side are seen three natural objects similarly armed. The
uppermost is another species of sword-grass, like that which has already
been described.
Next comes a magnified view of one of the three cutting instruments of
the leech, showing the serrated teeth set along its edge, by means of
which it produces the sharply-cut wounds through which it sucks the
blood.
The last figure represents the head of the common Saw-fish, in which a
vast number of flat and sharply-edged teeth are set upon the blade-like
head. The fish has been observed to use this weapon just as the Mangaian
uses his sword-spear. It dashes among a shoal of fish, sweeps its head
violently backwards and forwards, and then, after they have dispersed,
picks up at its leisure the dead and disabled.
THE SPEAR AND THE DAGGER.
It is tolerably evident that the invention of the spear and dagger must
have been nearly, if not quite, contemporaneous with that of the club. I
place these weapons together because there is great difficulty in
assigning to either of them the precedence, the spear being but a more
or less elongated dagger, and the dagger a shortened spear.
As a good example of this fact, I have in my collection a number of
spears and daggers belonging to the Fan tribe of Western Africa. In
every case the weapons correspond so closely with each other, that if
the daggers were attached to shafts they would exactly resemble the
spears, and if the spears were cut off within a few inches of the head,
they would be taken for daggers.
I may here mention that as this part of the subject merely involves the
employment of a pointed or thrusting weapon, instead of the club or
sword, both of which are used for striking, the question of poison,
barbs, and sheaths will be treated on another page.
The primary origin of the Spear is probably the thorn, as a savage who
had been wounded by a thorn would easily pass to the conclusion that a
thorn of larger size would enable him to kill an enemy in war, or an
animal in hunting. Anything of sufficient dimensions, which either
possessed a natural point or could be sharpened into a point, would be
available for the purpose of the hunter or warrior.
Accordingly we find that such objects as the beak of the heron or stork,
the sharp hind-claw of the kangaroo, the bone of the sting-ray, the beak
of the sword-fish, and many similar objects, are employed for the heads
of spears, or used simply as daggers.
As to artificial spears, nothing is easier than to scrape a stick to a
point, and then, if needful, to harden it in the fire. This is, indeed,
one of the commonest forms of primitive spears, and I have in my
collection many examples of such weapons. Another simple form of this
weapon is that which is made by cutting a stick or similar object
diagonally.
Hollow rods--such, for example, as the bamboo--are the best for this
purpose. I have now before me a cast of a most interesting weapon
discovered by Colonel Lane Fox. It is the head of a spear, and is formed
from part of the leg-bone of a sheep. At one end there is a simple round
hole, which acted as a socket for the reception of the shaft, and the
other end is cut away diagonally, so as to leave a tolerably sharp
point.
As to the bamboo, it has a great advantage in the thinness of its walls,
and the coating of flinty substance with which it is surrounded, and
which gives its edges a knife-like sharpness. Indeed, so very sharp is
the silex, that splinters of bamboo are still used as knives, and with
them a skilful operator can cut up a large hog as expeditiously as one
of our pork-butchers could do with the best knife that Sheffield
produces.
I possess several of these weapons, and formidable arms of offence they
are. If the reader can imagine to himself a toothpick, a foot or more in
length, made from bamboo instead of quill, and having its edges nearly
as sharp as a razor, he can realise the force of even so simple a
weapon. In the case of the bamboo, too, celerity of manufacture has its
value, for any one can make a couple of spears in less than as many
minutes. All he has to do is to cut down a joint of bamboo transversely,
and then with a diagonal blow of his knife at the other end to form the
point.
The force of such a weapon may be inferred from a remarkable combat that
took place some sixty years ago, when the roads were not so safe as they
are at present.
A gentleman, who happened to be a consummate master of the sword, was
going along the highway at night, and was attacked by two footpads, he
having no weapon but a bamboo cane.
One of them he temporarily disabled by a severe kick, and then turned to
the other, whom he found to be pretty well as good a swordsman as
himself, and to possess a good stick instead of a slight cane. The
footpad soon discovered the discrepancy of weapons, and with a sharp
blow smashed the cane to pieces, leaving only about eighteen inches in
his antagonist’s hand.
Almost instinctively Baron ---- sprang under the man’s guard, and dashed
the broken cane in his face. The footpad staggered with a groan, put his
hands to his face, and ran away, followed by his companion, who did not
desire another encounter with such an antagonist. When the victor
reached his destination, he found that the footpad’s face must have been
torn to pieces, for the clefts of the split bamboo were full of scraps
of skin, flesh, and whisker hair.
It is worthy of notice that the combination of the club and the dagger
is common to savage and civilised life, as may be seen by reference to
the illustration in page 53, where the wooden club of savage warfare and
the metal club and maces of civilisation are alike armed with a piercing
as well as a bruising apparatus. Mostly the dagger is on the head of the
mace or battle-axe, but, in some cases, the end of the handle acts as
the dagger, and the head as the axe or mace.
A very good example of this formation is found in the wooden battle-axe,
or “Patoo,” of New Zealand, a weapon which has been long superseded by
modern fire-arms. A specimen in my possession is rather more than five
feet in length. The head is just like that of an ordinary axe, while the
handle tapers gradually to the end, where it terminates in a sharp
spike. In actual combat the point was used much more than the axe.
WAR AND HUNTING.
CHAPTER II.
POISON, ANIMAL AND VEGETABLE.--PRINCIPLE OF THE BARB.
Poison as applied to Weapons.--Its limited Use.--Animal and
Vegetable Poisons.--Animal Poisons.--The Malayan Dagger, or Kris,
and two Modes of poisoning it.--The Bosjesmans and their
Arrows.--Snake Poison and its Preparation.--The Pseudo-barb.--The
Poison-grub, or N’gwa.--Simple Mode of Preparation, and its
terrible Effects.--Vegetable Poisons.--The Upas of Malacca.--The
Wourali Poison of Tropical America.--Mode of preparing the various
Arrows.--The Fan Tribe of West Africa, and their poisoned
Arrows.--Subcutaneous Injection.--Examples in Nature.--The
Poison-fang of the Serpent.--Sting of the Bee.--Tail of the
Scorpion.--Fang of the Spider.--Sting of the Nettle.--Exotic
Nettles and their Effects.--The Barb and its Developments.--The
“Bunday” of Java.--Reversed Barbs of Western Africa.--Tongans and
their Spears.--The Harpoon and Lernentoma, or Sprat-sucker.--The
Main Gauche, or Brise-épée.
Another advance, if it may so be called, lay in increasing the deadly
effect of the weapons by arming them with poison.
Without the poison, it was necessary to inflict wounds which in
themselves were mortal; but with it a comparatively slight wound would
suffice for death, providing only that the poison mixes with the blood.
It is worthy of notice that cutting weapons, such as swords and axes,
seldom, if ever, have been envenomed, the poison being reserved for
piercing weapons, such as the dagger, the spear, and the arrow.
ANIMAL POISONS.
Perhaps the most diabolical invention of this kind was the Venetian
stiletto, made of glass. It came to a very sharp point, and was hollow,
the tube containing a liquid poison. When the dagger was used, it was
driven into the body of the victim, and then snapped off in the wound,
so that the poison was able to have its full effect.
Such poisons are of different kinds, and invariably animal or vegetable
in their origin. Taking the animal poisons first, we come to the curious
mode of poisoning the Malayan dagger, or “Kris.” The blade of the weapon
is not smooth, but is forged from very fibrous steel, and then laid in
strong acid until it is covered with multitudinous grooves, some of them
being often so deep that the acid has eaten its way completely through
the blade.
Among some tribes the kris is poisoned by being thrust into a putrefying
human body, and allowed to remain there until the grooves are filled
with the decaying matter. It is also said that if the kris be similarly
plunged into the thick stem that grows just at the base of the
pine-apple, the result is nearly the same.
As a rule, however, the Arrow is generally the weapon which is poisoned,
and a few examples will be mentioned of each kind of poisoning.
The two most formidable animal poisons are those which are made by the
Bosjesmans of Southern Africa. Their bows are but toys, and their arrows
only slender reeds. But they arm these apparently insignificant weapons
with poison so potent, that even the brave and bellicose Kafir warrior
does not like to fight a Bosjesman, though he be protected by his
enormous shield.
There are two kinds of animal poison used by the Bosjesmans. The first
is made from the secretion of the poison-glands of the cobra,
puff-adder, and cerastes. Knowing the sluggish nature of snakes in
general, the Bosjesman kills them in a very simple manner. He steals
cautiously towards the serpent, boldly sets his foot upon its neck, and
cuts off its head. The body makes a dainty feast for him, and the head
is soon opened, and the poison-glands removed.
By itself, the poison would not adhere to the point of the weapon, and
so it is mixed with the gummy juice of certain euphorbias, until it
attains a pitch-like consistency. It is then laid thickly upon the bone
point of the arrow, and a little strip of quill is stuck into it like a
barb. The object of the quill is, that if a man, or even an animal, be
wounded, and the arrow torn away, the quill remains in the wound,
retaining sufficient poison to insure death. I have a quiverful of such
arrows in my collection.
That arrows so armed should be very terrible weapons is easily to be
imagined, but there is another kind of poison which is even more to be
dreaded. This is procured from the innocent-looking, but most venomous,
Poison-grub. It is called N’gwa by the Bosjesmans, and is the larval
state of a small beetle. When the arrow is to be poisoned, the grub is
broken in half, and the juices squeezed upon the arrow in small spots.
Both Livingstone and Baines give full and graphic accounts of the
horrible effect produced by this dread poison, which, as soon as it
mixes with the blood, drives the victim into raging madness. A lion
wounded by one of these arrows has been known nearly to tear himself to
pieces in his agonies. M. Baines was good enough to present me with the
N’gwa grub in its different stages, together with an arrow which has
been poisoned with its juices.
The Bosjesmans are themselves so afraid of the weapon, that they always
carry the arrows with the points reversed, the poisoned end being thrust
into the hollow reed which forms the shaft of the arrow. Not until the
arrow is to be discharged does its owner place the tip with its point
uncovered.
VEGETABLE POISONS.
We now come to the Vegetable Poisons, the two best known of which are
the Upas poison of Borneo, and the Wourali of South America. It is
rather remarkable that in both these cases the arrows are very small,
and are blown through a hollow tube, after the manner of the well-known
“Puff-and-dart” toy of the present day.
The Upas poison is simply the juice of the tree, and it does not retain
its strength for more than a few hours after it has been placed on the
arrow-points. A supply of the same liquid is therefore kept in an
air-tight vessel made of bamboo, the opening being closed by a large
lump of wax kneaded over it at the mouth. One of these little flasks,
taken from a specimen in my collection, is seen on the extreme right of
the illustration.
The Wourali poison owes all its power to its vegetable element, though
certain animal substances are generally mixed with it. The principal
ingredient is the juice of one of the strychnine vines, which is
extracted by boiling, and then carefully inspissated until it is about
the consistency of treacle. This poison differs from the Upas in the
fact that it retains its potency after very many years, if only kept
dry. I have a number of arrows poisoned with the Wourali. They were
given to me by the late Mr. Waterton, who procured them in 1812, and
even in the present year (1875) they are as deadly as when they were
first made.
A bundle of these tiny arrows, surmounted by the little wheel which is
used to guard the hand from being pricked, is seen next to the Bornean
poison-flask.
[Illustration: SERPENT-FANG.]
[Illustration: BEE-STING.]
[Illustration: SCORPION-STING.]
[Illustration: NETTLE-STING.]
[Illustration: SPIDER-FANG.]
[Illustration: INJECTING SYRINGE.]
[Illustration: POISONED ARROWS AND POISON-FLASK.]
Beside these little arrows, which are only about ten inches in length,
very much larger arrows are used both for war and hunting, and are
propelled by the bow, and not with the breath. Many of these arrows are
nearly six feet in length. In all, the head is movable fitting quite
loosely into a socket, so that when an animal is struck and springs
forward, the shaft is shaken off, to be picked up by the hunter, and
fitted with another point, while the poisoned head remains in the wound.
Another kind of poison, also of a vegetable origin, is used by the Fan
tribe. The arrows are mere little slips of bamboo, and are propelled by
a slight crossbow. But the poison is so potent, that even these tiny
weapons produce a fatal effect.
Nearly in the centre of the illustration is seen a rather curiously
formed syringe, with an extremely long and slender tip. This is a
recently invented instrument, used for the purpose of subcutaneous
injection--_i.e._ of injecting any liquid under the skin. It is mostly
employed for injecting opium and other drugs of similar qualities, for
the purpose of obtaining relief from local pain. The slender spike-like
point is hollow, and ends in a sharp tip, formed like the head of a
lance. Just below the head there is a little hole, communicating with
the interior of the tube.
The mode of operating is simple enough. The syringe is filled with the
drug, and the point introduced under the skin at any given spot.
Pressure on the piston then forces out the liquid, and causes it to mix
with the blood.
NATURAL ANIMAL POISONS.
Now, both in the animal and vegetable worlds may be found several
examples of an apparatus which acts in exactly the same manner.
The first is the poison-fang of the Serpent, a specimen of which is
given on the left hand of the illustration. This fang answers in every
respect to the syringe above mentioned. The long and slender fang is
hollow, and answers to the pipe of the syringe. It communicates at the
base with a reservoir of liquid poison, which answers to the body of the
syringe, and there is a little hole, or rather slit, just above the
point, which allows the poison to escape.
When the serpent makes its stroke, the base of the fang is driven
against the reservoir, so that the liquid is urged through the hollow
tube, and forced into the wound. Even in large serpents these fangs are
very small. I have now before me some fangs of the cobra, puff-adder,
rattlesnake, and viper, and it is astonishing how small and slender are
these most deadly weapons. The figure in the illustration is much
magnified, in order to show the aperture at the base, where
communication is made with the interior of the fang. As the exit hole is
on the upper curve of the fang, it is not visible in the figure.
Next to the serpent’s fang is a representation of the Bee-sting, the
poisonous reservoir being seen at the base, and having attached to it
the tiny thread-like gland by which the poison is secreted.
In the centre is seen the tail of a Scorpion, with its hooked sting.
The last joint is formed just like the serpent’s fang, being hollow,
having a sharp point with a slit near the end, and a poison reservoir in
the rounded base. When the scorpion attacks an enemy, it strikes
violently with the tail, and the force of the blow drives out the poison
just as is done with the serpent’s fang.
At the bottom of the illustration is shown the poison-fang of a Spider,
which, as the reader may see, is formed just on the principle of the
scorpion-sting.
NATURAL VEGETABLE POISONS.
So much for animal poisons. We will now pass to the vegetable world.
Of the vegetable sting-bearers none are more familiar to us than the
Nettle, three species of which inhabit this country. The two commonest
are the Great Nettle (_Urtica diœcea_) and the Small Nettle (_Urtica
urens_), and both of them are armed with venomous stings, which cause
the plants to be so much dreaded.
The structure of these stings is very simple, and can be made out with
an ordinary microscope, or even a good pocket lens. Each of these stings
is, in fact, a rather elaborately constructed hair, hollow throughout
its length, coming to a point at the tip, and having the base swollen
into a receptacle containing the poisonous juice. When any object--such,
for example, as the human hand--touches a nettle, the points of the
stings slightly penetrate the skin, and the hair is pressed downwards
against the base, so that the poison is forced through the hole.
One of these hairs is shown in the left-hand bottom corner of the
illustration.
Even the tiny stings of our English nettles are sufficiently venomous to
cause considerable pain, and, in some cases, even to affect the whole
nervous system. But some of the exotic nettles are infinitely more
formidable, and are, indeed, so dangerous that, when they are grown in a
botanical garden, a fence is placed round them, so as to prevent
visitors even from touching a single leaf.
The two most dreaded species are called _Urtica heterophylla_ and
_Urtica crenulata_. The former is thought to be the more dangerous of
the two, and a good idea of its venomous qualities may be gathered from
an account of an adventure with _Urtica crenulata_. The narrator is M.
L. de la Tour.
“One of the leaves slightly touched the first three fingers of my left
hand; at the time I only perceived a slight pricking, to which I paid no
attention. This was at seven in the morning. The pain continued to
increase, and in an hour it became intolerable; it seemed as if some one
were rubbing my fingers with a hot iron. Nevertheless, there was no
remarkable appearance, neither swelling, nor pustules, nor inflammation.
“The pain spread rapidly along the arm as far as the armpit. I was then
seized with frequent sneezing, and with a copious running at the nose,
as if I had caught a violent cold in the head. About noon I experienced
a painful attack of cramp at the back of the jaws, which made me fear an
attack of tetanus. I then went to bed, hoping that repose would
alleviate my suffering, but it did not abate. On the contrary, it
continued nearly the whole of the following night; but I lost the
contraction of the jaws about seven in the evening.
“The next morning the pain began to leave me, and I fell asleep. I
continued to suffer for two days, and the pain returned in full force
when I put my hand into water. I did not finally lose it for nine days.”
There is another of these formidable nettles, called in the East by a
name which signifies “Devil’s Leaf,” and which is sufficiently venomous
to cause death. There is but little doubt, however, that in the present
instance, if a larger portion of the body--say the whole arm--instead of
three fingers, had been stung, death would have ensued from the injury.
THE BARB.
We now come to another improvement, or rather addition, in the various
piercing weapons. Sometimes, as in the case of the dagger or the
hand-spear, it was necessary that when a blow had been struck the weapon
should be easily withdrawn from the wound, so as not to disarm the
assailant, and to enable him to repeat the stroke if needful. But in the
case of a missile weapon, such as a javelin or an arrow, it was often
useful, both in war and hunting, to form the head in such a way that
when it had once entered it could scarcely be withdrawn. For this
purpose the Barb was invented, taking different forms, according to the
object of the weapon and the nationality of the maker.
As in this work I prefer to show the gradual development of human
inventions, I shall take my examples of barbs entirely from the weapons
of uncivilised nations, six examples of which are given in the
accompanying illustration, and five of them being drawn from specimens
in my collection.
[Illustration: BARBED WEAPONS.]
The upper left-hand figure is rather a curious one, the position of the
barbs being nearly reversed, so that they serve to tear the flesh rather
than adhere to it. The opposite figure represents an arrow with a doubly
barbed point. It is chiefly used for shooting fish as they lie dozing on
or near the surface of the water, but it is an effective weapon for
ordinary hunting purposes, and, as the shaft is fully five feet in
length, is quite formidable enough for war.
The left-hand bottom figure represents a very remarkable instrument, for
it can hardly be called a weapon, and is, in fact, the head of a
policeman’s staff. It is peculiar to Java, and is called by the name of
“Bunday.” As may be seen by reference to the illustration, the head of
the Bunday is formed of two diverging slips of wood. To each of these is
lashed a row of long and sharp thorns, all pointing inwards, and the
whole is attached to a tolerably long shaft.
When a prisoner is brought before the chief, a policeman stands behind
him, armed with the Bunday, and, if the man should try to escape, he is
immediately arrested by thrusting the weapon at him, so as to catch him
by the waist, neck, or arm, or a leg. Escape is impossible, especially
as in Java the prisoner wears nothing but his waist-cloth.
A weapon formed on exactly the same principle was used in the fifteenth
and sixteenth centuries, and was employed for dragging knights off
their horses. It was of steel instead of wood, and the place of the
thorns was taken by two movable barbs, working on hinges, and kept open
by springs. When a thrust was made at the knight’s neck the barbs gave
way, so as to allow the prongs to envelop the throat, and they then
sprang back again, preventing the horseman from disengaging himself.
This weapon is technically named a “catchpoll.”
An illustration of one of these weapons will be given on another page.
The right-hand central figure is an arrow from Western Africa. In a
previous illustration (page 65) a head of one of these arrows is given
on rather a larger scale, so as to show the very peculiar barbs. These
are of such a nature that when they have well sunk into the body they
cannot be withdrawn, but must be pushed through, and drawn out on the
opposite side. This is drawn from one of my own specimens.
In some cases, with an almost diabolical ingenuity, the native
arrow-maker has set on a couple of similar barbs, directed towards the
point, so that the weapon can neither be pushed through nor drawn back.
One of these arrows is shown in the illustration, but, for want of
space, the artist has placed the opposing barbs too near each other.
In some parts of Southern Africa a similar weapon was used for securing
a prisoner, the barbed point being thrust down his throat and left
there. If it were pushed through the neck it killed him on the spot, and
if it remained in the wound the man could not eat nor drink, and the
best thing for him was to die as soon as he could.
With similar ingenuity, the Tongans and Samoans made their war-spears
with eight or nine barbs, and, before going into action, used to cut the
wood almost through between each barb, so that when the body was
pierced, the head, with several of the barbs, was sure to break off and
leave a large portion in the wound. In Mariner’s well-known book there
is an admirable account of the mode employed by a native surgeon for
extracting one of these spear-heads. So common was this weapon that
every Tongan gentleman carried a many-barbed spear about five feet long,
and used it either as a walking-stick or a weapon. It is needless to say
that this spear is almost an exact copy of the tail-bone of the
Stingray. A dagger made of this bone was used in the Pelew Islands in
1780, but seemed to be rather scarce.
The left-hand central figure is a Fijian fish-spear of four points, and
the last figure on the right hand represents a large four-pronged spear
of Borneo. Both these weapons are in my collection.
* * * * *
ANOTHER example of a weapon where a large and powerful barb is needful
is the Harpoon. As the harpoon is used in capturing the whale, the
largest and most powerful of living mammalia, it is evident that a barb
which will hold such a prey must be rather peculiarly made. The head and
part of the shaft of the harpoon are shown in the right-hand figure of
the accompanying illustration.
[Illustration: LERNENTOMA.]
[Illustration: HARPOON.]
The left-hand figure represents a curious parasitic crustacean,
popularly called the Sprat-sucker, because it is usually found on
sprats. It affixes itself mostly to the eye, the deeply barbed head
being introduced between the eye and the socket. In some seasons this
remarkable parasite is quite plentiful, while in others scarcely a
specimen can be found. Its total length is slightly under an inch, and
its scientific name is _Lernentoma Spratti_.
The following graphic account of some prototypic weapons belonging to a
marine worm is given by Mr. Rymer Jones, and is well worthy of perusal,
not only for the vividness of the description, but for its exact
accuracy:--
“Here is a Polynoe, a curious genus, very common under stones at low
water on our rocky shores.
“It is remarkable on several accounts. All down the back we discover a
set of oval or kidney-shaped plates, which are called the back-plates
(_dorsal elytra_); these are flat, and are planted upon the back by
little footstalks, set on near the margin of the under surface: they are
arranged in two rows, overlapping each other at the edge. These
kidney-shaped shields, which can be detached with slight violence, are
studded over with little transparent oval bodies, set on short
footstalks, which are, perhaps, delicate organs of touch. The
intermediate antennæ, the tentacles, and the cirrhi or filaments of the
feet, are similarly fringed with these little appendages, which resemble
the glands of certain plants, and have a most singular appearance.
“If we remove the shields, we discover, on each side of the body, a row
of wart-like feet, from each of which project two bundles of spines of
exquisite structure. The bundles, expanding on all sides, resemble so
many sheaves of wheat, or you may more appropriately fancy you behold
the armoury of some belligerent sea-fairy, with stacks of arms enough to
accoutre a numerous host.
“But, if you look closely at the weapons themselves, they rather
resemble those which we are accustomed to wonder at in missionary
museums,--the arms of some ingenious but barbarous people from the South
Sea Islands,--than such as are used in civilised warfare. Here are long
lances, made like scythe-blades, set on a staff, with a hook on the tip,
as if to capture the fleeing foe, and bring him within reach of the
blade. Among them are others of similar shape, but with the edge cut
into delicate slanting notches, which run along the sides of the blade
like those on the edge of our reaping-hooks.
“These are chiefly the weapons of the lower bundle; those of the upper
are still more imposing. The outermost are short curved clubs, armed
with a row of shark’s teeth to make them more fatal; these surround a
cluster of spears, the long heads of which are furnished with a double
row of the same appendages, and lengthened scimitars, the curved edges
of which are cut into teeth like a saw.
“Though a stranger might think I had drawn copiously on my fancy for
this description, I am sure, with your eye upon what is on the stage of
the microscope at this moment, you will acknowledge that the
resemblances are not at all forced or unnatural. To add to the effect,
imagine that all these weapons are forged out of the clearest glass
instead of steel; that the larger bundles may contain about fifty, and
the smaller half as many each; that there are four bundles upon every
segment, and that the body is composed of twenty-five such segments, and
you will have a tolerable idea of the garniture and armature of this
little worm, which grubs about in the mud at low-water mark.”
[Illustration: PART OF WASP-STING.]
[Illustration: MAIN GAUCHE.]
Somewhere between the fifteenth and sixteenth centuries a sort of
anomalous weapon was in use, namely, a dagger, with a number of very
deep and bold barbs. It was not, however, employed for offence, but for
defence, and was used in the “rapier and dagger” mode of fighting, when
the dagger, which was held in the left hand, was employed to parry the
thrusts of the rapier, which was held in the right. From the mode of
holding it, the weapon was called “Main Gauche.”
Sometimes the blade was quite plain, and, indeed, an ordinary dagger
answered the purpose. But in most cases the Main Gauche was made for
this special purpose, and was furnished either with strong diverging
projections, or with a series of deep notches, so that the sword of the
enemy might be caught in them and broken. In consequence of this use
these notched or guarded weapons were also called by the name of
_Brise-épée_, or Sword-breaker.
The resemblance between this weapon and the blade of a wasp’s sting can
be seen at a glance. There is another form of the _Brise-épée_ which is
so strangely like the cutting apparatus of one of the saw-flies, that an
outline sketch of the one would answer very well for the other.
WAR AND HUNTING.
CHAPTER III.
PROJECTILE WEAPONS AND THE SHEATH.
Propulsive Power.--The Pea-shooter and its Powers.--An Attack
repulsed.--Clay Bullets.--Puff and Dart.--The Sumpitan of Borneo,
and its Arrows.--The Zarabatana or Pucunha of South America, and
its Arrows.--The Air-gun.--Modern Firearms.--The Chœtodon, or
Archer-fish.--The Pneumatic Railway.--The Throwing-stick and its
Powers.--Australians, Esquimaux, and New Caledonians.--Principle of
the Sheath.--Waganda Spears.--Sheathed Piercing Apparatus of the
Gnat, Flea, and Bombylius.--Indian Tulwar and Cat’s Claw.--The
Surgeon’s Lancet, and Piercing Apparatus of the Gad-fly and
Mosquito.
We will now take some of the analogies between Projectile Weapons of Art
and Nature, selecting those in which the propulsive power is air or
gases within a tube. Whether the weapon be a blow-gun, an air-gun, or a
firearm of any description, the principle is the same. We will take them
in succession, choosing first those of the simplest and most primitive
character.
Taking ourselves as examples, and looking upon the toys of children as
precursors of more important inventions, we find that the simplest and
most primitive of projectiles is the Pea-shooter, so familiar to all
boys.
Insignificant as is the little tin tube, and small as are the missiles
which are propelled through it, the blow which can be struck by a pea
properly shot is no trifle. At college I have seen a night attack upon
an undergraduate’s rooms successfully repelled by a pea-shooter made for
the nonce of a glass tube, the owner of the rooms having a taste for
chemicals, and possessing a fair stock of the usual apparatus. Though
the assaulted rooms were on the top set, and the assailants began their
storming approaches below, the peas were too much for the stones,
taking stinging effect on the hands and faces, and preventing any good
aim being taken at the windows. Only two panes of glass were broken
through a siege that lasted for several hours.
There is another toy which is a development of the pea-shooter, and
carries a small clay bullet instead of a pea. When the tube is quite
straight and the balls fit well, the force of this missile is very
great, as it can be used for killing small birds. Indeed, such an
instrument is largely employed by the native hunters in procuring
humming-birds for the European market. These weapons are generally lined
with metal in this country, but a simple bamboo tube is sufficient for
the native hunters.
A still further improvement occurs where the place of the bullet is
taken by a small dart or arrow, which is usually made to fit the bore by
having a tuft of wool, or some similar substance, at the butt. The arrow
is aimed at a target, and the toy is popularly known as “Puff and Dart.”
With us this apparatus is only a toy, but in several parts of the world
it becomes a deadly weapon, namely, in Borneo and over a large part of
tropical America. In both cases the arrows are poisoned, as has already
been mentioned when treating of poisoned weapons.
* * * * *
THE first and best known of these weapons is the dreaded Sumpitan, or
Blow-gun, of Borneo, the arrows of which are poisoned with the deadly
juice of the upas-tree. Here I may as well mention that the scientific
name of the upas-tree is _Antiaris toxicaria_. It belongs to a large
group of plants, all of which have an abundance of milk-like and
sometimes poisonous juice. We are most of us familiar with the old story
of the upas-tree and its deadly power, and how the tree stood in a
valley, in which nothing else could live, and that condemned criminals
might compound for their inevitable fate by venturing into the valley of
death and bringing back a flask of the dread poison. Even birds were
supposed to be unable to fly over the valley, but to fall into it, being
poisoned by the exhalations of the tree.
Now, there is a saying that there is no smoke without fire, and though
this account is evidently incredible, it is not altogether without
foundation. In Java, as in many other parts of the world, there are
low-lying places where carbonic acid gas exudes from the earth, and no
living creature can exist in them. Even in this country scarcely a year
passes without several deaths occurring from inhalation of the same
fatal gas, which has collected in some disused excavation. That there
is, therefore, a deadly valley in Java may be true enough, and it is
also true that the juice of the upas-tree is poisonous when it mixes
with the blood. But the two have no connection with each other, and, so
far from the upas-tree poisoning the valley by its exhalations, it could
not exist in such an atmosphere.
Now for the Sumpitan and the arrows. The former is a tube, some seven
feet in length, with a bore of about half an inch in diameter, and often
elaborately inlaid with metal. I have one in which the whole of the
mouthpiece is brass, and the other end of the weapon has been fitted
with a large spear-head, exactly on the principle of the bayonet.
The arrows are very slight, and, in order to make them fit the tube, are
furnished at their bases with a conical piece of soft wood. In
themselves they would be almost useless as weapons, but when the poison
with which their points are armed is fresh, these tiny arrows, of which
sixty or seventy are but an ordinary handful, carry death in their
points. Though they have no great range, they are projected with much
force, and with such rapidity that they cannot be avoided, their slender
shafts being almost invisible as they pass through the air.
* * * * *
THE second weapon is the still more dangerous blow-gun of tropical
America, called Zarabatana, or Pucunha, according to the locality. Some
of these tubes measure more than eleven feet in length, and through them
the arrow can be propelled with wonderful force. I have often sent an
arrow to a distance of a hundred yards, and with a good aim.
A native, however, can send it much farther, knack, and not mere
capacity of lung, supplying the propelling power, just as it is with the
pea-shooter. When the arrow is properly blown through the zarabatana a
sharp “pop” ought to be heard, like the sound produced by a finger
forced into a thimble and quickly withdrawn, or a cork drawn from a
bottle.
As to seeing the diminutive arrow in its flight, it is out of the
question, and no agility can be of the least use in avoiding it. One of
my friends, a peculiarly sharp-sighted officer of artillery, has often
tested this point, and although there was but one arrow to watch, and it
was blown in the open air, he could not see it until it either struck or
passed him (of course the poisoned end was cut off). What, then, would
be the result of a number of these deadly missiles hurled out of a dense
bush may easily be imagined.
An account of the poison with which these arrows are armed will be found
on p. 64.
* * * * *
THE reader will please to remember that in all these cases the missile
is propelled by air which is compressed by the aid of the lungs, and
forced into the tube behind the bullet or arrow. Now, the AIR-GUN, which
really can be made a formidable weapon, is constructed on exactly the
same principle as the pea-shooter and the blow-guns, except that the air
is compressed by the human arm instead of the human lungs. There are
various modifications of this weapon, but in all of them air is driven
into a strong chamber by means of a forcing syringe, and is released by
the pull of the trigger, so as to drive out the missile which has been
placed in the barrel.
It is worthy of notice that the term “noiselessly destructive” weapon,
as applied to the air-gun, is entirely false. I have already mentioned
that with the blow-gun of tropical America a definite explosion
accompanies the flight of each arrow. The same result occurs with the
air-gun, the loudness of the report being in exact proportion to the
force of the air, each successive report becoming slighter and the
propulsive power weaker until a new supply of air is forced into the
chamber.
* * * * *
HOWEVER dissimilar in appearance may be the cannon, rifle, pistol, or
any other firearm, to the pea-shooter and its kin, the principle is
exactly the same in all. It has been already mentioned that in the
blow-guns the air is compressed by the exertion of human lungs, and in
the air-gun the compression is achieved by human hands.
But with the firearm a vast volume of expansible gas is kept locked up
in the form of gunpowder, gun-cotton, fulminating silver, or other
explosive compound, and is let loose, when wanted, by the aid of fire.
* * * * *
[Illustration: CHŒTODON, OR ARCHER-FISH.]
[Illustration: BLOW-GUNS--CANNON.]
In the illustration are represented on the right hand the blow-guns of
America and Borneo, and below them is the cannon as at present made. On
the left hand of the same illustration is seen a representation of a
natural gun which has existed for thousands of years before gunpowder
was invented, and very long before the savage of Borneo or America
discovered the blow-gun.
It is the ARCHER-FISH (_Chœtodon_), which possesses the curious power
of feeding itself by shooting drops of water at flies, and very seldom
failing to secure its prey.
There are several species of this very curious fish spread over the
warmer parts of the world, and their remarkable mode of obtaining prey
is very well known in all. There is, indeed, scarcely any phenomenon in
Nature more remarkable than the fact of a fish being able to shoot a fly
with a drop of water projected through its tubular beak, if we may use
that expression for so curiously modified a mouth.
Indeed, so certain is the fish of its aim, that in Japan it is kept as a
pet in glass vases, just as we keep gold fish in England, and is fed by
holding flies or other insects to it on the end of a rod a few inches
above the surface of the water. The fish is sure to see the insect, and
equally sure to bring it down with a drop of water propelled through its
beak.
It is worthy of remark that the same principle was once, though
unsuccessfully, employed in the propulsion of carriages, under the name
of the Pneumatic Railway. Some of my readers may remember the railway
itself, or at all events the disused tubes which lay for so many years
along the Croydon Railway. Speed was obtained, as I can testify from
personal experience, but the expense of air-pumps and air-tight tubing
was too great to be covered by the income, especially as the rats ate
the oiled leather which covered the valves.
* * * * *
I FIND some little difficulty in arranging the subject which comes next
in order. It might very properly be ranked among the Levers, which will
be treated of in another chapter; or it might be placed among the
examples of centrifugal force, together with the sling, the “governor”
of the steam-engine, &c., all of which will be more fully described in
their places. However, as we are on the subject of Projectiles, we may
as well take it in the present place.
It is the THROWING-STICK, by which the power of the human arm is
enormously increased, when a spear is to be hurled. Perhaps the most
expert spear-throwers in the world are to be found among the Kafir
tribes of Southern Africa, and yet the most experienced among them could
not make sure of hitting a man at any distance above thirty or forty
yards. But the throwing-stick gives nearly double the range, and I have
seen the comparatively slight and feeble Australian hurl a spear to a
distance of a hundred yards, and with an aim as perfect as that of a
Kafir at one-fourth of the distance.
The mode in which this feat is performed is shown in the accompanying
diagram. Instead of holding the spear itself, the native furnishes
himself with a “Throwing-stick.” This weapon varies greatly in shape and
size, but a very good idea of its form, and the manner of using it, may
be obtained from the accompanying illustration, which was drawn from the
actual specimen as held by an Australian native.
The throwing-stick is armed at the tip with a short spike, which fits
into a little hole in the but of the spear. The stick and spear being
then held as shown in the illustration, it is evident that a powerful
leverage is obtained, varying according to the length of the stick. I
possess several of these instruments, no two of which are alike.
It is rather remarkable that among the Esquimaux a throwing-stick is
also used, exactly similar in principle, but differing slightly in
structure, the but of the spear fitting into a hole at the end of the
throwing-stick. Wood being scarce among the Esquimaux, these
instruments are mostly made of bone. I possess one, however, which is
made of wood, beautifully polished, and adorned with a large blue stone,
something like a turquoise, set almost in its middle. One of the most
curious points in the formation of the Esquimaux weapon is, that the but
is grooved and channelled so as to admit the fingers and thumb of the
right hand. The average length of this instrument is twenty inches.
[Illustration: JAW OF SNAKE.]
[Illustration: THROWING-STICK.]
* * * * *
IN New Caledonia the natives use a contrivance for increasing the power
of the spear, which is based on exactly identical principles, though the
mode of carrying them out is different. A thong or cord of some eighteen
inches in length is kept in the right hand, one end being looped over
the forefinger, and the other, which is terminated by a button, being
twisted round the shaft of the spear. When the weapon is thrown, the
additional leverage gives it great power; and it is a noteworthy fact
that the sling-spear of New Caledonia has enabled us to understand the
otherwise unintelligible “amentum” of the ancient classic writers.
* * * * *
PASSING from Art to Nature, we have in the jaw of the serpent an exact
type of the peculiar leverage by which the spear is thrown. If the
reader will refer to the illustration, he will see that the lower jaw of
the snake, instead of being set directly on the upper jaw, is attached
to an elongated bone, which gives the additional leverage which is
needful in the act of swallowing prey, after the manner of serpents.
* * * * *
IN War and in Peace we have been long accustomed to shield the edges and
points of our sharp weapons with sheaths, and even the very savages have
been driven to this device. I have in my collection a number of
sheathed weapons from nearly all parts of the world, and it is a
remarkable fact that the Fan tribe, who are themselves absolutely naked,
sheathe their daggers and axes as carefully as we sheathe our swords and
bayonets. In some points, indeed, they go beyond us; for the most
ignorant Fan savage would never think of blunting the edge of his weapon
by sheathing it in a metal scabbard. Their sheaths are beautifully made
of two flat pieces of wood, just sufficiently hollowed to allow the
blade to lie between them, and bound together with various substances.
For example, the sheaths of one or two daggers in my possession are made
of wood covered with snake-skin, while others are simply wood bound with
a sort of rattan. Even the curious missile-axe which the Fan warrior
uses with such power is covered with a sheath when not in actual use.
[Illustration:
PIERCING APPARATUS AND SHEATHS. SHEATHED SPEARS OF WAGANDA.
GNAT. FLEA. BOMBYLIUS.]
The figure on the right hand of the illustration represents the heads of
two spears of Waganda warriors. When they present themselves before
their king, the warriors must not appear without their weapons, and it
would be contrary to all etiquette to show a bare blade except in
action. The sheath can be slipped off in a moment, but there it is, and
any man who dared to appear before his sovereign without his weapon, or
with an unsheathed spear, would lose his life on the spot, so exact is
the code of etiquette among these savages.
The sheathed spears of Nature are shown in the same illustration. On the
left is a side view of the piercing apparatus of the common Gnat.
In the middle is the compound piercing apparatus of the common Flea,
with which we are sometimes too well acquainted, the upper figure
showing the lancets and sheaths together, and the lower exhibiting them
when separated.
On the right is shown the group of mouth-lancets belonging to one of the
Humble-bee flies (_Bombylius_). These flies do not suck blood like the
Mosquito, the Flea, and the Gad-fly, but they use the long proboscis for
sucking the sweet juices out of flowers, and in consequence it is nearly
of the same form as if it were meant for sucking blood. Indeed, there
are some insects which do not seem to care very much whether the juice
which they suck is animal or vegetable.
[Illustration: 8 CLAW.--SHEATH OPENING ALONG THE CURVED BACK.]
[Illustration: INDIAN TULWAR.--SHEATH OPENING ALONG THE CURVED BACK.]
On the right hand of the illustration is seen an Indian sword, or
“Tulwar,” drawn from one of my own specimens. I have selected this
example on account of the structure of the sheath. It is evident, from
the form of the blade, that the sword cannot be sheathed point foremost,
and that therefore some other plan must be used. In this weapon the
sheath is left open on one side, the two portions being held together by
the straps which are shown in the figure. Of course there is loss of
time in sheathing and drawing such a sword, but the peculiar shape of
the blade entails a necessity for a special scabbard.
On the other side is shown one of the fore-claws of a cat, which, as we
all know, can be drawn back into its simple sheath between the toes,
when it is not in use. This sheath is exactly the same in principle as
that of the Indian tulwar, and any one can examine it by looking at the
foot of a good-tempered cat. I have done so even with a chetah, which is
not a subject that would generally be chosen for such a purpose.
On the next illustration is shown an ordinary Lancet, in which the blade
is guarded between a double sheath, the two halves and the blade itself
working upon a common pivot. As for the ordinary sword and dagger
sheaths, it is not worth while to figure them.
* * * * *
TURNING to the opposite side of the illustration, we shall see a few of
the innumerable examples in which the principle of the sheath was
carried out in Nature long before man came on the earth.
The reader should compare this figure with the side view of the Gnat’s
lancets given on p. 81.
[Illustration: LANCETS OF TABANUS
CLOSED.]
[Illustration: LANCETS OF MOSQUITO
PARTLY OPEN.]
[Illustration: SURGEON’S LANCET
PARTLY OPEN.]
They represent the cutting and piercing instruments of several insects,
all of which are very complicated, and are sheathed after the manner of
the lancet. Indeed, they are popularly known as “mouth-lancets,” and
with reason, as the reader may see by reference to the illustration.
On the extreme left are shown the head and closed lancets of a foreign
Gad-fly, the lancets being all in their sheaths, and showing the
character of the weapon which enables a small fly to be master, or
rather mistress, of the forest. I say mistress, because in all these
cases it is the female alone that possesses these instruments of
torture.
Next it is a magnified representation of the lancets of the common
Mosquito, as seen from above, both lancets being removed from their
sheaths and separated.
WAR AND HUNTING.
CHAPTER IV.
The Net, as used in Hunting and War.--The Seine-net, as used for
Fishing.--Also as a means of Hunting.--Net for
Elephant-catching.--Steel Net for Military Purposes.--Web of the
Garden Spider.--The Casting-net, as used in Fishing.--Also as
employed in the Combats of the ancient Circus.--Various Kinds of
Casting-nets.--The Argus Star-fish and the Barnacle.--The Rod and
Line.--Angling of various Kinds.--The Polynesian as an Angler.--The
Angler-fish.--“Playing” a Fish.--The Nemertes and its Mode of
Feeding.--Mr. Kingsley’s Account of it.--Power of Elongation and
Contraction.--The Cydippe.--Spring-traps.--The Gin, Rat-trap, and
Man-trap.--Jaws of Dolphin, Porpoise, and Alligator.--Legs of
Phasma.--Baited Traps.--Carnivorous Plants and their Mode of
Feeding.--Birdlime.--“Pegging” for Chaffinches.--Curious Mode of
Tiger-killing.--Ant-eater and its Mode of Feeding.--The
Drosera.--Web of Spider and its Structure.
THE NET.
Although the Net is but seldom employed for the purposes of general
warfare, it was once largely used in individual combats, of which we
will presently treat. In hunting, however, especially in fishing, the
Net has been in constant use, and is equally valued by savages and the
most civilised nations.
To begin with the fisheries. Even among ourselves there are so many
varieties of fishing-nets that even to enumerate them would be a work of
time. However, they are all based on one of two principles, _i.e._ the
nets which are set and the nets which are thrown.
We will begin with the first.
* * * * *
ON the right hand of the illustration, and at the bottom, may be seen a
common Seine-net being “shot” in the sea. This form of net is very long
in proportion to its width, some of these nets being several miles long.
The upper edge of the net is furnished with a series of cork bungs,
which maintain it on the surface, while the lower edge has a
corresponding set of weights, which keep the net extended like a wall of
meshes. Any fish which come against this wall are, of course, arrested,
and are generally caught by the gill-covers in their vain attempts to
force themselves through the meshes.
We may see representations of fishing with the seine-net in the
sculptures and paintings of Egypt and Assyria; and in the Berlin Museum
there is a part of an Egyptian seine-net with the leads still upon the
lower edge, and the upper edge bearing a number of large pieces of wood,
which acted as buoys, and served the same purpose as our corks.
[Illustration: SPIDER-WEB. HUNTING-NET. THE SEINE-NET.]
* * * * *
IN hunting, this plan has been adopted for many centuries, the upper
edge of the net being supported on poles, and the lower fastened to the
ground in such a manner as to leave the net hanging in loose folds.
While this part of the business is being completed by the servants, the
hunters are forming a large semicircle, in which they enclose a number
of wild beasts, which they drive into the nets or “toils” by gradually
contracting the semicircle. The ancient sculptures give us accounts of
nets used in exactly this manner. There are represented the nets rolled
up ready for use, and being carried on the shoulders of several
attendants, who are bearing them to the field. Then there are the nets
set up on their poles, and having enclosed within them a number of wild
animals, such as boars and deer.
In various parts of India, hunting with the net is one of the chief
amusements of their principal men, and the variety of game driven into
the toils is really surprising, and affords a magnificent sight to those
who view it for the first time. Even the tiger himself cannot leap over
the nets because they are so high, nor force his way through them,
because their folds hang so lightly that they offer no resistance to his
efforts.
A very simple net on similar principles is used for catching elephants.
It is formed of the long creeping plants that fling themselves in
tangled masses from tree to tree. These creepers are carefully twisted
into a net-like form, without being removed from the trees, and when a
sufficient space has been enclosed the elephants are driven into it. Not
even their gigantic strength and tons of weight are capable of breaking
through a barrier which, apparently slight, is as strong as if it were
built of the tree-trunks on which the creepers are hung.
This net is seldom used for military purposes, though I have seen one,
which I believe still exists, and would do good service. In one of our
largest fortresses there is a subterranean corridor, through which it is
desirous that the enemy should not penetrate. One mode of defence
consists of a large net made of steel hanging loosely across it. The
meshes are about ten inches square, so that the defenders can fire from
their loopholes through the meshes, while the assailants, even if they
knew of its position, would find that nothing smaller than a field-gun
would have any effect on this formidable net.
* * * * *
THE natural analogy of the fixed net is evidently the web of the common
Garden Spider, or Cross Spider (_Epeira diadema_), whose beautiful nets
we all must have admired, especially when we are wise enough to get up
sufficiently early in the morning to see the webs with the dewdrops
glittering on them.
Last year there was a wonderful sight. Within a mile of my house there
is a long iron fence, which in one night had been covered with the webs
of the garden spider. The following morning, though bright, was chilly,
so that the dewdrops were untouched. I happened to pass by the fence
soon after sunrise, and was greatly struck with the astonishing effects
which could be produced with such simple materials as water and web. The
dewdrops were set at regular intervals upon the web, so as to produce a
definite and beautiful pattern, the whole line of fence looking as if
it had been woven in fine lace.
Then, as the fence runs north and south, and the path is on the westward
of it, every passenger saw the rays of the rising sun dart through these
tiny globules, and convert every one of them into a jewel of
ever-changing colours. It seemed a pity that such beauty could but last
for an hour or so, or that these exquisite webs should only be used for
catching flies.
* * * * *
NEXT comes the Casting-net in its various forms. This net is mostly
circular, and is loaded round the edge with small leaden plummets. It is
evident that, if such a net could be laid quite flat upon the water, it
would assume a dome-like shape, in consequence of the circumference
being heavier than the centre, and would sink to the bottom, enclosing
anything which came within its scope.
The difficulty is to place the net in such a manner, and this is
accomplished by throwing it in a very peculiar way. The net is gathered
in folds upon the shoulder, which it partially envelops. By a sudden
jerk the thrower causes it to fly open with a sort of spinning movement,
and when well cast it will fall on the water perfectly flat.
After allowing it to sink to the bottom, the fisherman draws it very
gently by a cord attached to its middle. As he raises it the weights of
the leaded circumference are drawn nearer and nearer together by their
own weight, and finally form it into a bag, within which are all the
living creatures which it has enclosed.
Though the Casting-net has never been used in warfare, it was one of the
favourite implements in gladiatorial combats among the Romans. Two men
were opposed to each other; one, called the Retiarius or Netsman, being
quite naked, except sometimes a slight covering round the waist, and
armed with nothing but a Casting-net and a slight trident, which could
not inflict a deadly wound. The other, called the Secutor or Follower,
from his mode of fighting, was armed with a visored helmet, a broad
metal belt, and armour for the legs and arms. He also carried a shield
large enough to protect the upper part of the body, and a sword. It will
be seen, therefore, how great was the power of the Casting-net, when it
enabled its naked bearer to face such odds of offensive and defensive
armour.
[Illustration: ARGUS STAR FISH. “FAN” OF BARNACLE. RETIARIUS.]
When the two met in combat, the Retiarius tried to fling his net over
his adversary, and if he succeeded, the fate of the latter was sealed.
Entangled in the loose meshes, he could scarcely move his limbs, while
the sharp prongs of the long-shafted trident came darting in at every
exposed point, and exhausting the man with pain and loss of blood. The
trident was in itself so feeble a weapon, that if the Secutor were
vanquished and condemned to death by the spectators, his antagonist
could not kill him, but had to call another Secutor to act as
executioner with his sword.
Should he fail in his cast, the Retiarius drew back his net by the
central cord, and took to flight, followed by the Secutor, who tried to
wound him before he could re-fold his net upon his shoulder, ready for
another cast. It is worthy of notice that in these singular combats the
netsman seems generally to have been the victor. A Retiarius with his
net is shown in the illustration.
I may mention that our ordinary bird-catchers’ nets, and even the
entomologist’s insect-net, are only modifications of the Casting-net.
* * * * *
NOW for Nature’s Casting-nets, two examples of which are figured, though
there are many more. These two have been selected because they are
familiar to all naturalists.
The first is the Argus Star-fish, Basket-urchin, or Sea-basket. The
innumerable rays and their subdivisions, amounting to some eighty
thousand in number, act as the meshes of the net. All the rays are
flexible and under control. When the creature wishes to catch any animal
for prey, it throws its tentacles over it, just like the meshes of a
net. It then draws the tips of the rays together, just as is done by the
circumference of the casting-net, and so encloses its prey effectually.
* * * * *
THE next specimen is the net-like apparatus of the common Acorn
Barnacles, with which our marine rocks are nearly covered. These curious
beings belong to the Crustacea, and the apparatus which is figured on
page 89, and popularly called the “fan,” is, in fact, a combination of
the legs and their appendages of bristles, &c. When the creature is
living and covered with water, the fan is thrust out of the top of the
shell, expanded as far as possible, swept through the water, closed, and
then drawn back again. With these natural casting-nets the Barnacles
feed themselves, for, being fixed to the rock, they could not in any
other way supply themselves with food. There are many similar examples
in Nature, but these will suffice.
THE ROD AND LINE.
That both terrestrial and aquatic nets should have their parallels in
Nature is clear enough to all who have ever seen a spider’s web, or
watched the “fan” of the barnacle. But that the rod and baited line, as
well as the net, should have existed in Nature long before man came on
earth, is not so well known. Yet, as we shall presently see, not only is
the bait represented in Nature, but even our inventions for “playing” a
powerful fish are actually surpassed.
We will begin with the Bait.
In nearly all traps a bait of some kind is required, in order to attract
the prey, and when we come from land to attract the dwellers in water to
our hooks, it is needful that bait of some kind should be used, were it
only to deceive the eye, though not the nostrils or palate, of the fish.
A notable example of the deception is given in the common artificial
baits of the present day, which are made to imitate almost any British
insect which a fish might be disposed to eat.
Perhaps the best instance of this deception is that which is practised
by sundry Polynesian tribes. They have seen that the Coryphene or
Dorado, and other similar fish, are in the habit of preying upon the
flying-fish, and springing at them when they are tolerably high in the
air. So these ingenious semi-savages dress up a hook made of bone,
ormer-shell, and other materials, making the body of it into a rudely
designed form of a fish. A hole is bored transversely through it at the
shoulders, and a bunch of stiff fibres is inserted to represent the
wings. Another bunch does duty for the tail.
The imitation bait being thus complete, it is hung to a long and slender
bamboo rod, which projects well beyond the stern of a canoe, and is so
arranged that the hook is about two feet or so from the surface. The
Coryphene, seeing this object skimming along, takes it for a
flying-fish, leaps at it, and is caught by the hook. There are in
several collections specimens of these ingenious hooks, and I possess
one which is made on similar principles, but intended for use in the
water, and not in the air. It is, in fact, a “spoon-bait.”
One point of ingenuity must be mentioned, as it really belongs to the
principle of the bait. These same savages, having noticed that large
sea-birds are in the habit of hovering over the flying-fish, and would
probably be seen by the Coryphenes, rig up a very long bamboo rod, tie
to its end a large bundle of leaves and fibres, and then fix it in the
stern of the boat, the sham bird being hung some twenty feet above the
sham fish. There is a refinement of deception here, for which we should
scarcely give such savages their due credit.
* * * * *
IN Art, then, we bait our hooks either with real or false food, and so
attract the fish.
In Nature we have a most accomplished master of the art of baiting, who
has the wonderful power of never needing a renewal of his bait. A glance
at the left-hand figure of the next illustration will show that I allude
to the Angler-fish, sometimes called the Fishing-frog (_Lophius
piscatorius_). This remarkable creature has a most enormous mouth, and
comparatively small body. On the top of its head are some curious bones,
set just like a ring and staple, so as to move freely in every
direction. A figure of this piece of mechanism will be given in a
future page. At the end of these bones are little fleshy appendages,
which must be very tempting to most fish, which are always looking out
for something to eat. As they are being waved about, they look as if
they were alive. The fish darts at the supposed morsel, and is at once
engulfed in the huge jaws of the Angler-fish, which, but for this
remarkable apparatus, would be scarcely able to support existence, as it
is but a sluggish swimmer, and yet needs a large supply of food. The
illustration, representing on the right hand a fish attracted to a bait,
and on the left, the Angler-fish, with its bait-like appendage to the
head, speaks for itself.
[Illustration: ANGLER-FISH. ANGLING.]
* * * * *
PASSING to the art of Angling with a rod and line, we now arrive at
another development.
Supposing a fish to have taken the bait, and to have been firmly hooked,
how is it to be landed? The simplest plan is, of course, to have a very
thick and strong line which will not break with the weight of any
ordinary fish.
This is very well in sea-fishing, where a line made of whip-cord will
answer the purpose in most cases. But, in river fishing, we have the
fact that the fish are so shy that a linen thread would scare them, and
so strong and active, that even whip-cord would not prevent them from
breaking the line, or tearing the hook out of their mouths. So the
modern angler sets himself to the task of combating both these
conditions. In the first place, he makes the last yard or two of his
line of “silkworm-gut”--a curious substance made from the silk-vessels
of silkworms, and nearly invisible in the water. In the next place, he
has a very elastic rod; and, in the third, he has forty or more yards of
line, though perhaps only twenty feet are in actual use until the fish
is hooked. The remainder of the line is wound upon a winch fixed to the
handle of the rod. Thus, when a powerful fish is hooked and tries to
escape, the line is gradually let loose, so as to yield to its efforts.
When it becomes tired by the gradual strain, the line is again wound in,
and in this way a fish which would at the first effort smash rod and
line of a novice will, in the hands of an experienced fisherman, be
landed as surely as if it were no bigger than a gudgeon.
* * * * *
NATURE has in this case also anticipated Art, and surpassed all her
powers.
[Illustration: NEMERTES. “PLAYING” A FISH.]
There is a wonderful worm, common on our southern coasts, and bearing,
as far as I know, no popular name. It is known to the scientific world
as _Nemertes Borlasii_. It possesses the power of extension and
contraction more than any known creature, and uses those powers for the
purpose of capturing prey. The fishermen say that this worm can extend
itself to a length of ninety feet, and as Mr. Davis found one to measure
twenty-two feet, after being immersed in spirits of wine, it is likely
that their account may be true, especially as the spirit greatly
contracted the animal in point of length.
A most vivid description of this worm is given by C. Kingsley, in his
“Glaucus,” and was written before he knew its name.
“Whether we were intruding or not, in turning this stone, we must pay a
fine for having done so; for there lies an animal as foul and monstrous
to the eye as ‘hydra, gorgon, or chimæra dire,’ and yet so wondrously
fitted to its work that we must needs endure for our own instruction to
handle and to look at it. Its name I know not (though it lurks here
under every stone), and should be glad to know. It seems some very ‘low’
Ascarid or Planarian worm.
“You see it? That black, shiny, knotted lump among the gravel, small
enough to be taken up in a dessert spoon. Look now, as it is raised and
its coils drawn out. Three feet, six, nine at least; with a capability
of seemingly endless expansion; a slimy tape of living caoutchouc, some
eighth of an inch in diameter, a dark chocolate black, with paler
longitudinal lines.
“Is it alive? It hangs helpless and motionless, a mere velvet string,
across the hand. Ask the neighbouring Annelids and the fry of the
rock-fishes, or put it into a vase at home, and see. It lies motionless,
trailing itself among the gravel; you cannot tell where it begins or
ends; it may be a dead strip of seaweed, _Himanthalia lorea_, perhaps,
or _Chorda filum_, or even a tarred string.
“So thinks the little fish who plays over and over it, till he touches
at last what is too surely a head. In an instant a bell-shaped sucker
mouth has fastened to his side. In another instant, from one lip, a
concave double proboscis, just like a tapir’s (another instance of the
repetition of forms), has clasped him like a finger; and now begins the
struggle: but in vain. He is being ‘played’ with such a fishing-line as
the skill of a Wilson or a Stoddart never could invent; a living line,
with elasticity beyond that of the most delicate fly-rod, which follows
every lunge, shortening and lengthening, slipping and twining round
every piece of gravel and stem of seaweed, with a tiring drag such as no
Highland wrist or step could ever bring to bear on salmon or on trout.
“The victim is tired now; and slowly, and yet dexterously, his blind
assailant is feeling and shifting along his side, till he reaches one
end of him; and then the black lips expand, and slowly and surely the
curved finger begins packing him end foremost down into the gullet,
where he sinks, inch by inch, till the swelling which marks his place is
lost among the coils, and he is probably macerated to a pulp long before
he has reached the opposite extremity of his cave of doom.
“Once safe down, the black murderer slowly contracts again into a
knotted heap, and lies, like a boa with a stag inside him, motionless
and blest.”
The accuracy as well as the pictorial effect of this description cannot
be surpassed. The “velvety” feel of the creature is most wonderful, as
it slips and slides over and among the fingers, and makes the task of
gathering it together appear quite hopeless.
This astonishing worm is drawn on the left hand of the illustration on
page 93, so as to show the way in which the body is contracted or
relaxed at will. On the other side of the illustration is an angler,
armed with all the paraphernalia of his craft, and doing imperfectly
that which the Nemertes does with absolute perfection.
A similar property belongs to the long, trailing tentacles of the
Cydippe, which is described and figured on page 16. When they come in
contact with suitable prey, all struggle is useless, the tentacles
contracting or elongating to suit the circumstances, and at last lodging
the prey within the body of the Cydippe.
THE SPRING-TRAP.
We are all familiar with the common Spring-trap, or Gin, as it is
sometimes called.
It varies much in form and size, sometimes being square and sometimes
round; sometimes small enough to be used as a rat-trap, and sometimes
large enough to catch and hold human beings, in which case it was known
by the name of man-trap. This latter form is now as illegal as the
spring-gun, and though the advertisement “Man-traps and Spring-guns are
set in these grounds” is still to be seen, neither one nor the other can
be there.
They are all constructed on the same principle, namely, a couple of
toothed jaws which are driven together by a spring, when the spring is
not controlled by a catch. They are evidently borrowed from actual jaws,
the same words being used to signify the movable portions and notches of
the trap as are employed to designate the corresponding parts in the
real jaw.
In both figures of the accompanying illustration we shall see how exact
is the parallel. On the right hand is a common rat-trap, or gin, such as
is sold for eightpence, with the jaws wide open, so as to show the
teeth. On the left is a sketch of the upper and lower jaws of the
Dolphin, in which an exactly analogous structure is to be seen.
[Illustration: JAWS OF DOLPHIN (OPEN). RAT-TRAP (OPEN).]
The figure on the right hand of the lower illustration shows a man-trap
as it appears when closed, the teeth interlocking so as exactly to fit
between each other. The same principle is exhibited in the jaws of the
Porpoise, which are seen on the left of the illustration. The jaws of an
Alligator or Crocodile would have answered the purpose quite as well,
inasmuch as their teeth interlock in a similar fashion, but I thought
that it would be better to give as examples the jaws of allied animals.
The reason for this interlocking is evident. All these creatures feed
principally on fish, and this mode of constructing the jaws enables them
to secure their prey when once seized.
[Illustration: JAWS OF PORPOISE (CLOSED). MAN-TRAP (CLOSED).]
[Illustration: FORE-LEGS OF PHASMA. MOUSE-TRAP.]
Another example of such teeth is to be found in the fore-legs of various
species of Phasma and Mantis, as may be seen by reference to the
illustration. The latter insects are wonderfully fierce and pugnacious,
fighting with each other on the least provocation, and feeding mostly on
other insects, which they secure in their deeply-toothed fore-legs.
They use these legs with wonderful force and rapidity, and it is said
that a pair of these insects fighting remind the observer of a duel with
sabres.
THE BAITED TRAP.
Our space being valuable, we are not able to give many examples of
Baited Traps, whether in Art or Nature.
The most familiar example of this trap is the common Mouse-trap, the
most ordinary form of which is shown at the right hand of the
illustration on page 96. In all the varieties of these traps, whether
for mice or rats, the prey is induced to enter by means of some tempting
food, and then is secured or killed by the action of the trap. Sometimes
these traps are made of considerable size for catching large game, and
in Africa are employed in the capture of the leopard, in India for
taking both tigers and leopards, and in North America for killing bears.
We have already noticed one instance of a bait in the Angler-fish,
described in page 92, but in this case the bait serves only for
attraction, and the trap, or mouth, is not acted upon by the prey.
There are, however, many examples in the botanical world, where the
plant is directly acted upon by the creature which is to be entrapped,
such being known by the now familiar term “Carnivorous Plants.” Of these
there is a great variety, but under this head I only figure two of them.
[Illustration: CEPHALOTUS. DIONEA.]
The plant on the right hand is the Venus Fly-trap (_Dionea muscipula_),
which is common in the Carolinas. The leaves of this plant are
singularly irritable, and when a fly or other insect alights on the
open leaf, it seems to touch a sort of spring, and the two sides of the
leaf suddenly collapse and hold the insect in their grasp. The strange
point about it is, that not only is the insect caught, but is held until
it is quite digested, the process being almost exactly the same as if it
had been placed in the stomach of some insect-eating animal.
So carnivorous, indeed, is the Dionea, that plants have been fed with
chopped meat laid on the leaves, and have thriven wonderfully.
Experiments have been tried with other substances, but the Dionea would
have nothing to do with them. The natural irritability of the leaves
caused them to contract, but they soon opened and rejected the spurious
food.
On the left is the Cephalotus. This plant, instead of catching the
insect by the folding of the leaf, secures it by means of a sort of
trap-door at the upper end. The insect is attracted by the moisture in
the cup, and, as soon as it enters, the trap-door shuts upon it, and
confines it until it is digested, when the door opens in readiness to
admit more prey.
BIRDLIME.
By a natural transition we pass to those traps which secure their prey
by means of adhesive substances.
With us, the material called “birdlime” is usually employed. This is
obtained from the bark of the holly, and is of the most singular
tenacity. An inexperienced person who touches birdlime is sure to repent
it. The horrid stuff clings to the fingers, and the more attempts are
made to clear them, the more points of attachment are formed. The novice
ought to have dipped his hands in water before he touched the birdlime,
and then he might have manipulated it with impunity.
The most familiar mode of using the birdlime is by “pegging” for
chaffinches.
In the spring, when the male birds are all in anxious rivalry to find
mates, or, having found them, to defend them, the “peggers” go into the
fields armed with a pot of birdlime and a stuffed chaffinch set on a peg
of wood. At one end of this peg is a sharp iron spike. They also have a
“call-bird,” _i.e._ a chaffinch which has been trained to sing at a
given signal.
When the “peggers” hear a chaffinch which is worth taking, they feel as
sure of him as if he were in their cage. They take the peg, and stick it
into the nearest tree-trunk. Round the decoy they place half-a-dozen
twigs which have been smeared with birdlime, and arrange them so that no
bird flying at the decoy can avoid touching one of them.
[Illustration:
ANT-BEAR. DROSERA. SPIDER’S WEB.
PEGGING CHAFFINCHES. TIGER AND LIMED LEAVES.]
The next point is, to order the call-bird to sing. His song is taken as
a personal insult by the chaffinch, which is always madly jealous at
this time of year. Seeing the stuffed bird, he takes it for a rival,
dashes at it, and touches one of the twigs. It is all over with him, for
the more he struggles and flutters, the tighter is he bound by the
tenacious cords of the birdlime, and is easily picked up by the
“pegger.”
* * * * *
EVEN the fierce and powerful tiger is taken with this simple, but
terrible means of destruction. It is always known by what path a tiger
will pass, and upon this path the native hunter lays a number of leaves
smeared with birdlime. The tiger treads on one of them, and, cat-like,
shakes his paw to rid himself of it. Finding that it will not come off,
he rubs his paw on his head, transferring the leaf and lime to his face.
By this time he is in the middle of the leaves, and works himself into a
paroxysm of rage and terror, finishing by blinding himself with the
leaves that he has rubbed upon his head. The hunters allow him to
exhaust his strength by his struggles, and then kill him, or, if
possible, capture him alive.
Both these scenes are represented on the right hand of the illustration.
On the left hand are several examples of natural birdlime, if we may use
the term. The upper represents the Ant-bear, or Great Ant-eater. This
animal feeds in a very curious manner. It goes to an ant-hill, and tears
it open with its powerful claws. The ants, of course, rush about in wild
confusion. Now, the Ant-eater is provided with a long, cylindrical
tongue, which looks very like a huge earth-worm, and which is covered
with a tenacious slimy secretion. As the ants run to and fro, they
adhere to the tongue, and are swept into the mouth of their destroyer.
Below the Ant-eater is the common Drosera, or Sundew, one of our British
carnivorous plants. It captures insects, just as has been narrated of
the Dionea. But, instead of the leaf closing upon the insect, it arrests
its prey by means of little globules of viscous fluid, which exude from
the tips of the hairs with which the surface of the leaf is covered. As
soon as the insect touches the hairs, they close over it, bind it down,
and keep it there until it is digested. Several species of Drosera are
known in England, and are found in wet and marshy places.
Another plant, the Green-winged Meadow Orchis (_Orchis morio_), has been
known to act the part of the Drosera. A fly had contrived to push its
head against the viscous fluid of the stigmatic surface, and, not being
able to extricate itself, was found sticking there.
Next comes a portion of the web of the common Garden Spider (_Epeira
diadema_). We have already treated of this web as a net, and we will now
see how it comes within the present category.
In the web of the spider there are at least two distinct kinds of
threads. Those which radiate from the centre to the circumference are
strong and smooth, while those which unite them are much slighter, and
are covered with tiny globules set at regular intervals. When the web is
newly spun, these globules are found to be nearly as tenacious as
birdlime, and it is by these means that an insect which falls into the
web is arrested, and cannot extricate itself until the spider can seize
it. After awhile the globules become dry, refuse to perform their
office, and then the spider has to construct another web. So numerous
are these globules that, according to Mr. Blackwall’s calculations, an
ordinary net contains between eighty and ninety thousand. Below the
figure of the web itself are shown the two kinds of thread, the upper
bearing the globules, and the lower representing one of the plain
radiating threads.
WAR AND HUNTING.
CHAPTER V.
Reverted Spikes and their Modifications.--The Wire
Mouse-trap.--George III. and the Trap.--Fate of a Royal
Finger.--The Crab and Lobster Pot.--The Eel-pot.--Cocoon of the
Emperor-moth and its Structure.--“Catchpoll” of the Middle
Ages.--Deer-trap of India.--Jaws of Pike and Serpent.--The
Grass-snake.--Jaws of Shark and their Power.--Spiked Defences.--The
Park Fence, the Garden Wall, and the Chevaux-de-frise.--The
“Square” of Infantry Manœuvres.--The Abattis, and its Structure
and Power.--Ranjows and Caltrops.--Ancient Ranjows in
Ireland.--Hedgehog.--Porcupine Echidna.--House-builder Caterpillar
and its Home.--Repagula of Ascalaphus.--Tearing Weapons.--The
“Wag-nuk” of India.--Armed Gauntlet of the Middle
Ages.--Shark-tooth Gauntlet of Samoa, and the Uses to which it was
put.--A terrible Warrior.--The Tiger’s Claw.--Sport and Earnest.
REVERTED SPIKES.
I am not quite satisfied with this title, but it is the best that I can
find. By it I mean that mode of mechanism which, by means of an array of
sharp spikes, permits an animal to enter a passage easily, and yet
prevents it from emerging.
[Illustration: COCOON OF EMPEROR-MOTH. CRAB-POT. EEL-POT. MOUSE-TRAP.]
Whether or not this principle be now employed in warfare I cannot say,
but it is at all events used extensively in a small way of hunting, the
best known of which is the wire Mouse-trap, one of which is shown at
Fig. C on the illustration. A glance at the figure will explain the
trap, even to those who have never seen it. It is composed entirely of
wire, and has several round holes just above its lower edge. Each of
these holes is the entrance to a conical tunnel made of wires with
sharpened ends.
The mouse, being attracted by a bait placed within the trap, tries to
get at it. The doomed animal soon finds its way to one of the entrances,
and with little difficulty pushes itself through the tunnel. Entering,
however, is one thing, and returning is another. The wire yielded easily
enough in one direction, but for the mouse to force itself against the
converging points is an impossible task.
Readers of the last century literature may perhaps remember, in the
pages of “Peter Pindar,” a very clever and sarcastic account of the
astonishment created in the mind of George III. by a mouse-trap seen
accidentally in the house of a widow living at Salt Hill.
“Eager did Solomon, so curious, clap
His rare round optics on the widow’s trap,
That did the duty of a cat.
And, always fond of useful information,
Thus wisely spoke he with vociferation,--
‘What’s that? what? what? Hæ, hæ? what’s that?’
To whom replied the mistress of the house,
‘A trap, an’t please you, sir, to catch a mouse.’
‘Mouse--catch a mouse!’ said Solomon with glee;
‘Let’s see, let’s see--’tis comical--let’s see--
Mouse! mouse!’--then pleased his eyes began to roll--
‘Where, where doth he go in?’ he marvelling cried.
‘There,’ pointing to the hole, the dame replied.
‘What! here?’ cried Solomon, ‘this hole? this hole?’
Then in he pushed his finger ’midst the wire,
That with such pains that finger did inspire,
He wished it out again with all his soul.”
For my part I think that the King was quite right. If he did not know
the philosophy of a mouse-trap he ought to have asked, and to have been
rewarded, as in that case, by catching with a trap of his own baiting,
six mice on six successive days.
At Fig. B on the same illustration is shown the simple apparatus by
which crabs and lobsters are caught. The reader will see that the
principle is exactly the same in both cases, the only difference being
in material, the mouse-trap being made of wire, and the crab-pot of
wicker.
At Fig. D is shown the common Eel-pot, or Eel-basket. In order to suit
the peculiar shape of an eel, this basket is much longer in proportion
to its diameter than either of the preceding traps, but it is formed on
the same plan. An eel can easily pass into the basket through the
conical tunnel, but it is next to impossible that it should find its way
out again.
* * * * *
SO much for Art, and now for Nature.
On the left hand of the illustration, at Fig. A, is the cocoon of the
common Emperor-moth (_Saturnia pavonia minor_), the cocoon having been
stripped of its outer envelope, so as to allow its structure to be
better seen.
The reader will at once perceive that the entrance of the cocoon is
guarded by an arrangement exactly like that of the above-mentioned
traps, except that the cone is reversed, so as to allow of exit and to
debar entrance. Guarded by this conical arrangement of stout bristly
appendages, the pupa can remain in quiet during the time of its
transformation, for nothing can force its way through such a defence,
and yet the moth, when fully developed, can push its way out with
perfect ease.
So admirably is this cocoon formed, that even after the moth has
escaped, it is impossible to tell by mere sight whether or not it is
within, the elastic wires closing on it after its passage.
* * * * *
ANOTHER modification of the same principle now comes before us. In the
above-mentioned examples the arrangement of the reverted spikes is more
or less conical, and they lead into a chamber. In the present instances,
however, the mere reversion of the points is all that is needed.
The upper figure on the right hand represents the “Catchpoll” of the
Middle Ages, an allusion to which has already been made. The reverted
spikes turn on hinges, and are kept apart by springs. This beautifully
formed head was attached to a long shaft, and was used for the purpose
of dragging horsemen from the saddle. It was thrust at the neck of the
rider, generally from behind. If a successful thrust were made, the
spring-points gave way, sprang back again, and thus clasped the neck
with a hold that was fatal to the rider.
* * * * *
BELOW it is the Deer-trap which is used in many parts of India, and to
which allusion has already been made. The reader will see at once that
if a deer should get its foot through the converging spikes, its doom
is sealed, especially as there is a heavy log of wood attached to the
trap by a rope.
* * * * *
ON the left hand of the illustration are two examples of the same
principle taken from Nature, one belonging to fresh and the other to
salt water.
[Illustration: PIKE-JAWS. SHARK-JAWS. CATCHPOLL. DEER-TRAP.]
The upper figure represents the jaws of a Pike, with their terrible
array of reverted teeth. The Pike, as every one knows, feeds upon other
fish, and eats them in a curious manner. It darts at them furiously, and
generally catches them in the middle of the body. After holding them for
a time, for the purpose, as I imagine, of disabling them, it loosens its
hold, makes another snap, seizes the fish by the head, and swallows it.
The Pike is so voracious that it will attack and eat fish not very much
smaller than itself, for its digestion is so rapid that the head and
shoulders of a swallowed fish have been found to be half digested, while
the tail was sticking out of the Pike’s mouth. Unless, therefore, the
teeth of the Pike were so formed as to resist any retrograde movement on
the part of the prey, the fish would starve; for, lank and lean as it
is, the Pike is one of the most voracious creatures in existence, never
seeming able to get enough to eat, and yet, as is often found in such
cases, capable of sustaining a lengthened fast.
How well adapted is this arrangement of teeth for preventing the escape
of prey, any one can tell who, in his early days of angling, caught a
Pike, and, after killing it, tried to extract the hook without
previously propping the jaws open. If once the hand be inserted between
the jaws, to get it out again is almost impossible without assistance,
and often has the spectacle been exhibited of a youthful angler
returning disconsolately home, with his right hand in the mouth of a
Pike, and supporting the weight of the fish with his left.
* * * * *
THE teeth of a serpent are set in a similar manner, as can be seen by
reference to the illustration on page 80. An admirable example of the
power of this arrangement may be seen in the jaws of our common Grass or
Ringed Snake (_Coluber natrix_). The teeth are quite small, very short,
and not thicker than fine needle-points. Yet, when once the snake has
seized one of the hind-feet of a frog, all efforts to escape on the part
of the latter are useless. The lower jaw is pushed forward, and then
retracted, and at each movement the leg is drawn further into the
snake’s mouth, until it reaches the junction.
The snake then waits quietly until the frog tries to free itself by
pushing with its other foot against the snake’s mouth. That foot is then
seized, the leg gradually following its companion, and in this way the
whole frog is drawn into the interior of the snake. I have seen many
frogs thus eaten, but never knew one to escape after it had been once
seized by the snake. As these reptiles are perfectly harmless, it is
easy to try the experiment by putting the finger into a snake’s mouth,
when it will be found that the assistance of the other hand will be
needful in order to extricate it.
* * * * *
BELOW the head of the pike is a view of a Shark’s jaws, as seen from the
front.
Here, again, we have a similar arrangement of teeth, row after row of
which lie with their points directed towards the throat of the fish. As,
however, the pike and the snake swallow their prey whole, their teeth
need be nothing but points. But, as the Shark is obliged to mangle its
prey, and seldom swallows it whole, its teeth are formed on a different
principle, each tooth being flat, wide, sharply pointed, and having a
double edge, each of which cuts like a razor. So knife-like are they,
indeed, that when a whale is killed, the sharks which surround it bite
off huge mouthfuls of blubber, and, as they swarm by hundreds, cause no
small loss to the whalers.
Many a man has lost a leg by a shark, the fish having bitten it
completely through, bone and all, and there have been cases where a
shark has actually severed a man’s body, going off with one half, and
leaving the other clinging to the rope by which he was trying to haul
himself on board.
SPIKED DEFENCES.
This mode of defence is, perhaps, one of the most primitive in
existence, and takes a wonderful variety of forms. The spiked railings
of our parks and gardens, the broken glass on walls, and even the spiked
collars for dogs, are all modifications of this principle.
On the illustrations are several examples of spikes used for military
purposes. The first is known by the name of “Chevaux-de-frise,” and is
extensively used in forming an extemporised fence where no great
strength is needed. The structure is perfectly simple, consisting of a
number of iron bars with sharpened ends, and an iron tube some inches in
diameter, which is pierced with a double set of holes. When not in use,
the bars and tube can be packed in a small compass, but when they are
wanted, the bars are thrust through the holes as shown in the
illustration, and the fence is completed in a few minutes. The
horizontal bars are linked together by chains, so as to prevent them
from being shifted, and a defence such as this is generally used for
surrounding parks of artillery and the like.
* * * * *
ALL who have the least acquaintance with military matters must be
familiar with the “Square,” and its uses in the days of old. I say in
the days of old, because in the present day the rapid development of
guns and rifles has entirely destroyed the old arrangement. So lately,
for example, as the day of Waterloo, troops might manœuvre in safety
when they were more than two hundred yards from the enemy. Now, a
regiment that attempted to manœuvre in open ground would be cut to
pieces by the rifles of the enemy at a thousand yards’ distance.
In those days, however, the square was a tower of safety when rightly
formed. It was formed in several rows. The outer line knelt, with the
butts of their muskets on the ground, and the bayonet pointing upwards
at an angle of forty-five. The others directed their muskets towards
the enemy in such a manner that nothing was presented to him but the
points of bayonets and the muzzles of loaded muskets. In all probability
the battle of Waterloo would have been lost but for the use of the
“square,” against which the French cuirassiers dashed themselves
repeatedly, but in vain.
However admirable may be the organization of the square, whether it be
hollow, or whether it be solid, like the “rallying square,” the
principle is the same as that of the chevaux-de-frise.
* * * * *
IN the next illustration is shown the “Abattis,” one of the most
important elements of extemporised fortifications, and as simple as it
is important.
[Illustration: TREE-CADDIS.]
[Illustration: CHEVAUX-DE-FRISE.]
In any wooded country an abattis can be made in a very short time by
practised hands. All that is required is to cut down the requisite
number of trees, strip off the leaves and twigs, and then cut off the
smaller branches with sloping blows of the axe, so as to leave a
tolerably sharp point on each. The trees are then laid side by side,
with the ends of the branches towards the enemy, and, the trunks being
chained together, a wonderfully effective defence is constructed.
Not only is it almost impossible for the bravest and strongest man to
force his way through the branches, even if the abattis were undefended,
but the tree-trunks afford shelter for swarms of riflemen, who can pick
off their assailants by aiming between the branches, themselves being
almost unseen, and entirely covered.
[Illustration: CALTROPS.]
[Illustration: RANJOWS.]
[Illustration: ABATTIS.]
In Southern Africa, during the late wars, the abattis was found to
afford the best defence against the Kafirs, and that when the waggons
and abattis were united so as to form a fortress, not even the naked
Kafir, with all his daring courage, could force his way through them.
Even artillery has but little power against the abattis, which allows
the shot to pass between the branches, and is very little the worse for
it. Accordingly, it is in great use for defending roads, especially
those which are bounded by high banks, and makes a formidable obstacle
in front of gates.
* * * * *
THE two figures on the left of the same illustration represent two modes
of carrying out the same principle, the one showing it as used in
European warfare, and the other as a weapon of defence which has been
employed from time immemorial, and is now in full use in many parts of
the world.
Both these weapons are intended either to obstruct the approach of an
enemy, or to cover the flight of a retreating force. The most simple and
most ancient is the Ranjow, which is shown on the right hand of the
illustration. The ranjow is nothing but a wooden stick varying in length
from eighteen inches to nearly three feet, and sharply pointed at each
end. In Borneo, China, &c., the ranjows are almost invariably made of
bamboo, as that plant can be cut to a sharp point by a single stroke of
a knife. (See page 59.)
When they are to be used, each soldier carries about a dozen or so of
them, and sticks one end of them into the ground, taking care to make
the upper end lean towards the enemy. Simple as are these weapons, they
are extremely formidable, for it is necessary to pull up every ranjow
before the troops can advance. Sometimes it has happened that a body of
soldiers are driven over their own ranjows, and then the slaughter is
terrible.
Some years ago a number of sketches were taken on the spot from scenes
in the Chinese war. Among them was one that was absolutely terrible in
its grotesqueness. It represented a piece of ground thickly planted with
ranjows, over which the Chinese who had fixed them had been driven. They
were simply hung with human bodies in all imaginable and unimaginable
attitudes, some transfixed on a single ranjow, and others hanging on
three or four, the body and limbs being alike pierced by them.
That ranjows were once used in Great Britain is evident from a discovery
made by Col. Lane Fox. He had been excavating the soil around an old
Irish fort, and deep beneath the bog he found a vast quantity of ranjows
still set as the ancient warriors had left them. They were evidently
used to defend a passage leading to the fort, and all of them were
carefully set with their points outwards. Col. L. Fox was good enough to
present me with several of these ancient weapons, which are now in my
collection.
* * * * *
ON the left is seen a piece of ground strewed with Caltrops, or
Crow’s-feet, as they are sometimes called. These very unpleasant
implements are made of iron, and have four sharp points, all radiating
from one centre, so that no matter how they may be thrown, one point
must be uppermost. They are used chiefly for the purpose of impeding
cavalry, but I should think, judging from the specimens which I have
seen, that infantry would find them very awkward impediments.
* * * * *
AS for natural ranjows, they are so numerous that only a very few
examples can be given.
The most perfect and most familiar example is, perhaps, the common
Hedgehog, which, when rolled up, displays an array of sharp points so
judiciously disposed, that it fears but very few foes. The same may be
said of the Australian Echidna, or Porcupine Ant-eater, and the
Porcupine itself. Whether the radiating bristles of the larva of the
Tiger-moth, commonly called the Woolly Bear, come under the same
category, I cannot say, but think it very likely.
Among vegetables the analogues are multitudinous. See, for example, the
spikes of the Spanish and Horse Chestnuts, and especially the hair-like
but formidable bristles which defend the common Prickly Pear. Indeed,
all that tribe of plants is furnished so abundantly with natural
ranjows, that a hedge of prickly pear forms the best defence which a
house and garden can have.
Another example of natural ranjows is seen in the Tree-caddis, one of
which is shown in the illustration on page 108, as it appears when
suspended from a twig. It is the work of one of the House-builder Moths
of the West Indies, and forms a sort of house in which the caterpillar
can rest securely. It is built of bits of twigs and thorns, the latter
being disposed so that their points are outwards, much after the fashion
of a hedgehog’s spines.
I possess many specimens of Tree-caddis, evidently belonging to several
species, and in all of them the principle is the same, _i.e._ a number
of spikes set with their ends outwards in order to defend a central
position.
Sometimes these spikes are left exposed, as shown in the illustration,
and sometimes they are covered with a slight but strong web. The
principle, however, is the same in all.
* * * * *
NOW I shall have to use two very long words, and much against my will. I
very much fear that, if most of my readers were to hear any one speak of
the “repagula of Ascalaphus,” they would not be much the wiser. And yet
there are no other words that can be used.
In the first place, Ascalaphus is a name belonging to a genus of
Ant-lions, remarkable for having straight, knobbed antennæ, very much
like those of a butterfly. This insect deposits its eggs in a double row
on twigs, and then defends them with a series of natural ranjows, set in
circular rows, and supposed to be without analogies in the animal
creation. They are transparent, reddish, and “are expelled by the female
with as much care as though they were real eggs, and are so placed that
nothing can approach the brood; nor can the young ramble abroad until
they have acquired strength to resist the ants and other insect
enemies.”
The word “repagulum,” by the way, signifies a bar or barrier. A
turnpike gate when closed would be a repagulum, and so would a
chevaux-de-frise.
TEARING WEAPONS.
We have already had examples of weapons, like the Club, which bruise; of
weapons, like the Spear and Dagger, which pierce; and of weapons, like
the Sword, which cut. We now come to a totally distinct set of weapons,
those which wound by tearing, and not by any of the preceding modes.
In civilised warfare we have long abandoned such weapons, as belonging
to a barbarous age, but they are even yet employed in some parts of the
world.
[Illustration:
WAG-NUK OF INDIA.
HIND-CLAWS OF TIGER.
CLAWED GAUNTLET.
SHARK-TOOTH GAUNTLET.]
The accompanying illustration shows three examples of such weapons. One
is the celebrated Tiger-claw of India, known by the native name of
Wag-nuk. It is about two inches and a half in length, and is made to fit
on the hand. The first and fourth fingers are passed through the rings,
and the curved claws are then within the hand, and hidden by the
fingers. The mode of employing this treacherous weapon was by engaging a
foe in conversation, pretending to be very friendly, and then ripping up
his stomach with an upward blow of the right hand.
It is comparatively a modern weapon, having been invented about two
hundred years ago. A Hindoo, named Sewaja, was the inventor, and by
means of the Wag-nuk he committed many murders unsuspected, the wounds
being exactly like those which are made by the claw of the tiger.
Sometimes there were four claws instead of three, as is the case with a
specimen one in the Meyrick collection.
Perhaps the reader may be aware that the Transatlantic “knuckle-duster”
is fitted on the hand in the same manner, only its object is to strike a
heavy blow, and not to tear. History repeats itself, and the large and
clumsy “cestus” of the ancient athlete is reproduced in the small but
scarcely less formidable “knuckle-duster” of the modern rowdy.
The figures are remarkable, one representing the remaining epoch of
chivalry, and the other that of barbarism. The upper figure shows a
curious Gauntlet of the Middle Ages, in which the hand is not only
defended by steel plates, but is also rendered an offensive weapon by
the addition of four sharp spikes set just at the junction of the
fingers with the hand. As long as the fingers are extended the spikes
lie parallel with them, and are as harmless as a cat’s claws in their
sheaths. But when the fingers are closed, as shown in the illustration,
the spikes come into use, and can be made into a formidable weapon of
offence, just as are the cat’s claws when protruded.
* * * * *
BELOW the gauntlet of civilised warfare is one of savage war, which has
for many years been discontinued, partly on account of the introduction
of firearms, and partly owing to the superficial coating of civilisation
which is so easily adopted by the singular varieties of the human race
which populate the isles where this remarkable weapon was once worn. The
figure is taken from a specimen in the United Service Museum.
It is a Gauntlet, having at one end a band through which the whole hand
is passed, and at the other three loops for the fingers, just like those
of the Wag-nuk, which has already been described. The body of the weapon
is made of cocoa-nut fibre, and upon it are strung six rows of sharks’
teeth, the tips all pointing backwards. It is a Samoan weapon, some of
the most renowned warriors never using club nor spear, but trusting
entirely to their terrible gauntlets. With these they struck right and
left, dashing beneath the clubs and spears of their enemies, and always
trying to rip up their stomachs, just as is done with the Wag-nuk. In
order to guard against this weapon, the Samoan warrior wears a belt of
cocoa-nut fibre some eight inches wide, and thick enough to defy the
best gauntlet that could be made.
One celebrated Samoan warrior, a man of gigantic stature and strength,
was addicted to the amusement of seizing his enemies with the
shark-tooth gauntlets, breaking their backs across his knee, throwing
them down, and going off after another victim.
* * * * *
ON the left hand of the illustration is seen the hind-foot of the Tiger.
I have chosen the hind-foot for two reasons: firstly, because the
fore-foot has already been figured; and secondly, because the hind-foot
is used for tearing open the abdomen of the prey. Any one who has played
with a kitten has noticed how the animal throws itself on its back,
clasps the wrist with its fore-paws, and kicks vigorously with its
hind-legs. It does not mean to hurt its playfellow, but the hand does
not easily escape without sundry scratches.
Child’s play though it may be in the kitten, it is no play at all with
the tiger, or even the leopard, for either of these animals, when hard
pressed, will throw itself on its back, clasp the foe in its fore-paws,
and with the talons of the hind-feet tear him to pieces.
WAR AND HUNTING.
CHAPTER VI.
THE HOOK.--DEFENSIVE ARMOUR.--THE FORT.
Anglers and their Hooks.--Single and double Hooks.--Hook of British
Columbia.--Seed of Galium, or Goose-grass, and its Armature of
Hooks.--Seed of the Burdock, and its Annoyance to Sheep.--Hooked
Sponge-spicules.--“Snatching” Fish.--The Fish-rake of British
Columbia.--The “Gaff” and its Uses.--The Jaguar as a
Fisher--Defensive Armour and its Varieties.--Plate and Chain
Mail.--The Shield.--Australian and West African Shields.--Fibre
Armour.--Seal’s-tooth Cuirass.--Joints of
Armour.--“Tassets.”--Scale Armour in Art and Nature.--The Manis and
the Fish.--Feather Armour.--“Madoc in Aztlan.”--Quilted Armour of
Silk or Cotton.--Terrible Results from the latter.--Mr. Justice
Maulstatute.--Natural Quilt Armour.--The Rhinoceros and the
Whale.--The Testudo of the ancient Romans, and its Uses.--The
common Tortoise.--The Fort.--Curious Transitions in Fort building;
first Earth, then Stone, then Earth again.--Advantage of Earthen
Mounds.--Natural Snow-fort made by the Elk, and its Defensive
Powers against the Wolf.
THE HOOK.
Having now seen that the rod and line of anglers have their prototypes
in Nature, we will proceed to the hook, by which the fish are secured.
The two figures on the right hand of the accompanying illustration
represent hooks which are familiar to every angler. The lower is the
ordinary fish-hook, which can be used in so many ways. Generally it is
employed singly, being fastened to the end of a line, and armed with a
bait, either real or artificial. Sometimes, however, these hooks are
whipped together, back to back, three or even four being so employed,
and thus forming a combination of the hook and grapnel, and rendering
the escape of a fish almost impossible.
Above it is a double hook, such as is used in “trolling” for pike, and
with the use of which many of my readers are probably acquainted.
The third is a singularly ingenious hook made by the natives of British
Columbia. It is almost entirely made of wood, with the exception of the
barb, which is of bone. This, as the reader will see, is fixed, not to
the point of the hook, as with us, but to its base, the point being
directed towards the central portion of the curve.
[Illustration:
HYMEDESMIA. FRUIT OF GALIUM. VANCOUVER HOOK. DOUBLE AND
SINGLE HOOKS.]
At first sight this seems to be a singular arrangement, but it is a very
effective one, as any one may see by placing the point between the
fingers and pushing it through them. It will be found impossible to
force it back again, the sharp point of the bone-barb coming against
them and retaining them.
It has also another advantage. Very large fish, for which this hook is
intended, are apt in their struggles to reverse the hook, and so to
weaken its hold. In this hook, however, such a proceeding is impossible;
for, even should the hook be reversed, it still retains its hold, the
barb becoming the point, and the point keeping the lip of the fish
against the tip of the barb. The figure is drawn from a specimen in my
collection.
* * * * *
IF the reader will look at the illustration, he will see a globular
object covered with little hooks. This is a magnified representation of
the seed-vessel of the common Goose-grass (_Galium_), which is so
luxuriant in our hedges, and often intrudes itself into our gardens. Its
long, trailing stems, with their tightly-clinging leaves, are familiar
to all, and there are few who have not, while children, pelted each
other with the little round green seed-vessels during the time that the
fruit is in season. That they clung so tightly as not to be removed
without difficulty, we all knew, but we did not all know the cause. The
magnifying-glass, however, reveals the secret at once. The whole of the
surface is covered with little sharp prickles, curved like hooks, and
turned in all directions, so that, however it may be thrown, some of
them are sure to catch.
So readily do these hooks hold to anything which they touch, that if a
lady only sweeps her dress against a plant of Goose-grass, she is sure
to carry off a considerable number of the seed-vessels, and to waste
much time afterwards in picking them off.
The seed-vessel of the common Burdock, known popularly by the name of
Bur, is armed in a similar manner, but, as it is much larger, it is
easily avoided. Sheep suffer greatly from burs, which twist themselves
among the wool so firmly that it is hardly possible to remove them
without cutting away bur and wool together. As to a Skye terrier, when
once he gets among burs, his life is a misery to him (I was going to
say, a burden to him, but it would have looked like a pun).
Below, and on the left of the Galium-seed, are some spicules of the
Hymedesmia, a sponge which is found on the coast of Madeira. The
following account of it occurs in the _Intellectual Observer_, vol. ii.
p. 312:--
“FISH-HOOK SPICULÆ.--We have received from Mr. Baker, of Holborn, a
slide containing spicules of the _Hymedesmia Johnsonii_, which are
stated to be rare objects in this country. They have the form of a
double fish-hook, and on the inner surface of each hook is an
extremely sharp knife-edge projection, corresponding with a similar
and equally sharp projection from the inside of the shank.”
“These minute knife-blades are so arranged that in addition to
their cutting properties, they would act as barbs, obstructing the
withdrawal of the hook. The two hooks attached to one shank are not
in the same place, but nearly at right angles with one another, so
that when one is horizontal the other is vertical, or nearly so. A
magnification of four or five hundred linear does not in any way
detract from the sharp appearance of the knife-edges, and they may
take their place with the anchors of the Synapta as curious
illustrations of the occurrence in living organisms of forms which
man was apt to fancy were exclusively the products of his own
contrivance and skill.
“We presume that these hooks of the Hymedesmia answer the usual
purpose of spiculæ in strengthening the soft tissue, but they must
likewise render the sponge an awkward article for the Madeira
sea-slugs to eat.”
For an account and figures of the Synapta anchor-spicules see page 39.
* * * * *
WE now come to another modification of the hook. I presume that many of
my readers have heard of the practice called “snatching” fish, though I
hope that they have never been unsportsmanlike enough to follow it.
This plan, which is only worthy of poachers, consists in taking several
flights of treble or quadruple hooks, dropping them gently by the side
of the fish, and then, with a sudden jerk, driving them into any part of
its body which they may happen to strike. Most anglers have snatched
fish accidentally, but to do so intentionally is ranked among the worst
of an angler’s crimes, and is equivalent to cheating at cards, or
playing with false dice.
In some parts of the world, however, there are certain small fish which
are never taken in any other way, and, indeed, are raked out of the
water just as a gardener rakes dead leaves off the path or beds.
[Illustration: JAGUAR AND CLAW. FISH-RAKE. GAFF.]
In British Columbia there are certain lakes tenanted largely with small
fish which form a considerable portion of the natives’ diet. They swim
in vast shoals close to the surface of the water, and are captured by
veritable rakes, one of which is shown in the illustration. The points
of the rake are slightly curved, and very sharp, and so numerous are the
fish that when the native has struck his rake among the shoal, and drawn
it into the boat, he generally finds a fish on every tooth, while it
often happens that two or three are transfixed by the same tooth. A
sharp knock against the side of the boat shakes off the prey, and the
fisherman again strikes his rake into the shoal. By this simple mode of
fishing a couple of men will, in a few hours, load a canoe with small
but valuable fish.
Below the rake is the “Gaff,” an instrument, not to say a weapon, which
is indispensable when salmon or other large fish are to be caught. For
ordinary-sized fish a landing-net is sufficient, but no landing-net
could either receive or retain a salmon of any size.
Recourse is then had to the Gaff, which is simply a huge hook at the end
of a handle. The fish being “played” until it can be drawn within reach,
the gaff is slipped under it, struck into the side of the salmon, and by
its aid the fish is easily lifted out of the water.
* * * * *
ON the left hand of the illustration are two figures showing how the
principle of the fish-rake and gaff has been anticipated in Nature.
It is a well-known fact that the Jaguar feeds largely on fish, which it
catches for itself. It goes down to the river-side as close to the water
as possible, and waits patiently for its prey. As soon as a fish comes
within reach, the Jaguar stretches out its paw to the fullest extent,
and, with a stroke of the curved claws, hooks the fish on shore, just as
the Vancouver Islander does with his fish-rake, or the English angler
with his gaff.
Many persons have practically experienced the gaff-like powers of the
feline claw by the loss of their gold-fish. It is seldom safe to leave a
globe of gold-fish within reach of a cat. Nearly all cats are madly fond
of fish, and, in spite of their instinctive hatred of water, will hook
out the fish with their claws, and eat them. Indeed, there are several
instances on record where a cat has regularly caught fish, and brought
them home to its owner. Mr. F. Buckland gives an account of a
fisherman’s cat, which used to go out with her master, jump into the
sea, secure a fish, and then be lifted on board with her prey.
Above the Jaguar is drawn a single claw, so as to show the form of the
instrument by which the fish is captured.
ARMOUR.
We will now take the subject of Defensive Armour, by which warriors are
enabled to protect themselves against the offensive weapons of the
enemy.
As many readers will probably know, armour reached its greatest
development in the Middle Ages, when the knight was so completely cased
in steel that no weapon then in use could penetrate his panoply.
The head, body, and limbs were covered with steel plates curiously
articulated at the joints, so as to give freedom of motion, while
guarding the wearer from any ordinary weapon. A warrior might be beaten
from his horse by a mace, or struck down by a lance, or the horse itself
might be killed under him.
[Illustration:
LOBSTER.
ARMADILLO.
PICHICIAGO. CHITON.
PLATE AND SCALE ARMOUR
OF MIDDLE AGES.]
In either of these cases the fallen knight was not much the worse, until
a weapon called the “Misericorde,” or dagger of mercy, was invented.
This was a poniard with a very slender and very sharp blade, so
constructed that it could be driven between the joints of the armour,
and thus inflict a mortal wound. The Misericorde, however, was baffled
by the use of chain or scale armour under the plate-mail, and then the
only way of getting at the fallen knight was by breaking up the armour
with hammers which were made for this express purpose.
Perhaps the reader may wonder that any one should lie quietly and allow
himself to be so badly treated. The very strength of the armour,
however, which rendered its wearer unassailable by ordinary weapons,
involved so much weight, that when a knight had fallen, it was
impossible for him to rise, much less to mount a horse, without help.
Moreover, the first blow of a weighty hammer on the helmet would,
although it could not kill the wearer, cause such a jar to his brain as
partially, if not wholly, to stun him.
The rapidly increasing power of firearms soon caused armour to be laid
aside, and now the only remains of it are to be found in the helmets and
cuirasses worn by our dragoons.
* * * * *
THERE are few parts of the world where armour of some sort is not used.
Putting aside civilised or semi-civilised nations, we find that in most
cases, wherever there is war, there is armour of some kind. Sometimes it
is movable, and in that case is called a shield.
The most singular shields that I know are those made by the Australians,
which are so shaped that no one who did not know their use would take
them for shields. They are about three feet long, four inches wide at
the back, six inches or so thick in the middle, tapering towards the
ends, and coming to an edge in front. They are held by the centre with
one hand, so that they can be rapidly twisted from side to side, and so
serve to parry the spear or stop the boomerang. The weight of the shield
enables it to withstand the shock of the boomerang, which whirls through
the air with terrific force.
Several warlike savage tribes have, however, no armour of any kind, such
as the New Zealanders, the Samoans, and the Fijians.
Sometimes the armour is affixed to the body, and of such protection many
examples are to be found in various museums, among which the Christy
collection is pre-eminent.
Among the Polynesians cocoa-nut fibre was at one time employed as the
material for armour. It was twisted into small cords, and with these a
sort of armour was constructed, quite strong enough to resist any weapon
that an enemy of their own kind could bring against them. Sometimes this
armour was merely a belt wide enough to protect the abdomen, but
sometimes the whole body was defended, from the neck to the hips.
In the United Service Museum there is a very remarkable cuirass, which
is made of successive rows of seals’ teeth, each row overlapping the
other like the tiles of a house. It is very heavy, weighing quite as
much as a steel cuirass, and was probably quite as effective against the
primitive weapons which could be brought to bear upon it.
* * * * *
NOW for Natural Armour.
There are so many examples of armour, as furnished by Nature, that I can
only mention a few.
Any one who looks at a lobster, crayfish, prawn, or shrimp, must at once
see that in it lies the prototype of plate armour. That portion of the
lobster which is popularly called the head, and is scientifically known
as the “carapace,” is not jointed, and corresponds with the cuirass of
ancient or modern armour. Then comes the part called the “tail,” the
joints of which are exactly like those employed in the shoulders,
elbows, knees, and ankles of ancient armour. The lobster tail will again
be mentioned in connection with another branch of human art.
As for the heavy, ungraceful armour which was used in tilting, we have
an admirable example in the Trunk-fish of the tropical seas
(_Ostracion_), the whole of which is enclosed in a bony case, the fins
and tail protruding through openings in it. In fact, the scales, instead
of being separate, are fused together so as to form a continuous
covering. The Box-tortoise of South America is another good example, the
creature being furnished with bony flaps with which it covers the
apertures through which the head, legs, and tail are protruded, and so
is as impervious as the knight of old.
In the later ages of armour, the thighs, instead of being enclosed in
steel coverings with cuisses, were defended by a number of steel plates
called “tassets.” Now these tassets are exactly like the defensive
armour of the Armadillo’s back, and, though it is not likely that the
inventor of tassets should have seen an Armadillo, the fact still
remains, that Art has been anticipated by Nature.
Exactly the same principle is seen in that wonderful little animal, the
Pichiciago of South America, which is shown in the lower left-hand
figure of the illustration. This creature is not only furnished with
bony rings on the body like those of the Armadillo, but has likewise a
flap which comes over the hindquarters, and effectually defends it
against the attacks of any foe that might pursue it into its burrow.
In the lower right-hand corner of the illustration is seen a figure of a
Chiton, several species of which are common on most of our coasts. This
is one of the molluscs, which adheres to the rock just as limpets do.
But, whereas the shell of the limpet is all in one piece and inflexible,
that of the Chiton is composed of several pieces, which are arranged
exactly like the tassets of armour, and enable the Chiton to accommodate
itself to the inequalities of the rocks to which it is adhering.
The common Pill Millipede, which rolls itself up in a ball when alarmed,
is a familiar instance of similar defensive armour, and much the same
may be said of the Julus Millipede.
* * * * *
[Illustration: SCALES OF MANIS. SCALE-MAIL.]
We now come to Scale Armour, which is one of the earliest modes of
protecting the body, and the idea of which was clearly taken from animal
life. In Scale Armour, flat plates of metal, horn, or bone are sewn to a
linen or leathern vest in such a way that the scales overlap each other,
and so tend to throw off the blow of a weapon. One great advantage of
this armour is its lightness and flexibility, the former quality
allowing of more prolonged exertion than could be possible with the
heavy plate armour, and the latter rendering that exertion less
fatiguing to the limbs.
A glance at the preceding illustration will show how the scale armour of
the human warrior has been anticipated by Nature.
On the right hand is an example of ordinary scale armour, while on the
opposite side is a portion of a scaly surface. This figure represents
some of the scales of a Manis. These scales are wonderfully hard, and
scarcely to be penetrated. I have in my collection the skin of a
Short-tailed Manis, which had been kept for some time in an Indian
compound, but which made itself such a nuisance by its perpetual
burrowing, that its owner was forced to condemn it to death.
So he took a Colt’s revolver, and fired at it from a distance of a yard
or two. The only result was to knock over the Manis, which rolled itself
up, and appeared to be none the worse. A second and a third shot were
fired with similar results, and the last bullet recoiled upon the firer.
At last, the animal was killed by introducing the point of a dagger
under the scales, and driving it in with a mallet. The Manis itself is
given in the illustration on page 189.
[Illustration: SKIN OF SINGLETHORN. SCALE-MAIL.]
Again, the scales of most fishes afford excellent examples of scale
armour. I have selected one, the Japanese Singlethorn, on account of the
strength of the scales, each of which is deeply ridged and furrowed. The
reader will probably have noticed that the skin of the animal, into
which are inserted the bases of the scales, is analogous to the linen or
leathern foundation upon which the artificial scales are sewn.
Even feathers give a better protection than might be imagined from their
individually fragile structure. This is well shown in the case of
aquatic birds, whose feathers are very closely pressed together, each
overlapping the next, and set in regular order. Not only is the plumage
rendered water-tight, but it is able to resist a severe blow. This is
well known by sportsmen, who do not fire at ducks or geese while they
are approaching, knowing that their shot would only glide harmlessly
from the feather-mail of the bird.
They wait until the birds have passed, and then find no difficulty in
killing them, the shot penetrating under the feathers just as did the
dagger under the scales of the manis. Even the diminutive puffin, or
sea-parrot, as it is sometimes called, cares little for shot while it is
sitting on the rocks with closed wings and feathers pressed together.
When, however, it takes to flight, it can be killed without difficulty.
Perhaps some of my readers may be aware that the ancient Mexican
warriors wore armour made of feathers, which I presume must have been
arranged much after the fashion of those of a duck’s breast.
This remarkable Feather-mail is mentioned by Southey in his poem, “Madoc
in Aztlan.” In canto xviii, is recounted the single combat between Madoc
and Coanocotsin, the King of Aztlan. The contrasting armour and weapons
of each are graphically described, and especial mention is made of the
cuirass:--
“Over the breast,
And o’er the golden breastplate of the King,
A feathery cuirass, beautiful to eye,
Light as the robe of peace, yet strong to save;
For the sharp faulchion’s baffled edge would glide
From its smooth softness.”
Then, in the course of the combat, when the King has been grappled in
Madoc’s arms and forced to drop his buckler and club, the narrative
proceeds:--
“Which when the Prince beheld,
He thrust him off, and drawing back, resumed
The sword that from his wrist suspended hung,
And twice he smote the King. Twice from the quilt
Of plumes the iron glides.”
If such armour could in truth resist the weapons which have been
discovered, it must have been a wonderfully strong garment, for the
Mexican swords, though made of wood, are edged with flakes of obsidian,
which cuts like a razor. I have a number of these flakes, which have
evidently been intended for the edges of a sword, but have not been
used.
* * * * *
THERE is another kind of armour which is still used in some parts of the
world, and at one time was employed in this country. This is the Quilt
Armour, which is made by enclosing a thick layer of some fibre, such as
silk or cotton, between two pieces of fabric, and then sewing them
across and across, so as to keep the lining or stuffing in its place.
The eider-down quilts are familiar examples of such fabrics, and so are
the quilted petticoats, which are so comfortable in winter. Horsehair
and flock mattresses are made in a similar manner.
Insufficient as it may appear to be, the quilt armour, when well made,
is really proof against most weapons, even against firearms, as we shall
presently see. Being very much lighter than steel, it was easier for the
wearer, its chief drawback being that its extreme thickness gave it a
very clumsy and awkward look. Those who wore it, however, cared more for
their safety than their appearance, as was exemplified by James I., who
lived in perpetual fear of assassination, but who had a nervous dislike
to arms, whether offensive or defensive. He therefore wore a cuirass
quilted with silk, which answered every purpose of defence, while it did
not offend his nerves.
Perhaps the reader may remember that in “Peveril of the Peak” Sir Walter
Scott gives a ludicrous picture of the timid justice, his fears of the
Popish plot, his suit of quilted armour, and his “Protestant Flail” with
which he hits himself on the head instead of striking his supposed
enemy:--
“Some ingenious artist, belonging, we may presume, to the worshipful
Mercers’ Company, had contrived a species of armour of which neither the
horse armoury in the Tower, nor Gwynnap’s Gothic Hall, no, nor Dr.
Meyrick’s invaluable collection of ancient arms, has preserved any
specimen.
“It was called Silk-armour, being composed of a doublet and breeches of
quilted silk, so closely stitched, and of such thickness, as to be proof
against either bullet or steel, while a thick bonnet of the same
materials, with ear-flaps attached to it, and on the whole much
resembling a nightcap, completed the equipment, and ascertained the
security of the wearer from the head to the knee. Master Maulstatute,
among other worthy citizens, had adopted this singular panoply, which
had the advantage of being soft, and warm and flexible, as well as
safe. And he was sat in his judicial elbow-chair--a short, rotund
figure, hung round, as it were, with cushions, for such was the
appearance of the quilted garments--and with a nose protruded from under
the silken casque, the size of which, together with the unwieldiness of
the whole figure, gave his worship no indifferent resemblance to the
sign of the Hog in Armour, which was considerably improved by the
defensive garment being of a dusky orange colour, not altogether unlike
the hue of those half-wild swine which are to be found in the forests of
Hampshire.”
Roger Nutt gives as a reason for the security of quilted armour, that it
made the wearer look so ridiculous that no one could hit him for
laughing. The reader will probably remember that the sign of the Hog in
Armour was really a representation of the rhinoceros.
That such a cuirass is really impervious to ordinary weapons is shown by
the following anecdote:--During one of the late Indian wars a trooper
discharged his pistol close to the back of a fleeing horseman. The shot
produced no apparent effect, and the man rode off. Presently, however, a
thin cloud of smoke was seen to rise from his shoulders. The smoke
thickened, then burst into flame, and after riding at desperate speed in
hopes of overtaking his comrades, the unfortunate man fell from his
horse, and was miserably burned to death.
[Illustration: INDIAN RHINOCEROS. QUILTED ARMOUR.]
The fact was that cotton being cheaper than silk, he had wadded his
cuirass with cotton fibre. Had he chosen silk, he would have got off in
safety. Among the Chinese this cotton mail is largely used. In
consequence, many Chinese soldiers were found who had been burned to
death in exactly the same way as the Indian warrior.
Towards the south-western parts of Africa there is a nation called the
Begharmis. Their soldiers are mounted, and are all furnished with suits
of quilted mail, which fall below the knee as the rider is seated on his
horse. Not only is the rider thus defended, but the horse also, which is
covered with quilted armour like that of its rider, the appearance of
both being exceedingly grotesque.
* * * * *
THERE are several examples of such armour in the animal world, the
principal of which is the Indian Rhinoceros. Any one who has seen this
animal, or even a good portrait of it, will at once recognise the
parallel between the heavy folds of its thick skin and the padded flaps
of the quilted mail. The blubber with which the whale is so thickly
coated affords another example of the parallel between Nature and Art.
* * * * *
IN the days of ancient Rome there was a curious military manœuvre, by
which the defensive armour of individual soldiers might be made
collectively useful. This manœuvre was called Forming a Tortoise
(_testudinem facere_), and is thus described in Smith’s “Dictionary of
Greek and Roman Antiquities:”--
“The name of Testudo was also applied to the covering made by a close
body of soldiers, who placed their shields over their heads to screen
themselves against the darts of the enemy. The shields fitted so closely
together as to present one unbroken surface without any interstices
between them, and were so firm that men could walk upon them, and even
horses and chariots be driven over them.
[Illustration: TORTOISE. ROMAN TESTUDO.]
“A Testudo was formed either in battle, to ward off the arrows and other
missiles of the enemy, or, which was more frequently the case, to form a
protection to the soldiers when they advanced to the walls or gates of a
town for the purpose of attacking them.
“Sometimes the shields were disposed in such a way as to make the
Testudo slope. The soldiers in the first line stood upright, those in
the centre stooped a little, and each line successively was a little
lower than the preceding, down to the last, where the soldiers rested on
one knee. Such a disposition of the shields was called _Fastigata
Testudo_, on account of their sloping like the roof of a building.
“The advantages of this plan were obvious. The stones and missiles
thrown upon the shields rolled off them like water from a roof; besides
which, other soldiers frequently advanced upon them to attack the enemy
upon the walls. The Romans were accustomed to form this kind of Testudo
as an exercise in the games of the Circus.”
On the right hand of the illustration is shown a portion of a Testudo of
three ranks, taken from the Antonine column. On the left is an ordinary
Tortoise. Sometimes the Testudo was a covered machine on wheels, and
guarded above with a supplementary roof of wet hides arranged in scale
fashion, so as to prevent it from being set on fire by the besieged, and
to throw off the heavy missiles which were dropped upon it. Under cover
of this Testudo, the soldiers could either undermine the walls, or bring
a battering-ram to bear upon them, while the men who worked it were
safely under cover. As to the battering-ram itself, we shall presently
treat of it.
THE FORT.
As we have treated of one of the modes by which Forts were assaulted, we
will now come to the Fort itself.
The transitions in Fort-making are too curious to be omitted from the
present book. As soon as war became organized, a Fort of some kind was
necessary. The simplest mode of making a Fort was evidently to dig a
deep trench, and throw up the earth on the inside, so as to form a wall.
Let such a trench be square or circular, and there is a simple but
powerful Fort, by means of which a comparatively small garrison could
defend themselves against a superior force.
The Romans were great masters of this art, fighting as much with the
spade as the sword. So strong and thorough was the old Roman work that
many of their camps still remain, and will remain for centuries if man
does not deface them. Such, for example, are Cæsar’s camp, near
Aldershot, and the fine camp at Lyddington, in Wiltshire, almost every
detail of which is preserved. Roman camps are all constructed on the
same model, the general’s place, or Prætorium, being in the centre,
whence he issued his orders, and the commanders under him occupying the
corners. Thus, no matter how he might be shifted from one corps to
another, every Roman soldier knew his way about the camp without needing
to see it, and could tell at any moment where to find any officer.
[Illustration: ELK FORT.]
[Illustration: MOUND FORT.]
Other nations made their Forts circular, an example of which I lately
saw a few miles from Bideford, while others consisted of nearly parallel
lines, enclosures, and demi-lunes, like those wonderful dykes near
Clovelly, which occupy more than thirty acres of land. One of the
circular Forts is shown on the right hand of the illustration.
As time went on, stone took the place of earth, and the principal object
of the builder was to give considerable thickness below, so as to resist
the battering-ram, and great height both to walls and towers, so as to
be comparatively out of the reach of the arrows and other missiles of
the besiegers.
For awhile, such castles were impregnable, and the owners thereof were
the irresponsible despots of the neighbourhood, recognising no law but
their own will, robbing, torturing, and murdering at pleasure, and
setting the king at open defiance. When, however, the tremendous powers
of artillery became developed, the age of stone castles passed away.
Height was found to be equivalent to weakness, as the strongest tower in
existence could be knocked to pieces in an hour or two, and do infinite
harm within the fortress by its falling fragments.
Fortification then returned to its original principles. Earth took the
place of stone or brick; and at the present day, instead of erecting
lofty walls and stately towers, the military engineer sinks his
buildings as far as he can into the ground, and protects them with banks
of simple earth, which is found to be the best defence against heavy
shot. There is no masonry in existence that will endure the artillery
fire of the present day, and even the solid rock can be knocked to
pieces by it. But an earth-mound is a different business, and will
absorb as many shot and shell as can be poured into it, without being
much the worse for it. See, for example, the Proof-mound at Woolwich,
which receives the shot of guns as they are being proved. Now, this
mound has undergone perpetual battering for many years, and is as strong
as ever. The same thing may be said of the celebrated Mamelon before
Sebastopol.
* * * * *
SO much for the Fort made by the hand of man. We now come to that which
is formed by the feet of animals.
The Elk, or Moose, an inhabitant of Northern Europe, finds itself in
great danger during the winter, the wolves being its chief enemies. At
certain times of the year there comes a partial thaw during the day,
followed by a frost at night. The result is, that a slight cake of ice
forms on the surface of the snow, too slight to bear the weight of so
heavy an animal, and strong enough to cut the legs of the elk as it
ploughs its way along. Now, the wolves are sufficiently light to pass
over the frozen surface without breaking it, and accordingly, they can
easily run down and secure the elk.
In order, therefore, to counteract the wolves, a number of elks select a
convenient spot where they can find food, and unite in trampling the
snow down so as to sink themselves nearly to their own height below its
surface. The wolves never dare attack an Elk-yard, as this enclosure is
termed. In the first place, they are always haunted with suspicions of
traps, and do not like the look of the yard; and in the next place, if
some of the wolves did venture within the fort, the elks would soon
demolish them with hoofs and horns. One of these Elk-yards is seen on
the left hand of the illustration.
WAR AND HUNTING.
CHAPTER VII.
SCALING INSTRUMENTS.--DEFENCE OF FORT.--IMITATION.--THE FALL-TRAP.
Scaling-forks.--The Climbing-spur and its Use.--Larva of the
Tiger-beetle.--Hooks of Serpula.--Mr. Gosse’s Description.--Falling
Stones.--A Stone rolling down a Precipice.--The Polar Bear and the
Walrus.--Imitation.--The Polar Bear and the Seal.--The Esquimaux
Hunter “Seal-talking.”--Enticing Mother by means of Young.--The
Fall-trap and its Variations.--The Schoolboy’s
“Booby-trap.”--Curious Mode of killing Elephants.--The
Elephant-spear.--The Hippopotamus-trap of Southern Africa.--The
Mangrove and its Seeds.--The Spring-gun and Spring-bow.
Before dismissing the subject of the Fortress, we will glance at the
Attack and Defence, as seen in Nature and Art.
SCALING INSTRUMENTS.
We have already seen how the Battering-ram could be worked against the
walls of a fort, or how the assailants could scale them by means of the
Testudo. There must, however, be occasions when it would be impossible
to bring together a sufficiently large body of men to form the Testudo,
or even to place ladders, and in such instances it would be necessary
that each soldier should be furnished with an instrument by which he
could haul himself up the wall.
There are many examples still extant of such weapons, which were called
“Scaling-forks,” and their general appearance may be known by the two
right-hand figures of the cut. The handles of these weapons were very
long, and by them the soldier hauled himself to the top of the wall. In
some of these instruments the shafts were armed with projecting pegs,
set at regular intervals, so that they acted as the steps of a ladder,
and rendered the ascent comparatively easy.
Many of the long-handled partisans, such as the well-known Jedwood axe,
were furnished with a hook upon the back of the blade, so that the
weapon served the purpose of a scaling-fork as well as a battle-axe.
The Scaling-fork (German _Sturmgabel_), which is shown on the right hand
of the illustration, was in use somewhere about A.D. 1500. That which is
shown next to it is about a hundred years later.
[Illustration:
WALRUS TUSKS. LARVA OF TIGER-BEETLE. CLIMBING-SPUR. SCALING-FORKS.
HOOKS OF SERPULA.]
Demmin, from whose work these figures are taken, mentions that at the
siege of Mons, in 1691, the grenadiers of the elder Dauphin’s regiment
stormed the walls under the command of Vauban, and, by means of the
Scaling-fork, carried the breastwork, which they assaulted. As a mark of
honour to these gallant men, Louis XIV. ordered that the sergeants of
the regiment should carry scaling-forks instead of halberds, which had
been the peculiar weapon of the sergeant until comparatively late days,
just as the spontoon, or half-pike, was the weapon of the infantry
officer from A.D. 1700 to A.D. 1800, or thereabouts.
The English student will remember that in the writings of Sterne,
Fielding, and Smollett the half-pike is frequently mentioned as the
weapon of a subaltern officer. Demmin states that the last spontoons
used in France were carried by the French Guards in 1789.
* * * * *
PERHAPS the Climbing-spur may be familiar to some of my readers, and
bring back a reminiscence of boyhood. There is nothing more tantalising
to a boy than to see a hawk, or magpie nest at the top of a tree which
is too large to be climbed in the ordinary way, and which has no
branches within many feet of the ground. However, boyish ingenuity has
brought almost any tree within the power of a bird’s-nester by the
invention of the Climbing-irons.
These are made so as to pass under the foot like a stirrup, and can be
secured to the leg by leathern straps, the hooks being, of course, on
the inside of the leg. The cut represents the Climbing-iron of the right
leg. By means of these instruments, a very large tree can be mounted,
the irons being struck firmly into the bark, and the legs moved
alternately, and not in the usual manner of climbing. Sometimes the hook
of the Climbing-iron is terminated by a single instead of a double
point, but the principle is the same in all.
* * * * *
WE will now look for similar examples in Nature.
On the right of the left-hand group is shown the larva or grub of the
common Tiger-beetle, which is itself a curious creature.
It lives in perpendicular burrows, feeding upon those insects which come
within its reach. Its usual position is at the upper part of the burrow,
with its jaws widely extended, so as to snap up any insect that may
venture too near.
When it has secured its prey, it seeks the bottom of its burrow, makes
its meal in quiet, and reascends. How it does so we shall soon see.
Towards the end of the body, one of the segments is much enlarged, and
has a bold prominence upon the back. On the summit of this prominence
there are two horn-like hooks, shaped as seen in the illustration. These
hooks are used exactly like the boy’s climbing-spurs, the alternate
elongation and contraction of the body answering the same purpose as the
movements of the boy’s legs. When the larva has seized its prey and
wishes to retreat, all that it has to do is to withdraw the hooks,
straighten the body, and down it falls by its own weight.
* * * * *
IN the nautical branch of this subject I have already treated of the
curious pushing-poles by means of which the Serpula protrudes itself
from its tube. As all must have noticed who have seen these creatures
alive, the Serpula protrudes itself very slowly, but flies back into its
tube with such velocity that the eye can scarcely follow its movements.
Its difference of motion shows that there must be a difference in the
means by which these movements are produced.
Referring to the illustration on page 45, the reader will see that the
instruments with which the Serpula propels itself are used just after
the fashion of punt-poles, and cannot act with any great swiftness.
When, however, the creature wishes to withdraw itself, it employs a
curious apparatus, consisting of many rows of little hooks. The points
of these hooks readily catch against the lining of the tube, and by
their aid the worm jerks itself back with wonderful celerity.
Three rows of these hooks are shown next to the Tiger-beetle larva.
The structure of these remarkable organs is elaborately described by Mr.
Gosse in his “Evenings with the Microscope:”--
“If you look again at this Serpula recently extracted, you will find
with a lens a pale yellow line running along the upper surface of each
foot, transversely to the length of the body. This is the border of an
exceedingly delicate membrane, and, on placing it under a high power
(say six hundred diameters), you will be astonished at the elaborate
provision here made for prehension.”
“This yellow line, which cannot be appreciated by the unassisted eye, is
a muscular ribbon, over which stand edgewise a multitude of what I will
call combs, or rather subtriangular plates. These have a wide base, and
the apex of the triangle is curved over into an abrupt hook, and then
this cut into a number (from four to six) of sharp and long teeth.”
“The plates stand side by side, parallel to each other, along the whole
length of the ribbon, and there are muscular fibres seen affixed to the
basal side of each plate, which doubtless give it independent motion.
“I have counted one hundred and thirty-six plates on one ribbon. There
are two ribbons on each thoracic segment, and there are seven such
segments. Hence, we may compute the total number of prehensile comb-like
plates on this portion of the body to be about one thousand nine
hundred, each of which is wielded by muscles at the will of the animal;
while, as each plate carries on an average five teeth, there are nearly
_ten thousand teeth_ hooked into the lining membrane of the cell, when
the animal chooses to descend.”
“Even this, however, is far short of the total number, because long
ribbons of hooks of a similar structure, but of smaller dimensions, run
across the abdominal segments, which are more numerous than the
thoracic. No wonder, with so many muscles wielding so many
grappling-hooks, that the descent is so rapidly effected.”
Lastly, we come to the Walrus, whose strangely elongated upper canine
teeth can be used for just the same purposes as the scaling-fork or
climbing-spur. As, however, reference has already been made to these
tusks, in connection with another department of this work, there is no
necessity for occupying space with a second description.
DEFENCE OF FORT.
So much for attack; now for defence.
The simplest mode of defending a fort, or even a mountain pass, is by
throwing or rolling rocks and heavy stones against the enemy.
Simple as it may appear, it is a very effective one, as can be well
understood by those who have rolled a huge stone down a long and steep
slope. The stone goes gently enough at first, but rapidly gains speed,
until at last it makes great bounds from the earth, tearing and crashing
through everything as if it had been shot from a cannon.
I have seen a stone which was too heavy to be lifted, and had to be
prised over the edge with levers, spring completely through the topmost
branches of a high tree, scattering the boughs in all directions, and
then, alighting on another stone, split into many fragments, just like
the pieces of a burst shell. That one stone would have swept off a whole
party of soldiers had they encountered it while trying to ascend the
slope.
This invention has also been anticipated in Nature.
Putting aside the obvious reflection that the most primitive warriors
must have noticed the effects of stones falling over a precipice, we
have, in Captain Hall’s “Life with the Esquimaux,” a curious account of
the Polar Bear and its mode of killing the Walrus. Gigantic as is this
animal, and terrible as are its tusks, the Polar Bear will sometimes
attack it in a very singular manner. The Bear springs on a sleeping
Walrus, and clings to its shoulders with one paw, and with repeated
blows from the other, fractures its skull.
Still, the combat is sure to be a severe one, and so the Polar Bear
will, if he can, secure his prey by some other method.
“The natives tell many most interesting anecdotes of the Bear, showing
that they are accustomed to watch his movements closely. He has a very
ingenious method of killing the Walrus.
[Illustration: BEAR KILLING WALRUS.]
[Illustration: WARRIORS DEPENDING A PASS.]
“In August, every fine day, the Walrus makes its way to the shore, draws
its huge body upon the rocks, and basks in the sun. If this happen near
the base of a cliff, the ever-watchful Bear takes advantage of the
circumstance to attack his formidable game in this way. The Bear mounts
the cliff, and throws down upon the animal’s head a large rock,
calculating the distance and the curve with astonishing accuracy, and
thus crushing the thick, bullet-proof skull.
“If the Walrus is not instantly killed, or simply stunned, the Bear
rushes down to it, seizes the rock, and hammers away at the head until
the skull is broken. A fat feast follows. Unless the Bear is very
hungry, it eats only the blubber of the walrus, seal, and whale.”
IMITATION.
As is the case with the Norwegians, the Esquimaux have the greatest
respect for the intellectual as well as the bodily powers of the Bear,
and avowedly imitate it in its modes of hunting. One of these methods
will now be mentioned.
It must first be premised that the Seal is a most wary animal, and when
it lies down on the shore to sleep, it takes its repose by snatches,
lifting up its head at very short intervals, looking all round in search
of foes, and then composing itself to rest again. To approach so
cautious an animal is evidently a difficult task, but the Bear is equal
to it. The following is Captain Hall’s account:--
“From the Polar Bear the Innuits (_i.e._ Esquimaux) learn much.
[Illustration: POLAR BEAR HUNTING SEAL.]
[Illustration: ESQUIMAUX HUNTING SEAL.]
“The manner of approaching the Seal, which is on the ice by its hole,
basking in the sunshine, is from him. The Bear lies down and crawls by
hitches towards the Seal, ‘talking’ to it, as the Innuits say, until he
is within striking distance, when he pounces upon it with a single jump.
The natives say that if they could ‘talk’ as well as the Bear, they
could catch many more Seals.
“The procedure of the Bear is as follows.
“He proceeds very cautiously towards the black speck, far off on the
ice, which he knows to be a Seal. When still a long way from it, he
throws himself down and hitches himself along towards his game. The
Seal, meanwhile, is taking its naps of about ten seconds each,
invariably raising its head and surveying the entire horizon before
composing itself again to brief slumber.
“As soon as it raises its head, the Bear ‘talks,’ keeping perfectly
still. The Seal, if it sees anything, sees but the head, which it takes
for that of another Seal. It sleeps again. Again the Bear hitches
himself along, and once more the Seal looks around, only to be ‘talked’
to and again deceived. Thus the pursuit goes on until the Seal is
caught, or till it makes its escape, which it seldom does.”
It is remarkable that while this “talk” is going on, the Seal appears to
be charmed, raises and shakes its flippers about, rolls over on its side
and back, as if delighted, and then lies down to sleep.
Now, the Esquimaux hunters imitate, as nearly as they can, the
proceedings of the Bear, but are not so successful. Captain Hall
mentions several instances where the native hunter failed even to come
within gunshot without alarming the Seal, which instantly plunged into
its hole and was lost.
* * * * *
THE same author mentions another instance where the Esquimaux hunter has
copied the Bear.
[Illustration: POLAR BEAR CATCHING SEAL, ETC.]
When an Esquimaux hunter catches a young Seal, he takes care not to kill
it at once, as he wishes to use it as a decoy. He ties a long line round
one of the hind flippers, and then drops the little Seal into the hole
through the ice by which it enters and leaves the water. The struggles
of the young are nearly sure to attract the mother, and when she has
discovered its condition the young Seal is cautiously drawn up on the
ice. The mother follows, too intent on rescuing her young to think about
herself, and, as soon as she is within reach, she is struck with the
harpoon.
The Polar Bear, however, preceded the Esquimaux in this mode of hunting.
The young Seal lives in a hemispherical dwelling scooped out of the
snow, and communicating with the water by means of a hole through the
ice. This dwelling will be described and figured when we come to the
subject of Architecture.
Finding out, by scent or some other means, the habitation of the young
Seal, the Polar Bear leaps upon the snow, bringing his feet together,
and with his enormous weight breaking through the roof of the dwelling.
He instantly captures the young Seal before it can make its escape.
Then, driving the talons of one paw into its hind flipper, he lets it
into the hole, and allows it to flounder about in the water. When the
mother is attracted to her young, he draws his prey slowly up on the
ice. The anxious mother follows, and is at once secured by the talons of
the other foot, as is represented in the illustration.
THE FALL-TRAP.
This is a stratagem which is often employed in War and Hunting, though
its use is mostly confined to the latter. Schoolboys often avail
themselves of this principle when they wish to play a practical joke,
and to amuse themselves by setting a “Booby-trap.” This trap is easily
manufactured, and consists of a partially opened door, with a basin or
jug of water balanced upon it. The natural result is, that any one who
opens the door without proper precautions receives the jug and its
contents upon his head, and is thoroughly drenched.
On the right hand of the illustration is seen a curious spear, the butt
of which, instead of being lighter than the head, is very much heavier.
The weight, however, is exactly where it is wanted, and indeed, in
actual use, is trebled by a mass of tenacious clay, kneaded upon it.
This figure is taken from a very perfect specimen in my own collection.
It is an African weapon, not used for war, but for hunting, and, as far
as I know, exclusively employed against the elephants. These animals
have a way of forming roads or tracks for themselves through the woods,
very much like those almost invisible paths which are made by the
half-wild sheep of the great Wiltshire Downs, except that they traverse
thick forests instead of broad downs.
The native hunters know all the elephant paths, and if a herd of
elephants be seen approaching, the path which they will take is
tolerably certain.
[Illustration: MANGROVE SEEDS.]
[Illustration: HIPPOPOTAMUS TRAP AND ELEPHANT SPEAR.]
Armed with this knowledge, the native hunters climb the trees, and seat
themselves on the branches which overhang the path, each hunter being
supplied with one of these spears. As the elephants pass beneath him,
the experienced hunter selects a bull elephant with good tusks, and,
taking a careful aim, drops the spear on its back.
On receiving the stroke, the elephant rushes off in mixed terror and
rage. As the animal uses the legs of each side alternately, it sways its
huge body from side to side at every step. With each movement, the spear
also sways about, its weighted end giving it such a leverage, that the
sharp edges of the head cut the poor animal to pieces.
* * * * *
ANOTHER kind of Fall-trap, which is common in many parts of Southern
Africa, is not dependent upon the skill of the hunter, but, like the
“booby-trap” above mentioned, is set in motion by the victim.
A figure of this trap is given in the illustration.
If the native hunter can find a spot where the Hippopotamus path passes
under an overhanging branch, he makes a simple but most effective trap.
He takes a heavy log of wood, and into one end of it he drives a
spear-point. The log is then hung with its point downwards to the
branch, the rope which is connected with its trigger or catch being
stretched across the path at a few inches from the surface of the
ground, and carried at right angles across the path.
The Hippopotamus takes no notice of the cord, which is usually made of
one of the creepers or “bush-ropes” that are so common in hot countries.
No sooner, however, does its foot strike the cord, than the trigger is
released, and down falls the heavy log, driving its iron point deeply
into the back of the victim. Even if the weapon were simple iron, such a
wound must be mortal, but, as it is almost invariably poisoned, the
wounded animal can scarcely travel forty or fifty yards before it lies
down and dies.
One of these traps is shown in the illustration. In the foreground is
shown the Fall-trap, pointed with iron, and weighted with large stones
at the lower end, so as to bring it down with more force, and to prevent
it from falling transversely.
The Spring-gun, once so formidable a protector of our coverts, was
managed in a similar manner, except that the missile was discharged
horizontally, and not vertically. The gun, loaded with shot, was fixed
some eighteen inches from the ground, and a long and slight wire
fastened to the trigger. The opposite end of the wire was made fast to a
tree or other fixed object, and, as the gun was directed on the line of
the wire, it is evident that any one who stumbled against it would
discharge the gun, and receive the contents in his legs.
In France the gun was generally loaded with little pieces of bay salt,
and I very much pity the unfortunate poacher who came across one of
these guns. The pain would prevent him from escaping, and I think that
the hardest-hearted of game preservers could not bring himself to
prosecute a man who had already suffered so much.
Of a similar character are the Spring-bows which were once common in
this country, and are still used in various parts of Asia. A bow and
arrow are substituted for firearms, and the bow, after being drawn by
the united efforts of several men, is held in its position by a stick,
one end of which presses against the centre of the bow, and the other
against the string.
A large arrow is then placed on the bow, and a cord is tied to the
middle of the stick, led forwards in a line with the direction of the
arrow, and fastened, as in the case of the spring-gun. As soon as the
line is struck, the stick is jerked from its place, and the arrow is
discharged, piercing the body of the trespasser. Tigers, bears, and
leopards are the usual victims of this trap.
* * * * *
IT is remarkable that in the same country there is a production of
Nature which may in all probability have given to the native hunter the
idea of the Fall-trap. This is the Mangrove-tree, which is remarkable
for the wonderful extent of ground which it will cover, and the nearly
impenetrable thickets which it forms. In the present part of the work we
have nothing to do with the aërial roots, several of which are shown in
the illustration, and only restrict ourselves to the Seeds, and the
curious manner in which they are planted by Nature.
In the illustration, on the left hand, the growth of the Mangrove is
seen. The drawing is taken from a sketch by the late Mr. Baines, and
generously placed at my disposal, as were all his drawings and journals.
The Mangrove is a wet-loving tree, never flourishing unless rooted in
mud; and whether the moisture of the mud be attributable to fresh or
salt water seems to make little difference to the Mangrove, which, of
the two, appears to prefer the latter. Now, the seeds of the Mangrove
look very much like elongated skittles, except that one end comes to a
sharp point. As they hang on the tree, the point is downwards. When they
are ripe, they fall from the branch, and by their own weight are driven
deeply into the mud, where they develop roots and leaves, and become the
progenitors of the future Mangrove race.
I cannot but think that the native hunter, having seen the tremendous
force with which the Mangrove seed buries itself in the mud, has applied
the same principle to a weapon which shall bury itself in the body of an
elephant.
WAR AND HUNTING.
CHAPTER VIII.
CONCEALMENT.--DISGUISE.--THE TRENCH.--POWER OF GRAVITY.--MISCELLANEA.
Concealment needed in Modern Warfare.--Concealment by
Covering.--Masking Guns.--Birnam Wood.--The Reduvius.--The
Cuckoo-spit and the Spider-crab.--Concealment by
Disguise.--Stratagem of the Barea.--Complete Deception.--Larva of
Geometra.--The Leaf-insect.--The Luppet-moth.--The Ptarmigan and
the Ermine.--Principle of the Trench.--The Hunter’s “Skärm.”--The
Wax-moth or Galleria-moth, and its Tunnel.--Fate of a
Collection.--The Termites and the Travelling Ants of South
America.--The Power of Gravity.--The Battering-ram and its
Force.--Miscellanea.--War by Suffocation.--The Stink-pot.--The
Chili-plant.--The Sulphur-room.--The Bombardier-beetle.--The
Bullet-making Machine and the Silkworm.
CONCEALMENT.
We will first take Concealment by means of Covering.
If History repeats herself, so does Warfare. I have already shown the
repetition of History in the Fortress--I shall now show it in the Field.
In former days, when arms of precision were not invented, concealment
was not needed. No soldier ever was visited with a dream so wild as that
of taking definite aim at the enemy, and reserving the fire until the
aim was certain. I have in my collection several of the French and
English muskets used about the time of Waterloo, and, though a fair
rifle-shot, would not engage to hit a haystack with either of them at a
distance of a hundred yards. With the Snider or Martini-Henry in the
hands of a skilful adversary, he would be a bold man who would offer
himself for a target at a thousand yards. Indeed, if the first shot
happened to miss, the marksman would be tolerably sure to notice the
failure, and to correct his aim with fatal certainty.
In those days, therefore, concealment was rather ridiculed than praised,
the power of the new arm not being as yet appreciated. I well recollect,
in the earliest days of the Volunteer movement, hearing a Volunteer
captain declare, amid the cheers of his company, that “he had never
sneaked behind a tree in all his life, and was not going to begin now.”
In the present day, the power of the missile has been developed with
such astounding rapidity, that to be exposed to the fire of rifles or
cannon is almost certain death. Indeed, the only safety of the defence
lay in the fact that the smoke soon rendered very accurate shooting
impossible at long ranges, and that at short ranges, if a man got a
bullet through his body, it mattered little to him whether the missile
were a spherical musket-ball or a conical rifle-bullet.
[Illustration: REDUVIUS (MAGNIFIED).]
[Illustration: CUCKOO-SPIT.]
[Illustration: SPIDER-CRAB.]
[Illustration: MASKING GUNS.]
[Illustration: BIRNAM WOOD.]
Just, then, as forts have latterly sunk into the earth for the purpose
of strength, so have our modern soldiers found that the true principle
of modern warfare is never to lose sight of the enemy, and never to
allow the enemy to see yourself or the disposal of your troops.
Everything must be revealed to the commander-in-chief, everything must
be concealed from the enemy.
In the late Franco-German war the principle of concealment was largely
used, and when cannon were brought into the field by the Germans for the
purpose of attacking fortresses, they were always hidden under branches
of trees, so that the enemy should not distinguish them from the
ordinary features of the country, and that the sparkle of the sunbeams
upon them might not be seen.
It would be almost superfluous to remind the reader of Malcolm’s
stratagem when besieging Dunsinane Castle:--
“Let every soldier hew him down a bough,
And bear’t before him; thereby shall we shadow
The numbers of our host, and make discovery
Err in report of us.”
Precisely similar modes of concealment are to be found in the animal
world.
There is a certain insect belonging to the Heteroptera, and
scientifically named _Reduvius personatus_. I am not aware whether it
has any popular name. It is insectivorous, and ought to be welcomed in
houses, as it is particularly fond of the too common bed-bug. So
carnivorous are these insects that one of the Reduviidæ killed and
sucked a companion of her own sex, her own mate, and, after only a few
days’ fast, her own young, and then sucked her own eggs.
During its larval and pupal stages of existence, the Reduvius covers its
body and limbs with dust and any other refuse which it can find. In this
manner it disguises its form so completely that it scarcely looks like
an insect. Occasionally it seems to be dissatisfied with its coat of
dust, throws it off, and sets to work at a new one.
One of these creatures, as it appears when covered with its dusty
coating, is seen in the upper left-hand corner of the illustration. It
is slightly magnified.
Below the Reduvius is the common Cuckoo-spit (_Aphrophora spumaria_),
whose frothy masses are so plentiful in our hedgerows and gardens.
If one of these masses be carefully opened, there will be found in it a
little green creature with small, round, dot-like eyes. This is either
the larval or pupal state of the Frog-hopper, as the insect is called
in its perfect state, from its habit of taking long and sudden leaps
when alarmed.
I well remember my delight when, as a child, I set to work at examining
these froth-masses, and succeeded in tracing the insect through all its
changes. The froth is derived from the sap of the tree, which is sucked
through the proboscis, passed through the digestive organs, and then
ejected in a succession of little bubbles. After awhile a little drop of
clear liquid is seen to collect at the bottom of the froth, to increase,
and then to fall, when another immediately begins to be formed. One
species of Cuckoo-spit, which inhabits Madagascar, acts almost like a
siphon on the tree, and pours out large quantities of clear water during
the hottest part of the day.
Within this froth-mass the insect lies concealed, and, though utterly
helpless, is safe from most of the enemies that would attack it if it
were left exposed.
Beneath the Cuckoo-spit is the common Spider-crab, sometimes called the
Thornback-crab, from the numerous spines with which its body is covered.
Its scientific name is _Maia squinado_.
When the Spider-crab attains to a tolerable size, its rough surface
forms attachment for various marine beings, chiefly those belonging to
the zoophytes. In some cases these zoophytes grow to such a size that
the Crab is completely covered by them, and its original shape
effectually concealed. When one of these creatures is seen in a living
state it presents the curious spectacle of a large bunch of zoophytes
and corallines moving about from place to place without any perceptible
limbs, the whole of the surface of the Crab being covered with
extraneous growths.
DISGUISE.
Next comes concealment by means of Disguise.
On the right hand of the accompanying illustration is shown a singular
mode of concealment adopted by the Barea, a warlike and predatorial
tribe of Abyssinia. When Mr. Mansfield Parkyns was resident in Abyssinia
he fell in with the Barea, through whose country he had to pass.
“Scarcely had we passed the brook of Mai-Chena when one of our men, a
hunter, declared that he saw the slaves. Being at that time
inexperienced in such matters, I could see nothing suspicious. He then
pointed out to me a dead tree standing on an eminence at a distance of
several hundred yards, and charred black by last year’s fire.” Here I
must explain that in Abyssinia, as in several other parts of the world,
the ground is annually, cleared of its superabundant vegetation by
setting fire to it, and allowing the flames to burn themselves out.
[Illustration: LEAF-INSECT.]
[Illustration: PTARMIGAN.]
[Illustration: CATERPILLAR OF GEOMETRA.]
[Illustration: LAPPET-MOTH.]
[Illustration: BAREA STRATAGEM.]
“However, all I saw was a charred stump of a tree and a few blackened
logs or stones lying at its feet. The hunter declared that neither the
tree nor the stones were there the last time we passed, and that they
were simply naked Barea, who had placed themselves in that position to
observe us, having no doubt seen us for some time, and prepared
themselves.
“I could scarcely believe it possible they could be so motionless, and
determined to explore a little. The rest of the party advised me to
continue quietly in the road, as it was possible that, from our
presenting a rather formidable appearance, we should pass unmolested;
but so confident was I of his mistake, that, telling the rest to go on
slowly, as if nothing had been observed, I dropped into the long grass
and stalked up towards them.”
“A shot from my rifle at a long distance (I did not venture too close)
acted on the trees and stones as powerfully as the fiddle of Orpheus,
but with the contrary effect; for the tree disappeared, and the stones
and logs, instead of running after me, ran in the opposite direction.”
“I never was more astonished in my life, for so complete was the
deception that even up to the time I fired I could have declared the
objects before me were vegetable or mineral--anything, indeed, but
animal. The fact was that the cunning rascals who represented stones
were lying flat, with their little round shields placed before them as
screens.”
This stratagem is shown on the right hand of the illustration.
* * * * *
ON the left are a few of the innumerable instances in Nature where
Concealment is obtained by imitation.
The three examples which are here given are familiar to all
entomologists.
The upper figure represents two of the Geometra or Looper Caterpillars,
as they appear when at rest, and affixed to a twig. This appears to be a
singular attitude of rest, but it is one in which they delight, and in
which they remain for hours together, the claspers at the end of the
body tightly grasping the branch, and the whole body held out so
straight and motionless that it is hardly possible to believe that a
veritable twig is not before the eye. The colour is that of the twig,
and the different segments of the body look exactly like the little
irregularities and projections of a young twig.
I have more than once seen a novice in entomology unable to distinguish
these larvæ, even when the branch was pointed out, and there were
several upon it.
Just below the Loopers, and on the left hand of the illustration, is
shown the well-known Leaf-insect (_Phyllium_). These strange beings have
the elytra and the flattened appendages of the legs so exactly like
leaves that the most experienced eye can scarcely distinguish them from
the leaves among which they are placed. Even when they have been on a
small plant, such as a myrtle in a flower-pot, I have had the greatest
difficulty in finding them, and have seen people examine the plant, and
then go away declaring that no insects were on it.
On the right hand, and just below the looper caterpillar, is the common
Lappet-moth of this country, shown in its position of rest.
When it assumes this attitude, it looks exactly like a withered leaf,
the resemblance extending not only to the form, but the colour. All
entomologists are familiar with many similar examples in insect life.
The common Tortoise-shell Butterfly, for example, has a way of settling
on patches of red soil, with which it harmonizes so well that it can
hardly be seen. The various moths, also, are in the habit of resting on
tree-bark, palings, and other objects, to which they instinctively know
that they assimilate in hue. Many a beginner in entomology will pass a
wooden fence or a wall, and not see an insect on either, while an adept
will follow him and take twenty or thirty good specimens.
The last figure in the illustration represents a Ptarmigan (_Lagopus
vulgaris_) in its winter dress. These birds have two differently
coloured dresses, one for summer and the other for winter, and both
adapted for concealment by imitation. In the former dress it is mottled
with various shades of blackish brown, yellow, and white. As the bird is
in the habit of settling among the grey lichen-covered stones on the
sides of rocky hills, these colours harmonize so exactly with them that
a Ptarmigan may almost be trodden upon before it is perceived.
In the winter, when the snow covers the whole country with one uniform
sheet of white, except where the wind blows the snow aside, and exposes
the underlying stones, the Ptarmigan assumes a different plumage, being
almost entirely white, except a black streak over the eye, and the outer
feathers of the tail, which are also black. Thus the bird becomes almost
indistinguishable from a snow-covered stone, especially as it has a
habit of squatting motionless and silent when it takes alarm.
The reader may, perhaps, remember that the common Stoat also has a
summer and winter dress. The ordinary colour is rich reddish brown
above, and white beneath, with a black tip to the tail. In the severe
winters of Northern Europe the Stoat exchanges his ruddy coat for one of
pure white, and is then known by the name of Ermine. It is remarkable
that in the winter dress both of the Ptarmigan and Stoat the tail is
black, while the rest of the coat is white.
THE TRENCH.
We now come to a third mode of concealment in war, namely, that which is
obtained by means of Trenches or Pits.
Even in hunting the pit or partial trench is largely used. In Southern
Africa the hunter often employs such a trench, called technically a
“Skärm.” It is very simple in idea, and easily made, being based on the
principle that lions, elephants, &c., look for their assailants on the
level of the earth, and seldom, if ever, look above or below it.
Accordingly the hunter, having marked some pool or lake whereunto the
wild animals resort at night to quench their thirst, chooses a
convenient spot, and there digs a trench some seven feet in length and
four deep, and covers it in with stout tree-branches and logs of various
size. The whole is roofed in with sods, and the only entrance is at one
end.
Here the hunter sits and waits, and, as his ear is on a level with the
surface of the ground, he can hear at a considerable distance sounds
which would have escaped him had he been erect.
Waiting for a favourable opportunity, as the various beasts come to
drink, the hunter chooses one, takes careful aim, and fires one of his
heaviest guns. It is but seldom that the rest of the animals charge in
the direction of the Skärm, but even if they do, the hunter is quite
safe under the shelter of his strong roof, which is able to resist even
the heavy tread of an elephant.
[Illustration: Galleria-Moth (Larva).]
[Illustration: Military Trench.]
In modern warfare, and especially during sieges, the trench is largely
used, and is constructed on the most scientific principles, so as to
shelter the assailants, while enabling them to proceed nearer and nearer
to the fortress. A portion of one of these trenches is shown in the
right hand of the illustration.
* * * * *
ON the opposite side of the same illustration is shown the same
principle as carried out in Nature.
There is a certain little insect, called the Wax-moth, or Galleria-moth
(_Galleria alvearia_), which, although quite harmless in its perfect
form, is in its larval state extremely injurious to beehives.
The mother moth contrives, aided by her tiny form and sombre colouring,
to slip past the sentries at the mouth of the hive, and to lay her eggs
among the combs. This done, she dies, but the evil of her visit lives
after her.
Each of the eggs is hatched into a little caterpillar, having a soft
grey body, but a hard, horny head of a black-brown colour. As soon as
they are hatched they begin to feed, eating not only the waxen combs,
but the honey and the bee-bread which were intended for the support of
the legitimate inhabitants.
The reader may ask why the bees do not destroy this marauder on their
premises. They would be only too glad to do so, but they cannot touch
it. As it eats its way along, it constructs a strong silken tube, within
which it lives, and which it gradually lengthens. This tube or gallery
is exceedingly tough, and perfectly capable of resisting the bee’s
sting. Moreover, the caterpillar traverses its tube with such rapidity
that the bee has no chance of knowing whereabouts the caterpillar may be
when it makes its attack. When it feeds it only protrudes its armed
head, the horny covering of which is an effectual protection against the
sting.
When these creatures fairly get hold of a hive, the damage which they do
is terrible, the whole of the combs being enveloped in the
ever-increasing labyrinth of tubes. Even the bees themselves fall
victims to the Galleria-moth, for the silken tunnels are driven through
and through the combs, enveloping the broad cells as in the meshes of a
net. Consequently, when the young bees are developed, they cannot escape
from their cells, and perish miserably.
Nor do these tiresome insects confine themselves to hives; but they have
an extraordinary facility for discovering bee-combs after they are
removed from the hive. Some years ago I was making a collection of
various insect habitations, and had brought together a carefully
selected set of combs, showing the internal structure of the hive, and
the different cells which are inhabited by the worker, the drone, and
the queen bee.
One day, when about to arrange the collection in a glass case, I found
that the whole of the combs had been destroyed by the Wax-moth. Scarcely
a square inch of comb remained, and the contents of the box were little
more than a congeries of Wax-moth galleries. Even the Wasp and Hornet
nests which had been placed in the same box had been attacked, and,
although they had not been so utterly destroyed as the waxen cells, they
had been sufficiently injured to render them unfit for exhibition.
Many other insects work on the same principle. Certain Termites, for
example, construct tunnels of clay, in order to conceal them on their
travels, and have the art, even in the hottest and driest weather, of
mixing their clay with some liquid which renders it, when dry, nearly as
hard as stone. Indeed, there have been instances where the Termites have
attacked the wooden beams of houses, and literally transformed them into
beams of stone.
Then there are many Ants, notably several species of South America,
which cover their approach by tunnels, and never venture into the open
air.
GRAVITY AS A PROPULSIVE AGENT.
The two figures on the accompanying illustration will almost speak for
themselves.
We have already seen how the same force of gravitation which causes the
avalanche to thunder down the precipice may be utilised as a means of
projecting missiles in time of war. When, however, the stones or beams
were once sent on their destructive mission, they were out of the
control of those who launched them. We now come to a modification of the
force of Gravity, by which the missile, if we may so term it, is kept
under control, its power increased or diminished at will, and its point
of attack shifted according to the requirements of the moment.
[Illustration: Ram.]
[Illustration: Head of Battering-Ram.]
Before the invention of artillery, the Battering-ram was by far the most
formidable engine that could be brought against a fortified place. The
principle of the Battering-ram was simple enough. A long and heavy
beam, generally the trunk of a tree, was suspended by ropes at the
centre of gravity, so that it could be swung backwards and forwards.
Although a simple beam was an effective weapon, its value was much
enhanced by loading the thickest end with a heavy mass of metal, usually
iron, and, when there was time for adornment, roughly modelled into the
form of a ram’s head.
Generally the Battering-ram was mounted on an elevated platform, and the
soldiers who worked it protected by a roof, which was called by the name
of Testudo, or Tortoise. The force of this weapon was tremendous, and no
wall, however strong, could resist it. Sometimes the beam was
considerably more than a hundred feet in length, being composed of
several pieces bolted and banded together with iron.
It may easily be imagined that such a weapon as this must have been a
most terrible one, and, indeed, the whole success of the siege
practically depended upon it. The assailants did their best to bring the
Battering-ram into position under the walls, and the besieged did their
best either to keep it away, or to neutralise its effects by catching it
with nooses, dropping large stones upon it so as to break or dismount
it, or, if they could not succeed in either of these attempts, they
deadened the force of its blows as well as they could by interposing
large sacks of wool between the wall and the head of the ram.
Considering the style of architecture which was then used in
fortification, namely, a combination of height with thickness, the force
of the Battering-ram would be even greater than that of artillery. The
regular and rhythmical swing of the ram would soon communicate a
vibratory motion to the wall, which would of itself tend to disintegrate
the whole structure, while the blows of the iron head beneath broke away
the stones, and rendered the downfall of the fort a mere matter of time.
The reader need hardly be reminded that the Battering-ram was so called
because its mode of attack was practically the same as that of the
animal from which it took its title.
MISCELLANEA.
By slow degrees, mankind, as they advance in civilisation, have robbed
warfare of many horrors. Non-combatants, for example, are now left
unharmed. Poisoned weapons have, by common consent, been abolished, and
so have those instruments of warfare which, though they do not simply
poison the blood by means of bodily wounds, do so by means of noxious
vapours poured into the lungs.
It is sometimes rather unfortunate when civilisation and semi-barbarism
meet in battle; the former respecting the customs of honourable warfare,
and the latter ignoring them. For example, in olden times, one of the
most potent weapons in naval combat was the “stink-pot”--_i.e._ a vessel
filled with sulphur and other ingredients, and emitting a smoke which
was death when inhaled. Among the American Indians the well-known
Chili-plant was much used for this purpose, the very first breath that
was taken of the thin and almost invisible smoke causing the throat to
contract as if clutched by a strong hand. If then any enemies had taken
refuge in a cave, or were suspected of having done so, a fire was
lighted at the entrance, a quantity of chilis thrown on it, and the rest
left to time. No being could endure that smoke and live, and they must
either stay in the cave and die, or come out and deliver themselves up
to their foes. The former was the better part to take, as suffocation,
however slow, is only an affair of a few minutes, while death by torture
is prolonged through hours.
[Illustration: Bombardier-Beetle.]
[Illustration: Chinese Stink-Pots.]
In the late Chinese war the stink-pot was extensively used, and our
sailors took it in very bad part that the enemy should be allowed to
employ such weapons, and they should be debarred from using them.
Whether this principle is still retained in the defence of fortresses I
do not know. I recollect, however, some twenty years ago, going over a
fortress in which suffocation was employed as a means of defence. A long
gallery was so placed that the assailants were tolerably sure to force
their way into it, thinking that it led to the interior of the fort.
It was, however, nothing but a trap, for it had no exit. As soon as a
number of the assailants had poured into this trap, their exit was
suddenly cut off by machinery provided for the purpose, and at the same
time a quantity of sulphur and lighted charcoal was shot into the
gallery from above, and the aperture instantly closed. It would be
absolutely impossible that any one who had been enclosed in that
terrible chamber should escape with life, for the first breath of that
deadly vapour would render the strongest man insensible.
* * * * *
NATURE, as usual, has anticipated Art even in this particular.
In several parts of England, and especially along the shores of the
Thames towards Gravesend, a little beetle is to be found under the flat
stones of the river bank. Its scientific name is _Brachinus crepitans_.
When this insect is alarmed, it has the power of ejecting a peculiar
liquid, which, when it comes in contact with the atmosphere, bursts into
a sort of pale blue-green flame, followed by a kind of smoke. Sometimes,
when a tolerably large stone is lifted, the little explosions will go
popping about in a most curious manner. Indeed, they carry reminiscences
of school days, when it was a joy to distribute single grains of coarse
gunpowder on the bars of the grate, and watch them melt, take fire,
explode, and send forth little clouds of smoke. The insect is popularly
called the Bombardier-beetle. Whether or not this capability be given as
a means of defence I cannot say, but it assuredly answers that purpose.
There are several of the voracious Carabidæ, or Ground-beetles, which
would be very glad to make a meal of the Brachinus. When, however, the
Bombardier-beetle finds itself on the point of being overtaken, it
elevates the abdomen with a peculiar gesture, and ejects the liquid. The
effect on the pursuer is remarkable. It seems overwhelmed and stupefied
by the sudden attack, moves about for awhile as if blinded, and, by the
time that it has recovered its sense, the Bombardier-beetle is out of
sight.
In some of the hotter parts of the world there are several species of
Bombardier-beetles which attain considerable size, and their discharge
is powerful enough to discolour the skin of the human hand.
* * * * *
I HAVE felt some little difficulty in classifying the curious invention
which will now be described, but, as it is used for the purpose of
making bullets, I have placed it in the category of War.
[Illustration: SILK APPARATUS OF SILKWORM.]
[Illustration: BULLET-MAKING APPARATUS.]
In the days of “Brown Bess,” as the old musket used to be called,
precision of aim was not required, for no commander dreamt of opening
fire until the enemy were at comparatively close quarters. In those days
the bullets were spherical, and cast in moulds. After a time, when the
Enfield rifle displaced the musket, and did double the execution at
three times its range, bullets were still cast, though their shape was
altered, and they took a sugar-loaf form instead of being spherical.
The rifle-testing machine at Woolwich, however, soon showed that at long
ranges a cast bullet was nearly useless, one part being always lighter
than another, and air-bubbles often taking the place of lead. After
being cast, therefore, the bullets were placed in a “swedge,” or
“swage,” _i.e._ a machine by which the lead was forcibly compressed
until it was of a tolerably uniform density. Even this process, however,
did not insure absolute exactness, and then a machine was invented by
means of which the process of casting was superseded, and the bullets
were pinched or squeezed, so to speak, out of cold lead.
On the right hand of the illustration is a plan of the ingenious
apparatus by which the lead is supplied to the machine which actually
forms the bullets. The sketch is not meant as a drawing of the actual
machine, but is merely intended to show the principle.
The chief parts in this machine are a hollow cylinder, a piston, and a
delivery tube. The cylinder is shown at A, and when used, is filled with
melted lead. The piston, B, is then forced upwards by hydraulic
pressure, driving the lead through the delivery tube. As it issues into
the air it hardens, and thus forms a solid rod of lead, C. This rod is
then passed into the next machine, where it is cut into regular lengths,
and these pieces are then placed in moulds, and forced into form by
enormous pressure. Were it not for this ingenious machinery, the
wonderful scores which are now made at long distances would be
impossible.
* * * * *
NOW let us compare Art with Nature, as seen on the left hand of the
illustration, which is a chart or plan of the spinning apparatus of the
Silkworm.
When I first saw the bullet-making machine at work, I at once perceived
that it was nothing more than a repetition in metal of the beautiful
mechanism which I had so often admired in this insect. In order to show
the close analogies of the two objects, I have marked them with similar
letters.
A represents the upper part of the reservoir or vessel which contains
the silk in a liquid state, B B are the muscles which contract the
reservoir and force the liquid matter out. It will be seen that both
these vessels terminate in a delivery tube, identical in office with
that of the bullet-making machine. As soon as the liquid silk passes
into the air it is hardened, and is formed into a silken rod, C, just as
is the lead in the machine. The only difference between the two, if it
can be called a difference, is, that in the silkworm the rod is double,
whereas in the machine it is single. The principle, however, is
identical in both cases. The webs of spiders, and the threads by which
so many caterpillars suspend themselves, and with which they make their
nests, are all formed on the same design, namely, a reservoir containing
a liquid which is squeezed through a tube, and hardens when it comes in
contact with the air.
ARCHITECTURE.
CHAPTER I.
THE HUT, TROPIC AND POLAR.--PILLARS AND FLOORING.--TUNNEL ENTRANCE
OF THE IGLOO.--DOORS AND HINGES.--SELF-CLOSING TRAP-DOORS.
Primitive Architecture evidently borrowed from the Lower
Animals.--Roof Hut of the Nshiego Mbouvé of Western
Africa.--Platform Hut of the Orang-outan of Borneo.--Lake Dwellers
and their Huts.--Tree-huts of Southern Africa, and their
Uses.--Ascendancy of the Wild Beast over Man.--Snow-hut of the Seal
copied by Esquimaux, and its Value shown.--Pillars and
Flooring.--Crypt and Cathedral.--The Cuttle “Bone” and its
many-pillared Structure.--The Wasp-nest, its Pillars and
Floors.--Tunnel Entrances to Igloo.--Sudden Formation of
Snow.--Nest of the Fairy Martin.--The Sand-wasp and its Mode of
Building.--Doors and Hinges.--Eggs of the Gnat and
Rotifer.--Cocoons of Ichneumon-flies.--Habitations of
Microgaster.--Trap-doors in Nature and Art.--Habitation of the
Trap-door Spider.--A Nest upon a Pillar.
THE HUT.
There can be little doubt that mankind has borrowed from the lower
animals the first idea of a dwelling, and it is equally true, as we
shall presently see, that not only primitive ideas of Architecture are
to be found in Nature, but that many, if not all, modern refinements
have been anticipated.
To begin at the beginning. The first idea of a habitation is evidently a
mere shelter or roof that will keep off rain from the inhabitant. When
Mr. Bowdich was travelling in Western Africa, he was told that the
Njina--another name for the Gorilla--made huts for itself from branches,
the natives also saying that it defended these huts with extemporised
spears. A more truthful account is given of the Mpongwe and Shekiani,
namely, that the animal builds a hut, but lives on the roof, and not
under it.
Although this information has since proved to be false, there was a
foundation of truth in it, for there really is an ape in that part of
Africa which makes huts, or rather roofs, for itself. This animal is the
Nshiego Mbouvé (_Troglodytes calvus_).
This remarkable ape has a curious way of constructing a habitation.
Choosing a horizontal branch at some distance from the ground for its
resting-place, the animal erects above it a roof composed of fresh
branches, each laid over the other in such a way that rain would shoot
off them as it does from a thatched roof. M. du Chaillu gives the
following account of this habitation:--
[Illustration: NEST OF NSHIEGO MBOUVÉ.]
[Illustration: AFRICAN TREE-HUT.]
“As we were not in haste, I bade my men cut down the trees which
contained the nests of these apes. I found them made precisely as I have
before described, and as I have always found them, of long branches and
leaves laid one over the other very carefully and thickly, so as to
render the structure capable of shedding water.
“The branches were fastened to the tree in the middle of the structure
by means of wild vines and creepers, which are so abundant in these
parts. The projecting limb on which the ape perched was about four feet
long.
“There remains no doubt that these nests are made by the animal to
protect it from the nightly rains. When the leaves begin to dry to that
degree that the structure no longer sheds water, the owner builds a new
shelter, and this happens generally once in ten or fifteen days. At this
rate the Nshiego mbouvé is an animal of no little industry.”
The roof which this ape builds is from six to eight feet in diameter,
and is tolerably circular, so that it looks something like a large
umbrella. When the animal is at rest it sits on the branch with one arm
thrown round the stem of the tree, in order to support itself during
sleep. In consequence of this attitude the hair is rubbed away on one
side, thus earning for the ape the specific title of _calvus_, or bald.
* * * * *
IT is rather remarkable that the Orang-outan of Borneo is likewise a
house-builder, though not in the same manner as the African ape which
has just been mentioned. This animal has a way of weaving together the
branches of trees, so as to make a platform on which it can repose, its
enormously powerful arms being of great service in this task. The animal
seems to make its platform in quite a mechanical manner, and it has been
noticed that when an Orang-outan has been mortally wounded, it has
expended its last energies in twisting the branches together so as to
form a couch on which it can lie down and die.
* * * * *
PUTTING aside those cases where huts have been erected in trees by way
of amusement, we may find instances where human beings have been forced
to make their habitations in trees.
In some places, such as certain parts of South America, the natives are
forced to make their houses in trees, partly on account of the climate,
and partly for the purpose of avoiding the mosquitoes.
The delta of the Orinoco River is nearly half as large as England, and
for a considerable part of the year is deep in water. Yet this tract is
inhabited by the Warau tribe, who find in it their only mode of escape
from the tiny but terrible mosquito. We in England know but little of
the miseries inflicted by these insects, which are so plentiful in some
parts of America that they are gathered in bags, pressed into thick
cakes about as large as ordinary dinner-plates, and an inch in
thickness, and then cooked and eaten.
Now it is found that although the mosquito infests the banks of rivers,
it cannot venture far from land. The Waraus, therefore, make for
themselves habitations which are far enough from land to baffle the
mosquitoes, and near enough to be easily reached in canoes.
Fortunately for them, there is a tree called the Ita Palm, belonging to
the genus Mauritia, which loves moisture, and grows abundantly in this
delta. The Waraus, therefore, make their habitations in these trees,
connecting several of them together with cross-beams, and laying planks
upon them so as to form the flooring of their simple huts. Here they
maintain themselves chiefly by fishing, but are sometimes obliged to
visit the mainland, in spite of the mosquitoes. When, however, they
return, they halt at some distance from the shore, and with green boughs
carefully beat out every mosquito from the canoe before they dare to
approach their dwellings.
The once-celebrated Lake Dwellers of Switzerland evidently lived after a
similar fashion.
* * * * *
IN this case insects drive human beings into trees, but there are
instances where nobler animals have produced the same effect.
Some years ago there lived in Southern Africa a powerful chief called
Moselekatze, who spent his whole life in warfare, converting all the
male inhabitants into soldiers, dividing them into regiments, ruling
them with the extreme of discipline, and by their aid devastating the
neighbouring countries. He swept off all the cattle, which constitutes
the wealth of the Kafir tribes, and either killed the male inhabitants
or pressed them into his service.
The land was in consequence deprived of its natural defenders, and the
wild beasts, especially the lions, increased rapidly, so that the
position of the survivors was a really terrible one. They had no cattle
to furnish the milk which is the chief food of the Kafir tribes; their
weapons had been taken by Moselekatze; and they were forced to live
almost entirely on locusts and wild plants. By degrees the lions became
so numerous and daring, that the slight Kafir huts were an insufficient
protection during the night, and the disarmed and half-starved
inhabitants were perforce obliged to make their habitations in trees.
Dr. Moffat, the well-known missionary, saw one tree in which there were
no less than twenty huts. They were conical, and made of sticks and
grass, the base resting upon a platform or scaffold laid upon the fork
of a horizontal branch. The only mode of approach to these huts was by
notches cut in the trunk of the tree.
How needful were these precautions was shown by the fact that the
missionary himself spent a night in one of these aërial huts, and had
the pleasure of hearing a number of lions snarl and growl all night over
a rhinoceros hump which he had placed in an oven made of a deserted
ant-hill. The oven, however, was too hot for the lions, and they had to
retreat at daylight.
* * * * *
PASSING from the tropics to the polar regions, we now take an instance
where man has acknowledgedly copied an animal in the construction of his
dwelling.
In Esquimaux-land, where no trees can grow, where for months together
the sun never rises above the horizon, where the temperature is many
degrees below zero, and where the land and ice are alike covered with a
mantle of snow so thick that every landmark is abolished, it would seem
that no human beings could support life for one week. There is neither
timber for house-building nor wood for fuel, so that shelter, warmth,
and cookery seem to be equally impossible, and as these are among the
prime necessities of human life, it is not easy to see how mankind could
exist.
[Illustration: SNOW-HOUSE OF SEAL IN ESQUIMAUX-LAND.]
[Illustration: SNOW-HOUSE OF ESQUIMAUX.]
Yet these very regions are inhabited by sundry animals, and it is by
copying them that Man can keep his place. We have already seen how the
Esquimaux hunter copies the Polar Bear, and we have now to see how he
copies the Seal in the material and form of his dwelling-house, and not
only contrives to live, but to enjoy life all the more for the singular
conditions in which he is placed. Captain Hall mentions, in his “Life
with the Esquimaux,” that one of the natives, named Kudlago, who was
returning to his native country after visiting the United States, died
while on board the ship. Towards the end of his life he was yearning for
ice, and his last intelligible words were, “Do you see ice? Do you see
ice?”
On the vast plains of ice that are formed in the winter-time the snow
lies thickly, and yet upon such an inhospitable spot the mother seal has
to make a home for her tender young. This she does in the following
manner:--
She has already preserved a “breathing hole” in the ice, through which
she can inhale air. How she finds so small a hole under the surface of
the ice, where there are no landmarks to guide her, is a marvel to every
swimmer. She has to chase fish and follow them in all their winding
courses, and yet, when she is in want of air, is able to go straight to
her breathing hole, and there take in a fresh supply of oxygen.
When she is about to become a mother, she enlarges this breathing hole
so as to make it into a perpendicular tunnel. She then, with the sharp
nails of her fore-paws, or flippers, scoops away the snow in a dome-like
form, as shown in the illustration, taking the snow down with her
through the ice, and allowing it to be carried away by the water. By
degrees she makes a tolerably large excavation of a hemispherical shape,
and when her young is born she deposits it on the ice-ledge around the
tunnel. From ordinary foes the young Seal is safe, and nothing can
discover the position of the house unless guided by the sense of smell.
How the Polar Bear and the Esquimaux hunter discover the dwelling and
capture the inmates we have already described in the chapter treating of
War and Hunting. Our present business is with the dwelling itself.
Comparatively few of these snow-houses, or _igloos_, as they are called,
are discovered, and they remain intact until the summer sun melts the
roof and exposes the habitation. By this time, however, the young Seal
has grown sufficiently to shift for itself, and no longer needs the
shelter of a dwelling.
* * * * *
THE winter hut, or igloo, of the Esquimaux is made of exactly the same
shape and of similar materials to the dwelling of the Seal, the chief
difference being that it is built instead of excavated.
In order to save time, the igloo is generally erected by two men, one of
whom supplies the material, and the other acts as bricklayer and
architect in one. Each begins by tracing a suitably sized circle in the
snow, which he clears away to some depth, so as to preserve a firm
surface, either as a floor or as the material for the wall. In this work
both men are equally valuable, for the skill required to cut the slabs
of snow into such a shape that they can be formed into a hemispherical
dome is quite as much as that which is needed for putting them together.
I will call them the cutter and the builder. Sometimes a young hand is
employed by way of labourer, and passes the snow slabs to the builder as
fast as they are cut.
The builder receives the slabs, and arranges them in regular order,
always taking care to “break the joints,” just as do our bricklayers of
the present day. Always remaining within the circle, he gradually builds
himself in, and when he has quite finished the house, he cuts a hole
through the side, emerges, and, by the help of his partner, puts on the
finishing touches. He usually also adds a sort of tunnel to the door,
through which any one must creep on his hands and knees if he wishes to
enter the igloo. This part of Esquimaux architecture will presently be
noticed more in full.
Perhaps the reader may wish to know what provision there is for
ventilation. The answer is simple enough. There is none, the Esquimaux
not requiring ventilation any more than they require washing. The two,
indeed, generally go together; and it may be observed, even in our own
country, that those who object to fresh air, and are always complaining
of draughts, have a very practical aversion to the use of fresh water,
and but little confidence in what Thackeray calls the “flimsy artifices
of the bath.”
The Esquimaux never washes, and knows not the use of linen.
Consequently, it is no matter of surprise that a sailor of Captain
Hall’s crew could not make up his mind to enter an igloo. “Whew!”
exclaimed the man, “by thunder, I’m not going in _there_! It’s crowded,
and smells horribly. How it looms up!”
Considering that there were inside that igloo a dozen Esquimaux, all
feasting on a raw, newly killed, and yet warm seal, the sailor had
reason enough to decline a visit. Captain Hall, however, determined, in
his character of explorer, to brave the strange odours, and moreover to
join the inmates in their feast, knowing that as he would have to live
among the Esquimaux for some two years, he would be forced to live as
they did, and might as well begin at once. Consequently on this resolve,
he drank the still steaming blood, and quaffed it from a cup which an
Esquimaux woman had just licked clean.
FLOORS AND PILLARS.
One decided step in Architecture is the invention of the Pillar, and its
capabilities of aiding to sustain another floor above it. We see this
principle carried out in our great cathedrals, where the use of the
Pillar is almost infinite. Take, for example, Canterbury Cathedral. A
heedless visitor might easily pass through the nave, enter the choir,
visit the various side-chapels, and “Becket’s Crown,” without thinking
that under his feet is a vast chamber, and that the floor on which he
stands is, in fact, the roof of a great crypt.
[Illustration: WASP-COMBS.]
[Illustration: SLAVE SHIP.]
The weight of the Cathedral, with its lofty towers, is so tremendous,
that the building could not be erected simply upon the ground, but rests
upon a complicated substratum of pillars and arches, whereby the weight
is spread over a large surface. In fact, the Cathedral is really two
buildings, the one erected upon the other.
* * * * *
IN Nature there are many instances of pillars supporting different
floors. One of the most beautiful examples is to be seen in the common
Cuttle-bone, as it is called, this being the internal skeleton, if it
may be so termed, of the common Sepia (_Sepia officinalis_), which is so
often found on our coasts, especially after a gale. This year (1875) I
found eight of these Cuttle-bones on the Margate sands, and all within a
space of some twelve feet square.
This so-called bone is really composed of the purest chalk, for which
reason it is in great request as a dentifrice, being easily scraped to
almost impalpable powder when wanted, and not liable to be spilled, as
is the case with any ordinary tooth-powder.
It is exceedingly light--so light, indeed, that it floats like a cork,
even in fresh water. Now, as chalk is very much heavier than water, we
may naturally ask ourselves how this lightness is obtained. If the upper
surface be examined, it will be seen to be traversed by a vast number of
wavy lines, something like the markings of “watered” silk. These show
the lines of demarcation between the multitudinous rows of pillars of
which the whole structure is formed.
If the “bone” be sharply snapped in the middle, and the particles of
white dust blown away, a wonderful structure presents itself, which can
be partially discerned by the naked eye, though a microscope is required
to bring out its full beauties.
Even with an ordinary pocket lens we can make out some of its wonders.
The object looks like a vast collection of basaltic columns, except that
the pillars are white instead of black, and they are arranged in rows
with the most perfect accuracy, just as if the place of each had been
laid down with rule and compass. They are scarcely thicker than ordinary
hairs, but they are beautifully perfect, and rise in tier after tier as
if they were parts of a many-storied building. As a definite space
exists between the pillars, the reader will understand why the whole
structure should be so much lighter than water. In order, however, to
see these wonderful pillars in perfection, a very thin section should be
taken, and viewed with polarised light.
* * * * *
ANOTHER excellent example of Pillars and Flooring is to be found in the
nests of various Wasps, including that of the Hornet.
In these nests the combs are arranged horizontally, and not vertically,
like those of the bees, and in consequence they have to be supported in
some way. This object is achieved by means of multitudinous pillars made
of the same papier-mâché of which the combs are formed, and attached to
the successive rows of combs. There is, however, one curious point of
difference between the Wasp-comb and human architecture, namely, that
the pillars do not support floors, or rest upon them, but sustain the
weight of those which hang from them. The mouths of the cells are all
downwards, and the combs are therefore suspended from the pillars,
instead of being supported by them.
TUNNEL ENTRANCE TO THE DWELLING.
We have already found occasion to treat of the snow-house, or igloo, of
the Esquimaux, and have now to speak of a subsidiary, though necessary,
part of Esquimaux architecture.
Perhaps the reader may have been unfortunate enough to travel by rail in
the depth of winter, and to be associated with fellow-passengers who
will insist on closing every window, even though the carriage be
crowded. Suppose that on such a day, the weather being perfectly fine,
the train stops at a station, and the guard outside opens the door to
see if another passenger can be accommodated with a place.
No sooner is the door opened than a shower of snow at once fills the
carriage. This is simply the moisture suspended in the air and generated
by human lungs. The rush of cold air at once freezes this moisture and
converts it into snow, thus showing those who will condescend to learn,
that they have been breathing and re-breathing the air that has passed
through a variety of human lungs, and is charged with their different
moistures. I have seen the same phenomenon at a dinner party, where,
after the withdrawal of the ladies, one of the windows was opened.
Now, in Esquimaux-land, it is absolutely necessary to conserve every
atom of heat, for the cold is so intense that if a cask of water be near
a coal fire, only the part next the fire will be thawed, the rest being
ice. Cold, therefore, is a foe which has to be fought and kept away from
the household. Then there are other foes--such as Polar Bears, for
instance--which would be only too glad to get into an igloo and make a
meal of its inhabitants. The Esquimaux architect, therefore, avails
himself of an ingenious device by which he can set both foes at
defiance.
In summer-time he contents himself with a hut made of skins, and merely
hangs a skin over the entrance by way of a door. But in the winter, when
he is driven to his snow-house for shelter, he acts in a very different
manner. Instead of merely cutting an aperture for a door in the side of
the igloo, he constructs a long, low, arched tunnel, so small that no
one can enter the igloo except by traversing this tunnel on his hands
and knees. Sometimes a number of huts are connected with each other, one
or two tunnels leading into the air, and the rest serving merely as
passages from one hut to the other.
[Illustration: NESTS OF FAIRY MARTIN. TOWERS OF SAND-WASP.]
[Illustration: HUTS OF ESQUIMAUX.]
* * * * *
IN Nature are several examples of tunnels constructed on the same
principle.
There are, for instance, the curious nests of the Fairy Martin of
Southern Australia (_Hirundo Ariel_), which bear a singular resemblance
to oil-flasks, the body of the nest being rather globular, and the only
entrance being through a tolerably long, tunnel-like neck.
Then there are the various Weaver-birds of Africa, with their
long-necked nests. Some of these strange edifices look almost like
horse-pistols suspended by the butt, so round is the nest, and so long
and narrow is the tunnel-like entrance.
* * * * *
PASSING to the insect world, we find the same principle carried out by
the now familiar Mason-wasp (_Odynerus murarius_), some of whose nests
are represented in the illustration.
This insect makes a burrow, and at the bottom of it deposits an egg,
together with a number of little caterpillars on which the grub, when
hatched, will feed. The mother Wasp is not allowed to pursue this task
without taking precautions against the admission of enemies to her
burrow, especially the ichneumon-flies. As may be inferred from its
popular name, the Sand-wasp always selects a sandy spot for its burrow,
and generally chooses a piece of tolerably hard sandstone, which it is
able to bite into little pellets, aided by a kind of liquid which it
secretes.
The following account of the manner in which the Mason-wasp forms and
defends its home is taken from the invaluable “Insect Architecture,” by
Rennie.
The author begins by describing the form and depth of the burrow, and
the soil in which it is made. He then proceeds to show the wonderful
manner in which the mother Wasp purveys food for the use of her future
young whom she will never see. Guided by instinct, she places in the
burrow exactly the number of caterpillars which the young Mason-wasp
will have to consume before it attains its perfect condition. It is
believed that she partially paralyzes them with her sting before placing
them in the burrow. At all events, when they are once packed away, they
never move, so that the tiny Wasp grub can feed upon them quite at its
leisure.
Here is Rennie’s account of the Sand-wasp and her burrow-making:--
“When this wasp has detached a few grains of the moistened sand, it
kneads them together into a pellet about the size of one of the seeds of
a gooseberry.
“With the first pellet which it detaches, it lays the foundation of a
round tower, as an outwork, immediately over the mouth of its nest.
Every pellet which it afterwards carries off from the interior is added
to the wall of this outer round tower, which advances in height as the
hole in the sand increases in depth. Every two or three minutes,
however, during these operations, it takes a short excursion, for the
purpose probably of replenishing its store of fluid wherewith to moisten
the sand. Yet so little time is lost, that Réaumur has seen a mason-wasp
dig in an hour a hole the length of its body, and at the same time build
as much of its round tower.
“For the greater part of its height this round tower is perpendicular,
but towards the summit it bends into a curve, corresponding to the bend
of the insect’s body, which, in all cases of insect architecture, is the
model followed. The pellets which form the walls of the tower are not
very nicely joined, and numerous vacuities are left between them, giving
it the appearance of filigree-work.
“That it should be thus slightly built is not surprising, for it is
intended as a temporary structure for protecting the insect while it is
excavating its hole, and as a pile of materials, well arranged and ready
at hand, for the completion of the interior building,--in the same way
that workmen make a regular pile of bricks near the spot where they are
going to build. This seems, in fact, to be the main design of the tower,
which is taken down as expeditiously as it has been reared.
“Réaumur thinks, that by piling in the sand which has previously been
dug out, the wasp intends to guard its progeny for a time from being
exposed to the too violent heat of the sun; and he has sometimes even
seen that there were not sufficient materials in the tower, in which
case the wasp had recourse to the rubbish she had thrown out after the
tower was completed. By raising a tower of the materials which she
excavates, the wasp produces the same shelter from external heat as a
human being would who chose to inhabit a deep cellar of a high house.
“She further protects her progeny from the ichneumon-fly, as the
engineer constructs an outwork to render more difficult the approach of
an enemy to the citadel. Réaumur has seen this indefatigable enemy of
the wasp peep into the mouth of the tower, and then retreat, apparently
frightened at the depth of the cell which she was anxious to invade.”
It is no wonder that the Sand-wasp should be so anxious to insure the
safety of her nest, for her foes are multitudinous. Putting aside the
ordinary Ichneumon-flies, we have the predatory Tachinæ, which are
always hovering over such nests, and trying to deposit eggs therein. For
many years I have been in the habit of receiving letters from novices in
entomology, wanting to know whether I am aware that the common Housefly
is in the habit of acting as a parasite. Of course, the writer has
mistaken the Tachina for a house-fly, but I cannot regret the fact that
some one has really begun to observe Nature, and not only to read books.
DOORS AND HINGES.
Having seen that both in Nature and Art the entrances to dwellings are
guarded by tunnel-like approaches, we come naturally to another mode of
guarding the entrance, namely, by a door moving on hinges. As to the
multitudinous examples of doors and hinges in modern civilisation, we
need hardly discuss them, except to show the exact analogies which occur
in Art and Nature.
Doors moving on hinges are very plentiful in Nature, even where we
should least expect them. Take, for example, an egg, especially the egg
of an insect, and we shall see that it is just about the last object in
which we should expect to find a hinged door. Yet, if the reader will
refer to the illustration on page 7, he will see that the tiny eggs of
the common Gnat, numerous as they may be, are each furnished with a door
which opens as soon as the inmate is hatched, and allows the little
larva to escape into the water.
Another still more remarkable instance of a hinged door in an egg is to
be found in one of the Rotifers, or Wheel-Animalcules, so called because
they possess an apparatus of movable cilia, which, when set in motion,
looks exactly like a wheel running round and round. As the full-grown
creature is barely one thirty-sixth of an inch in total length, the
structure of its eggs must be infinitesimally beyond the range of human
vision.
Yet, just as the telescope sets at partial defiance the vast spaces that
intervene between our earth and her sister planets, so the microscope
performs a similar task in the infinitesimally minute. And, under the
all-revealing lens of the microscope, the little egg of the Brachionus,
though absolutely invisible to the unaided eye, yields up its secrets.
Fortunately, the shell is so transparent that the interior of the egg
can be seen through it as if it were a mere film of glass. The
astonishing division and re-division of the yolk take place before our
eyes, being divided first into two, then into four, then into eight,
then into sixteen, then into thirty-two, and so on, until the whole mass
of the yolk is cloven into divisions too numerous to count.
By degrees, the form of the young Brachionus is developed within the
egg, even to the very teeth, which work away as persistently as if large
stores of food were being passed through them.
When the young is ready to take its place in the world, a new
development occurs, which has been well related by Mr. Gosse:--
“All these phenomena have appeared in the egg we are now watching; and
at this moment you see the crystalline little prisoner, writhing and
turning impatiently within its prison, striving to burst forth into
liberty.
“Now, a crack, like a line of light, shoots round one end of the egg,
and in an instant, the anterior third of the egg is forced off, and the
wheels of the infant Brachionus are seen rotating as perfectly as if the
little creature had had a year’s practice.
“Away it glides, the very image of its mother, and swims to some
distance before it casts anchor, beginning an independent life. At the
moment of escape of the young, the pushed-off lid of the egg resumes its
place, and the egg appears nearly whole again, but empty and perfectly
hyaline (_i.e._ all but transparent), with no evidence of its fracture,
except a slight interruption of its outline, and a very faint line
running across it.”
To pass from the egg to a more advanced stage in life. All practical
entomologists have been greatly annoyed, in their earlier years of
collecting, to lose larva after larva, from the attacks of
Ichneumon-flies. It _is_ certainly rather beyond the limits of ordinary
patience to discover, watch over, and secure successfully a rare
caterpillar, and then to find that it has been “stung” by an
Ichneumon-fly.
The veteran entomologist, however, troubles himself very little about
such minor misfortunes, and, as a rule, more than compensates for them
by preserving the intrusive Ichneumon-fly, and giving in his diary full
details of the insect on which it was parasitic, of the plant on which
the caterpillar lived, the date of its appearance, and its numbers.
Now, there are many of these parasitic insects, notably those belonging
to the genus Microgaster, which invariably make doors in their cocoons.
I have now before me groups of cocoons made of the two commonest British
species, namely, _Microgaster glomeratus_ and _Microgaster alvearius_,
and in both of them each tiny cocoon is furnished with a hemispherical,
hinged door. I have also some exquisitely beautiful groups of
Microgaster cocoons found in the West Indies. They are the purest white,
shine with a satiny lustre, and are arranged round a hollow centre, much
as if they had been gummed to the outside of a very large thimble. There
are many hundreds of them, and every one has its little door still open
as it was when the fully developed insect first made its escape.
* * * * *
ANOTHER curious example of a natural door may be seen by those who will
look for it.
On plants infested with aphides, or “green blight,” as the gardeners
quaintly term them, may often be seen dead aphides much larger than the
rest, globular, brown, and shining. These aphides have been “stung,” as
it is called, by a little Ichneumon-fly belonging to the genus Ophion,
and having, like all its congeners, a flat and sickle-shaped abdomen.
The egg which has been laid in the aphis soon hatches, and the young
Ophion absorbs into itself all the juices of the aphis. It remains
within the body of its involuntary host until it is fully developed,
when it cuts a tiny, but beautifully perfect circular door in the skin,
and emerges, leaving the door open and still attached by its little
hinge.
Considering the small size of the aphis, and that the diameter of the
door is only one-eighth of the length of the insect, the perfection of
its form is really remarkable.
* * * * *
ONE of the achievements of modern Architecture is the Self-closing Door,
especially where it must of necessity close by its own weight, and when
the fitting is so exact, that even the most experienced eye can
scarcely detect it. Such a door is to be found guarding the nest of the
Trap-door Spiders, several species of which are found scattered over all
the warm parts of the earth. A side view of one of these extraordinary
nests is given in the accompanying illustration, and on the other side
is the common trap-door of our cellars.
[Illustration: DOOR OF TRAP-DOOR SPIDER.]
[Illustration: TRAP-DOOR OF COAL-CELLAR.]
The Spiders which make these extraordinary dwellings generally begin by
excavating a nearly perpendicular tunnel in the ground. They line it
with a silken web, and construct a door which exactly fits the orifice,
and which is bevelled so that it shall not sink too far, and thus betray
itself. I have seen and handled one, where the burrow had been sunk
among lichens and mosses, and the trap-door of the nest had been most
ingeniously covered with the same growths. Although the surface of the
slab of earth in which the nest was made is only a few inches square, it
is almost impossible to detect the entrance, so admirably do the mosses
on the door correspond with those outside it.
Almost invariably the nest is sunk in the ground, but I have a specimen
sent to me from India, in which the Spider must absolutely have carried
the clay to a fluted pillar, burrowed in it, and then made its beautiful
habitation. The nest and its inhabitant were sent to me by an officer in
the 108th Regiment, accompanied by the following letter:--
“The packet contains a large Spider and the upper portion of its
peculiar nest, the history of which is as follows.
“On the thirtieth of last month (September, 1870), while searching for
caterpillars on a bush growing close to one of the pillars of my
verandah, which is a very low one, reaching to within a foot of the
ground, I saw in part of the chunam masonry at the foot of the pillar
what I at first sight took to be a couple of seeds sticking to a stone.
On trying to pull one off, I found that it came up with ease, bringing
with it what I thought was the stone.
“But I had scarcely got it up when it was smartly pulled back. This
excited my curiosity, and I raised it again with a little force. I now
saw, to my wonder and admiration, that what I had fancied was a stone
was a small circular door with a pretty broad hinge, made all of silk;
and then distinctly observed a large black spider dart down the hole to
which the above door gave an entrance. But, not knowing the depth, I
broke it.
“This piece I send to you, together with its original owner, who, at the
beginning of my digging operations, ran up suddenly, shut the door in my
face, and hung on to it like grim death when I tried to reopen it. He
soon came away with the upper piece, still keeping the door resolutely
closed.”
ARCHITECTURE.
CHAPTER II.
WALLS, DOUBLE AND SINGLE.--PORCHES, EAVES, AND WINDOWS.--THATCH,
SLATES, AND TILES.
The Wall and its Materials.--Bricks as they are and might
be.--Trade Unionism.--Double Walls and their Uses.--Double
Clothing.--The Refrigerator.--Cooking Vessels.--Fire-proof
Safes.--Cocoon of the Silkworm, and its treble Walls.--Nest of the
Little Ermine, Processionary, Gold-tailed, and Brown-tailed
Moths.--Mud Walls.--Nests of the Termite.--Porches, Eaves, and
Windows.--Nests of the Myrapetra and an Indian Ant.--The Sociable
Weaver-bird and its Nest.--Thatching.--Arms of the
Orang-outan.--Japanese and Chinese Rain-cloaks.--Eggs of the
Gold-tailed Moth.--Action of Fur.--Slates and Tiles.--Scales of
Butterfly’s Wing.--Shell of Tortoise.--Scales of Manis, Fish, and
Armadillo.
We now come to the Walls of the house, in which there is more variety
than might be imagined.
Take, for example, our modern houses of the “villa” type. They are
nothing but the merest shells, made of the flimsiest imaginable
materials. Some years ago, while walking through a suburb where some
very showy houses were being built, I amused myself by going over them
and testing them. There was scarcely a room in which I could not thrust
an ordinary walking-stick through the wall. When they were “finished”
and “pointed,” the houses looked beautiful, but their heat in summer,
cold in winter, and moisture in wet weather, can easily be imagined,
especially as the sand with which the mortar was mixed had been procured
from the banks of a tidal river.
There is not the least necessity for such buildings. It is absurd to run
up such edifices as that, and then charge £120 per annum for rent. The
whole system is as rotten as the houses, and there is nothing but
prejudice and trade-unionism to prevent our houses being cool in summer,
warm in winter, and dry in all weathers.
It is well known that air is practically a non-conductor of heat, and
that therefore a layer of air between two very slight walls is just as
warm as if the wall had been made of solid stone. Now, there are several
inventions whereby the present brick could be made half its present
weight, twice its present strength, hard and smooth as earthenware, so
that it could not absorb water like our common brick, and pierced with
holes through which air could pass.
[Illustration: FUR.]
[Illustration: NEST OF LITTLE ERMINE-MOTH.]
[Illustration: ICE-HOUSE.]
Unfortunately, however, there is a stringent rule among brickmakers and
bricklayers that they are to play into each other’s hands, and that no
bricklayer is to touch a brick which has not been made in some definite
district. Should he do so, he is a marked man, and will stand but little
chance of getting even a day’s work.
The power of the double wall may be seen in many ways. For example, in
the old days of coaching, when one had to pass hour after hour on the
roof of the coach, it was known by practical experience that double body
linen, and two pairs of stockings, worn one over the other, formed the
best preparation for the journey. The reason was, that air became
entangled between the layers of fabric, and acted as a non-conductor of
heat.
Another mode of utilising the principle of the double wall is seen in
the refrigerators which add so much to the comfort of the household in a
hot summer. The one principle of these refrigerators is, to keep a layer
of air between the ice and the surrounding atmosphere. The same
principle may be used in a reverse way, and heat be preserved instead of
repelled. Those cooking-pots are now well known, where half-cooked meat
can be inserted in the morning, and at luncheon-time be turned out quite
hot and perfectly cooked. The fact is, that the vessels in question are
covered with a very thick layer of felt. The felt, however, is only a
device for entangling air, and a double wall would answer the purpose as
well, if not better.
The now well-known fire-resisting safes are made on this principle, and
after they have been for hours in a raging fire, and the outer case has
become red-hot, the interior is quite safe, the papers uninjured, and
even a watch continuing to go.
Then there is the ordinary Ice-house, a sketch of which is given in the
illustration. A pit is first dug in the ground, and thickly lined with
dry branches, straw, &c. The roof is constructed in the same manner,
only the non-conducting power is increased by a thick coating of earth
over the sticks and straw. The door, which is approached by a shelving
cutting, is similarly protected, the covering only being removed when
the door is opened.
I once made a very effective refrigerator out of two hampers, putting a
small hamper inside a large one, and packing the space between them with
straw.
* * * * *
IN Nature we find many examples of this principle, which enables the
inhabitants to bid defiance to frost.
A familiar example may be found in the cocoon of the common Silk-worm
(_Bombyx mori_), and indeed in that of almost any silk-producing insect.
When the caterpillar is about to make its cocoon, it begins by a number
of rather strong threads attached to different points, and making a sort
of scaffolding, so to speak, for the cocoon itself. Upon these is spun a
slight outer cocoon of very loose and vague texture--the “floss silk” of
commerce, and within that is the cocoon proper, in which the insect lies
enclosed. It will be seen, therefore, that there are really three
cocoons, one within the other, namely, the scaffold cocoon, the floss
cocoon, and the silk cocoon itself, so that the inmate is protected from
variations of temperature.
The cocoon of the emperor-moth, which has already been described, is
made on the same principle.
There are several caterpillars which are social in their early stages,
and which construct a common habitation. The Little Ermine-moth.
(Hyponomeuta padella) affords a familiar example of this structure. The
caterpillars are great roamers in search of food by day, and travel from
branch to branch on their strong silken threads. At night, however, they
return to a large white silken habitation which they have spun, and
which they divide into many compartments, as may easily be seen by
cutting the nest open with very sharp scissors. Within this habitation
the caterpillars spin their separate cocoons, so that the system of
double walls is thoroughly carried out.
There is another insect, very common on the Continent, but, happily for
us, not introduced into England. It is called the Processionary Moth,
from its curious habit of marching in exact lines, the head of the
second caterpillar touching the tail of the first, and so on. These
insects have likewise a common home, and spin their own separate cocoons
within it.
* * * * *
[Illustration: NEST OF PROCESSIONARY MOTH.]
[Illustration: COCOON OF SILK-WORM.]
[Illustration: FIREPROOF SAFE.]
There are two other sociable British Moths which make nests on a similar
principle. These are the Gold-tailed Moth (_Porthesia chrysorrhœa_)
and the Brown-tailed Moth (_Porthesia auriflua_). They are both
beautifully white insects, but may easily be distinguished from each
other, the Gold-tailed Moth having some brown-black spots on the upper
wings, and a tuft of golden-yellow hairs at the end of the body; while
the Brown-tailed Moth is without spots, and the tail-tuft is brown.
In habits they are very similar, and the description of the nest made by
one will answer for that made by the other. I believe that broods of
these two species have been known to construct a common nest. The nest
is extremely variable in form, because it depends much on the number of
twigs which it includes. Interiorly, it is divided into a considerable
number of chambers, each containing one or several individuals.
As the caterpillars are hatched late in summer, they have to undergo the
frosts of winter before they can attain their perfect state.
Accordingly, before the winter-time comes on, they strengthen both the
external walls and internal partitions of their nest, and then wait
until the spring brings forth the leafage of the new year.
The nest is a beautiful structure, and I strongly recommend the reader
to look for one in a hedgerow, take it home, and cut it up carefully. I
would, however, advise him, if, like myself, he be subjected to a very
sensitive skin, to be cautious in his handling of the nest. The hairs
with which the pretty black, red, and white caterpillars are studded are
irritant in the extreme.
I have several times suffered from them, and would much rather be
severely stung by nettles than undergo the fierce irritation, mixed with
dull heavy pain, which always accompanies the presence of these hairs.
With me, as I suppose would be the case with persons of similar
organization, these hairs cause large, hard tubercles to rise, just as
if potatoes had been placed under the skin. The hairs of the
Processionary Caterpillar have a similar effect, and in France the
authorities have several times been obliged to close the public gardens
for months, so severe was the pain which the caterpillars inflicted on
persons who passed through the spots infested by them.
MUD WALLS.
There is a mode of wall-building which is much in vogue in some parts of
England, and has much to commend itself. This is the Mud or Concrete
Wall.
At first sight, the very name of a mud house gives an idea of poverty
and misery, and is apt to be connected with hovels and pigsties. Mud
walls, however, if properly built, are far warmer and drier than those
of brick, and are even preferred to those of stone, when the latter can
be easily and cheaply obtained. In Devonshire, for example, where even
the cattle-sheds, or “linhays” (pronounced _linny_), and the pigsties
are made of the rich red stone of the county, it is a common thing to
see village houses built of mud. Sometimes the houses are built of stone
to the height of some ten or twelve feet, and the upper parts made of
mud.
[Illustration: NEST OF TERMITE.]
[Illustration: MUD WALL.]
If the builders are in any way fastidious, they make their walls of a
uniform surface by placing two rows of planks on their edges at a
distance from each other proportionate to the thickness of the wall,
pouring the mud between them, and, when it has sufficiently hardened,
shifting the planks. This, however, is not necessary, and detracts much
from the picturesque look of a genuine mud wall, especially when it is
of that rich red which characterizes the Devonshire soil. These mud
walls are locally known by the name of Cob.
* * * * *
WE have not to go very far in Nature to find good examples of the
strength which can be attained by mud walls.
In all parts of the world where Termites, popularly but wrongly called
White Ants, are to be found, the strength and endurance of the mud wall
can easily be tested. Of gigantic dimensions when compared with the size
of the architect, they not only endure the rain-torrents which wash over
them, but can sustain the weight of the wild cattle, which are in the
habit of using them as watch-towers, and this although they are hollow,
and filled with chambers and galleries.
In Southern Africa these nests are much utilised. There is an animal
called by the Dutch settlers the Aard-vark, which feeds almost wholly
on Termites. At night it issues from its burrow, and, being armed with
large and powerful claws, tears a great hole in the side, and devours
the inmates.
These deserted nests are sometimes used as ovens, as we have already
seen, a fire having been kindled within them for some time, the meat,
well enveloped in leaves, being thrust into them, and the opening closed
with clay. Sometimes they are used as graves, the corpse being placed in
them, and the hollow filled up with earth, while the wall of the Termite
nest, when pounded and mixed with water, is found to be the most
tenacious clay that can be used for building or flooring huts.
PORCHES, EAVES, AND WINDOWS.
We now come to some of the appendages of a house, namely, the Porch by
which the rain is kept from a doorway, the Eaves by which it is kept
from the walls, and the Windows which will admit light and air, but will
prevent the entrance of intruders.
We first take the Porch, two examples of which are shown in the
accompanying illustration, one being the work of human hands, and the
other that of an insect.
The figure on the right hand represents an old-fashioned Porch, such as
is often to be seen attached to old village churches, and which, being
furnished with seats, serves also as a resting-place for those who are
weary.
[Illustration: NESTS OF MYRAPETRA, WITH PORCHES.]
[Illustration: PORCH.]
The figure on the left hand of the illustration is a wonderful example
of the Porch, as constructed by insects. It is the nest of a
honey-making Brazilian wasp named _Myrapetra scutellaris_. The
peculiarity of this nest consists in its exterior being covered with a
vast number of projections made of the same material as the walls of the
nest, but more solid and much harder. The colour of the nest is blackish
brown.
The object of all these projections has not been ascertained, but there
is no difficulty as regards some of them. Without a very careful
examination, it is exceedingly difficult to see any opening by which the
inhabitants of the nest can go in and out. It will be found, however,
that there are many entrances, which are set in a row round the nest,
each opening being situated under a projection, which thus performs the
office of a porch as well as that of concealment.
Another hymenopterous insect carries out the principle of the Porch in
its nest. This is the _Myrmica Kirbyi_, a tiny reddish Ant which
inhabits India. It makes its nest of cow-dung, which it works up into a
texture very like that of an ordinary wasp-nest. A series of large
flakes of this substance overhang the entrances, so that the inhabitants
can enter freely, while rain is kept out. For the purpose of greater
security, one very large flake covers the roof in umbrella fashion. The
whole nest is globular, and about eight inches in diameter.
* * * * *
NEXT we come to the projecting Eaves, like those of our houses, and
serving to preserve the body of the edifice itself from wet. On the
right hand of the illustration there is an example of the eaves as they
are still to be seen in some of our country places, where the less
picturesque slates have not yet superseded the old thatch. In some
places these eaves extend considerably beyond the walls, and I know of
several instances, especially in North Devon, where a supplementary set
of eaves extends, like a penthouse, throughout the length of the
building, and just above the windows of the ground-floor.
The reader will remark that the projections upon the Myrapetra’s nest
may very well fulfil the office of eaves as that of porches, and not
only shelter the entrances, but serve to shoot the wet off the walls of
the nest.
* * * * *
ON the left hand of the illustration are several instances of eaves as
existing in Nature.
In the centre is the compound nest of the Sociable Weaver-bird of
Southern Africa (_Philetœrus socius_).
This is a dwelling constructed very much after the fashion adopted by
many hymenopterous insects, namely, that each pair of birds make their
own individual nest, but unite with their companions in constructing a
common roof or covering. More than three hundred nests have been found
in a single habitation, and sometimes the birds miscalculate, or rather,
do not calculate the resisting power of the branches, and, when the
rainy season comes, the additional weight of water brings down the whole
edifice with a great crash.
[Illustration: DWELLING OF SOCIABLE WEAVER-BIRD, WITH THATCH.]
[Illustration: THATCHED EGGS OF GOLD-TAILED MOTH.]
[Illustration: THATCHED HOUSE.]
The thatch which covers this congeries of nests is made of the
Booschmannees-grass, whose long leaves and tough wiry stems are
admirably adapted for throwing off water, even though they be not bound
together like our more regularly constructed thatch.
Perhaps the reader may be aware that in the Orang-outan, the Chimpansee,
and other large apes, the hairs of the arms are very long, and point in
different directions, so that if the creature should be caught in a
rain-storm, and, after the manner of its kind, fold its arms on its
breast, with the hands resting on the shoulders, the rain is shot clear
of its body, the hairs performing the duty of eaves.
Both Japan and China have a rain-cloak, constructed on exactly the same
principle as the thatch of the Sociable Weaver-bird. They are nothing
more than successive rows of long grass-blades fastened to a network of
the proper shape. No amount of rain or snow can wet them through, and
they have the advantage of being pervious to the exhalations of the
body, though impervious to external moisture.
In this respect they are greatly superior to our waterproof coats, for,
if the wearer has to undergo much bodily exertion, or is obliged to wear
it for any length of time, he finds his clothing nearly if not quite as
wet as if he had allowed the pure rain to fall on him from the clouds. I
possess specimens of each kind of cloak.
When I procured them they were quite blackened with London smoke, and,
on account of their resistance to water, washing them was a very long
and troublesome business.
Above the nest are two patches of the Booschmannees-grass, as they
appear when laid by the bird.
* * * * *
BELOW the nest is a group of the eggs of the Gold-tailed Moth, whose
nest has already been described. Perhaps the reader wonders where the
eggs are. Owing to the mode in which they are arranged, only a few can
be seen, and are represented by the little white spots in the lower part
of the figure. When the Gold-tailed Moth is ready for the great business
of laying her eggs, she seeks a suitable place, and then piles them up
in the form of a shallow cone. Her task, however, is not yet finished.
Having arranged her eggs, she scrapes off the long downy hairs of the
tail-tuft, and arranges them carefully on the eggs so as to cover them
with a conical thatch, very much resembling that of an ordinary
corn-rick.
The Brown-tailed Moth acts in a similar fashion.
Furs of various kinds act in the same manner, being impervious to wet
during the life of the animal. Such, for example, is the fur of the
Beaver, that of the Capybara, and that of the Seal, which are animals
living in our time. These, however, are exceeded in their thatch-like
powers by the three successive coatings of hair that were worn by the
ancient Mammoth, the outermost being very long and very coarse, and
hanging down in heavy tufts so as to shoot the water from them.
* * * * *
BEING on the subject of roofs, we will take a few more examples of the
roof as anticipated in Nature.
[Illustration: WINGS OF BUTTERFLY.]
[Illustration: TILES OF HOUSES.]
That parallel fibres, whether animal or vegetable, can throw off rain
when properly arranged, has already been shown. Much more is it evident
that flat or partly flat plates will have the same effect, if they be
arranged so that the joints are “broken,” as masons and bricklayers say,
_i.e._ so that the broad part of the upper row of plates overlaps the
junction of two of the plates in the row immediately below it.
* * * * *
ON the right hand of the accompanying illustration are given two
sketches of a modern roof, one slated and the other tiled. The figures
on the left show that this formation has been anticipated by Nature, in
the wonderful system of scales which cover the wings of butterflies and
moths, and to which all their brilliancy of colour is owing. In spite of
their minute size, most being too small to be distinguished by the
unaided eye, they are arranged as regularly as the best workman could
lay the slates or tiles on a roof, and on exactly the same principle.
The shapes of these scales vary in almost every species, but they are
always arranged on the same plan, namely, being placed in successive
rows, each overlapping the other.
In consequence, it is almost impossible to wet a butterfly’s wing with
water. The insect may be plunged beneath the surface, and the long hairs
of the body will be soaked and cling together in a very miserable
fashion. But the water rolls off the wings like rain off a slated roof,
and even if a few drops remain on the surface, they can be shaken off,
and the wing will be perfectly dry.
Mostly these scales are flat, but sometimes they are curved. I have
among my microscopic objects a piece of wing from a South American
butterfly, the scales of which are oblong and bent, just like the curved
tiles shown in the second right-hand figure of the illustration. These
beautiful scales are deep azure or warm brown, according to the
direction of the light.
Perhaps my readers may call to mind that some architects dislike the
flat, square form in which slates are usually put on roofs, and try to
make them less formal.
[Illustration: SHELL OF TORTOISE.]
[Illustration: HEXAGONALLY TILED ROOF.]
Sometimes they take their square slates, and fit them with one of the
angles uppermost, so that each slate looks something like the ace of
diamonds in a pack of cards. Sometimes they are still more ambitious,
and certainly succeed in producing a better effect, by cutting the
slates in hexagons instead of squares, and fixing them as shown in the
right-hand figure of the illustration. Putting aside the familiar
hexagons of the honeycomb, and the apparent hexagons of an insect’s
compound eye, we have in the common Tortoise an example of hexagonal
plates that exactly resembles the slate roofing.
In the next illustration we have a variety of the same principle
exhibited in differently shaped tiles and scales. The figures on the
right hand show the pointed, the square, and the oblong tiles. These
also would answer very well as representations of different forms of
scale armour, the one being intended to throw off rain, and the other to
repel weapons.
On the other side of the illustration are examples taken from the animal
kingdom. First comes the Bajjerkeit, or Short-tailed Manis, which has
already been mentioned, and whose imbricated scales will resist the
blows of any spear or sword. As to my own specimen, when it is struck,
it resounds as if it were a solid plate of metal, and I should think
that during the lifetime of the animal a reasonably strong axe would
not easily make its way through that coat of mail.
Below the Manis are a pair of fish, whose scales, though not so strong
as those of the mammal, yet are arranged in the same manner, and answer
the same purpose. The last figure represents three scale-bands of the
Armadillo, an animal which has already been mentioned. I may as well
state here that in several anthropological museums there are various
portions of defensive armour made from the scale-clad skin of the
Crocodile, Manis, and similar animals.
[Illustration: MANIS.]
[Illustration: FISHES.]
[Illustration: BANDS OF ARMADILLO.]
[Illustration: TILES AND SLATES.]
ARCHITECTURE
CHAPTER III.
THE WINDOW.--GIRDERS, TIES, AND BUTTRESSES.--THE TUNNEL.--THE
SUSPENSION-BRIDGE.
The Window, and its Modifications according to Climate.--Bars and
Tracery.--The Wheel-window and the Caddis.--Curious Structure of
the Caddis-tube.--Object of its Window.--The Girder as applied to
Architecture.--The Radius and Ulna.--The Tie as applied to
Architecture, and its Value.--Combination of the Tie and
Girder.--Structure of the Crystal Palace.--Leaf of the Victoria
Regia.--A Gardener turned Architect.--The Buttress in Art and
Nature.--The Tunnel used as a Passage of Communication.--Natural
Tunnel of the Ship-worm.--The Thames Tunnel.--The Piddock, or
Pholas.--The Driver-ant.--The Suspension-bridge.--The Palm-wine
Maker and his Bridge.--Suspension-bridges of Borneo and South
America.--The Creepers and the Monkey Tribes.--The Spider and
Little Ermine Caterpillar.
THE WINDOW.
Having traced, though but superficially, the chief parts of a building,
such as the walls, the door which is opened through the walls, and the
roof which shelters them, we naturally come to the Windows by which
light is admitted to them, and enemies excluded.
There are, perhaps, few points in Architecture in which such changes
have been made as in the Window, which, instead of being a difficulty in
the way of the architect, is now valued as a means of increasing the
beauty of the building. Taking for example even such advanced specimens
of Architecture as those furnished by Egypt, Greece, and Rome, we find
that the Window is either absent altogether, its place being supplied by
a hole in the roof, or that, when it is present, it was made quite
subordinate to the pillars and similar ornaments of the building.
This fact is, perhaps, greatly owing to the influence of climate. In the
parts of the world which have been mentioned in connection with this
subject, light and heat appear to be rather enemies than friends, and
the object of the architect was to enable the inhabitants of his houses
to avoid rather than to welcome both. Consequently, the Windows were
comparatively insignificant. They were not needed for the purposes of
light or air, those being generally furnished by the aperture in the
roof, and consequently were kept out of sight as much as possible.
But when architects had to build for a sterner, a colder, and a darker
clime, where the sun never assumed that almost devouring heat and light
which in hot countries drive the inhabitants to invent endless devices
for obtaining coolness and shade, a different style of Architecture
sprang up. In this the Window became nearly the most prominent part of
the building: the elements were excluded by glass instead of stone, and
the principal modifications of light were obtained by staining the glass
in various rich colours. Perhaps the Window has attained its culminating
point in the Crystal Palace, which is all window except its foundations.
Partly in order to enable the glass to be inserted, and partly to
increase the beauty of the building, and to avoid the mean appearance of
Windows filled in with plain iron bars crossing each other at right
angles, the interior of the Windows was adorned with stone “tracery,”
varying much according to the epoch of the building.
[Illustration: CADDIS GRATING.]
[Illustration: WHEEL-WINDOW.]
One of the most beautiful forms of the Window is that which is called
the Wheel. The window itself is circular, and the tracery is disposed so
as to bear an exact resemblance to an ornamental wheel, the lines of the
tracery running from the circumference to the centre, just like the
spokes of a wheel. One of these Wheel-windows is shown on the right hand
of the illustration.
On the other side is an object, which at a hasty glance might be taken
for another Window of the same character. It is, however, the work of an
insect, and not of man, and is magnified in order to show its structure
better.
Any of my readers who may happen to be entomologists or anglers, or
both, are familiar with the Caddis-worm of our fresh waters. Most of us
know that the Caddis is the grub or larva of the Stone-fly
(_Phryganea_), an insect haunting the waterside, and so moth-like in its
general aspect that many persons think that it is really a brown moth.
The changes or metamorphoses of these insects are well worthy of notice.
In one respect the Caddis resembles the larva of the Wax-moth, mentioned
on page 151, inasmuch as it has a soft, defenceless body, while the
first three segments are comparatively hard. Like the Wax-moth also, the
Caddis lives in a tube constructed by itself. Instead, however, of
having a long and fixed tube, up and down which it can pass at pleasure,
the Caddis makes a tube only a little longer than its body, and light
enough to be carried about, just as the hermit-crab carries its
supplementary shell. There are many species of Caddis-fly.
The Caddis inhabits fresh waters, and cares nothing whether they be
ponds or running streams. In order to defend its white, plump, and
helpless body from the fishes and other enemies, it constructs a tube
around its body, strengthening it by a wonderful variety of material
according to the locality.
Mostly the tubes are covered with little pieces of stick or grass, or
leaves, while some species use nothing but sand-grains, constructing
with them a tube very much resembling in shape an elephant’s tusk, and
reminding the conchologist of the dentalium shell. But they seem to use
almost anything that comes to hand. Taking only examples found by myself
in a single pond, these cases are formed of sand, stones, sticks,
grass-stems, leaves, shells of small water-snails, mostly the flat
planorbis, the opercula of the water-snail, empty mussel-shells, a
chrysalis of some moth which had evidently been blown into the water
from an overhanging tree, and acorn-cups. The larva, however, does not
seem to be able to fasten together any objects with smooth surfaces, and
though it has been known, when in captivity, to make its cases out of
gold-dust or broken glass, it could not use either material when in the
form of beads.
When it is full-fed, and about to enter the pupal state, it proceeds to
prepare its habitation. As a larva, when it desired to feed, it
protruded its head and the front of its body from the mouth of the tube,
and then crawled about in search of nourishment, dragging the tube with
it, and holding it firmly by means of the claspers with which the end of
the body is furnished. But when it becomes a pupa it is no longer able
to defend itself, and is instinctively compelled to secure its safety in
some peculiar manner.
It cannot fasten up the entrance entirely, because it would not be able
to breathe unless water could pass over its body. Accordingly, it
constructs a grated window precisely like those of the old castles, so
that water can pass freely, while no enemy can gain admittance. Unlike,
however, the grated windows of the castle, which had no pretence to
beauty, the Caddis always constructs its barriers in some definite
pattern. Each species appears to have its own peculiar pattern, but all
agree in making their window, if we may so call it, exactly like a
wheel-window before the glass is inserted.
When the pupa is about to make its final change into the perfect form,
it cuts away the tracery with a pair of sharp jaws, with which it is
furnished for this sole purpose, emerges from the water, throws off the
pupa-skin, and issues forth as a Stone-fly.
GIRDERS, TIES, AND BUTTRESSES.
Next in order come the means by which walls are supported internally by
Girders and Ties, and externally by Buttresses.
* * * * *
OF late years the Girder, in its many varieties, has come into general
use, especially in the construction of railway bridges and similar
edifices.
[Illustration: RADIUS AND ULNA OF HUMAN ARM.]
[Illustration: GIRDER (FROM A HOUSE IN BERMONDSEY).]
On the right of the accompanying illustration is shown the Girder in its
simplest form. The figure was taken from a Girder which is used in
supporting the walls of a large building in Bermondsey. Sometimes a
transverse stay connects the centres of the two curved beams; but it is
seldom needed.
The reader will see that if the interval between the curved beams were
to be filled up, we should obtain a form very like that of the engine
beam described in page 25; while, if we could imagine two such girders
intersecting each other at right angles throughout their length, a
section of the two would exactly resemble the section of the engine beam
as given in the uppermost figure in page 25.
* * * * *
IN the human body there are four admirable examples of the natural
Girder, namely, in the bones of the arms and legs.
On the left hand of the illustration are shown the two bones of the
fore-arm, technically named the “radius” and “ulna.” It will be seen
that these bones are arranged on the principle of the girder. In men who
are especially powerful of grasp, it has been noticed that the curve of
the radius and ulna has been exceptionally bold, while we have it
developed to the greatest extent in the fore-arm of the Gorilla, an
animal whose arms are simply gigantic.
The two bones of the legs, from the knee to the ankle, are arranged in a
similar manner, and are called the “tibia” and “fibula.” The last named
signifies a brooch, and is given to the bone because it is very slender,
nearly straight, and when in its place bears no small resemblance to the
pin of the fibula, or ancient Roman brooch.
Nature, however, has exceeded Art in her girder. Those of man’s
manufacture can only exert their strength in one direction, and would be
of little use if force were to be applied to them in any other
direction. Those of the human body, however, have the capability of
partial revolution on each other at their points of junction, thus
enabling the Girder to apportion its strength according to the direction
of the resistance which it has to overcome.
* * * * *
WE now come to the Ties, _i.e._ those internal beams, whether of metal,
wood, stone, or brick, which prevent walls from falling outwards. There
is no danger of the walls falling inward, but there is very great danger
of their falling outward, especially when the weight or “thrust” of the
roof tends to force them apart.
In some buildings, such as an old country church which I attended for
many years, the architect had openly acknowledged the tendency of the
walls to fall outward, and had counteracted it by a series of great
beams extending completely across the nave and aisle. As he had not even
troubled himself to hide their office, so he did not trouble himself to
conceal the fact that they were tree-trunks, but left them roughly
squared with the axe, lest, if he had squared them throughout their
length, he should have diminished their strength.
The effect of the partially squared beam is, of course, far more
picturesque than that of a completely squared one. The architect,
however, need not have been so careful about strength, for if the beams
had been only half their diameter they would have been just as
effective. The strain on them is by pulling, and not by pushing. Now, as
any one can see by trying the experiment with a splinter of wood--say a
lucifer-match--an enormous power is required to break it by tearing the
ends asunder, while it can be easily broken by pushing them towards each
other.
But for this power of resistance, we should never have had our Crystal
Palace. That apparently intricate, but really simple (and the more
beautiful for its simplicity), intersection of beams and lines
diminishing in the distance to the thickness of spiders’ webs, is
nothing more than a combination of the Girder and Tie, the two together
combining lightness and strength in a marvellous manner.
The story of the Crystal Palace is now so well known that it need not be
repeated in detail. A vast building was required for the Exhibition of
1851, and not an architect was able to supply a plan which did not
exhibit some defect which would make the building almost useless.
Suddenly a Mr. Paxton, who was a gardener, and not an architect,
produced (on a sheet of blotting-paper) a rough plan of a building on a
totally new principle, and not only fulfilling all the requisite
conditions, but being capable of extension in any direction and to any
amount. There have been very few bolder conceptions than that of making
iron and glass take the place of brick, stone, and timber, and the
result fully justified the expectations even of the inventor.
How a gardener suddenly developed into an architect remains to be seen;
and, indeed, in this case the architecture was the result of the
gardening, or rather, of practical botany applied to art. Some years
before the invention of the Crystal Palace, that magnificent plant, the
Victoria Regia, had been introduced into England. Its enormous leaves,
with their wonderful power of flotation, caused a great stir at the
time, and some of my readers may remember a sketch which was engraved in
the _Illustrated London News_, and which represented a little girl
standing on one of these leaves as it floated on the water.
[Illustration: LEAF OF VICTORIA REGIA (REVERSED).]
[Illustration: CRYSTAL PALACE.]
Mr. Paxton saw how this power was obtained, and the result was that he
copied in iron the lines of the vegetable cellular structure which gave
such strength to the Victoria Regia leaf, and became more eminent as an
architect than he had been as a gardener. The capabilities of the
Crystal Palace had lain latent for centuries, but the generalising eye
of genius was needed to detect it. A thousand men might have seen the
Victoria Regia leaf, and not thought very much of it; but the right man
came at the right time, the most wonderful building in the world sprang
up like the creation of a fairy dream, and the obscure gardener became
Sir Joseph Paxton.
I have no doubt that thousands of similar revelations are at present
hidden in Nature, awaiting the eye of their revealer.
* * * * *
NOW we come to the principle of the Buttress, _i.e._ giving support to
the exterior, instead of the interior, and strengthening the walls by
pushing them together, instead of pulling them together.
Putting aside the “flying” buttress, which is simply one buttress
mounted on another to support the clerestory walls, the structure of the
ordinary buttress is simple enough.
The most primitive form of the buttress is often found in country farms,
where the farmer sees the walls of his barns and outhouses leaning
suspiciously on one side, and, instead of going to the root of things,
props them up by a stout pole or beam.
This, however, can be nothing but a temporary arrangement, especially as
beams have a tendency to rot, and their ends to sink into the earth by
the gradual pressure of the wall. The genuine buttress was therefore
evolved, the basal part being very thick and heavy, and the upper part
comparatively thin and slight. Simple as a buttress looks, much skill is
needed in making it, and if it be not rightly built, it does infinitely
more harm than good.
A case in point occurs within a short distance of my house. The walls of
an ancient edifice having shown symptoms of yielding, and some ominous
cracks made their appearance, a couple of very sturdy buttresses had
been erected, in order to stop further damage. Unfortunately, the
builder was ignorant of the principles of architecture, and though he
made the buttresses very strong and massive, he omitted to make a solid
foundation on which their bases should rest. Consequently he only hung
the buttresses, so to speak, on the wall, and helped to tear it asunder
by the additional weight.
[Illustration: PADDLE-WOOD TREE.]
[Illustration: BUTTRESSES.]
* * * * *
NATURE, as well as Art, supplies her buttresses. In our own country we
find the natural buttress more or less developed in our trees, as it is
wanted.
Take, for example, any plantation, and examine the trees. It will be
found that those in the centre, which are sheltered on all sides from
the force of the wind, shoot up straight towards the light, have
comparatively slight and slender stems, and occasionally display such
energy in forcing themselves upwards, that when two branches find that
there is not room for both, they form a sort of alliance, fuse
themselves together, and force their united way towards the sky.
Take, however, the trees in the outside rows of the plantation, and see
how they throw out their straight roots and branches towards the
outside, and how, on the inside, their trunks are as smooth and their
roots as little visible as those of the trees that grow in the centre of
the plantation.
Almost any tree will develop itself in this fashion, showing that
instinct can rule the vegetable as well as the animal world.
There is, however, a South American tree which far surpasses any of our
trees in its power of throwing out spurs or buttresses, principally, I
presume, because it may have to endure the fiercest storms from any
quarter and at any time. So bold are these projections that several men
would be hidden if standing between two of them, and so numerous are
they that if a section of the tree were taken at the base of the ground,
it would resemble a conventional star or asterisk, *, rather than an
ordinary tree-trunk, O.
The scientific name of this curious tree is _Aspidomorpha excelsum_.
The natural buttresses are so thin and so wide that they look like large
planks set on end, with one edge against the tree. Indeed, they are used
as planks, nothing more being required than to cut them from the tree.
This is very easy, as, while the wood is green, it is so soft that a
blow from a “machete,” or native cutlass, is sufficient to separate it.
With the same instrument the native makes these flat planks into paddles
for his canoe, the soft wood yielding readily even to the imperfect edge
of the rude tool. When the wood dries, it becomes very hard, light, and
singularly elastic, all these properties qualifying it for its object.
I have several of these paddles in my collection. They are much prized
by the natives, and are always stained in various patterns with red and
black dyes.
In consequence of the use which is made of this tree, it goes by the
popular name of “paddle-wood.”
THE TUNNEL USED AS A PASSAGE.
As to this division of the subject, I have not been quite sure where it
should be placed, but think the present position a tolerably appropriate
one.
We have already, in the igloo of the Esquimaux and the winter dwelling
of the seal, found examples of the Tunnel when used as an appendage to
the houses and a means of security. We now come to the Tunnel as
affording the means of locomotion.
[Illustration:
TUNNEL OF ANOMMA.
PHOLAS.
SHIP-WORM.]
[Illustration: RAILWAY TUNNEL.]
Take, for example, our own railway system. Had it not been for the power
of tunnelling, the railway would have lost nearly its whole value, for
it would have been restricted to local districts, and could not have
penetrated, as it now does, to all parts of the country, without
reference to hill, dale, or level ground. Our present system of
engineering has wonderfully developed the capability of tunnelling. In
former times it was thought a most wonderful feat to drive a tunnel
under the Thames, while in these days the tunnel through Mont Cenis has
been completed, and we are hoping to make a submarine tunnel from
England to France.
* * * * *
IN Nature we can find many examples of Tunnels used for similar
purposes. The silken tunnel of the Wax-moth larva has already been
mentioned, and we now come to Tunnels where earth in some form, and not
silk, is the material of which they are constructed.
The lowermost figure on the left-hand side of the illustration
represents that well-known and most destructive burrower, the Ship-worm
(_Teredo_), which, by the way, in spite of its popular name, is not a
worm, but a mollusc. This creature has a peculiar interest for
engineering, inasmuch as its mode of working gave Brunel the first idea
of subaquatic tunnelling in loose, sandy soil, just as the Victoria
Regia leaf gave to Paxton the idea which afterwards developed into the
Crystal Palace.
The plan adopted by the Ship-worm is at the same time simple and
effective. It feeds upon wood, and gradually eats its way through almost
any timber that may be submerged. It does not, however, merely bore its
way through the timber, but lines its burrow with a coating of hard,
shelly material. Taking this hint, Brunel proceeded in the same fashion
to drive his tunnel through the very ungrateful soils which form the bed
of the Thames.
He built a “shield,” as he called it, of iron, exactly fitting the
tunnel, and divided into a number of compartments, each of which could
be pushed forwards independently of the others. In each compartment was
a single workman, and, as he excavated the earth in front of him, he
pushed forward his portion of the shield, while the interior was cased
with brickwork, just as a Teredo tunnel is cased with shell.
* * * * *
ABOVE the Teredo is represented another marine tunnel-maker, as it
appears in its burrow.
This is the mollusc popularly known as the Piddock, and scientifically
as _Pholas dactylus_. It may be found abundantly in all our chalk
cliffs, boring its tunnels deeply into the stone, and aiding the sea in
its slow, but never-ending task of breaking down the cliffs on one
side, while it gradually rears them up on another. As the material into
which the Piddock burrows is so hard, there is no need for lining the
tunnel, as is done by the Teredo. In this point, too, our engineers
follow its example. When their tunnels pass through comparatively soft
ground, they line it with masonry, proportioning the thickness of the
lining to the looseness of the soil. But, when they come to solid rock,
they are content with its strength, and do not trouble themselves about
the lining.
The mode of action adopted by the Pholas has long been a disputed point,
and even now appears to be not quite settled. I think, however, that
William Robertson has proved by his experiments that the shell and the
siphon are both brought into requisition. The shell perpetually rotates
in one direction, and then back again, just like the action of a
bradawl, and, by the file-like projections on its surface, rasps away
the chalk, converting it into a fine powder. This powder, being of
course mixed with water, passes into the interior of the animal, and is
ejected through the siphon.
There are many species of Pholas which burrow into various substances,
even in floating cakes of wax and resin. The same species, too, will
burrow into different substances, and it is worthy of notice that those
specimens which burrow into soft ground attain a much larger size, and
their shells are in better preservation, than those which force their
way through hard rock.
* * * * *
THE uppermost figure represents a very remarkable tunnel, having the
peculiarity of being built instead of sunk. It is the work of an African
Ant belonging to the genus Anomma, and popularly known as the
Driver-ant, because it drives away every living creature which comes
across its course of march.
There are many Ants which seem to rejoice in the full blaze of the
tropical sun, running about with ease on rocks which would scorch and
raise blisters on the hand if laid on it, and finding no difficulty in
obtaining the moisture needful for the mud walls of their habitations.
But the Driver-ants cannot endure the sun, and, unless compelled by
necessity, will not march except at night, or at all events during
cloudy days. Should, however, they be absolutely forced to march in the
sunshine, they construct as they go on a slight gallery, which looks
very much like the lining of a tunnel stripped of the surrounding earth.
If their path should lead them to thick herbage, sticks, &c., which form
a protection from the sun, the Driver-ants do not trouble themselves to
make a tunnel, but take advantage of the shade, and only resume the
tunnel when they reach the open ground.
Sometimes, when they are on a marauding expedition, they construct a
tunnel in a very curious manner, their own bodies supplying the
materials. The reader must know that there are several classes of these
insects, varying in size from that of a huge earwig to that of the
little red ant of our gardens. The largest class seem to care little
about the sunshine, the protection being mostly needed by the workers.
The following is Dr. Savage’s account of their proceedings:--
“In cloudy days, when on their predatory excursions, or migrating, an
arch for the protection of the workers is constructed of the bodies of
their largest class. Their widely extended jaws, long, slender limbs,
and projecting antennæ, intertwining, form a sort of network that seems
to answer well their object.”
“Whenever an alarm is given, the arch is instantly broken, and the Ants,
joining others of the same class on the outside of the line, who seem to
be acting as commanders, guides, and scouts, run about in a furious
manner in pursuit of the enemy. If the alarm should prove to be without
foundation, the victory won, or danger passed, the arch is quickly
renewed, and the main column marches forward as before, in all the order
of an intellectual military discipline.”
How they should be able to direct their course, and to chase an enemy,
is not easy to understand; for, as far as is known, they are absolutely
blind, not even an indication of an eye being seen.
THE SUSPENSION-BRIDGE.
The mention of these Ants brings us to another point in architecture. We
have already seen that they can not only build arched tunnels, but also
can form their own bodies into arches, and we shall presently see how
they can form themselves into Suspension-bridges. We will, however,
first take the Suspension-bridge, and its vegetable origin, before
passing to the animal.
[Illustration: CREEPERS.]
[Illustration: SUSPENSION-BRIDGE.]
I have little if any doubt that the modern Suspension-bridge, with all
its complicated mathematical proportions, was originally suggested by
the creepers of tropical climates. There are few points in a tropical
forest, no matter in what part of the world, more striking than the
wonderful development of the creeping plants. The trees are very much
like those of our own forests, and are in no way remarkable, but the
creeping plants form the chief feature of the woods.
They extend themselves to unknown lengths, crawling up to the very
summit of a lofty tree, hanging down to the very ground, if not caught
by a midway branch, running along the earth, making their way up another
tree, and so on _ad infinitum_. They interlace with each other, forming
almost impenetrable thickets, as has already been mentioned while
treating of Nets, and there is scarcely a tree that is not connected
with its neighbour by means of these wonderful creeping plants.
Of course the monkey tribes make great use of them in passing from one
tree to another, thus being able to avoid the ground, which is never to
a monkey’s liking. Man, therefore, copies the example of the monkey, and
makes use, either of the creepers themselves, or of ropes stretched from
tree to tree in imitation of them.
In some parts of the world, where palm wine, or “toddy,” is
manufactured, the native has recourse to an ingenious device which saves
a vast amount of exertion. As the calabash which receives the juice of
the palm-tree is always fixed at a considerable height, and as each tree
only yields a limited supply, the toddy-maker would be obliged to ascend
and descend a great number of trees before he could collect his supply
of palm-juice.
In order to save himself trouble, he has the ingenuity to connect the
trees with each other by two ropes, the one about six feet above the
other. He then has only to ascend once, and descend once, for he ascends
one tree, and by means of the ropes passes from tree to tree without
needing to descend.
The mode of traversing these ropes is simple enough, the lower rope
serving as a bridge, along which the man walks, and the upper rope being
held by the hands. Those who see these palm-wine makers for the first
time are always greatly struck. At some little distance the ropes are
quite invisible, and the man appears to be walking through the air
without any support whatever.
In Borneo the Rattan is continually put in requisition as a bridge. It
runs to almost any length, a hundred feet more or less being of little
consequence; it is lithe and pliant, and so strong that it can hardly be
broken. The “canes” formerly so much in vogue among schoolmasters, and
now so generally repudiated, are all cut from the Rattan. Chiefly by
means of this natural rope, the Dyak of Borneo flings his rude
suspension-bridges across chasms or rivers, and really displays a
wonderful amount of ingenuity in doing so.
The one fault of these bridges is their tendency to decay, or perhaps to
be eaten by the multitudinous wood-eating insects which swarm in that
country. However, the materials cost nothing at all, and time scarcely
more, so that when a bridge breaks down, any man can fit up another at
the expense of a few hours’ work. As, moreover, the Dyaks have a curious
way of building their houses on one side of a ravine, they find that a
bridge of this kind saves them the trouble of descending and ascending
the ravine whenever they wish to visit their house.
In many parts of America the Suspension-bridge is almost a necessity.
The country is broken up by vast clefts, technically called “cañons.”
These cañons are ravines in the rocky ground, with sides almost
perpendicular. For the greater part of the year they are dry, but
sometimes, and without the least warning, they become the beds of
roaring torrents, rising to some thirty or forty feet in height, and
carrying away everything before them.
Over these ravines are thrown suspension-bridges made almost entirely of
creepers, and loosely floored with rough planks. Although they are very
strong, they appear to be very fragile, and even under the tread of a
human being swing and sway about in a manner that always shakes the
nerves of one who is unaccustomed to them. Yet, even the mules of the
country can cross them, the animals picking their way with the wonderful
sure-footedness of their kind, and not in the least affected by the
swaying of the bridge.
Passing from the vegetable to the animal world, we revert to the
Driver-ants, which have already been mentioned. It has been seen that
their soldier-ants can, with their own bodies, form a tunnel, under the
shade of which the workers can pass, and we have now to see how they
can, with the same materials, form a suspension-bridge.
It often happens that on their march they come to water, and, as they
always advance with total disregard of difficulties, they must needs
invent some very ingenious way of overcoming the difficulty. One of them
climbs a branch which overhangs the water, clasps the undermost twig
very tightly, and allows itself to hang from it. Another at once
follows, and suspends itself from its comrade in like manner, the
powerful and sicklelike jaws doing their duty as well as the legs. A
chain of Ants is thus speedily formed. When the lowermost Ant touches
the water, it merely spreads all its legs, and awaits the development of
events. Another runs over it, holds to the first Ant by its hind-legs,
and stands in the water, spreading its limbs as much as possible over
the surface. Ant after Ant descends, until quite a long chain of the
insects is formed, and is swept downwards with the stream. By slow
degrees the chain is lengthened, until the Ants at its head are able to
seize the bank on-the opposite side of the water. When they have
succeeded in doing so, the bridge is complete, and over that living
bridge will pour a whole army of Driver-ants.
Even in those cases where this mode of travelling would be too perilous
on account of the rapid torrent, the Ants contrive to suspend themselves
in long strings until they effect a communication with the trees of the
opposite bank.
It is, perhaps, needless to give more than a passing reference to the
Suspension-bridges made by Spiders, by means of which they can traverse
considerable distances. The similar bridge of the Little Ermine
Caterpillar has already been mentioned, when treating of the subject of
Double Walls.
ARCHITECTURE
CHAPTER IV.
LIGHTHOUSES.--THE DOVETAIL.--THE DAM.--SUBTERRANEAN DWELLINGS.--THE
PYRAMID.--MORTAR, PAINT, AND VARNISH.
The Eddystone Lighthouse: its Position, and the Difficulties of
building it.--Destruction of successive Lighthouses.--Smeaton’s
Idea of Form borrowed from the Tree-trunk.--Mode of
building.--Rooting it into the Rock.--Principle of the
Dovetail.--Bones of the Human Skull, and their Articulation.--The
Dam, and its Uses to Man.--The Lock and the Water-mill.--Dam of the
Beaver: its Objects and Mode of Construction.--Popular Errors with
regard to the Dam.--Subterranean Dwellings.--The Indian Palace, and
its Use in Summer.--Subterranean Dwellings in Kamschatka, and their
Use in Winter.--The Wood or Horse Ant, and its double
Dwelling.--The upper and lower Nests used according to the Amount
of Warmth required.--Section of the Nest, and a Glimpse into its
Interior.--The Pyramid.--Derivation of its Name.--Natural Objects
from which the Form was derived.--Subaquatic Mortar or Cement, and
its Use to Man.--Subaquatic Cement used by the Caddis, the
Stickleback, the Terebella, the Sabella, the Serpula, and
others.--Paint and Varnish, and their Utility to Man.--Propolis as
used by the Hive Bee, and the Source whence it is obtained.
We now come to some points in Architecture which cannot well be grouped
together, and must therefore be treated as Miscellanea.
Our first example is one which was avowedly based upon an imitation of
Nature, namely, the celebrated Eddystone Lighthouse, and we shall see
that in two points--first its form, and next the mode in which the
stones were fixed together--Nature had been closely followed by the
architect.
Unlike ordinary lighthouses, this edifice had to be constructed so as to
endure the full force of waves as well as wind. A few miles from the
southern coasts of Devon and Cornwall there is a rock which in former
times greatly endangered the ships which passed along the Channel.
Several attempts were made to build a lighthouse on this dangerous spot.
Winstanley’s lighthouse, which was finished in 1700, was wholly swept
away three years later, together with the architect himself, and some
workmen who were engaged in repairs. So terrific is the force of the
elements on this spot, that the lighthouse was entirely destroyed, and
the only vestiges of it that were ever discovered were some iron bars
and a piece of chain.
Another lighthouse was built a few years afterwards, but was burned
down, it being of wood instead of stone. At last the work was put into
the hands of Smeaton, who saw that he must build on a totally new plan.
He took for his model the trunk of a tree, and determined to build his
lighthouse of the same form as the tree-trunk, and to fasten it into the
rock just as a tree is fastened by its roots. Accordingly, he struck out
a new principle in the construction of such edifices, and his model has
been followed ever since. The reader will see, by a glance at the
illustration, how close is the resemblance in external form. I may
mention that the tree in question was sketched from one in a paddock
opposite my house.
[Illustration: TREE-TRUNK. EDDYSTONE LIGHTHOUSE.]
Having settled the form of the lighthouse, and made it like a
tree-trunk, the next business was to fix it firmly in the rock, and, in
fact, to give it roots of stone. For this purpose, he made the base of
the edifice as wide as the rock would allow, so as to correspond with
the wide base of a tree-trunk, and traced a circle of about ninety feet
in circumference. Instead, however, of merely laying the stones as is
usually done, or even letting them into holes cut in the rock, he hit
upon a singularly ingenious device, whereby the building was practically
a single stone.
Instead of cutting the stones square or oblong, as is usually done, he
had them made so as to “dovetail” into each other, much after the
fashion of a child’s puzzle toy, or the junctions at the edge of a box.
Thus, each stone fitted into those around it, while the lowest tier was
dovetailed in similar fashion into the rock.
[Illustration: SUTURES OF SKULL
SECTION OF EDDYSTONE LIGHTHOUSE
DOVETAILED BOX]
The stone employed was that which is called Moorstone, a very hard
variety of granite. Each course of stones was carefully fitted together
on shore, and their accuracy tested, and they were then taken to the
Eddystone rock, and fixed in their places. Beside using these
precautions, Smeaton fixed the stones in their place with the strongest
cement, and furthermore fastened the stones together and united the
several courses by strong oak treenails and iron clamps. As none of the
stones weighed less than a ton, and some of them were double that
weight, the strength of such an edifice may be imagined.
The accompanying illustration shows the arrangement of these dovetailed
stones in one of the courses. It will be seen that the central stone
must be laid first, and then the others arranged round it. The whole
edifice is rather more than eighty-five feet in height, so that the
elements have every chance of demolishing it, as they did that of
Winstanley. More than a hundred years have now passed since it was
built, and, although the fury of the tempest has been such that the
waves have washed completely over its summit, it stands as firmly as it
did when it was finished in 1760.
* * * * *
WHETHER the original inventor of the “dovetail” took his idea from
Nature I cannot say, but he certainly might have done so. On the left of
the illustration is part of a human skull.
The skull is not, as many persons seem to think, made of a single bone,
but it is composed of many bones, united by “sutures,” which are, in
fact, natural dovetails. Although in early life these sutures are
comparatively loose, they hold the various parts together so firmly,
that if the head be violently struck, the bones may break, but the
sutures do not give way.
Perhaps some of my readers may ask how it is possible to take a skull to
pieces without cutting it or fracturing the sutures. It is done in a way
equally simple and ingenious. The skull is filled through the opening
with dried peas, and then sunk under water. The peas expand with the
moisture, and, as they exert an equable force in all directions, they
slowly and quietly pull the sutures asunder, without injuring the bones.
THE DAM.
In many human operations, where a certain depth of water is required in
a running stream, the reasoning powers of man have enabled him to attain
his object by building a dam, or obstacle across the stream, which
forces the water to rise to its level before it can find a passage.
Such, for example, are the Locks which render rivers navigable, and
allow even the heavily laden barges to traverse miles of water which
would otherwise have been closed to them.
Those mills, again, which are worked by water need that a sufficient
amount of water should be ready in order that it may by its weight force
the wheel round. Such a Dam is shown on the right hand of the
illustration, the height to which it raises the water being shown by the
level of the stream below the Dam, and that of the water as it tumbles
over in a miniature cascade.
Putting aside the natural dams made by accumulations of the various
debris that are washed down by a swollen stream, and which sometimes
raise the water to a very great height, we have an example of a natural
dam in the curious structure made by the Beaver, for the same purpose as
that of the lock in the mill-stream, namely, to insure a depth of water
sufficient for the needs of the beings that make them.
Every one has heard of the Beaver’s dam, but there is so much
misconception on the subject, that a few words will not be out of place.
Ingenious as is the animal in the construction of its dam, it is not
nearly so accomplished an architect as was once supposed. We were told
in the earlier books of Natural History that the Beaver felled trees,
cut off their branches into convenient lengths, and sharpened one end,
like an ordinary stake. Then they were said to drive the sharp end of
the stakes into the bed of the river, to set them side by side, to
interweave smaller branches among them, and lastly, to fill up the
interstices with mud, leaves, and similar materials. In fact, they were
supposed to build a “wattle-and-daub” wall, like that which is in use at
the present day in Southern Africa.
[Illustration: DAM MADE BY BEAVER. DAM MADE BY MAN.]
The Beaver does nothing of the kind. It needs a dam, and it makes one
which is far stronger than the wattle-and-daub could be. It begins by
felling a tree, and letting it lie across the stream, in some place
where the banks are high and tolerably steep. A bend of the river is
usually chosen for the new dam. Should not the tree be long enough for
the Beaver’s purpose, two trees are felled, one on either side, so that
their branches meet in the middle.
These branches, and not any supposed stakes, are really the upright
supports of the dam. The trees being thus laid, the Beaver cuts down
branches from four to six feet in length, and lays them horizontally
among the boughs of the fallen trees. Having thus made the foundations,
so to speak, of its dam, the Beaver then proceeds to fill in the spaces
with roots, grass-tufts, leaves, mud, and, indeed, almost anything on
which it can lay its paws.
After this, the Beaver has to take but little trouble, for the stream
itself becomes a silent, slow, but constant labourer, lodging floating
debris against the dam, and making a sloping bank which much adds to its
strength. By degrees, seeds that lodge on the dam spring into life, and
their roots act like chains, binding the materials more closely
together. Willow twigs too, if they lodge on the dam and be left
undisturbed, are sure to “strike,” as the gardeners say, and further to
bind the structure together.
It is evident, from this short description, that the lower part of the
dam is more solid than the upper. In fact, the floods are tolerably sure
to wash away some eight or ten inches of the upper part every year, and
the Beavers have to make it afresh. The height of these dams is not
nearly so great as is generally supposed. Mr. Green, a practical
trapper, states that the highest which he ever saw was only four feet
six inches in height, and that the average is under three feet.
The house of the Beaver is made on the same principle as the dams. Every
one knows that when sticks have been in the water for any length of
time, they become saturated and sink. These sticks are chosen by the
Beaver as the material for its house, and are laid horizontally in the
water, the heaviest being reserved for the roof, so as to make it strong
enough to ward off the attacks of predacious animals. As with the dam,
mud, leaves, &c., are used to consolidate the edifice, but no mud can be
seen from the outside, the animal always finishing off with a number of
heavy logs laid on the roof.
SUBTERRANEAN DWELLINGS.
I do not intend in this place to take up the whole subject of
Subterranean Dwellings, but only to point out cases where the use of the
Subterranean Dwelling depends on the climate of the locality and the
time of year, it being sometimes used and sometimes neglected, sometimes
inhabited for the sake of warmth, and sometimes for that of coolness.
In various parts of India there are some most remarkable Subterranean
Dwellings. They are more than mere dwellings, and are, in fact,
magnificent palaces, sunk so deeply in the earth that very little more
than their roofs appear aboveground. When, however, a visitor descends
the stairs that lead to the interior of the palace, he finds it
spacious, and with tiers of chambers one below the other, very much like
the wasp-nest which has already been described. Nussur-ed-deen, the
second King of Oude, had several of these palaces, but very seldom
visited them, he having endeavoured to Europeanise himself as much as
possible, and to cast off his native customs. He used occasionally to
visit them, but it was only out of etiquette, and he never really lived
in them.
[Illustration: SUBTERRANEAN ANTS’ NEST. SUBTERRANEAN HOUSE OF
KAMSCHATKA.]
However much he might have rejected the ancient customs, it is evident
that in this case, at least, he was punishing himself in rejecting these
summer dwellings, which are always cool, and where, if one set of
apartments is too warm, nothing is easier than to descend to the next.
* * * * *
THIS dwelling is made for the sake of coolness in summer. Another
subterranean dwelling is made for warmth in winter, the non-conducting
properties of the earth being in both cases brought into play. This is
the winter dwelling of the inhabitants of Kamschatka.
During the summer-time the Kamschatdales live in comparatively slight
huts mounted on poles, and having the floor some ten feet from the
ground.
During the winter, however, they live in habitations of a very different
character.
In order to make these houses, they begin by digging a large hole in the
ground, about nine or ten feet in depth. This they line with poles and
sticks, making, in fact, a wall as of a house. A stout conical roof is
then raised over the hole, and upon the roof earth is thickly strewn and
beaten down, just as has been mentioned when treating of the ice-house.
The only access to this strange house is by a circular aperture in the
centre of the conical roof, serving at once the purpose of a door, a
chimney, and a window. A notched pole answers as a ladder, a low wooden
dais placed against the wall serves as a bed or a chair, for there is no
other, and a few stones placed together act as a fireplace.
* * * * *
IN looking at both these subterranean dwellings, I could not but be
reminded of a very common insect which has a double dwelling, one moiety
being aboveground, and the other moiety below it. This is the common
Wood-ant (_Formica rufa_), whose large, leafy hills are so plentiful in
some of our woods. On account of its size, this species is sometimes
called the Horse-ant.
At first sight the nest looks something like a small haycock, made
entirely of chopped grass. When examined more nearly, it will be found
to consist mostly of grass-stems, little bits of stick, and leaves.
Those of the fir are in great request, for when they are dry they are
very light, and their form enables the Ant to interweave them with each
other, so as to form the necessary tunnels and galleries which line the
interior of the nest. The materials seem most unpromising, but they are
used with wonderful skill, such as no human fingers could equal.
After a little while a number of entrances into the nest are visible.
They are almost invariably sheltered by projecting leaves, which act as
porches, so that when the nest is viewed from above, they are almost
entirely hidden. Each of these openings runs into one of the main
galleries of the nest, and from thence issues a perfect labyrinth of
passages.
This, however, is only half the nest, for the galleries and tunnels
extend far beneath the surface of the earth, and have sundry enlarged
portions or chambers wherein the immature pupæ may lie during their
period of helplessness.
Owing to the very loose structure of the upper nest, and the tendency of
the earth to fall into the galleries of the lower nest, it is very
difficult to obtain a trustworthy view of the interior. Perhaps I may
here be allowed to extract a passage from my “Insects at Home,” the
description of the nest and its interior having been written almost on
the spot:--
“I have, however, succeeded in obtaining an excellent view into the
interior of a Wood-ants’ nest, though it was but a short one.
Accompanied by my friend Mr. H. J. B. Hancock,[B] I was visiting some
remarkably fine Wood-ants’ nests near Bagshot. We took with us a large
piece of plate glass, placed it edgewise on the top of an Ant-hill, and,
standing one at each side, cut the nest completely in two, leaving the
glass almost wholly buried in it.
[B] Now Sir Henry J. Burford Hancock, Chief Justice of Gibraltar.
“After the expiration of a few weeks, during which time the ants could
repair damages, we returned to the spot, and, with a spade, removed one
side of the nest as far as the glass, which then served as a window
through which we could look into the nest. It was really a wonderful
sight.
“The Ant-hill was honeycombed into passages and cells, in all of which
the inhabitants were hurriedly running about, being alarmed at the
unwonted admission of light into their dwellings. In some of the
chambers the pupæ were treasured, and these chambers were continually
entered by Ants, which picked up the helpless pupæ, and carried them to
other parts of the nest where the unwelcome light had not shown itself.
“Unfortunately this view lasted only a short time. Owing to the partial
decomposition of the vegetable substances of which the Ants’ nest is
made, the interior is always hot and always moist. Now, the day on which
we visited the nest happened to be a cold one, and, in consequence, the
moisture of the nest was rapidly condensed on the inner surface of the
glass, and in a few minutes completely hid the nest from view, leaving
me only time to make a rapid sketch. Unfortunately some one discovered
the plate of glass and stole it.
“Next time that I examine a Wood-ants’ nest, I shall take care to
insert the glass exactly east and west, and shall open its southern side
towards noon on a hot sunshiny day, so that the rays of the sun may warm
the glass and prevent evaporation.”
Many other creatures make subterranean dwellings, but the Wood-ant is
remarkable for possessing a double dwelling, the two portions
communicating with each other, and capable of being used according to
the degree of heat required.
THE PYRAMID.
We have already seen how the Eddystone lighthouse was the precursor of
many similar buildings all, like their predecessor, having their form
copied, with more or less strictness, from the outlines of a tree-stem.
[Illustration: NATURAL MOUNTAIN.]
[Illustration: ARTIFICIAL MOUNTAIN, OR PYRAMID.]
Another form of building which was intended for endurance, and, indeed,
is the most enduring of all shapes, is the Pyramid.
We are all familiar with the simple, yet grand outlines of the Pyramids
of Egypt, whose vast antiquity takes us back to the times of Isaac and
Joseph, and which seem capable of resisting the effects of Time, the
universal destroyer, for thousands of years yet to come.
We may ask ourselves what was the natural object from which the Pyramid
was copied. The name itself, which is formed from a Greek word
signifying fire, shows that a flame was thought to have furnished the
idea of this form of building. I cannot, however, but think that the
flame had little, if anything, to do with it, and that the real model
may be found in the hills which have been formed by Nature.
Examples of the Pyramids and the Hills are given in the accompanying
illustration.
SUBAQUATIC MORTAR.--PAINT AND VARNISH.
Having now disposed of the chief points in Architecture, we take some of
the subsidiary details.
Of late years, when the traffic between different continents has so
largely extended itself, and when shipping has increased both in the
numbers and dimensions of the vessels, it is absolutely necessary that
we should have harbours and docks enlarged and multiplied sufficiently
to meet the calls upon them.
[Illustration: CADDIS. TEREBELLA. SERPULA. SUBMARINE MORTAR.]
Now, it is comparatively easy to construct a building on shore, for all
the mortars and cements which are used for the purpose of fastening the
stones together are applied when wet, and incorporate themselves with
the stones as they dry. But to make a mortar which could be applied
while the stones were under water, and would “set” while beneath the
surface, was a task not easily to be overcome. Yet it has been done so
effectively that at the present day we can build beneath the surface of
the water as securely, though not as rapidly, as if the stones had been
laid on dry ground.
Several such mortars are now known, and, as is so often the case with
human inventions, have been anticipated in Nature.
We have already seen how the Caddis-worm of the fresh waters can cement
together, while under water, the various materials of which its tubular
house is formed. The different Sticklebacks perform similar feats, no
matter whether they inhabit fresh or salt water.
All those who take an interest in the productions of the seashore will
have noticed upon our coasts the flexible tube of the Terebella, with
its curiously fringed ends. This tube, as any one may see at a glance,
is composed of grains of sand and similar materials, fastened strongly
together by a kind of cement exuded from the worm, and possessing the
property of hardening under water. As on some of our coasts fragments of
shell are used for the tube, the worm goes by the popular name of
Shell-binder.
If one of these worms be taken out of its tube, placed in a vessel with
sea-water and a quantity of sand, broken shells, and little pebbles, the
mode of building will soon be seen. At the extremity of the head are a
number of extremely mobile tentacles, and these are stretched about in
all directions, seizing upon the particles of sand and shell, seeming to
balance them as if to decide whether they are suitable for the tube, and
then fixing them one by one with the cement which has already been
mentioned.
Generally speaking, the Terebella works only in the evening, but, if it
be hastily deprived of its tube, it cannot help itself, and is perforce
obliged to work while it can. It is worthy of remark that the Terebella,
although, as a rule, it lives in a tube all its life, is capable of
swimming with the usual serpentine motion of marine worms, and, when
taken out of its tube, rushes about violently, and soon exhausts itself
by its efforts.
Along most of our rocky seashores may be seen vast quantities of a sort
of hardened sand, penetrated with small tubes. On a closer examination
this sand-mass is resolved into a congeries of tubes, matted and twisted
together, and each being the habitation of a marine worm called the
Sabella. This name is derived from a Latin word signifying sand, and is
given to the worm in allusion to the material of which it makes its
habitation.
Like the Terebella, the Sabella uses its tentacles for the purpose of
building the tubes, which are much stiffer than those of the Terebella.
They are strong enough, indeed, to give the feet a firm hold while
traversing the rocks, and this, is a matter of no small moment when the
tide is coming in, and the shore has to be regained without loss of
time.
Then we have other marine worms, known as Triquetra and Serpula, which
make tubes in a somewhat similar manner, but of very fine materials and
very strong cement, so that the tube is nearly as hard as stone.
Space would fail me if I were to enumerate these creatures at greater
length, but enough has been said to show that man’s invention of
subaquatic cement has been anticipated in Nature by the inhabitants both
of salt and fresh water.
* * * * *
WE now come to the subject of Paint and Varnish. Putting aside their use
as a means to increase the beauty of the object to which they are
applied, we will view them in the light of preservatives, and
acknowledge the truth of the old Dutch proverb, that “Paint costs
nothing.” Certainly, when the wood to which it is applied is thoroughly
dry from within, it not only costs nothing, but repays itself over and
over again as a preservative of the wood, and a defence against moisture
from without.
The instances in which Paint is applied to wood are too numerous to be
mentioned. Perhaps some of my readers may remember the case of the naval
captain who, on taking command of his ship, was supplied, according to
custom, with exactly half the amount of paint required for her. The
invariable etiquette had been that the captain supplied the remaining
half at his own cost. But the officer in question was not at all
disposed to be “put upon,” and was a thorn in the sides of the “Naval
Lords.”
Finding, by actual measurement, that the paint supplied to him was only
half the amount which was really needed for the ship, he sent his
respectful compliments to the Admiralty, asking whether they wished the
port or the starboard side of the ship to be painted, for that there was
only enough paint for one half of the ship, and he awaited instructions
as to which side of the vessel it was to be applied. He was impervious
to “minutes,” “directions,” &c., and, as far as I remember, this very
impracticable man got his way, and was supplied with the requisite
amount of paint.
* * * * *
LONG before man ever invented paint or varnish the Hive Bee had made use
of it.
Every one who has kept bees knows how they always fasten the edge of the
hive to the board, and stop up any crevices that may be left open. The
material which they use for this purpose is not wax, but a substance
called “propolis.” This term is composed of two Greek words, signifying
a suburb, or the outskirts of a town, and is given to this stationary
substance in consequence of the use which is made of it.
[Illustration: BEE VARNISHING CELLS.]
[Illustration: PAINTER VARNISHING WOOD.]
Not only do the bees use it for fastening the hives, but also for
strengthening their combs. Wax is a very precious material, and the
beautiful hexagonal structure of the bee-comb is intended for the
purpose of combining the greatest amount of storing space with the least
expenditure of material. The plates of wax of which the cells are
composed are so thin that their edges would break down even under the
feet of the bees as they passed over it, and accordingly the bees
strengthen the edges of the cells with propolis, as any one may see by
examining a piece of bee-comb. The propolis is of a darker colour than
the wax, and has a peculiar varnish-like appearance.
The propolis, as distinguished from wax, is mentioned by Virgil in his
Georgics:--
“Collectumque hæc ipsa ad munera gluten
Et visco et Phrygiæ servant pice lentius Idæ.”--_Georg._ iv. 40.
It is evident that the propolis cannot be obtained from the same source
as the wax. The latter is secreted by the bees under little plates or
flaps upon the abdomen, while the propolis is purely a vegetable
exudation. It is obtained from many trees, the principal being the horse
chestnut. All who have handled the buds of this tree are aware that they
are covered with a viscous and very adhesive matter, which serves as a
varnish or protection to the bud before the leaves are strong enough to
break out. This is the material which the bees gather for their
propolis, and at certain times of the year the chestnuts may be seen
swarming with bees, all busily engaged in scraping off the varnish.
TOOLS.
CHAPTER I.
THE DIGGING-STICK.--SPADE.--SHEARS AND SCISSORS.--CHISEL AND ADZE.--THE
PLANE AND SPOKESHAVE.
The Use of Tools a Distinction between Man and Beast.--All Men,
however savage, use Tools, but none of the lower Animals can do so
until taught by Man.--Tools needed to break up the Ground.--The
Digging-stick of savage Life: its Use and its Efficacy in practised
Hands.--Digging-sticks in Nature.--The Heart-urchin, and its Mode
of digging in the Sand.--The Spade: its Shapes and Uses.--Natural
Spades.--Fore-foot of the Mole and Mole-cricket.--The Aard-vark,
the Ant-eater, and the Mattock.--Shears and Scissors a Sign of
Civilisation, never being employed by Savages.--Mechanical
Principle of Scissors, the Inclined Plane, the Lever, and the
Cutting Edge.--Chinese Shears and the Pruning Scissors.--Use of the
Inclined Plane.--The Diagonal Knife of the Guillotine.--The Shears
in Iron-works.--The “Drawing Cut” of Swordsmen.--Jaws of the Turtle
and Tortoise.--The Snapping Turtle and the Chicken Tortoise.--The
Locust, the Cockchafer Grub, the Great Green Grasshopper, and the
Wart-biter.--The Leaf-cutter Bees and their Nests.--The Chisel and
Adze.--Structure of Rodent Tooth and Chisel.--Use of the hard Plate
of Enamel or Steel.--Combination of hard and soft Materials.--Teeth
of Hippopotamus and Hyrax.--Principle of the Adze.--Self-sharpening
and Self-renewing Tools.--The Plane and Spokeshave.--Principle on
which they are made.--The Spokeshave and its Uses.--The “Guard”
Razor.--The Hoop-shaver Bee and its Nest.--Its natural Plane, and
the Use which is made of it.
Among the many points of distinction between man and the lower animals,
we may consider the use of tools as one of the principal lines of
demarcation. Man stands absolutely alone in this respect. There is no
race of savages, however degraded they may be, that does not employ
tools of some kind, and there is no beast, however intelligent, that
ever used a tool except when instructed by man.
As to the stories that are told of the larger apes using sticks and
stones by way of weapons, they are absolutely without foundation, no
animal employing any tool or weapon save those given to them by Nature.
It is true that a monkey may sometimes be seen to take a stone for the
purpose of cracking nuts which are too strong for its teeth, and to
perform that task with great deftness; but such animals have always been
taught by man, and had they remained in their own country, not one of
them would have used a stone, were the nuts ever so hard.
THE SPADE.
We will begin our notice of tools by taking that which must have been
the first tool invented by man. One of the principal duties assigned to
man is the culture of the earth, and this he cannot do without tools,
increasing their number and improving their structure in proportion to
his own development in agriculture.
Before seed can be sown, it is necessary that the earth should be broken
up, and, owing to the structure of the human frame, this task cannot be
fulfilled by man without a tool which will enable him to rival many of
the lower animals, _i.e._ make use of those digging appliances which
have been furnished by Nature.
[Illustration: HEART-URCHIN. DIGGING-STICK.]
It is evident that the first earth-breaking tool must have been a
pointed stick, and we find that in Southern Africa, in parts of Asia,
and in Australia the Digging-stick is still in use for the purpose of
breaking up the ground. The Australians are wonderful adepts in the use
of the Digging-stick, which is one of the simplest of instruments, being
merely a stick some two feet in length, pointed at one end, and the
point hardened in the fire.
The mode of using it is by holding it perpendicularly, pecking it into
the ground, and throwing out the loosened soil with the hands. In this
way they can excavate with such rapidity, that a strong navvy, armed
with the best spade, would not be able to keep pace with a black man
armed only with his “katta,” or digging-stick.
In Africa the Digging-stick is used in exactly the same manner, and is
generally made more weighty and effective by having a perforated stone
fastened on the handle.
* * * * *
HERE, again, man has been anticipated by Nature, and the savage of
Australia or Africa digs in exactly the same manner as the common
Heart-urchin of our shores, sometimes called the Hairy Urchin, in
consequence of the number and fineness of the spines, which look just
like hairs to the naked eye. The scientific name of this creature is
_Amphidotus cordatus_.
Mr. Gosse, in his “Evenings at the Microscope,” gives so admirable an
account of the mode of digging employed by the Hairy Urchin that I
cannot do better than employ his own words. After describing the variety
of structure of the different spines with which the shell is so thickly
set, he proceeds as follows:--
“But what is the need of so much care being bestowed upon the separate
motion of these thousands of hair-like spines, that each should have a
special structure, with special muscles for its individual movement? The
hairs of our head we cannot move individually: why should the
Heart-urchin move his?”
“Truly, these hairs are the feet with which he moves. The animal
inhabits the sand at the bottom of the sea in our shallow bays, and
burrows in it. By going carefully, with the lens at your eye, over the
shell, you perceive that the spines, though all formed on a common
model, differ considerably in the detail of their form. I have shown you
what may be considered the average shape, but in some, especially the
finer ones that clothe the sides, the club is slender and pointed; in
others, as in those behind the mouth, which are the largest and coarsest
of all, the club is dilated into a long, flat spoon; while in the long,
much-bowed spines, which densely crowd upon the back, the form is almost
uniformly taper throughout, and pointed.”
“The animal sinks into the sand mouth downwards. The hard spoons behind
the mouth come first into requisition, scooping away the sand, each
acting individually, and throwing it outwards. Observe how beautifully
they are arranged for this purpose, diverging from the median line,
with the curve backwards and outwards.
“Similar is the arrangement of the slender side spines; their curve is
still more backwards, the tips arching uniformly outwards. They take,
indeed, exactly the curve which the fore-paws of a mole possess,--only
in a retrograde direction, since the Urchin sinks backwards,--which has
been shown to be so effective for the excavation of the soil, and the
throwing of it outwards.
“Finally, the long spines on the back are suited to reach the sand on
each side, when the creature has descended to its depth, and by their
motion work it in again, covering and concealing the industrious and
effective miner.”
The reader will notice that this mode of digging is exactly like that
which is followed by the users of the Digging-stick, the earth being
first broken up, and the loosened portions thrown aside. The whole of
the description of the spines is exceedingly interesting, but, as it
does not bear directly on the present subject, I cannot admit it into
these pages.
* * * * *
NOW comes another development in digging tools.
We have already seen how effective an instrument a mere piece of stick
can be in the hands of a skilful workman, and the manner in which it can
tear up a given depth of soil. But, for agricultural purposes, something
more is needed, and the ground must not only be broken up, but a certain
regularity must be observed, in order to allow space to be accurately
measured, and the crop apportioned to the area.
Out of the Digging-stick, then, the Spade was developed, its chief
advantage being that it dispensed with the use of the bare hands, and
not only tore up the ground, but threw out the loosened soil.
The reader will remember that in the preceding description of the
Heart-urchin it was mentioned that many of the spines are shaped at
their ends something like spoons, and that their comparatively wide
blades are used in scraping the sand and shovelling it aside. In fact,
these flattened spines are natural spades, used on the same principle as
the modern spade of civilisation.
On the right hand of the illustration are shown two forms of spade, the
one being the ordinary garden tool, and the other a rather curious
implement which is in great use among the metal mines of Cornwall. The
use of the ordinary spade is too familiar to need explanation, and we
come to the Miner’s spade. This implement is used rather as a shovel
than as a spade, the peculiar bend near the blade preventing the foot
from being used as a means of forcing the instrument into the ground. In
fact, it is not meant for the same office as that which pertains to the
ordinary spade, neither can it be handled in the same way.
[Illustration:
FOOT OF AARD-VARK. FOOT OF MOLE-CRICKET. SPADES.
FOOT OF MOLE.]
In Devonshire there is a kind of spade in general use very much
resembling the mining spade, but having a very long handle without any
crutch at the end. The natural consequence of this shape is, that the
spade cannot be used in the ordinary way, neither can it penetrate the
earth to any depth. It can “peel” the ground, so to speak, and can cut
away successive layers of soil. But as for digging “two spits deep,” or
even one spit, the spade would be absolutely incapable of such a task,
no matter how strong might be the hands that wield it. As for the foot,
it may be put out of the question.
* * * * *
WE will now turn to a few examples of spades in the world of Nature.
The lowest figure represents the fore-paw of the Mole, with its
powerful armature of strong and sharp claws, and its broad blade of a
palm. The reader will easily see that in this animal the digging powers
are wonderfully developed. The peculiar form of the fore-foot closely
resembles that of the miner’s spade, while the curvature of the palm
serves, almost without exertion, to throw out the earth which has been
scooped away by the sharp claws.
To watch a Mole burrow is really a curious sight, the only drawback
being that the animal sinks itself so rapidly beneath the earth that a
long inspection is impossible. I have kept several moles for the purpose
of watching their habits, and have always been interested in their mode
of burrowing. I can only define it by using the word “scrabbling.” The
animal scurries and hurries about, seeking for a tolerably soft piece of
ground. When it has found one, it travels no further, but scratches away
with its fore-paws with wonderful power and rapidity, seeming to sink,
as it were, into the earth, rather than to excavate a tunnel.
* * * * *
THERE is an insect well known to entomologists, called the Mole-cricket,
because its structure and many of its habits are strangely similar to
those of the animal from which it derives its name. At the upper part of
the illustration is seen a portion of the fore-foot of the Mole-cricket,
and a better implement of excavation can hardly be imagined.
The reader will probably have noticed that in both these creatures the
spade, if we may so call it, is not a mere flat plate, but is cleft into
several points. It thus answers the purpose of a fork as well as a
spade, the several points serving to break up the soil, and the flat
palm to throw the earth aside.
This principle is carried out even more fully in the fore-paw of the
African Ant-bear, or Aard-vark (_Orycteropus Capensis_), a figure of
which is given in the illustration. This animal is a great excavator,
living in burrows of such dimensions that the wild boar is in the habit
of making its home in them after they are deserted.
Something more, however, than a digging apparatus is needed for the
Ant-bear. This animal feeds almost wholly on the Termites, which it
obtains by tearing down the walls of their dwellings. Now, as these
wonderful buildings are nearly as hard as brick, and, indeed, are
composed of the same materials, it is necessary that the claws of the
Ant-bear should be modified so as to be able to break through the walls.
Accordingly, they are much more curved than those of the Mole and the
Mole-cricket, and so serve for tearing as well as digging, being struck
into the wall, and thus pulling it down, just as a labourer breaks down
a bank with his mattock.
Indeed, had we wished to extend these analogies still further, we might
easily have given the claws of the Aard-vark as a prototype of our
English mattock. The same weapons as possessed by the Ant-bear of
tropical America are used in exactly the same manner, but are even
stronger, and extend to such a length that when the animal walks, it
cannot stretch its claws out in front, but is obliged to double them
under its feet.
SHEARS AND SCISSORS.
These instruments are sure signs of civilisation, no savage nations
having the least idea of them. Even the Kafir and Esquimaux tribes,
which are such admirable workers in skin, never use scissors in shaping
their garments, but invariably employ knives for that purpose. The
Chinese, however, seem to have known scissors from time immemorial, and
to have shaped them almost exactly like our own instruments. I possess
one pair of tailor’s shears from China in which there is only one ring,
namely, that for the thumb. The place of the other ring is taken by an
elongated, slightly curved and moderately pointed rod of steel, which is
used for tracing the pattern on the material preparatory to cutting it.
Simple as the scissors may seem, they combine several very important
principles, namely, the inclined plane, the lever, and the cutting edge.
Were they to be merely two edges moving directly upon each other, their
effect would be comparatively slight; but, owing to the manner in which
the blades are fixed at one end, they are drawn as it were over the
object between them, and so divide it with comparative ease. In some
instruments, such as the pruning scissors, there is only one cutting
blade, the other being used merely as a support for the branch which is
being cut.
A well-known example of a single cutting blade is found in the
guillotine. In the earliest times of this invention an ordinary axe-head
was suspended above the neck of the criminal. It was found, however,
that its operation was very uncertain, simply because the blow was a
direct one, and not oblique. The blade was then set obliquely, as in the
present machine, and its effect was absolutely certain.
Perhaps some of my readers may be swordsmen, and therefore know the
power of the “drawing cut,” by which a great effect may be produced with
very little apparent exertion. Even in the simple operation of cutting
bread we always use the knife diagonally, though perhaps we may be
ignorant of the principle of the inclined plane.
Next comes the principle of the lever, as exemplified by the handles of
the scissors. By lengthening these handles, the power of the blades is
enormously increased, as may be seen in the various shears in any great
iron-works, which cut through thick iron as if it were butter. Our own
garden shears for trimming borders show very well the power of the long
arms and short blade.
* * * * *
IN the animal world we find many examples of natural shears, one of the
best of which is afforded by the jaws of the Tortoise or Turtle. Owing
to the manner in which they feed, whether they be vegetarians or
carnivorous, their jaws are made for cutting, and not for lacerating or
mastication. They have no teeth, but each jaw is furnished with a horny
edge, as sharp as a knife-blade, and very strongly made. With these jaws
the animal can shred to pieces the objects which it attacks, just as if
it had been furnished with a pair of veritable shears. Any one who has
possessed an ordinary Tortoise must have noticed the havoc which it will
occasionally make in a garden. I had one of these reptiles for some
years, and was obliged to keep it under restraint, in consequence of the
power of its jaws.
Being a Tortoise of discrimination, it took a great fancy to the
strawberry beds, and invariably picked out the ripest and best-flavoured
fruit. Reversing the usual proverb of making two bites at a cherry, the
Tortoise always took two bites at a strawberry, and sometimes three or
four, according to its size.
At last, I was obliged to restrain it by boring a hole in the edge of
its shell, passing one end of a string through it, and fastening the
other to a peg driven into the ground. At first, I tied the string to a
brick, but the Tortoise was so strong that it dragged the brick about
the garden, leaving reminiscences of its progress in the channels which
it had cut through all kinds of vegetation with its scissor-like jaws.
[Illustration: JAWS OF TURTLE.]
[Illustration: SHEARS.]
The reader, in comparing the illustration of the Turtle-jaws with that
of the Shears, will see at once how exact is the analogy between the
two. The sharp-edged jaws correspond with the blades of the shears, the
joint at the skull corresponds with the pivot of the shears, and the
muscles which move the jaws, but which could not be shown in the present
illustration, are the prototypes of the handles.
In some of these creatures, especially those which are carnivorous, the
power of the jaw is tremendous. One of them, a Snapping Turtle, has been
known to bite off several fingers of a man’s hand as easily as if they
had been carrots. Some years ago I kept some Chicken Tortoises alive,
and was much struck with the enormous proportionate power of their jaws.
They were quite little creatures, only a few inches in length, but their
appetites were astonishing, and their mode of satisfying their hunger
remarkable. They were always ravenous after meat, and had a curious way
of seizing their food in their mouths, placing one paw on either side of
their jaws, and then pushing the meat forcibly away, so as to cut out a
slice as large as their jaws.
They were very good-tempered little things, but, small though they were,
I should have been very sorry to have one of them take a bite at my
finger by mistake.
Knowing their general characteristics, I took care not to have any
living creature in the same vessel. But I have heard, from those who
have had practical experience, that Chicken Tortoises ought to be
banished from any place wherein fish are kept, especially if they be
gold fish, the Tortoise having a way of coming quietly beneath them,
biting out a mouthful of their bodies, and then disappearing with its
booty.
* * * * *
BESIDE the Tortoise, there are many creatures which possess natural
shears, such as the Locust, whose ravages are only too notorious. Then,
taking our own country, we have plenty of examples of insect shears.
Such is to be found in the jaws of the Cockchafer larva, or “White Grub”
as it is popularly called. It lives underground, and feeds chiefly on
the roots of herbage, shredding them to pieces with its shear-like jaws.
And, as it spends on the average three years in the one task of
perpetual eating, the damage which it does can be easily imagined.
There is a very pretty English insect which admirably exemplifies the
power of the natural scissors. This is the Great Green Grasshopper
(_Acrida viridissima_), which is equally voracious in all its stages of
existence. It is always ready to use these jaws, and I do not recommend
the reader to allow his finger to get between them, or their points will
probably meet.
One of these insects, indeed (_Decticus griseus_), has derived the name
of Wart-biter from its supposed use in curing warts. All that was
needful was to catch a Wart-biter, and hold one of the warts to its
jaws. It was sure to seize the wart, and bite it smartly, and there was
a firm belief that any one thus bitten would be freed from the unsightly
excrescence. The bite of the shear-like jaws caused much pain at the
time, and this very pain had in all probability something to do with the
cure.
* * * * *
AN admirable example of the insect jaws used as scissors is to be found
in the well-known Leaf-cutter Bees, insects belonging to the genus
Megachile.
They make their nests in burrows, sometimes in wood, and sometimes in
the ground, and form them in a very singular manner. After fixing upon a
suitable burrow, the Bee goes off to a tree, generally a rose, and,
using her jaws just as a tailor uses his shears, cuts off a nearly
semicircular piece of leaf, flies away with it to her home, and, by dint
of bending, pushing, and pulling it, she forces it to the bottom of the
cell. Successive pieces of leaf follow, until she has made a
thimble-shaped cell, and she then places at its end an egg and a supply
of honey and pollen.
Cell after cell succeeds, each being introduced into its predecessor
just as thimbles are packed. Judging from a specimen in my collection,
there are about eight layers of leaves to form the walls of the cell,
and the average length of each piece of leaf rather exceeds half an
inch. The entire length of the cell-group is two inches and a half. The
leaf-slices are always cut from the edge, and, in my specimen of the
nest, the serrated outer edges of the leaves are all in one direction.
Should any of my readers find one of these nests, it will be as well for
them to dip a needle point into diamond cement, and introduce it under
the outermost coating of leaves. Otherwise, when the leaves are dry, and
the insects break their way into the open air, the cells will probably
fall to pieces.
These Bees are much more abundant than is usually thought. In
summer-time it is hardly possible to find a rose-bush on which are not a
number of leaves from which pieces of variable size and shape, but
always with a curved outline, have been cut as with scissors. While
cutting them, the Bee seems to trace out her pattern, as it were, by
using her feet like one leg of a pair of compasses, and her head as the
other leg. As soon as she has nearly finished the operation, she poises
herself on the wing, to prevent her weight from tearing away the leaf
irregularly, and then, while still on the wing, makes the last few
bites, and severs the leaf entirely.
THE CHISEL AND THE ADZE.
Already we have seen how exact is the analogy between the scissors and
the turtle-jaw. As we are upon the subject of cutting instruments, we
will continue it, trying to discover some further analogies.
On the right hand of the illustrations we see three cutting tools made
by human hands--_i.e._ the Chisel, the Stone Adze of Polynesia, and the
Steel Adze of this country. We begin with the Chisel.
All those who have even a slight knowledge of anatomy know how curiously
exact is the resemblance of the Chisel of civilised life to the front
tooth of any Rodent animal. The head of the Beaver is here given as an
example, but the tooth of a mouse, rat, or rabbit, which can easily be
obtained, is quite as good an example. These teeth are made after a very
beautiful fashion. Their outer surface is covered with a plate of very
hard enamel, while the rest of the tooth is of bony matter, and
comparatively soft. Consequently, when the tooth is used, the enamel
plate forms a sharp edge, while the rest of it is worn away, thus
keeping the chisel-like end in its proper form.
[Illustration: TOOTH AND JAWS OF BEAVER.]
[Illustration: CHISEL.]
The power of these teeth may be appreciated by any one who has been
bitten even by so small a rodent as a mouse, the sharp edges meeting in
the flesh, and causing a very painful wound. When the teeth are large,
as in the Beaver, and the jaws powerful, their force is something
wonderful, tree-trunks of considerable size being cut down quite easily.
Perhaps some of my readers may not be aware that the Chisel is
constructed on exactly the same principle as the tooth of the Rodent
animal. It is not entirely made of steel, as is generally thought. In
the first place, a valuable material would be needlessly wasted, and, in
the next place, the tool would not keep its edge except with infinite
labour in grinding.
The principal part of the Chisel-blade is therefore made of soft iron, a
very thin plate of steel running along the back. This plate answers the
same purpose as the enamel in the tooth, while the soft iron takes the
place of the soft bone. Axe-blades, which are, in fact, formed like two
chisels placed back to back, are made on a similar principle, except
that the steel plate occupies the centre of the blade, and the soft
iron is on either side. Thus the thin plate of steel is easily brought
to an edge, while the soft iron can be ground away without any
difficulty.
I do not mean to state that the inventor of this combination of thin
steel and soft iron had taken his idea from the Rodent tooth, but only
to show that the invention, beautiful, simple, and ingenious as it is,
has its prototype in Nature. I may here mention that the Plane-iron,
which is, in fact, a modified Chisel, is made in exactly the same
fashion.
* * * * *
NEXT we come to the Adze.
[Illustration: ADZE-TEETH OF HIPPOPOTAMUS.]
[Illustration: STONE ADZE OF POLYNESIA. STEEL ADZE.]
In some respects there is much resemblance between the blade of the Adze
and the teeth of the Rodent, especially in their curve, which is almost
identical in both. This form is seen in the structure of other teeth
than those of Rodents. There is, for example, the tooth of the
Hippopotamus, which is not only curved, like that of the Rodent, but
bevelled off in a similar way at the tip. With these formidable teeth,
one of which is now before me, the Hippopotamus makes terrible havoc
among the herbage, mowing it down, so to speak, and stowing it away
wholesale in its enormous stomach. A Hippopotamus indeed, when angered,
has been known to sever a man’s body completely in two with a single
bite, so trenchant are the teeth, and so powerful the jaws.
Then there is a little animal called the Hyrax, or Rock-rabbit, which is
the coney of Scripture. This creature is really one of the
pachydermatous group, although its small size, hairy coat, its activity
among the rocks, and its apparently rodent teeth, have induced many
persons to place it among that group. These teeth, however, like those
of the Hippopotamus, are bevelled off at their tips, and, as they
perform a similar office, they take a similar curve.
It is worthy of notice that in the Stone Adze the bevelled edge much
more resembles the rodent tooth than does the Steel Adze, the reason
being evidently that stone is more fragile than steel, and requires
greater thickness. Still, the principle is the same in both, only the
metal is more attenuated than the stone.
The Rodent or Hippopotamus tooth has still a great advantage over any
chisel or adze made by man, whether of stone or metal. As our tools are
blunted, we are forced to spend much time in sharpening them, and by
degrees grind the tool away until it becomes useless. Now, the teeth are
so arranged that their perpetual use, instead of blunting, only sharpens
them, and in proportion as they are worn away in front they are supplied
with fresh matter from behind, and perpetually pushed forwards, so that
they are self-renewing as well as self-sharpening.
THE PLANE AND SPOKESHAVE.
I have already made mention of the Plane in connection with the Chisel,
and shown that, like that tool, it is formed on the same principle as
the Rodent tooth.
The use of this important instrument in carpentering cannot be
overrated, as is shown by the numberless varieties which are used by
carpenters, and the different uses to which they are put, sometimes
merely smoothing a level surface, and sometimes forming a “moulding”
where ornament is required.
In principle, a Plane is a cutting edge or chisel, pushed along the
object to be worked, and, the edge being guarded, taking off a very thin
shaving from the surface.
On the right hand of the accompanying illustration is shown the Plane in
action, with the thin shavings falling from it in curled masses. Perhaps
some of my readers may have visited some of the great iron-works, and
been struck with the use of the Plane as applied to metal instead of
wood, long iron shavings being taken off as easily as if they were
deal, and curling in just the same manner.
* * * * *
THERE is an instrument very familiar to carpenters, called the
Spokeshave, on account of its use in trimming the spokes of wheels.
Different as it may be in appearance, it is identical in principle with
the plane, having an edge guarded by a piece of wood, so that the blade
cannot cut too deeply into the object on which it is employed. The chief
distinction, indeed, is, that the workman, instead of pushing the blade
from him, draws it to him.
[Illustration: HOOP-SHAVER BEE.]
[Illustration: PLANE. SPOKESHAVE.]
When shaving was more in fashion than it is in these more sensible days,
there were many inventions to lessen the trouble, not to say the perils,
of shaving. To use the razor in a hurry was anything but an agreeable
occupation, especially if the weather were frosty, and the fingers so
chilled that they hardly knew whether or not they had the razor between
them.
In order to render this very unpleasant task less disagreeable, some
ingenious individual invented the Guard Razor. The principal part of the
invention consisted in a plate of metal sufficiently thin not to add
materially to the weight of the razor, and sufficiently strong to resist
a moderate amount of pressure. This was fixed along the blade of the
razor in such a way that it just allowed the edge to show itself, and,
in fact, converted the razor into a plane or spokeshave. The exact
amount of edge which might be shown was regulated by screws, and the
guard itself could be removed at pleasure, so as to allow of the razor
being sharpened.
Now let us see if we can find any examples of the Plane or Spokeshave in
Nature.
* * * * *
I TRACE at least one example of the Plane in the insect world. More than
a hundred years ago, that very observant naturalist, Gilbert White,
noticed a bee performing a curious task. She was running up the stem of
the garden campion, holding her jaws extended, and stripping off the
down with all the dexterity of a hoop-shaver. She collected a bundle
nearly as large as herself, and then flew away with it. What she did
with her burden he knew not, but the history of the insect has been told
fully, though briefly, by Mr. F. Smith, in his “Catalogue of British
Hymenoptera:”--
“Although the species belonging to this genus are numerous, and are
found both in the Old and New World, there is only one found in this
country, _Anthidium manicatum_; this is truly a summer bee, not making
its appearance before the latter part of June or beginning of July.
“This insect, so far as my own observation has enabled me to ascertain,
does not construct its own burrow, but makes use of any hole which is
adapted to its purpose. I once detected a bee entering the hole above
the wheel of the sash-line in a summer-house; but its nests are most
commonly formed in the holes bored in old willow stumps by _Cossus
ligniperda_ (the Goat-moth): formerly they were easily obtained in
Battersea Fields, where the willows abounded.
“It is probable that when the parent insect has selected one of these
ready-formed tunnels, she enlarges the end used as the depository of the
nest, and this is easily effected, as the stumps in question, at the
depth of a couple of inches, consist of soft decayed wood.
“The chamber being formed, the bee collects a quantity of down from
woolly-stemmed plants, with which she forms an outer coating. She then
constructs a number of cells for the reception of the pollen, or food of
the larva; they consist of a woolly material, mixed with some glutinous
matter which resists the moisture of the food they contain, and in
which the larva, being full fed, spins a brown silken cocoon. These bees
pass the winter in a larva state, and do not appear until midsummer.
“In one respect, the sexes of this genus differ from most other bees,
the males being much larger than the females.”
The reader will see from this account how exact is the analogy between
the carpenter’s plane and the jaws of the bee. In consequence of the
simile employed by Mr. White, the insect has been popularly known by the
title of the Hoop-shaver Bee. It is a tolerably common insect, and
abounds in the South of England.
TOOLS.
CHAPTER II.
THE SAW AND ITS VARIETIES.
Cutting Tools and their working.--Structure of the Edge.--The
Kris.--Edge of a Razor.--The Sword and the Apple.--Australian
Saw.--Fretwork Saw.--Various Saw-flies.--The Pioneer’s
Saw.--Cutting Tools of Trichiosoma.--Side Teeth of the Saws.--The
Cordon Saw, or Band Saw.--Tooth-ribbon of Whelks, Slugs, and other
Molluscs.--The Dog-whelk, or Purpura.--The Circular
Saw.--Sawyer-beetles and their Mode of Work.
Still keeping to the Cutting Tools and their varieties, we come to the
Saw, _i.e._ the cutting tool set with teeth upon its edge. Now, in plain
fact, there is no cutting instrument that does not more or less partake
of the character of the Saw; for, in the first place, it is absolutely
impossible for man to grind an edge so fine that, when magnified, it
will not appear to be deeply notched, and, in the next place, its
cutting powers are greatly due to the notches and teeth, and the
direction of their points.
We will take both these subjects in turn.
First, as to the notches, or serrated edge. I have now before me two
instruments, each the best of their kind, and in both of which the
serrations are essential to efficacy. The first is a Malayan dagger, or
“kris,” and the second is a surgeon’s lancet, made by Ferguson, of
London.
In the kris the edge is intentionally serrated, having been eaten away
by means of acids until the required effect was produced. The Malayans
know by experience that such an edge is most deadly in a weapon, and
that it will cut certain vital parts which a smoother edge might pass
without doing any damage.
Now we will take the lancet, and put it under the microscope, when it
assumes the most curious resemblance to the kris. Its mirror-like
surface looks as if it had been very roughly treated with a coarse file,
while its thin and delicate edge, which is perfectly smooth to the eye,
and which will pass through a piece of stretched wash-leather without
any apparent opposition, becomes as rough and jagged as that of the
Malayan weapon.
Take even, for example, the common butcher’s knife, which is perpetually
being sharpened on the “steel” that hangs at his belt. The reader may
observe that the butcher does not rub the blade of his knife backwards
and forwards on the steel, as unskilful persons do. Rapid as is the
movement gained by constant practice, any one may see that the blade is
always moved in one direction, so as to force the microscopical teeth to
point one way, and so to act as a saw when the knife is drawn across the
meat.
The power of these teeth or notches may be inferred from a well-known
fact. If a razor, no matter how sharp, be pressed upon the human skin
without any “draw,” it will indent the skin, but not cut it, while the
slightest drawing movement will cause a deep wound. It is the knowledge
of this fact that enables an expert swordsman to sever an apple placed
on the palm of the bare hand, without even scratching the skin. I have
witnessed this feat, and at once saw that it was due to the absence of
any “draw” to the cut. The apple was laid on the palm of the hand, which
was opened as widely as possible, so as to flatten it. The sword was
then brought down on the apple with a sort of chopping movement, so
that, although it indented the skin, it did not even inflict a scratch.
By the use of the “drawing” movement, the same sword severed a gauze
veil laid across it, the two halves floating in opposite directions. By
the same cut, I have seen some astonishing feats performed with an
Indian sword now in my collection, the objects of attack falling asunder
as if by magic, without any apparent force being used.
* * * * *
HAVING now glanced at the principle of the Saw, we will proceed to some
of its details.
The simplest form of Saw in existence is that which is in use among the
Australian natives, and consists of obsidian flakes set along one side
of a stick. It looks a rude and inefficient affair enough, but it can
cut better than might have been thought, as I can testify from
experiments on such a saw in my collection.
[Illustration: SAW OF COMMON SAW-FLY (MAGNIFIED). GROOVES CUT BY SAW IN
BARK.]
[Illustration: HAND-SAW. TENON SAW. PIONEER’S SAW-SWORD.]
Many as are the varieties of the Saw, the principle is the same in all,
and the chief distinction lies in the shape and arrangement of the
teeth, according to the work which they have to do. Watch-spring Saws,
for example, which have to cut metal, have their teeth so slight as to
be hardly perceptible, and arranged nearly in a line with each other.
The Fretwork Saws, which have to cut delicate patterns in wood, with the
slightest possible waste of material, are of the same character. Then we
have the long curved teeth of the Circular Saws, which tear their way
savagely through great tree-trunks, and fill the air with clouds of
sawdust. There are also the Tenon Saw, with its thin blade and broad
back; the pioneer’s saw for cutting green wood, with its double array of
teeth, so as to make a wide “kerf” in which it shall not be clogged;
together with many others that we cannot enumerate here.
* * * * *
WE will now examine some Saws as found in Nature.
I need scarcely say that some of the best examples of natural saws are
furnished by those insects which are known to entomologists as
Tenthredinidæ, and to the general world as Saw-flies. These insects are
supplied by Nature with a pair of most remarkable saws, which aid them
in depositing their eggs. Indeed, without these instruments, the whole
race of Saw-flies would long ago have become extinct.
They haunt almost every kind of tree and many plants, and one valuable
plant, the Turnip, is so devastated by them, that whole crops are
sometimes swept away. As, therefore, the knowledge of the life-history
of any insect will tell us whether to protect or destroy it, and the
best method of adopting either course, we will cast a hasty glance at
some of our commonest Saw-flies, the instruments which they employ, the
mode in which they use them, and the analogies between them and the saws
made by the hand of man.
In the first place, it must be observed that the use of these saws is to
cut grooves in young bark, these grooves being the depositories of their
eggs. It follows, therefore, that as a tolerably wide groove is needed,
the saw-blade is a tolerably thick one, and the teeth set on the same
principle as that which is employed in the saw-sword of the pioneer.
When the microscope is applied to the cutting instrument of the Saw-fly,
it reveals the fact that there are two horny saws, which work
alternately in their grooves, and that they are strengthened by a thick
plate of horn on their backs.
The system of toothing is very complicated. Not only are the sides as
well as the edges of the saws toothed, but each tooth is furnished with
smaller teeth, after the fashion of the shark’s wonderfully effective
cutting apparatus. These subsidiary teeth vary greatly in shape and size
according to the species, and in some cases each tooth is quite a
complicated structure. In _Trichiosoma lucorum_, for example, a bee-like
insect, very common upon hawthorn, the teeth are extremely beautiful. It
is difficult to describe them without diagrams, but I will try to give
the reader an idea of them.
Each tooth is somewhat of a lancet shape, but is not terminated by a
single point. At the tip comes the secondary tooth, which is conical and
stands on a footstalk. The cone, however, is not simple, but is made of
some seven or eight cutting plates, each smaller than its predecessor,
and the last being a sharp conical point. The reader may imagine how
effective such a saw would be in cutting green wood, the toothed sides
and the subsidiary teeth alike preventing the blades from clogging,
while the alternate movement of the saws enables them to do double work
in the same time.
Mr. Westwood, who examined these insects very closely, throws out, in
his “Modern Classification of Insects,” the idea which forms the subject
of this book. Writing of the cutting weapon of the Saw-flies, he remarks
that “from its admirable construction it cannot be doubted that a
careful examination of its various modifications might furnish ideas for
improved mechanical instruments.”
Mr. Gosse, in his “Evenings at the Microscope,” points out that,
beautiful and elaborate as these instruments are, they are but the
sheaths of a still finer and more delicate pair of saws. These secondary
saws have only a few teeth on the edge, and these near the point,
whereas the sides are furnished with a number of sharp blades, set on
their edges, slightly overlapping each other, and directed backwards.
There is a similar structure on the ovipositor of the Sirex, as we shall
see when we come to treat of Boring Instruments.
Although the saws are made expressly so that they shall not stick in the
wood, there are many instances known where female Saw-flies have been
found dead on the branches, their saws still in the last groove which
they have cut. I am inclined to think that these must be females which
have deposited all their eggs, and which have died, as do nearly all
insects under similar circumstances. This opinion is strengthened by
some observations made by Mr. J. K. Lord on the Cicada, the female of
which is furnished with a similar ovipositor:--
“I was curious to watch the female depositing her eggs.
“She first clasps the branch on both sides with her legs, and with the
ends of the file very carefully slits up the bark. Then, placing the
instrument longitudinally, she files away until she has obtained
sufficient length and breadth. The _small_ teeth of the files are now
used crosswise of this fissure, until a trench is made in the soft pith.
“When large enough, slowly down the groove in the centre of the
instrument glides a small pearly egg, pointed at both ends, and so
transparent that the little grub within is clearly discernible. Gently
she lays it within its bed, and then drops a thin gummy material on it,
to secure it from moisture. This finished, she proceeds to deposit
another, and so on, until a sufficient number are produced to fill the
fissure; then over all she drags the everted bark. It is easy to
perceive where the Cicada has been concealing her brood, by the
elevation on the branch.
“In this manner she deposits about seven hundred eggs, going from branch
to branch, her marvellous instinct teaching her to select the most
suitable wood for the purpose. The time occupied in constructing each
nest was from fifteen to twenty minutes. Her earthly mission finished,
she drops, fainting and exhausted, from the branch, and dies.
“The male, who is always trilling his refrain, goes on, indifferent, or
unconscious, that the task of his faithful spouse is finished, singing
even, until his time comes--then he too drops beside her. Thus the songs
one by one cease,--not only the Cicada’s, but all the forest choir, and
give place to blasts that sigh in mournful music through the leafless
trees.”
The Sirex and several of the larger Ichneumon-flies are often found dead
in like manner, and I have no doubt from the same cause. An elaborate
description of the beautiful double saws of the Cicada is given by Mr.
Westwood in the work already quoted, together with illustrations.
THE RIBBON SAW, CORDON OR BAND SAW.
Perhaps some of my readers may be acquainted with a saw which has of
late years come into extensive use--namely, the Ribbon Saw, Cordon Saw,
or Band Saw. This is an endless steel band toothed on one edge, and
passing over two wheels. It has the advantage of being of almost any
breadth, some being several inches wide, while others are mere narrow
ribbons, barely the sixth of an inch wide. The fretwork of pianos and
other articles of furniture is cut almost exclusively by the Cordon Saw.
A thick piece of wood is cut of the requisite shape, and the upper and
under surfaces planed quite true to each other. The pattern is traced on
the upper surface, and a very narrow Cordon Saw is then applied to it,
cutting completely through the thick block, and adapting itself to all
the intricacies of the pattern. The block is then cut into thin slices,
so that a number of pieces of fretwork can be made with comparative
ease. To those who have been accustomed to cutting fretwork with the
slow hand-saw, the Cordon Saw is simply fascinating, the slender steel
ribbon cutting through the wood with wonderful rapidity and very little
sound.
* * * * *
BEAUTIFUL as this invention is, it was long ago anticipated in Nature;
and the Cordon Saws, which we shall now see, are armed with teeth many
more in number, and far more complicated in detail, than those of any
saw made by the hand of man. I allude to the Tooth-ribbon possessed by
many of our common molluscs, such as the Limpet, the Whelk, the
Periwinkle, the Slug, &c. The last mentioned of these creatures
possesses a natural Cordon Saw with nearly twenty-seven thousand teeth,
and scarcely a tooth that is not elaborately cut into secondary teeth.
[Illustration: PORTION OF TOOTH-RIBBON OF WHELK (HIGHLY MAGNIFIED).]
[Illustration: RIBBON OR CORDON SAW.]
As all these creatures have their teeth differently formed and set,
according to the species, it will be impossible to describe them
separately. I will therefore restrict myself to the Tooth-ribbon of the
common Whelk, a specimen of which is now before me. When viewed through
the microscope, it is found to consist of a flat membranous ribbon, on
which are set three rows of teeth, those of the outer row being hooked,
and those of the inner one plain.
The outer teeth are formed somewhat like the Hebrew letter כ, both of
the points being very sharp, and the central part being furnished with
two secondary teeth. All these teeth overlap each other, so that some
care in manipulation is required before their form can be made out.
Along the centre of the tooth-ribbon run successive rows of small,
lancet-shaped teeth, six in a row, so that altogether there are eight
teeth in each row.
The power of this weapon is astonishing. Some of my readers may be aware
that Whelks are carnivorous beings, and that they swarm upon any dead
animal which may be found in the sea. Indeed, when we hear of the
mutilations which take place on dead corpses after a shipwreck, and
which are generally attributed to fishes, we may make up our minds that
the real delinquents are the Whelks, together with various crustacea,
and that the principal instrument in effecting such mutilation is the
tooth-ribbon which has just been described.
The Whelks feed largely upon other molluscs, in spite of their shells. A
periwinkle has a peculiarly hard shell, and yet Mr. Rymer Jones saw a
Dog-whelk (_Purpura lapillus_) eat a periwinkle in a single afternoon,
first boring a hole through its shell with the tooth-ribbon, and then,
by means of the same weapon, licking it, so to speak, out of its shell.
The Periwinkle itself has a similar tooth-ribbon, and so have the Limpet
and the pretty Top-shell. These creatures are vegetarians, but they are
furnished with similarly armed tongues, and use them in the same way.
Nothing is easier than to see these tooth-ribbons in use. When sea-water
is kept in glass vessels, a green flocculence is sure to collect upon
the glass and to render it opaque.
If, however, a few Periwinkles and Top-shells are placed in the tank,
they immediately set to work at this confervoid growth, and by means of
the tooth-ribbon sweep off the green substance, leaving the glass nearly
clean. This movement can be seen with the naked eye, but with the
assistance of a pocket lens the action of the tooth-ribbon is
beautifully shown as it issues from its socket, makes its sweeping
curve, with the tiny teeth glittering like specks of glass, and then is
withdrawn ready for another sweep.
Should sea-water and living Periwinkles not be easily obtained, the same
phenomenon may be observed in fresh water, and with the common
Pond-snail, which may be caught by thousands in any stream and in most
ponds.
THE CIRCULAR SAW.
In one sense the Cordon Saw is a Circular Saw, but we now restrict the
name to the tool which has a circular blade, more or less deeply toothed
on the edge. The largest and coarsest of these saws are of enormous
diameter, have teeth several inches in length, and can cut a large
tree-trunk asunder in a wonderfully short time.
There is a huge saw of this kind in Chatham Dockyard. It is kept in a
sort of cellar covered with flap doors, where it really has the air of
some dread monster lying in wait for prey. A tree-trunk is brought for
it to feed upon. The doors slowly open, the saw emerges, revolves so
fast that the eye cannot detect the teeth, seizes on the tree-trunk,
tears its way through with a scream and roar, and then sinks back into
its cellar. I have often watched this saw in action, and have never been
able to get over a kind of feeling that it was alive.
[Illustration: SAWYER-BEETLE.]
[Illustration: CIRCULAR SAW.]
Now, if we suppose the saw to be pierced in the centre, and to have
teeth on the inside instead of the outside, it would be equally
efficacious; and, indeed, we have several tools used for cutting iron
bars or pipes, that are constructed on a similar principle, though the
cutting tooth revolves slowly instead of rapidly, and is urged by a
lever handle.
* * * * *
THERE is in Nature a Circular Saw of just such a character, the teeth
having their points directed inwards, and not outwards.
In tropical America there are several large beetles which, like our
Stag-beetle, feed upon the sap of trees, and obtain it by wounding the
young branches with their jaws.
One or two of them are pointed out as having the power of cutting a
branch completely off by seizing it in their deeply toothed jaws, and
flying round and round the branch so as to convert themselves into a
circular saw. The late Mr. Waterton showed me a branch which had fallen
on his head, and which was said to have been cut off by the
Sawyer-beetle, as the insect is called. He did not actually see the
insect at work, but he had no doubt that the natives were right who told
him that it was the work of beetles’ jaws. Certainly the cut looked
exactly as if it had been made in the way described. The branch was
somewhat thicker than an ordinary walking-stick.
The truth of this statement has often been denied, but I have
ascertained from personal observers that it is literally true. A loud
noise is produced by the operation, and, as the female is never seen to
perform it, the general idea is that it is a call to its mate.
TOOLS.
CHAPTER III.
BORING TOOLS.--STRIKING TOOLS.--GRASPING TOOLS.
The Bradawl and the Gimlet defined.--Natural Bradawls.--The
Ichneumon-flies.--A Pimpla engaged in Boring Operations.--Principle
of the Wedge.--Resisting Power of Earth.--Pitching Tents in
Sand.--Hidden Forces of Nature.--The Aloe-leaf and its Growth.--A
cruel Punishment.--Natural Gimlets.--Ovipositor of the Sirex, and
its Analogy to a Carpenter’s Gimlet.--The Auger and the
Gad-fly.--Striking Tools.--The Hammer.--Origin and Development of
the Tool.--The Axe.--The Woodpecker and the Nuthatch.--The
Ivory-billed Woodpecker.--Grasping Tools.--Pincers and their
Modifications.--Sugar-tongs and Coal-tongs.--Natural
Pincers.--Bivalve Molluscs.--The Clam’s Grip.--The Earwig.--Crab
and Lobster Claws.
BORING TOOLS.
Next in importance to the edged tools which cut, come the pointed tools
by which holes can be bored. We have an abundance of such tools, but
they can all be reduced to two types, namely, those which, like the
Bradawl, are forced between the fibres, and those which, like the
Gimlet, cut away the material as they pass through it.
They may, again, be shown to be different modifications of a single
principle--_i.e._ that of the Wedge or Inclined Plane, which, as has
already been shown, is identical with that of the screw. The Bradawl is,
in fact, a sharp wedge, which is forced through the fibres, sometimes
being merely forced between them, and sometimes cutting them, and thus
forcing aside the severed fibres.
A natural example of the Bradawl is to be found in various
Ichneumon-flies, especially those with very long ovipositors, which are
intended for boring into wood.
All the Ichneumons are parasitic, laying their eggs in the larvæ of
other insects, mostly those of moths and butterflies. Generally these
larvæ exist in the open air, and the Ichneumon-fly has little difficulty
in piercing them. But there are some which live either in wood or
underground, and, in order to reach their hidden bodies, the Ichneumon
is furnished with an extremely long and sharply pointed ovipositor.
This wonderful instrument is not so thick as an ordinary horsehair,
although it is composed of three portions, and seems to be utterly
inadequate to the task which it has to perform. Ascertaining by its
instinct the exact locality of the caterpillar which it desires to
pierce, the Ichneumon-fly clings firmly to the tree, bends the body so
as to bring the point of the ovipositor against the wood, and, by moving
the abdomen backwards and forwards, gradually works the instrument into
the wood, sometimes piercing it to a considerable depth.
Mr. Westwood once saw an Ichneumon-fly thus boring its way into a dry
post, the wood of which must have been very hard. When she had bored far
enough, she partially withdrew the ovipositor, and then re-plunged it
into the hole that she had made, as if she were depositing eggs. While
engaged in this operation, she stood very high on her long legs, resting
only on the extremities of the feet. She belonged to the genus Pimpla.
* * * * *
THE principle of the Wedge or Inclined Plane is admirably shown by
objects which we pass unheeded every day, and yet afford wonderful
examples of the power of the wedge.
Scarcely any vegetable growth is so plentiful as grass, which has been
used in that sense by the highest of all authorities, “which to-day is,
and to-morrow is cast into the oven.” Grass forces its way
everywhere--not only in cultivated grounds, but in the wildest of lands,
where there is scarcely any nurture for it. Even among the habitations
of mankind the grass will have its way, and clothes deserted housetops
with verdure, and forces itself between the stones that pave neglected
streets.
Place side by side some of these stones, together with a very young and
tender Grass-blade, and it will seem to be impossible that so fragile an
object should be able to exert any influence on the solid stone. Let any
one try to push a sharp skewer between the stones, and he will find that
he has to exert power sufficient to crush a thousand grass-blades. Yet
these slight and delicate objects will force themselves between the
stones, and sometimes to such an extent as to cover the whole roadway
with verdure.
The force which is employed is simply marvellous, and can only be
appreciated by those who know the resisting power of earth, however dry
and loose it may be. Even sand has so strong a resistance that tents can
be pitched in the desert without difficulty. Of course the ordinary
tent-peg would be useless, but the desert dwellers can pitch their tents
with perfect security. They fasten the tent-rope to a branch or piece of
bush, scrape a hole in the sand, put the bush into the hole, cover it up
again, and it will withstand almost any strain, though it be only
covered with a few inches of sand.
[Illustration: GRASS-BLADES.]
[Illustration: WEDGE.]
When miners blast rocks with gunpowder, they take advantage of the
resisting power of sand. They bore a suitable hole, place a charge of
gunpowder at the bottom, and then merely pour loose sand into the hole
until it is filled. When the powder explodes, the rock or coal is
shattered to pieces, but the sand is not blown out of the hole. This
operation is called “tamping.”
Every one, again, knows how firm are gate-posts, and how they resist the
weight, jarring, and leverage of a heavy gate, all because they are sunk
a little way into the earth.
Considering, therefore, that such fragile things as young grass-blades
can force their way through the superincumbent weight, we can but be
amazed at the aggregate of active force which is in full operation in
every pasture field and garden lawn.
As far as I know, not being much of a botanist, every seed that springs
up does so on the wedge principle, though the form of the wedge may be
varied.
A terrible example of the force which is exercised by this principle
among the vegetables is shown in some parts of the world where the Aloe
flourishes in a wild state. In our colder clime the Aloe, though it does
live in the open air, is a slow-growing plant. But, in its own land, it
shoots up with a surprising vigour, and its sharply pointed and
saw-edged leaves are said to grow to the extent of six inches in a
single night.
Taking advantage of this rapid, and, at the same time, powerful growth,
the natives, when they want to punish a man with more than ordinary
severity, tie him hand and foot, and bind him to the earth just over a
sprouting aloe plant, and leave him there. In twenty-four hours the man
is nearly certain to be dead, the aloe-leaf having forced itself
completely through his body. Or, if he be not actually dead, he lives in
frightful tortures, which are continually increased by the flinty point
and notches forcing themselves slowly, but surely, through the body.
* * * * *
FOR an example of the Gimlet we may take the ovipositor of the Sirex, an
insect which I believe has no popular name. It is coloured much after
the same manner as the hornet, and is often mistaken for that insect by
those who are not versed in entomology. And, as its long and straight
ovipositor is generally taken for a hornet’s sting, the insect assumes a
double terror to the ignorant.
Now, the real fact is, that in its larval stage of existence the Sirex
feeds upon the wood of the fir-tree--a diet which, to our ideas, is
about as unsatisfactory as can well be imagined. In order that the young
Sirex may be within reach of food, the egg must be introduced deeply
into the body of the tree, and, for the egg to be so received, a channel
must be cut for it.
This is done by means of the marvellously formed ovipositor. Many
admirable descriptions have been given of the head of this instrument
and its boring powers, but I am not aware that any one has noticed the
secondary cutting blades that are set along the shaft of the principal
borer, and which answer exactly the same purpose as the spiral cutting
edge of the gimlet or auger.
Not being desirous of repeating my own observations in different words,
I transfer to these pages a short account of the ovipositor of the
Sirex, as examined by me when writing my work on British Insects,
entitled “Insects at Home,” and published by Messrs. Longmans and Co.:--
“I very strongly recommend any of my readers who may obtain a female
Sirex to disengage the actual borer from its two-bladed sheath, and
examine it with the aid of a microscope. A half-inch object-glass will
give quite a sufficient power.”
[Illustration: ŒSTRUS. BORING TOOL OF SIREX AND LARVA.]
[Illustration: AUGERS.]
[Illustration: BRADAWLS.]
“It is straight, stiff, and elastic, as if made of steel, and, if bent,
will spring back to its proper form with the elasticity of a Toledo
rapier.
“But the borer possesses an auxiliary cutting apparatus which places it
far above the rymer in point of efficacy. Even with an ordinary
magnifying lens, it is easy to see that the end of the borer is
developed into a sharp head, very much resembling that of a
boarding-pike, and that the outline of the shaft is broken into a series
of notches.
“The half-inch glass, however, discloses a marvellous example of
mechanical excellence. The head of the borer is then seen to be armed
with long, sharp teeth, slightly curved inwards, and acting just as does
the carpenter’s ordinary centrebit.
“So much for the head of the borer: we will now turn to the shaft.
“It appears that, in order to make a clean-cut hole for the reception of
the egg, the shaft of the borer has to finish the task which the head
begins. Accordingly, it is armed on each of its sides with a series of
hard, sharp-edged ridges, running diagonally across it, and acting
exactly as do the sharp ridges of a coffee-mill.”
In point of fact, the ovipositor of the Sirex is the natural type of the
improved gimlet of the present day. Instead, however, of having a
single, spiral, sharp-edged groove running along the whole length of the
shaft, it has a series of small, sharp blades, set exactly in the same
line as is taken by the spiral groove, and acting in exactly the same
manner--i.e. by cutting out successive portions of wood, and, by the
diagonal position of the blades, throwing out the debris as fast as it
is cut.
I cannot but think that, if any modern tool manufacturer could take as
his model the saw-like ovipositor of the Tenthredinidæ, and the
auger-like ovipositor of the present insect, he would produce a series
of most valuable implements, possessing powers far beyond those of
ordinary tools.
These short blades are arranged just like the “studs” on modern shells,
and very much resemble them in shape, though not in material.
* * * * *
THE Auger finds also a natural representative in the ovipositor of an
insect.
That of the common Gad-fly (_Œstrus bovis_) is most beautifully
constructed. It is tubular in form, and is of a telescopic nature,
consisting of four tubes of different sizes, the smaller fitting into
the larger just as is done with the joints of a common telescope, or
those of a Japanese fishing-rod.
The end of the ovipositor is developed into little projections, some of
which are armed with hard, sharp points, which act exactly like the
cutting edge of the auger. This elaborate appliance is necessary on
account of the thick, tough skin of the ox, which the Gad-fly has to
penetrate before it can deposit its eggs. Perhaps the reader may be
aware of the fact that the modern system of cutting channels in stone
with the diamond point, as was so well exemplified in the Mont Cenis
Tunnel, is but an imitation, and an imperfect one, of the method adopted
by the Gad-fly. We shall soon recur to this instrument.
STRIKING TOOLS.
If we search the records of antiquity as left by races of men that have
for countless ages vanished from the face of the earth, we shall find
that in some shape or other the Hammer was a tool in constant use, and
that in principle, though not in material, there was no difference
between the Hammer of the Stone Age and that of a blacksmith of the
present day.
The development of the instrument can easily be traced, especially as it
is a tool which does not admit of much elaboration.
The original hammer was evidently a simple stone, and answered equally
as a tool and a weapon. As, however, man progressed towards
civilisation, he found that the stone itself was insufficient for his
needs, and that he required much more force. The most obvious mode of
doing so was to take a larger stone, but this expedient soon became
valueless, inasmuch as a large stone was a cumbrous instrument to
handle, and could not be directed with any certainty or delicacy.
The principle of the lever was then applied to the stone, which was
affixed to a handle, and thus became elevated into the rank of a
comparatively civilised tool. Sometimes the stone had a hole bored
through it, into which the handle of the hammer was inserted, as is the
case with most of our present hammers and pickaxes. Sometimes the end of
the handle was enlarged, and the stone thrust through it, as is now done
with the axes of Southern Africa. Sometimes a long, flexible rod was
used by way of handle, the centre of it taking two turns round the
stone, and the ends being lashed together. Handles thus made may be seen
in any blacksmith’s forge of the present day.
The tool thus made was soon developed into various forms for different
uses. By lengthening and pointing the head, it became a pick for
loosening the earth. By widening and flattening the head, it became a
hatchet; and, by performing the same alteration in the pickaxe blade, it
became an adze. I possess a singularly ingenious tool from Borneo, in
which the head is movable, so as to be used as a hatchet or adze at
pleasure.
In Demmin’s “Weapons of War” many such hammers and axes are figured.
One of them is very remarkable. It is an ancient war-hammer made of
black stone, and is shaped exactly like a pickaxe, except that one end
of the head is carved into a semblance of some animal’s head. The handle
is passed through an oval hole in the centre, just like our pickaxes of
the present day. This remarkable example of the art of the Stone Age was
found in Russia. The head was nearly a foot in length.
* * * * *
NATURE possesses many examples of this principle, of which I have chosen
two, namely, the Woodpecker and the Nuthatch.
[Illustration: NUTHATCH.]
[Illustration: WOODPECKER.]
[Illustration: HAMMER.]
The wonderful power of beak possessed by both these birds is familiar to
every one, but it is not so generally known that they do not merely peck
after the usual fashion among birds, _i.e._ delivering the stroke with
the force derived from the neck alone. These birds have an additional
leverage. Grasping the tree firmly with their feet, they not only peck,
but swing their whole bodies with each stroke, bringing their weight to
bear upon the object. They thus convert themselves into living hammers,
the feet acting the part of the human hand, the body of the bird being
analogous to the handle of the hammer, and the head playing the same
part in both cases.
In England these birds are not known as well as they ought to be, partly
because they are both very shy creatures, and partly because the gradual
extinction of forests has deprived them, and especially the Woodpecker,
of their undisturbed homes. Yet those who are early risers may see both
birds in places where their presence is quite unsuspected, except,
perhaps, by those who can recognise the signs which they have left
behind them.
There is a common saying to the effect that “a carpenter is known by his
chips,” and the proverb is equally true of the Nuthatch and the
Woodpecker. Nutshells scientifically split asunder, and jammed into the
rough bark of a tree-trunk, betray at once the Nuthatch to the eye of a
naturalist; while an accumulation of shattered bark, splinters of wood,
and similar debris announces, in equally bold type, that a Woodpecker
has been at work.
The power of the Woodpecker’s beak may be gathered from Wilson’s
well-known account of an Ivory-billed Woodpecker, which he had wounded
and was trying to rear. While staying at an hotel, he locked the bird in
his room, and, on returning within an hour, found an astonishing state
of things.
“He had mounted along the side of the window, nearly as high as the
ceiling, a little below which he had begun to break through. The bed was
covered with large pieces of plaster, the lath was exposed for at least
fifteen inches square, and a hole large enough to admit the fist opened
to the weather boards, so that in less than another hour he would
certainly have succeeded in making his way through.
“I now tied a string round his leg, and, fastening it to the table,
again left him. I wished to preserve his life, and had gone off in
search of suitable food for him. As I re-ascended the stairs, I heard
him again at work, and on entering had the mortification to perceive
that he had almost ruined the mahogany table to which he was fastened,
and on which he had wreaked his whole vengeance.”
The beak of the Woodpecker was employed upon its new master quite as
forcibly as upon walls and furniture, but Wilson was of too generous a
nature to resent his injuries, and lamented sincerely when the bird
died.
The reader will probably observe that the Hammer which has been given as
an illustration of this principle is the ordinary geologist’s hammer,
and that it has been selected because its head is so formed that one end
can be employed for the usual tasks of a hammer, while the other end,
with its slight curve and sharp point, is, in fact, a sort of pickaxe,
and used for the same purposes. Indeed, this instrument is an almost
exact reproduction of the stone hammer which has already-been mentioned,
the blunt end being represented by the carved head, and the sharp end by
the pickaxe point.
GRASPING TOOLS.
Already we have spoken of the Shears and Scissors, together with their
mode of action and dependence upon leverage. We now come to a set of
tools which, although equally dependent on leverage, develop that power
by grasping instead of cutting. Without these tools, the arts and
sciences could have scarcely made themselves felt, as there are but few
manufactures in which the artificer does not require a grasping power
far superior to that of the human hand.
Perhaps the enormous power of the Pincers is never shown to better
advantage than in the great iron-works, where enormous masses of
white-hot metal have to be brought under the blows of the steam hammer.
I do not know of anything which affords a more imposing realisation of
the Divine command that man is to subdue the earth as well as to
replenish it. There is the vast hammer, striking blows which are felt
throughout a large area as if a succession of earthquakes had been let
loose. In the furnace there is an enormous mass of iron, heated to such
a degree that an unpractised eye could no more dare to look at it than
to stare a midsummer sun out of face.
Where are the armies who are to cope with such forces? A few stalwart
and grimy men come forward, each man with a curious but unmistakable air
of one who wages a war of giants. The furnace door is opened, and out
rushes a blinding light which strikes on the eyeballs like a shock of
electricity. The men seize the handles of an enormous pair of Pincers,
suspended in the middle by a chain, and though no unpractised eye can
distinguish the glowing iron from the enveloping fire, they run the
Pincers into the furnace, seize the iron, swing it to the anvil, and
turn it this way and that way as easily as if it were a feather, while
the blows of the gigantic hammer descend upon it, enveloping them in a
torrent of sparks which spurt as if they were mere splashes of water,
and seem to do them no more harm.
Taking the minor exposition of the Pincers principle and their use, we
may mention the ordinary Pincers which are mostly used for drawing
nails. Then there are the smaller Pincers called Pliers, all of which
are constructed on the same principle, and the chief of which are the
Round-nosed Pliers, the Long-nosed Pliers, and the Gas Pliers. Sometimes
a mixture of the Hammer and the Pincers is ingeniously contrived, as in
the tool which is represented on the right hand of the illustration.
[Illustration: MUSSEL-SHELL. EARWIG. LOBSTER-CLAW.]
[Illustration: SUGAR-TONGS.]
[Illustration: PINCERS.]
Then we have the still smaller and feebler Pincers of civilised life,
such as the Sugar-tongs and the ordinary Coal-tongs of our firesides.
Anatomists could have had no practical existence without the Pincers, of
which their beautifully constructed and much-elaborated forceps are but
variations.
Take, again, the dentist, with his series of shining instruments, which
he so carefully keeps out of sight until he has got his patient safely
in that awful chair, and which glide, as by a conjurer’s trick, empty
into an open mouth, and return in a few seconds with a tooth between
their polished jaws.
* * * * *
ALL these instruments have their parallels in Nature, and in many
instances the natural pincers might supply useful hints to modern
tool-makers.
In the left-hand upper corner of the illustration is shown the common
fresh-water Mussel, which is so plentiful in almost all our rivers and
many of our ponds. Its scientific name is _Unio margaritiferus_. The
latter title, which signifies “pearl-bearing,” is given to it because
it furnishes the British pearls which were at one time so highly valued.
Like other bivalve molluscs, this Unio has the two halves of the shell
fitting quite tightly upon each other, and, when they are drawn together
by the contraction of the internal muscles, they can give a very severe
pinch. In many uncivilised parts of the world the natives take advantage
of this property, and use them as tweezers, chiefly for the purpose of
pulling out hairs which they are pleased to think are not needed.
I need not state that with all bivalves the power is increased in
proportion to the size of the shell. Even an Oyster can pinch most
severely, while the Giant Clam, the shell of which weighs some four
hundred pounds, could nearly take off a man’s leg if it seized him.
Mr. J. Keast Lord, in his “Naturalist in British Columbia,” relates an
amusing story that was told to him by an old settler respecting the
power of the Clam’s grip:--
“You see, sir, as I was a-cruising down these flats about sun-up, the
tide jist at the nip, as it is now, I see a whole pile of
shoveller-ducks snabbling in the mud, and busy as dogfish in herring
time. So I creeps down, and slap I let ’em have it. Six on ’em turned
over, and off went the pack, gallows scared, and quacking like mad.”
“Down I runs to pick up the dead uns, when I see an old mallard
a-playing up all kinds o’ antics, jumping, backing, flapping, but fast
by the head, as if he had his nose in a steel trap; and when I comes up
to him, blest if a large Clam hadn’t hold of him, hard and fast, by the
beak.”
“The old mallard might ha’ tried his hardest, but may I never bait a
martin-trap again if that Clam wouldn’t ha’ held him agin any odds till
a tide run in, and then he’d ha’ been a gone shoveller sure as shooting.
So I cracked up the Clam with the butt of my old gun, and bagged the
mallard.”
Of course the reader will remember that this was only an ordinary Clam,
and not one of the giant race.
* * * * *
BELOW the shell are two very perfect instances of natural Pincers, each
acting in a different manner, but on the same principle.
The Earwig is too familiar to need much description, but I may as well
state that its pincers are not primarily intended as weapons, although
they can be so used on occasion. (I was about to say, at a pinch, but
refrain.) They resemble our ordinary pincers in that both blades move
equally, and they are so completely under the control of their owner,
that the insect uses them with a delicacy of touch that a lady’s fingers
could hardly surpass. They are really tools, and not weapons, and are
employed for the purpose of folding the wide and delicate wings under
the tiny elytra.
There is another insect called the Scorpion-fly (_Panorpa_), the male of
which is furnished with a pair of pincers at the end of a long and
flexible tail, articulated just like the tail of a scorpion, and moved
in exactly the same manner. It is but a little insect, but its gestures
are so menacing as it flourishes its tail about, that non-entomologists
may well be pardoned for being afraid of it. Moreover, small as are the
pincers, they really can give a smart nip, and make themselves felt on
the human skin.
* * * * *
IF we want examples of exceedingly powerful pincers, we need only go to
the Lobsters and Crabs, especially to the latter, whose claws are often
of enormous thickness in proportion to the size of the animal. All those
who have visited the seaside know how severe is the pinch of the common
Green Crab, comparatively small though it be, and the same may be said
of the river crayfish, which is, in fact, a lobster in miniature.
As to the lobster itself, fishermen are so well acquainted with the
power of its claws, that they tie them together with string as soon as
the animal is caught. Formerly they used to “peg” them, _i.e._ drive a
wooden peg into the joint so as to prevent it from moving. This custom,
however, is now prohibited by law on account of its cruelty.
The power of the Crab’s claws is so great that a bite from a large Crab
will inflict a severe injury, and render a hand helpless. It has more
than once happened that men who have been feeling for Crabs in the
recesses of the rocks at low water have been seized, and seriously
imperilled, not being able to release themselves from the gripe.
Indeed, it is said that there have been instances where the Crab has
held so tightly, that the man has been drowned by the returning tide, no
one having come to his assistance. I am, however, inclined to doubt this
statement, thinking that the Crab would not be likely to remain in its
hiding-place very long after the water came up. Still, that such an idea
should be currently believed in many parts of England shows the
estimation in which the gripe of the Crab’s claw is held.
TOOLS
CHAPTER IV.
POLISHING TOOLS.--MEASURING TOOLS.
Files and Sand-papers.--The Sheffield File and its Structure.--The
Equisetum, Mare’s Tail, or Dutch Rush.--Beauty of its Surface when
seen through the Microscope.--Sand-paper.--Skin of Dog-fish, Skate,
and Shark.--Skate-skin used for Sword-handles.--Distinction between
the File and Sand-paper.--Measuring Tools.--The Plumb-rule and the
Level.--Their Use in Tunnelling.--The Measure and its Uses.--The
Two-foot Rule and the Tape Measure.--Ovipositor of
Gall-fly.--Tongues of the Woodpecker, Wryneck, and Creeper.--The
Spirit-level and its Uses.--Theodolite and Callipers in Nature and
Art.--The Contouring-glass.--Pincers of Earwig again.--Jaws of
Insects.--The great Sialis of Columbia.
FILES AND SAND-PAPERS.
Having now examined the analogies between the cutting, boring, striking
and grasping tools of Nature and Art, we come to those finishing tools
which smooth and polish the surface.
The first is the File, an instrument which needs but little description.
It consists of a surface of hardened steel, broken up into rough-edged
teeth of infinite variety, according to the work which the file has to
do. It is rather remarkable, by the way, that at present the English
files are infinitely superior to those produced in any other part of the
world; that their teeth are all made by hand; and that a genuine
Sheffield file will first cut its way through a piece of iron in half
the time that would be occupied by a file of any other nation, and then
would easily cut its antagonist in two.
* * * * *
AS long as the File is intended to work upon metal, there is little
difficulty in its manufacture, except that no machinery has yet been
invented which can give the peculiar edging of the ridges, and to which
is owing the unmistakable “bite” of a real English file.
But there are occasions when the hand of the most cunning file-maker is
baffled, and when it is necessary to cut files so delicate that the
unaided human eye cannot trace their teeth. Art, therefore, has recourse
to Nature, and the cabinet-maker, who cannot obtain any file made by
human hands which will answer his purpose in the higher branches of his
trade, makes great use of the “Dutch Rush,” as he calls it. It is not a
rush at all, but simply a species of Mare’s Tail, or Equisetum, a plant
which fills in profusion almost every marshy spot in England.
[Illustration: EQUISETUM.]
[Illustration: FILE.]
The peculiar fitness of the Equisetum for this purpose cannot be
appreciated even by those who use it until it has been viewed under the
microscope. I have now before me a small piece of Equisetum, placed
under a half-inch power, and viewed by direct illumination, it being
treated as an opaque object.
The microscope reveals at a glance the source of the power which the
ingenuity of man has taken advantage of. The surface of the Equisetum is
seen to be composed of myriads of tiny parallel ridges, each ridge
bristling with rows of flinty spicules, looking very much like the
broken glass upon the top of a wall. Minute as they are, these spicules
can do their work, and they enable the joiner to finish off work in a
manner that could not be accomplished by any tool made by human hands.
I find, by recent inquiries, that modern joiners scarcely, if ever, use
the Equisetum, preferring emery-paper as cheaper and more expeditious,
and knowing that the popular eye is not able to appreciate the
difference of the surface obtained by the Equisetum from that which is
given by the finest emery-paper ever made. Wood-carvers, however, if
they be of the conscientious kind, and love their work for its own sake,
adhere to the Dutch Rush, and are all the happier for it.
* * * * *
PASS we now to the coarser kinds of polishers, the chief of which is
popularly known as Sand-paper, and is made by coating some tissue with
glue, and scattering upon it sand of different qualities, according to
the work to be done. Sometimes, when the work is rough, the sand is
large, rough, and coarse, and sometimes, when the work is fine, the sand
is so carefully sifted before it is scattered on the glued paper, that
there is little distinction between the sand-paper and emery-paper.
Linen, by the way, is generally used instead of paper, as being more
enduring, less liable to crack, and capable of being folded so as to
obtain access to crevices which paper could not touch.
[Illustration: DOG-FISH SKIN, MAGNIFIED.]
[Illustration: SAND-PAPER, MAGNIFIED.]
* * * * *
AGAIN in Nature we find a parallel, and the coarse Sand-paper of modern
Art has long been anticipated in the scale-clad skins of many fishes.
The accompanying illustration is taken from the skin of a Picked
Dog-fish found by myself lying dead on the rocks in Bideford Bay. I cut
off a piece for transmission to the draftsman, and found that not only
did it feel exactly like cutting through a piece of very common
sand-paper, but that it blunted the edge of a new knife in exactly the
same manner as would have been done by the roughest of sand-paper.
This kind of skin is common to all the shark tribe (including the
Dog-fishes, which are but sharks in miniature), and to the Skate,
Saw-fish, &c. I have now before me a small, but perfect example of the
Saw-fish, the surface of which is covered with flinty scales like those
of the Dog-fish, but very much smaller, requiring the aid of a
magnifying lens to distinguish them. Even to guess at the number of them
is impossible, for they cover the whole of the body, and extend to the
very end of the beak, in some places glittering in a strong light as if
pounded glass had been sprinkled all over the fish. One of the most
interesting points in their structure is the manner in which they reach
the rounded jaws, and there become converted into teeth powerful enough
to crush the animals on which the fish live. The structure of these jaws
will be explained in a future chapter.
Some of the skates and sharks have these scales of great size, so as to
show their formation almost without the aid of a magnifying-glass. This
is the case with a species of skate, the skin of which is used by the
Japanese for wrapping round the handles of their best swords, and which
is greatly valued by that nation, the sword being an almost sacred
article in the eyes of a Japanese.
There is a well-known museum in which these swords are labelled as
having handles of “granulated ivory.” Now, in the first place, there is
no such thing as granulated ivory; and, in the next, a mere glance ought
to tell the observer that the so-called ivory is a skin of some sort,
worked upon the handle while wet, and kept in its place by copper studs.
Even the junction of the edges is perceptible, and yet the authorities
of the museum in question, although they have been repeatedly corrected,
still persist in calling the skate-skin by the absurd title of
granulated ivory.
However, if ivory could be granulated, it would certainly look very much
like the skate-skin. When examined closely, the scales, whether of
Dog-fish, Skate, Shark, or Saw-fish, are seen to resemble hexagonal
cones, not coming quite to a point, but truncated, so as to have an
hexagonal flattened tip. They are almost of a flinty hardness,
especially at their tips, and on inspection of them the observer is not
surprised at the use of Dog-fish skin in place of sand-paper.
Perhaps the reader may ask why the Equisetum should be taken as the
prototype of the file, and the skin of the Dog-fish as that of
sand-paper. The reason is this. The flinty points of the Equisetum are
set upon parallel ridges something like those of a file, while the
scales of the Dog-fish are without any apparent order, being crowded
against each other like the cutting particles upon the sand-paper. That
there should not be an order, and that a definite one, is out of the
question. But it has not yet been detected by human eyes, and therefore
may be practically treated as non-existent.
TOOLS OF MEASUREMENT.
In many of the arts, more especially those which belong to engineering
and carpentering as a part of architecture, it is absolutely necessary
to make sure of a perpendicular line, _i.e._ a line which, if continued,
would reach from any point of the earth’s surface to its exact centre
below and its zenith above. Were it not for the power of producing this
line, none of the great engineering works of modern or ancient days
could have been undertaken.
Take, for example, the wonderful tunnels which have been driven through
the earth, of which the Mont Cenis Tunnel is one of the greatest
triumphs of modern engineering. Beginning, as the workmen did, at
opposite ends of a tunnel many miles in length, and labouring only by
the lines laid down by the engineers, the men worked steadily on until
they met in the centre.
A few blows, and the then narrow dividing wall was shattered, the men
shook hands through the aperture, and then, after enlarging it, leaped
wildly from one side to the other, having successfully solved the great
problem. With such marvellous precision had the lines been laid, that
only a few inches had to be smoothed down on either side, and the sides
or walls of the tunnel showed no traces of the junction.
So rapid has been the progress of engineering that a tunnel of a mile in
length would, within the memory of man, have been thought as daring a
project as was the Mont Cenis Tunnel, which has just been given as an
example. Indeed, I know of a railway tunnel, not quite a mile in length,
where the engineers had committed some error, so that the two halves,
instead of meeting exactly, overlapped each other so much that the
mistake was only discovered by the workmen, who heard the strokes of
their companions’ picks on their sides, and not in front. Consequently,
a great waste of time took place, and the centre of the tunnel had to be
made with a double curve, like the letter S, and trains are obliged to
slacken speed until they have passed it.
Those who have lived long enough to remember the current literature of
the past generation will call to mind the ridicule that was cast upon
the idea of a tunnel that should pass under the Thames. That it would be
useful if it could be completed, no one ventured to doubt, but that such
an idea could be conceived by any one out of a lunatic asylum was rather
too much for the journalists of the day. However, the tunnel was made,
and so proved the theorists wrong on the one side. And, when made, it
was of very little use, which proved them wrong on the other side. Now
the proposal to carry a submarine tunnel from England to France excites
not half the opposition that was elicited by the comparative
child’s-play of a tunnel under the Thames.
The only mode of laying down the lines on which the men worked is by
suspending very heavy balls to very fine wires, and then, by means of
delicate optical instruments, ascertaining whether the wires are in line
with each other.
Familiar instances of the use of this principle may be seen in the
plumb-rule and level of the builder or carpenter. The latter, with a
base of ten feet in length, is often used by the gardener when he wishes
to lay the absolutely level lawns that are required for our modern game
of croquet, where the hoops are scarcely wider than the balls, and the
lawn has in consequence to be nearly as level as a billiard table.
I may here remark that the name plumb-rule is derived from the Latin
word _plumbum_, or lead, in allusion to the leaden weight at the end of
the string. The word “plumber” is due to the same source, and signifies
a worker in lead.
* * * * *
THESE invaluable aids to the development of civilisation are due to one
principle, namely, that which we call Gravitation, but which ought more
properly to be termed Attraction, and which attracts all parts of the
earth towards its centre. We are all familiar with the anecdote of
Newton and the falling apple, which may be true or not, but which at
all events bears on the present subject. No matter on what portion of
the spherical earth a tree may be, every fruit becoming disengaged from
it is attracted to the earth, the line which it takes, unless disturbed
by external forces (such as wind, &c.), being that which passes from the
zenith to the centre of the earth.
[Illustration: FALLING FRUIT.]
[Illustration: PLUMB-RULE.]
[Illustration: LEVEL.]
This imaginary line is a perfect perpendicular, and the visible line
which is formed by the delicate wire of the tunnel-boring engineering
instrument, or the comparatively coarse string of the plumb-rule and
level, are approximations sufficiently close for practical purposes. So
it is in a mathematical proposition. As mathematical lines have no
breadth, they are simply indicated or represented by the lines of the
figure, the bodily eye being incapable of seeing what is perfectly
visible to the mental eye, namely, length without width. So the wire and
string perform in practical work exactly the same office which is
fulfilled by the lines of a mathematical proposition drawn on paper.
We have already, when treating of the Fall-trap, seen how this principle
is brought into operation by those who are utterly incapable of
discerning the physical principle, though they can apply it materially
with wonderful effect.
* * * * *
IT is, perhaps, needless to mention the value of the Measure to any
handicraftsman.
I well remember that when, some twenty-four years ago, I was taking
lessons from a carpenter in the art of making ladders, gates, fences,
hurdles, and other rough-and-ready work, my quaint old tutor related an
anecdote of and against himself. He very ingeniously set me to work at
boring the auger-holes in the gate-posts which were to be united by the
mortise chisel and mallet, and to sweeten the rather severe, because
unaccustomed, labour, told me that, when he was a boy, he was doing just
the same thing.
Being rather tired of twisting the auger handle (and no wonder either),
he withdrew the instrument, and put his finger into the hole by way of
ascertaining its depth. Immediately he found himself on his back, having
received a tremendous box on the ear from his father, whose parental
wrath was excited by the idea of his son condescending to use his finger
by way of measure, when he had a two-foot rule in its own special
pocket.
There are, however, many cases where even a two-foot rule would be
insufficient for the work, and where a measure of thirty or forty feet
is needed.
Now, there is no doubt that by means of a two-foot, or even a six-inch,
rule any number of feet might be measured accurately; but, considering
the number of junctions that have to be made, it is not likely that any
pretence to accuracy could be insured.
Then, a rod of forty, or even of twenty, feet in length would be awkward
and unmanageable, and the only plan left is to take a string or cord of
the requisite length.
Even here, however, is a difficulty. The string would not allow of short
measurements, such as inches, being written upon it. Let, however, a
broad tape of inelastic material be substituted for the string, and all
is easy enough.
The next plan is to provide for the portability of the tape in question,
to insure its reduction into the smallest possible compass, and to be
sure that it is not twisted so as to damage its accuracy. These objects
are all attained by the ordinary Tape Measure of the present day, which,
whether it be a yard measure in a lady’s workbox, or a surveyor’s
measuring tape, is a ribbon of comparatively inelastic material, coiled
up when not wanted, and capable of being drawn out to its fullest
extreme when needed.
Putting aside the breadth of the line, and consequently disregarding the
liability to twist, we have in the Fishing-reel of the modern angler an
exact case in point. So we have in the lady’s yard measure, and in the
gardener’s or builder’s tape, all these being modifications of the same
idea.
[Illustration: OVIPOSITOR OF GALL-FLY.]
[Illustration: SPRING MEASURE.]
Suppose now that we pass to Nature, so as to ascertain whether any such
provisions were in existence before it was imitated, however
unconsciously, by man. This certainly was the case with one of the
commonest and most insignificant of our insects, the little Gall-fly,
belonging to the genus Cynips. It could not lay its eggs without the aid
of a very long ovipositor, and, owing to structural details, it cannot
carry that ovipositor in a straight line, as is done by many insects,
some of which have already been mentioned. Accordingly, it is coiled up
exactly like our measuring tapes, and can be unrolled when needed. The
long, protrusible tongues of the Wryneck, Creeper, and Woodpecker are
examples of a similar structure, the tendinous portions being coiled
round the head when not needed.
THE SPIRIT-LEVEL.
Having now seen how the forces of Nature enable us to produce a
perfectly perpendicular line, we will see how the same force, though
applied in a different manner, enables us to produce a perfectly
horizontal line, the intersection of the two lines producing a right
angle.
[Illustration: FLOATING BUBBLE.]
[Illustration: SPIRIT-LEVEL.]
The measuring tool in question is called the Spirit-level, and is
represented on the right hand of the accompanying illustration. Its
construction is very simple, consisting of a tube, nearly filled with
spirit, and having just one bubble of air in it. Now, owing to the force
of gravitation, the air-bubble must always be uppermost. Consequently,
if the tube be a perfect cylinder, whenever it is held so that the
bubble is in the centre, the tube must be horizontal, a hair’s breadth
of deviation altering the line. I may here mention that, as far as the
principle of the instrument goes, water would serve the purpose as
effectively as spirit. But as in cold weather the water might freeze,
and so burst the tube, as well as being useless until it was thawed,
spirit is always substituted.
This instrument is used for various purposes. Sometimes it is employed
for levelling billiard tables, or for ascertaining the exact level of
walls and other parts of buildings. Surveyors could scarcely do their
work without the Spirit-level, which forms an important part of their
chief instrument, the theodolite. Indeed, the new science of land
drainage, by which the tough, unproductive clay soil is converted into
fertile earth, is entirely dependent on the use of the Spirit-level,
which detects the slightest rise or fall in the ground.
A most ingenious modification of the Spirit-level is used by military
engineers, and is known by the name of the “Contouring-glass,” a term
which requires some explanation.
It is of the utmost importance that a military engineer should be able,
whether on foot or on horseback, to ascertain the approximate heights of
the various points which he visits, the efficiency or failure of a
battery very much depending on the comparative elevation of the spot on
which the battery is placed, and that of the place against which its
fire is directed. In an unknown country, of which no detailed maps
exist, an invading force must of necessity depend on the extemporised
surveys of their engineer officers, and one of the most valuable of
their devices is the system of Contouring, invented, as far as I know,
by the late Colonel Hutchinson, R.E.
The idea is simple enough. A hill is seen, and the engineer makes a
sketch of it before he ascends. At the foot he halts, and marks the spot
where his foot presses the earth. He then looks in front at a spot
exactly on the level of his eye, marks it, and walks to it. He then
draws a line across his sketch, at the exact spot on which he is
standing, and that is the first “contouring line.” Others follow, until
he has reached the top of the hill.
Now, if he can trust himself to look exactly horizontally, he has
ascertained the elevation of every part of the hill. He knows the height
of his eye from the sole of his foot, and calculates accordingly.
Suppose, for example, that it be five feet, and that ten contouring
lines are marked, he knows that the entire height is fifty feet, and
that each line means an elevation of five feet.
This is a very excellent theory, but one which is not reduced to
practice so easily as it looks. There is nothing more deceptive than a
contour, especially upon an irregular hill, the invariable mistakes
being either greatly to overrate or underrate the height of the contour.
When I took my first lesson in this art I caused much amusement to the
professor under whom I was studying, by making Shooter’s Hill consist of
about seventeen contours. However, as many military students made very
much the same mistake, I was not so humiliated as I supposed.
Of course, if a surveying officer be mounted, he takes the contour line
as measured from his eye to the ground through the centre of the saddle.
After some practice the eye becomes so much accustomed to the contouring
lines that they are taken almost mechanically; but, until this result be
gained, an absolute proof is needed, which is furnished by the
Contouring-glass--which, by the way, is not a glass at all, after the
common acceptation of the word.
It is a simple brass tube about three inches long, not thicker than a
man’s little finger, and open throughout. A small spirit-level is fixed
on its lower surface, and on the very centre of the upper surface is a
tiny steel mirror, which projects downwards like a knife-blade. In order
to get a “contour,” the observer looks through the tube, slightly
depressing its end. He then gradually raises it, still looking through
it. As the tube becomes exactly horizontal the bubble in the
spirit-level is reflected in the little mirror, and the object on which
the tube is directed is in consequence on a level with the observer’s
eye.
At first the management of the contouring-glass is rather tedious; but
after a little practice it can be used without pausing for a single
step.
* * * * *
INVALUABLE as is the Spirit-level, with its various modifications, it is
nothing but an adaptation of that natural law which causes the bubbles
to float on the surface of a stream instead of being submerged below
it. We have all seen the multitudinous bubbles of soda-water, or of any
effervescing liquid, and have noticed how they are very small when
generated, but enlarge quickly, and rise to the surface with a rapidity
equal to their enlargement. The same phenomena may be observed in any
water-fall, or even in the very familiar and unpoetical operation of
pouring beer from a jug into a glass.
The reader will see that in the plumb-rule, the level, and the
spirit-level one single principle is employed, namely, the attraction of
matter towards the centre of the earth. In the two former instruments
this attraction gives a vertical line, and in the latter it gives a
horizontal line, but the principle is the same in both.
CALLIPERS.
[Illustration: JAWS OF SIALIS.]
[Illustration: CALLIPERS.]
We conclude the history of measuring tools with the Callipers. For
ordinary purposes, and upon a plane surface, the Compasses answer every
purpose. But there are various arts, especially sculpture, in which the
compasses, with their straight legs, are absolutely valueless, and their
place must be supplied by a differently shaped instrument. For example,
no ordinary compasses could measure the exact distance from the nostril
to the back of the head, or even touch two points at opposite sides of a
limb, and it is therefore necessary to have compasses with curved legs.
These are termed Callipers, and can be used on a plane as well as on a
rounded surface.
* * * * *
NATURAL Callipers are plentiful enough, and may be found extensively
among the insect tribes. There are, for example, the pincers of the
Earwig, which have already been described on page 259, and which are, in
the common species, formed exactly like the Callipers of the sculptor.
Then we have various insect jaws, especially those of the carnivorous
species, one of the most curious being the large insect which is shown
in the illustration, upon a very reduced scale. In the male the jaws are
exceedingly long and curved, as may be seen by reference to the
illustration. I have now before me a pair of sculptor’s callipers, and
the resemblance between them and the jaws of the Sialis is strangely
close, the curve being almost exactly the same in both cases.
The scientific name of this insect is _Sialis armata_, and it is a
native of Columbia.
OPTICS.
CHAPTER I.
THE MISSIONS OF HISTORY.--THE CAMERA OBSCURA.--LONG AND SHORT
SIGHT.--STEREOSCOPE AND PSEUDOSCOPE.--MULTIPLYING-GLASSES.
The Camera Obscura.--Telescopes, Microscopes, and Spectroscopes,
and their separate Objects.--Structure of the Camera Obscura.--The
Double Convex Lens.--Its Use as a Burning-glass.--The Meridian Gun
in Paris.--Signification of the Word “Focus.”--The Human Eye and
its Analogies to the Camera Obscura.--Forms of various
Lenses.--Long and Short Sight.--Their Causes and Means of
Remedy.--Alteration of Sight in the Diver.--Long and Short sighted
Spectacles.--The Eye of Birds.--Its beautiful
Structure.--Washing-glasses and the “Nictitating”
Membrane.--Combination of Images.--Natural Stereoscopes.--The
Pseudoscope and its Effects on an Object.--The
Multiplying-glass.--The Eight Eyes of the Spider and their
Arrangement.--The Seventy Thousand Eyes of the Butterfly.--Form of
the Facets.
History seems to fall into natural divisions, and to write the records
of time in successive epochs, recording the advance of the human race.
Some of them have apparently disappeared except by the strange relics
which they have left behind, but though nothing is known of the men who
worked in these ancient times, they stamped their mark upon the earth,
and evidently left the world better than they found it.
A very admirable treatise on this subject has been written by the late
Rev. J. Smith, called the “Divine Drama of Creation.” In this work he
divides the progress of the human race into five acts, like those of a
drama. The first act is the Hebrew Mission, the second the Greek
Mission, the third the Roman Mission and the Middle Ages, the fourth the
National Mission, and the fifth the Universal Mission.
Certainly a scene of the last act is now in progress, and may be
entitled the Scientific Mission. The last hundred years have been indeed
the age of discovery, and, during that time, the life of civilised man
has been quite altered, so that practically his sojourn upon earth has
been doubled. Steam, with all its various applications, electricity, and
other kindred arts have become so intermingled with our lives, that it
is difficult to imagine what our state would be if we were suddenly and
utterly deprived of them. The loss to all would be incalculable, and not
the least of the losses would be that of ready communion with our
fellow-creatures.
Of these arts we will now take that which is named at the head of this
division of the book, and see how far it is a development of natural
facts.
THE CAMERA OBSCURA AND THE EYE.
I have already spoken of arts as being akin to each other. They are more
than this, and every day of the world’s progress teaches us that Art,
Science, and Manufacture are sisters, all born of one family, and all
depending mutually on each other.
Take, for example, our present theme--namely, Optics--and see how
dependent it is upon Manufacture and Art. Without the former, man could
not construct those beautiful telescopes, microscopes, spectroscopes, of
the present day, which are evidently but the precursors of instruments
which will work still greater marvels.
The first enables us to see solar systems without number, to which our
own, vast as it seems to us, is but as a grain of sand in the desert.
The next instrument makes revelations as marvellous of the infinitely
minute as does the telescope of the infinitely great, enabling us to see
living organizations so small that thirty-two millions could swim in a
cubic inch of water. The third, a comparatively modern instrument,
reveals the composition of objects, and can detect and register the
materials of which the sun and fixed stars are made, or detect an
adulteration in wine. It can adapt itself equally to the telescope and
microscope, and the very same instrument which will reveal the character
of an invisible gas in the Pole-star, when attached to the telescope,
can, when connected with the microscope, point out the presence of half
a corpuscle of blood where no other instrument could discover any trace
of it.
All these instruments, together with many others, will be described in
the present division of the work, and their analogies with Nature shown.
* * * * *
WE will now take the subject of the Camera Obscura, an instrument with
which the photographic apparatus of the present day has made most of us
familiar. As its action depends chiefly upon the glass, or lens, through
which the rays of light pass into the instrument, we will first explain
that.
A “lens” is a glass formed in such a manner that the rays of light which
pass through it either converge to a focus, or are dispersed, by means
of the law of refraction. Every one who has been photographed--and who
has not?--will remember that when the sitter has taken his position, the
photographer brings to bear upon him a circular glass fixed into a short
tube, and then looks through the instrument as if he were taking aim
with some species of firearm. It is no matter of wonder that when
savages see the photographic camera for the first time they are horribly
frightened, for there is really something weird-like in the appearance
of the lens thus presented.
Now, this lens is of the shape called “double convex,” both sides being
equally rounded, so that a section of it would be shaped very much like
a parenthesis (). The effect of this form of lens is to bring the rays
of light to a point at a given distance from the centre. This point is
called the “focus,” and is well known by means of the common
burning-glass, which will set fire to objects placed in its focus, while
itself remains quite cool.
I have seen lead pour down like water when placed in the focus of a
large burning-glass, and even the harder metals will yield to the power
of the sun’s rays when thus concentrated.
There is nothing which gives a more vivid idea of the amount of heat
thrown on the earth by the rays of the sun than the effects of a
moderately large burning-glass--say one of six inches in diameter. If we
trace a circle of this size on the surface of the earth, it does not
seem as if any very great amount of heat can be received, but when we
catch the rays of that circle in our glass, and bring them together upon
the focus, the amount of heat can be appreciated. The well-known
meridian gun in the Palais Royal is fired by the sun. A burning-glass of
no very great size is placed over the touch-hole of the gun, with which
its focus coincides. The lens is turned in such a manner that, as the
sun attains the meridian, its rays are thrown upon the touch-hole, and
consequently fire the gun.
The word _focus_ is the Latin term for a domestic hearth, and is used in
allusion to the heat which is manifested at the point on which the rays
of the sun converge.
It is evident that, after reaching the focus, the rays, if they be not
intercepted by some object, will cross each other, and form a large
image, but reversed. This part of the subject will presently be
explained.
* * * * *
THE accompanying illustration shows two figures, one representing the
section of a double convex lens made by the hands of man, and the other
that of a double convex lens as seen in Nature.
[Illustration: CRYSTALLINE LENS OF HUMAN EYE.]
[Illustration: DOUBLE CONVEX LENS.]
The former has already been explained. The latter is the double convex
lens of the human eye, by means of which the images of external objects
are conveyed to the brain. Whenever this lens becomes thickened by
disease, the sight is gradually dimmed, and at last total blindness is
the result. This disease is popularly called “cataract,” and until late
days was incurable. Now, however, any good oculist will attack a
cataract, and either partially or entirely restore the sight. This
operation is performed by carefully removing the convex lens, and
supplying its place with a glass lens, which throws the rays of light on
the same focus.
The figure shows the double convex lens of the human eye in its place.
* * * * *
HAVING now seen something of the properties of the double convex lens,
we will examine its application to the Camera Obscura.
The lens is placed on one side of the camera, and is so made that it can
be slid backwards and forwards, and the focus altered at will. The
camera itself is a box completely closed, so that no light can enter it
except that which passes through the lens. The latter is so arranged
that the rays which pass through it are crossed, and throw their image
on the opposite side of the camera. In the photographic camera a piece
of ground glass is placed at the end, so that the rays fall upon it, and
the operator can see whether the image is a good one. Of course the
figures are reversed, so that the sitter seems to be on his head, but
that is a matter of no consequence. Exactly the same effect is produced
by the marine telescope.
[Illustration: EYE AND IMAGE.]
[Illustration: CAMERA OBSCURA AND IMAGE.]
The general structure of the camera is shown in the illustration, all
needless details being omitted.
I may here remark that the term “camera obscura,” or dark chamber,
alludes to the fact that the box is completely closed, and, but for the
rays which pass through the lens, would be absolutely dark.
* * * * *
THE opposite illustration shows the most perfect camera obscura that can
be imagined, namely, the human eye. Here we have a dark chamber, a
double convex lens, and an image falling upon the back. Here the optic
nerve comes into play, takes cognisance of the image, and conveys the
idea to the brain. With a little trouble, a real eye, say that of an
ox, can be dissected out, and employed as a camera obscura, the operator
seeing in the back of the eye, or “retina,” the same image which the ox
would have seen if it had been alive.
In photography, the operator, when he has found that a perfect image is
thrown upon the ground glass, which represents the retina of the eye,
substitutes for it a sensitive surface, on which the rays are projected,
and which, by chemical means, produce a permanent instead of a fleeting
object.
* * * * *
EXAMPLES of other lenses may be found in Nature. She, moreover, can
perform a task which man has never even attempted, namely, the change of
form in a lens according to the duty which it has to do. How this
wonderful object is attained we shall presently see.
There is a form of lens extremely useful in Optics, namely, the
“Plano-convex” lens. This is, in fact, one half of a double convex lens,
the section being made through its edges, and the plane sides polished
as well as the convex. As, however, this is only a half of the double
convex lens, it does not need further explanation. Its natural
counterpart may be seen in the annexed illustration.
[Illustration: HUMAN EYE: SECTION OF CORNEA, &C.]
[Illustration: PLANO-CONVEX LENS.]
A somewhat more complicated form of lens is called the “Meniscus,” one
side of which is convex and the other concave. A good example of the
meniscus may be found in the old-fashioned watch-glass, before
watchmakers took to flattening them, and watch-wearers were not ashamed
to carry a “turnip,” in which there was room to spare for the works. If
a section of such a glass were taken, it would assume the form of a
half-moon. This, in fact, is the meaning of the term “meniscus,” which
is a Greek word, signifying a little moon. If the same glass were solid,
or even filled with water, it would form a “plano-convex” lens.
Of course the outer curve of the meniscus must be larger than the inner
curve, but in some cases the disproportion is very strongly marked, the
outer curve being very large, and the inner curve very small. An example
of such a meniscus may be seen in the human eye. If the reader will
refer to the illustration on page 280, in which the structure of the eye
is shown, he will see the meniscus lens in combination with the double
convex. The former has already been explained, and the latter is formed
by the vitreous humour which fills nearly the entire globe of the eye.
Its larger curve is due to the form of the eyeball, and the smaller to
the convex lens.
LONG AND SHORT SIGHT.
It has already been mentioned that the focus of a convex lens is shorter
in proportion to its convexity, and that in consequence its magnifying
power is increased. For example, the large glasses through which
pictures are viewed are comparatively thin in proportion to their
diameter, while the lenses employed for the highest powers of the
microscope are scarcely larger than small shot, and nearly as globular.
It naturally follows that any instrument to which a lens is adapted,
whether it be microscope or telescope, must depend for its focus on the
greater or less convexity of the lens in question.
[Illustration: FRAME OF OWL’S EYE. LENS OF DITTO.]
[Illustration: SHORT AND LONG SIGHTED EYES (WITH SPECTACLES).]
Again taking as our example the human eye, we find that there are very
few persons who from youth to age possess or preserve eyes which can
read small type at a moderate distance, and can clearly define the
outlines of distant objects. Nearly all people, even if in their youth
they possess good sight, lose it as they grow older. They can discern
distant objects well enough, but, when they come to reading, they are
obliged to hold the book at arm’s length before they can distinguish the
letters.
This defect is caused by the insufficient convexity of the lens, so that
the focus is thrown too far back, and it is corrected by wearing
spectacles sufficiently convex to supply the deficiency in the lens of
the eye.
An admirable example of temporary long-sightedness is familiar to every
diver, though he may be unconscious of its cause. Suppose that into very
clear water of some twelve feet in depth, a white object, say a common
jam-pot, is thrown, it can be clearly discerned from the shore,
unaltered in shape or size. But, when the diver searches for it, he sees
at first only something white, large, undefined, and wavering, and only
finds it resume its proportions as he approaches it. This phenomenon is
due to the pressure of the water upon the eyeball, which flattens it,
and so throws the focus too far back for a clear image. Nowadays this
defect is remedied by the use of very convex spectacles, so convex,
indeed, that, if worn in the air, they would render the wearer incapable
of seeing anything at more than an inch or so away from him. But, when
worn in the water, they only supply the deficiency of the compressed
eyeball, and so restore the focus to its proper position.
* * * * *
THOSE who suffer from short-sightedness can see with great distinctness
objects which are close at hand, but those at a little distance seem to
have no particular outline, and appear as if they were viewed through a
fog, thus causing a constant and almost painful strain on the eyes. The
cause of this defect is the too great convexity of the lens, which
therefore throws its focus short of the required spot. The means of
remedy are exactly opposite to those which are used for long-sighted
persons, a concave lens being placed in front of the eye, so as to throw
the focus farther back, and relieve the organ from the strain.
Although we have not yet invented a machine that can alter the focus at
will, we may take a hint from Nature. We have already seen how the
pressure of water upon the front of the eye lessens its convexity, and
makes it long-sighted. Consequently, if we could apply pressure round
it, we could make it more convex, and so neutralise the weight of the
water.
There is a wonderful piece of machinery in Nature which really does
perform this office, the eye, at the will of its owner, becoming either
telescopic or microscopic. This quality is very desirable in birds,
especially those which are predacious and of rapid flight, as they might
either fail to see their prey at a distance, or might dash themselves
against some obstacle when they were close upon it.
The eye of the Owl affords a beautiful example of machinery which
produces this effect, and the means which are used may be understood by
inspecting the accompanying illustration.
It will be seen that the eyeball is set in a framework composed of thin
bony plates, just like a glass in a telescope. When these plates are
relaxed, the whole eyeball is flattened, so as to enable the bird to see
an object at a very great distance. But, when they are contracted, they
render the whole eye globular in proportion to their pressure, and
enable the bird to see objects which are very close to it. In fact, the
eye becomes a telescope or microscope as needed.
Many reptiles possess this arrangement of bones, but the birds have even
a more delicate mode of obtaining the focus of the eye. This is by means
of a curious organ called, from its shape, the “pecten,” or comb, which
is placed in the vitreous humour at the back of the eye, and connected
with the optic nerve. It is a congeries of arteries and veins, so that
it can be rapidly enlarged by forcing blood into it, or diminished by
allowing the blood to withdraw.
As the liquid in which it rests is practically incompressible, it
follows that when the comb expands, it causes the chamber of the
vitreous fluid to expand, and so forces the lens forward. When, however,
the blood retires from the comb, the lens returns to its original place.
This, as the reader may have noticed, is the same principle as that
which is followed in altering the focus of a telescope in order to suit
the sight of different individuals. Perhaps a still better illustration
may be found in the coarse and fine adjustment of the microscope, the
former of which moves the whole tube, and may be compared to the bony
ring; while the latter causes one part to slide over the other, and is
analogous to the comb.
The movements of this organ are believed to be as involuntary as the
dilatation and contraction of the iris; but, whatever may be the case,
it is one of the most beautiful examples of natural mechanics, and far
surpasses the most delicate machine that can be made by man.
In the illustration of the microscope, which is to be found on page 286,
both these movements are given, the double vertical wheel being the
coarse movement, and the fine movement being supplied by the single
vertical wheel just above them.
* * * * *
WHILE we are on this subject, we may see how Art unintentionally copies
Nature, even in trivial details. Every one who is in the habit of using
optical instruments, more especially those who are forced to wear
spectacles, are aware of the necessity of keeping the glasses as clean
as possible, and, where the instruments are delicate, always have by
them a piece of clean wash-leather for the express purpose of wiping the
glasses.
Here, again, Nature has anticipated Art. In our own case, we have in the
human eye a good example of such natural mechanism, the eyelids being
formed quite as much for the purpose of washing the surface of the
eyeball as of excluding light.
Many animals are provided with a special apparatus for the purpose,
called the “nictitating membrane.” It is, in fact, a sort of inner or
supplementary eyelid, which can be drawn over the eye while the external
lids remain comparatively unmoved. It is very conspicuous in the owls,
and gives to those birds that almost comical look of perpetual blinking
with which we are so familiar.
THE STEREOSCOPE AND PSEUDOSCOPE.
Many persons have wondered how it happens that, as we have two eyes, we
do not see two images instead of one. Practically, this is always the
case, for the eyes, especially when they look on solid bodies, see two
different images, because they contemplate the object from different
points of sight.
This may be easily ascertained by looking at a given object first with
one eye, and then with the other, when it will be seen that the image
presented to the right eye is slightly different from that of the left
eye, but that the two can be combined into one by a very slight inward
movement of both eyes, and thus the effect of a solid body be produced.
Sometimes, when people are weak, and cannot control the united movement
of the eyes, not only two, but five or six images are at once presented
to the mind, and produce a strange sense of bewilderment and confusion.
[Illustration: COMBINATION OF HUMAN EYES.]
[Illustration: STEREOSCOPE.]
[Illustration: BINOCULAR MICROSCOPE.]
Painters are obliged to avail themselves of this peculiarity, and to
make allowances for the double vision. If they do not, the effect of the
painting is flat, and it appears as if the artist had only used one eye.
A good proof of this fact may be seen in Stereoscopic photographs,
especially of scenery. If each be viewed separately, it often appears
quite unintelligible, but, when they are combined by the instrument,
they seem to spring into life as it were, and appear solid enough to be
grasped.
Now, the Stereoscope is avowedly constructed on the same principle as
the double vision of the eye, so that when it applies itself to two
photographs of the same object which have been taken from different
points of view, it combines them, and gives them as solid an appearance
as if they were realities.
So wonderfully close is the representation, that the idea of a place
obtained by means of the combination of the photograph and Stereoscope
is quite as vivid and correct as if it had been gained by actual
observation.
The principle of the Stereoscope is now applied to the best microscopes,
and its value is incalculable, especially when low powers are used,
_i.e._ those of not less than half an inch focus. The real beauty of
many objects could never have been appreciated but for this discovery,
nor their true form defined.
On the left hand of the illustration is shown the combining power of the
eyes. Supposing the right eye only to be brought to bear upon the little
cylinder, only one side of it will be seen, and it looks nearly flat.
The same is the case with the left eye. But, when both eyes are used
together, both sides of the cylinder are presented to the mind, and thus
we get the effect of solidity.
The Stereoscope is so formed, by means of lenses, that the two figures
become combined into one, the rays of light being turned out of their
course by the arrangement of the glasses.
The Stereoscope, however, although a useful assistant to the vision, is
not necessary. It is perfectly possible to combine the two figures
without any stereoscope, and to do so merely by squinting, if we may so
call it, at the figures. The power of combination is gained with a very
little practice, and in a short time the observer will be capable of
producing stereoscopic effects without needing a Stereoscope. This
ability is very useful when inspecting photographs in a shop-window. Of
course the figures are not so much enlarged as they are with the
stereoscope, but they are nevertheless quite as clear and well defined.
* * * * *
THERE is an instrument called the Pseudoscope, which, as its name
imports, gives a false idea as to the nature of the object which is
viewed through it, converting hollow objects into solid, and _vice
versâ_. The following description of its effect is given by
Wheatstone:--
“When an observer looks with the pseudoscope at the interior of a cup or
basin, he not unfrequently sees it at first in its real form; but by
prolonging his gaze he will perceive the conversion within a few
minutes; and it is curious that, while this seems to take place quite
suddenly with some individuals, as if the basin were flexible, and were
suddenly turned inside out, it occurs more gradually with others, the
concavity slowly giving way to flatness, and the flatness progressively
rising into convexity.
“Not unfrequently, after the conversion has taken place, the natural
aspect of the object continues to intrude itself, sometimes suddenly,
sometimes gradually, and for a longer or shorter interval, when the
converse will again succeed it--as if the new visual impression could
not at once counteract the previous results of recent experience. At
last, however, the mind seems to accept the conversion without further
hesitation; and after this process has once been completely gone
through, the observer, on recurring to the same object, will not find it
possible to see it in any other than its converted form, unless the
interval should be long enough to have allowed him to forget its aspect.
“Vagaries, however, sometimes occur in these experiments of which it is
difficult to give any certain explanation, but which would be probably
found referable to the same general principle, if we were acquainted
with all the conditions of its operation.”
THE MULTIPLYING-GLASS.
Still more extraordinary examples of the combining power of vision
are to be found in the eyes of spiders and insects, more especially
when we compare them with the work of man. If we take a common
Multiplying-glass, such as is shown in the figure, and look at a flower
or other object through it, we see the object repeated as many times as
there are different foci of vision in the instrument.
[Illustration: EYES OF SPIDER.]
[Illustration: MULTIPLYING-GLASS.]
Now, taking for example the eyes of a Spider, it would be natural to
suppose that the same result would occur, especially as the foci of the
eyes point in different directions. The left-hand figure in the
illustration represents the eight eyes of one of our common Spiders,
belonging to the genus _Clubiona_, which may be found in almost any
outhouse, sitting in its curious web, and ready in a moment to run for
safety into its silken tunnel.
It will be seen that the foci of all the eyes are in different
directions, and so placed as to command a large radius. Observers have
remarked that the eyes are placed in Spiders so as to suit their habits.
“Those spiders,” writes Professor Owen, in his “Comparative Anatomy,”
“which hide in tubes, or lurk in obscure retreats, either underground or
in the holes or fissures of walls or rocks, from which they emerge only
to seize a passing prey, have their eyes aggregated in a close group in
the middle of the forehead, as in the Bird-spider, the _Clotho_, &c.
“The spiders which inhabit short tubes, terminated by a large web,
exposed to the open air, have the eyes separated and more spread upon
the front of the cephalothorax.
“Those spiders which rest in the centre of a free web, along which they
frequently traverse, have the eyes supported on slight prominences,
which permit a greater divergence of their axis; this structure is well
remarked in the genus _Thomisa_, the species of which live in ambuscade
in flowers.
“Lastly, the spiders called _Errantes_, or Wanderers, have their eyes
still more scattered, the lateral ones being placed at the margin of the
cephalothorax.”
Yet, although each eye produces a separate image, it is clear that upon
the mind of the Spider only a single idea can be impressed, for that
otherwise all would be confusion. There must, therefore, be some
mechanism in the structure of the eye, the nature of which we are not as
yet able to understand.
* * * * *
A STILL more remarkable instance of a natural Multiplying-glass may be
found in the eyes of many insects.
The form of multiplying-glass shown in the accompanying illustration is
probably familiar to most of my readers. It consists of a convex piece
of glass, cut into a number of facets, and showing in each facet a
distinct and separate image of the object to which it is directed. Now,
the compound eyes of insects are constructed on much the same
principle, except that the number of facets is infinitely more. Taking,
for example, the eyes of the Tortoise-shell Butterfly, we find that
there are about seventy thousand lenses or facets. Now, it is possible,
with care, to remove the eye from the insect, cleanse it, and arrange it
in ä microscope in such a way that objects can be seen through it. When
this is done, a separate image is seen in each facet, just as is the
case with the Multiplying-glass, only, as the facets are very much more
numerous, the effect is proportionately more striking.
[Illustration: INSECT EYE.]
[Illustration: TUMBLER.]
[Illustration: MULTIPLYING-GLASS.]
The reader may notice that the facets of the insect eye appear to be
hexagons as perfect as those of the honey-comb. This appearance is
probably due to the fact that each eye is covered with a convex plate of
glassy brightness and transparency, and that, when such objects are
viewed from the front, they appear to have hexagonal instead of rounded
outlines. A familiar example of this fact may be found in the glass
tumblers which are ornamented with rounded projections on their surface.
If a photograph of one of these tumblers be taken, the resemblance to
the hexagonal markings of the insect eye is so close that the tumbler
might easily be taken for the eye.
OPTICS.
CHAPTER II.
THE WATER TELESCOPE.--IRIS OF THE EYE.--MAGIC LANTERN.--THE
SPECTROSCOPE.--THE THAUMATROPE.
Limits to Sight in the Water.--Effect of a Ripple.--The Eyes under
Water.--The Water Telescope, its Structure and Mode of
Use.--Gyrinus, or Whirlwig-beetle, and its Double Set of Eyes.--The
Iris of the Eye, and its Double Set of Contractile
Fibres.--Cotterill’s Lock and its Structure.--The Magic Lantern and
its Principle.--Chinese Shadows.--Spectre of the Brocken.--An
Adventure in Wiltshire.--Effect of the Halo.--The
Spectroscope.--Its Structure explained.--A Star on fire.--Motes in
the Sunbeams.--Bessemer Steel made by aid of the
Spectroscope.--Absorption Bands.--Detection of Blood.--A Man’s Life
saved by the Spectroscope.--The Pocket Spectroscope.--The Rainbow,
Dewdrop, Soap-bubble, Opal, and Pearl.--The Thaumatrope.--Structure
of the Retina.--Complementary Colours.--The Zoetrope and
Chromatrope.--Wheel Animalcules and their Structure.--An Optical
Delusion.
THE WATER TELESCOPE.
Every one who has watched the movements of the various creatures which
live below the surface of the water is aware how entirely dependent he
is on the unruffled character of that surface. No matter how clear the
water may be, the least ruffling of the surface will effectually shut
out all sight:--
“But if a stone the gentle sea divide,
Swift rippling circles rush on every side,
And glimmering fragments of a broken sun,
Banks, trees, and skies in thick disorder run.”
And there is an end of the observations. If, however, the eyes can
penetrate below the surface, the ruffling is of little consequence, so
long as the water is clear. Consequently, whenever the top of the bank
is sufficiently near the water, it is possible to continue the
observations by lying down, and immersing the head above the eyes. This
plan, however, is not a very comfortable one, although I have often
followed it on a windy day when the surface was too ruffled to permit of
vision in any other way.
Still, there is an instrument by which it is possible to counteract the
ruffle of the surface, and to see objects with tolerable plainness. This
is called the Water Telescope, and it is of very simple construction.
Like the ordinary telescope, it consists of a tube, but, instead of the
convex and concave lenses of that instrument, it has only a single glass
at one end, and that glass is perfectly plane.
[Illustration: WHIRLWIG-BEETLE.]
[Illustration: WATER TELESCOPE.]
When used, the eye is applied to the open end, and the glazed end
lowered into the water. The sight is then undisturbed by the ripple, and
the effect is the same as if the eyes themselves were lowered beneath
the surface.
It is much used in looking for shells, sea-urchins, and other creatures
which live in the bed of the sea.
* * * * *
IN the insect world we have an example of a natural Water Telescope. I
do not say that the inventor of the Water Telescope took his idea from
the insect, but the reader will see that he might very well have done
so.
There are sundry little beetles popularly called Whirlwigs or
Whirligigs, and scientifically known by the name of _Gyrinus_. All these
names allude to the insect’s habit of whirling about on the surface of
the water, with a movement which seems ceaseless and untiring. Allusion
has already been made to the Whirlwigs on page 22.
Their object in their perpetual waltz is not so much amusement as food,
which chiefly consists of the tiny insects which fall into the water.
Now, in order to enable it to see both above and below the water, a
peculiar structure is required. Generally the insects possess one pair
of compound eyes, each group being set on the sides of the head. In the
Gyrinus, however, there are two sets of these eyes, one pair being on
the upper surface of the head, and the other on the lower surface. Thus,
while it can use the upper pair for seeing objects which are out of the
water, the lower pair of eyes, which are submerged, act the part of the
Water Telescope, and enable it to see objects that are below the
surface. Were it not for this precaution, even the ripples which it
makes by its own rapid progress would prevent it from seeing.
THE IRIS OF THE EYE.
[Illustration: IRIS OF HUMAN EVE.]
[Illustration: COTTERILL’S LOCK.]
I have often wondered, when contemplating the astonishing mechanism by
which the Iris of the Eye is able to contract or enlarge the pupil
according to the amount of light, whether any similar mechanism would be
used in Art. As anatomists know, the Iris is composed of two layers. One
consists of radiating fibres, which serve to enlarge the pupil, while
the other layer surrounds the latter, and by its elasticity serves to
contract it. As any one may see by looking in a mirror and shifting the
light, the pupil is perpetually changing its diameter, but always
retaining its circular shape. A glance at the illustration will show the
two layers, and aid the reader in understanding the mode in which they
work.
Some years ago, while looking at the account given by Mr. J. Price of a
lock invented by Mr. Cotterill, I saw at once that the inventor, whether
consciously or not, had followed the mechanism of the eye, as far as
metal could be expected to imitate animal fibre.
In the very centre of the lock there is a small circular opening,
resembling the pupil of the eye, and serving to admit the key, just as
the pupil admits light. Around this pupil, if we may so call it, are
ranged some twenty thin steel slides which move in channels, up and down
which they slide. Round the circumference of the lock are a
corresponding number of spiral springs, each of which presses on the
base of a slide, and forces it towards the centre.
The reader will now see that the radiating slides of the lock represent
the radiating fibres of the iris, and that the spiral springs represent
the circular fibres. Both perform the same office, the steel slides
regulating the size of the aperture, and the spiral springs pressing
them all towards the centre. The key of the lock answers the same
purpose as does light in the eye, which by its mysterious pressure
enlarges or contracts the pupil.
This is not the place to describe this very ingenious lock in detail,
but I may state that it has never been picked. Even Mr. Hobbs, who tried
it for twenty-four hours, gave it up, and, when he saw the interior
mechanism, said that if he had tried for a month he should have made no
progress. This is an unconscious testimony to the wisdom of following
Nature in Art.
THE MAGIC LANTERN.
We are all familiar with the Magic Lantern, whether it may take the form
of the mere child’s toy, be developed into Dissolving Views, or throw
black shadows on a curtain, in which case it is called by the name of
Chinese Shadows. In all these cases the principle is the same. First we
have a light behind the object whose reflection is to be seen. Next we
have the object itself, and lastly the surface upon which it is
reflected. As to the variety of mirrors, lamps, and lenses which are
used to produce different effects, we may put them aside as foreign to
our present purpose.
[Illustration: MAGIC LANTERN.]
Generally the object is reflected upon a white curtain or sheet, but
sometimes, when a specially weird-like effect is needed, a cloud of
thick smoke takes the place of the sheet, and upon it the reflection is
shown, as seen in the accompanying illustration.
* * * * *
NATURE has her Magic Lanterns as well as Art, and wonderful things they
are sometimes, the well-known Brocken Spectre being an excellent
example. It is not, however, necessary to visit the Brocken in order to
see this apparition, for I have seen it in perfection in England.
Many years ago, when living in Wiltshire, I went before daybreak to the
top of a very high conical hill. The morning mist was so thick that I
could scarcely see my way up the hill. When I reached the summit, I
stood there for some time, trying to see the landscape, but the mist was
so thick that I could barely tell the points of the horizon by the
brighter look cast by the coming Day in the east.
I was looking westward, when suddenly the sun rose behind me, and I saw
the Brocken Spectre as I have sketched it in the accompanying
illustration. It was a gigantic shadow of myself, projected on the mist,
just as a Magic Lantern projects the image on a sheet or a smoke-cloud.
Of course my gestures were repeated, and it really looked almost awful
to see this gigantic spectral figure set in the mist.
Perhaps the most extraordinary part of it was the enormous halo of
rainbow colours round the head. No matter where I moved, the halo
surrounded the head of the image, its colours being comparatively bright
near the centre, and becoming gradually paler towards the circumference.
Another point about this natural Magic Lantern ought to be mentioned.
[Illustration: BROCKEN SPECTRE.]
Wishing to show a friend the extraordinary sight of a Brocken Spectre, I
took him up the hill on a misty day like that which has been briefly
described. According to surmise, two spectres appeared instead of one,
but the halo was not doubled as well as the shadow. I could see my
friend’s shadow, and he could see mine. But, although the halo was as
bright as before, each of us could only see it encircling his own head.
We stood as close to each other as we could, we moved apart as far as
the nearly conical top of the hill would allow, and in both cases each
of us could only see his own halo.
Perhaps the reader may remember the wonderful spectre-scene drawn by Mr.
Whymper, and viewed from the Matterhorn just after the accident which
had killed several of his companions in the ascent of the hitherto
impregnable peak. In the mist there suddenly appeared three vast dark
crosses enclosed in an oval. Considering the highly-strung nerves of the
survivors, it was no wonder that they were all shaken by such an
appearance, and that the guides were for a time too frightened to
proceed.
THE SPECTROSCOPE.
Next we come to one of the most astonishing and beautiful optical
instruments ever made by the hand of man. It is called the Spectroscope,
because it deals with a certain arrangement of rays which is called a
“spectrum.” Many years ago Newton discovered the cause of the lovely
colours which deck the rainbow, and the fact that, by passing a ray of
white light through a prism, it was decomposed into seven colours, which
invariably came in the following order--Red, Orange, Yellow, Green,
Blue, Indigo, and Violet. He also discovered that, by looking at that
coloured band through another prism arranged in a different manner, the
decomposed rays were again brought together, and white light was the
result.
Newton had thrown the light on the prism through a round hole, but some
time afterwards Dr. Wollaston employed a narrow slit for the purpose,
and then found that the spectrum was traversed by dark lines which never
changed their places. On these lines depend all the discoveries that
have been made by the aid of the Spectroscope. The chief of them are
designated by the letters of the alphabet. (See page 300.)
It was soon found out that if burning gases were viewed with the
Spectroscope, lines were still seen, but they were bright instead of
dark, and that they invariably occupied the place of one or more of the
dark lines shown by the spectrum of sunlight. Then it was discovered
that these burning gases absorbed or stopped out the light in the solar
spectrum, and from that moment the science rapidly advanced.
At the present day the Spectroscope not only determines the metals which
exist in the sun, but also those of the fixed stars. It even analyzes
the constitution of double stars, and shows the reason why one star
should be red and the other green.
One of the most astonishing discoveries in astronomy was due to the
Spectroscope.
During the month of May, 1866, one of the stars in the Northern Crown
(_Corona Borealis_) was seen to undergo a rapid change. It was
originally one of the tenth magnitude, but in a short time increased in
size and brilliancy until it nearly equalled Sirius, Capella, or Vega.
It remained bright for some time, and then rapidly faded until it
resumed its former size.
How this change was effected we never should have known but for the
Spectroscope. No sooner, however, was this instrument pointed at the
star than there appeared in the spectrum the three well-known
lines--red, green, and violet--which denote burning hydrogen. There was
no doubt on the matter, and the Spectroscope showed us that we were
witnessing a conflagration the like of which was never seen or scarcely
imagined.
[Illustration: RAINBOW.]
Supposing our sun, which is known to be one of the stars, and about
which there are vast volumes of hydrogen gas, were to blaze out in a
similar manner, the result would be that the whole of the planets would
be consumed in a few seconds, and converted into gases. In an instant
every living thing would be swept off the surface of the earth by this
fearful heat, and, as Mr. Roscoe says, “our solid globe would be
dissipated in vapour almost as soon as drops of water in a furnace.” So,
as Mr. Huggins observes, the old nursery rhyme,--
“Twinkle, twinkle, little star,
How I wonder what you are,”--
is no longer tenable, for we really do know the composition of the
stars.
The Spectroscope not only tells us the substance of which the sun and
the most distant stars are made, but gives us the same information about
the “gay motes that people the sunbeam.” It tells us that they are
common salt in very minute particles. They have been dashed into the air
by the winds as spray, and then dispersed over the whole globe. This is
one reason why we have so much salt in our bodies, and why the blood and
the tears are so salt.
* * * * *
IT is also applied to the arts. The well-known Bessemer process consists
in pouring melted iron into a peculiarly shaped vessel called a
“converter,” and blowing air through it for the purpose of burning out
the carbon. From the mouth of the converter issues a volume of
magnificent flames, and at a certain moment the skilled workman who
directs the process inverts the vessel and pours out the steel. A very
few seconds too soon or too late would spoil the whole of the metal, in
the former case it being simply brittle cast-iron; and, in the second,
becoming so thick that it could not be poured out.
Only a few workmen could judge rightly the exact point at which to shut
off the air-blast. They watched the flame, and by some change in it, too
slight to be noticed by any except experienced eyes, knew the moment
when the iron was converted into steel.
Such men could, of course, demand any wages they liked, and, by
striking, stop the whole works. The Spectroscope, however, performed
this delicate discrimination far better than the best workman. When
directed to the flame, the bright lines indicating carbon are seen in
the spectrum. When the blast has continued for some twenty minutes, the
carbon lines suddenly disappear, showing that the carbon has been burned
out, and giving to the workman the signal to shut off the air-blast.
* * * * *
ANOTHER discovery was, that liquids gave dark lines, technically termed
absorption bands, of different widths and in different parts of the
spectrum. Even liquids which had no perceptible colour threw bands as
bold as those which were coloured, while coloured liquids threw totally
different bands, irrespectively of their own colour.
For example, the green colouring matter of leaves, called chlorophyll,
throws a single broad band on the extreme left--_i.e._ across the red
part of the spectrum--so far back, indeed, that it is not easily seen at
first.
Then, suppose that we make some pale solutions of red substances, such
as carmine, magenta dye, port wine, logwood, permanganate of potash, and
blood, it is possible to have them so exactly resembling each other that
not even the microscope can discriminate between them; yet the
Spectroscope instantly detects the colouring matter of each solution.
[Illustration: SPECTRUM OF SUNLIGHT, OR SOLAR SPECTRUM.]
[Illustration: SPECTRUM OF BLOOD.]
The instrument is, therefore, invaluable in detecting adulterations of
wine. For example, supposing that red wine is suspected of owing its
redness to logwood, and not to the genuine grape, a drop is mixed with
water and viewed through the Spectroscope, which instantly tells whether
the colouring matter is grape or logwood. And as, by photography, the
spectrum can be exactly copied, an indelible record is procured of the
true nature of the object.
So marvellously delicate is the instrument with regard to blood, that it
detects the thousandth part of a grain of colouring matter in a
blood-stain.
If upon the spectrum were printed the word BLOOD in the largest and
blackest of capitals, it could not be more legible to an ordinary reader
than are the two blood-bands to the eye of a spectroscopist. There is
nothing like them in nature, and whether it be by association of ideas,
or by absolute fact, these two bars have a strangely menacing look about
them. Not only that, but if the blood should be that of a person
suffocated with carbonic acid gas, the Spectroscope will say so.
Some years ago a man owed his life to the Spectroscope. A mysterious
murder had been committed, and the police had arrested a man who was
found near the spot. He could give no intelligible account of himself,
and the sleeves of his coat and a part of his waistcoat were deeply
stained with a red substance just like clotted blood. A piece of each
garment was cut off and given to a well-known spectroscopist, who tried
the red matter in the instrument, and at once declared it not to be
blood. What it was he had not time to ascertain, so he sent it to a
brother in science, who, after examination, pronounced it to be red gum.
By degrees, the man, who had been intoxicated when arrested, stated that
he had been to see a friend who was a journeyman hatter. It was then
found that he had been leaning on the workman’s board, and so had
carried off some of the gummastic with which hats are stiffened. Had it
not been for the infallible Spectroscope, the man might have lost his
life.
Thus we see that the Spectroscope is the elephant’s trunk of optics,
equally fitted for the greatest and smallest, the farthest and nearest,
of objects. It is equally at home in earth and sky. When attached to the
telescope, it reveals the constituents of the stars, and, when affixed
to the microscope, it shows us the colouring matter of a green leaf. It
produces the best steel, and detects adulteration in wine. And, lastly,
as we have seen, it turns lawyer, and settles the evidence by which the
life of a man is lost or saved. It can determine the purity of the
smallest coinage, and tell us why a star changes in magnitude.
Yet all these wondrous revelations are made by a few prisms and a
magnifying-glass. I possess a Spectroscope, made and presented to me by
Mr. J. Browning, the celebrated optician. This astonishing instrument is
only three inches long, and half an inch in diameter, so that it can be
carried in the waistcoat pocket. I always keep mine in a finger of a
white kid glove, which is amply sufficient for it. Yet it gives the
spectrum of the sun with its principal lines, will detect the fraudulent
wine merchant, and could have decided whether the accused man should be
acquitted or hanged.
* * * * *
MARVELLOUS and mighty as is this engine, it lay concealed in Nature ever
since the sun’s rays shone upon earth and a drop of water existed. The
Rainbow is nothing but a vast spectrum, a transverse slice of which
would be a good representation of the coloured band which is shown in
the instrument. It is prefigured in the ever-shifting rainbows of the
water-fall and fountain, which latter may even be seen in the fountains
of Trafalgar Square, while at the Crystal Palace their beauty has long
been noticed.
There is not a dewdrop which is not a miniature Spectroscope, as it
glitters with its wondrous iridescence in the rays of the rising sun;
there is not an opal with its shifting hues, nor the splendour of the
soap-bubble, nor the nacre of the common river mussel or the ormer
shell, which does not owe its beauty to the same principles which govern
the Spectroscope. Every green leaf, and blue or pink or yellow petal,
every varying tint of the mackerel sky, every blaze of sunset and
bluegrey of sunrise, owes its beauty to those wondrous laws of light
which had been hidden for so many centuries, until they were unveiled by
the simple prism of the Spectroscope. As in so many instances, the
revelation lay concealed until the coming of the revealer, whose
inspired hand raised the dark veil of centuries.
THE THAUMATROPE.
Middle-aged persons will recollect that since the days of their
childhood a great variety of optical apparatus has been invented ending
in the word “trope.” This is a Greek word, signifying to turn, and is
given to the instruments because they revolve.
All these toys--and they may some day become more than toys--depend on a
curious property of the human eye. The reader will remember that in the
description of the human eye, as compared with the camera obscura as
applied to photography, it was mentioned that the image was thrown from
the front to the back, and in the one case was received on a naturally
sensitive membrane, and in the other on a film rendered artificially
sensitive by chemical means. This membrane is called the “retina,”
because it not only receives the impression, but retains it for some
little time after the object is removed. It has been calculated that the
duration of the image is about the eighth part of a second.
Thus the eyelids are perpetually and unconsciously closing and opening
with a rapid movement, popularly called “winking.” This movement is for
the purpose of cleansing the eyeball, and, were it not for the
image-retaining power of the retina, we should pass a considerable part
of our time in absolute darkness. As it is, the impression of external
objects on the retina lasts longer than the time occupied in winking,
and, in consequence, we are not conscious that any interval of darkness
has elapsed.
Again, when we have been looking steadfastly at an object, and then move
our eyes, the image of that object is seen in the new focus; and it is
worthy of notice that such object is always seen in its “complementary”
colour. For example, if we have been looking at a scarlet spot, and
suddenly move our eyes, we shall see a spot exactly similar in size and
shape, but of green.
I well remember that when I was a boy I was reading with almost feverish
anxiety the green handbill of a travelling circus, to which I hoped that
I might be allowed to attend. Having finished it, I asked for some
note-paper, for the purpose of putting my request in writing, but, to my
astonishment, mixed, perhaps, with a little irritation, all the paper
supplied to me was of a bright pink. For a time no arguments could
convince me that the paper was really white, until by degrees the pink
hue became paler and paler, and the paper assumed its normal whiteness.
The fact was, that the eye had become saturated with the green--_i.e._
the blue and yellow rays--and could see nothing but their complementary
colour, which was pink.
A good example of this property may be found in a lighted stick, which,
if rapidly whirled round, appears to form a continuous circle of fire.
The reason of this is, that the impression made on the retina by the
fiery point does not cease until the stick has again come round in its
course.
Then there are those well-known chromatic tops, in which are inserted
pieces of bent wire. When the top is spun these pieces of wire assume
exactly the appearance of transparent jugs, vases, glasses, and similar
articles. A very pretty illustration of this principle is given by a
little machine, which is made to revolve rapidly by means of a
multiplying wheel.
Upon its surface are fixed little pins, with polished globular steel
heads, and, when the handle is turned, these heads form the most
beautiful and intricate figures with exact accuracy.
Another toy, called the Thaumatrope, or Wonder-turner, is equally
ingenious and beautiful, and is sufficiently simple to be made by any
one with a slight knowledge of drawing. A disc of white cardboard is
cut, and upon each side of it is portrayed some object. If the disc be
caused to revolve rapidly, these two subjects will be seen at the same
time, the image of each being held on the retina long enough to allow
the other to take its place.
Some very beautiful combinations may be made by means of this
instrument. For example, a horse may be on one side, and a man on the
other, and, by spinning the disc, the man will be seen mounted on the
horse. Then we may have a boat on one side, and a rower with his oars on
the other. Similarly a mouse can be put into a trap, or a bird into a
cage.
The reader must remember that these subjects must be drawn as if they
were upside down with regard to each other, so that the man who is to
ride the horse is drawn as if he were standing on his head, and the
mouse which is to enter the trap looks as if it were lying on its back.
The most simple manner of spinning the disc is by means of two threads,
each being inserted near the edge of the disc, and exactly opposite each
other.
A very ingenious modification of the Thaumatrope is made by inserting at
one side of the disc two strings, of which one is elastic. It is
evident, then, that by lengthening or shortening the elastic string, the
axis can be changed, and the objects on the opposite sides placed in
positions relatively different from each other. Thus the jockey may be
made to jump on and off his horse, the bird to go in and out of its
cage, the mouse to enter the trap, and so on. This simple invention
allows of infinite combinations, so that a tree may be made to sprout, a
man to move his limbs, and a bird to flap its wings. It was invented, I
believe, by Dr. Paris, author of “Philosophy in Sport made Science in
Earnest.”
On the right hand of the illustration are seen three figures, each
representing a means of obtaining an ocular delusion through the
principle of which we are now treating.
The lower figure is called the Zoetrope, or Wheel of Life. As the reader
may see, it consists of a hollow cylinder, revolving on a centre, and
having within it a series of figures. When the wheel revolves, and the
figures are viewed through the slits, each figure seems to be in
lifelike motion, whence the name of Zoetrope. In the present case the
figures are those of boys jumping over posts.
[Illustration:
WHEEL ANIMALCULE.
PHANTASMASCOPE.
CHROMATROPE.
ZOETROPE.]
The mode in which this effect is produced is as follows:--Suppose that a
boy were really to jump over a post, he would go through a series of
motions, and his body be placed in a certain series of positions, before
he cleared the post. Supposing, then, that several points were chosen in
his course, and his body drawn as it would appear at these points, and
the drawings placed in their proper order in the Zoetrope, it is evident
that the figures must appear in movement. Before the retina loses the
image of the boy standing in front of the post, it takes in that of the
boy stooping, with his hands on the top of the post, and so on until he
has reached the ground on the opposite side.
Another mode of producing the same effect, called the Phantasmascope, is
seen above the zoetrope. In this case the images are placed on the
inside of the disc, which is held opposite a mirror, and the figures
viewed through the slits.
The last of these figures is the rather complicated one, like the back
of an “engine-turned” watch. This is called the Chromatrope, or Wheel of
Colour, and is always a favourite object in a magic lantern. It consists
of two circular plates of glass, one upon the other, and painted in
variously coloured curved lines, as seen in the illustration. When the
image is thrown upon a screen, and the glass plates turned in opposite
directions, a most singular and beautiful effect is produced. The lines,
unless the eye follows them very closely, disappear, and torrents of
coloured spots seem to pour from the centre to the circumference, or
_vice versâ_, according to the direction in which the glass wheels are
turned. So perfect is the illusion, that it is almost impossible to
believe that the movement is only circular, and not spiral.
* * * * *
NOW we will pass from Art to Nature. The figure on the left hand of the
same illustration represents part of one of the Wheel Animalcules, so
called because they look exactly as if the fore-part of their bodies
were furnished with two delicate wheels, running rapidly round, and
evidently moving or stopping at the pleasure of the owner.
Soon after the powers of the microscope became known, these
Wheel-bearers were discovered, and for a long time they were thought to
have a pair of veritable revolving wheels upon their heads. They were
naturally held in high estimation, as, although almost every kind of
lever can be found in the animal world, a revolving wheel had never been
seen. However, as the defining powers of the microscope improved, the
so-called wheels were found not to be wheels at all, but stationary
organs, and that their apparent revolution was nothing but an optical
delusion.
The wheels are, in fact, two discs, around the edges of which are set
certain hair-like appendages, called “cilia,” from a Latin word
signifying the eyelashes. Each of the cilia has an independent motion of
its own, and, as they bend in rapid and regular succession, they produce
an effect on the eye similar to that of a revolving body. As for the
animal itself, they produce a double effect, either acting as paddles,
and forcing the animal through the water, or, when it is affixed to some
object, causing a current which drives into its mouth the minute beings
on which it feeds.
The particular species of Wheel-hearer whose mouth is here shown is
called scientifically _Limnias ceratophylli_. It derives the latter name
from the fact that it is mostly found on the submerged stems and leaves
of the Hornwort (_Ceratophyllum_), which is very common in ponds and
slow streams. The creature is, however, to be found on the water-growing
plants, and Mr. Gosse, in his “Evenings with the Microscope,” gives a
very full and graphic account of itself and its habits.
He specially mentions the use of the wheels, and, by dissolving a little
carmine in the water, had the pleasure of seeing the coloured granules
swept into the mouth by the current caused by the cilia through the
jaws, and so into the stomach.
USEFUL ARTS.
CHAPTER I.
PRIMITIVE MAN AND HIS NEEDS.--EARTHENWARE.--BALL-AND-SOCKET
JOINT.--TOGGLE OR KNEE JOINT.
Contrast between Savagery and Civilisation.--Manufacture of
Weapons.--Earthenware of Art.--Sun-baked Vessels.--Earthenware of
Nature.--Nest of Pied Grallina.--Analogy with the Babylonish
Brick.--Nest of the Oven-bird.--A partitioned Vessel.--Necked
earthenware Vessels.--Nests of Eumenes, Trypoxylon, and
Pelopœus.--Proof of Reason in Insects.--The Ball-and-socket
Joint.--“Bull’s-eye” of Microscope.--The human
Thigh-bone.--Vertebræ of the Serpents and their Structure.--The
Sea-urchin and its Spines.--Legs and Antennæ of Insects.--The
Toggle or Knee Joint, and its Use in the Arts.--The hand
Printing-press and the Toggle-joint.--The human Leg and Arm.--Power
of the natural Toggle-joint.--Fencing and Boxing.--Heads of
Carriages.--“Bowsing” of Ropes.--Leaf-rolling Caterpillars.
In the primitive ages of Man the aids to civilisation were very few and
very rude. Some of them, especially those which relate to hunting and
war, have already been mentioned, and we now have to deal with some of
those which bear upon domestic life.
Here we are in some little difficulty, for it is not very easy to draw
the line where domestic life begins, or the mode in which it shall be
defined. We may at all events connect domestic life with a residence of
some sort, and may, in consequence, neglect all such primitive savages
as need no domestic implements.
Such, for example, are the few surviving Bosjesmans of Southern Africa,
not one of whom ever made a tool or an implement, or looked beyond the
present day. The genuine Bosjesman can make a bow and poison his arrows,
and he can light a fire; but there his civilisation ends. He cannot look
beyond the present hour, he has not the faintest notion of making a
provision for the future, nor did his wildest imagination ever compass
the idea of a pot or a pan.
He kills his prey, and, if hunger be very pressing, he will eat it at
once without waiting for the tedious ceremony of cooking; or at the best
will just throw the meat upon the fire, tear it to pieces with his
teeth, and swallow it when it is nothing but a mass of bleeding flesh,
charred on the outside, and absolutely raw within. The Bosjesman has not
even a tent which he can call his own, any bush or hole in the ground
answering for a house as long as he wants it, and then being exchanged
for another.
As far as we know, the only trace of civilisation in the Bosjesman is
his manufacture of weapons, and even his bow and arrows are of the
rudest and clumsiest forms. Nor is it likely that he will ever advance
any further; for, as is the wont of all savage tribes, he is
disappearing fast before the presence of superior races, and will
shortly be as extinct as the Tasmanians, the last of whom died only a
few years ago.
EARTHENWARE.
The advent of real civilisation seems to depend largely upon the
construction, not of weapons, but utensils, and the most useful of these
are intended either for the preparation or the preservation of food.
That such vessels should be made of earth is evident enough, and it is
worthy of remark that the rude earthenware pot of the naked savage and
the delicate china of Sèvres should both be products of the earth, and
yet be examples of the opposite ends of civilisation.
The most primitive earthenware vessels were simply baked in the rays of
the sun, the use of fire for hardening them being of later date. Rude
and simple as they are, some of these vessels possess tolerable
strength, and can answer every purpose for which they are intended. I
possess several pots made by the aborigines of the Essequibo district.
They are very thick and heavy in proportion to their dimensions, and are
still so fragile that I have been obliged to bind them with string
whenever they are moved.
Simple as they are, however, they are pleasing to the eye, chiefly, I
presume, because they are made for a definite office, and fulfil it,
and have no pretence about them. Then, as they are moulded by hand
alone, without any assistance from machinery of any kind, even a wheel,
the individuality of the maker is stamped upon them, and no two are
exactly alike either in form, colour, or ornament. A couple of these
rude vases are to be seen on the right hand of the accompanying
illustration.
* * * * *
ON the left hand of the same illustration are shown two examples of
earthenware vessels made by birds, which are nearly, if not quite, as
good as those made by the hands of civilised man.
The upper figure represents the nest of the Pied Grallina (_Grallina
Australis_), a bird which, as its specific name implies, is a native of
Australia.
[Illustration:
NEST OF PIED GRALLINA.
NEST OF OVEN-BIRD.
PRIMITIVE EARTHENWARE.]
This nest is formed chiefly of clay, but a quantity of dried grass is
always mixed with it, and serves to bind it together. If one of these
nests be broken up, and compared with the bricks of which ancient
Babylon was built, it will be found that they are almost identical in
material, and that both are merely baked in the sun. In form it so
closely resembles an Essequibo jar in my possession, that if it were
removed from the branch, and similarly coloured, it would not be easy to
distinguish the one from the other.
* * * * *
BELOW this is the nest of the Oven-bird of South America (_Furnarius
fuliginosus_), a bird allied to our common creeper. The drawing was
taken from a specimen in the British Museum.
Like the nest of the Grallina, it is placed upon some horizontal bough,
and fixed so firmly that it cannot fall except by being broken to
pieces. Not being afraid of man, the Oven-bird often chooses a beam in
some outhouse for a resting-place, and has been known to build even on
the top of palings. As may be seen by reference to the illustration, the
nest is a very conspicuous one, and concealment is almost impossible.
As in the Grallina nest, the material is remarkably hard and firm, as
indeed is necessary, to allow it to withstand the effects of the
rain-torrents which fall during the wet seasons of the year.
There is a curious analogy in this nest with many articles of
earthenware. Not only among ourselves, but among uncivilised races,
earthenware vessels are constructed with partitions, so as to divide one
portion from another. If one of these nests be cut open, it will be
found to have a sort of partition wall across the interior, rising
nearly to the top of the dome, and so dividing it into two parts. The
wall also answers another purpose--_i.e._ that of strengthening the
entire structure. Within the inner chamber is the real nest, which is
lined with a thick layer of feathers, the outer chamber being bare, and,
as it is thought, being occupied by the male.
* * * * *
WE now come to pottery of a more elaborate shape. Both in the Grallina
nest and the earthen pot of the Essequibo Indian we have a vessel with a
mouth nearly as wide as its greatest diameter, and with a lip which is
very slightly turned over. There are, however, many varieties of pottery
in which the neck is narrow and long, and the lip is boldly formed. Some
examples of this form are given on the right hand of the accompanying
illustration.
* * * * *
ON the left hand are shown some nests of a solitary wasp belonging to
the genus Eumenes. It is a British insect, but seems to have been little
noticed, except by professed entomologists.
It especially haunts heather, and affixes to the stems of the plant its
little globular nests, which are made of mud, and shaped as seen in the
illustration. Perhaps some of my readers may have seen the “Napier
Coffee Machine,” which draws the coffee into a glass globe furnished
with a short neck. The globe is shaped exactly like the nest of our
Eumenes, and, when I first saw one, I could not remember why its shape
was so familiar to me.
As is the case with the birds’ nests which have been mentioned, the mud
of which the walls are built is of a most tenacious character, and, when
dried in the sun, can resist the heaviest rain. The cells are intended
as rearing-places for the young, only a single egg being placed in each
cell, which is then stocked with small caterpillars by way of food.
* * * * *
[Illustration: NESTS OF EUMENES.]
[Illustration: ANCIENT NECKED POTTERY.]
There is a South American insect also belonging to the solitary wasps,
and remarkable for building a round nest exactly similar in material,
and nearly identical in shape, with that of the Eumenes. Its scientific
title is _Trypoxylon aurifrons_. The nest of this insect has a much
wider mouth than that of the Eumenes, and exactly resembles the upper
left-hand jar in the illustration.
* * * * *
ANOTHER South American solitary wasp, belonging to the genus
Pelopœus, makes nests of similar material, but nearly cylindrical in
shape instead of globular. The nest is built up of successive rings of
moistened and well-kneaded clay, exactly as human houses are built by
bricklayers. Indeed, the process of making a Pelopœus’ nest has been
happily compared to that of building a circular chimney.
I may as well mention here that the name Pelopœus is formed from a
Greek word signifying mud, and that the entire word may be translated as
“mud-worker.”
As a proof that these insects possess reason as well as instinct, Mr.
Gosse mentions that one of them, instead of making her nest for herself,
utilised an empty bottle, and, after storing it with spiders, stopped up
the mouth with clay. Finding, after an absence of a few days, that the
nest had been disturbed, she removed the spiders, inserted a fresh
supply, and then closed the mouth as before.
BALL-AND-SOCKET JOINT.
We will now see how some of the most useful mechanical inventions have
had their prototypes in Nature.
There is, for example, the well-known “Ball-and-socket joint,” without
which many of our instruments, especially those devoted to optical
purposes, would be impracticable.
[Illustration: HIP-JOINT.]
[Illustration: SPINES OF SEA-URCHIN. VERTEBRÆ OF SNAKE.]
[Illustration: BALL-AND-SOCKET JOINT OF MICROSCOPE.]
The figure on the right hand of the illustration represents the
“bull’s-eye” of my own microscope. It will be seen that there is a ball
half sunk in a cup, so that it can be turned in any direction. In point
of fact, the upper part of the ball is nearly concealed by another cup,
but, in order to show the structure, the upper cup has been removed. Who
was the inventor of the ball-and-socket joint I do not know, but I have
little doubt that he must have had in his mind many natural examples of
this joint, three of which are represented in the illustration.
* * * * *
ON the left hand are seen the upper part of the human thigh-bone and
that part of the hip-bone into which it fits.
The reader will see that at its upper end the bone takes rather a sharp
turn, and is then modified into a ball. This ball fits into a
corresponding socket, technically named the “acetabulum,” and is thereby
endowed with freedom of motion in almost every direction. Generally we
do not practise our limbs sufficiently to develop that full freedom, but
those who have seen any good professional acrobats must have been struck
with the wonderful mobility of which the human body is capable.
The socket is not a deep one, but dislocation of the hip is exceedingly
rare, the bone being held in its place by three powers. The first is due
to a short ligament, which, however, does not always exist, but, when it
is present, is useful in retaining the bone in its place. Then there is
the contractile power of the thigh muscles, which are always forcing the
ball into the socket. Lastly, there is the pressure of the atmosphere, a
force which is seldom taken into consideration, but which has great
influence on many parts of the human frame. This part of the subject
will be resumed when we come to treat of Atmospheric Pressure.
The arms are jointed to the shoulder-blades in a very similar manner,
the upper arm-bone, or “humerus,” being furnished with a rounded end,
and fitting into a cup-like cavity in the shoulder-blade, or “scapula.”
This formation can easily be seen by separating the different bones of a
shoulder of mutton.
* * * * *
AT the bottom of the illustration are given two vertebræ of a snake,
separated in order to show their structure. It will be seen that each
joint has a ball in front and a socket behind, thus giving the creature
that wonderful flexibility which is quite proverbial, and without which
it could not seize its prey.
The following eloquent passage is taken from Professor Owen’s work
entitled “The Skeleton and the Teeth:”--
“Serpents have been regarded as animals degraded from a higher type, but
their whole organization, and especially their bony structure,
demonstrate that their parts are as exquisitely adjusted to the form of
their whole, and to their habits and sphere of life, as is the
organization of any animal which we call superior to them.
“It is true that the serpent has no limbs, yet it can outclimb the
monkey, outswim the fish, outleap the Jerboa, and, suddenly loosening
the coils of its crouching spiral, it can spring into the air and seize
the bird upon the wing: all these creatures have been observed to fall
its prey.
“The serpent has neither hands nor talons, yet it can outwrestle the
athlete, and crush the tiger in the embrace of its ponderous overlapping
folds. Instead of licking up its food as it glides along, the serpent
uplifts its crushed prey, and presents it, grasped in the death-coil as
in hand, to its slimy, gaping mouth.
“It is truly wonderful to see the work of hands, feet, and fins
performed by a modification of the vertebral column--by a multiplication
of its segments with mobility of its ribs. But the vertebræ are
especially modified, as we have seen, to compensate, by the strength of
their numerous articulations, for the weakness of their manifold
repetition, and the consequent elongation of the slender column.
“As serpents move chiefly on the surface of the earth, their danger is
greatest from pressure and blows from above; all the joints are
fashioned accordingly to resist yielding, and sustain pressure in a
vertical direction; there is no natural undulation of the body upwards
and downwards--it is permitted only from side to side. So closely and
compactly do the ten pairs of joints between each of the two hundred or
three hundred vertebræ fit together, that even in the relaxed and dead
state the body cannot be twisted except in a series of side coils.”
* * * * *
THE upper right-hand figure represents a portion of the shell of an
Echinus, or Sea-urchin, together with two of the spikes.
The reader will remember that in the description of the Heart-urchin,
and the mode in which it dug its way into the sand, the peculiar
mobility of the spines was mentioned. How that mobility is produced we
shall now see.
If a living Sea-urchin can be procured, and placed in a glass vessel
filled with sea-water, it will at once be seen that its surface is
thickly covered with spines. In some species these spines are as thick
as ordinary drawing pencils; but in most of those which are found on our
shores they are very slight, and scarcely longer than darning-needles.
They are in almost perpetual motion, and generally have a sort of
revolving movement, the base being the pivot.
Now, if we take a dried shell of the Sea-urchin, we shall find that the
spines will come off with a touch, and, indeed, to preserve one with all
the spines complete is a most difficult business. Let us, therefore,
pull one from its attachment, and examine its base. This will be found
to be swollen into a cup-like form, as seen in the illustration; and, if
we look at the spot whence it came, we shall see that there is a little,
rounded, polished prominence, exactly fitting into the cup, just as the
ball of the human thigh-bone fits into the acetabulum. It has also its
ligament to keep it in its place, and its same set of muscles that move
it, and is altogether a most wonderful piece of mechanism. There are in
some species of Echinus about four thousand of these spines.
* * * * *
THE legs of an insect afford excellent examples of the ball-and-socket
principle, the socket being on the body, and the ball on the base of the
leg. Some of our largest insects--such, for example, as the common
Stag-beetle--exhibit this principle very well. I have now before me a
Stag-beetle which has been dead for many years, and is quite dry and
hard. Yet I can rotate the legs almost as freely as if the beetle had
been just killed, so easily do the joints work. Even the antennæ, which
are affixed to the head by a similar joint, move about by their own
weight on merely changing the position of the insect.
These are only a few of the many natural examples of the Ball-and-socket
joint, but they are sufficient for our purpose.
THE TOGGLE OR KNEE JOINT.
Another most useful invention now comes before us, called the
Toggle-joint, or Knee-joint, the latter name being given to it on
account of its manifest resemblance to the action of the human knee.
This joint is shown in the illustration. It consists of two levers,
jointed together at one end, and having the other ends jointed to the
objects which are to be pressed asunder. It will be seen that if the
centre of the Toggle be pushed or pulled in the direction of the arrow,
so as to straighten the levers, the amount of pressure upon them is
enormous. Such an apparatus as this combines simplicity and power in a
wonderful manner, and is greatly used in machinery, especially in
presses, where the force is required to be great, but not of long
duration.
An ordinary two-foot rule, when bent, affords a good example of the
Toggle-joint, and will exert a wonderful amount of force.
[Illustration:
STRAIGHTENED
TOGGLES.
FENCERS.
BENT
TOGGLES.
PRINTING-PRESS.]
The illustration represents one of the common printing-presses that are
worked by hand. When the workman draws the handle horizontally, he
causes the two portions of the Toggle to approach a straight line. The
upper half of the Toggle being jointed to the fixed beam above, and the
other half to the movable plate or “platen” below, it is evident that
the latter will be pressed downwards with enormous force. Indeed, so
great is the power of this instrument, that a man of moderate strength
can exert a pressure of many tons.
* * * * *
WE now proceed from Art to Nature, and take first the human knee, being
the joint from which this piece of mechanism has derived one of its
names.
If the reader will look at the figure of the fencers, he will see that
the arm and leg are both Toggle-joints. In the one who is standing on
the defence they are bent, and in the other, who has just made a longe,
the Toggles of the right arm and left leg are straightened. It is by the
straightening of these joints, and not by the action of stabbing, that
the rapidity and force of a thrust are achieved.
It is just the same in boxing. No one who has the least knowledge of
sparring strikes a round-handed blow, for, putting aside the ease with
which it is parried or avoided, it has scarcely any force in it. When a
boxer hits “straight from the shoulder,” he not only straightens the
Toggle-joint of his left arm, but that of his right knee also, so that
the force of the blow comes quite as much from the leg as the arm.
It is by the right use of this joint that a small man, provided he be an
expert boxer, will easily conquer an ignorant opponent who far surpasses
him in size and weight. I have seen in a sparring-match a man not only
knocked down, but fairly lifted off his feet, by a blow from a smaller
opponent. The blow took effect under the chin, and, as the boxer hit
exactly the right moment in straightening both limbs, a very great force
was exerted with little apparent effort. I do not know which of the two
combatants was the more astonished, the one to find himself on his back
without exactly knowing how he got there, and the other to see his
antagonist prostrate without exactly knowing how the thing was done.
The jointed apparatus by which the heads of carriages are raised or
lowered is a good example of the Toggle, and exemplifies the force which
a comparatively slight piece of machinery can exercise.
* * * * *
ANOTHER form of the Toggle-joint is the process called by sailors
“bowsing” of rope. If a rope be fastened at both ends, and then pulled
in the middle, the ends are drawn forcibly towards each other. This plan
is mostly adopted in getting up sails. When a sail, say the mainsail of
a cutter, has to be hoisted as far as it will go, the last few inches
are always very obstinate. The word is then given to “bowse.” The rope,
or haulyard, is no longer pulled at the end, but a turn is taken round
the cleat, so that it does not give way. The rope is then forcibly
pulled away from the mast, when up goes the gaff a little higher. In
this way, by repeated bowsings, the gaff is coaxed, so to speak, up the
mast, and forced into its place.
Some of the leaf-rolling caterpillars act in a similar manner, by
alternately bowsing and shortening their lines. As, however, their mode
of working will be described under another heading, we will say no more
of them at present.
USEFUL ARTS.
CHAPTER II.
CRUSHING INSTRUMENTS.--THE NUT-CRACKERS, ROLLING-MILL, AND
GRINDSTONE.--PRESSURE OF ATMOSPHERE.--SEED DIBBLES AND DRILLS.
Importance of Leverage in Crushing Power.--Nut-crackers a Lever of
the Second Order.--The Chaff-cutting and Tobacconists’
Machines.--Jaws of various Animals.--The Wolf-fish or
Sea-wolf.--The Rolling-mill and its Action.--Gunpowder-mills and
Granulating Machine.--The “Jacob’s Ladder.”--The Mangle and its
various Adaptations.--The Grindstone.--Primitive Grindstones of the
Savage Races.--The Kafirs and the Inhabitants of
Palestine.--Ceasing of the Millstone.--“Facing” of
Millstones.--Tusk of the Elephant and its Structure.--Its Facings
always preserved.--Power of Self-renewal.--Pressure of
Atmosphere.--The Napier Coffee Machine.--The Cupping
Instrument.--The Pneumatic Peg.--The Magdeburg Hemispheres.--Plane
Surfaces of Glass or Metal.--Suckers of the Cuttle-fish.--Foot of
the Water-beetle.--The Limpet.--The Star-fish and its Mode of
Progression.--The Sucking-fish and the Fables connected with
it.--Its real Structure.--Modification of the Dorsal Fin.--The
Gobies and Lump-fish.--The Gecko and Tree-frog.--The Lampern and
the Medicinal Leech.--Seed Dibbles and Drills.--Labourers versus
Machinery.--Natural Dibble of the Grasshopper.--The Daddy
Long-legs.--Drills and Dibbles of the Ichneumon-flies.--A wonderful
Specimen from Bogotá.--The Pelecinus and its Mode of laying Eggs.
CRUSHING INSTRUMENTS.
As we are on the subject of leverage, we will take some examples of
levers in Art and Nature, without, however, even attempting to exhaust
the topic.
On the right hand of the illustration is shown a very familiar example
of a lever, namely, nut-crackers, with a nut between them. This useful
implement is simply an adaptation of levers of the second kind, the
power being represented by the human hand, the weight by the nut, and
the fulcrum being the joint of the instrument.
The common chaff-cutter, which is worked by hand, is another familiar
example of this kind of lever, and so is the knife used by tobacconists
in cutting cake Cavendish into threads, and by druggists for similar
purposes. In these instruments the point of the knife is jointed to some
fixed object, and becomes the fulcrum; the hand of the cutter supplies
the power, and the weight is the object which is being cut. It will be
seen that, by increasing the length of the handle, very great power can
be obtained.
[Illustration: JAWS OF WOLF-FISH.]
[Illustration: NUT-CRACKERS.]
Exchanging the power for weight, we have in the common tongs, whether
used for the coals or for sugar, a leverage of a similar character, the
weight moving over a greater space than the power. A good example of
this is to be found in the deltoid muscle of the human arm. The muscle,
which furnishes the power, contracts about an inch, and, so doing, moves
the hand over some forty inches of space. It has been well stated that
if a man is able to hold in his hand, and with extended arm, a weight of
twenty-five pounds, the muscle must be exerting a power of forty times
as great, _i.e._ about a thousand pounds.
* * * * *
THERE is little doubt that, in such Crushing Instruments as have been
mentioned, the idea has been taken from the jaws of sundry animals. We
know, for example, that with ourselves, if we desire to crack a walnut
or a filbert in our teeth, we always put it as far back as possible, so
as to make the leverage as powerful as possible. No one would ever dream
of cracking a nut with his front teeth, an act which would be very much
like that of trying to break a piece of coal by pinching it with the
tongs.
The left-hand figure of the illustration represents part of the jaws of
the Wolf-fish, or Sea-wolf, as it is sometimes called, and a very
wonderful crushing machine it is. The Sea-wolf (_Anarrhicas lupus_),
sometimes called the Sea-cat, or Swine-fish, is tolerably common on our
coasts, and, as it sometimes attains a length of seven feet, and is
proportionately stout and muscular, the power of its bite may be
estimated. The fish in question feeds chiefly on crustacea and
hard-shelled molluscs, and is therefore furnished with an apparatus
which can crush their shells. Extremes meet. The Sea-anemones, which are
mere films of animal matter, and can be torn in pieces with the finger
and thumb, can seize, swallow, and digest a crab or an oyster in spite
of the thick and strong shells in which they are enclosed. So can the
Sea-wolf, and fishes of a similar character. But nothing intermediate
can touch them, and it is curious to reflect that such opposite means
should produce a similar effect.
On reference to the illustration, the reader will see how exact is the
parallel between the Nut-crackers and the Sea-wolf’s jaws, both being
worked on the same principle, and both being furnished with a series of
projecting points, which are used for the purpose of preventing the
escape of the object which is to be crushed. The terrible grasping power
of the crocodile, the dolphin, and other predacious creatures can be
explained on the same principle.
THE ROLLING-MILL.
We now come to another variation of the Crushing Machine, _i.e._ that in
which the motion is constant, and not intermittent, as is the case with
those machines which have just been mentioned.
Perhaps some of my readers may have visited those great iron-works in
which huge masses of iron are rolled into plates of greater or less
thickness, or are cut up into strips as easily as if they were butter.
The mechanism is in its principle simple enough. The cylindrical rollers
are placed nearly in contact, and forced towards each other by
mechanical means, such as levers, screws, or springs, or all three
combined. These cylinders revolve in opposite directions, and, if any
object be placed between them, they draw it through them, and present it
on the other side in a flattened condition.
[Illustration: JAWS OF SKATE.]
[Illustration: CRUSHING-MILL AND ROLLER.]
Many years ago, one of my schoolfellows, who had been brought up
entirely under the care of some maiden ladies, was visiting a workshop,
and must needs put his finger between two revolving rollers. Of course
the hand was drawn between them, and simply squeezed flat. The machine
was instantly stopped, and the hand extricated; and the strange thing
was, that the crushed and shapeless hand afterwards recovered its full
power, though not its shape, and was able to touch the keys of the
piano.
The whole process of the Rolling-mill is singularly interesting, whether
it be used for large or small objects.
Supposing that the grooved rollers of the illustration were cut across
so as to present a number of points, it is evident that anything which
got between them would be bitten to pieces, each piece being of a
tolerably uniform shape.
This plan is now adopted in the granulation of gunpowder. After the
future powder has emerged from the hydraulic press in the form called
“press-cake,” it was formerly broken to bits with wooden or copper
mallets, and then placed in a very peculiar kind of sieve. This was
shaped like an ordinary sieve, but the bottom was made of cowhide,
pierced with innumerable holes. A round pebble was placed in the sieve,
and, when the latter was violently shaken backwards and forwards, the
powder was driven through the holes by the pressure of the stone, and
was afterwards separated into its various degrees of fineness.
I have only twice seen this process, and confess to have been in a very
nervous state on both occasions. The sieve is whirled about with
enormous velocity, and the pebble flies round as if it were a thing
alive. Let but a broken needle or a fragment of stone get into the
sieve, or even let the stone itself break asunder, and there will be an
instantaneous explosion, which will hurl the house, the machinery, and
the workmen into unknown regions.
Now, however, the mode of granulating powder is radically altered. There
is a series of double cylinders, such as shown in the illustration, and
each of them has the ridges cut into teeth in regular order. Thus the
first set of rollers or cylinders merely bites the press-cake into
convenient pieces, though seldom of the same weight.
The press-cake, thus bitten to pieces, is passed through a series of
cylindrical sieves, each graduated with the utmost accuracy, and being
turned by means of machinery. Being set on a slope, the powder runs by
its own weight down them, and all those particles which cannot pass
through the meshes are poured out untouched at the lower end.
The portions which are too large to pass the openings of the first sieve
are then handed onwards by means of a machine called a “Jacob’s Ladder,”
which consists of a series of little vessels or buckets strung on a
tape, and revolving over a couple of wheels. The first set of buckets
takes the coarsely bitten press-cake to the second set of rollers, the
teeth of which are comparatively small. Thence it is passed over to a
third set, and so forth, until it is delivered in any quality of grain
which may be required.
The modern Mangle, again, affords a good example of this principle. The
old obtrusive, costly, and cumbrous Mangle, which was nothing more than
a heavy box of stones upon rollers, has given place to the modern system
of duplex action in rollers, and one of the old Mangles is not easily to
be seen, unless it be worked as a curiosity. In fact, it is nearly as
obsolete as the spinning-wheel, which yet may be seen in some of our
country villages, where scarcely one per cent, of the population has
ever been in a town, and many of them, the women especially, make it
their boast that they have never been beyond the outskirts of their
village.
This clumsy machine is now replaced by the very simple invention which
has been in vogue for some years, and which can not only release, but
regulate, the pressure at any moment, by means of springs, levers, and
weights. This machine is, in fact, exactly the same as that which is
represented in the illustration, except that the rollers are quite
smooth. They can be adjusted to almost any amount of pressure by levers
and weights which are attached to the upper roller, and, when the linen
has passed through them, it has undergone the double operation of
wringing and mangling. This disposition of the rollers has long been
anticipated in the jaws of the Skate which crush to pieces the shells of
the whelks, periwinkles, &c., on which the creature feeds.
THE GRINDSTONE.
Being on the subject of jaws and teeth as a mode of breaking to pieces
objects which are placed between them, we will take those implements
which grind to powder, or “triturate,” instead of breaking or
flattening.
From the very earliest ages, and as soon as man had begun to discover
the “staff of life,” the art of grinding naturally assumed an
ever-increasing importance.
The first and most primitive mode of grinding corn and converting it
into meal was that which was followed by Sarah, when she welcomed her
husband’s guests, which we know, from internal evidence, was followed by
the uncivilised races who formerly inhabited this island, and by many
semi-savages of the present day.
Nothing could be simpler than the machinery used, and nothing could
cause a greater waste of muscular power. Two stones were employed, a
large one upon which the grain was placed, and a smaller which was held
in the hands, and used for grinding the corn to powder, just as the
painters of the last century used to grind their colours. The Kafirs of
Southern Africa use this simple mill, and so exactly do they keep
unconsciously to the customs of long-perished natives, that if one of
their mills were buried for a few years and dug up again, it might be
mistaken for one of the ancient “querns.” As the stone held in the hand
was rounded, it naturally wore a rounded hollow in the lower stone, and
this made the process of trituration easier. Perhaps some of my readers
may have noticed that when a chemist makes up a prescription, and is
obliged to reduce one of the ingredients to powder, he always does so by
rubbing, and not by pounding, as is generally believed. He works the
pestle round and round the mortar with a kind of twisting motion, and
thus obtains a powder much too fine to have been produced by any amount
of pounding.
[Illustration: TOOTH OF ELEPHANT.]
[Illustration: GRINDSTONE.]
The labour of this operation is necessarily very severe, and therefore
the Kafir of the present day, as did his predecessors of the long-lost
races, declines to do it himself, but hands it over to the women. In
Palestine, as in other parts of the world, a simple mill has been
invented, which takes away much of the labour, and, above all, releases
the grinder from the obligation of leaning with her fall weight upon the
upper stone. In this mill the stones are similar. The upper is moved
backwards and forwards round a pivot, and the grain is passed between
them by means of a conical aperture in the upper stone, which answers
the purpose of our “hopper.”
In order to work this mill, two women are required, sitting opposite
each other, with the mill between them, holding the same handle, and
assisting each other in turning the stone backwards and forwards. No one
who has not seen this operation can fully appreciate the force of the
saying that “two women shall be grinding at the mill; the one shall be
taken, and the other left.”
It is worthy of remark that, even at the present day, the custom of
grinding corn is carried out in Palestine as it was so many centuries
ago, and that it is repeated in Southern Africa among the Kafir tribes.
In both parts of the earth the first sound of early morning is caused by
the millstones of the grinding women, and the amount and duration of the
noise afford a sure test of prosperity. Cessation of the millstones
signifies adversity and a thin population, as has been said by a writer
who lived not very far from three thousand years ago. Speaking of
tribulation, he mentions that “the grinders cease because they be few,
and that the doors shall be shut in the streets when the sound of the
grinding is low.”
After awhile improvements were gradually introduced into the business of
grinding, not the least of which was covering its surface with ridges,
instead of leaving it entirely smooth, as it had been formerly. Millers
of the present time know the value of these ridges, and the additional
grinding power which this “facing” gives to a stone. One of these stones
is represented in the illustration, so as to show the system on which
the ridges and grooves are constructed.
* * * * *
NOW, passing from Art to Nature, we find that the whole system of the
millstone, its movement and its ridged surface, existed in the times
when man had not yet come upon earth.
The reader is probably aware that among the tooth-bearing animals there
are three types of teeth. First come the incisors, or cutting teeth,
which occupy the front of the jaw, and find their fullest development in
the rodent animals, such as the beaver, the squirrel, the rabbit, and
the rat. Next them come the canine or piercing teeth, which are so
highly developed in all the cat tribe. Lastly, there are the molar or
masticating teeth, so called from a Latin word signifying a millstone,
because their office is to grind food.
As it is with these last that we have now to treat, we will say nothing
about the others.
The molar teeth find their greatest development in the Elephant, the
structure of whose molars is exactly like that of our modern millstones.
There is certainly one very great difference. When the surface of a
millstone is rubbed away, the stone must be re-faced, and sooner or
later is worn out altogether, and must be replaced with a new one. This,
however, is not the case with the Elephant’s molar teeth, which not only
keep their facing perfectly sharp, but have the faculty of renewing
themselves as fast as they are worn away.
How these important objects are attained we shall now see.
If the reader will refer to the upper left-hand figure of the
illustration, he will see that its surface is for the most part round,
with irregularly oval figures, close and thick at one end, and almost
disappearing at the other. These are the “facings” of the Elephant’s
tooth, and they are formed as follows:--
The tooth, which is of enormous size, is not solid, but is composed of a
number of plates laid side by side, like a pack of cards when set on
their edge. Each of these plates is composed of a hard external layer of
enamel, and an internal layer of comparatively soft bony matter. A slice
of badly made toast affords a familiar parallel, the half-charred
outside representing the enamel, and the soft, sodden interior being
analogous to the bony matter. In order to show the arrangement of these
plates, a side view of part of the tooth is given on the same
illustration. Sometimes, when the teeth of fossil elephants are
discovered, these plates all fall asunder, the material which connected
them having been dissolved away in the earth.
When, however, we look upon the upper surface of a recent tooth, we see
it present the appearance which is shown in the illustration. The
elongated oval marks are the edges of the hard enamel plates, while the
spaces between them are filled with the soft bony matter. It will be
evident, then, that if two teeth such as these be in opposite jaws, and
perform the task of grinding food, their surface will always be well
“faced.” Owing to the different hardness and density of the enamel and
bony substance, the latter will wear away with comparative rapidity,
leaving the former to project slightly, and thus to preserve the facing
of the natural mill.
This is, indeed, but a modification of the beautiful animal mechanism
which keeps the teeth of a rodent animal always sharp, and always
bevelled off at the proper angle. If we could invent some plan whereby,
in our millstones, we could make the facing of much harder material
than the stone, we should make an advance in the miller’s art that would
render the millstones of the future as far superior to those of the
present as are our present millstones to the hand “quern” of the Kafir
women.
Yet another improvement has to be made. Would it be possible to
construct a millstone which should not only retain its facing, but
possess the power of renewing itself in proportion as it is worn out?
This property is found in the Elephant’s tooth, and the illustration
will give a tolerably good idea of the simple and beautiful mechanism by
which it is brought into operation.
The tooth, instead of being one solid mass, consists, as I have already
stated, of a series of plates set side by side. These plates are so
constructed that they are more worn away in front than behind. In
proportion as they are worn, a new tooth is built up behind the old one,
and gradually pushes off the old one. Now, if we could only construct
millstones with such properties, we should possess an absolutely perfect
instrument.
PRESSURE OF ATMOSPHERE.
There are many useful inventions which depend on the weight of the
atmosphere and the creation of a more or less perfect vacuum. There is,
for example, the common Pump, which raises water simply by the action of
the atmosphere. A pipe passes into the water, and in that pipe an
air-tight piston is inserted. When the piston is drawn upwards a vacuum
is formed, and the water is at once forced into it by the pressure of
the atmosphere.
Then there is the graceful and useful Napier Coffee-making Machine,
consisting of a glass globe, and vase of the same material.
Coffee and boiling water are put into the vase, and some hot water into
the globe. The two are then connected with the tube, and under the globe
is placed a spirit-lamp. Presently the water in the globe boils,
expelling the air and filling the globe with steam. The lamp is then
removed, and the steam in the globe is condensed, leaving a vacuum. The
pressure of the atmosphere then comes to bear upon the coffee in the
vase, which is forced through the tube into the globe, producing
beautifully clear and well-flavoured coffee.
* * * * *
SURGERY employs the weight of the atmosphere in the operation called
“Cupping,” now rarely employed, but formerly in such constant use that
scarcely any man who had attained middle age had not undergone it. The
operation was intended for the purpose of removing the blood from some
definite spot. Persons, for example, who appeared to have a tendency to
apoplexy were regularly cupped between the shoulders twice a year,
_i.e._ in the spring and autumn.
The mode of performing the operation is as follows:--A vase-shaped glass
vessel called a cupping-glass is placed close to the skin. The flame of
a spirit-lamp is then introduced for a moment in the glass so as to
expel the air, and the glass is rapidly placed with its mouth downwards
on the skin. If this be done with sufficient rapidity, the partial
vacuum in the cupping-glass causes it to adhere to the skin, which is
forced into it by atmospheric pressure, as shown in the illustration.
The blood is, of course, drawn towards the surface by the same means.
The glass is then quickly removed, and a little brass instrument
applied, which, at the touching of a spring, sends out a number of small
lancet-blades so formed as to make very slight cuts. The glass is again
applied, and rapidly becomes filled with blood from the cuts, the air
having forced it in exactly as it forces the coffee in Napier’s machine.
* * * * *
IN the upper right-hand corner of the illustration is shown the
Pneumatic Peg, a comparatively recent invention, and useful in cases
where much strength is not required. The base of the peg is fitted with
a sort of cup made of india-rubber. When this base is pressed against a
smooth and flat surface, such as a pane of glass, the air is forced out
of the cup, and a vacuum formed. The pressure of the atmosphere then
causes the cup to adhere to the glass with sufficient force to enable
objects to be suspended from it.
The boy’s well-known toy, the Sucker, is made on exactly the same
principle. A piece of leather, generally circular, though the shape is
not of much consequence, has a hole bored through its centre, so as to
allow a string to be attached. The leather is then soaked in water until
it is quite soft. If it be firmly pressed on any smooth object, such as
a stone, the air is forced from under it, and it becomes capable of
sustaining a weight in proportion to its dimensions. As the air has a
pressure of about fifteen pounds on every square inch, it is easy to
calculate the weight which it will uphold, a margin being left for
imperfection of vacuum.
[Illustration:
SUCKERS OF CUTTLE.
LIMPET.
STAR-FISH.
SUCKING-FISH.
FOOT OF GECKO.
LAMPERN.
CUPPING-GLASS.
PNEUMATIC PEG.
SUCKER.
MAGDEBURG HEMISPHERES.]
* * * * *
THE lower figure represents the instrument called the Magdeburg
Hemispheres, which are made for the purpose of showing the enormous
power of air-pressure. They are two hollowed hemispheres, having their
edges very accurately ground together. When used, a little lard is
rubbed on the edges in order to insure their exact fit, and they are
then pressed tightly together. The air is removed by means of the
common exhausting syringe, and it is found that the two adhere together
with such force that two strong men cannot pull them asunder. But, if
the tap be turned, and air admitted, they come apart without the least
difficulty.
Similarly, if two plates of glass or metal be ground to exactly plane
surfaces, and pressed together, they adhere nearly as strongly as if
they were one solid piece.
* * * * *
WE will now turn from Art to Nature, and examine some natural producers
of vacuum.
One of the most celebrated is that series of suckers which may be found
upon the arms of the various Cuttles. At the upper part of the
illustration a figure is given of part of an arm, on which are four
suckers. When the animal wishes to attach itself to any object, it
presses the disc of the sucker against it, and simultaneously withdraws
the centre, exactly as the boy does with his toy sucker. And, as each
arm contains a great number of suckers, it is evident that the holding
power must be very great. Indeed, on one occasion when a comparatively
small specimen had fastened on a man’s arm, he could not remove it, but
was obliged to have it cut away piecemeal by an assistant.
The common Water-beetle has similar suckers upon its first pair of feet,
and can adhere to smooth surfaces with great tenacity.
* * * * *
ON the left of the cuttle-arm is the common Limpet, shown as it appears
when adhering to the rocks. Every visitor to the seaside who has
attempted to remove the Limpets may remember how difficult it is to stir
them when they have once taken their hold. If they can be taken by
surprise, they come away with a touch; but if they become alarmed, they
press the edges of the foot firmly against the rock, withdraw the
centre, and thus create the necessary vacuum.
* * * * *
NEXT follows a Star-fish, shown as it appears when in the act of
walking, or rather, gliding along.
This movement is obtained by the use of a vast number of long suckers,
exactly resembling the pneumatic peg, except that they are flexible,
and can be curved in any direction. It is really beautiful to see the
manner in which a Star-fish will glide along by means of its suckers,
its arms accommodating themselves to the irregularities of the ground,
and its multitudinous suckers protruded and withdrawn with a
never-ceasing movement.
And, as the Star-fish is apparently blind, not having any organs which
can even be conjectured to serve the purpose of vision, this mode of
directing its course is not easily understood. Yet, blind though it may
be, it guides itself with as much accuracy as if it possessed eyes, and
evidently does so with a definite purpose, using its suckers with as
much decision as a centipede uses its legs.
These suckers can be seen very well by placing a Star-fish in a shallow
vessel of sea-water, and laying it on its back. The suckers immediately
protrude themselves from their little apertures, and the arms slowly
curve themselves so as to find something to which the suckers can
adhere. Presently one or two of the suckers will take hold of the bottom
of the vessel. Others soon follow, and in a very short time the
Star-fish is on its legs, if we may so call them, and is quietly gliding
on its way.
* * * * *
BELOW the Star-fish is seen the celebrated Sucking-fish (_Echeneis
remora_) about which so many strange tales have been told, and which is
possessed of a structure remarkable enough to need no aid from
invention. The dorsal fin of this fish is modified in a most singular
manner. The spines of which it is so largely composed are metamorphosed
into flattened plates very much resembling the laths of a Venetian
blind, and form an instrument of suction identical in principle, though
not in form, with those which have already been described. When the
sucker is pressed against a smooth surface, a vacuum is formed, and the
fish in consequence adheres firmly to the object.
The fact has been known for centuries, though it has only been lately
discovered, that the sucker was not a separate apparatus, but merely one
of the fins modified in a simple though effective manner. Indeed, any
one who has some slight notion of the structure of a fin can easily see,
by looking at the Sucking-fish from above, that the apparatus is
nothing more than the dorsal fin laid flat.
I may mention here that the name of Echeneis is taken from two words
signifying “ship-holder.” It was given to the fish on account of a
curious notion which was fully believed until quite modern times, that
the Sucking-fish had the power of attaching itself to ships, and holding
them so firmly that they could not proceed in spite of sails and oars.
The word Echeneis is used by Aristotle in his “History of Animals.” The
specific name _remora_, or “delay,” is Latin, and is given to the fish
for the same reason.
The little Gobies, which are so plentiful along our coasts, have the
ventral fins formed into a sucker, with which they can cling firmly to
any object, such as a leaf of seaweed or a smooth rock or stone. A
similar modification of the ventral fins is also found in the
beautifully coloured Lump-fish, or Lump-sucker, sometimes called the
Cock-paidle. One of these fishes, when placed in a bucket of water,
adhered so strongly to the bottom, that, when lifted by the tail, it
bore the whole weight of the pail and water.
* * * * *
JUST below the Sucking-fish is drawn a foot of the curious little
lizard, the Gecko, so called from its peculiar cry. It is common in the
West Indies, and haunts houses, traversing their walls just as flies run
up panes of glass. It is enabled to perform this movement by means of
the structure of the feet. As the reader may see by reference to the
illustration, the toes are greatly widened and flattened. If the lower
surface be examined, it will be found to be furnished with a number of
plates very much resembling those of the sucking-fish, and performing
the same office.
So rapid is the operation of these plates, that the animal can even leap
upon a perpendicular flat surface, and stick there. Perhaps the reader
may remember that the beautiful Tree-frogs, which cling so tightly to
leaves, are furnished with suckers on their toes, whereby they can hold
on even to an upright pane of glass. In fact, the smooth surface of the
glass seems to please them, and when they adhere to it they give an
excellent opportunity of examining the structure of the feet with a
magnifying-glass.
Another example of the pressure of the atmosphere has been slightly
mentioned, when treating of the ball-and-socket joint. This is the joint
by which the thigh-bone is attached to the hip. As the rounded head of
the thigh-bone fits exactly into the cavity of the hip, and is,
moreover, well lubricated with the animal oil called synovia, no air can
obtain admission between the two. Consequently, they are held together
so firmly by the pressure of the atmosphere, that they retain their
places even after the whole of the muscular attachments have been
removed. Not without very great force can the thigh-bone be dislodged
from the shallow socket in which it lies; but, if a hole be bored so as
to admit the air, it comes out at once.
Similarly, however firmly a limpet may cling to the rock, if the finest
needle were introduced so as to admit air, the creature could not retain
its hold for a moment.
* * * * *
THE last figure on the illustration represents the common Lampern
(_Lampetra fluviatilis_).
The mouth of this little fish is formed on the principle of the sucker,
and very firmly it can adhere, as I can state from much personal
experience. Indeed, it is rather alarming, to those who are unacquainted
with the character of the fish, to have it turn round and fasten upon
the hand. However, it is quite harmless, and those who are accustomed to
them will have half-a-dozen hanging on their hand at a time, and take no
notice of them.
* * * * *
ALREADY has it been mentioned that Surgery has pressed into its service
the weight of the atmosphere by means of cupping. She also makes use of
Nature in a similar manner by employing the Leech for local and surface
bleeding.
The mouth of the Medicinal Leech forms an exact parallel with the
cupping-glass and lancets, only that it is very far superior in its
powers. To make the analogy perfect, the lancets ought to be within the
cupping-glass, and the latter ought to be able to exhaust the air from
itself, and to be attached to a reservoir into which the blood could be
passed.
I need hardly mention that the action of sucking as practised by the
young of all mammalian beings, from man downwards, is due to the same
principle. By the action of sucking a partial vacuum is formed, and the
pressure of the atmosphere upon the breasts forces the milk into the
mouth of the young.
We might multiply examples _ad infinitum_, and we will therefore pass to
another subject.
SEED-DRILLS.
[Illustration:
ICHNEUMON-FLY.
GRASSHOPPER.
SEED-DRILL.]
Among the modern improvements in agriculture we may reckon the invention
of the Seed-drill as one of the most important. By means of this
invention, seed is greatly economized, the supply can be regulated, and
the sower knows exactly where every grain of seed goes. There is no
scattering, as in the wasteful broadcast plan, by which the seeds are
flung almost at random over the field, and may or may not fall into the
furrows. The Seed-drill, on the contrary, either stamps holes or ploughs
narrow furrows, measures the seed into them, and in some machines
replaces the earth. The former kind of machine rather deserves the name
of a dibble, and was invented for the purpose of superseding the use of
the hand-dibble.
It is really a pitiful thing to see human beings endowed with reason and
aspirations performing such a task as dibbling by hand, one going
backwards with a dibble in each hand, and the other following and
putting seed into the holes. Yet the field labourers have the greatest
objection to the machine dibble, as, indeed, they have to any sort of
labour-saving machine, thinking that it will lessen the demand for
labour, and prevent them from earning a livelihood.
I well remember how a country clergyman, pitying the hard toil of the
hand-dibblers, took occasion when he visited town to purchase a machine
dibble wherewith one man could set eight rows of beans at once. It was a
very simple affair, comprehensible even by the dull brain of a Wiltshire
labourer. His trouble was all in vain, for no one would use it, and
there was such a disturbance about it in the village, that for the sake
of peace its owner laid it up in a loft and abandoned its use. There
might be some semblance of reason in thinking that it would deprive them
of their field labour, but no cottager would even use it in his own
garden, though it was freely offered to any one who wished to borrow it.
* * * * *
THESE machines have their parallels in Nature, two of which are
represented in the illustration.
The lower left-hand figure represents the female Grasshopper depositing
her eggs. She is furnished with a sharply pointed ovipositor, composed
of two blades. When she is about to lay her eggs, she searches for a
suitable piece of ground, where the earth is tolerably soft, and with
the closed ovipositor bores a hole. She then separates the blades
slightly, and an egg glides between them into the ground, precisely as
is done by the machine dibble with its beans. When I first saw and used
the instrument, some twenty-five years ago, the parallel struck me at
once.
* * * * *
THE female of the familiar Daddy Long-legs (_Tipula_) acts in a similar
manner. She is furnished with an ovipositor too short to be used like
that of the grasshopper, and so she attains her object in a rather
different manner. Making use of her long stilt-like legs, she sets
herself nearly upright, with the point of the ovipositor in the ground.
She then twists herself from side to side, just after the principle of
the bradawl, and so proceeds until she has made a hole large enough for
her purpose. The blades of the ovipositor are then separated, and the
egg placed in the hole, as has been described of the grasshopper.
* * * * *
THE upper figure represents one of the large Ichneumon-flies depositing
the egg in the grub of some wood-inhabiting larva. How she bores the
hole has already been described when treating of Boring Tools, and the
process need not again be discussed. The principal point at present is,
that after the hole is bored, an egg can pass between the blades of the
ovipositor, though they are but little thicker than human hairs.
One of the most extraordinary instances of this kind of ovipositor is
found in an Ichneumon-fly brought from Bogotá. The body, from the head
to the end of the tail, is not quite an inch long, while the ovipositor
is six inches and a half in length, and scarcely thicker than that of
the insect whose portrait is given in the illustration. Nothing is as
yet known of its habits, so that the object of this wonderfully long
ovipositor is a mystery. But that it should be used like other
ovipositors is evident enough, and the chief wonder is, what are the
mechanical means whereby an egg can be propelled between blades so long
and slender.
There is a genus of Ichneumon-flies called Pelecinus. They deposit their
eggs in wood-boring larvæ, and we might imagine that the ovipositor
would be a long one. It is, however, extremely short, and the requisite
length is obtained by the form of the abdomen, the joints of which are
so long and narrow that they almost look as if they had passed through a
wire-drawing machine, the length of the head and throat being
three-eighths of an inch, and that of the abdomen an inch and a half.
This long abdomen belongs only to the female, that of the male being
short and club-shaped.
USEFUL ARTS.
CHAPTER III.
CLOTH-DRESSING.--BRUSHES AND COMBS.--BUTTONS, HOOKS AND EYES, AND CLASP.
The Teazle and its Structure.--Its Use in raising the “Nap” on
Cloth.--Its Value in Commerce.--Artificial Teazles.--The modern
Cloth-dressing Machine.--The Brush an Article of
Luxury.--Definition of the Brush, and its various Uses.--Brushes in
Nature.--The Foot of the Fly and the Tail-brush of the Glow-worm
Larva.--Mode in which they are used.--The Comb.--Varieties of the
Comb as made in different Countries.--Combs in Nature.--Foot of the
Spider and its Uses.--Beak of the Toucan.--Comb of the
Scorpion.--Buttons, Hooks and Eyes.--Use of the Button.--The
Egyptian Garment.--The Buckle and the Shoe-tie.--The
Clasp.--Wing-hooks of various Insects.--The Saddle-back Oyster.
CLOTH-DRESSING MACHINE.
In former days, when so much was done by hand that is now done by
machinery, the thistle called the Teazle (_Dipsacus fullonum_) was of
great value in British commerce, being used by countless thousands in
the manufacture of broadcloth.
When the woollen threads are woven so as to form the fabric of the
cloth, there is no nap upon them, this having to be produced by a
subsequent process. The plan of former days was, to procure a quantity
of the seed-vessels of the Teazle, and dry them. They were then fastened
to an instrument something like a wooden battledore, and swept over the
surface of the cloth. By degrees the delicate hooklets which terminate
the many scales of the seed-vessel tore up the fibres of the cloth, and
produced the desired nap without impairing the strength of the thread.
When this nap is worn off, the threads are again visible, producing the
effect called “threadbare.”
As the art of weaving continued to progress, the demand for Teazles
increased in due proportion, and vast quantities were imported from
abroad. Instead of being used by band, they were then fastened to the
circumference of wooden wheels as broad as the width of the cloth, and
made to revolve rapidly, while the cloth was pressed against them.
[Illustration: TEAZLE.]
[Illustration: CLOTH-DRESSING.]
For many years attempts had been made to construct artificial Teazles
which would not wear out so rapidly as did the dry seed-vessels, but
nothing could be constructed that was not too stiff or too strong, and
which did not injure the threads while producing the nap. At last,
however, this difficult problem has been solved, and the Teazle is no
longer an important article of commerce, its place being supplied by
delicately made cards of the finest and most elastic wire.
In the illustration a head of Teazle is given on the left hand, and on
the right is seen the mode in which the wire cards are placed in the
machine, and the cloth drawn over them so as to produce the required
nap.
BRUSHES.
It is worthy of notice that there are many articles of comparative
luxury which could not be used until man had attained some degree of
civilisation. Among these we may class the Brush and the Comb, no true
savage ever troubling himself about either article. The Brush, indeed,
belongs to a much more advanced stage of civilisation than the Comb, for
whereas we find combs, however rude they may be, used in semi-savage, or
rather, barbarian countries, the Brush is, as far as I know, an adjunct
of a high state of civilisation.
Brushes may be defined to be instruments formed of fibres set more or
less parallel to each other. The vast variety of brushes used in
different parts of Europe is indicative of the civilisation of the
nations who use them. Take, for example, the brushes used in household
management, such as the hearth-brush, the housemaid’s brush, the
Turk’s-head brush, the crumb-brush, the stair-brush, the carpet-brush,
the dusting brush, and many others.
Then we have those which are applied to our garments, such as the
ordinary clothes-brush, the velvet-backed hat-brush, and the three kinds
of boot-brushes.
In architecture, again, we should be very badly off without the
painting-brushes, the whitewasher’s brush, and the paper-hanger’s brush;
not to mention the exceeding variety of brushes used by artists both in
oil and water colours.
As to brushes applied to our persons, we have an infinite number of
them. There is, of course, the hair-brush, without a pair of which, one
for each hand, no one with a respectable head of hair could be expected
to be happy.
We may add to this the revolving brush worked by machinery, which is to
be found in the rooms of any respectable hairdresser, and which is a
sort of an apotheosis of the Hair-brush, especially when it is worked,
as in some places, by the electrical engine.
Then there is the shaving-brush, once an absolutely necessary article in
a gentleman’s dressing-case, and above all requisite if the owner should
happen to be a clergyman. Nowadays, shaving is rapidly decreasing, and
of all the professions, those who are most largely bearded, both in
number of beard-wearers and dimensions of the beard, are to be found
among the clergy.
Then there are any number of tooth-brushes for the interior of the
mouth, and of flesh-brushes, with or without handles, for the service of
the bath. There are even gardeners’ brushes, for the purpose of clearing
the plants of the aphides, or green-blight, as these insects are
popularly called by gardeners. So it will be seen that--absurd as the
proposition may appear at first sight--we may really accept the use of
the brush as a safe test of the progress of civilisation.
* * * * *
WE will now glance at the illustrations of this subject.
On the right hand is depicted the once honoured Shaving-brush, the
terror of all stiff-bearded men on frosty mornings, and yet clung to
with a strange inconsistency. Many years ago a military member of the
House of Commons was sensible enough to wear his beard, and was, in
consequence, the butt for interminable jokes. At the present time, if
the House were counted, a great majority of the younger, and not a few
of the older, members will be found to wear either the beard or
moustache, or both.
[Illustration: FOOT OF FLY.]
[Illustration: BRUSH OF GLOW-WORM LARVA.]
[Illustration: HAIR-BRUSHES.]
[Illustration: SHAVING-BRUSH.]
Perhaps some of my readers may object that many nations in a state of
very partial civilisation are accustomed to shaving. So they are, but
they do not use the shaving-brush. Most of them content themselves with
pulling out the hairs by the roots, while others merely saturate the
hair with hot water, and so need no brush.
Next to the shaving-brush is drawn a pair of ordinary Hair-brushes, such
as have been mentioned.
* * * * *
PASSING to the left, we find an object which bears a curious resemblance
to the shaving-brush. This is an apparatus belonging to the larva or
grub of the Glow-worm. This creature feeds upon snails, and, in
consequence, gets itself covered with the tenacious slime. In order to
enable it to rid itself of this inconvenience, the larva is furnished
near the end of its tail with the curious apparatus which is here shown.
It consists of some seven or eight soft white radii, arranged so as to
produce a brush-like outline, and being capable of extension or
withdrawal at will.
It had long been known that this “houppe nerveuse,” as it is called, was
employed as an assistant in locomotion; but until comparatively late
years--I believe about 1826--no one seemed to be aware that it was used
as a brush. Its functions as a brush may be compared with the somewhat
similar offices fulfilled by the pincers of the Earwig, as mentioned on
page 259.
Next to the brush of the glow-worm larva is shown one of the fore-feet
of the ordinary house-fly, much magnified. Passing, as irrelevant to the
present subject, the use of the feet as organs of locomotion, we may
take them as being used for the purpose of cleansing the body of the
insect.
I suppose that none of my readers has been sufficiently inobservant not
to have noticed the way in which a fly cleanses itself, behaving almost
exactly like a cat under similar circumstances. The fore-feet are
repeatedly passed over the head, which is bowed down to meet them, while
a similar office is performed for the rest of the body by the hind-legs.
The feet are then rubbed against each other, so as to free them from all
accumulations, just as the housemaid cleanses the hair-brush with the
comb before washing it. So mechanical is this process, that a fly has
been known to go through it even after it had been deprived of its head.
The reader will see, on reference to the illustration, that the two
sharp and curved claws are capable of answering the purpose of combs,
and, indeed, are so employed.
COMBS.
We will now proceed to the COMB, and see how Art has been anticipated by
Nature.
As long as human beings possess hair upon their heads, whether it be the
short, frizzed, woolly pile of the negro, the thick, coarse crop of the
Fijian, the coarse, straight hair of the Mongolian, or the long and fine
hair of the Georgian races, they must, as soon as they attempt any kind
of civilisation, form some instruments by which the hair can be dressed.
The simplest machine for this purpose is the Comb, and I possess many
varieties of this article, suitable to the different races for whom it
was made.
Putting aside the ordinary Combs of our European civilisation, such as
are given in the illustration, there are many others which are modified
according to the use which they have to fulfil.
[Illustration:
FOOT OF SPIDER.
BEAK OF TOUCAN.
COMBS.]
The simplest is the Comb of the celebrated Amazon regiment of Dahomey.
This is nothing but a slight skewer of ivory, some ten inches in length,
and amply sufficient for arranging the short woolly lumps which do duty
for hair on the head of a true negro. One of these very primitive combs
is in my collection, together with an undress costume of the Amazon in
question, and both being very much suited to each other. The comb being
a simple skewer, the dress is only a few thongs of leather, but they are
both equal to the requirements of their wearers.
As much time would be lost in combing the hair with a single skewer,
especially when that hair belonged to any but the pure negro races, a
simple but obvious improvement was introduced. A number of skewers were
lashed together side by side, with their ends a little diverging, and
thus was formed the germ of our present Combs.
As to the varieties of the Comb, they are simply endless; and whether
they are intended, in the form of the Currycomb, to smooth the harsh
coat of a horse, or, as a small-tooth Comb, to search the hair of the
young, they are all based on one principle.
It is really curious to see how often two men, who cannot possibly have
seen each other, will hit upon the same idea, not only simultaneously,
but often in the very same words. So it is with regard to the Comb. In
no two parts of the world can the natives be more opposed to each other
than is the case with Fiji and Western Africa; yet I possess specimens
of combs from both countries, made on the same principles, and so
exactly in the same manner, that, except for the coarseness of the
African Comb, it would be almost impossible to distinguish between them.
There is but a slight difference in the size and shape of the two combs,
and yet nothing can be more distinct than the characters of the two
nations.
I have also a Japanese Comb of the most ingenious construction. It is
made of wood, and cut exactly like our double ivory small-tooth comb;
but it is furnished with a curious kind of handle, consisting of a flat
piece of wood with a deep longitudinal slit, into which either side of
the comb fits; and so beautifully is it made, that when it is fitted
upon either side of the comb it looks as if handle and comb had been cut
out of the same piece of wood.
The Fijian Combs are much after the same fashion as those of Western
Africa, except that, with the artistic nature of their kind, the
Fijians, instead of merely lashing together the numerous spikes of which
the comb is made, employ a variety of patterns, and seem to luxuriate in
the exuberance of artistic spirit which can make hundreds of combs, and
no two of them alike.
* * * * *
ON the left hand of the illustration are two examples of Natural Combs
which are well worthy of notice. The upper one is a foot of the common
Garden Spider (_Epeira diadema_), which has been several times mentioned
in this work in connection with different subjects.
Every one who has watched the life of one of these creatures must have
noticed how often its hairy body becomes clogged with little bits of its
own web, and how dexterously it releases itself from such encumbrances.
The figure in the illustration shows how this can be done, the strangely
formed foot acting at the same time the part of comb and brush. It will
be seen that the curved spikes of the claws act as a comb, while the
bristle-like hairs discharge the duty of a brush.
* * * * *
NOT only are these projections used as Combs, but as appendages which
insure the security of footing along the lines of the web. The reader
will easily remember that when a Spider rushes along its web to secure
its prey, it always runs along one of the radiating lines, which have no
viscid drops, and that it never misses its hold. The latter point is
secured by the structure of its claws, which are so made that if one
projection misses the line, another is sure to fasten upon it. Some
years ago, while watching “Blondin” go through his wonderful
performances, I was especially struck with the pattern on which he had
constructed the stilts upon which he traversed the rope. They were made
in the most exact imitation of the Spider’s foot, and though it is not
probable that he borrowed them from that object, the resemblance was so
close that he might readily have done so.
* * * * *
BELOW the spider’s foot is given the head of a Toucan, one of those
beautifully coloured and large-billed birds that inhabit tropical
America. These birds are very particular about their plumage, and even
when in captivity dress their feathers with the utmost care. When they
do so, the saw-like notches of the beak act the part of a comb, and the
fibrils of the feathers are by their action dressed parallel to each
other, and give to the whole bird its proper appearance of health.
* * * * *
I MAY here mention that there is one comb in Nature, the use of which
has never been clearly ascertained. This is the remarkable organ found
in the Scorpion, and simply known as the “comb.” There are two of them,
one on each side of the under surface. Their colour differs slightly
according to the species, but is generally a light yellow brown. The
number of teeth also differs extremely, for in the Rock Scorpion there
are only thirteen teeth, while in the Red Scorpion there are
twenty-eight.
BUTTONS, HOOKS AND EYES, AND CLASP.
HAVING now treated of brushes and combs as articles belonging to the
toilet, we will proceed to those which belong to the dress rather than
the person. It is a curious fact that, as far as is known, buttons and
hooks belong only to advanced civilisation. The simplest garment is, of
course, a cloth of some material wrapped round the waist, and, as we see
in the wonderful Egyptian paintings which have survived their painters
some three thousand years, the simple fold can retain its grasp round
the loins, even through the exertions of a long day’s work.
I was always at a loss, when looking at these drawings, to understand
how a single fold could retain so simple a garment in its place, but
when I made my first visit to the Hammam Turkish Bath in Jermyn Street
the mystery was at once solved. The “check,” as it is there called, is
long enough to pass about once and a half round the waist of an ordinary
man. One end of it is placed on the left side, so as to bring the lower
edge on a level with the knee. It is held by the left hand until the
right hand passes it round the waist. It is then turned over in a broad
single fold, and will remain in position for hours, the left leg having
free scope between the two ends, and yet not being needlessly exposed.
Next to the simple fold comes the tie, which is in use all over the
world. The chief object of a good Tie is that it should retain its hold
as long as needed, be loosened with a touch in necessity, and, as a
matter of consequence, should never “jam.”
Still, even the best of ties are liable to objection. I once heard an
argument on the subject of ties and buckles with regard to shoes. The
speakers were both Derbyshire men, and their phraseology was somewhat
obscure. However, both stuck to his own principles, one saying that
“when a shee-uew is boo-oo-oockled, it’s boo-oo-ookled;” and the other
asserting, in equally strong terms, that “when it’s tee-ee-eed, it’s
tee-ee-eed.”
The buckle was here asserting its supremacy in civilisation over the
tie, and was palpably right. Any one, so rose the argument, can tie two
strings together, but the structure of the buckle is too complicated to
be understood, much less invented, by any uncivilised being.
* * * * *
NEXT come, in natural order, the Button and the Clasp, each being
identical in principle. In the case of the former the “eye” is placed
over the button, while in the latter the clasp or hook is passed through
the eye. Several examples of the Button and the Clasp are given on the
right hand of the illustration, and are too familiar to need
description.
* * * * *
AS to the corresponding articles in Nature, they are very numerous. We
will take, for example, the Saddle-back or Crow Oyster of our own
shores. It is a most remarkable being. It deposits upon the object to
which it adheres a sort of button of shelly matter, and the lower valve,
which is nearly flat, has in it an aperture which is placed over the
knob, just as a button-hole goes over the button. As this arrangement is
confined to the lower valve, and cannot be seen unless the upper valve
be removed, the lower valve only is shown in the illustration, as it
appears when fastened to the side of a large limpet.
[Illustration: WING-HOOKS OF INSECT. SADDLE-BACK OYSTER.]
[Illustration: CLASPS AND BUTTON.]
* * * * *
OF the Hooks and Eyes in Nature I have only taken two examples, though
there are many others.
We all know the Bees, Wasps, Hornets, and other similar insects, and
that they possess four wings. I may here mention that no insect which
does not possess four transparent wings is capable of stinging.
When the insect is at rest the four wings may be easily distinguished,
but when it is in flight they coalesce, so that practically the insect
has two wings instead of four. This object is attained in the following
way:--
The lower edge of the first pair of wings is turned over in a rather
stiff fold. The upper edge of the second pair of wings has a row of
small, but strong and elastic hooks. When the insect is about to fly,
the hooks are hitched into the fold, and so the wings are fastened
together. These hooks are shown in the illustration, and the reader will
easily see how effective they must be in their operation. An almost
exactly similar structure is found in the feathers of birds, and it is
by means of these tiny hooks that wings are enabled to present a
continuous, light, and elastic surface in the air.
USEFUL ARTS.
CHAPTER IV.
THE STOPPER, OR CORK.--THE FILTER.
Vessels and their Covers.--Corks.--Mode of bottling Wine.--Conical
Corks and Stoppers.--Self-fitting Candles.--Candle-fixers.--The
Vent-peg.--The Blow-guns and their Missiles.--The Serpula and its
Conical Stopper.--The Filter.--The Bosjesman procuring Water.--How
to make a simple Filter.--The Earth as a Filter.--The Sea-mouse, or
Aphrodite, and its filtering Apparatus.--The Duck’s Beak, and its
beautiful Structure.--The Jaw of the Greenland
Whale.--Fork-grinder’s Respirator.--How Insects
breathe.--Spiracles, and their general Structure.--Spiracle of the
Fly.--Experiment upon a Cockroach, and its Result.
THE STOPPER, OR CORK.
This object, as depicted in the illustration, is a product of civilised
life, though, as soon as a savage could make a vessel, he seems to have
made a Cover for it if it were of large diameter, or a Stopper if the
opening were small. Even the very Bosjesman, who is quite unable to make
a clay vessel, and uses empty ostrich eggs by way of water-bottles, is
yet capable of making plugs with which he can stop up the apertures.
Then the Kafir, with his gourd vessels, whether they be for water or
snuff, makes a plug that fits tightly enough to exclude the air, as well
as to retain the contents.
The invention of glass bottles necessarily brought with it the
introduction of a new kind of plug, and a material for such a plug was
found in the bark of the cork-tree, a species of oak. This bark
possesses the capability of compression to a very great extent, and,
being highly elastic, it expands as soon as the pressure is removed.
Thus, in bottling wine, the corks are always made much too large to go
into the mouths of the bottles. They are first dipped in a cup
containing the same wine, and are then compressed violently by a machine
worked by a handle, and which, being practically a powerful pair of
nut-crackers with a rounded gripe, must suit the shape of the cork. It
is then taken out of the machine, and, before it has had time to expand,
is rapidly fitted to the neck of the bottle, and driven home with a
wooden mallet. Expansion then takes place, and the bottle is rendered
air-tight, so that no damage is done to the wine.
If the whole of the wine were to be drunk when the cork was removed,
this plan would be amply sufficient. But there are many cases where the
bottle is opened, and only part of the wine consumed. To re-cork the
bottle would be too troublesome, and to leave it uncorked would spoil
the wine. So the Conical Stopper was invented, which fits the neck of
any ordinary wine-bottle, according to the depth to which it is
introduced, and, by a slight screwing movement, sufficient compression
is obtained to render the bottle air-tight. One of these Conical
Stoppers is shown in the illustration on page 352. Sometimes they are
made of cork, and sometimes of india-rubber; but the principle is the
same in either case.
Perhaps some of my readers may have seen the Self-fitting Candles, which
require no paper to make them fit the candlestick. These are enlarged at
the base, which is made in a conical form, and slightly grooved. The
“Candle-fixers” that are so much in use at the present day are made
exactly on the same principle, being hollow cones of paper, which take
the place of the solid cone.
The Vent-peg of casks is another instance of the cone used as a stopper.
Another example is to be found in the Blow-guns and Arrows of tropical
America. In some districts the base of the arrow is fitted with a
conical appendage of light cotton, rather larger than the tube, but
capable of compression, so that it exactly fits the tube when pressed
into it. In other districts the cone is hollow, and made of some thin
and elastic bark.
Some years ago one of our most eminent gun-makers hit upon the same idea
while making improved missiles for the game of “Puff and Dart,” and very
much surprised he was when I showed him the South American arrow, not
only with the same hollow cone at the base, but having also spiral
wings along the shaft, so as to give it a rotatory motion as it passed
through the air. The hollow cones of his darts were made of
india-rubber, but the shape of the two was identical.
* * * * *
IF the reader will refer to the left-hand figure of the illustration, he
will see a beautiful example of the Conical Stopper as existing in
Nature.
This is the “Stopper,” as it is popularly called, and, scientifically,
the “infundibuliform operculum.” I prefer the former term myself, as
being less liable to misapprehension.
The Serpula lives in a shelly tube of its own construction, and has the
power of protruding itself when it desires to obtain food, and of
withdrawing itself within the tube when alarmed. This movement is
performed so rapidly, that the eye can scarcely follow it, and the
mechanism by which it is done has already been described when treating
of War and Hunting.
[Illustration: ANTENNA OF SERPULA.]
[Illustration: CONICAL STOPPER.]
When it withdraws itself, the Stopper closes the mouth of the tube with
perfect exactness, so as to leave the inhabitant in safety. The reader
will see, on referring to the illustration, how exactly similar is the
Conical Stopper of Art to that of Nature, and how the inventor of that
article, as well as of the self-fitting candle, the candle-fixer, the
blow-gun arrow, and the vent-peg, might have found prototypes of their
inventions in Nature, if they had only known where to look for them.
THE FILTER.
Even in a state of uncivilisation man has been driven to invent a Filter
of some kind.
The simplest kind of Filter is that which is used by the Bosjesman
women when procuring water for the use of their families. When, as often
happens, the only water to be obtained is to be found in muddy pools
which have been trampled and perturbed by thirsty animals, the women
have recourse to a simple, though rather repulsive, expedient.
Each woman is furnished with empty ostrich egg-shells by way of
water-vessels, and she also takes a couple of hollow reeds. Over the end
of one of these reeds she ties a bundle of grass, and then plunges it as
deeply as she can into the mud. After a little while she sucks up the
water through the tube, the grass acting as a filter, and she then
discharges it by the second tube into the egg-shells. In this way the
women will obtain water, where none but themselves could have procured
it. As to the repulsive mode of obtaining it, no one can be fastidious
when dying of thirst. Sir S. Baker mentions that when he was on his
travels he managed in a halt to save up enough water for a bath for
himself and his wife. He was about to throw away the soapy water, when
the vessel was snatched from his hands by two of his attendants, and the
contents eagerly drunk.
The different varieties of the Filter which we use at the present day
are too familiar to need description. Whether they be made principally
of charcoal, which is a powerful disinfectant, or of merely stones,
gravel, and sand, they are all constructed on the same principle,
namely, the straining out solid substances, and allowing only the pure
water to pass through the interstices.
* * * * *
AS to the Filters of Nature, they are almost innumerable. In the first
place, the Earth itself is the primary filter of all, taking into itself
all kinds of decomposing substances, separating them for the use of
vegetation, and delivering the pure, bright, and sparkling spring water
which we so highly and rightly value. The whole human body, again, is
practically a collection of the most elaborate and effective filters
that the mind of man can conceive. But we will pass to the more obvious
examples of filters as seen in animal life.
On the upper left-hand portion of the illustration may be seen a long,
fat, hairy creature, called popularly the Sea-mouse, and known to
zoologists as _Aphrodite aculeata_. Although it inhabits the mud--and
sea-mud is about as noisome a substance as can be imagined--it is
clothed with a garment of such beauty that the rainbow itself can
scarcely rival, and not surpass it. The hairs with which it is so
profusely covered glitter and sparkle with every imaginable hue, among
which red and green seem to be predominant.
These hairs occupy the sides of the body, but in the upper surface there
is a thick coating of felted hairs, interwoven with each other so
closely that they can with difficulty be separated. These hairs form a
natural filter, strain away the mud from the water, and allow the latter
to pour itself upon the organs of respiration. If, therefore, a specimen
be examined when it is first brought up by the dredge, the felted hair
will always be found to contain a considerable amount of mud, and much
washing is needed before the creature can be introduced into an aquarium
where the water is intended to be transparent.
[Illustration: APHRODITE. DUCK’S BEAK.]
[Illustration: FILTER.]
I may here mention that the name of Aphrodite is a singularly happy one.
It signifies something that arises from the foam of the sea, and was
given to the goddess of beauty, because in the ancient myths she was
said to have sprung from the foam of the sea. Unpoetical as it may
appear, the German word Meerschaum, which is so familiar to us in
connection with pipes, is the exact equivalent of Aphrodite.
* * * * *
BELOW the Aphrodite is a figure representing the filtering apparatus
which is found in the beak of the duck. This singularly beautiful
apparatus is well worthy of examination, and the more important details
of its structure can easily be made out by the unassisted eye.
In the first place, the upper half of the beak, or upper mandible, as
it is scientifically called, is furnished along its edges with a row of
curved horny projections, very like the teeth of a comb, and each of
them coming to a point. There are some fifty or sixty of these teeth on
each side, and they are regularly graduated in size, being longest in
the middle of the beak, and becoming very short at either end. They are
set diagonally, with the tips pointing backwards. The edges of the lower
mandible are turned up in a sort of fold, on the outside of which is a
row of grooves corresponding with the teeth of the upper mandible, and,
like them, being set diagonally.
These teeth and grooves would of themselves make a very efficient
filter, but they are further aided by the tongue. This is thick, fleshy,
and very mobile; so much so, indeed, that when the mouth is opened the
tongue is automatically thrust forward. The edges of the tongue are,
like those of the mandibles, furnished with a filtering apparatus.
Instead, however, of being horny and stiff like those of the mandibles,
they are membranous and exceedingly delicate. Indeed, in order to see
them properly, it is necessary to place the tongue under water, so that
the membranous filaments shall be floated apart instead of clinging
together by their own weight.
The whole of this apparatus is abundantly supplied with nerves, and is
evidently a most exquisite instrument of touch. The reader will now
understand the peculiar movements of a duck’s beak while feeding.
Although the bird can and does eat solid food, such as barley, and, by
reason of its superior width of beak, will very much defraud the poultry
in a yard where ducks and hens are kept together, it is chiefly fitted
for extracting nourishment from water, and will find abundant
subsistence where a hen would die of starvation.
When the beak is plunged into the water, the mandibles are rapidly
opened and shut, the tongue incessantly working backwards and forwards
between them. Consequently, not only are the solid parts of the water
strained between the comb of the upper beak and the grooves of the
lower, but they undergo a further sifting or filtering from the delicate
fibrils which fringe the edge of the tongue.
* * * * *
ANOTHER familiar example of the Filter is to be found in the jaw of the
Greenland Whale. In this animal, as well as in its congeners, the
“whalebone,” or “baleen,” as it is more properly called, is so formed
that it allows liquids to pass through it, while it retains solids.
Feeding as it does upon small marine matters, it would starve but for
the filtering power of the baleen, which enables the animal to take into
its vast mouth the sea-water with its inhabitants, and to expel the
water through the plates and fibres of the baleen, while retaining the
animals.
The process of filtering, as well as the structure of the baleen, is so
familiar that it does not need further description.
* * * * *
WE will now proceed to another filter, which is used in the air, and not
in water, namely, the Mouth-guard or Respirator of the fork-grinder.
There is, perhaps, no trade which is more destructive of human life than
that of the fork-grinder was until the peculiar respirator was made
obligatory. The minute particles of steel thrown off by the grindstone
fill the air, and were necessarily inhaled. Now, the human lungs are
capable of enduring very bad treatment, but the introduction of
steel-dust into them is more than they can bear. Consequently the
duration of human life was very short, consumption almost invariably
setting in at an early age, and carrying off the men before they had
achieved middle age.
Nor did the mischief end there. It was bad enough that life should be
shortened, but far worse that it should be wasted, as was mostly the
case. The men, knowing what their fate must be, were simply reckless,
and plunged into all kinds of debauchery, under the plea of “a short
life and a merry one.” They knew no better, and could scarcely be blamed
for their mode of living. And, as a matter of course, each succeeding
generation was worse, smaller, and feebler than the preceding.
Then there came the invention of the Magnetic Respirator, by which the
fork-grinder’s trade was rendered as healthy as any other. It was made
of steel-wire gauze, and magnetised, so that the floating particles of
steel were not only stopped in their progress to the lungs, but arrested
by the magnetism, and, so to speak, taken prisoners by it.
Even a well-made respirator of several layers, like those which are used
by persons suffering from weak lungs, would have been useful, but the
addition of magnetism doubled the efficacy while greatly diminishing the
cost, a single layer of wire being quite adequate to the office, and
was, in fact, quite a stroke of genius.
The value of this invention is at once shown by the many complaints
which the workmen made when the Respirator was first introduced. They
complained that the apertures of the Respirator became so choked that
they could not breathe. This was perfectly true, but the complaint
showed the real value of the instrument.
[Illustration: SPIRACLE OF FLY.]
[Illustration: RESPIRATOR OF FORK-GRINDER.]
It was necessary for the workmen, every now and then, to clear off the
innumerable particles of steel which adhered to the magnetised wires,
and impeded respiration. But they never seemed to realise the fact that,
if it had not been for these wires, all the particles would have been
drawn into the lungs, and gradually choked them up, brought on
inflammation, and extinguished their life altogether. And, with the
usual repugnance to new ideas which is inherent in undeveloped minds,
the men stoutly resisted the introduction of the Respirator, and did
their best to reject an invention which doubled the length of their
lives, and enabled them to find long happiness in the world instead of
brief pleasure ended by sure and painful death.
* * * * *
NOW, we will see how the principle of the Respirator is carried out in
Nature.
On the left hand of the illustration is drawn one of the most perfect
Respirators, or air-filters, if we may use the term, that can be
imagined. Perhaps some of my readers may know that insects do not
breathe as we do. They have no lungs, but their entire system is
permeated by air-vessels, just as is our system with blood-vessels, and
therefore the air, instead of being restricted to the lungs, is conveyed
to every part of the insect, the air-vessels extending to the very tips
of the wings and antennæ, and to the claws of the feet.
Neither does the insect receive the air through mouth or nostrils as we
do. Along the sides of the body are certain oval apertures called
“spiracles,” from the Latin word _spiro_, which signifies breathing.
These spiracles can easily be seen by examining an ordinary silkworm.
They are situated in the soft and flexible skin which connects the rings
or segments of which all insects are composed, and pass directly into
two large air-tubes which run on either side of the body.
It is evident that since an insect is so thoroughly permeated with air,
it must be furnished with means to render that air as pure as possible,
and at all events to preserve the respiratory system from being choked
with dust or other adventitious substances.
How important the air is to an insect can easily be seen by dipping it
in oil, or even brushing an oiled feather on its sides so as to fill up
the spiracles. A man under the hands of the hangman or garotter could
not die more swiftly, so much does an insect depend on air. In fact, an
insect is almost wholly composed of air-tubes, but for which the great
thick-bodied dor-beetles could never use their organs of flight.
Of course, although the spiracles can act as filters as far as the air
is concerned, they cannot be analysts, and consequently insects are
peculiarly sensitive to a bad atmosphere. There is, for example, the
well-known “laurel-bottle” of entomologists. A few young laurel-leaves
are crushed and placed in a bottle. As soon as an insect is introduced,
it breathes the prussic acid which is exhaled from the leaves, and at
once dies.
So it is with the more delicate “death-bottle,” into which a little
cyanide of potassium is introduced, and covered with plaster of Paris.
The plaster prevents the poison from touching the insects and damaging
their beautiful colours. It permits the deadly vapour to roll through
its interstices; consequently, even the large-bodied moths, which are
tenacious of life almost beyond credibility, can barely run round the
bottle, when they roll over, and expire almost without a struggle, the
venomous atmosphere having saturated the entire body.
All entomologists know that the spiracles act as sieves, preventing any
extraneous objects from gaining admission into the breathing-tubes. But,
unless they have had personal experience, they cannot appreciate the
efficacy of the spiracle when acting as a respirator. Even the
microscope, though it may magnify the object to any extent, does not
show the wonderful filtering power of the spiracle. The figure in the
illustration represents a spiracle of the common “blue-bottle” fly, and
any one who wishes to examine such an object for himself can have but
little difficulty in doing so, especially in the warm season of the
year.
How effectual is the barrier thus interposed by Nature between the
external world and the interior of the insect may be inferred from the
following narrative:--
Many years ago, while absorbed in the comparative anatomy of insect
structure, I believed myself to have hit upon a plan for injecting the
minutest of tubes with mercury. So I took a male cockroach, placed a
vessel of mercury in the receiver of an air-pump, and suspended the
cockroach exactly over it. As the reader will fully have surmised, my
idea was, first to exhaust the air from the inside of the insect, then
to plunge it into the mercury, and then to admit the air, which, at a
pressure of fifteen pounds to the square inch, was likely to drive the
mercury into the smallest of tubes. Such a plan was very successful with
ordinary tissues, and might succeed with insects.
Accordingly, I exhausted the air from the vessel in which the cockroach
was placed, and kept it in a state of exhaustion for a whole day, so as
to prove that every particle of air was withdrawn from the insect. I
then plunged the cockroach deeply beneath the mercury, and admitted the
air, hoping that the severe pressure would drive the mercury into the
respiratory vessels. But not one particle of the mercury could pass
through the wonderful filter with which the cockroach had been provided,
and, except that I had learned the power of the spiracle, I might have
saved both the time and trouble.
It is worthy of notice that, almost countless as are the species of
insects, no two of them possess exactly the same structure of the
spiracles, the individuality being marked as clearly in these tiny
organs as in the entire insect.
USEFUL ARTS.
CHAPTER V.
THE PRINCIPLE OF THE SPRING.--THE ELASTIC SPRING.--ACCUMULATORS.--THE
SPIRAL SPRING.
Springs and their various Structure.--The Elastic Spring.--The
Boy’s Catapult and its Powers.--The Pistolograph, its Principle,
and Uses to which it can be put.--Leaf-rolling Caterpillars, and
their Way of Work.--The Carriage Spring.--The Horse’s Hoof and its
complex Structure.--Fungi and their united Power.--The Chinese
Cross-bow.--The ancient Balista.--Skull of the Crocodile.--Bones of
young Children.--The Spiral Spring and its many Uses.--The
Toy-gun.--The Needle-gun.--Valved Brass Instruments.--Watch and
Clock Springs.--The Bed Spring.--Parallels in Nature and
Art.--Buffers of Railway Carriages.--Spring Solitaires.--The Bell
Spring.--Spiral Springs in Vegetable Tissues.--Poison Cells of
various Marine Animals.--Effects of the Spiral Springs.
ELASTIC SPRINGS.
Here we come upon a subject so large, that it is difficult to define its
exact requisite limits. The principle of the elastic spring pervades all
Nature, and the numerous adaptations in Art are closely, though perhaps
not directly, attributable to the wide distribution of the spring in
Nature.
There is, for example, the simple elasticity which enables a tree, when
bowed by the wind, to spring back so soon as the pressure is removed,
and which, indeed, is the power which enables a bow to propel an arrow.
Then there are spiral springs innumerable, many of them so minute that
they can only be seen by the aid of the microscope, and there are many
springs which exhibit their elasticity by their power of extension and
shortening, just as is done with the elastic fabrics which are so much
in vogue at the present day, and which seem so necessary to ordinary
comfort that we feel disposed to wonder how our forefathers managed
without them.
We will now proceed to examine some of these springs in detail.
* * * * *
THERE is one form of elastic spring which has of late years become more
familiar than agreeable, namely, the toy which is learnedly called a
“catapult,” though it has little in common with the ancient weapon whose
name it bears.
As may be seen by reference to the illustration, it consists of one or
more india-rubber straps attached to a fork-like handle, and carrying a
small pouch in which is contained the missile. Although it is not
remarkable for accuracy, it can throw a stone or a bullet a considerable
distance, and its power can be very quickly increased by adding to the
number of the straps. Thus a catapult has been made which was capable of
sending a small pistol bullet through a wooden board, so that the
child’s toy might really become a dangerous weapon.
Indeed, cases are known where the catapult has hurled a stone with fatal
effect upon human beings. In my own neighbourhood there are many
examples of glass being pierced by stones thrown from catapults just as
if they had been subjected to bullets shot from firearms, the holes
being quite small and round.
The power of accumulating force by increasing the number of springs was
utilised by Mr. Scaife, when he invented his wonderful photographic
machine which he termed the “Pistolograph,” on account of the sound
which was produced when the portrait was taken.
The idea was simple enough, though the practice of it was not so easy.
He wished to be able to take a photograph with an exposure of the least
possible time, and thus to attain freedom and action, instead of the
dull stiffness which generally characterizes photograph portraits. The
mode which he adopted was by introducing a peculiarly sensitive film,
which would take an impression in a mere moment, and then arranging the
machine so that an exposure of more than a moment was impossible.
This was done by covering the lens with an exactly fitting door,
revolving on a pivot. The axis on which the door revolved was attached
to a number of india-rubber bands, exactly like those which are used for
confining papers. As the power of the springs increased with their
number, it naturally followed that the rapidity of the revolution was in
exact ratio with the number of the bands, so that the duration of
exposure to light could be measured with tolerable accuracy.
So wonderfully well did this plan succeed that photographs of eclipses
were taken with perfect accuracy, a matter of great importance when time
has to be considered. Horses were also taken at full gallop, so as to
display their action, and the crowning achievement was the photographing
of a cannon in the act of firing, and the bursting of a charged shell.
So rapid is the action of the instrument, that in several cases where a
cannon or mortar had been photographed, even the track of the ball or
shell is visible.
[Illustration: LEAF-ROLLING NESTS.]
[Illustration: CATAPULT.]
It necessarily followed that when the springs caused the circular cover
to revolve with such rapidity, they made it close with a sharp report,
and so gave rise to the name of the machine. Moreover, as it had to be
used for rapidly moving objects, it was not fixed on a pedestal, but was
held in the hands, while aim was taken at the object, just as with a
pistol. When the observer thought that he had his aim correct, he
touched a trigger, round spun the cover, and the photograph was taken.
* * * * *
ON the right hand of the illustration is seen the Catapult, made with
several springs, and on the left is shown an example of the Accumulator
as formed by Nature.
The reader may probably be acquainted with the Leaf-rolling
Caterpillars, of which there are so many. I had often inspected these
curled leaves, and, on comparing them with the size of the
caterpillars, had noticed that the muscular strength of the insect was
quite inadequate to the work which was done. That much of it was owing
to the “bowsing” system, which has already been described when treating
of the Toggle-joint, was very probable, but that some other force must
be employed was evident.
On unrolling a leaf, the hidden force was at once explained, and showed
itself to be a system of accumulators exactly like those of the
pistolograph or the catapult. The caterpillar spins successive belts of
silken threads, and affixes them to the leaf, as shown in the
illustration. These threads are nearly as elastic as the india-rubber
bands of the catapult, and accordingly draw the leaf together. Another
set of belts is added above the former, and, as they harden and contract
in the air, they roll the leaf still further. The first row is then
shortened and tightened, and a third and fourth row are added in the
same fashion. So elastic are these belts, that if the leaf be carefully
handled it can be almost wholly unrolled, and will spring back again as
soon as the force is removed.
* * * * *
ANOTHER form of accumulated force may be seen in the ordinary Carriage
Spring, one of which is shown in the illustration. It is made of a
number of strips of elastic steel lying upon each other, and suffered to
play upon each other by means of slots and rivets. The weight being
placed in the centre, it is evident that this very ingenious spring is
really an elastic girder, yielding to sudden pressure, and recovering
itself when that pressure is removed.
* * * * *
INGENIOUS as is this spring, it has many parallels in Nature, one of
which is here given.
It is popularly thought the hoof of the horse is a solid mass of horn
destined to protect the feet against hard and rough ground. Such
certainly seems to be the opinion of farriers, who, in shoeing horses,
act exactly as if the horn of the hoof were structureless; whereas it is
a marvel of complicated mechanism. On looking at the exterior of a
horse’s hoof, it will be seen to be marked with a vast number of very
fine, but easily visible longitudinal lines, looking as if they were
scratches from a very fine needle. If the hoof be removed from the
foot, and examined upon the interior, it will be seen that each of the
apparent scratches signifies the edge of a very thin plate of horn, not
so thick as the paper on which this book is printed. The hoof, in fact,
is built up of multitudinous plates of horn, set side by side, and each
acting as a separate spring. It is this beautiful structure which allows
the horse to tread without a jar being sent through its whole system by
every step which it takes.
A similar structure is to be found in all hoofed quadrupeds, and is
especially noticeable in the case of the Elephant. All those who have
watched the walk of an Elephant, no matter what its size may be, must
have been struck with the curious noiselessness of its movements. Its
weight may be measured by tons, and yet the enormous animal steps as
noiselessly as a cat. On examining one of the hoofs, after it is removed
from the foot, the cause of this marvellously silent tread is perfectly
evident. The whole of the hoof is composed of nearly parallel horny
plates, and by their united action they produce the required result.
[Illustration: HORSE-HOOF.]
[Illustration: CARRIAGE SPRING.]
Each plate in itself is very feeble, but, when united as they are at the
ends, they afford mutual support to each other. Similarly the separate
feathers in a couch would be crushed by a comparatively slight weight,
but when a number are confined together they support each other, and
form the soft, yielding couch with which we are so familiar. Horsehair,
when used as the stuffing for a couch or chair, acts in the same way,
and so do the fine filaments of wool when used under the name of
“flock.”
Another good example of the power of accumulated force, although it has
no direct relation to the spring, is the well-known fact that fungi,
which are separately so fragile, are capable of lifting and retaining in
the air stones so large that two men could hardly carry them. Were the
stones laid down upon the fungi, the latter would be crushed, but, as
they grow beneath the stones, they accumulate their powers, and slowly,
but certainly, raise the weight from the ground.
* * * * *
THIS very principle of accumulated force has long been used in weapons
of war, and I possess several examples of such weapons. One of them is a
Chinese repeating Cross-bow, which was taken at the capture of the Peiho
Fort, and was really a formidable wall-instrument, carrying a reserve of
arrows, and delivering them with great rapidity. In point of fact, it
consists of three bows, placed upon each other, and playing upon each
other just as do the portions of a carriage spring. Such strength is
thus obtained, that the bow cannot be drawn by hand, but is worked with
a lever, as shown in the illustration. The whole machinery of the
weapon, including the self-notching and self-supplying system, is very
interesting, but is outside our present object. The very powerful bow of
the ancient Balista was made on the same principle, and was strong
enough to throw large stones and wooden beams.
[Illustration: JAWS OF CROCODILE.]
[Illustration: CHINESE CROSS-BOW.]
I also have bows in my collection which are strengthened on the same
principle, though not exactly in the same manner. There are several
Indian, Chinese, and Japanese bows which are curved almost like the
letter C, and have to be reversed when strung. These bows are of no very
great size, but possess wonderful elasticity. They owe the latter
quality to sundry layers of sinew which have been affixed to the back
when wet, and which add enormously to the power of the bow, while they
very little enlarge its dimensions.
Another bow, made by the natives of Vancouver’s Island, has the back
strengthened by a number of cords spun from sinew fibres, and possessing
the strength and elasticity to which we are accustomed in the strings of
the harp, guitar, or violin.
* * * * *
WE will now turn to a parallel in Nature. This is to be found in the
lower jaw of the Crocodile, as is pointed out by Professor Owen, in his
work on the “Skeleton and the Teeth.”
All persons who have a smattering of anatomy are aware that even in the
human body the most solid bones of the adult were originally composed of
several pieces, and that they only become fused together in course of
time. The jaw-bones, for example, were once so composed, and in the
Crocodile the junction is never completed, the pieces of bone remaining
separate, but being pressed firmly against each other during life.
I have now before me the skull of a Gangetic Crocodile, in which,
although the animal was an adult when killed, the bones of the long
lower jaw are so loose that unless they were tied together the jaw would
fall to pieces.
This analogy between Art and Nature is thus described by Professor Owen
in the work which has just been mentioned:--
“The purpose of this subdivision of the lower jaw-bone has been well
explained by Conybeare and Buckland, by the analogy of its structure to
that adopted in binding together several parallel plates of elastic wood
or steel to make a crossbow, and also in setting together thin plates of
steel in the carriage spring.”
Dr. Buckland also adds: “Those who have witnessed the shock given to the
head of a Crocodile by the act of snapping together its thin, long jaws,
must have seen how liable to fracture the lower jaw would be were it
composed of one bone only.... The splicing and bracing together of thin
flat bones of unequal length and of varying thickness afford
compensation for the weakness and risk of fracture that would otherwise
have attended the elongation of the parts.”
A good example of the value of this structure of bone may be found in
young children. Before they are old enough to take care of themselves
they are perpetually falling down, and never hurting themselves. I have
seen a little girl of five years old roll from top to bottom of a lofty
staircase. It looked as if the child must be killed, but she was only
giddy with her many revolutions, and a little bruised about the elbows.
The reason of this curious immunity from injury is, that the bones,
especially those of the skull, are not completely united, and so act on
the principle of the compound spring.
THE SPIRAL SPRING.
This subject is so large, and there are so many examples, both in Art
and Nature, that it is not very easy to make selections which will
sufficiently answer the purpose.
[Illustration: WATER-LILY. LILY. POISON-CELL OF HELIANTHOID.
ANTHEROZOIDS.]
[Illustration: SPIRAL SPRING. BED SPRING. WATCH SPRING.]
The upper left-hand figure of the illustration represents the ordinary
Spiral Spring made of wire, and used for its power of resuming its shape
when compressed. In early childhood most boys have had practical
experience of this spring in the toy guns and cannons with which they
are supplied. The spring is compressed by the ramrod, and held in its
place by a catch. If a pellet be placed in the gun, and the catch
released by pulling the trigger, the spring flies back to its former
shape, and drives the pellet.
An exactly similar spring is used in the well-known “Needle-gun,” the
spring driving a needle through the explosive mixture, and so igniting
the charge.
Our brass instruments would be very badly off without the spiral spring,
which is placed under the pistons. The elasticity allows the pistons to
be pressed down, and when the fingers are raised the pistons spring up
again.
Another form of this instrument is seen on the right of the ordinary
spring. This is used in the manufacture of spring mattresses and
couches, and is made thinner in the centre, so as to allow of greater
elasticity.
Below them is the spring which is used for watches and clocks, one end
being fastened to the rim of the barrel, and the other to the pivot.
When the latter is turned the spring becomes “wound up,” and, when
released, keeps the works going by pressing against them. Of the
“pall-and-ratchet” wheel, by which the movements are retarded, we shall
treat in another place.
* * * * *
ON the left hand of the illustration are a few figures of the Spiral
Spring as seen in Nature.
On the extreme left of the group is a spiral cell taken from the
flower-stem of the Water-lily. As the reader will see, it is composed of
a number of fibres laid parallel to each other, and twisted into a
hollow spiral. In order to exhibit its shape the better, the spiral has
been partially uncoiled.
On the extreme right is a corresponding spiral cell from the common
Lily, in which the spring power is given by two fibres twisted in
opposite directions. The reader will now understand and admire the
mechanism by which these plants attain their great strength and
elasticity, the stems being made of myriads of these spiral fibres.
The oval body on the upper part of the illustration is a poison-cell of
a marine polyp, and is given here as an example of an animal spiral
spring, the others all belonging to the vegetable world.
We shall see more of its structure a little further on, and will not now
examine it in detail.
The two remaining figures represent the remarkable objects called
Antherozoids, _i.e._ the living creatures of anthers. They exist in vast
numbers in the non-flowering plants, and inhabit those parts which
correspond with the anthers of the flowering plants. When placed in
water they have a curious way of coiling and twisting themselves
spirally, so as to make their way through the water in a tortuous, but
tolerably rapid, course. This movement is effected by the contraction
and expansion of the spirally twisted filament. The upper figure
represents a group of Antherozoids in their cells, and the lower is a
much more magnified figure of a single Antherozoid as it appears when
free, and in the act of moving through the water.
* * * * *
ON the accompanying illustration are many examples of Spiral Springs,
both natural and artificial. We will take these in their order.
The upper left-hand figure represents the “Buffer,” by which the
carriages of railway trains are prevented from jarring against each
other.
Perhaps some of my readers may be old enough to remember the days of the
old railway carriages that were connected by short chains, and furnished
with buffers that were merely padded. As the train started a separate
jerk was given to every carriage by the tightening of the chains, and,
as it stopped, all the carriages bumped against each other in a most
unpleasant manner. Now, however, the buffers are furnished with powerful
springs, and are pressed strongly against each other by means of
screw-bolts, so that they form one continuous line.
In fact--and here is another analogy between Art and Nature--a train,
when properly made up, bears a close resemblance to a human spine, the
carriages being analogous to the vertebræ, and the spring buffers to the
elastic cartilages between the vertebræ.
Nowadays, owing to this arrangement, the whole train moves together, and
can be started and stopped so gently that the passengers are hardly
aware of movement or stoppage. For example, one of my friends was in a
train which came into collision with some obstacle. The carriages in
front were dashed to pieces, and several of the passengers killed. His
carriage, however, which was nearly at the end of the train, and had the
benefit of all the springs, was hardly shaken, and the inmates did not
know for some little time that an accident had occurred.
[Illustration:
BUFFER OF RAILWAY ENGINE. MOSS DISCHARGING SPORES.
SUPPORTING SPRING OF RAILWAY CARRIAGE. TENTACLE, WITH SPRINGS.
SPRING SOLITAIRE. SPRING-CELL OF MADREPORE. SPRING-THREAD OF
SEA-ANEMONE. SPRING-CELL OF CORYNACTIS.
BELL SPRING.]
Below the buffer is a Wheel Spring, made exactly on the same principle,
but set perpendicularly instead of horizontally.
* * * * *
THE two figures beneath the wheel spring represent an object very
familiar to us, namely, a Spring Solitaire, one figure showing it as
open, and the other as closed. In this article the clasp is held in its
place by a spring, and is only released by pressure.
* * * * *
BELOW the solitaire is a very prosaic application of the Spiral Spring,
namely, that by which a house-bell is kept in vibration after the force
of the pull has ceased, and which renders the bell, as Dickens happily
remarks, so greedy to ring after it has been pulled.
I made and employed a spring of a similar character in closing the door
of my parrot’s cage. Polly is a wonderfully clever bird, and a capital
talker. First, she had a cage with upright bars, two of which could be
slid upwards by way of a door. She soon found out the trick of the bars,
and used to escape, carefully replacing the bars afterwards.
When she was transferred to a metal cage, she discovered that the door
slid upwards, and began at her old tricks. So I took a piece of
galvanised iron wire, coiled it into a spiral spring, fastened one end
to the upper part of the door, and the other by a hook to a staple at
the bottom of the cage. Consequently, when Polly lifted the door, and
loosened her grip for a fresh hold, the door closed itself again. So,
after awhile, Polly gave up the door, and now never tries to open it.
* * * * *
PASSING to the upper right-hand corner of the illustration, there is
shown a portion of Moss as it appears when magnified, and discharging
its spores. When they are ripe a vast number of little spiral springs
are let loose, and shoot the sporules into the air.
* * * * *
BELOW the moss are four figures, which are, in fact, the same object
differently magnified, and seen from different points of view. These
peculiar organs are technically termed “cnidæ,” from a Greek word which
signifies a nettle. The appropriateness of the name we shall presently
see.
I have already mentioned that the tentacles of various marine animals
are furnished with poison-cells. The object of these cells is to
capture and kill the prey, and the mode of doing so is very remarkable.
On the right and left of the illustration are two such bodies, in which
is seen a sort of elastic wire coiled spirally, apparently without
regularity, but really possessing a most beautiful order. That on the
left is the poison-cell of a Madrepore, and the other is the same organ
in a Corynactis. No sooner is the tentacle touched than the poison-cells
are mechanically acted upon. They are turned inside out, and the coiled
spring darts forth with wonderful violence.
Slight as is the dart, so fine that it cannot be seen except with the
aid of a tolerably powerful microscope, it is a terrible weapon.
Although it is projected with sufficient force to bury itself to its
base even through so tough an object as the human skin, it could inflict
but little injury, and would, indeed, scarcely be felt. But it carries
with it a most irritant poison, which is apparently contained in the
little capsule. These cnidæ are very plentiful in the tentacles of the
Stinging Jelly-fish, or Stanger, as it is often called, and are charged
with a terrible poison.
As is the case with all such poisons, its effects differ according to
the constitution of the being that is poisoned. There are some persons,
for example, who care no more for the sting of a bee than for the prick
of a needle, and there are those whom a single bee-sting will bring
almost to the gates of death. So with the tentacles of the Stinging
Jelly-fish and those of the Portuguese Man-of-war, and there are persons
who are scarcely affected with the sting of the scorpion.
So it is with nettles. When I was a boy at school it was thought
necessary to wear an oak-leaf, or at least a portion of an oak-leaf, on
the 29th of May, and all who did not possess this talisman might be
flogged with nettles by those who did. As the school was situated in the
north of England, where the oak puts forth its leaves late in the
season, it was no easy matter to obtain a veritable oak-leaf, and we
used to take any leaf that we could procure, and cut it round the edges
into the similitude of a suitable oak-leaf.
The effect of the nettles upon the boys was most curiously diversified.
Some cared nothing whatever for them; others suffered sharp but brief
pangs; while others, of whom I was one, endured the most lancinating
pain at the time, and for hours afterwards a hot, burning, fevered skin,
and a heavy, dull ache, accompanied by throbbings of the brain so
violent that it appeared as if the head would burst asunder at every
heart-beat.
The fact of this inequality has been throughout life a valuable lesson
to me, _i.e._ that a punishment which will nearly, if not quite, kill
one man, will be no punishment at all to another.
Of course I cannot answer for the effects of these very minute cnidæ
upon others, but I can state that they nearly killed _me_, and that if I
had been forced to swim another hundred yards, I should have collapsed,
sunk, and had a coroner’s jury return a verdict of “Found drowned in
consequence of cramp.”
On me the effects were as follows:--First a slight, and then a severe,
tingling on the parts which had been struck. Then sharp, darting pangs.
Then a sudden shock as if a bullet had passed through the breast from
one side to the other. Consequent collapse, and suspension of the office
of both heart and lungs. I once had to walk nearly two miles after being
stung by one of these dread animals, and how often I fell before
reaching my lodgings I dare not say, but certainly once in every two
hundred yards.
Even after partial recovery I should not have known my own face. It was
that of an old and wearied man of seventy, grey, wrinkled, and withered;
and many months elapsed before I felt myself sure that the weird-like
bullet would not drive through my breast, and leave me lying on the
ground gasping and speechless.
These dreaded tentacles can sting as fiercely when separated from the
animal as when they are conjoined to it, as I can also testify from
personal experience.
I have a natural alacrity in damaging myself, and there is scarcely a
representative bone in the body that I have not fractured or dislocated,
or both. Fortunately the cerebral vertebræ have hitherto escaped. I have
broken the right leg, right arm, two ribs, and right collar-bone;
dislocated the right ankle, and smashed nearly every bone of the right
hand. At present, the damage to the left side is restricted to two ribs;
and I hope that the Genius of Ossifraction may now be content with his
work.
But I equally seem to have a natural affinity for the tentacles of the
Stangers, which deliver their envenomed darts just as fiercely when they
are separated from the Medusa as when they are connected with it.
A curious example of this fact befell me in the present year (1875).
Seeing that there had been a steady southern gale, which made Lundy
Island and Hartland and Baggy Points indiscernible, I dreaded my old
foes, and, instead of bathing from the “Pebble Ridge,” took to the great
“Nassau” Baths at Westward Ho. I sadly missed the roll of the waves, and
the placid rapture of lying with outspread arms as the vast Atlantic
billows came rolling in, flinging up the great grey boulders as if they
were corks, and letting them roll down the ridge again with a
thundering, and yet soothing, sound. Three miles or more inland may the
thunder of the Pebble Ridge be heard; and at night, even though a storm
be raging, tearing the leaves off the trees in whirling showers,
flinging great branches into the air like ostrich plumes, and howling so
that one person can hardly hear another speak, the dull, low, continuous
thunder of the Pebble Ridge is heard over all. I have often remained
awake at Bideford, simply on account of the deep roar of the Pebble
Ridge, as the rising tide rolled its vast waves along the coast from
Baggy Point, through Westward Ho and Clovelly, to Hartland.
When there is a heavy sea, the “undertow” of these waves is so great
that even had no such things as Stangers existed, I should not have
ventured upon the Pebble Ridge. One of my friends, a strong swimmer, was
nearly drowned off that ridge by the undertow; and not long before I
visited Westward Ho a promising young man lost his life within a few
yards of that treacherous shore.
Much against my will, I went to the new bath, which is always supplied
with a running current of sea-water; and I had hardly swum the length of
the bath before I felt the familiar nettle-like sting in my foot.
Fortunately it was only caused by a small fragment of a Stanger’s
tentacle, which had been severed from the animal and pumped into the
bath, and no harm ensued.
USEFUL ARTS.
CHAPTER VI.
SPIRAL AND RINGED TISSUES.--VARIOUS SPRINGS IN NATURE AND ART.
Spiral Tissues, and their Structure and Uses.--The movable
Gas-lamp.--Elastic Tubes.--Breathing-tubes of Insects, and their
Spiral Wire.--Ringed Tissues and their varied Structure.--Ringed
Tissues applied to modern Dress.--Chinese and Japanese
Lanterns.--Proboscis of the House-fly.--Trachea of various
Animals.--Mutual Tendency of Rings and Spirals towards each
other.--Fibres of the Yew-tree.--Diving and Divers.--Principle of
the Diving-bell.--How it is supplied with Air.--Structure of the
Air-tubes.--Nests of the Water-spider.--Diving by means of
Tubes.--Larva of the Drone-fly, and its Mode of breathing.--How to
examine them.--Leaping Springs.--The Skip-jack in Nature and
Art.--Skip-jack or Click Beetles.--The Spring-tail, Grasshopper,
Kangaroo, Gerboa, and other Jumping Creatures.
SPIRAL AND RINGED TISSUES.
We have now to consider the Spiral Tissue under another aspect, _i.e._
that of acting as the internal support of an exterior membrane. Ringed
tissues are necessarily conjoined with the Spiral, as they both
discharge the same office, and in some cases merge almost imperceptibly
into each other in the same specimens. This is most beautifully shown in
the proboscis of the common House-fly, to which reference will presently
be made.
The subject is so large that only a comparatively small selection of
examples can be made, the greater number belonging to Nature, and not to
Art.
We will first take the common movable Gas-lamp, with its accompanying
tube. It is at present the tube of which we have to treat, the gas
itself being reserved for a future page.
It is necessary that, in order to enable the lamp to be moved from one
spot to another, the tube through which the gas passes must be so
constructed that if it be bent, or even coiled, it retains its form, and
does not become flattened. In order to obtain this object, a very long
thin wire is coiled spirally to a suitable length. Over this wire is
sewn the casing of the tube, which is afterwards made waterproof with
elastic varnish. A still simpler mode is by enclosing a spiral wire
within a tube of vulcanised india-rubber. It will be seen, then, that by
the elasticity of the spiral wire the tube must always retain its shape,
no matter how much it may be bent.
On the right hand of the illustration are shown the movable Gas-lamp and
tube, and a portion of the latter is given with its spiral wire
partially unwound, in order to show its structure.
[Illustration: TRACHEA OF INSECT, WITH ITS SPIRAL THREAD.]
[Illustration: TUBE OF GAS-LAMP, WITH ITS SPIRAL WIRE.]
The large tubes which convey air to divers are made in the same manner,
as they would not only succumb to the pressure of the water without the
wire, but could not be dragged over obstacles or round corners without
collapsing. It often happens that a diver is obliged, when surveying a
sunken ship, to traverse the whole of her interior, descending ladder
after ladder, and entering every cabin in the ship. This could not be
done but for the internal coil of wire within the tube. Reference will
presently be made to the subject of diving.
* * * * *
ON the left hand is seen an object that looks something like a branch
hollowed very thin. It is a magnified view of part of the Trachea or
breathing-tube through which air is conveyed into the system of an
insect. These breathing-tubes ramify to every portion of the body of an
insect, even penetrating to the extremities of the antennæ, the wings,
and the legs. It is obvious that as these organs are in tolerably
constant movement, and the legs are much bent at every joint by the
action of walking, the air-tubes which run through them must possess the
same qualities as those of the gas-lamp and diver.
If one of these tracheæ be removed and placed under the microscope, it
will be seen to be constructed in a manner exactly similar to that which
has been described. Within the membrane which forms the tube proper
there is a very fine, but very strong thread, which is coiled exactly
like the wire spring. It is not attached to the membrane, and so strong
is it that, although it is all but invisible to the naked eye, it can be
drawn out as shown in the left-hand figure of the illustration. If laid
on a piece of glass, it immediately tries to recoil itself, and for some
little time will twist and curl about as if it were alive.
[Illustration: TRACHEA OF DRAGON-FLY LARVA.]
[Illustration: TUBE OF HOOKAH.]
* * * * *
ON the above illustration are two similar examples of the spiral thread
with a flexible tube. The right-hand figure represents one of the many
forms of the water-pipe, whether known as Hookah, Narghile, or
Hubble-bubble. In the simpler forms of this pipe, such as the latter,
the inhaling-tube is quite straight, and the bowl is held in the hands
of the smoker. In the more refined pipe, however, the tube is very long,
flexible, and made elastic by an inner spiral wire.
Perhaps the reader may remember that the larva of the Dragon-fly is a
most remarkable creature in consequence of its methods of propulsion
and respiration. The water is taken into the interior of the body
through a peculiarly formed aperture, and then ejected with such
violence as to drive the body forward on the same principle as that
which causes a rocket to ascend.
The figure on the left hand of the illustration is a representation of
the abdomen of this larva rather magnified, and opened so as to show the
interior. On either side run the two principal breathing-tubes, through
the delicate membranes of which the spiral thread can plainly be seen.
These tubes are connected with a smaller set, and they with a still
smaller, so that at last they are of such tenuity that they can scarcely
be distinguished without the use of a glass. But, however small they may
be, they are always fitted with the spiral thread.
* * * * *
WE now come to the cases where the membrane is supported by a series of
rings, and not by a single spiral wire.
In the right-hand division of the illustration are two specimens of
objects which shall be nameless, but which were drawn per special favour
at a milliner’s shop. Although the day has now happily gone by when the
larger object was in general wear, and seemed to be irrepressively
increasing in dimensions, certain modifications of it, under various
names, have made their appearance in almost every book of fashions and
every large milliner’s shop.
Here we have the external membrane made of linen, calico, merino, or
similar material, distended by a number of elastic rings set at
tolerably even distances from each other.
The two small objects represent the handy little paper lanterns so
common in China and Japan. They are composed of an external coat of
tough tissue paper, so thin that it allows the light to pass through it
with tolerable freedom, and of an internal series of elastic rings,
which not only support it and preserve its cylindrical shape, but allow
it to be folded up flat when not wanted.
I possess a singularly ingenious lantern of this kind, made in Japan,
and displaying the thoroughness of work which characterizes that nation.
It is five inches in diameter, and the lantern itself is affixed at
either end to a circular wooden cap the upper fitting over the lower.
Consequently, when the lantern is shut, it is entirely enclosed between
these two caps, which effectually preserve it from harm. It is
delicately finished, and has no less than thirty rings, made of very
narrow strips of bamboo. The upper cap has a little trap-door through
which the candle can be admitted and trimmed, and in its centre is a
small round hole for the passage of air.
* * * * *
IN the left-hand division of the illustration are shown several examples
of ringed and spiral tissues belonging to the vegetable world, in which
the principle is exactly the same as that of the Chinese lantern, &c.
That on the right hand is an example of simple rings within a membrane.
The central figure shows a double spiral, which produces very much the
appearance of a series of rings; and on the extreme left is an
interesting example which shows the transition in the internal supports
from spirals to rings.
[Illustration: SPIRAL AND RINGED FIBRE (VEGETABLE).]
[Illustration: NAMELESS OBJECTS.]
[Illustration: PAPER LANTERNS.]
I have already mentioned that the proboscis of the House-fly exhibits
this modification. If one of these objects be placed under a moderate
power microscope--the half-inch is quite enough--and examined, it will
be seen that there are some large tracheæ, just like those of the
Dragon-fly larva, on each side of the proboscis, and that, where the end
is widened and flattened into a sort of disc, their place is taken by a
set of very much smaller tracheæ, coming nearly to a point, and each
being supported internally by a series of incomplete rings, shaped very
much like the letter C. A slide containing this object well mounted can
be purchased at any optician’s for a shilling.
* * * * *
THE trachea, or windpipe, as we call it, of all vertebrate animals, man
included, is formed on exactly the same principle, as any one may see by
going to a butcher’s shop, and looking at the trachea, or windpipe, by
which the lungs, or “lights,” as they are called, are suspended. Were it
not for this structure, we should not be able to bend our necks or turn
our heads.
[Illustration: OX.]
[Illustration: PIG.]
[Illustration: GOOSE.]
The accompanying illustration shows the tracheæ of three well-known
creatures. The left-hand figure is the trachea of an Ox, the central
figure that of a Pig, and the right-hand figure that of a Goose. Mr.
Tuffen West, who made the drawings, sent with them the following
remarks:--
“The tracheæ of animals furnish some very interesting examples of
variation in the form and arrangement of the rings. Their purpose,
perhaps, one can but guess at in some cases; but doubtless, as being
works of the Master Builder, careful study would be repaid.
“In the Ox the rings are very strong and close, and in form like a
horse-shoe with the ends approximated.
“In the Pig the incomplete rings are broad at one part, and narrow on
the opposite side, with a tendency to spiral arrangement. I imagine that
this would make a very rigid tube, and, indeed, it feels so in the hand.
“Then, in the Goose, the narrowed lower part is that which is figured
just before the trachea reaches the sternum. The (complete) rings are
twice as broad in one half as in the other, and by the alternate
disposition of these differing widths, a tube is formed of great
flexibility fore and aft, but almost absolutely rigid in the lateral
direction. This seems to be so marked an evidence of design as to be
calculated to greatly raise our admiration.”
[Illustration: RINGED TISSUES OF SUGAR-CANE]
[Illustration: VEGETABLE SPIRAL TISSUES TENDING TO RINGS.]
* * * * *
WE have seen several examples of ringed tissues tending to the spiral
form, and it is but natural that we should expect to find spiral tissues
tending to the ring.
In the accompanying illustration the two left-hand figures represent the
curiously modified ringed tissue which is to be found in the sugar-cane,
the left-hand figure being much more magnified than the other.
The other figures represent four examples of vegetable spiral tissues,
in which it will be seen that there is a tendency to form rings, and
that if a number of rings were substituted for the spiral, and the
object viewed in a slanting direction, it would be almost impossible to
distinguish between the ring and the spiral.
Among the most remarkable of these examples are the two right-hand
figures. That on the extreme right represents a spiral vessel taken from
the so-called root, or “rhizome,” of the Water-lily, and the other is a
similar vessel taken from a branch of the Yew-tree. It has been
suggested that to this spiral structure is due the proverbial elasticity
of the yew-tree, which has from time immemorial rendered it the best
wood for the manufacture of bows.
DIVING AND DIVERS.
It has already been mentioned that the flexible tubes used by modern
divers are constructed on the model of several structures belonging to
the animal and vegetable kingdoms.
We will now see how they are utilised.
* * * * *
IN the earlier stages of the diver’s art the Diving-bell afforded the
only means of gaining access to the bed of the sea, even in
comparatively shallow waters. The mode in which this result was obtained
was simple enough, and though it carried with it the germs of still
greater improvements, was but limited and uncertain in its action.
The reader is probably aware that if a vessel be filled with air, no
liquid can obtain admittance until a corresponding amount of air be set
free. Suppose, for example, that an empty tumbler be inserted over a
basin of very clean water, and pressed downwards, it will be found that
scarcely any water will enter it, the air having taken up all the
available space, and only allowing as much space as may be accounted for
by its faculty of compression.
It is evident, therefore, that if an enlarged tumbler could be lowered
to the bed of the sea, a man might be enclosed within it, and for a time
be able to support life by means of the air contained within the “bell,”
as this enlarged tumbler was popularly called.
It is equally evident that within a short time the air within the bell
must be exhausted, and that, unless a fresh supply could be introduced,
the diver within the bell would be as effectively drowned as if there
were no bell at all.
The accompanying illustration is a kind of chart, so to speak, of the
mode in which air was formerly supplied to the bell.
On the right hand is seen a section of the Diving-bell itself, together
with the seat on which the divers can rest. There is also an
escape-valve at the top of the bell, by which the vitiated air can pass
away; but, as it is not essential to the subject in hand, and is rather
complicated in structure, it has been omitted.
Immediately on the left of the bell is a cask, to which several heavy
weights are attached. This cask contained compressed air, and, after it
was lowered by the side of the bell, the end of the flexible tube was
taken into the bell, the tap turned, and the compressed air rushed into
the bell, taking the place of that which had been exhausted by
respiration, and was allowed to pass through the escape-valve. I may
mention that the divers unexpectedly discovered that, when they were
breathing compressed air, they could dispense with respiration for a
wonderfully long time, the amount of oxygen taken in at a single breath
being enough to renovate the blood more than could be done by several
ordinary inspirations.
[Illustration: NEST OF WATER-SPIDERS.]
[Illustration: DIVING-BELL.]
On the left hand of the illustration is seen a sketch of the nest of the
now familiar Water-spider (_Argyronetra aquatica_), taken from some
specimens in my possession.
The Water-spider is really a remarkable being. Itself a denizen of air,
breathing our earthly atmosphere just as we do, and as capable of being
drowned as ourselves, it nevertheless passes nearly the whole of its
existence under water, and in that strange locality lays its eggs and
rears its young. How this wonderful feat is performed we shall now see.
When the female Water-spider wishes to deposit her eggs, she looks out
for a suitable locality, and, being a good diver, tests the various
aquatic herbage until she has found a favourable spot, and then sets to
work on her remarkable nest, which I believe is quite original in
zoology.
After stretching a few stout threads by way of a scaffolding, she
attaches to the plant a small silken cell, shaped very much like an
acorn, but not so large. Ascending to the surface of the water, she
contrives to clasp a bubble of air between her last pair of legs, and,
laden with this airy treasure, dives below.
As soon as she has reached the entrance to the cell, which is always
below, she loosens her hold of the air-bubble. It at once rises into the
cell, and expels a proportionate amount of water. Not many of these
journeys are required before the nest is filled with air, and then the
diminutive architect spends the greater part of its time in holding on
to the mouth of the little diving-bell, and supporting life by means of
the air within it.
This nest, as the reader will see, is an exact representation of the
various diving schemes in which air-bells are the chief portions of the
machinery, although the air is conducted into them after a different
fashion.
* * * * *
WE now come to another mode of diving, in which the bell is practically
superseded by the flexible tube, which allows to the diver far more
range than can be obtained by the bell. In this case the diver wears a
peculiar dress, the chief part of which is a helmet so constructed that
air can be introduced to it from above the surface of the water, and,
after respiration, can escape by means of a valve.
Air is pumped into the tube by assistants above water, and, as the tube
is long and elastic, the diver can move about with considerable freedom.
As is the case with the diving-bell, the diver’s tube is strengthened by
an internal spiral wire, so that it is always open, however it may be
bent or twisted.
The right-hand figure of the illustration represents the diver examining
part of a sunken vessel. The tube through which he breathes is seen
passing to the surface of the water, and so is the line by which he
gives his signals to his comrades above. In his hand he holds a lamp
which can burn for a limited time, being connected by a smaller but
similarly constructed tube to a vessel of compressed air.
* * * * *
ON the left hand of the same illustration are shown the curious Rat-tail
Maggots, as they are popularly called. They are the larvæ of the common
Drone-fly (_Eristalis tenax_), which is so common towards the end of
summer, and looks so curiously like a bee.
[Illustration: RAT-TAILED MAGGOTS.]
[Illustration: DIVER WITH AIR-TUBE.]
These creatures pass their larval life buried in the mud and below the
surface of the water, and yet are obliged to breathe atmospheric air.
This they do by means of the long appendages which have gained for them
the name of Rat-tails. These “tails” are very elastic, and are capable
of elongation and contraction to a wonderful extent.
When the creature is undisturbed, it lies buried in the mud with its
head downwards, and its tail extended so that it reaches the surface of
the water. Within this tail are two air-tubes, which are connected with
the principal tracheæ, which have already been mentioned. They are
wonderfully elastic, and, when the tail is extended to its utmost limit,
are nearly straight. When, however, the tail is contracted, the tubes
become self-coiled by their own elasticity, and shrink into the base of
the tail.
As the tail is very transparent, it is easy to see how these movements
are conducted. The larvæ, which may be found in almost any stagnant
water, should be placed in a tall and narrow glass. Some mud should be
placed at the bottom of the glass, which should then be filled with
water to the depth of three inches or so.
When the mud has quite subsided, and the water become clear, the long
slender tails of the larvæ will be seen so elongated that their tips
reach just above the surface of the water. A magnifying-glass will
easily show the two tubes within the tail.
Let the glass be but slightly tapped, and all the tail is withdrawn in a
moment, so as to be out of reach of external danger. The
magnifying-glass will then show the two tubes lying contracted in the
base of the tail, and taking astonishingly little space, considering the
amount of elongation which they can sustain. And, on examining the
various bends and curves of the tubes, the value and power of the spiral
spring will at once be seen. True, they are very small, but in Nature
all things go by comparison, and our whole earth itself is as a grain of
sand upon the seashore among the grandeurs of the visible universe.
THE LEAPING SPRING.
The last of the springs which can be mentioned in this work are those
which are used for leaping purposes.
The figure on the right hand represents the common Spring-jack or
Skip-jack with which children are always so much amused. It consists of
a flattened piece of wood called the “tongue,” which is inserted into a
twisted string, so that it forms a tolerably powerful spring. When
twisted round, and then suddenly released, it strikes against the ground
with such force that the whole machine is thrown into the air.
Sometimes the Skip-jack is made of a fowl’s merrythought, as shown in
the illustration; sometimes of the breast-bone of a goose; and sometimes
of a piece of wood cut into the semblance of a frog, and painted. In all
cases, however, the machinery is practically the same. I may mention _en
passant_ that these frog Skip-jacks are most acceptable presents to
savage chiefs in many parts of the world, and that the most powerful and
venerable warriors are as delighted with these toys as any European
child of six years old.
* * * * *
NOW we will turn to Nature, and see what she has in the way of
Skip-jacks.
All entomologists will at once have before their minds the vast groups
of Skip-jack Beetles, technically termed _Elateridæ_, and also known as
Click-beetles, from the sharp clicking sound which they produce when in
the execution of their curious gymnastics. To this group belong the
fire-flies of warm countries, and it may be mentioned that the larvæ of
some of our species are too familiar to the agriculturist under the name
“wireworm.”
[Illustration: SKIP-JACK BEETLE. GRASSHOPPER.]
[Illustration: SKIP-JACK.]
All these beetles have very short legs and very long bodies, so that if
they should fall on their backs on a smooth surface, they could not
recover themselves. Now, as they, when discovered, instinctively try to
save themselves by falling to the ground, it is evident that some means
must be used to enable them to regain their position. This is found in a
most curious apparatus.
Attached to the “prothorax” is a rather long, pointed, and very elastic
projection exactly corresponding with the tongue of the Skip-jack. The
end of this tongue fits into a groove in the “sternum.”
When the beetle falls on its back, it curves its body as shown in the
illustration, the tongue thus being freed from its groove. It then
smartly springs the tongue back into its place with the sharp clicking
sound already referred to, and does so with such force that it leaps
into the air to some height.
Generally it falls on its feet, but if it should fail, it repeats the
process. If one of these beetles be laid on a plate or similar smooth
surface, it will skip ten or twelve times without stopping, and after a
short rest will begin again.
* * * * *
THERE are some curious little beings, popularly called Spring-tails,
which afford excellent examples of the Leaping Spring. Their exact place
in the system of Nature is rather uncertain, some zoologists considering
them as insects, while strict entomologists reject them. They are very
small, and mostly of a darkish brown colour.
Plenty of them may be found under stones in damp spots, under bark, and
in similar localities, though they are often found in houses, and have
frequently traversed the paper on which I have been writing this book.
Cellars are favourite localities of theirs, and a little flour sprinkled
on a plate or piece of paper in a cellar is tolerably sure to attract
them. Although they are certainly not more than the fifteenth of an inch
in length, they may be at once recognised by their peculiar attitude,
which very much resembles that of a dog or cat in its usual sitting
posture.
As long as they are not disturbed they crawl about in a quiet manner,
but if touched, or even alarmed, they suddenly make a tremendous leap,
propelling themselves by means of a forked and elastic tail, doubled
under their bodies, and acting just like the tongue of a Skip-jack.
* * * * *
BELOW the Skip-jack Beetle is shown the common Grasshopper, as an
example of muscular leaping springs.
We all know what wonderful leaps the Grasshopper, Cricket, and all their
kin can make, the leaping movement being evidently intended more as a
means of defence than as an ordinary mode of locomotion. The same may be
observed in the Kangaroos and Gerboas, which are content to use an
ordinary walking pace when undisturbed, but when alarmed can make
tremendous leaps, and outstrip almost any pursuer.
Even in Man, the Horse, the Dog, &c., which are most essentially leaping
animals, the same principle is employed, the legs being used as muscular
springs acted upon by the will of the owner.
USEFUL ARTS.
CHAPTER VII.
FOOD AND COMFORT.
Parents and their Young.--Milk, and the various Ways of obtaining
and using it.--The Kafir Tribes and Clotted Milk.--The Tonga
Islanders.--The Tartars.--Ants and Aphides.--Honey-dew.--Milch Cows
in Insect-land.--Fish-tanks and Aquaria.--Bill of the
Pelican.--Eggs and Chickens.--The Hen-coop.--Nest of
Termite.--Workers and Queen.--Egg-hatching.--The Hen and her
Young.--Artificial Egg-hatching Machine.--The Snake and her
Eggs.--The Gad-fly and Bot-fly.--Preservation of
Provisions.--Hanging Meat.--Eggs of the Lace-wing
Fly.--Spider-eggs.--The Butcher’s Hook and the Claws of the
Sloth.--Bats and Insects.
This subject is necessarily a very large one, and I shall, in
consequence, be obliged to compress it, though it might well make a
separate work by itself. For Food represents the very existence of Man,
considered as one of the animal world; and Comfort represents the
progress of civilisation, by which man leaves day by day his savage and
solitary nature behind him, and becomes social, moral, and elevated.
* * * * *
PUTTING aside the instinct which forces the parent to feed the young
without external assistance, we come to those cases where the parent has
to seek food which the offspring could not have found for itself, and
often to prepare it for the use of the offspring.
In the greater part of the world, the milk of various animals is the
staple of food, not only for children, but adults; and the “milk diet,”
as it is called, is strongly urged by many physicians of the present
day.
The Kafir tribes, for example, a wonderfully powerful race of men, live
almost wholly on sour milk, mixed with maize flour, never eating such
valuable animals as kine except on great occasions. Yet the natives of
the Tonga Islands think that nothing can be more disgusting than for a
human being to drink the milk of a cow.
How the operation of milking is conducted we need not say, whether it be
performed on the cow as with most nations, or the ass in case of need
with ourselves, or the mare as with the Tartars, or the goat and sheep
in various parts of the world. The milk of the sheep, by the way, is
singularly rich and nourishing.
Suffice it to say that the animals which are to be milked are kept for
that purpose, and that the touch of the human hand, rightly applied,
induces the animal to part with its milky stores.
* * * * *
IN Nature there is an exact parallel.
It has long been known that some species of Ants are in the habit of
acting in exactly the same manner as ourselves, in not only extracting a
nutritious liquid from other insects, but watching and tending those
which furnish their daily food just as a good dairyman watches and tends
his cows.
[Illustration: ANT AND APHIS.]
[Illustration: MILKING COW.]
The Ants, being insects, would naturally require insect cows, and such
are to be found in the Aphides, of which mention has already been made.
These insects are furnished with a pair of very small tubercles near the
end of the abdomen, and from them flows that sweet liquid which is so
familiar to us under the name of “honey-dew.” For centuries no one knew
the source of the sweet honey-dew which attracted all the bees of the
neighbourhood to the tree on whose leaves it was sprinkled, sometimes in
patches, and sometimes coating them with a thin shining coat, as if
varnished.
At last it was discovered that the honey-dew is, in fact, the liquid
exudations from these tubercles upon the backs of the aphides, and that
the ants feed regularly upon it. Not only do they lick up the honey-dew
that has fallen from the ants, but they milk them, so to speak, exactly
as a dairymaid milks a cow. With their antennæ the ants pat and stroke
the tubercles of the aphides, and in a few seconds a drop of pellucid
liquid appears at the extremity. This is the honey-dew, and is at once
lapped up by the ant, which proceeds from one aphis to another until it
has obtained its fill of the sweet food.
How the ants carry off the aphides, cherish and guard them for the sake
of their honey-dew, is a story too long to be told, but it is well known
among entomologists. Our English ants are, however, totally eclipsed by
a Mexican species, which not only collects honey, but stores it in the
bodies of its kindred.
[Illustration: PELICAN.]
[Illustration: FISH-TANK.]
After taking precautions that no food can escape, the ants feed with
their sweet store their companion, who is thus doomed to pass the
remainder of life as a mere honey-cell. The abdomen becomes spherical,
smooth, and so transparent that the honey can be seen within it. It is
quite air-tight, and so preserves the fragrance of the honey until it is
wanted.
So plentiful are these honey-ants, that they are an article of commerce,
and are sold by measure for the purpose of making a sort of mead. There
are many of them in the British Museum, with the honey still within
their transparent bodies, and they are well worth seeing.
* * * * *
THE accompanying illustration represents the artificial and natural way
of preserving food in an uninjured state. The right-hand figure is that
of an ordinary glass aquarium, such as was in general use until the
properties of air and water were better understood, and it still need
not be rejected. It is simply a vessel in which water is contained, so
that aquatic or marine animals may be able to live in it for some time.
There are infinite varieties of the “Fish-tank,” if we may so call it,
the chief of which is the “well,” which is so extensively used in
bringing fish to market.
Through the bottom of the boat projects a sort of box pierced with
holes, so that the water has free access and egress. The sides of the
box are so high that there is no fear of the water rising into the boat.
When fish are taken, they are thrown into the well, and there can live
until they are wanted for sale.
Also, as all know who are acquainted with river-banks or seashores,
fishermen have similar wells detached from the boats, and partly or
entirely sunk in the water. In them they keep their stock, and, when a
customer arrives, they simply draw the box ashore, so that the water
runs out, select what fish they choose, and replace the box in the
water.
* * * * *
NOW, the power of conveying fish to some distance without destroying
life has for countless ages been possessed by the Pelican, one of which
birds is shown in the accompanying illustration.
As every one knows, the chief peculiarity of this bird is the large and
very elastic membrane of the lower jaw. When not in use, it contracts by
its own elasticity, and the bill looks quite slender, as well as long.
But, when distended with water and fish, it presents the appearance
shown in the illustration.
Any one who wishes to see the exercise of this power can do so by
attending the Zoological Gardens, and visiting the Pelicans at
feeding-time, and an hour or two before it. They hardly seem to be the
same birds. Some years ago I made a series of sketches of the same
Pelican under different circumstances, and it is scarcely possible to
believe that they could be, as they are, truthful representations of the
same bird.
* * * * *
THE right-hand figure of the next illustration requires no comment, as
it simply represents the ordinary hen-coop.
As everybody is aware, the object of the coop is to keep the hen within
its bars, while the little chicks can run in and out as they choose, and
the coop is made so as to prevent the egress of the mother, while the
offspring find no difficulty in escaping.
* * * * *
NOW, in the world of insects we find an exactly analogous structure. As
is the case with many hymenopterous insects, there is in the nest of the
Termite, or White Ant, as it is popularly called, a single perfect
female, which is the mother of the nest. A similar arrangement occurs in
the common hive-bee, but there is a notable distinction between the
queen Bee and the queen Termite, the latter belonging to the
neuropterous order.
[Illustration: QUEEN TERMITE IN HER CELL.]
[Illustration: HEN IN HER COOP.]
The former is unconfined, and moves about from cell to cell, depositing
her eggs within them, and taking the greatest pains that they occupy
exactly their proper place within the cell. The latter never moves after
she has begun to deposit eggs, but remains motionless in the same spot,
and allows her subordinates to dispose of the eggs which she lays.
How this end is achieved will now be seen.
The reader is probably aware that the queen Termite attains to enormous
dimensions, her head, thorax, and legs retaining their normal size, but
the abdomen becoming several inches in length, and thick in proportion.
The legs are necessarily unable to move so vast a body, and in order
that so important a personage should not receive injury, a large oval
cell is built around her, from which she never moves for the rest of her
life. She has but one duty, namely, to lay eggs, and so is fed that she
may have strength to produce them. She is simply passive, and never even
sees her eggs, much less has care of her young.
All the care of guarding and nurturing the eggs and young falls upon the
worker Termites. These insects are quite small, about the size of our
common Wood-ant.
When they build the clay cell around their queen, they bore a number of
holes along the sides, which are just large enough to allow the workers
to pass freely, but which effectually exclude the soldier Termites, or
any foes larger than themselves.
Through these apertures streams of workers are continually passing--some
entering the cell to fetch the eggs, and others coming out with eggs
carried carefully in their jaws.
[Illustration: “WURBLES” OF ŒSTRUS.]
[Illustration: EGG-HATCHING MACHINE.]
Thus, as the reader will see, we have in Nature an exact analogy of Art,
the Termite queen being confined within her cell exactly as is the hen
within the coop.
* * * * *
BEING on the subject of eggs and egg-hatching, we will take another case
in which Art has acknowledgedly followed Nature.
We all know that eggs are developed into life by means of well-regulated
heat, and that with birds the general rule is, that the needful heat is
supplied by the parent bird, who sits upon them for a certain time,
until the young birds make their appearance in the world.
Under ordinary circumstances, the aid of the parent bird is quite
sufficient; but when the progress of civilisation requires that the eggs
of poultry should be hatched in numbers too great for the powers of the
parent bird, Man has been fain to imitate Nature, and to invent machines
whereby eggs can be hatched by artificial heat, regulated to the
temperature of the hen’s body.
Various as are these machines in detail, they are all alike in
principle, and the right-hand figure of the accompanying illustration
will give a fair idea of the method which is employed.
A box is fitted up with trays, on which the eggs are arranged. At the
bottom of the box there is the heat-producing apparatus, which can be
regulated at pleasure. The trays of eggs can be moved from one part of
the box to another, so as to insure the right amount of heat, and, if
this process be only carefully carried out, the young chicks emerge from
the eggs exactly as they would have done if the hen had sat upon them.
This machine is sometimes called the Artificial Mother, and it is worthy
of notice that it is no modern invention, the ancient Egyptians having
used it more than three thousand years ago.
* * * * *
WITH regard to Nature, it would have been simple enough to give one
illustration of a bird sitting on her eggs, but I have preferred to
select a different subject, as more relevant to the question of
artificial heat.
There is an insect to which we have had several occasions of reference,
namely, the Wurble-fly of the ox, scientifically known as _Œstrus
bovis_.
The eggs of this insect are deposited in the skin of the ox, and are
there hatched by the heat of the animal. In proportion as the larva
grows, it raises lumps upon the skin, these being practically the roofs
of the artificial home. There are several other species of the same
genus, all of which have their eggs hatched by the heat of the animals
on which they are placed. There are, for example, the common Bot-fly
(_Œstrus equi_), whose eggs are hatched in the interior of the horse,
and the Sheep-fly (_Œstrus ovis_), whose eggs are hatched in the head
of the sheep. The common Snake leaves her eggs to be hatched in the
artificial heat produced by decaying vegetable matter.
* * * * *
WE now come to the preservation of provisions.
In the first place, we have the well-known “cache” of Northern
America--_i.e._ a spot wherein provisions are hidden, and their locality
only marked by signs intelligible to those for whose use they are
intended. It is, perhaps, hardly necessary to mention that many
creatures--such as the dog, the squirrel, and most of the crow
tribe--are in the habit of concealing provisions for future use.
[Illustration: SPIDER-NESTS.]
[Illustration: EGGS OF LACE-WING FLY.]
[Illustration: SPIDER-NEST.]
[Illustration: PROVISIONS HUNG TO TREE BRANCH.]
In those parts of the world, however, where the rights of hunters are
acknowledged, any one who kills a deer, or other animal of chase, and is
not able to carry off the entire body, can preserve it for his own use.
He simply cuts it up in hunter fashion, and hangs the various portions
to branches of trees, where they are out of the reach of wild beasts.
Stores like these, such as are shown in the illustration, are always
respected, and no hunter would dream of helping himself to the game
which was killed and dressed by another.
Beasts of prey, however, cannot be expected to be so punctilious, and in
consequence the hunters hang their meat to branches which cannot be
reached.
* * * * *
IN Nature we find many similar examples, one or two of which are given
on the left hand of the illustration.
In the centre is seen a group of eggs of the Lace-wing Fly
(_Hemerobius_), so called on account of the delicate, lace-like
structure of its beautiful pale green wings.
When the female lays her eggs she always chooses a slight twig, and
upon it deposits a little drop of a slimy consistence. She then draws
out this drop into a thread, which hardens as it is brought into contact
with the air. At the extreme end of the thread she places an egg, which
is thus kept at some height above the ground, and defies the approach of
inimical insects. The eggs, as well as the stalks, are perfectly white,
and have so singular a resemblance to mosses, that for many years they
were actually classed and figured as such.
These egg-groups are plentiful enough, if the observer only knows where
to look for them. I have several of them in my collection, and have
found that nearly every one who sees them for the first time takes them
for mosses. I never myself saw the pretty insect lay its eggs, and for
the description am indebted to Mr. A. G. Butler, of the British Museum,
who has kept them and watched their habits.
The objects on either side of the Lace-wing Fly’s eggs are egg-groups of
certain spiders, suspended by threads from branches.
* * * * *
A STILL more remarkable instance of unconscious imitation may be found
in the two objects in the accompanying illustration. It is hardly
necessary to say that the right-hand figure represents a portion of the
arrangement by which a butcher hangs up his meat out of harm’s way until
it is wanted.
The hooks in question are simply formed into a double curve, like the
letter S, and can be slid along the horizontal bar without any danger of
falling.
Now, in the common Sloth we have an exact prototype of the butcher’s
hook. The Sloth passes the whole of its life in the remarkable attitude
which is shown in the illustration. It lives among the branches--not on
them, but under them--its claws being long and curved, just like a
butcher’s hook. I have often watched the animal traversing the branches,
and have been greatly struck with the accurately picturesque description
of the late Mr. Waterton, who was the first to discover the real
character of the Sloth.
It was he who found out that the previous ideas as to the Sloth’s mode
of life were utterly erroneous, and that, instead of being a sort of
bungle, the Sloth was as perfect in its way, and as well fitted for its
mode of life, as the lion or tiger. He discovered that the animal
always hung from the branches, as shown in the illustration. In fact, as
Sydney Smith remarked in his witty review of “Waterton’s Wanderings,”
the Sloth passes his whole life in suspense, “like a young clergyman
distantly related to a bishop.”
[Illustration: SLOTH.]
[Illustration: BUTCHERS’ HOOKS.]
* * * * *
THERE are many other creatures which afford similar examples, though
perhaps none are so striking as the Sloth.
For instance, there are the whole tribe of Bats, which, by means of the
curved claws attached to their hind-feet, can hang themselves head
downwards in the open air, and even swing in wind, without the least
fear of falling.
USEFUL ARTS.
CHAPTER VIII.
DOMESTIC COMFORT.
How to make Home comfortable.--The Bed in its various Forms.--The
Feather Bed of Man.--The Eider-duck and her Plumage.--The Rabbit
and her Down.--The Long-tailed Titmouse and her wonderful
Nest.--The Hammock of civilised Man and Savage.--The Sailor’s
Canvas Hammock.--The String Hammock of tropical America.--Nest of
the Pensile Oriole.--Silken Hammock of the Tiger-moth and other
Insects.--The Mat Bed.--Cocoa-nut Matting.--The Robber-crab and its
Bed.--Strength and Uses of the Cocoa-nut Fibre.--The Surgeon’s
“Cradle” and the Pupa of Tabanus.--The Art of Sewing and the
Tailor-bird.--Principle of the Umbrella and its Original
Use.--Natural Umbrella on the Rosemary.--Servants and Slaves, and
the Distinction between them.--The Use of Slaves in hot
Countries.--Slavery in the Insect World.--The Ants and their
Slaves.--Ornamental Gardening and Pleasure-grounds.--The Hanging
Gardens of Babylon.--The Bower-birds and their Pleasure-grounds.
We now come to a different branch of the same subject, namely, the means
by which our dwellings are rendered comfortable.
After having procured a dwelling which can withstand the elements, we
next look for a bed on which to repose, and which will ease the limbs
and brain, wearied by the toils of the day.
Allusion has already been made to the ordinary feather bed and its
multitudinous natural springs. We now have to see how the various kinds
of beds are anticipated in Nature, and will begin with the feather bed.
As to our own beds, nothing need be said about objects so familiar,
although, in order to preserve the parallelism, it is necessary to
introduce an illustration on the right hand of the page.
On the left hand are shown two examples of natural feather beds,
selected from many others on account of the exact parallels which they
afford.
We all know the wonderful warmth and lightness of the Eider-down
mattress or quilt, though there are comparatively few who know how the
Eider-down is procured.
In common with many other creatures, the Eider-duck forms a bed for her
young by plucking the down from her own body. Rabbits do exactly the
same thing, as all boys know who have kept them, the only difference
being that fur is substituted for feathers. So do many insects,
stripping themselves of their own downy covering, and employing it for
the comfort of their offspring.
[Illustration: LONG-TAILED TITMOUSE.]
[Illustration: EIDER-DUCK.]
[Illustration: FEATHER BED.]
The lower figure on the left hand represents the Eider-duck in the act
of plucking the far-famed down from her breast in order to make a soft
and warm couch for her young, and the amount of feathers which she will
devote to this purpose is simply astonishing. Their weight is
insignificant, but their bulk is wonderful.
Above the Eider-duck is shown the nest of the common Long-tailed
Titmouse. It is the most perfect nest that is constructed by any British
bird. Its shape exactly resembles that of an egg, and it has but one
small aperture, as is shown in the illustration.
The Titmouse lays a vast number of eggs, and almost fills the nest with
soft downy feathers, on which they can rest. If the finger be introduced
into the nest through the aperture, the tiny eggs can be felt reposing
in their natural feather-bed. In this case, however, the bird does not
denude herself of feathers, but has a way of picking them up wherever
she can find them.
* * * * *
NOW we will take another form of bed, namely, the Hammock, which is used
in many parts of the world.
Putting aside the well-known hammock as used on board our ships, we will
take the same kind of bed as used among the natives of tropical America.
In that wonderful part of the world, where water and vegetation reign
supreme, an aërial couch of some kind is absolutely needful, and is
supplied by the singularly ingenious hammocks which are constructed by
the natives. They are made of a fine, but marvellously strong fibre,
procured from the aloe plant by the simple process of soaking the long
leaves in water, and dashing them against a stone. The soft green parts
are eaten away, and the tough fibres remain in all their strength.
From these fibres are woven the strings of which the Hammocks are made.
I possess four of the Hammocks, all made on different lines, but all
based on the same principle. In some the strings are laid parallel to
each other, and connected by transverse strings at regular intervals,
but in the best specimens they are interlaced diagonally into a sort of
loose network without knots, so that it yields in every direction to the
outlines of the body.
It is one of the most comfortable couches ever invented, especially when
it is of considerable size. I have one specimen which, even in its
curved state, extends completely across a tolerably sized room. I never
use it because it is so comfortable that the temptation to lie in it is
almost too strong to be resisted.
* * * * *
AS to Hammocks in Nature, they are almost too many to be computed.
So we will first take the nest of the Pensile Oriole, which is shown in
the illustration, and which is an admirable example of the Hammock,
being woven from long vegetable fibres intertwisted very much like the
strings of the South American Hammock. And as if to increase the
resemblance, the bird, whenever it can do so, will carry off hanks of
cotton, linen, thread, or pieces of string, and weave them into its
nest.
I have one of these nests, and, directly I saw it, was struck with its
exact similitude to the Hammock of human manufacture.
[Illustration: NEST OF PENSILE ORIOLE.]
[Illustration: HAMMOCK.]
There are many other birds in various parts of the world especially in
Australia, which make their nests on exactly the same principle, though
in slightly varied forms.
Also, in the insect world, there are innumerable examples of the natural
Hammock, the most common of which is that made by the caterpillars of
the Tiger-moth, and in which it slings itself while undergoing its
changes from the chrysalis to the perfect state.
It is made of silken threads, interwoven so slightly that the chrysalis
can be seen through them, and so exactly like the Hammock of the South
American Indian that if a drawing were made and enlarged, one might
easily be taken for the other.
* * * * *
NOW we come to the Mat Bed, which is so much used in the warmer parts of
the world, where the earth is dry, and the air so warm that nothing is
required but the slightest possible protection from the soil.
In inland places, such as Southern Africa, the bed is made of long
grass-stems laid side by side, and sewn together with a sort of twine.
One of these beds in my collection is some three feet wide by seven feet
long, and can be rolled up into a cylinder so compact and light that
even a child could carry it.
[Illustration: ROBBER-CRAB.]
[Illustration: COCOA-NUT MAT.]
Of course, when the Kafirs are on a journey, the women have to carry the
beds, together with the heavy wooden pillows and other necessaries, the
men carrying nothing but their weapons. I have a pair of figures made by
a native artist, representing a Kafir man and woman on a journey, the
woman staggering under her heavy burdens, the bed being included, and
the man stepping lightly along, with nothing but his spears and
knobkerries.
* * * * *
ON the sea-coasts, however, where the cocoa-nut palm grows, the fibre of
the husk is the principal material for bedding. These fibres lie so
parallel to each other on the surface of the cocoa-nut, that they are
easily stripped off, fastened together, and formed into mats of any
shape or thickness. One of these mats is shown on the right hand of the
illustration, and the reader will see how simple is its manufacture.
Owing to the ease with which it is made into a fabric, the cocoa-nut
fibre was in great use as armour before the bullet set all armour at
defiance. It will be remembered that when Captain Cook was murdered, he
committed the mistake of firing a charge of small shot instead of a
bullet, and the fact that the cocoa-nut mat carried by the man at whom
he fired resisted the shot, encouraged the natives to attack and murder
him.
* * * * *
EVEN the cocoa-nut mat has its precursor in Nature.
There is a certain Crab inhabiting the cocoa-nut bearing parts of the
world, which not only makes itself a bed from the fibre, but supplies it
to mankind.
This wonderful Crab has the power of ascending the cocoa-nut palms,
which is beyond the power of any man except a trained gymnast. It picks
out the ripest fruits, and with its powerful claws tears off the fibre
before breaking the shell and devouring the kernel, as is shown in the
left-hand figure of the illustration.
After eating the kernel, which is at that time a soft, creamy substance,
quite unlike the hard, indigestible material which we in England know by
the name of cocoa-nut, the Crab carries off the external fibres into its
den, and there makes its bed of them. So great, indeed, is the amount of
cocoa-nut fibre thus collected that the natives are accustomed to save
themselves the trouble of climbing the trees, and merely search for the
holes in which these Crabs have made their nests, knowing the amount of
ready-gathered cocoa-nut fibre that is always to be found in them.
* * * * *
ANOTHER modification of the bed needs a short notice, especially as I
have practical and sad experience on the subject.
[Illustration: PUPA OF TABANUS.]
[Illustration: SURGICAL CRADLE.]
It is technically named the “cradle,” and is used to keep the bedclothes
from pressing on a damaged limb.
When a mere lad I contrived, at cricket, to dislocate the right ankle,
and break the bone. An ignorant surgeon refused my request for a cradle,
and absolutely tied the cover of a book to the sole of the foot. Of
course this appliance was worse than useless. It acted as a lever,
allowing the clothes to turn the foot round, and to the present day the
right foot has never recovered its faculties. Had the simple “cradle”
been used--_i.e._ a few sticks bent into an arch-like shape, and tied
together, so as to keep the clothes from even touching the foot--all
would have been right.
On the right hand of the illustration is shown the surgical cradle, as a
defence to a damaged leg. On the left is shown the curious natural
cradle of the Gad-fly while undergoing its change into the perfect
state. It is quite hard and rounded, being formed from the skin of the
larva, and allows the pupa to lie within it, protected from any ordinary
pressure.
* * * * *
ANOTHER point now comes before us.
We cannot well have our bedclothes--indeed, any kind of clothes--without
the use of needles and thread. The simplest form of sewing is that which
is adopted in many parts of the world, namely, of boring holes and
pushing a thread through them, no eye being required in the needle. In
this way the Kafirs of Southern Africa and the Esquimaux of the Polar
regions make their beautiful garments of skins. I have for many years
had in constant use two South African cloaks, or karosses, and one made
by the natives of Vancouver’s Island, and they are now as good as they
were when they were first given to me. Naturally, such a mode of sewing
consumes much time, but, as time is not of the least value to these
native furriers, no harm is done, and the junctions of the different
skins is absolutely perfect. Even where holes have been made in the
skin, the native furrier has supplied their places with circular pieces
so neatly inserted, that on the outside not a trace of the junction is
visible, and even the very set of the hairs is preserved.
Our very modern needles, with their eyes which carry the thread, are but
a modification of the original plan of boring holes, and pushing the
thread through them.
* * * * *
NATURE has a singular parallel in the case of the Tailor-bird, which
sews leaves together by their edges, and makes its nest inside them. It
acts exactly like one of our own shoemakers, using its slender and
sharply pointed beak in lieu of the awl, and employing a slight but
strong vegetable fibre in place of the “waxed end” of the shoemaker, or
the sinew-thread of the Kafir.
In the illustration an ordinary needle and thread are seen on the
right-hand side, and on the left are two nests of the Tailor-bird, taken
from specimens in the British Museum.
[Illustration: TAILOR-BIRDS AND NESTS.]
[Illustration: SEWING CLOTH.]
The mode of sewing is strangely like that which is employed by the
uncivilised furriers who have been described, and much superior to that
which is seen in many other parts of the world. For example, I have a
West African quiver made of hide sewn together with stitches infinitely
more clumsy than those of the Tailor-bird.
The reader will also remark that I might have placed this singular nest
in the category of beds, on account of the soft and warm lining on which
the young repose. I have, however, thought that it more properly belongs
to the present division of the subject.
* * * * *
SOMETIMES we require a temporary as well as a permanent shelter from the
elements, and procure it by means of the Umbrella.
In many countries, especially those where the climate is hot, the
Umbrella is almost exclusively used, as, indeed, its name denotes, to
preserve its owner from the direct sunbeams, and is, in fact, the
“parasol” of our European ladies. It also is a mark of dignity, the
amount and quality of its decorations indicating rank, even though the
man who sits under its shade is clothed in a modest cotton cloth wrapped
round his waist.
For the purpose of shielding the bearer from the sun the Umbrella was
first introduced, and the introducer incurred the obloquy usual in such
cases. Now, however, the Umbrella has by common consent become a
defence against rain and snow, the male sex leaving the parasol to the
gentler half of creation, and submitting themselves to the chance of a
sunstroke.
* * * * *
WE all know the ingenious Umbrellas of Africa, China, Japan, Siam, &c.;
but there are few persons who know that a common magnifying-glass will
disclose thousands of beautifully perfect umbrellas on the leaf of the
Rosemary.
[Illustration: HAIRS OF ROSEMARY.]
[Illustration: UMBRELLA.]
Pinch the Rosemary-leaf between the fingers, and a strong and peculiar
perfume is evolved, just as when the peel of the orange is squeezed. The
reason is the same in both cases, namely, the presence of multitudes of
spherical vessels which contain their essential oil, secreted by the
plant.
In the orange they are sunk below the surface of the skin, and are
protected by it; but in the Rosemary they stand on slight footstalks, as
shown in the illustration.
Being very delicate, and liable to be broken at the least touch, they
are protected by a series of curiously formed hairs, which extend over
them exactly as would an umbrella, and defend them from the elements.
The surface of a Rosemary-leaf affords a singularly beautiful sight,
even with a common magnifying-glass, the tiny perfume-globes gleaming
like little pearls in the broken lights that shine through the
umbrella-like hairs.
* * * * *
NOW we come to another part of domestic life, namely, Servants.
There is a diversity of ideas on this subject, as we know by the
various discussions respecting “lady-helps” and “gentlemen-helps,” which
bid fair to initiate a revolution in domestic life. Servants are
sometimes called the greatest plagues in life, but it is difficult to
see what could be done without them.
Then there is the complaint that servants are not what they used to
be--the faithful retainers of the household, and considering themselves
members of it. Perhaps not, but I have had experience of several
faithful retainers, and invariably found them to be unmitigated tyrants,
assuming power, repudiating responsibility, and being practically the
master or mistress of the household.
Then we come to the great question of slavery in its various bearings.
Putting aside the now acknowledged diversity of races, and the
well-known fact that the negro in a state of slavery to a European is
infinitely better off than he would have been in his own country, where
there is no law but that of might, we must entertain the question of
enforced servitude, i.e. where the servants have no choice either in
entering or leaving their situations.
It is, of course, opposed, and rightly, to our modern English ideas that
a slave, under such a name, should exist on British ground. Yet there
are thousands of Englishmen who are more wholly enslaved than was any
negro in the worst times of slavery. The chains may not be of visible
iron, nor the whips of tangible thongs, but they are, perhaps, all the
more galling and biting.
* * * * *
SOME of my readers may be aware that slavery exists in the insect world,
and probably existed long before man came on earth.
There are many species of Ants which are absolutely incapable of
managing their own nests or rearing their own young, and which, in
consequence, impress into their service the workers of other species of
Ant, and hand over to them the entire labour of the establishment. They
can fight, and they can establish fresh colonies, but they cannot build
nests, nor nurse their young, and so they impress into their service
those Ants whose instinct teaches them to do both.
Periodically the master Ants, if we may so call them, set off on a
slave-hunting expedition. They find out the nest of the special Ant
whose aid they need, penetrate into it, and bear off the pupæ, or “ants’
eggs,” as they are popularly called. These are carried to their new
home, and are speedily hatched. They know no other home, and, led by
instinct, set to work as industriously as if they had never been
removed.
[Illustration: SLAVE-CAPTURING ANTS.]
[Illustration: AFRICAN SLAVE-GANG.]
Those who have watched their habits are unanimous in declaring that they
seem perfectly happy and contented. No compulsion is used towards them,
and they work because told to do so by their own instinct. Work they
must, and it does not in the least matter to them for whom the work is
done.
* * * * *
ANOTHER branch of this subject is shown in the accompanying
illustration, namely, the pleasure garden or playground.
This is, as we all know, a token of high civilisation, and even in the
ancient times the hanging gardens of Babylon were reckoned as the
greatest wonders of that great city, the then mistress of the world.
No savage ever dreamed of such a thing as a pleasure garden, nor could
appreciate it if he saw it. Yet there are birds which far surpass the
savage in this respect, and which build recreation grounds for the sole
purpose of amusement.
These are the well-known Bower-birds of Australia, which I sincerely
hope may not be extirpated by the white man, as has been the case with
so many creatures, including the aborigines of Tasmania themselves.
The Bower-birds, which are distantly related to our thrush and
blackbird, but are about as large as jackdaws, have a curious habit of
building arched bowers quite independent of their nests.
The shape of one of these bowers is shown in the accompanying
illustration.
The bird first weaves a sort of platform of flexible sticks, and then
fastens into them a number of other sticks, so set that they form a sort
of arched gallery. Through this gallery the birds love to run, and they
invariably decorate the ends with anything pretty that they can pick up,
such as feathers, coloured stones, shells, ornaments, and the like. So
well is this proclivity known, that whenever any one who is living in
the Bush loses any small piece of property, such as a pencil-case or
watch-key, or even a tobacco-pipe, he always goes to the Bower-bird’s
pleasure garden, and mostly discovers the lost property.
[Illustration: PLAYGROUND OF BOWER-BIRD.]
[Illustration: GARDEN BOWER.]
At the Zoological Gardens these Bower-birds have long lived, and it is a
most interesting sight to watch them weaving their platforms, raising
the bowers over them, and then keep running in at one end and out at the
other, like children at play, and with their burnished plumage gleaming
in the sunbeams.
The right-hand figure simply depicts a modern pleasure garden, and needs
no description.
USEFUL ARTS.
CHAPTER IX.
ARTIFICIAL WARMTH.--RING AND STAPLE.--THE FAN.
Various Modes of warming Houses.--The Fire of the American Indian
and the Kafir.--The Oil-lamp of the Esquimaux.--The open Fireplace
and Chimney Stoves.--The laminated Stove and its Powers.--Gills of
the Lobster, Crab, and various Fishes.--Mode in which the Gills
act.--Why Fishes lie with their Heads against the Stream.--Drowning
a Fish.--The Ring and Staple, and their various Uses.--Head-bones
of the Fishing-frog or Angler-fish.--The Fan and its
Modifications.--Japanese and Chinese Fans.--The Feather Fan.--The
Palm-leaf.--Indian Fans.--The Hive Bee and its Wings.--Fans of the
Essequibo and South Sea Islanders.--The Fan Fire-guard.--Antennæ of
the Cockchafer.--Burial.--Various Modes of disposing of the
Dead.--Ordinary Habits of dying Animals.--Dead Insects.--The
Funeral-ant and its wonderful Habits.
ARTIFICIAL WARMTH.
Passing from the direct to the indirect comforts of a household, we will
take Artificial Warmth.
The savage, as a matter of necessity, makes a fire in the middle of his
hut, and lets the smoke have its own way. Sometimes, as is the case with
the North American Indians, the top of the conical hut is open, and the
whole edifice is a single chimney of large dimensions, something like
the “chimney-corner” of past days, which only survives in such places as
the New Forest.
Then there are the various Kafir tribes of Southern Africa. They have no
aperture in their huts except the tiny doorway, which can only be
entered on hands and knees. But they must have their fire. No argument
can persuade them that they had better make their fire and cook their
food outside the hut. So the wood-smoke fills the hut, coats it with a
lining of soot, and gets out as it can through the sticks and withes of
which the simple edifice is built.
As a contrast, we have the oil-lamp of Esquimaux-land, where there is no
provision for ventilation, where the snow-houses are tightly closed and
crammed with inhabitants, and where no one seems to need fresh air.
The next step in civilisation is to construct a tube for the purpose of
carrying off the smoke, such as we know by the name of chimney or flue,
and to place the fire within it. We English people have an ingrained
love for the open fireplace, and though it really is an expensive
arrangement, it is worth the cost. Granting that it carries much of the
heat into the chimney instead of throwing it into the room, it has at
least the advantage of acting as a ventilator, of ejecting air which has
been rendered poisonous by respiration, and drawing a fresh supply from
the outer atmosphere.
In some parts of the world, especially in Germany and the United States,
the place of the open fire is taken by closed stoves, without any
ventilation whatever, much to the discomfiture of ordinary Englishmen.
Still, there are buildings, such as public halls and places of worship,
in which open fireplaces are wholly impracticable, and where it is,
therefore, necessary to make use of the stove.
It need hardly be said that in such cases the chief object is to procure
the greatest amount of heat with the least expenditure of fuel, and that
object seems to be best attained by the Laminated Stove shown on the
right hand of the illustration.
[Illustration: GILLS OF SHARK.]
[Illustration: GILLS OF TROUT.]
[Illustration: STOVE.]
In this stove, the outer surface, instead of being plain, is divided
into a number of perpendicular plates, which are heated by the
contained fire, and expose a very large surface of hot metal to the air.
Thus the heat, instead of being wasted by being drawn through the flue
or chimney, is thrown into the room, and keeps up a perpetual supply of
warm air.
* * * * *
THAT the invention of this stove is an ingenious one nobody can deny.
But Nature has been long in advance of Art in the way of exposing as
large a surface as possible with the least expenditure of space.
Very familiar examples of this structure may be found in the many
creatures which inhabit the waters and breathe by means of gills, which
extract the oxygen of the water.
Take, for example, a Lobster or a Crab, open it, and look at the white,
pointed, uneatable objects which are popularly called “ladies’ fingers.”
These are the gills, or breathing apparatus, and their structure is
really wonderful. They are composed of innumerable laminæ, or very thin
plates, covered with an exceedingly fine membrane, and placed closely
side by side, but with sufficient distance between them to allow the
water to percolate the whole structure.
With the aid of an ordinary pocket lens the observer may make out a most
wonderful system of blood-vessels, which permeate every one of the
myriad laminæ, and which extract the life-giving oxygen from the water
as it passes between them.
Then, to pass to animals of a higher order, take the gills of fishes.
Any fish will do, provided that it be fresh, and, if it can be examined
immediately after death, so much the better. Taking things reciprocally,
the gills of the fish and the laminæ of the stove, are identical in
principle, namely, the exposure of much surface with little loss of
space.
If possible, the observer should inject the blood-vessels of the gills
with the conventional crimson and blue wax, showing the currents of the
arterial and venous blood. Each lamina forms a most wondrous object, and
may be gazed upon for weeks with increasing admiration.
Every one who has watched the habits of fishes must have noticed that in
running waters they always have their heads against the stream, and do
not greatly care about shifting their positions.
In still waters, especially such as those of the ordinary glass
aquaria, the fish are perpetually on the move, whereas in such a river
as the Dove of Derbyshire, and even the Darenth of Kent, large trout may
be seen almost motionless, but invariably with their heads directed up
the stream.
The reason is evident enough. As long as the fish lies with its head up
the stream the water flows through its gills, and enables it to breathe.
Were the passage of the water stopped, the fish would be drowned.
Consequently, all good anglers, when they hook a fish which is worth
taking, keep its head down the stream, prevent the water from washing
over its gills, and consequently render it so weak by deprivation of
oxygen, that it becomes an easy prey, and is rendered subservient to a
line of a single hair. Let the fish breathe, and a single struggle would
smash a line of treble the strength. But keep it from breathing by
directing its head down the stream, and it rapidly loses all strength,
and can be directed into the landing-net, or brought within the scope of
the gaff, without a chance of escape.
* * * * *
I NEED hardly remark that on the right-hand side of the illustration is
shown a Laminated Stove, and that on the left are drawings of the gills
of the Shark tribe and the common Trout. If the reader would really like
to look into the subject for himself, I should suggest the purchase of a
cod’s head and shoulders and a lobster. The breathing apparatus can be
removed from each for examination, and the remainder will serve as a
first course for dinner.
RING AND STAPLE.
Humble, and apparently insignificant, as the principle of the Ring and
Staple may be, we owe no small amount of our domestic comfort to it. It
meets us in all kinds of ways, in the hinges of our boxes, in the
padlocks of our doors, in the innside fastenings for our horses, in the
seaside fastenings for ships’ cables, and in a thousand other ways too
many to enumerate.
* * * * *
ON the right-hand side of the next illustration is shown the Ring and
Staple as used for the purpose of mooring ships and boats, it being
absolutely necessary that the machinery, simple as it is, must be
capable of working in any direction, and with some latitude as to the
extent.
[Illustration: HEAD-BONES OF ANGLER-FISH.]
[Illustration: STAPLE AND RING.]
On the left hand are shown two of the wonderful bones which are found in
the head of the Fishing-frog or Angler-fish (_Lophius_), and which serve
as decoys, by means of which the smaller fish are entrapped into the
vast jaws of the Angler-fish.
It is clearly necessary that these singular appendages should be capable
of movement in every direction, and this object is attained by the
structure which is here shown, and which is almost equal to the
ball-and-socket joint for its freedom of movement. It will even allow of
partial rotation, so as to cause the little strip of skin at its end to
assume the aspect of a living worm, and entice the smaller fish into the
jaws of the dread trap that lies open before them.
A figure of this fish may be seen on page 92.
THE FAN.
Except in permanently cold countries, a Fan of some kind seems to be an
absolute necessity. Sometimes, as in the greater part of Europe, it is
used only by the softer sex. The harder sex would often be only too glad
to use it if they dared, and the same observation is equally true with
regard to the parasol.
But, in such lands as Japan and China, the Fan is an absolute necessity
of existence. Men, women, and children alike carry their Fan, and almost
perpetually use it. I remember, when the troupe of Japanese acrobats
were in England, that one of them exhibited the national use of the Fan
in an excessively ludicrous manner.
One of his comrades ascended to the roof of a lofty building, hung by
his legs to one of the rafters, and held in his hands a bamboo pole
which was twenty feet long. Another Japanese also ascended, climbed over
his comrade, and settled on the bamboo pole, to which he clung only by
the clasp of his bare feet. Suddenly he slipped down the pole, stopped
himself when within a few inches of the end, squatted there with perfect
unconcern, though at least forty feet from the ground, took his fan from
the back of his neck, and fanned himself while gravely surveying the
startled audience.
[Illustration: PALM-LEAF.]
[Illustration: JAPANESE HAND-SCREEN.]
Perhaps some of my readers may remember Chang, the Chinese giant, who,
by the way, in private life was a polished gentleman. He was never
without his fan, always keeping it fluttering gently with an ease only
to be acquired by a lifelong practice, and I really think that if he had
been deprived of it he would have been seriously ill. How he slept
without it is a wonder, for in his own house the fan was incessantly in
motion, and was worked with apparent unconsciousness on his part.
I have often wished that in our country the ladies would manage their
fans in the same quiet way when they are in a church or a concert-room,
for the perpetual rattle of the joints is enough to distract any
preacher or conductor, and very often does so.
As to the shape of the Fan, it varies greatly according to the country,
but it may almost invariably be traced to some familiar object.
There is, for example, the common Japanese Fan or Screen, which is
avowedly made on the model of the Palm-leaf, the ribs of the leaf being
represented by split portions of a bamboo stem. The right-hand figure in
the preceding illustration is taken from one of the common sixpenny
Japanese fans that may be seen in many shop-windows.
There are exactly sixty ribs in the fan, all produced by splitting the
bamboo into strips, kept in their place by a slight rod of the same
material, and covered with two pieces of thin printed paper. Seeing that
the original cost cannot be more than a penny, it is wonderful how such
articles can be produced, and give a living to the makers.
The reader will observe that the shape of the Japanese Fan is almost
exactly that of the Palm-leaf, with the exception of the jagged edges,
and a better pattern could not be found. Then there are many Indian Fans
framed on the same model, but which revolve on their handles, and are
swung slowly round and round by the servants before the guests, and thus
become miniature punkahs.
Here, again, we may find a parallel in Nature. The common hive bee
ventilates its dwelling by using its wings in lieu of fans. When the
hive is really in want of fresh air, the bees set to work, and wave
their wings backwards and forwards for a considerable time, so that they
necessarily expel the foul air from the interior of the hive, and create
a partial vacuum, which can only be filled by fresh air from without.
Fans of very similar shape are in use among the South Sea Islanders and
the inhabitants of the Essequibo district. They are often used as
bellows when a fire has to be raised, but their primary object is to be
employed as fans.
* * * * *
NEXT we come to those fans which are made of flattened sticks, which
move on a pivot. This is, indeed, the ordinary form of the fan at the
present day, the sticks being sometimes wide enough to constitute the
entire fan, but mostly being connected with a sort of lining made with
silk, paper, or feathers. Such fans as these can be moved on their
pivots, so as to occupy a comparatively small space; and the same can
be said of the modern fender-guards, which can be folded up when the
room is unoccupied, and which form an effectual protection against the
danger of ladies’ dresses coming in contact with the fire.
Examples of such a screen, and two fans, are given on the right hand of
the accompanying illustration.
[Illustration: ANTENNA OF COCKCHAFER.]
[Illustration:
IVORY FAN. FEATHER FAN.
FIRE-GUARD.]
On the left hand is shown one of the natural objects from which the
fans, &c., might well have derived their origin. It is one of the
antennæ--or horns, as they are popularly called--of the common
Cockchafer. The end of this antenna is composed of a number of flat
plates, which work on a pivot exactly like the sticks of a fan, and,
like those sticks, can be folded into a wonderfully small compass, or
opened out into a fan-like shape.
BURIAL.
Last scene of all.
I do not think that it matters very much to one who has “shuffled off
this mortal coil” what becomes of the coil in which he had been
imprisoned. Whether the abandoned body be buried in the earth, or sunk
in the sea, or devoured by wild beasts, or consumed by fire, signifies
nothing to him, though it may signify much to his surviving friends.
As a rule, the animals, of whatever kind they may be, contrive to
dispose of their mortal remains in some mysterious manner, so that not
a vestige of them is to be found. Take, for example, the domestic cat,
and see how few bodies are found of cats which have died natural deaths.
For instance, there was my own cat “Pret,” who lost his life from the
bites of rats. He was blind, and so lamed that he could scarcely crawl.
Yet, on the day of his death, he three times escaped from his
comfortable bed in front of the fire, dragged himself through a hedge,
down a steep bank, across a road, up another bank, through a crevice in
a park fence, and curled himself up to die under a blackberry-bush.
[Illustration: BURYING-ANTS.]
[Illustration: SAVAGE FUNERAL.]
Perhaps it was mistaken kindness on my part, and I should have acted
better if I had left him to die in peace. But, though I carried him back
three times, and though he was quite unable to see, he contrived to slip
out of the house, and to find the same spot for his last resting-place
on this earth.
I have heard that some cats have been known to bury their young, and Dr.
J. Brown tells a most touching story of a dog that committed her dead
puppy to the river.
But as to Insects, until a few years ago, no one ever dreamed that the
principle of burial could be found among them. What millions of insects
die in every year, and how seldom is a dead insect found! Flies, gnats,
and the smaller insects might escape observation, but the large moths,
butterflies, beetles, dragon-flies, &c., are scarcely ever found dead.
In my own neighbourhood, for example, the Stag-beetle, nearly the
largest and most conspicuous of British insects, swarms to an almost
unpleasant degree, especially in the summer evenings.
Yet I have never found a dead Stag-beetle that had not been killed by
violence. What becomes of the bodies of the countless millions of
creatures that annually pass into their other world is a problem which
at present no one seems to be able to solve.
* * * * *
STILL, there are instances where even insects are known to bury their
dead, and I scarcely need say that they are to be found among the Ants.
The story is a very curious one, and is narrated at length in the
_Journal of the Linnæan Society_, vol. v. p. 217.
It happened that a lady found that her little boy was being stung by
ants, and she at once killed them and threw their dead bodies away.
After some time a number of ants came out of their nest, formed a
procession as regularly organized as that of any undertaker’s funeral,
dug graves for each dead ant, laid the body in it, and covered it up
again with earth.
They carried their organization to such an extent that they even had
relays of bearers. But the strangest part of the story is that several
worker ants would not assist in the funereal ceremonies. The soldiers at
once set on them, killed them, and tumbled them all promiscuously into a
common grave.
Such scenes were repeatedly witnessed by the lady, a Mrs. Hutton, who
wrote the account while she was living in New South Wales.
USEFUL ARTS.
CHAPTER X.
WATER, AND MEANS OF PROCURING IT.
The Necessity of Water to Man.--Composition of the Human
Body.--Natural and Artificial Distillation.--The Traveller’s
Tree.--Pitcher-plants and Monkey-pots.--Stomach of the Camel, and
its Analogy to the Honey-comb.--Dewdrops.--Use of the Still at
Sea.--Perspiration and its cooling Properties.--The Turkish
Bath.--Perfume and Ether Spray.--Condenser of the Low-pressure
Steam-engine.--The Dry and Wet Bulb Thermometer.--Ice produced in a
red-hot Vessel.--Power of Water.--How Fountains are made.--Modern
System of Hydrants.--Hydraulic Mining.--The Victoria and Niagara
Falls.--Artesian Wells.--The Norton Tube, &c., in Abyssinia.--The
Water-ram and Spout-hole.
IT has often been remarked that man can live a comparatively long time
without solid food, providing that he can only obtain water, of which
the chief bulk of the human body is made. Dying by thirst is a horribly
painful death, but, according to Mr. Mills, the ill-fated Australian
traveller, “starvation on nardoo (an innutritious plant) is by no means
unpleasant, but from the weakness one feels, and the utter inability to
move one’s self.”
Those who have been shipwrecked, and unable to obtain fresh water, have
always found that the tortures of thirst were infinitely harder to
endure than those of hunger; and the reader will probably remember that
those who perished in the Black Hole of Calcutta owed their deaths
chiefly to thirst, their bodies being exhausted of moisture by the heat
of the room, and no fresh supply attainable.
Civilisation especially shows itself in the way in which water is
brought within the reach of every one, even in the most crowded of
cities. The reader may probably call to mind the wonderful aqueducts of
ancient Rome, the gigantic remains of which still exist. Then, as to
our own country, we are all practically acquainted with some water
company, by which the water, more or less purified, is brought into our
houses, and can be obtained by the mere turning of a tap.
Yet all this ingenuity is but a following of natural prototypes, as will
presently be seen; and even the familiar Water-tank, as shown at the
right hand of the illustration, has been anticipated by Nature.
* * * * *
ON the left hand of the illustration there are three examples of natural
water-tanks, two belonging to the vegetable, and one to the animal
kingdom.
[Illustration:
TRAVELLER’S TREE.
STOMACH OF CAMEL.
PITCHER-PLANT.
CISTERN.]
That on the extreme left, with a number of radiations, represents a
portion of a Madagascar palm, popularly called the Traveller’s Tree.
Having very large leaves, arranged in the manner there shown, the
Traveller’s Tree condenses the nightly dews, and allows them to trickle
down into the hollows of the leaf-stems.
There the water remains, out of the reach of sunbeams or wind, and if a
traveller happens to be thirsty, all he has to do is to pierce the base
of one of these gigantic leaves, and out rushes a stream of the purest
water, as is shown in the illustration.
* * * * *
NEXT to the Traveller’s Tree is shown one of those extraordinary
vegetables called Pitcher-plants, from the strange conformation of the
leaves. They inhabit Borneo, Siam, and other hot countries. In these
remarkable plants some of the leaves are developed into suitable
pitchers, with hinged lids, exactly like our hot-water jugs. They serve,
however, a different office, and contain cold water which the plant has
distilled from the dew.
As the monkeys are in the habit of resorting to these plants when
thirsty, they are sometimes called Monkey-pots. There is an admirable
account of the Pitcher-plants and their development in the _Transactions
of the Linnæan Society_, vol. xxii. part iv. The scientific name of
those plants is Nepenthes.
* * * * *
BELOW the vegetable comes a rather celebrated animal cistern, namely, a
portion of one of the stomachs of a Camel.
It exactly corresponds with that part of an ox which butchers call
“honey-comb tripe,” and consists of a multitude of cells, which can be
closed or opened at will. When the camel takes in its provision of
water, it can treat this portion of the stomach much as the hive bee
treats the honey-bag, and fill its cells with water.
By degrees, when it finds the necessity for moisture, it can squeeze the
water out of these receptacles into the digestive portion of the
interior, and so can sustain life for a wonderfully long time under
conditions which would kill any other animal. I may remark, by the way,
that the amount which a camel can drink, and the length of time through
which it can endure its desert life, have been much exaggerated. There
is another point to be considered, namely, the curious resemblance
between these cells and the honey-comb of the hive bee. Every one knows
that honey, no matter how tightly closed, will crystallize and lose its
best qualities if kept in jars, whereas if it be allowed to remain in
the waxen comb, where it is divided into very small portions, it will
remain good for years.
It is just the same with the cells of the camel’s stomach, they being
able to preserve water in a pure state by distributing it among a number
of small cells, which can be opened or closed at will.
Then we come to the various means of obtaining water.
Reference has already been made to the Filter, by which foul water can
be made pure for human consumption, and we will therefore pass to
another mode of obtaining pure water, namely, the Still.
In former days, if there were a failure of the supply of fresh water on
board ship, the whole of the occupants must necessarily perish. Now,
however, no such danger exists, as every well-furnished ship carries at
least one Still, by means of which the sea-water can be made to abandon
its salt, and to give out nothing but pure water fit for drinking.
Even in cases where no regular Still has been on board, an extemporised
Still has been made from a kettle, a gun barrel, or piece of lead
piping, or anything of a similar nature.
[Illustration: DEWDROPS.]
[Illustration: STILL.]
The principle of the Still is simple enough, and is shown by the
diagram, rather than drawing, on the right hand of the illustration.
There is a vessel in which liquid is boiled. From the upper part of it
rises a tube through which the steam must pass as it is generated. The
tube in question is generally of considerable length, and is coiled
inside a vessel filled with cold water, rendered colder by ice, if
possible.
As the steam passes through the cold tube condensation takes place, and
it becomes liquid again, but deprived of its heavier particles, so that
if sea-water be placed in the still, the salt is left in the vessel, and
nothing but pure water passes through the tube. In dissecting-rooms a
small still is almost invariably kept. Many preparations are of such a
nature that the spirit in which they are placed becomes discoloured, and
has to be repeatedly changed. Now, even methylated spirit is an
expensive article, and therefore, instead of being thrown away, the
discoloured spirit is placed in the still, and reproduced in a clean and
transparent state.
Nature affords innumerable examples of distillation, the chief of which
are the Dewdrops which have already been mentioned. During the daytime
the air is full of moisture drawn by the sunbeams from ocean. We cannot
see it, but it is there, and when the chill of night cools the various
trees, herbage, and other such objects, the aërial moisture is condensed
upon them, which is then known by the name of Dew.
On the left hand of the illustration are shown the tiny Dewdrops as
hanging on the slight threads of a spider’s web, and collected in larger
drops upon a leaf.
* * * * *
THERE are many other familiar examples of the principle of condensation,
the commonest of which is the so-called steam as it pours from the spout
of a kettle. In point of fact, it is not steam at all, but only water
condensed into very small drops. At the orifice of the kettle it is
quite invisible, but when it passes into the air, and is condensed, the
tiny globules become visible. The same fact may be noticed in the
Napier’s Coffee Machine, which has already been mentioned. When the
water is boiling in the glass globe no steam is visible, though the
upper portion of the globe is entirely filled by it. But, no sooner is
the cork removed, and the steam allowed to escape, than it at once
becomes visible as a white cloud, being, indeed, a miniature copy of the
rain-clouds that float above us.
* * * * *
THEN there is that mostly invisible passage of liquid through the
multitudinous pores of the body, which is generally known as
perspiration. It is invisible in warm weather, but on a cold day is as
visible as a rain cloud.
The Turkish Bath affords a good example of this fact. Sometimes the
hottest room attains a temperature of 250° or more, water boiling at
212°. When a bather goes into that room, he appears to have a perfectly
dry skin, the moisture being in the form of invisible steam, and swept
off as soon as it is generated.
But, if he passes at once into the cold room, he is so enveloped in
vapour that for a few moments he is wrapped in it as in a cloud, and
can scarcely be seen, the vapour having been condensed by the cold air.
[Illustration:
HEATED HORSE.
PERFUME SPRAY.
FREEZING BY EVAPORATION.
WET-BULB
THERMOMETER.]
A very familiar instance of this sudden condensation may be seen in the
streets of London on any winter day. There may be a couple of omnibus
horses, nearly at the end of their day’s work, and quite tired out.
Suddenly they are pulled up by the driver, and as suddenly disappear for
a moment or two, being concealed in a cloud of moisture proceeding from
their bodies. Of course in a hot day there is more of the moisture, but
the warmth of the atmosphere prevents it from condensation, and so it is
not visible.
One valuable property of the system of evaporation and condensation is
its cooling power. Thus it is that a person who is ill with fever tosses
about with a burning skin until the pores of the body act, and allow the
normal moisture to pass through them. Then the body cools by
evaporation, and the patient begins to amend.
So it is that the bather can endure in the Turkish bath a heat so great
that a glass of water, if held in the hand, would speedily boil, and a
piece of meat be cooked in about the same period. But, if the air were
not dry enough to carry off the perspiration, the bather would be
scalded to death.
A most valuable adaptation of the principle is shown in the little
glass machine for dispersing perfumes in the form of spray. In cases of
headache it is almost invaluable, the spray cooling the heated forehead,
like magic, and at the same time filling the room with the grateful
perfume.
It has even a greater claim to human gratitude, as I can personally
testify. I have the strongest objection to a surgeon’s knife, especially
when I know, from sad experience, that he is going to make very free use
of it. But, on the last occasion, I cared nothing for it, owing to the
happy invention called Ether Spray.
The effects were remarkable. First, a delicious cooling of a spot raging
with internal fires. Then it was rather colder than I liked. Then it was
much colder than I liked. Then it became almost too cold to bear,
reminding me of my childhood’s feet on the outside of the Birmingham
coach in the depth of winter.
Suddenly all sensation ceased, and the skin became white as parchment.
Out came the surgeon’s bistoury, and I looked at him with as calm
composure as if he had been whittling a deal plank. There was absolutely
no feeling whatever, the local nerves having been temporarily frozen, so
great is the power of evaporation. If it ever be my lot again to endure
cold steel, I shall have the ether spray.
* * * * *
ON the extreme right of the illustration is seen the “Wet-bulb”
Thermometer, which carries out the same principle, the thermometer being
double, and one bulb being covered with a wet envelope, while the other
is dry.
Below is one of the many inventions for making artificial ice, all of
them depending on the cooling power of evaporation. Perhaps some of my
readers may have seen molten iron poured over the human hand without
doing the least harm, or mercury frozen in a red, or rather a white, hot
vessel. Both these phenomena are due to the cooling power of
evaporation, which is made to act with extreme rapidity, and so absorbs
the heat until even mercury is rendered solid, and can be cast in a
mould like a leaden bullet.
* * * * *
IN the accompanying illustration we have an example of the Condensating
principle as applied to the steam-engine, and popularly known as the
“Low-pressure Engine.” In this case force is reconverted, so to speak,
and, if a cubic inch of water has been converted by heat into a cubic
foot of steam, creating a pressure in one direction, it can be
reconverted by cold, and so produce a pressure in another direction.
* * * * *
IT is owing to this fact that some parts of the world are always hot and
always wet, Guiana being a striking example.
[Illustration: RAIN-CLOUD.]
[Illustration: CONDENSER.]
The wind blows over the ocean, absorbing moisture as a sponge does
water. As it passes from the sea over the land, it is met by secondary
mountain ranges, too low to arrest its progress altogether, and high
enough to have their summits clothed in eternal snows. As soon,
therefore, as the warm, water-laden winds pass over these mountains, the
moisture is condensed by their frozen tips, and down rushes the rain in
torrents.
Even in our own temperate land we can often trace the cause of a heavy
rain to the presence of a lofty hill, or even an exceptionally tall
spire. The moist climate of Oxford has been attributed by scientific men
quite as much to its spires and towers as to its low-lying situation.
* * * * *
NOW we come to the various modes of extracting the water which is laid
up within the earth, and which only slowly ascends to the surface when
drawn up by the heat of the sun.
Water is everywhere, but the depths at which it is found are vastly
different. For example, at one house in which I lived it was not
possible to dig for three feet without coming to water. In another, no
water was found within some two hundred feet, and, as I several times
relieved the old gardener of the task of drawing the water for the day’s
consumption, I have reason to remember the depth.
[Illustration: SPRING.]
[Illustration: FOUNTAIN.]
The pail, rope, and winch which were in use at that time--and may be
still, to the sorrow of the gardener--are but a sort of semi-savage way
of procuring water from the depths of the earth. It is a well-known fact
that under certain conditions water always finds its own level, _minus_
the friction of the channel through which it passes. On this principle
all fountains are made. Those, for example, at the Crystal Palace, which
fling their waters to such a height, are fed from tanks on the summit of
the two great water towers. And, were it not for the friction of the
water in the tubes, and that of the air, the fountains would rise as
high as the tanks from which they are fed.
Such is the case with springs, especially with those of an intermittent
character, in which latter instance the rushing of the water is exactly
coincident with the filling of the hidden tank which supplies it.
The modern Hydrant system, which bids fair to supersede the cumbrous
machinery of fire-engines, even when worked by steam, is based on the
same principle. The water-tanks are placed at such a height that, when a
hose is attached, and the tap turned, the water can be thrown over the
roof of the highest building. Such hydrants have been attached to
Canterbury Cathedral since the fire which so nearly consumed that
magnificent and venerable building.
* * * * *
A VERY remarkable use has been made of this power of water in mining
operations. Most of my readers know that in gold mines the metal is
chiefly found scattered among quartz, one of the hardest of the
minerals. The usual plan has been to dig out the quartz, pound it to
powder with specially devised machines called “stamps,” to pass the
powder through mercury, which amalgamated with the gold, and gave it up
again on being heated to a certain temperature.
Now a different mode of mining is brought into operation, the pickaxe,
spade, and stamps, with all their expensive machinery, being abandoned,
and water made to do the duty of all three, some ingenious individual
having noticed the effect which water has on the hardest rock.
Such, for example, is the case with those wonderful Victoria Falls of
Africa, where the rushing water has cut its sinuous channel through so
many hundreds of yards of rock. Such, also, is the case with the more
celebrated, but not so wonderful, Falls of Niagara, which have been
gradually working their way backwards, having worn away the rocks over
which they fall, and which are shown to be many miles away from the spot
where the river first discharged itself over the cliff.
[Illustration: HYDRAULIC MINING.]
[Illustration: WATER-FALL.]
In fact, it is well known that the Falls are receding at a definite rate
annually, and that the rate has been calculated with scientific
accuracy. The cliffs of our own coasts-say of Margate or
Ramsgate--crumble away with equally calculable speed.
In the hydraulic mining system large tanks are erected, at least two
hundred feet above the level of the mine. From these tanks proceed
pipes, terminated by hose, just like those of our ordinary fire-engines.
The miners, instead of using pickaxe or crowbar, simply direct the
streams of water against the solid rock. Their effect is tremendous.
They tear it to powder, and carry it down the wooden troughs called
“flumes,” in which the mercury is so arranged that not a single atom of
quartz rock can pass without having its gold extracted.
The following graphic account of Hydraulic Mining at Nevada is taken
from Mr. J. K. Lord’s “Naturalist in British Columbia:”--
“Near Nevada are the famed Hydraulic washings. The gold is disseminated
through terraces of shingle conglomerates, often three hundred feet in
thickness. These terraces are actually washed entirely off the face of
the country by propelling jets of water against them, forced by pressure
through a nozzle.
“To accomplish this, the water is brought in canals, tunnels, and wooden
aqueducts, often forty miles away from the ‘draft.’ This supply of water
the miners rent.
“As we near the washing spot, in every direction immense hose, made of
galvanized iron, and canvas tubes six feet round, coil in all directions
over the ground like gigantic serpents, converging towards a gap, where
they disappear.
“On reaching this gap, I look down into a basin or dry lake, three
hundred feet below me. The hose hangs down this cliff of shingle, and
following its course by a zigzag path, I reach a plateau of rock, from
which the shingle has already been washed.
“A man stands at the end of each hose, that has for its head a brass
nozzle. With the force of cannon-shot, water issues in a large jet from
this tube, and propelled against the shingle, guided by the men, washes
it away as easily as we could sweep a molehill from off the grass.
“The stream of water, bearing with it the materials washed from out the
cliff, runs through wooden troughs called ‘flumes,’ floored with
granite. These ‘flumes’ extend six miles. Men are stationed at regular
distances to fork out the heavy stones.
“Throughout its entire length, transverse strips of wood dam back a tiny
pond of mercury. These are called _ruffles_--gold-traps, in other words,
that seize on the fine dust-gold distributed through the shingle. The
flumes are cleaned about once a month, and the gold extracted from the
mercury.
“I try with a powerful lens to detect gold amidst the material they are
washing, but not a trace is discoverable, and yet it pays an immense
profit to the gold-washers.”
* * * * *
THERE are two more modes of extracting water, which will be but
cursorily mentioned.
The reader will remember that water finds its own level, and that the
terrific power of hydraulic mining is owing to the fact that the water
expends its force against the solid rock instead of ascending into the
air.
[Illustration: ARTESIAN WELL.]
[Illustration: NORTON’S TUBE.]
It is now found that, even without artificial assistance, water has a
habit of finding its own level, and that, if it be allowed its own
course, it will contrive to find its way nearly to the highest point
whence it derived its origin. On this principle are based the Artesian
Wells, which, when they “strike water,” spurt it up in a torrent, as is
the case with the now celebrated Norton Tubes, which are screwed down
into the earth like hollow gimlets, and which always contrive to extract
the water hidden beneath the surface of the earth.
The success of our army in Abyssinia was greatly owing to these Norton
Tubes, which, being of small diameter and of peculiar make, could be
screwed into the ground when the troops made a halt, unscrewed when they
left the spot, and used again for the next halt.
Similarly, the French used the Artesian-well system with wonderful
success in Northern Africa. Water is the chief necessity of life in that
part of the world, and a nation who could cause pure cold water to
spring out of the hot and thirsty sands was naturally looked upon as
something more than human.
Yet the principle was exactly the same in both cases. Water is always
latent somewhere beneath the surface of the earth, and, if a tube can be
driven deep enough, the water will come up it.
The accompanying illustration shows the Artesian Well and Norton’s Tube,
and their similitude in principle, the tube penetrating through various
layers of soil, until it reaches the water which it seeks.
* * * * *
THEN there is another way by which water can be made to force itself to
a considerable height. Not being much of a mathematician, I do not
recollect the exact proportional height to which a stream of water may
raise itself, but if any one can secure a fall of some eight or ten
feet, he can furnish his house with water by means of the “Ram,” a chart
of which is shown in the illustration.
[Illustration: SPOUT-HOLE.]
[Illustration: WATER-RAM.]
The principle of the Ram is, that the water is allowed to flow down a
tube, when it meets with a valve. This valve is suddenly closed by the
pressure, and the water is forced onwards by the shock. Much water
escapes at each blow of the valve, but that does not signify.
The force of water thus suddenly stopped is hardly appreciated. Even in
ordinary houses the sudden turning of a water-tap has been known to
burst the pipe and deluge the house with water.
* * * * *
IN Nature a similar effect is produced, called popularly the
“Spout-hole.”
It is a hole or tunnel on the seashore, passing upwards from the level
of the sea to the summit of the cliff.
When the waves are urged against the tunnel by the wind, the water is
dashed into it. Being partially checked by the friction, which acts
exactly like the water that is checked by the Ram, the wave hurls itself
up the channel, and flies out in showers of spray, high above the level
of the original wave which caused it.
In the illustration are shown the Water-ram with its globular valve, and
the safety or escape valve of the waste water. On the left is shown one
of the natural Spout-holes, with the water dashing through its tunnel
into a mass of spray.
USEFUL ARTS
CHAPTER XI.
AËROSTATICS.--WEIGHT OF AIR.--EXPANSION BY HEAT.
Ascent and Descent.--The Balloon and the Parachute.--Description of
the Balloon.--The Montgolfier Balloon.--Causes of its
Abandonment.--The Gas Balloon.--Hydrogen Gas and its
Manufacture.--The Gossamer Spider.--Reasons of its Ascent and
Descent.--Many Species of Gossamers.--Description of the
Parachute.--Its Mode of Action.--A Balloon converted into a
Parachute.--Toy Parachutes.--Natural Parachutes.--The Dandelion
Seed and its Structure.--The Flying Squirrel.--The Flying
Monkey.--Flying Mice and Flying Opossums.--The Flying Dragon and
its Pseudo-wings.--The Flying Frog.--Weight of Air.--Pressure per
Square Inch.--The Air Ocean and its Storms.--Principle of
Air-currents.--The Sun, the Earth, and the Air.--Ventilation of
Mines.--Choke-damp and Fire-damp.--The Air-shafts.--Chimneys of
Factories.--The Steam-blast.--The Barometer, and Mode of its
Construction.--Water and Mercury.--Sucking Eggs and
Sugar-cane.--Expansion of Water and Metals by Heat.--The
Thermometer.--Wheel-making.
AËROSTATICS.
We will begin this chapter with the only two modes at present known by
which man can ascend from the earth or descend to it with safety,
namely, the Balloon and the Parachute, the latter being generally
attached to the former, and detachable at pleasure.
The Balloon is, in fact, as its name imports, a large, hollow, air-tight
ball, filled with some substance lighter than ordinary air. The original
Balloons by Montgolfier were filled with heated air exactly like our toy
fire-balloons. Just as the supply of hot air is kept up in them by a
sponge dipped in lighted spirits of wine, so in Montgolfier’s balloons
the same object was attained by straw which was kept continually burning
in a grate.
There were, however, two disadvantages about this plan. The first was
the great danger of fire, which on one occasion did ignite a balloon
when at a great height. The second was the perpetual labour required in
keeping the fire alight. Straw burns very rapidly, and so the aëronaut
had no opportunity of making those meteorologic observations in which
consist almost the entire value of the balloon.
[Illustration: GOSSAMER SPIDER. BALLOON.]
Then it was thought that hydrogen gas, being about fourteen times
lighter than ordinary air, would answer the purpose, and such has proved
to be the case. Formerly the gas was made at great expense from
sulphuric acid and zinc, but it is now found that the common coal-gas is
quite as efficient, very much cheaper, and fills the balloon much more
rapidly.
* * * * *
THE same principle, though not the same form, is found in Nature.
There are certain tiny spiders called Gossamers, which have a curious
power of floating in the air. They have been seen on the tops of lofty
spires, and they are sometimes so numerous that the air is full of their
floating webs, and the ground is white with those that have descended.
Their mode of ascent is this. They climb to the top of some elevated
object, if it be only a grass-blade. They then pour out a tuft of long,
slender threads, which shortly begin to tend upwards. As soon as the
Spider feels the pull, it crawls upon the web, and sails away into the
air. The duration and height of the ascent depend much on the wind and
character of the atmosphere.
The web ascends because it is for the time lighter than the atmosphere.
But, as it gradually becomes laden with the moisture that more or less
fills the air, it becomes heavier than the atmosphere, and gently sinks
to the ground.
What may be the object of these aërial voyages no one knows. They may be
for the purpose of capturing minute insects, or they may be for mere
amusement. But in either case they are highly instructive, as showing
the principle on which the balloon was framed.
The little Gossamer Spider is shown on the left hand of the
illustration, clinging to its floating web. I believe that the Gossamer
is not a single species of Spider, but that there are many species which
deserve the name, being able to float in the air when they are small,
but losing that capacity as they increase in size and weight.
* * * * *
NOW we come to another branch of the same subject, namely, the safe
descent from a great height by means of the Parachute.
On the right hand of the illustration is the ordinary Parachute as it
appears when open and closed, in either case having somewhat the
appearance of a large umbrella. It is hung to the balloon in its closed
state, and when detached it falls rapidly for a yard or two with
startling rapidity. The pressure of the air thus forces the ribs open,
and gives sufficient assistance to the atmosphere to insure a gentle
fall.
On one memorable occasion, when the late Albert Smith was in the car of
a balloon upwards of a mile from the ground, the balloon burst.
Fortunately it burst so completely, that the silk was driven into the
closely meshed netting, and formed an extemporised parachute, which took
the voyagers to the earth with safety, except some rather severe
bruises.
Children often amuse themselves with miniature parachutes. They take a
square piece of thin paper, tie threads to the four corners, and then
bring the ends together, a cork taking the place of the car. They then
launch it from a high window, and should there be a favourable breeze,
it is wonderful how far it will be carried before it comes to the
ground.
Once, when a boy of eleven, and consequently thoughtless, I set a
chimney on fire by one of these Parachutes. I wished to see whether it
would go up the chimney, and come out at the top. Unfortunately it was
caught by a flame as it was launched, flew up in full blaze, and, as the
chimney needed sweeping, the result was inevitable.
* * * * *
[Illustration:
FLYING SQUIRREL. DANDELION SEED PARACHUTE
FLYING DRAGON. (OPEN AND CLOSED). (OPEN AND CLOSED).
FLYING FROG.]
In the centre of the illustrations, and at the top, are two examples of
a well-known natural Parachute called the Dandelion seed. The
resemblance to the real Parachute is wonderful, the actual seed
occupying the place of the car, and fulfilling the same office, _i.e._
keeping the seed upright until it reaches the ground.
When the tuft is closed, as is the case before the pretty ball of seeds
bursts from the green envelope in which they had been confined during
the process of development, its form bears the same startling
resemblance to the Parachute.
* * * * *
PASSING from the vegetable world, there will be seen three examples of
Natural Parachutes. Several others will be mentioned, but we have no
space for description or figure. It will be seen, however, that the one
principle which characterizes them all is the exposure to the air of a
flattened and large surface, in proportion to the size of the object.
Before beginning the description, however, I must mention that nearly
all animal parachutes can to a certain extent guide their course, while
neither the balloon, the gossamer, the parachute, nor the various winged
seeds have the least power of guidance, but must follow every current of
air in which they may happen to float.
* * * * *
THE upper figure represents a Flying Squirrel.
There are many species of Flying Squirrel, but they all agree in one
point. The skin of their sides is modified into a very thin fold, which
extends as far as the feet.
It is very elastic, so that when it is not in use it falls into folds or
wrinkles, and is hardly perceptible. But should the Squirrel wish to
pass from one tree to another, without coming to the ground, it spreads
its legs as widely as possible, so as to stretch the membrane into a
wide, flat surface. It then boldly springs into the air, and sweeps upon
its mark with a sort of skimming movement. Except that it does not
revolve, it passes through the air much after the fashion of an
oyster-shell when thrown horizontally.
Many mammalia are constructed after a similar fashion, such as the
Colugo, or Flying Monkey, the Flying Mice, and the Flying Phalangists,
or “Opossums,” as they are popularly called.
* * * * *
IN the centre is the Flying Dragon, or small lizard, which very probably
gave rise to the fabled Dragons in which our ancestors so devoutly
believed. Indeed, on looking back at the old illustrated works on
Natural History, there can be but little doubt on the subject.
In this creature, the ribs, instead of the legs, carry the flat and
elastic membranes. When simply crawling on the branches, after the
manner of tree-lizards, the ribs lie flat against the sides, and the
membranes collapse, so that the shape of the body is little different
from that of any crawling lizard.
But the ribs are movable at will, and, when the creature wishes to pass
from one tree to another, it extends the ribs, stretches the membranes,
and launches itself into the air, exactly as has been narrated of the
Flying Squirrel.
* * * * *
THE lowest figure represents a most extraordinary animal, called the
Flying Frog. Only one specimen is believed to be known, and that was
discovered in Borneo by Mr. Wallace.
Here we have an analogy with the bats of the present day and the
pterodactyles of the past, namely, the elongation of the toes, and the
stretching of a web between them. In the two latter animals, however,
only the toes of the two fore-legs are elongated, whereas, with the
Flying Frog, the elongation is found in both pairs of limbs. The ends of
the toes are furnished with adhesive pads, like those of the tree-frogs,
to which it is probably related.
By means of the four membranes, the creature is able to sweep through
the air for some distance, and, indeed, this power was the reason why it
was caught. It was seen to skim from one tree to another, and was
immediately secured. Had it remained sticking on the tree, it would
probably have escaped observation.
WEIGHT OF AIR.
We have already noticed that hydrogen gas is fourteen times lighter than
air, and infer necessarily that the weight of the atmosphere must be
very considerable if so heavy an object as a balloon, with its car,
instruments, sand-bags, and passengers, can rise and float in it.
We are not conscious of its weight, because it permeates us, and the
pressure is neutralised. But, in fact, we live at the bottom of a vast
ocean which we call the atmosphere; and as, on an average, there is a
pressure of fifteen pounds on every square inch of surface, we have to
sustain an almost incredible weight. Let, for example, any one measure
the surface of his own hand, reduce it to square inches, add together
fifteen pounds for every square inch, and he will then appreciate the
weight of the atmospheric ocean in which we live. On an average, every
human being endures a pressure of some ninety thousand pounds.
This ocean is in perpetual movement, sometimes violently, which we call
storm; sometimes gently, which we call breeze; and sometimes very
gently, which we call calm. There are air-spouts as well as
water-spouts; and, in fact, the water-spout is nothing but a continuance
of the air-spout, as is shown by the moving sand-columns of the desert.
Whatever may be the character of the winds, as we call this movement,
the air is never for a moment still; and, indeed, were it to be still
for any time, the whole human race would perish.
How winds are caused we shall see by the aid of the diagram on the
left-hand side of the illustration.
[Illustration: AIR-CURRENTS. VENTILATION OF MINES.]
The original cause is the sun. His rays fall upon the earth, heating it,
and so by radiation heating the air. Now, as has been remarked, heated
air will cause a heavy balloon to float through ordinary air, and to
carry up a considerable amount of dead weight besides; consequently the
heated air must ascend, while cool and heavier air rushes in to take its
place, and thus the currents are produced. Were the earth set straight
upright, the currents would invariably run in one direction; but, as it
is tilted on one side, the needful variety is obtained, and we find the
winds blowing from all parts of the compass.
The principle, therefore, of all winds is, that heat expands, and
therefore becomes lighter than air at an ordinary temperature.
* * * * *
WERE it not that man has taken advantage of this principle, there could
not be a deep mine in England. In any deep excavation, even though it be
a well, foul air, mostly composed of carbonic acid gas, always collects,
and, being much heavier than atmospheric air, lies at the bottom of the
pit as surely as hydrogen would rise out of it. To breathe this air is
as certain and as sudden death as to take prussic acid, and no mine can
be worked as long as “choke-damp” is in it.
In coal mines there is an additional source of danger, namely, the coal
gas, which is nearly identical with our coal gas of the streets, and
takes fire when brought into contact with flame. To rid the mines of
these gases, a simple, ingenious, and effectual remedy is used. A
ventilating shaft is made, which reaches from the bottom to the mouth of
the pit. At the bottom, diagonal shafts are made, entering the main
shaft, as shown on the right hand of the illustration. One of these is
connected with a furnace, and the other, or others, open into the mine.
The heat of the furnace rarefies the air in the shaft, causing it to
rush upwards with great violence, and so, by creating a partial vacuum,
to force the air in the shaft to follow it. The loss of air thus caused
is supplied by fresh air from above, which, by the law already
described, is obliged to take the place of that which was driven out.
Thus a complete circulation of air is kept up, and a well-managed mine
has a fresher atmosphere than many houses in which the windows are
mostly kept shut, and the only ventilation is accomplished by
occasionally open doors.
The “draught” of our domestic chimneys is owing to this principle, and
the reason why factory chimneys are built of such enormous height is,
that the column of heated air may be increased, and consequently that
the draught may be stronger, and the heat of the furnace made fiercer.
The “Steam-blast,” by which the escape steam of engines is sent into the
chimney, is another example of this principle, the steam taking the
place of the hot air.
Further examples of the weight of the atmosphere are given in the
illustration. That on the right represents the common Wheel Barometer,
which marks the weight of the air by a hand moving in front of a dial.
If the hand moves towards the right, the weight of the air is
increasing; if to the left, it is decreasing.
There are certain words, such as Wet, Change, Fair, Dry, &c., on the
face of the dial, but they are only conventional, the real test of the
weather being the direction in which the hand moves. For example, if
with a west wind the hand moves from Dry towards Fair, rain may be
expected; whereas, if it should move from Wet to Change with an east
wind, we may reasonably think that fine weather is coming.
The whole cause of this revolution of the hand may be found in the
weight of the atmosphere.
It is found that a column of water thirty feet high, or a column of
mercury thirty inches high, is exactly equal in weight to a column of
air of the same diameter, but some forty odd miles high, so that the two
columns precisely balance each other.
[Illustration: SUCKING SUGAR-CANE. SUCKING AN EGG. BAROMETERS.]
Suppose, then, the water or mercury to be placed in tubes closed at the
top and open at the bottom, the water or mercury will exactly balance
the air, and will not escape from the tubes. It necessarily follows that
if the air be heavier than usual, it will force the liquid higher into
the tubes, and, if it be lighter than usual, will allow them to fall
lower. This is the principle of the Barometer.
The mechanism of the hand and dial is shown in the diagram which
occupies the centre of the illustration. For convenience, sake the
mercury column is mostly employed, but several Water Barometers, some
thirty feet in length, have been constructed.
* * * * *
ON the left hand is seen a boy engaged in sucking an egg. The plan
employed is simple enough. A tolerably large hole is made at one end,
and a very small one at the other. The yolk having been broken up by a
long needle, or similar implement, the larger hole is placed to the
lips, and, suction being used, the contents pass into the mouth.
Were it not for the hole at the end opposite the mouth, it would be
impossible to extract the contents, but the air rushes through the
aperture, and so forces out the contents of the egg.
Above is a representation of the way in which Sugar-cane is sucked. The
reader probably knows that the Sugar-cane, like the wheat-stem, has
knots at certain intervals, which divide the cane into a number of
separate parts.
There is quite an art in sucking the Sugar-cane. If a joint be cut off,
and the lips applied to the end, not a drop of the sweet juice would be
extracted. But if a notch be cut close to the joint, as shown in the
illustration, the air can gain access, and then the juice flows easily
enough.
* * * * *
[Illustration: BOILING WATER.]
[Illustration: THERMOMETER.]
It has already been mentioned that air expands when heated. The same
rule holds good when applied to other objects, such as the various
liquids, metals, &c. A very familiar example of this fact is the
“boiling over” of water, when the vessel has been filled too much to
allow for the expansion of the heated liquid.
Advantage has been taken of this principle in the formation of the
Thermometer, a word which signifies “heat-measurer.” Liquid of some kind
is placed in an hermetically sealed tube, generally terminating with a
bulb, and in proportion to the heat the liquid expands, and is forced up
the tube.
Any liquid will answer to a certain extent, but, as water freezes at
32°, it would be useless for measuring degrees of cold below the
freezing point. Coloured spirits of wine are used; but the very best
liquid is mercury, which is a metal in a state of fusion.
This expansion by heat is so powerful in iron, that it is utilised in
several ways.
Take, for example, wheel-making. The iron tire is made rather smaller
than the wheel, and is then placed in a fire until it is red-hot. It
then expands so much that it can be easily slipped over the wheel as it
lies on the ground. Cold water is then dashed on it, and the tire
contracts with tremendous force, binding the parts of the wheel firmly
together.
In all buildings where iron is much used, such as iron bridges, iron
beams, &c., it is necessary to make allowance at both ends, so as to
permit the iron to expand on a hot day and contract on a cool one.
Buildings formed of stone and iron were once thought to be safe in case
of fire. They are now known to be just the contrary, the stone flying
with the heat, and the iron expanding.
USEFUL ARTS.
CHAPTER XII.
The Cassava Press and its Structure.--Mode of using it.--The
Siamese Link.--An ingenious Robbery.--Muscles and their Mode of
Action.--Human Arms and Steelyard.--Change of Direction.--The Human
Hand and Wrist.--Story of a Carpenter.--The Pulley.--Reduction by
Friction.--Past and present Engines.--Oiling Machines.--Treatment
of the Sewing Machine.--Use of Paraffine.--Disuse of Machine
hurtful.--Human Joints.--Synovia and its Value.--Disuse of Joints
hurtful.--The Lazy-tongs and its Usefulness to
Invalids.--Suggestions for Improvement.--Larva of the Dragonfly and
its Mask.--Curious Mode of seizing Prey.--Proboscis of the
Housefly, and Mode of using it.--The Apple-parer.--Squirrel and
Nut.--Structure of Teeth.--Rock-splitting.--Powers of Ice.--How the
Pebble-ridge is formed.--Splitting Stones by Moisture.--The Diamond
Drill.--Ovipositor of the Gad-fly.--Curious Similitude of
Structure.
MEANS AND APPLIANCES.
In this chapter we will take some miscellaneous appliances of force both
in Art and Nature.
In the accompanying illustration is shown the Cassava Press of Southern
America, a most effective and simple instrument for extracting the
juices of the root. These juices are poisonous when raw, but, when
properly boiled and cooked, they make an excellent sauce.
The press in question is an elastic tube made of flat strips of cane
woven together exactly like the “Siamese Link,” which will be presently
described. The cassava root, after having been scraped until it
resembles horseradish, is forced into the press until it can hold no
more. The result is, that the tube is shortened and thickened, being
widest in the middle.
It is then hung by its upper loop to the horizontal beam of a hut. A
long pole is passed through the lower loop, the short end is placed
under a projecting peg on the upright post of the house, and a heavy
weight attached to the longer end. A powerful leverage is thus obtained,
the tube is forcibly shortened, and the juice exudes through the
apertures of the woven cane.
[Illustration: CASSAVA PRESS.]
When it begins to run slowly, a woman seats herself at the end of the
pole, so as to increase its weight. I must mention here that in the
illustration the press is too near the middle of the pole. This is
because the exigences of our page do not admit of the requisite length.
But if the reader will kindly assume the end to which the stone is
attached to be three or four times longer, he will have an idea of the
great power which is exerted upon the cassava.
On the left hand of the illustration is the same cassava press as seen
when empty, and both figures, as well as that of the pot for receiving
the juice, are taken from specimens in my collection.
* * * * *
ON the right hand of the following illustration is the Siamese Link,
which caused such a sensation when it first came out.
A finger is inserted at each end, and, when the owner attempts to
withdraw them, the Link contracts, and the harder the pull, the tighter
is the hold. If the fourth instead of the first finger be employed, the
hold of the Link is exceedingly strong.
The only mode of release is by pushing the fingers together, when the
Link will relax. It should then be held by the remaining fingers of one
hand, so that it shall not contract again, and the finger of the other
hand comes out at once.
An ingenious robbery was once committed by means of the Siamese Link. A
man of good address struck up an acquaintance with a jeweller. One day
he produced a Siamese Link, and challenged him to get his fingers out
when once they were in. So the jeweller was told to put his hands behind
his back, and push his little fingers as far in as he could.
[Illustration: MUSCLES Of LEG.]
[Illustration: SIAMESE LINK.]
This he did, when the treacherous friend made a clean sweep of all the
rings, brooches, ear-rings, and such jewellery as was within his reach,
while the unfortunate jeweller was vainly tugging at the Link. This only
occupied a few seconds for a practised hand, and the thief quietly
opened the door, shut it, and was lost in the passing crowd before the
jeweller could recover from his surprise.
* * * * *
ON the left of the same illustration is a view of the muscles of the
human leg, which, as the reader will see, are curiously like the
distended cassava press. Although the mode of applying the force
differs, the principle is the same.
In the latter case an external force is applied to the press, but in the
latter an internal, or rather a central, force is applied to the bones.
It is evident that if a similar process were carried on with the cassava
press, and the central portion forcibly distended, the supports at
either end would be drawn powerfully towards each other. Substitute the
muscle for the press, and the bones for the poles, and this is muscular
action.
* * * * *
HERE we have a diagram which speaks for itself, as far as muscular
action is concerned, but there is another point to which we shall
presently pass.
[Illustration: HUMAN ARM.]
[Illustration: STEELYARD.]
The muscle of the arm is seen running along the bone, passing over the
elbow, where it is held down by a tendinous band, and, by its
contraction, enabling the arm to be bent so as to uphold a considerable
weight. The mechanical analogy between this arrangement and the common
Steelyard is too evident to need any explanation except inspection of
the diagram.
* * * * *
THERE is, however, another point which is worthy of consideration. The
muscle does not proceed at once from the shoulder to the wrist, but
passes under the tendinous band above mentioned, and so produces a
change of direction when the arm is bent.
There is a more complicated arrangement of a similar character in the
human hand, a diagram of which is given in the left-hand figure of the
accompanying illustration.
The fingers are, of course, moved by a set of tendons, and the muscles,
from which these tendons spring, are attached to the fore-arm (I
purposely omit the scientific titles, though they would be much easier
to write). Any of my readers can prove this for themselves.
Let him first grasp the upper arm firmly, and bend the limbs, and he
will at once find that the swelling of the muscle shows the source of
power.
Then let him do the same, but grasp the fore-arm, and he will find that
the muscles are quiescent, showing that the former set of muscles belong
to the entire arm, and not to the fingers, while the muscles of the
lower arm have nothing to do with the bending of that limb.
Now let him grasp the fore-arm, and open and close the fingers, and he
will feel a whole set of muscles rise, and swell and harden under his
grasp. Next let him bend his hand inwards, and he will find that the
fingers work perfectly well, though the direction of force is changed.
This is owing to a band of tendons passing across the wrist, under which
the finger-tendons play. The course of the tendons is marked in the
illustration by leaving them white.
The wondrous structure of the human hand and its multitudinous tendons
can only be appreciated by actual dissection, but an idea of their
variety and use may be obtained by watching the hands of a skilful
pianoforte-player. This struck me forcibly the first time that I ever
heard Thalberg play.
While on the subject of tendons, I may mention a curious case. A
journeyman carpenter missed a blow with his axe, and struck his left
hand at the junction of the thumb and wrist. The important tendon was
severed, and the inner muscles, having no counteracting force, dragged
the thumb into the hollow of the hand.
To all appearance, the man could no longer earn a living as a carpenter.
But he would not be discouraged, and while he was in hospital he
borrowed a book, and studied the anatomy of the human hand. By means of
this knowledge he constructed a sort of semi-glove, in which he
introduced pieces of watch-spring, that supplied the place of the lost
tendon.
Not content with this, he studied Euclid for the purposes of his trade,
so as to get the most possible out of a piece of wood of given
dimensions, and be able to go straight to his mark by a problem, instead
of doing it slowly and clumsily with a two-foot rule and a pair of
compasses. When I saw him last he was a master carpenter in a large and
increasing business.
Man has unconsciously imitated Nature in the invention of the Pulley,
whereby the direction of force may be altered almost at will. In this
case the cord takes the part of the working tendon, and the Pulley of
the fixed tendinous crossbar. There is much matter of interest in the
tendons, but, as our space is fast waning, I must resist the temptation
of describing them.
* * * * *
IN all machinery one of the chief objects of the machinist is to reduce
friction as much as possible. He makes all the joints as smooth as tools
can polish, and always introduces oil or some lubricating substance into
the joints. Otherwise the engine rattles with a noise proportionate to
its power, and wastes its force on the friction.
[Illustration: TENDONS OF HAND.]
[Illustration: PULLEY.]
In my childish days a steam-engine of any kind used to rattle so loudly
that conversation was almost impossible. Now they are made with such
perfection, that the vast engines in use at the pumping stations of the
metropolitan drainage are almost absolutely silent.
There is the enormous hall, filled with gigantic beams and rods, and
cranks, and wheels. A single man turns a little handle, and the whole
machinery starts into life. Beams rock, cranks and wheels revolve, rods
slide up and down, and all in a silence which is nearly appalling in its
manifestation of unassuming strength. Indeed, many a hand sewing
machine makes far more noise than one of those giant engines, and all
because in the latter friction is avoided as far as possible, every
screw is well braced up, and every joint is kept well lubricated.
Here I may observe that few sewing machines get fair play. They rattle,
they squeak, they become stiffer daily, they snap the thread, and then
decline work altogether. And in almost every case this is done by
neglect on the part of the owner, who does not lubricate every point of
the machine which works upon another.
[Illustration: LUBRICATION OF JOINT.]
[Illustration: OILING MACHINE.]
Ladies especially are very careless in this respect, and will mostly
omit three or four of the oiling points. They might just as well omit
them all, as a single unoiled point will disarrange the harmonious
motion of the whole machine. I have often been called in as surgeon in
such cases, and have almost invariably been able to point to several
spots which needed oil, and did not get it. Sometimes, out of false
economy, an inferior oil is used, which speedily clogs and hardens, and
stops all movement. In such a case the best remedy is to apply paraffine
liberally, and use it for a quarter of an hour or so. It will soon
dissolve the clogged oil, which may be worked out by turning the handle
or crank of the machine.
Of course the best remedy is to take the machine to pieces, polish the
joints, lubricate them, and put it together again. But this is a
perilous process, and an amateur, if he tries it, will generally find
himself with half-a-dozen pieces for which he can find no place.
Paraffine will answer every purpose, and I have released many a
stiffened machine by its use.
Then some people leave their machines untouched for days, or even weeks,
and then wonder that they work stiffly. Every day the machine should he
worked, if only for a few seconds, and then it will seldom stiffen. It
is just the same with steamers. When they are in harbour, though the
fires be out, and they are not meant to move for weeks, the engines are
always turned round at least once daily.
* * * * *
BOTH these rules hold good in the animal kingdom.
To every joint there are attached certain glands that supply a kind of
oily substance technically named “synovia,” which acts exactly the same
part as the oil or grease of machinery. If these glands do not do their
duty, and the supply of synovia be defective, the joints become stiff,
painful, and crackle when they are moved.
Then, exactly as the joints of a machine become stiff from non-usage, so
do those of a human being. We will take, for example, the Indian Fakirs
who vow that they will not move some limb from a definite posture. At
first the exertion is trying and painful, but by degrees the disused
joints lose their faculty of motion, and, even if their owner wished to
move a limb, he could not do it.
The right-hand figure of the illustration represents the lubrication of
an ordinary sewing machine, and the left-hand figure is a section of the
human knee-joint, showing the gland which supplies the synovia.
* * * * *
PERHAPS some of my readers may think that such a subject as the
“Lazy-tongs” is too trivial for a work which deals, however lightly,
with science. But there may be some who know the inestimable benefit of
Lazy-tongs under certain conditions.
There are many cases where a severe injury has occurred, or where
rheumatism has fixed its tiger-claws in the joints, so that movement is
all but impossible. There may be no one in the room to help the invalid,
and even to stretch the arm over the table is as impossible as to jump
over the house.
Then it is that the real value of the Lazy-tongs becomes manifested, and
that it shows itself in the light of a supplementary limb. With a mere
movement of the fingers it can be stretched across any table which is
likely to be placed before an invalid, and seize the required object by
the tongs at the further end.
The only drawback to its use is, that the instrument cannot be shortened
without opening the tongs. But, if some plan could be devised whereby
the tongs could retain their hold under those conditions, the instrument
would be a perfect one.
* * * * *
EXACTLY such a Lazy-tongs we have in Nature, in the well-known “mask of
the larva and pupa of the Dragon-fly.” It is called a mask because, when
closed, it covers the face.
[Illustration: HEAD AND PROBOSCIS OF HOUSE-FLY.]
[Illustration: MASK OF DRAGON-FLY LARVA.]
[Illustration: LAZY-TONGS.]
It chiefly consists of two flat, horny plates, hinged in each other like
a carpenter’s two-foot rule, and being capable of extension to a
considerable length. The end is widened, and furnished with two jaws,
which take the part of the tongs in the instrument above described.
This curious apparatus is used for the purpose of securing prey.
I have kept many of these creatures, and watched their mode of feeding.
As has already been mentioned, they have two modes of progression,
_i.e._ walking by means of legs like those of ordinary insects; and
driving themselves along by ejecting water from the tail, on the
principle of the rocket. As far as I have seen, the latter mode is
always used in taking prey. The Dragon-fly larva always lives at the
bottom of the water, though it can force itself to the surface if
needful. And, like the dreaded ground-shark, it seizes its prey from
beneath.
Its favourite food is the larva of the whirlwig-beetle, a fat white
grub, with a number of white, soft, feathery gills fringing its sides.
In order to produce a current of air over these gills, the larva
wriggles itself up to a height of several inches, and then sinks slowly
down, with the white gills floating on either side.
Should a Dragon-fly larva be near, it sees the grub ascending, glides
quietly under it without using its legs so as to cause alarm, waits for
it to sink, darts out the mask, seizes it in the jaws, drags it to its
mouth, and the grub is seen no more. So voracious are these larvæ, that,
if only two are kept in the same vessel, one is sure to devour the
other.
* * * * *
ANOTHER good example of the Lazy-tongs is the Proboscis of the common
House-fly. We have all seen these insects alight near sugar, or any
other tempting food, unfold the proboscis, pour a drop of liquid in the
sugar, dissolve it, suck it up, and then shut up the proboscis as if by
hinges.
* * * * *
ANOTHER labour-saving machine is the Apple-parer, a comparatively modern
invention. The principle is, that a knife is pressed lightly by a spring
against a revolving apple, and set at such an angle that nothing but the
outside peel can be removed. Where large numbers of apples have to be
pared, as in making preserves or in hotels, this is a most useful
invention.
[Illustration: SQUIRREL AND NUT.]
[Illustration: APPLE PARER.]
When I first saw it at work, the operation seemed familiar to me, but I
could not at first remember the parallel. At last it flashed across me
that a Squirrel eating a nut was the natural parallel of the Paring
Machine.
After splitting the shell and extracting the kernel, the Squirrel takes
the latter between its fore-paws, presses it against its upper incisor
teeth, and makes it revolve rapidly. In a second or two the kernel is
perfectly peeled, and is then eaten.
In this case the incisor teeth of the Squirrel take the part of the
knife, the muscles of the leg that of the spring, and the sharp edges of
the upper teeth that of the knife. The structure of the Rodent teeth has
already been explained in page 233.
* * * * *
THE wonderful effects of water in breaking up the hardest rock have
already been described. We will now proceed to another branch of the
same subject.
[Illustration: FROST-CLEFT ROCK.]
[Illustration: STONE-SPLITTING.]
Perhaps some of my readers may have wandered along our rocky coasts, and
have seen how large masses of rock are continually detaching themselves,
though they are so hard that a cold chisel is needed to make any
impression upon them.
Then they fall into the sea, and are rolled backwards and forwards until
they become smoothed and rounded, and are called pebbles, while the
portion that is rubbed off them is called sand. The phenomenon is well
shown in the wonderful Pebble Ridge of North Devon.
The real agent is ice.
We all know that, when water freezes, it expands considerably. This
accounts for two phenomena.
First, as it expands, it becomes lighter than water, and consequently
floats on the surface.
Next, there are few of us who have not seen water-bottles cracked by
the freezing of the water. The most common, and perhaps the most
unpleasant, example of this propensity is the bursting of water-pipes in
the winter, followed by a flooding of the house when the thaw comes.
This is caused by the expansion of the frozen water, which will burst
not only a thin leaden tube, but a stout iron vessel. Care should
therefore be taken, at the beginning of winter, to cover up all exposed
portions of leaden pipes, and there will then be no danger. There was
one pipe in my house that was always bursting, but after I covered it
with two or three layers of carpet placed loosely over each other, so as
to entangle the air and form a non-conductor, the pipe has never frozen,
and the water supply has been uninterrupted by the severest frosts.
I am told that a still better plan exists, especially in places where
the pipes cannot be thoroughly protected by external wrappings. Let six
inches or so of the leaden pipe be removed, and its place supplied by a
vulcanised india-rubber tube.
The ice _must_ expand somewhere, and chooses the spot where least
resistance is offered to it. Consequently, it expands in the
india-rubber tube, but does not break it, and, when the thaw comes,
there is no overflow of water.
* * * * *
MAN utilises this power of ice in stone-splitting. Instead of taking the
trouble to cut the stone by manual labour, the workmen bore a series of
holes, fill them with water, insert tightly a wooden plug to prevent the
ice, when formed, from oozing out of the holes, and leave the rest for
the frost to do.
A like effect is produced in the warm weather by substituting similar
plugs, but quite dry, having been baked for hours in an oven, for the
purpose of driving out every particle of moisture. These plugs are
hammered into the holes as deeply as they will go, and there left. Even
if there be no rain, the nightly dews make their way into the pores of
the dry wood, and cause it to swell with such irresistible force that
the stone is split with scarcely any manual labour on the part of the
workmen.
* * * * *
YET another plan for cutting hard stones. Some of my readers may be
aware that a singularly ingenious instrument has been invented for
cutting boles in granite and other hard rocks. It is called the Diamond
Drill, because its tip is armed with uncut diamonds.
It is necessary that the diamond should not be cut, as the natural edges
are needed. A glazier’s diamond, for example, is always set as it came
out of the mine. The stories that are told about cutting out panes of
glass with a diamond ring are all absurd. A diamond, when it has once
passed through the hands of the jeweller, cannot cut glass. It can
scratch glass, but not one whit better than a flake of ordinary flint.
[Illustration: BORER OF ŒSTRUS.]
[Illustration: DIAMOND-HEADED BORER.]
It is found that the Diamond Drill works with wondrous rapidity, cutting
away the stone with ease, and suffering scarcely any damage itself. The
tube to the end of which the diamonds are fixed is generally made in
telescopic fashion, so as to allow it to penetrate deeply into the rock,
without the necessity of shifting the machine by which it is turned. I
need hardly say that its rate of speed is very great indeed.
* * * * *
OUR old friend, the Gad-fly, again affords an example of a parallel.
The ovipositor is tubular, telescopic, and furnished at the top with
five little hard, sharp, scaly knobs, which act the same part as the
diamonds of the mining tool. Even the scoop-like shape of the tip, and
the telescopic shaft, are almost identical in both instances.
USEFUL ARTS.
CHAPTER XIII.
TELESCOPIC TUBES.--DIRECT ACTION.--DISTRIBUTION OF
WEIGHT.--TREE-CLIMBING.--THE WHEEL.
Telescopic Tubes, their Structure and Uses.--The Japanese
Fishing-rod.--The Tripod Wheel-bearer and its Telescopic
Structure.--The Rat-tailed Maggot.--Locomotion.--Direct
Action.--The Rocket, the Water Tourniquet, and Electric
Tourniquet.--Cuttle-fish.--The Flying Squids.--The Paper
Nautilus.--Proceedings of newly-hatched Calamaries.--Larva of the
Dragonfly.--Distribution of Weight.--The Snow-shoe, its Structure
and Mode of using it.--The Skidor of Norway.--A formidable Rifle
Corps.--The Mud-patten.--Foot of Duck tribe.--Foot of
Jacana.--Locomotion of Water-gnat.--Tree-climbing.--Mode of
ascending Palm-trees.--The Value of a Hoop.--The “Girt Pupa” and
Butterfly.--Principle of the Wheel.--The primitive Wooden
Wheel.--Spoked Wheels.--Driving Wheel of the Bicycle.--Naturally
spoked Wheel of the Chirodota.
MEANS AND APPLIANCES (_continued_).
We will now treat rather more in detail the two subjects which were
lightly touched upon at the end of the last chapter.
The reader will remember that the diamond-headed borer is made in
telescope form, so as to be adjustable at pleasure. It was also remarked
that the ovipositor of the Gad-fly was made in a similar fashion, so as
to be withdrawn within the body of the insect when not needed, and
protrusible to a considerable extent when the Gad-fly wishes to deposit
her eggs.
As to our modern telescopes and opera-glasses, they are so familiar that
there is little use in describing them, except to say that their
framework consists of a number of tubes of gradually lessening diameter,
the one sliding within the other, so that the instrument can be
lengthened or shortened at will, so as to suit the focus of the
observing eye.
A very ingenious adaptation of the telescopic principle is seen in the
Japanese fishing-rod, which is now tolerably well known. Our own
telescopic rods require to be withdrawn at the butt-end, and then fitted
together in front. But the Japanese rods are so made that, after taking
off the ferrule of the seeming walking-stick, a mere fling of the hand
will send joint after joint flying out, and fixing themselves in regular
succession. So admirably are these rods made, that even blowing into the
butt-end will have the same effect.
* * * * *
ONE of the most perfect, if not the most perfect, example of the
telescopic tube is to be found in the Tripod Wheel-bearer (_Actinurus_),
one of the numerous aquatic Rotifers.
[Illustration: ACTINURUS TAIL, OPEN AND CLOSED (MAGNIFIED).]
[Illustration: TELESCOPE.]
It is not usually so small as the generality of its class, being nearly
one-twentieth of an inch in length, and visible to the unassisted eye,
provided that the owner of the eye in question knows how to use it.
When placed under a microscope of moderate power, the Actinurus is seen
to be built almost wholly upon the telescopic pattern. Only the centre
of the body remains stationary, the two ends being framed on the
principle of the telescopic tube, and capable of being enclosed within
the central portion, just as is the case with the Japanese fishing-rod.
In the illustration the Actinurus is shown in two attitudes. In the
upper figure it is represented as having the fore-part of the body
entirely, and the tail part nearly, withdrawn within the central
portion. The lower figure shows the same specimen with all its
telescopic tubes drawn out to full length.
The creature is perpetually elongating and contracting its body by means
of these tubes, so that a measurement of its length is not easy to
obtain.
A full and interesting description of this curious Rotifer may be found
in Gosse’s “Evenings at the Microscope,” p. 300. The long tails of the
Rat-tailed Maggot, already described under the head of Diving, are good
examples of the drawtube as found in Nature.
LOCOMOTION.--DIRECT ACTION.
The second point which has to be elucidated is that or progress by means
of Direct Action.
[Illustration:
NAUTILUS.
LARVA OF DRAGON-FLY.
ROCKET.
WATER TOURNIQUET.
ELECTRIC TOURNIQUET.]
We have already seen how vessels can be propelled by sail, oar, paddle,
or screw. We have now to consider a mode of progress which requires none
of these things, but which works by means of Direct Action.
Such, for example, is the progress of a Rocket through the air.
The heated gases rush out with tremendous violence, and, by their
pressure, urge the heavy rocket into the air with the rush, roar, and
bang so familiar to all who have witnessed a good display of fireworks.
A rocket in the act of ascent is shown in the uppermost figure of the
accompanying illustration.
Below it is shown the Water Turbine, the principle of which is evident
from the sketch.
From each of the apertures a stream of water is forcibly directed, and,
by its resistance, spins the vessel round and round. There are several
shops in London in which this instrument may be seen at work.
Although in such positions it is necessarily a mere toy, it carries with
it, in common with many other toys, the germs of valuable inventions.
Indeed, there have been attempts to utilise the principle of Direct
Action in the propulsion of vessels, but as yet the mechanical
difficulties have proved practically insuperable, and, although a vessel
has been thus propelled, the expense has been heavier than that of the
paddle or screw, and the speed not nearly so great.
On the right hand of the illustration is another example of Direct
Action, called the Electric Tourniquet.
In the two previously mentioned instruments the motive power is visible,
but in this it is invisible except in the dark.
The principle is exactly the same as in the pocket or water tourniquet;
but, instead of heated air or a stream of water, electricity is used.
The instrument is attached to an electric machine, and fully charged.
The electric fluid rushes out of the points, forces itself against the
air, and so, by its recoil, drives the machine round and round upon its
pivot.
* * * * *
WE will now take two examples of Direct Action as found in Nature.
Perhaps many of my readers have seen the Octopus, and admired the manner
in which it glides through the water, trailing its long arms behind it.
Whence the force comes is not easily seen, and the creature appears to
move almost by volition. In reality, however, it employs Direct Action.
It takes water into the body, and then it ejects it through a tube
called the “siphon” with such force that the animal is propelled
backwards through the water.
Some of the creatures belonging to the Cuttles, and popularly called
Squids, can use such extraordinary powers that they can project
themselves far out of the water. In consequence of this power, they are
sometimes called Flying Squids, and, as they have been known to shoot
themselves completely over the hull of a large ship, they well deserve
the name.
The common Squid of our coasts, which furnishes the so-called
Cuttle-bone, affords us a good example of Direct Action. I once hatched
a number of young Squids from the grape-like eggs, and it was most
curious to see how the little creatures shot about as soon as they
escaped from the egg.
They also utilised the siphon in another way. Poising themselves just
above the sand with which the bottom of the vessel was covered, they
directed a stream of water upon it, and thus formed little cavities into
which they settled like birds into their nests.
The figure represents the Paper Nautilus as it appears while passing
through the water. Just at the base of the tentacles is seen the short
siphon, from which it is pouring the stream of water which drives it
along.
Below the Nautilus is seen the larva of the common Dragonfly. We have,
when treating of the Lazy-tongs, already described the mode in which the
insect takes its prey, and our object could not be served by repetition.
Suffice it to say that the insect is shown in the act of ejecting water,
and so shooting itself along in preparation for seizing prey.
DISTRIBUTION OF WEIGHT.
Being on the subject of locomotion, we will examine a few of the
contrivances by which a man is enabled to pass in safety over soft
substances into which he would otherwise sink.
The first and best-known of these is the Snow-shoe of Northern America.
It is a framework of wood, shaped as shown in the upper figure on the
right-hand side, and strengthened by two cross-bars. The interior of the
“shoe” is filled in with hide thongs arranged much like those of a
racket, and stretched as tightly. The front of the snow-shoe is slightly
turned up, so as to avoid the danger of the point sticking in the snow,
an event which, however, generally happens to a novice.
These instruments are of considerable size, a specimen in my collection
measuring exactly five feet in length, by fifteen inches in width.
Supported on the snow-shoe, the hunter is enabled to glide unhurt over
the deep snow in which he must have sunk without some such aid. He can
thus hunt the bison, the wapiti, or any of the larger animals, being
able to pass rapidly over the surface, while they are laboriously
ploughing their way through the snow-drifts.
[Illustration:
FEET OF DUCKS. SNOW-SHOE.
FOOT OF JACANA. MUD-PATTEN.
WATER-GNAT. SKIDOR.]
It occasionally happens that the snow falls before the shoes are ready.
In this case the hunter is obliged to extemporise snow-shoes by cutting
them out of thin boards.
Several years ago, when snow fell heavily and remained unmelted for many
days, some Canadians, who were visiting England, made quite a sensation
by donning their snow-shoes, and travelling over the snow-clad country.
It was very pretty to see the easy way in which they could shoot down a
hill, and to watch the peculiar gait which is needed by the snow-shoe.
* * * * *
AT the bottom of the illustration is shown a portion of a curious skate
used in Norway, and called Skidor.
These remarkable implements achieve by means of length the task which
the snow-shoe accomplishes by width. They are made of wood, and, though
but a few inches in width, are ten feet or more in length. One is always
a few feet shorter than the other, for the convenience of turning. Much
practice is needed for the management of the Skidors, but, when they are
fairly mastered, they enable their owner to travel at a wonderful pace.
The Norwegian hunter is quite as dependent on his Skidor as the North
American on his Snow-shoe, and uses it for exactly the same purpose. A
corps of these hunters has been organized for war, and very formidable
they were, hanging on the skirts of the enemy, and giving him no rest,
day or night. They never came within fifty yards of each other, so that
even cannon were useless; and, as soon as they thought that they were
endangered, they dispersed in all directions, only to reunite and swoop
down again on the enemy at the first opportunity.
* * * * *
THE central figure represents the Mud-patten, which, as its name
implies, plays the same part towards mud that the snow-shoe and skidor
do to the snow. Like them, also, it is not easy to manage; and a novice
is tolerably certain to drive the front of the patten into the mud, and
so get an awkward and not aromatic fall.
This patten, which is merely a square piece of board attached to the
foot, is in use on many of our coasts where the ebbing tide runs out to
a great distance, leaving a vast expanse of soft mud. Like the skidor
and the snow-shoe, it is mostly used by sportsmen, especially in the
winter, when wild-duck shooting sets in.
Aided by the pattens, a sportsman can travel for miles over mud that
would otherwise swallow him up, shoot his birds, and secure them when
fallen. While engaged in winter shooting on the Medway, we have often
lost birds because they fell beyond a deep mud-bank, and we had no means
of crossing it.
* * * * *
ON the left hand of the illustration are some natural parallels of
these artificial aids. The two upper figures represent two forms of
webbed feet, and the analogy between them and the snow-shoe and
mud-patten is too obvious to need explanation.
In the centre is the foot of the Jacana, an Asiatic bird. Its foot may
well be taken as the analogue of the skidor, length taking the place of
breadth, and enabling the weight to be distributed over a large surface.
This bird finds its food in rivers and lakes, and, by reason of its
enormously long toes, can walk with safety over slight floating
vegetation, which would give way at once under the tread of any bird
except a Jacana. Very good representations of this bird are to be seen
in Japanese works of art, especially those which are mounted as screens.
Even the peculiar gait of the bird is given with marvellous truth.
The last figure represents the common Water-gnat (_Gerris_), which may
be seen in almost any piece of fresh water, however small. Ponds that
are open to the south, and sheltered from the north wind, are its
favourite localities.
It is a carnivorous being, feeding almost wholly on insects that fall
into the water. In order to capture them, it runs rapidly over the
surface of the water, the long slender legs distributing its weight over
a large surface, and so keeping it from sinking. Only the last two pairs
of legs are employed for this purpose, the first pair being held in
front of the body, and used for the purpose of capturing prey.
TREE-CLIMBING.
Another curious aid to locomotion is shown in the accompanying
illustration.
In many parts of the world, where the cocoa-nut palm grows, the natives
have invented a simple, but ingenious, plan for ascending the tall,
curved stem. Such a thing as an upright palm-tree is unknown, and
consequently the ascent of the branchless stem is not an easy task
without artificial assistance.
When I treated of Warfare and the different modes of scaling walls, the
climbing-spur was casually mentioned. The implement of the palm-climber,
however, is simpler and more effective, as it leaves both hands at
liberty when desired.
The man cuts a long piece of one of the tough and almost unbreakable
creepers which festoon the trees of tropical climes. He passes it round
the trunk which he wishes to climb, and fastens the ends firmly
together, so as to form a large loose hoop. He then passes the hoop over
his head, until it presses against his back, as seen in the
illustration, and serves to support him as he leans against it.
[Illustration: GIRT PUPA AND BUTTERFLY.]
[Illustration: CLIMBING PALM-TREE.]
Taking the hoop by the two sides, he lifts it up the trunk as far as he
can, places the soles of his feet against the tree, and so walks up it,
hitching the hoop upwards at every step. When he has reached the top of
the tree, he supports himself entirely by the hoop, while his hands are
at liberty to be used in getting the cocoa-nuts.
* * * * *
IN the insect world there are many examples of support being given by a
belt passing round the body.
Among the Butterflies, for example, there are many which, in their pupal
stage of existence, are attached to upright stems. They are fixed to the
stem by a few threads at the tail, answering to the feet of the
tree-climber, while the body is kept in position by a stout silken
thread passed loosely round it.
The illustration represents the pupa of the common Swallow-tailed
Butterfly, while in the centre is the same insect in the perfect state
as it appears when resting. It really seems as if the ancient habit of
the pupa had been remembered by the perfect insect, the long ends of the
hinder wings taking the place of the pupal tail, and the legs that of
the belt.
THE WHEEL.
Yet another aid to locomotion is found in the WHEEL, a contrivance for
diminishing friction.
[Illustration: WHEEL-SPICULE OF CHIBODOTA.]
[Illustration: CART-WHEEL.]
When man first learnt that heavier weights could be dragged than
carried, he simply placed them on flat boards to which ropes were
attached. The next step was necessarily the invention of the sledge, the
burden resting on two parallel runners, the ends of which were slightly
curved so as to prevent them from hitching against any small
obstruction. In some countries--such, for example, as in
Esquimaux-land--the sledge is the only vehicle practicable, and even
Europeans, when they visit that country, are fain to adopt the sledge if
they would live.
But, in more temperate zones, the Wheel is paramount. In its earlier
stages the wheel was a very simple business. It was simply a section of,
a tree-trunk, dubbed roughly round, and with a hole in the centre,
through which the axle passed. Such wheels are still in existence in
many parts of Europe; and, owing to the want of regularity of outline in
the circumference, and the utter absence of grease, the wheels keep up a
continuous shriek, almost deafening to those who are unused to it, but
perfectly unheeded by those who own or drive the vehicle.
The next improvement was to make the circumference of the wheel as
perfectly circular as the art of man could devise, and, instead of
having the wheel solid, to fill up its interior with spokes, thus
gaining lightness and strength at the same time.
Of all locomotive wheels, I suppose that the modern Bicycle affords the
best example. The driving wheel is larger than the hind wheel of an
ordinary coach, and yet the spokes are not nearly so thick as the
porcupine quill with which this account is written.
If we look at the ancient sculptures and paintings of Egypt and Assyria,
as preserved in the British Museum, we shall see that either kind of
wheel was used according to the work which it had to do. The solid,
uneven, squeaking, wooden wheel was devoted to agriculture, while the
light, spoked wheel was sacred either to warfare or hunting.
Let us hope that in the two latter cases some modicum of grease might
have been used, as the outcries of tortured and unlubricated machinery
are enough to drive away all wild beasts which come within the range of
its complaints, while the nervous system of hunter or warrior must have
been seriously damaged by it.
* * * * *
EVEN in such a structure as the spoked Wheel, Nature has anticipated
Man.
My readers may remember that, when treating of nautical matters, I
mentioned the singular anchor-shaped spicules that are found upon one of
the sea-slugs, called Synapta.
There is another group of these creatures inhabiting the Mediterranean,
in which the skin-spicules take a different form. Like those of the
Synapta, they are too small and translucent to be seen without the aid
of the microscope and carefully adjusted light. But, just as the
spicules of the Synapta resemble the ancient anchor, so do those of the
Chirodota resemble the ancient wheel, the similitude being in both cases
absolutely startling.
Not only that, but, as all readers must be aware, if they have studied
practical mechanics, there are many machines which are toothed on the
inner, and not the outer, side of the circumference. Here, in the
Chirodota, the inner toothing is manifest.
What purpose it serves we know not. The Chirodota’s wheels (of which
there are thousands) never revolve, neither do the anchors of the
Synapta hold the ground. Yet the very fact that such exceedingly minute
objects should be so carefully constructed tells us at once that they
must have some important purpose to serve, though at present that
purpose is a mystery which no one has attempted to solve.
I have little doubt that when the hour and the man arrive, as arrive
they surely will, we shall find in these tiny and almost unrecognised
spicules the keys to treasures of wisdom which at present have been
opened to no human being.
The whole history of the progress of the human race shows that facts
have been allowed to accumulate, fought about, and turned in all
directions, before the generaliser comes who pierces to the heart of
everything, reduces apparent discrepancies to harmony, and usually is
rewarded by finding some one else assume the credit of his discoveries,
and receive all the honours and emoluments.
USEFUL ARTS
CHAPTER XIV.
Paper and its many Uses.--The Egyptian Papyrus.--India
Paper.--China and its Manufactories.--Materials of which Paper is
made.--Annual Consumption of Material.--The “Water Mark.”--Nature’s
Papers.--Wasps and Hornets.--The common Wasp, and the various
Materials of its Nest.--Utilisation of
Material.--Papier-mâché.--Printing.--Nature-printing.--Method and
Results of the Process.--Use of the Electrotype.--“Facing” the
Copper Plates with hard Metal.--The Coal Mine and its
Nature-printing.--Stippling, its Use and Abuse.--The Line and the
Dot.--Modification of the Dot.--Flower-petals.--The
Pelargonium.--Plaster Castings.--Stereotyping and
Electrotyping.--Modern Method of taking Plaster Casts.--The
Principle of Corrugation.--Flower-pot Covers.--Iron Buildings.--The
Polistes and its Corrugated Dwellings.
ART.
We will now touch lightly on the subject of Art.
In the present day one of the most indispensable accessories to art is
Paper.
It is a curious fact that we have no records as to the time when paper
was first invented. The Egyptian papyrus we do not consider, as it was
not paper in our sense of the word, although we have retained the name.
Paper is a vegetable fibre carefully disintegrated, made into a pulp
with water, and then dried in thin sheets. As is the case with many
arts, China seems to have taken the lead in paper manufacture, and we
are even now indebted to that country for the “India Paper” on which the
finest proofs of engravings are taken. This paper is made from the inner
bark of the bamboo. “Rice Paper,” so called, is not paper at all, but
only a kind of pith cut spirally, and flattened by pressure.
There is scarcely any vegetable fibre of which paper cannot be made, and
various plants have been suggested for this purpose, such as the
stinging-nettle, cabbage-stalks, hop-bines, the waste of sugar-cane,
sawdust, &c. Straw has already been successfully used, and so has
Esparto grass.
Some years ago, when there was a scarcity of material for paper-making,
the well-known Grass-wrack of our shores (_Zostera marina_) was brought
into partial use. I believe, however, that the experiment was not a
successful one. The Chinese make their paper of bamboo, macerating and
pounding it until it is reduced to a pulp, and then shaken into fibres
in a mould.
[Illustration:
NEST OF HORNET. PAPER-MAKING.
NEST OF TREE-WASP. PAPER.]
With us, white paper, such as is used by the writer, printer, or artist,
is made almost exclusively of cotton or linen rags. Upwards of a hundred
and twenty thousand tons weight of rags are annually consumed in this
country for the manufacture of paper. After being bleached, they are
torn and ground into a pulp, which is then handed over to the actual
maker.
The illustration represents paper-making by hand, a process which is now
rarely used, except for special kinds of paper. Omitting technical
details, the mode of paper-making by hand is as follows:--The pulp being
prepared, the workman takes a “mould,” _i.e._ a frame with a bottom of
closely woven wire. Having put into the mould a sufficient quantity of
pulp, he shakes the mould so as to spread the pulp evenly over the
surface. The water runs away between the wires, the sheet of pulp is
transferred to a piece of felt, and when it is dry it becomes paper. If
a sheet of ordinary note-paper be held up to the light, the marks of the
wires are plainly perceptible. The so-called “water-mark” is due to
wires twisted into the requisite shape.
The Chinese workman makes his paper exactly on the same principle, but
the bottom of his mould is made of bulrushes instead of wires.
As for machine-made paper, the process seems absolutely magical. Endless
bands of felt and wire are substituted for the hand frames, and, the
pulp being poured in at one end, the finished paper is poured out at the
other, and self-wound on rollers. Without any exaggeration, paper is now
made by the mile, the only limit to its length being the size of the
rolls.
* * * * *
WHEN I mention Paper-making in the world of Nature, many of my readers
will at once know that I am about to refer to the Wasp tribe.
These insects were paper-makers long before even the Chinese had
invented the art, and, so exactly similar is the mode of action, that
man might well have copied from the insect.
The Wasp gnaws a bundle of vegetable fibres, mostly of wood, sound or
decaying, according to the species. It masticates them until it has
reduced them to a pulp, and then, by means of its jaws, spreads the pulp
into sheets of various shapes and sizes.
With some of the pulp it forms hexagonal cells like those of the bee,
and with some it makes the roof-like covering which defends the cells.
Not only that, but it can make a sort of papier-mâché, which it uses for
the flooring, if we may so call it, of the different strata of cells,
and for the pillars which bind them together.
Like our own paper manufacturers, it is economic of material, will
re-masticate any superabundant paper, and is only too glad if it can get
hold of any paper made by man. I have seen a wasps’ nest which was made
entirely from the empty blue and white cartridges that were thrown away
by soldiers.
Then there is as much difference in the papers made by wasps as in those
made by man. In this country all wasps’ nests are made of very fragile
material, but in South America there are some wasps which make the
external covering of their nests as hard and white as the stiff
cardboard employed by artists.
* * * * *
HAVING now got our paper, we will glance at one or two modes of using it
for Art. Papier-mâché has already been mentioned, and it is worthy of
notice that there are now in existence many decorated ceilings which are
made of this material, on account of its great strength and its
non-liability to fire.
[Illustration: FERNS IN COAL.]
[Illustration: NATURE-PRINTING.]
The first invention which we shall notice is that which is known by the
name of Nature-printing, and which has been so successful in
transferring to paper an exact representation of vegetable foliage.
One simple tolerably efficacious mode of Nature-printing has long been
known. A piece of paper being rubbed with lamp-black and oil, the leaf
was laid upon it and gently rubbed, so as to transfer the lamp-black to
the nervures. It was then laid on a sheet of white paper, and again
rubbed, when an impression of the leaf was left upon the paper.
The present system of Nature-printing is far in advance of this rather
rude method, and amounts to an exact reproduction of the plant, not only
in form and detail, but in colour.
In order to illustrate this beautiful process, I cannot do better than
transfer to these pages the following account of Nature-printing as
given in Ure’s “Dictionary of Arts,” &c. It is an abstract of a lecture
delivered by Mr. H. Bradbury at the Royal Institution.
“Nature-printing is the name given to a technical process for obtaining
printed reproductions of plants and other objects upon paper, in a
manner so truthful, that only a close inspection reveals the fact of
their being copies; and so distinctly sensible even to touch are the
impressions, that it is difficult to persuade those unacquainted with
the manipulation that they are an emanation of the printing-press.
“The distinguishing feature of the process consists, first, in
impressing natural objects--such as plants, mosses, seaweeds, and
feathers--into plates of metal, causing, as it were, the objects to
engrave themselves by pressure; secondly, in being able to take such
casts or copies of the impressed plates as can be printed from at the
ordinary copper-plate press.
“This secures, in the case of a plant, on the one hand, a perfect
representation of its characteristic outline, of some of the other
external marks by which it is known, and even in some measure of its
structure, as in the venation of ferns and the ribs of the leaves of
flowering plants; and, on the other, affords the means of multiplying
copies in a quick and easy manner, at a trifling expense compared with
the result, and to an unlimited extent.
“The great defect of all pictorial representations of botanical figures
has consisted in the inability of art to represent faithfully those
minute peculiarities by which natural objects are often best
distinguished. Nature-printing has therefore come to the aid of this
branch of science in particular, whilst its future development promises
facilities for copying other objects of nature, the reproduction of
which is not within the province of the human hand to execute; and even
if it were possible, it would involve an amount of labour scarcely
commensurate with the results.
“Possessing the advantages of rapid and economic production, the means
of unlimited multiplication, and, above all, unsurpassable resemblance
to the original, nature-printing is calculated to assist much in
facilitating not only the first-sight recognition of many objects in
natural history, but in supplying the detailed evidences of
identification, which must prove of essential value to botanical science
in particular.”
Many plans have been tried with only partial success, but that which is
now in operation produces the most wonderful results. The plants are
laid upon sheets of lead, and then passed through rollers, so as to
leave an impression in the soft metal. The electrotype then comes into
play, exact copies of the impression being taken by it. As the face of
the electrotyped plate is covered with a slight deposit of some hard
metal, usually nickel, a great number of copies can be taken without
damaging the plate.
* * * * *
A WONDERFULLY exact parallel to Nature-printing is seen in almost every
coal bed. In the coal are found impressions of various leaves, mostly
ferns, and so exact are they, that the different species have been
determined and named with as much accuracy as if, instead of mere
impressions, they had been the fern-leaves themselves.
Indeed, if it were needed, it would be perfectly easy to take
electrotype plates from these impressions, and to treat them in exactly
the same manner as those obtained in the way which has already been
described.
STIPPLING.
We now come to another branch of Art, namely, the production of shadow
in an engraving by means of Stippling, i.e. the insertion of dots
instead of lines. At one time the Stipple was in great favour. Then it
was almost wholly abandoned in favour of the line, and now it is much
used in conjunction with the line, especially for the delicate shading
of flesh tints, such as faces, female arms, &c.
In the illustration a little stippling of a cheek is shown, the dots
being purposely exaggerated.
A singularly beautiful modification of the Stipple is now in use. When
the engraver wishes for exceptional softness of shading, he does not
content himself with mere dots, but, with the aid of his
magnifying-glass, converts each dot into a tiny star with three or more
rays. Thus the dots seem to melt into each other, and the requisite
softness is obtained.
A very good example of this star-stipple is seen in the well-known print
called “Coming of Age.” If the face and neck of the girl in the
foreground be examined with a magnifying-glass, the apparent dots will
be seen to be stars, so beautifully arranged that the projecting rays of
one fuse themselves, so to speak, with, those of the surrounding stars,
as is shown in the illustration.
* * * * *
WHETHER the engraver who hit upon this singularly effective plan took it
from Nature, I cannot say, but he well might have done so, had he
examined the petal of a flower through a good microscope. We all know
the peculiar rich softness of a petal, and how our very best floral
artists feel the impossibility of transferring it to paper.
[Illustration: STIPPLING.]
[Illustration: PETAL OF GERANIUM.]
The real reason for this special beauty lies in the star-stippling of
the petal. The whole surface of the petal is covered with multitudinous
projections, which are, in fact, undeveloped hairs. These projections
are wrinkled down the sides, and so, when viewed from above, they
present the curious star-like appearance shown on the right hand of the
illustration.
The drawing is taken from a petal of Pelargonium prepared by myself.
There is yet one point in the petal which the star-stipple has not
touched, and probably cannot touch. I mean the slight projection of the
stipple-hairs, which give an effect of light and shade as well as mere
flat softness.
PLASTER CASTS.
We have already mentioned the electrotype, and may now come to a branch
of art which is much associated with it, namely, the Stereotype.
As many of my readers may know, types are very valuable articles, and
must not be wasted. If, therefore, a book should be thought likely to
have a steady sale, much of its value would be lost if the types were
kept standing, inasmuch as they could not be used for any other work.
In such cases the Stereotype is employed. Omitting minute details, the
process is as follows:--
[Illustration: SHELL-CAST IN CHALK.]
[Illustration: CAST IN PLASTER OF PARIS.]
The type, ready set up, is carefully oiled. Plaster of Paris mixed with
water is then poured into a shallow trough, and the type pressed into
it. In a short time the plaster hardens, and the type is withdrawn. The
plaster mould is then baked, to drive off all moisture, and type metal
is poured into it. Thus a solid mass is procured, instead of a number of
separate pieces, so that there is no danger of disturbance, and the
whole block can be multiplied _ad libitum_ if needed. This process sets
free the types, which can be broken up and used again.
The ordinary method of taking plaster casts is nearly the same as that
which has been described. The object to be cast is oiled, and plaster of
Paris carefully applied to it. When it is “set,” the plaster “mould” is
removed and dried. The process is then reversed, the interior of the
mould being oiled, and plaster poured into it, so as to produce an exact
reproduction of the original.
* * * * *
IN Nature we have almost exactly the same process, although it is
necessarily conducted in a much slower manner.
All who have tried their hand at practical geology must be aware of the
multitudinous casts of perished beings which are found in various
strata. Sometimes the casts are those of vegetables, the original
material having been decomposed, and stony matter taken its place.
Sometimes there are casts of fishes or echini, while shells, and even
insects, are found to have been cast almost as perfectly as could be
done with plaster of Paris at the present day.
As might be anticipated, the chalk deposits are peculiarly rich in these
casts, the fine particles of the chalk taking the place of the plaster
of Paris.
In the illustrations are shown examples of casting in Art and Nature. On
the right hand is a cast of fruit and leaves, which may afterwards be
reproduced in plaster, wax, papier-mâché, or electrotype. On the left is
shown one of the shells so common in the chalk, the upper figure
representing the shell itself, and the lower the mould that has been
formed around it.
CORRUGATED IRON.
We have already seen that the Wasps are paper-makers. We may now see how
some of the Wasps have anticipated a valuable invention of man, namely,
the principle of corrugation, whereby a thin plate gains strength.
[Illustration: NESTS OF POLISTES.]
[Illustration: CORRUGATED IRON.]
Even a sheet of paper gains great strength by corrugation, as is seen in
those paper covers which are so much in use for the decoration, or
rather the concealment, of flower-pots. But the best example that can be
given of this principle is the Corrugated Iron, which has come so much
into use for temporary buildings, such as schools, places of worship,
reading-rooms, &c. It is very light and very strong, and can be used
either for roof or walls with equal success.
* * * * *
BY means of certain wasps belonging to the genus Polistes, Nature
produces corrugated dwellings, which are made of very thin materials,
but which are marvellously strong in proportion to their weight.
The insects belonging to this genus are all exotic, but are spread over
a very large surface of the earth.
So strong are the nests made by some of these species, that they need no
external covering, the corrugated paper supplying at the same time
strength and warmth, the latter element being furnished by the air which
is entangled between the corrugations.
There are many species of Polistes, mostly belonging to Australasia and
tropical America, the latter displaying the greatest variety of form and
structure in the nest.
USEFUL ARTS.
CHAPTER XV.
Electricity, Magnetism, and Galvanism mutually convertible.--The
Force co-extensive with Nature.--Uses of Thunder-storms.--Languor
from Want of Electricity.--Frictional and Voltaic
Electricity.--Origin of the Name.--Structure of the Voltaic
Pile.--A simple Example of the Pile.--Nerves of a Frog’s Leg.--The
Electric Shock, and how to produce it.--The Electric Jar and
Battery.--Animal Electricity.--The Torpedo and Electric
Eel.--Structure of the Electric Apparatus.--The Electric Spark
obtained from both Fishes.--Channels of Electricity in the
Body.--The Will and the Muscles.--Electricity the conducting
Agent.--The Human Body permeated by Nerves.--Telegraph Wires and
the Nervous System.--Lightning and the Electric Spark.--The
Electric Light and its Power.--The Fire-fly, the Glow-worm, and the
luminous Inhabitants of the Sea.--Magnetism and Diamagnetism.--The
Electric Telegraph and the Compass.--The Principle identical in
both Instruments.
ELECTRICITY AND MAGNETISM.
It has long been known that Electricity, Galvanism, and Magnetism are
but different manifestations of the same force, and that one can be
converted into the other at will. It is also known that this wonderful
and most important principle lies latent in everything, and only needs
the proper machinery to evoke it.
The few following illustrations are intended to show its prevalence in
Nature, and that human art does not create, but only makes manifest a
power that exists, but lies latent until called forth.
Without going into details, which would occupy the whole of such a
volume as this, I may mention that Electricity saturates all the
material creation, and that even man himself is not only a reservoir of
electricity, but that he feels positively ill if the normal amount be
not supplied.
Take, for example, the hours that precede a thunder-storm. We feel
languid and depressed. We cannot bring our thoughts together. We are
almost incapable even of bodily labour. The reason is, that the portion
of the earth on which we live has parted with some of its electricity,
and has drawn it out of our bodies.
Then comes the welcome thunder-storm; clouds overcharged with
electricity come to restore the balance. The lightning flashes from the
clouds to the earth as soon as they are near enough; the rain falls,
carrying with it stores of silent electricity; and in an hour or two all
seems changed.
The air, which hitherto seemed to afford no nourishment to the lungs, is
bracing and invigorating. The nervous system recovers its tension, and
the brain can act without a painful effect. All Nature seems to put on a
different aspect, and brightness and vigour take the place of dulness
and languor.
[Illustration: GALVANISING A FROG’S LEG.]
[Illustration: VOLTAIC PILE.]
By a strange coincidence, there is just such a lack of electricity as I
am writing, and the barometer has rapidly sunk to such a degree that a
storm seems inevitable.
One of the chief difficulties in dealing with such a subject as this is
to know where to begin. We will, however, do our best to take a general
view of it, without going into details.
Many centuries ago it was well known that amber, if rubbed with a dry
cloth, would first attract, and then repel, various small and light
substances. Indeed, the Greek word for amber, namely, _Elektron_, has
given its name to the modern science of Electricity. Many other
substances, such as glass, sealing-wax, &c., possess the same property.
This frictional electricity is but transient, the electric fluid, if we
may be allowed to use the term, being driven out by main force from the
material in which it was latent, just as fire is procured by the
friction of two dry sticks. There is, however, a form of Electricity
called Galvanism, from its discoverer, Galvani, who, somewhere about
1790, discovered that the limbs of a dead frog might be excited to
action by electricity applied to the nerves.
Afterwards, Volta of Pavia, from whom the Voltaic Pile is named, took up
Galvani’s discoveries, and produced electricity without friction, by the
contact of differently conducting substances.
The right-hand figure represents the Voltaic Pile. It is composed of a
series of plates arranged in the following manner--Zinc, Silver, and
Cloth, the whole being moistened with diluted acid. Copper will answer
the purpose nearly as well as silver, and is not so costly. A very
simple mode of demonstrating the presence of electricity is by taking a
piece of zinc and a silver coin, and placing one below and the other
above the tongue. If the two be then brought together, a very peculiar
taste is perceived, and a sudden flash of light seems to pass across the
eyes.
The illustration represents on the right hand the Voltaic Pile as at
present made, and on the left are the two hind-legs of a frog, with the
upper part of the nerves made bare for the purpose of experimenting. The
dotted lines show the extent of the movements of the leg when the
galvanic current is passed through the nerves.
* * * * *
NOW we come to a plan whereby electricity can be accumulated, or locked
up, so to speak, and be discharged at once with a definite shock instead
of being poured away by degrees. This can be done in many ways, the most
common being that which is known by the name of the Electric Jar. It is
a glass vessel coated within and without with tin-foil, and having a
metal rod passing through the cork in such a way that while the lower
end is in contact with the inner coating of tin-foil, the other end is
guarded by a ball.
Electricity is now poured into the interior of the jar, and, when
contact is made between the inner and outer coatings, a sudden discharge
takes place. If a number of persons hold each other’s hands, and those
who form the two extremities touch the outer coating and the ball which
communicates with the inner coating, a sharp discharge is at once made,
passing through all the bodies, and inflicting a smart shock, especially
at the elbows.
Similar effects can be produced with the Voltaic Battery, but, as that
instrument has already been figured, the Electric Jar has been selected.
Of course any number of such jars can be connected together, and the
shock will be proportionately increased in intensity.
* * * * *
IN Nature we have several-parallels. Putting aside the obvious one of a
lightning-flash, which has already been mentioned, we pass to two
remarkable examples of the capability of animal structure to produce
electricity, to store it up, so to speak, and discharge it at will. Both
these creatures are fishes, one belonging to the Skates or Rays, and the
other to the Eels.
[Illustration:
TORPEDO.
ELECTRIC EEL.
ELECTRIC BATTERY.]
The upper figure on the left-hand side of the illustration represents
the Torpedo, sometimes called the Cramp-fish, Numb-fish, or Electric
Ray. Fortunately for us, it is but seldom found on our coasts, but it is
tolerably common in the warmer parts of the world.
The electric organ in this fish is double, and so large that its shape
can easily be recognised even through the skin. It is made up of a vast
number of discs arranged upon each other in columns like the metallic
portions of the Voltaic Pile, and separated from each other by delicate
membranes, which take the place of the cloth. When I mention that more
than eleven hundred columns have been found in a single Torpedo, and
that each column contains several hundred discs, it may be imagined that
the shock which such a creature can give must be a very powerful one.
The object of this power seems to be analogous to that of the venomous
serpent, _i.e._ to enable the creature to secure its prey by either
killing it or rendering it temporarily insensible by an electric shock.
As if to show that the delivery of the shock is achieved by an exertion
of will, observers have noticed that just before the shock is delivered,
the eyes are depressed in the head like those of a toad when swallowing
a large insect.
* * * * *
A STILL more powerfully electric animal is the Electric Eel of Southern
America. It sometimes attains a length of six feet, and its electric
organs are four times as proportionately large as those of the torpedo.
There is no doubt as to the object of the electric power of this eel, as
I have often seen it kill fish, and then eat them.
When about to deliver its shock, it curves its body towards the intended
victim, stiffens itself, and with a sort of shudder the electric fluid
is emitted. The fish at which it is aimed never seems to escape, but,
simultaneously with the shudder on the part of the Electric Eel, turns
on its back and lies motionless until it is picked up by its destroyer.
Neither the Torpedo nor the Electric Eel has unlimited stores of
electricity. If irritated into delivering repeated shocks, each
discharge is less powerful than its predecessor, until at last the
creature is almost wholly powerless, and must rest and recruit itself
before it can lay up fresh stores of the electric fluid.
I may add that the electric spark has been obtained from both these
fishes. It was only a small spark, but in such experiments a small spark
is as satisfactory as a large one.
* * * * *
WHAT are the channels by which the electric fluid is transmitted through
our bodies?
They are the nerves, which convey from and to the brain a subtle fluid,
if it may be so called, just as the arteries and veins convey blood to
and from the heart. If any of these nerves be electrified, even after
the death of the animal, or after the separation of a limb from the
body, muscular movements are induced, and the limb moves as if instinct
with life.
Without these nerves we should be unable to feel the severest shock, but
they permeate the body so completely, that not a part of the skin can be
pricked without a nerve being wounded.
It is by means of these conductors that the will is made to act upon the
limbs. The mind, for example, desires the legs to walk, and they do so,
the order being transmitted to them through the nerves.
As a rule, we are unconscious of this process. But, when paralysis takes
place, and the nerves refuse to perform their functions, the will is
absolutely useless, and, however desirous a man may be of walking, he
cannot move a step if the nerves of his legs are paralyzed. In cases
where the paralysis comes on slowly and in detail, the patient mostly
becomes conscious of the part played by the nerves, and feels that his
will can to a certain degree rouse the expiring powers of the nerve
fluid.
This in its turn is but the conductor for another and infinitely more
subtle fluid, of which our space will not allow us to treat, but which
forms the connecting link between body and spirit. Perhaps some of my
readers may have seen those curious preparations of the human form, when
the arteries have been injected with red wax, and the veins with blue
wax, and then the fleshy portions dissolved away by chemical means.
The result is a perfect human form, and even to the very tips of the
fingers and toes the blood-vessels follow the contour of the body. Did
we have means of injecting the nervous system, we should arrive at
similar results, except that the nerves would be found infinitely more
intricate than the veins and arteries. Thus a human being is a series of
human forms, interwoven with each other, and mutually dependent on each
other.
* * * * *
IT is curious to see how the great discoveries of modern days have but
copied Nature.
Take, for example, the network of telegraphic wires which is day by day
spreading itself over the surface of the earth, and the parallel will
at once be visible. Just as the brain transmits its message to the limbs
by means of the nerves, so does the same brain transmit its message
through thousands of miles, by utilising the wires which are but the
rough and coarse imitations of the wonderful nervous system of the human
frame.
* * * * *
THE illustration shows the parallelism as well as can be done by a mere
chart.
[Illustration: NERVES.]
[Illustration: TELEGRAPHIC WIRES.]
On the left-hand side is shown the manner in which a nerve-group is
distributed to different parts of the body. On the right the railway
telegraph wires are seen, and, as the reader will probably remember,
branch wires are carried into the signal boxes, just as branch nerves
are carried to the most distant parts of the body.
* * * * *
I HAVE already mentioned the Electric Spark, and that it is, in fact, a
miniature lightning-flash, the little crackling report being a miniature
thunder-clap. It can be produced by frictional electricity, or by the
voltaic pile in its many variations, or by animal substances alone, as
in the case of the torpedo and electric eel.
We now come to a modification of the spark, whereby a continuous current
of electricity is sent through two charcoal points, and inflames them
with such intensity that the eye cannot look upon its dazzling
whiteness. There is none of the yellowness about it which is so great a
drawback to our artificial lights, whether they be gas, candle, or lamp,
and which makes ladies’ dresses that are really beautiful by day look
dull and almost ugly by night.
It is wonderful to see how the Electric Light kills all other lights.
The brightest gas becomes dull, and its shadow is thrown on the wall
which it formerly illuminated, and the most delicate tints of silks and
satins suddenly display themselves in the blinding whiteness of the
Electric Light.
At present it is too costly to be brought into common use, but its
intensity is so great that serious ideas have been formed of dispensing
with street lamps altogether, and illuminating towns with a few electric
lamps placed at a considerable height, and having their beams reflected
downwards.
[Illustration:
LIGHTNING.
FIRE-FLY.
GLOW-WORM.
ELECTRIC LIGHT.]
London is thought to be a specially fit subject for this mode of
lighting, as the electric beams can pierce the fogs which the gas-lamp
only augments, and give the traveller some hope of finding his way
through the most familiar streets.
* * * * *
IN the illustration the right-hand figure represents the Electric Light
as at present in use. The upper portion of the left-hand side represents
the forked lightning, whose dazzling whiteness is so familiar to us,
even in the noon of a summer’s day.
Below are shown the Fire-fly of warm climates, and the Glow-worm, which,
in our comparatively cool country, cheers the summer evenings with its
pale lamp. As to the source of this mysterious light, which burns
without producing heat sufficient to be recognised by our most delicate
instruments, we know but little.
There are instruments so infinitely more sensitive than the best
thermometer, that they will record instantaneously an increase of heat
if a human being passes in front of them, though at several yards’
distance. Yet no effect is produced on them by any of the Fire-flies or
the Glow-worm. The spectroscope itself gives little or no information,
the spectrum of the light being without bands or bars, and being what is
technically called a “continuous” spectrum.
Last year I tried numbers of Glow-worms with the spectroscope, and
always with the same result. I never saw the Fire-flies alive, but, no
matter what may be the colour of the light, the spectrum, whether of the
Glow-worm or any of the Fire-flies, seems to be always continuous, and
so to give but little information as to its source.
There appears, however, to be little doubt that animal electricity is
the real cause of this curious phenomenon, and that the force which is
expended in the torpedo and electric eel, in giving shocks accompanied
by slight electric sparks, may develop itself in these insects by
producing a continuous light. And just as the electric fishes can emit
or withhold the shock as they please, so can the Fire-flies and
Glow-worms give out or retain the light by which they are so well known.
Then we come to the multitudinous luminous inhabitants of the sea,
which, as many of my readers have probably seen, convert the waves into
rolling masses of living fire.
MAGNETISM.
Now we come to another condition of electrical force, called MAGNETISM.
One form of it is strongly developed in the Loadstone, an ore of iron.
This ore has the property of turning east and west when suspended
freely, it attracts any object made of iron, and can communicate its
powers to iron by merely stroking it. There is in the Museum at Oxford a
splendid specimen of the Loadstone, which has imparted its virtues to
thousands of iron magnets, and has lost none of its virtues by so doing.
All bodies are now known to be magnetic in some way or other. Several,
such as iron, nickel, and one or two other metals, turn north and south
when suspended on a pivot, but the great bulk of other bodies turn east
and west, and are called Diamagnetics.
As we all know, the property of turning north and south has been
utilised in the Compass, without which modern science would be
paralyzed, and travel rendered impossible.
[Illustration: LOADSTONE.]
[Illustration: COMPASS.]
It is worthy of notice that although the magnetic needle of the compass
turns to the north, it does not do so because it is attracted by the
north pole, but because it is repelled from the east and west.
We have long known that if a current of electricity be sent round a
magnetic needle, the latter at once turns at right angles to it. On this
principle depends the Electric Telegraph. When communication is made by
using the handles, a current of electricity is sent round the needles,
and causes them to turn at right angles until stopped by a little ivory
pin, which prevents them from overshooting themselves.
There is a perpetual stream of electricity passing over the earth from
east to west, and in consequence all magnetic bodies are forced to turn
at right angles, just as is the case with the magnetic needle.
USEFUL ARTS.
CHAPTER XVI.
TILLAGE.--DRAINAGE.--SPIRAL PRINCIPLE.--CENTRIFUGAL FORCE.
Systems of cultivating Ground.--The Fallow System.--Manuring the
Ground.--Custom of China.--Nature’s Abhorrence of Waste.--What
becomes of Dead Animals.--Burying-beetles.--The Scarabæus-beetles
and their Work.--Drainage _versus_ Sewage.--Clay Soils and
Drains.--The Mole, the Earth-worm, Rats, Mice, and Rabbits.--The
Flexible Drain and the Lobster’s Tail.--The Turbine Pump and the
Ascidian.--The Spiral Principle.--The Smoke-jack, Kite, and Wings
of Birds.--Centrifugal Force.--Revolution of Planets.--The
“Governor” of the Steam-engine.--The Sling, Amentum, and Mop.--The
Gyroscope, the Bicycle, and the Hoop.
Several times, in the course of this work, we have touched upon man’s
dealings with the earth, such as mining and tunnelling. We will now take
another side of the same question, and, in connection with Tillage,
consider Drainage, whereby superabundant moisture is removed from the
earth, and Manuring, whereby the exhausted soil is renovated.
We will take this subject first.
It has long been known that it is impossible to get more out of the
ground than exists in it, and that when the soil has been so worked as
to become unproductive, there are only two remedies. The one is to allow
the ground to remain uncultivated for a time. It must be ploughed in
deeply, as if it were to be sown with a crop, and must be left to
recruit itself from the air. This is the now abandoned “fallow” system,
which used to be in full operation when I was a child.
As, however, population increased, and with it the perpetually
increasing demand for food, land was found to be too precious to be
allowed to lie fallow and idle. Then came the system of rotation of
crops, potato following wheat, clover following potato, &c. But, above
all, agriculturists learned that in the long-run there is nothing so
cheap as manure, i.e. the return to the soil by animals of the elements
which these animals took out of it.
On the right hand of the illustration (page 495) is shown the simplest
mode of enriching the soil, namely, by spreading the manure on the
surface of the earth, and then digging it in. Any mode of thus enriching
the earth is a proof of civilisation. No savage ever dreamed of such a
thing, and I doubt whether barbarians recognised the principle at any
time.
Nowadays we have recognised the necessity of returning to the soil in
one form the elements which we have taken from it in another. As usual
in such arts of civilisation, the Chinese have long preceded us. They
waste nothing, carrying, perhaps, its principles to an extent which
scarcely suits our European ideas.
They even utilise the little clippings of hair, to which every Chinaman
is almost daily subject, if he wishes to keep up his self-respect in
public. The barbers carefully preserve these clippings, and sell them to
gardeners. They are too precious to be used in general agriculture, but
the flower artist, when he plants the seed, puts in the same hole a
little pinch of human hair, knowing it to be a strong stimulant to
growth.
* * * * *
WITHOUT multiplying examples of artificial manuring, most of which are
too familiar to need description, we will proceed to the methods by
which Nature has for countless centuries achieved the same work that Man
has lately learned to undertake.
Nature abhors waste, and in the long-run will prove it, however wasteful
may be the ways of her servants. Take, for example, the case of an
ordinary tree, such as an elm, an oak, or a birch. In the autumn the
leaves fall. In the next summer scarcely a dead leaf can be found. They
have been decomposed by rain, dews, and gases, and have thus returned to
the earth more than the nutriment which they took out of it.
Here man is apt to interfere. Knowing the invaluable productive powers
of decayed leaves, he removes them as they fall, and stores them in
heaps so as to form the costly, but almost indispensable, “leaf mould.”
In so doing, however, he deprives the trees of their natural nutriment,
and by degrees they dwindle and die.
Nature, in this case, shows her superiority over Art.
Then we have the remarkable fact that millions of animated beings die
annually, and no vestige of their remains is found. Hyænas and vultures
might account for a few bodies, the remnants of which have been found in
ancient caverns. But there is no hyæna which could crush the leg bones
of an adult elephant; and yet I suppose that neither in Africa nor Asia
has any one discovered the body of an elephant or rhinoceros that had
died a natural death.
In the first place, there is the curious point, which I have already
mentioned, and which is shared by nearly every race of human savages,
that when an animal feels that it has received its death-stroke, it
accepts the conditions, withdraws itself from those who yet have life in
them, and yields up its life as calmly as if it were but sleeping.
But what becomes of the body? As to such enormous beings as elephants,
the various species of rhinoceros, and whales, which are as large as
several elephants, rhinoceros, and hippopotamus put together, I cannot
say from practical knowledge.
Still, as size is only comparative, the rule that holds good with a
small animal may hold equally good with a large one. It is my lot to
walk very often upon the banks of the Thames. It is a charming walk at
high water, but at low water there is too much odoriferous mud, and
there are too many dead dogs and cats to make it an agreeable resort,
except for enthusiastic entomologists, who seem to swarm in this
neighbourhood.
Scarcely has such a carcass been stranded than it is beset by
Burying-beetles of various kinds. Hundreds upon hundreds can be shaken
out of the corpse of a dog or cat, and, before the next tide has come
up, there is scarcely any flesh left on the bones, it having been dug
into the earth by the Burying-beetles.
* * * * *
THEN there is that wonderful family of Scarabæus-beetles, which do us
invaluable service as scavengers and agriculturists. They follow the
path of the caravans, and effectively cleanse the course which has been
traversed. Even man is obliged to utilise as fuel the droppings of the
horses, cows, and camels; but the Scarabæus goes further, collecting all
that man does not need, and burying it in the earth.
The instinct of the female Scarabæus urges it to gather together the
rejecta, to form them into balls, placing an egg in the middle of each
ball, and to bury them in the ground. Thus a double object is attained,
the offensive substances being removed from the surface of the ground,
where they do harm, and being transferred below the surface, where they
do good.
Even the curious instinct of the dog, which leads it to bury bones, &c.,
which it cannot consume, and which it often forgets, if well fed, leaves
them to be consumed by the all-absorbing earth.
[Illustration: SCARABÆUS-BEETLES.]
[Illustration: MEN MANURING GROUND.]
It is evident that, in the end, the earth _must_ receive back again that
which has been taken from it. If, for example, we follow the present
most wasteful plan of drainage, and fling into rivers everything which
ought to be utilised on land, it only gets into the sea in the end, and
in the course of years is decomposed, and returns to the earth in the
form of gases. Meanwhile, however, we have robbed the locality, deprived
it of the nourishment which it required, and forced ourselves to supply
it elsewhere at a costly rate.
So runs the cycle of creation. Sooner or later, Nature will have her
way, and the more we help her, the better it will be for us.
* * * * *
OF course I do not mean to condemn Drainage, which is an absolute
necessity in agriculture, and a matter of life and death in households.
But, when rightly conducted, it only signifies that water is removed
from a spot which is overstocked with moisture to one where it is
needed. Wet clay lands, for example, which were unproductive in point of
crops, and injurious in point of human health, have been converted by
judicious drainage into fertile and healthy grounds.
This, as it will be seen, is a very different business from removing
from the soil the elements which rightly belong to it, and which sooner
or later, in some form or another, it will claim and recapture.
Still, it is evident that in the progress of civilisation there must be
accumulations of all kinds of refuse, which savages utterly disregard.
Then we come to the question of the Drain combined with the Sewer, and
are enabled to see how the hand of man, if properly directed, only
follows the course of Nature.
[Illustration: TUNNEL OF MOLE.]
[Illustration: SEWER.]
So we undermine our towns with a complex system of drains which are
understood by only a very few people. For example, just as a tree is
only half visible, the roots being about equivalent to the branches,
London is only half visible, the subterranean architecture being little,
if at all, inferior to that of the surface.
Here, again, we are met by Nature. Very few of us can appreciate the
extensive subterranean works which underlie us, even where the hand of
man has never been placed. Putting aside a multitude of tiny creatures,
there are, in our own country, the earth-worms which pierce the ground
in all directions, at the same time draining and manuring it. They
penetrate it with their little burrows, thus admitting the air, which
the earth needs as much as we do, and allowing moisture to take its
right place. Then there are the moles, that are perpetually travelling
after the earth-worms, and making drainage galleries of wonderful
extent. Then there are the numerous other burrowers, such as rabbits,
mice, and rats, which are common everywhere, besides the less plentiful
foxes, badgers, and various burrowing birds, all of which assist more or
less in the drainage of the earth.
Even bees and wasps of different kinds assist in this work, the hardest
soil yielding to their small, though powerful, jaws and feet, and so
being made, if only temporarily, able to carry off the superabundant
moisture.
* * * * *
[Illustration: TAIL OF LOBSTER.]
[Illustration: FLEXIBLE WATER MAIN.]
One of the most ingenious modes of Drainage was that which was invented
by Watts, and was avowedly based on Nature. He had engaged himself to
carry a drain tube through, or rather over, an extremely irregular bed
of a river, where the pipes must accommodate themselves to existing
conditions. The modern system of pipes not having been brought into
existence, Watts had to adapt himself to circumstances, and did so by
making his pipe on the model of a Lobster’s tail, as shown in the
illustration.
We have already seen how the same object has been utilised in warfare as
a pattern for armour, but it does seem rather strange that it should be
employed in the tranquil arts of peace.
* * * * *
ANOTHER method of removing superfluous water is by the TURBINE PUMP, by
which the water, instead of being cast up in successive jets, was flung
out in a continuous torrent. Some of my readers may remember the
sensation which was created at the first Exhibition of 1852 by the then
extraordinary powers of the Turbine Pump.
Yet this is, after all, nothing but an imperfect copy of the now
celebrated being to which human beings have been supposed to owe their
origin, namely, the Ascidian, popularly known by the name of the
Sea-squirt, and with very good reasons.
As a rule, it keeps up a rotation of tentacles, such as is shown in the
illustration, acting exactly on the principle of the Turbine Pump, and
drawing in and discharging water with a power that is perfectly
astonishing in so small a being. Beside this, it has the power of
flinging out at once the whole of its watery contents, and any one who
has incautiously handled a mass of Ascidians, and been drenched by them,
can answer with more truth than satisfaction as to the water-absorbing
power of the Turbine.
[Illustration: ASCIDIAN.]
[Illustration: TURBINE PUMP.]
Then the Ascidian can do what the Turbine cannot do. In the Turbine the
water which is taken in must necessarily be ejected in equal
proportions. With the Ascidian the same thing takes place, but with the
additional power of ejecting all the contained water, and then beginning
afresh.
There is now no doubt that the Circular or the Turbine Pump is the most
powerful in such cases as emptying mines of the water which, in spite of
all precautions, will make its way in, and destroy the labours of the
miners. But I merely wish to carry out the object of this work by
remarking that the invaluable Turbine Pump is only a very inferior copy
of a natural pump, which existed, as far as we know, centuries before
Man could find his place upon this earth.
THE SPIRAL.
In an early portion of this work the Spiral or Screw was touched upon,
mostly in connection with the propulsion of vessels. We will now extend
it a little further, and see how it is modified so as to perform other
offices than those which have been described.
Allusion has already been made to the Spiral or Wedge principle, but
some of the illustrations were accidentally omitted. I therefore
introduce them here, this being a chapter of miscellanea.
The Windmill has previously been described, as has also the ship’s
Screw, another form of which is here given.
[Illustration: BIRDS’ WINGS AND TAILS.]
[Illustration: SMOKE-JACK. SHIP’S SCREW. WINDMILL. KITE.]
In the centre is shown the mechanism popularly known as the Smoke-jack,
though it really works by means of hot air, and only becomes gradually
choked by the soot which the smoke by degrees deposits upon it. It is,
in fact, nothing but a windmill working horizontally instead of
vertically, the vanes being moved by the rapidly ascending heated air.
So powerful is the spiral pressure of this air, that in my old college
days at least a dozen rows of heavily laden spits were perpetually
turned by a single Smoke-jack. It is many years since I visited my old
college, and I cannot say whether the Smoke-jack still exists, but, as
it did its work well so long ago, I presume that it does so now.
Then there is the well-known spiral ventilator set in the windows of
workshops. Perhaps its revolution may not assist the air-current, but it
does, at all events, show how much exhausted air has to be expelled from
the room, and consequently how much fresh air needs to be brought into
it.
* * * * *
PERHAPS the reader may be surprised to see that the Wings and Tail of a
bird and a boy’s Kite are placed among the examples of the Spiral
principle. Yet such is the fact. If the reader will move up and down the
wings of any bird which will not bite him, he will find that there is in
them a peculiar screwing motion, difficult of description, but very
observable.
It is mostly for want of this movement that all our attempts at fitting
wings to human beings have been such utter failures. We can make the
wings work up and down well enough, but we cannot as yet impart to them
the all-important spiral movement.
* * * * *
THAT very well-known toy, the Kite, is another example of the same
principle which drives the screw steamer. Its “tail,” which need be
nothing but a piece of string with a proportionate weight at the end,
keeps the Kite in a slanting position, providing that the “belly-band”
be properly arranged. The consequence is that the pressure of the wind
acts on it as on a wedge, and so drives it upwards until the combined
weight of itself and the string counterbalance the upward pressure.
Indeed, the only object of the string is to keep the Kite at a proper
inclination; and, if that object could be attained by the force of
gravity alone, the Kite would ascend to a height nearly double that to
which it can at present attain.
CENTRIFUGAL FORCE.
Closely connected with the spiral principle is Centrifugal Force, that
marvellous power which gives to our whole solar system its ceaseless
movements, and may extend, as far as we know, to other and vaster
systems yet unknown.
Tie a ball to a string, and swing it round, and it will be an exact,
though rough, representation of the double power by which the movements
of the heavenly bodies are governed, our earth being included among
them.
The string represents the force of attraction, which binds all our
planets to the sun, and their satellites to the planets, while the force
that is employed in swinging the ball represents the mysterious power
that issues from the sun, and gives motion to the planets. The metaphor
is a very homely one, but it is nevertheless correct.
* * * * *
IN the accompanying illustration are several examples of Centrifugal
Force as found both in Nature and Art. On the left hand we have diagrams
of some of the heavenly bodies, showing the revolution of their
offspring, so to call them, while on the right are seen examples of
Centrifugal Force as applied to human use. For convenience’ sake, the
illustrations have been separated into two portions.
[Illustration: CENTRIFUGAL FORCE OF HEAVENLY BODIES.]
[Illustration: CENTRIFUGAL FORCE OF “GOVERNORS” OF ENGINE. SLING.
AMENTUM AND MOP.]
In the first of these illustrations we have the “Governor” of the
steam-engine, that wonderfully ingenious and simple piece of mechanism
which controls the force of the steam, and, without the superintendence
of man, acts almost as a living being might.
It is composed of two heavy metal balls, hinged, as shown in the
illustration, to a movable collar which slides up and down the central
rod. When the engine is at work the Governor revolves, and the harder it
works, the more rapid is the revolution. Consequently, as it revolves,
the balls diverge and draw the sliding collar up the rod.
Here lies the whole beauty of the invention. The sliding collar is
connected with the safety-valve. Thus, if the engine should be working
beyond its proper powers, the Governor draws up the collar, and releases
sufficient steam to take the undue pressure off the boiler. Thus the
engine may be left, so to speak, to manage itself.
* * * * *
NEXT are shown two examples of Centrifugal Force as applied in ancient
warfare, namely, the Sling, which is now retained merely as a boy’s toy,
and the Amentum, which was practically a sling attached to a spear. Both
weapons have been superseded by the modern firearms, but the Sling is
really a more formidable offensive weapon, in skilful hands, than is
generally suspected.
A good slinger is as sure of his aim as a good rifleman, and can send
his missile to a wonderful distance. Were I to be armed with the best
pistol hitherto invented, I should be sorry to fight an accomplished
slinger, unless under cover.
The really tremendous power of the Sling is obtained by Centrifugal
Force, the weapon, with its missile, being whirled in the air, and then
one string being loosed with a peculiar knack something like the “loose”
of a good archer. In consequence, the centrifugal force is converted
into direct force, and the missile flies directly forwards.
The Amentum is simply a cord tied to a javelin, so that the thrower has
the advantage of a lever, which, after all, is only the conversion of
centrifugal force.
The very familiar Mop, flinging off its moisture to a considerable
distance, needs no description; but I have introduced it to show the
action of centrifugal force in small as well as in great things.
* * * * *
THE next illustration shows how this very same power acts upon the
greatest as well as the least of objects, and enables them to maintain
positions which otherwise they must of necessity fail to do. Take, for
example, our own Earth, and its peculiar position of being tilted on one
side, so as to give us the alternative seasons as it flies on its annual
course.
This is simply due to its own rapid revolution, which, on the same
principle that keeps the arrow and the rifle-ball straight on their
course, prevents it from altering its position.
The very same principle acts on the boys’ Tops, and is shown in a really
remarkable manner by the professional Japanese top-spinners, who will
place several tops upon each other, as shown in the illustration, and
make them sway backwards and forwards in the most extraordinary manner,
sometimes being all upright, and sometimes leaning almost at right
angles to each other.
A favourite mode of illustrating this power of Centrifugal Force is by
the Gyroscope, a figure of which is given on the right hand of the
illustration. The interior wheel is made to revolve rapidly, and the
effect of the revolution is to enable the instrument to maintain a
horizontal position, even when suspended on one side, as shown in the
engraving.
[Illustration: REVOLUTION OF EARTH.]
[Illustration: JAPANESE TOPS.]
[Illustration: GYROSCOPE.]
The power of this revolution is quite wonderful, even in a small
Gyroscope which can be purchased for a few shillings. It almost seems to
be alive, and to insist on retaining its position, in spite of all
efforts to the contrary.
This principle is used in the swinging cabin of the Bessemer ship, and
is also employed by quoit-players in keeping their missile steady as it
flies towards the mark. Even the now fashionable Bicycle is managed on
the same principle.
As is well known to all bicycle riders, it is comparatively easy to
maintain the balance when the pace is rapid and the wheels revolving
quickly. The difficulty is, to do so when the pace is slow, and the
rider is deprived of the centrifugal force which keeps him on his
balance almost in spite of himself. It is just the same with a child’s
hoop, which runs straight and upright when it is driven rapidly, or
when, for example, it runs downhill. But, as soon as the centrifugal
force is expended, it begins to waver, loses its direction, and soon
falls to the ground.
USEFUL ARTS.
CHAPTER XVII.
OSCILLATION.--UNITED STRENGTH.--THE DOME.
Connection of Oscillation with Centrifugal Force.--Equality of Time
in Oscillation.--The Spider.--The Stone and String.--Pendulum of
the Clock, and its Effect on the Machinery.--Acceleration and
Retardation.--Compensating Pendulums.--The Metronome, and its Use
in Music.--A simple Metronome.--Value of the Instrument in
War.--The Escapement, and its Connection with the Pendulum.--Mode
of Action.--Larva of Burying-beetle.--Earthworms and
Serpents.--Union is Strength.--The Hippopotamus Rope and its
Structure.--The Spider-web.--Distinction between the
Threads.--Principle of the Dome.--The Arch, and its Connection with
the Dome.--Esquimaux Huts.--Receiver of the Air-pump, and its Power
of Resistance.--The Human Skull and the Egg.--Accidental
Resemblance.--The Salad-dressing Bottle.--The Medusa, Strobila, and
Hydra.
A portion of our last chapter dealt of Centrifugal Force. We will now
proceed to another well-known power, which seems to be a variation, or
perhaps a division, of the same power. I mean the principle of
OSCILLATION, which has done so much for the present state of the world.
I mention the connection of the two principles because it is evident
that, if Oscillation were continued in one direction, it would be
converted into centrifugal force. In fact, it can only be considered as
centrifugal force interrupted.
The chief point in this subject is the equal time occupied by the
oscillating body, no matter what may be the “arc” distance through which
it sways, provided that the length of the line remains the same. The
discovery of this principle by Galileo in a church at Florence is too
well known to need repetition.
This principle may be observed by any one, and at almost any time. The
Spider at the end of its line illustrates it, and so does a stone tied
to a string, both of which objects are shown in the illustration.
* * * * *
IN various departments of Art, Oscillation is absolutely invaluable. We
will take, for instance, the best known of these examples, namely, the
Pendulum, by which the movements of clocks are regulated. Without some
mode of regulation, the works would run down rapidly, and the clock
rendered incapable of measuring time. But, in the Pendulum, we possess a
means of making a clock go at any desirable rate, and be faster and
slower at pleasure; a long Pendulum working slowly, and a short one
rapidly.
[Illustration: SPIDER.]
[Illustration: OSCILLATING WEIGHT.]
[Illustration: METRONOME.]
[Illustration: PENDULUM.]
How the Pendulum affects the working of a clock may be seen by reference
to the right-hand figure of the illustration. The movements of the clock
are connected with the Pendulum by means of an ingenious piece of
mechanism called an “escapement,” because it only allows the wheel shown
in the illustration to move one cog at each swing of the Pendulum.
Now, as in the latitude of London a pendulum which is a trifle more than
thirty-nine inches in length swings once in a second, it is evident
that, by lengthening or shortening the Pendulum, we have the rate of the
clock entirely under command.
For example, if a Pendulum be required to swing once in two seconds, it
must be four times as long as that which swings once in one second,
while to swing once in three seconds it must be nine times as long, the
length being measured by the square of the time of vibration.
We are thus able to “regulate” clocks by lengthening the Pendulum if
they be too fast, and shortening them if they be too slow. The reader
will probably have remarked that the conditions of the atmosphere--such
as heat, cold, moisture, or dryness--must have an effect on the length
of the Pendulum, and thus alter the rating of the clock. So they do, and
in consequence the Compensating Pendulums have been invented, some of
them being made of metallic rods of different powers of expansion,
mostly brass and steel, while others carry a quantity of mercury in a
glass tube near the bottom of the Pendulum.
* * * * *
ANOTHER familiar example of the Pendulum is the Metronome, which is
simply a Pendulum with a weight at the top as well as counterpoise below
the bottom, the weight moving up or down so as to decrease or hasten the
pace. Generally a bell is added to it, which is struck at the beginning
of each bar.
The exactness of its beats is perfect, as is known to all musicians, and
is calculated to take the conceit out of players who are apt to
disregard their time. I knew one lady, a really good pianiste, before
whom I placed my Metronome. Before she had played many bars she broke
down, exclaiming that the horrid bell always said “ting” in the wrong
place. However, she soon acknowledged the value of the instrument, and
was glad to use it.
A very good Metronome may be made by fastening a bullet to the end of a
piece of tape, and swinging it backwards and forwards, regulating the
tape according to the time required. Such a Metronome is very portable,
and extremely useful where the conveyance of the clockwork instrument
would be troublesome. Moreover, its beats can be seen by a great number
of persons. I have often used it myself.
Such a Metronome is used in the army, in order to regulate the pace of
the soldier’s step, it being of the last importance that the pace should
always be the same. Otherwise it would be impossible to calculate the
time which ought to be consumed in marching a certain distance, and the
military calculations on which depends the success or failure of a
campaign would be wholly upset, half an hour too soon or too late
meaning failure.
THE ESCAPEMENT.
As we are on the subject of the pendulum and Escapement, we will say a
few words about the latter piece of mechanism. It is here given on a
larger scale than in the previous illustration, so that its action may
be more easily understood. Whether in watch or clock, the Escapement is
exactly the same in principle.
[Illustration: LARVA OF BURYING-BEETLE.]
[Illustration: ESCAPEMENT OF WATCH.]
First there is the escapement wheel, the circumference of which is
furnished with a number of very deep cogs, varying as to the work which
they have to do. Then there comes the escapement itself, which swings on
its pivot, and is regulated in its oscillations by the pendulum. As it
swings backwards and forwards, it is evident that only one tooth of the
wheel can “escape,” and only that in one direction.
We can reverse a steam-engine, but the man has yet to be found who can
reverse a clock, _i.e._ enable it to continue going in the opposite
direction. The only mode would be to enable one set of cogs to flatten
themselves, so as to pass the escapement, and a second set to start up
in exactly the opposite direction. Or perhaps there might be two
parallel escapement wheels, capable of being connected or disconnected
with the clock at pleasure. As, however, a reverse movement is quite
needless, no such invention seems to have been made.
* * * * *
ON the left hand is seen an example of the same principle as shown in
Nature. It represents a larva or grub of the Burying-beetle. It has no
legs available for locomotion, and yet it can get along with tolerable
speed.
Many years ago, when living in Wiltshire, I was much struck with this
fact. There had been an epidemic among sheep, which killed them off so
fast that the farmers would at last not even bury them, but took off the
skins, and left the bodies to moulder as they best might.
It was very unpleasant for the farmers, but just the contrary for the
Burying-beetles, which simply swarmed in the deserted carcasses. If one
of them were tapped with a stick, hundreds of these larvæ came scuttling
out, displaying an activity which was really remarkable in creatures
practically legless.
In reality this movement is achieved by an apparatus very similar in its
action to that of the escapement. The rings, or “segments,” of which the
body is composed, are furnished with rows of sharp points, arranged very
like the cogs of the escapement wheel. By alternately elongating and
contracting the body, these points catch against surrounding substances,
and force the creature onwards, only allowing of movement in one
direction.
Perhaps the reader will remember that in an earlier part of this work it
has been mentioned that the various worms propel themselves by the same
means. So do the Serpents, the edges of the scales serving the same
purpose as the hairs of the worms and the hooks of the grub.
UNION IS STRENGTH.
ON the left hand of the accompanying illustration we have an example of
the wonderful power obtained by uniting together a number of
comparatively weak objects. It represents a portion of the rope attached
to the harpoon with which the natives of some parts of Africa attack and
kill the hippopotamus.
Considering that a full-grown hippopotamus weighs several tons, and, in
spite of its enormous size, is as active as a tiger, we can infer the
strength of the rope which must be needed to hold such an animal when
excited with rage and pain.
A few years ago the female hippopotamus at the Zoological Gardens, when
deprived of her cub, actually tried to leap over the lofty iron barrier,
and so far succeeded as to throw her weight on the uppermost bar.
Fortunately it was made of well-wrought iron, and was only bent by her
weight. Had it been made of cast-iron, like most railings, she would
have snapped it like glass.
Now, the fibres of which the rope is composed are individually feeble,
but, when they lend their strength to each other, their strength is
amazing. It is well shown by a lasso in my possession, made of the
fibres of the aloe-leaf. It is scarcely as thick as a man’s little
finger, and yet it is strong enough to resist the efforts of the most
powerful wild bull. I have some of the separate fibres, and it is
interesting to notice how fibres so slight when separate should be so
strong when united. Part of the rope has been unlaid, so as to show the
manner in which it has been put together.
[Illustration: HIPPOPOTAMUS ROPE.]
[Illustration: SPINNERET OF SPIDER.]
Towards the harpoon itself, a number of small cords laid loosely side by
side are used, so as to prevent the hippopotamus from severing the rope
with his chisel-like teeth, which he would assuredly do if it were
single. The multitudinous cords become entangled among the teeth, and
baffle his efforts; but still their unity is their strength; and, though
the animal may sever one or two of them, the others retain their hold
until he dies under a shower of spears.
* * * * *
ON the right-hand side of the illustration is the Spinneret of the
ordinary garden Spider, showing the many orifices from which the silken
threads emerge. It is a remarkable point, and one which, I believe, is
seldom noticed, that the Spider can at pleasure combine all these fibres
into a single cord, or issue and keep them separate, just as is the case
with the hippopotamus rope.
The latter operation may be seen whenever a large fly gets into the web.
The Spider darts at it, bites it, and then, ejecting a loose mass of
fibres, rolls it up in a moment, as in a shroud, carries it off and
hangs it in a convenient place, and mends the broken meshes of the web.
But both kinds of the cords of the net are made differently from the
winding-up fibres, the former being fixed together, and the latter kept
separate.
PRINCIPLE OF THE DOME.
We are all familiar with Domes, especially when the Dome of St. Paul’s
is the most conspicuous object in our metropolis. Few persons, however,
except professional architects and builders, seem to ask themselves the
principle on which the Dome is constructed.
The strength of the arch is well known, and the Dome is practically a
number of arches, affording material support to each other, and so
enormously increasing the strength of the edifice.
A good idea of the Dome principle may be formed by taking two croquet
hoops, placing them at right angles to each other, tying them together
at the intersection, and pushing the ends in the ground. Even by this
very simple arrangement considerable strength can be obtained; but, if
the hoops be sufficiently multiplied to form a close Dome, it will be
evident that the strength will be correspondingly increased.
So strong, indeed, is the Dome, that it could be made without mortar or
cement, although, of course, its strength is increased by their use. A
very good example of a Dome thus constructed is found in the “igloo,” or
snow-hut of the Esquimaux, which has already been described.
As to the example which I have selected, it would have been easy enough
to have chosen one of the great Domes of the world, such as St. Peter’s
at Rome, St. Maria del Fiore at Florence, St. Paul’s of London, or St.
Geneviève or the Invalides of Paris.
I have, however, selected the present example on account of the thinness
of its walls, the fragility of its material, and the enormous pressure
which it has to undergo. This is the “Receiver” of the Air-pump. It is
made of glass not thicker than an ordinary tumbler, and yet, even when
exhausted of air, it will resist the pressure of the atmosphere for
days together.
When it is remembered that the Receiver is deprived of its internal air,
and therefore has to resist a pressure equal to fifteen pounds on every
square inch of its surface, it may be imagined how strong the Dome is.
Were the top or either side to be flat, it would be crushed as soon as a
vacuum was formed sufficient to deprive it of the support of the air
within.
* * * * *
A GLANCE at the illustration will show how the Receiver is modelled on
the same plan as the Human Skull, the outlines being curiously similar.
It is this formation which imparts such strength to so thin a set of
bones as those which compose the human skull as enables them to protect
a sensitive organ like the brain, on which both reason and life itself
depend.
[Illustration: HUMAN SKULL.]
[Illustration: RECEIVER OF AIR-PUMP.]
Eggs also form good examples of the wonderful strength obtained by this
principle, their thin shells protecting the yolk and the white, as well
as the chick through its progress to maturity.
* * * * *
THE last subject in this chapter is a curious example of an evidently
accidental resemblance in form.
The figure on the right of the accompanying illustration will at once be
recognised as one of those Salad-dressing Bottles which try to conceal
by their shape the small volume of their contents.
That on the left represents one of the many forms through which the
Medusa passes before it attains its perfect form. It was long thought
to be a separate creature, and was known under the scientific name of
Strobila. Modern researches have, however, made the discovery that it is
one of the transitional stages between the creature known as the
Trumpet-hydra (_Hydra tuba_) and the Medusa, popularly known as
Jelly-fish.
The former almost exactly resembles the Hydra of our fresh waters. It is
a tiny transparent gelatinous bag--so transparent as to be scarcely
perceptible, and with some thirty or forty long and delicate tentacles
hanging from its open end. These tentacles are used in catching the
minute creatures on which it feeds. It is fixed, and, to use Mr. Rymer
Jones’s simile, looks like a beautiful silk-like pencil waving amidst
the water. Its length is not quite half an inch.
[Illustration: TRUMPET-HYDRA.]
[Illustration: SALAD-DRESSING BOTTLE.]
That it should be identical with the remarkable form shown in the
illustration seems impossible, but such is the case. Its body becomes
contracted as if tied with strings, and every segment thus formed
develops a set of tentacles, breaks away, and swims off in the form of a
Medusa. The upper segment is exhibited as undergoing this process.
The figure is magnified so as to show the structure better, its right
length being about one-third of an inch. A full and graphic history of
this creature and its manifold changes may be found in Mr. Rymer Jones’s
“Aquarian Naturalist.”
It is not likely that the inventor of the Salad-dressing Bottle ever saw
a Hydra, but the resemblance is strangely exact.
ACOUSTICS.
CHAPTER I.
PERCUSSION.--THE STRING AND REED.--THE
TRUMPET.--EAR-TRUMPET.--STETHOSCOPE.
The Science of Sound.--Rhythmical Vibrations.--The Drum.--Primitive
Drums.--The Solid and Hollow Log.--The Bass Drum and
Kettle-drum.--African Drums.--Gnostic Gems and the Ashanti
Drum.--Tympanum, or Drum of the Human Ear, and its Mechanism.--An
artificial Tympanum.--The String.--The Bow and the Harp.--The
Harpsichord and the Zither.--The Bow and the Violin.--The
Cricket.--The Vibrator, or Reed.--The Jew’s Harp and
Harmonium.--The Cicada and its Song.--Harmonics upon Strings.--The
Æolian Harp.--Harmonics upon the Trumpet.--The Trombone.--Trachea
of the Swan.--The Ear-trumpet.--The Sea-shell.--The
Stethoscope.--Savage Food.--The Aye-aye.--The Siren and its
Uses.--Echo and Whispering Gallery.
In a work of this nature it would be absolutely impossible, not to say
out of place, to give an account of so elaborate a subject as Acoustics,
_i.e._ the science of Sound. Suffice it to say, that all sounds are
produced by the vibration of air, and that the fewer vibrations, the
lower is the sound, and _vice versâ_.
When such vibrations are produced regularly, they form Musical sounds,
but, if irregularly, the sounds can be only distinguished under the term
of Noise. The earliest germ of music lies in certain savage races, who,
as long as they can maintain a rhythmical beat on any resonant
substance, do not particularly care what it is. A hollow tree is a
splendid instrument in their opinion, but, if this cannot be had, a dry
log of wood will answer the same purpose.
Some tribes, more ingenious than others, cut a deep groove upon the
upper surface of a log, hollow it through this groove, and then hammer
away at it to their hearts’ content. The next move was to cut off a
section of the trunk of a tree, hollow it, set it on end, and then beat
it on the sides.
Lastly, some one hit upon the idea that if the open upper part of the
hollowed log were covered with a tightly stretched membrane, and that if
the membrane, instead of the log, were beaten, the resonance would be
increased. In consequence, the real Drum was invented, and seems to have
existed from time immemorial in parts of the world so distant that they
could not have had any communication with each other.
Take, for example, the well-known “Bass Drum” of our bands, which is
shown on the right hand of the figure. We make it a very ornamental
article, with frame of metal, and heraldic decorations of all kinds.
[Illustration:
BONES AND DRUM OF EAR.
_a_ TUBE OF EAR.
_b_ DRUM.
_c_ HAMMER.
_d_ ANVIL.
_e_ STIRRUP.]
[Illustration: DRUMS.]
Lying against it is one of a pair of Kettle-drums, such as are always
seen in mounted bands. They look very easy to play, but, if the reader
will try a pair, he will soon find his mistake.
But there are savage tribes of Western Africa who make Drums of such
wonderful power that their sullen roar is heard for miles around, as
their slow, triple beat summons the tribe to arms like the fiery cross
of the Highland clans. As to shape, lightness, and beauty, our Drums are
infinitely superior to theirs, but, so far as I can gather from personal
and written narratives of African travellers, none of our Drums surpass
theirs in richness, depth of tone, and power of carrying sound.
Sometimes these Drums, instead of being mere cylinders, are carved into
the most strange and fantastical patterns. I possess one of these
curious Drums, brought from Ashanti, and carved out of a solid piece of
wood.
The strange point in it is, that it represents a double head carrying,
after all negro fashions, a sort of vessel upon it. One part of the head
represents a human head (not that of a negro), while the other merges
gradually into an eagle’s head and beak. It is, in fact, a Gnostic gem,
and would pass muster as such if it had been engraved on chalcedony,
cornelian, or other semi-precious stones which are employed in the
seal-engraver’s art.
Upon this composite head is placed the Drum itself, which is also cut
out of the solid block, and which, after the fashion of West African
Drums, has a hole on one side.
This remarkable instrument was given to me by an old merchant captain,
who brought it himself from West Africa, and who, when I made his
acquaintance, had actually painted it all kinds of colours, planted it
in his garden, and was using the Drum as a flower-pot. Of course, as
soon as it came into my possession, I put it in “pickle,”--i.e. a strong
solution of alkali,--brushed off the paint, and placed it in my museum,
where it is now.
* * * * *
ON the left hand of the illustration on page 514 is given a sort of map
or chart of the human Ear, with its internal Drum, or Tympanum, as it is
scientifically termed.
It is by the vibration of this Drum that hearing is made possible, the
vibrations of the air being transmitted to the Drum by means of a
beautiful bony apparatus, termed the Hammer, Anvil and Stirrup.
Sometimes the action of the Drum is partially checked, and then the
sufferer is said to be “hard of hearing.” Sometimes it is broken, or its
action totally clogged, and then he is said to be “stone deaf.” There
have been cases where an artificial tympanum has been inserted, and
answered its purpose fairly well.
THE STRING AND REED.
It has previously been mentioned that all sounds are owing to vibrations
of the air. But there are many ways of producing these vibrations, and
each mode gives a different quality of tone. We have already seen, by
means of the drum, how sound is produced by percussion. We shall now see
how sounds can be produced by the vibrations of a String.
If the string of a bow be pulled and smartly loosed, the result is a
distinctly musical sound, higher or lower according to the length and
tension of the string. Perhaps some of my readers may recall the passage
in Homer’s “Odyssey,” where Ulysses strings the fatal bow:--
“Heedless he heard them; but disdained reply,
The bow perusing with exactest eye.
Then, as some heavenly minstrel, taught to sing
High notes responsive to the trembling string,
To some new strain when he adapts the lyre,
Or the dumb lute refits with vocal wire,
Relaxes, strains, and draws them to and fro;
So the great master drew the mighty bow,
And drew with ease. One hand aloft displayed
The bending horns, and one the string essayed.
From his essaying hand the string let fly,
Twanged short and sharp, like the shrill swallow’s cry.”
The Harp is, in fact, nothing but a magnified bow, with a number of
strings of graduated length and tension. Some very beautiful experiments
have been made on this subject by the Rev. Sir F. A. G. Ouseley,
Professor of Music at Oxford, who stretched a string of sixty-four feet
in length, and found that although, when vibrating, it must produce a
note, there was no human ear that could distinguish it. Yet, if combined
with other musical instruments, it would probably do its work well. The
theory of the vibrations will be briefly described on another page.
These vibrations may be produced in various manners. The string may be
pulled with the fingers, as in the harp, the guitar, the zither, or even
the violin, &c., in pizzicato passages.
The old harpsichord, now an instrument vanished into the shadows of the
past, pulled the strings with little strips of quill, acting like the
thumb-ring of the zither-player. The “plectrum” of the ancients acted in
the same manner, and the Japanese have at the present day a sort of
guitar played with a plectrum. I have heard it, but cannot particularly
admire the effect, the notes appearing to be without feeling, and as if
they were played on a barrel-organ.
Sometimes, as in our modern pianos, the strings are struck by hammers
instead of being pulled by fingers, plectrum, or goose-quill.
The most ingenious mode of causing musical vibration is the Bow, which
is too familiar to need a detailed description. Suffice it to say that
it really is a modified bow, the place of the string being supplied by a
flat band of horsehair, which is drawn over the string, and so causes it
to vibrate. In order to enable the bow to grip the string, it is rubbed
with resin almost as often as a billiard-player chalks his cue.
Some skill is required even in producing a sound by the bow. It looks as
if any one could do it, but a novice, if he extorts any sound at all,
never rises above a squeak. When I took my first violin lessons, nearly
thirty years ago, I was so horrified at the discordant sounds elicited
from the instrument, that I retired to the topmost garret of the house
in order not to hurt any one’s feelings except my own.
[Illustration: CRICKET.]
[Illustration: CICADA.]
[Illustration: VIOLIN.]
[Illustration: JEW’S HARP.]
* * * * *
ON the left hand of the illustration is seen a well-known example of the
imitation of Nature by Art. This is the common Cricket, whose loud
shrill call is more familiar than agreeable.
Some years ago, while engaged on my “Insects at Home,” I gave much time
to the examination of the structures by which such a sound can be
produced. On the under side of the wing-covers, or “elytra,” as they are
scientifically termed, are notched ridges, which, when examined with a
moderate power of the microscope, have something of this appearance
~~~~~~~. The friction of these notches produces the musical sound,
which, as the reader will see, is exactly analogous to the friction of
the bow upon the string.
* * * * *
NEXT we come to the Vibrator, sometimes called the Reed. It is
introduced into various musical instruments, such, for example, as the
harmonium, the clarionet, the oboe, the bassoon, and various organ
pipes.
The simplest form of the Vibrator is shown in the Jew’s Harp, as it is
popularly called, though it is not a harp, and has nothing to do with
Jews.
[Illustration: VIBRATING STRINGS.]
[Illustration: ÆOLIAN HARP.]
The word is really a mistaken pronunciation of “jaw’s harp,” because the
instrument is held against the teeth, while its tongue is vibrated by
strokes of the finger. These vibrations affect the air within the mouth,
and, by expanding or contracting the mouth, the sound is lowered or
raised according to the laws of Acoustics. Of course, the range of notes
is very small, being limited to those of the common chord, and even they
being attainable only by a practised performer. Very good effects,
however, have been produced by means of a series of Jew’s Harps, set to
different tones by loading the end of the tongue with sealing-wax or
similar substances.
* * * * *
AN apparatus constructed on the same principle is to be found in the
vocal organs of the male Cicada. If one of these insects be examined on
the lower surface, two curious and nearly circular flaps will be seen,
just at the junction of the thorax with the abdomen. It is by the action
of these two little vibrators that the insect is able to produce a sound
so loud, that in calm weather it may be heard at the distance of a mile.
* * * * *
THE accompanying illustration is, in fact, a sort of chart as to the
vibration of sound.
On the right is shown the ÆOLIAN HARP, with its upper lid raised, so as
to show the structure of the strings. These are all tuned to the same
note, the present D being generally accepted as being most free from
false tuning, and less liable for the errors of “temperament.” Several
of the strings are an octave lower than the others, but the tonic is
always the same.
The instrument is placed in a current of air, generally in a window,
with the sash let down upon it, and the air-currents set the strings
vibrating in a most wonderful manner.
There is no need for human fingers to touch them, but they automatically
divide themselves into the component parts of the common chord, and
produce octaves, fifths, and thirds _ad infinitum_.
On the left hand of the same illustration is exhibited a string of the
same length and tension, vibrating in two different ways. The upper
figure shows it divided into three portions, each of which gives the
fifth above the tonic, and all of which, when sounding simultaneously,
give a fulness and richness to the tone which could only be attained
otherwise by three distinct instruments. All players of stringed
instruments know how invaluable are these harmonics, without which many
passages of well-known music could not be played, and which are produced
by “damping,” and not pressing the strings.
So, if the string be lightly touched, or damped at the crossing portion
at either end, the result will be that the string divides itself into
three portions, and all three resound simultaneously.
The lower string is vibrating in thirds, having divided itself into four
portions. If it were damped in the middle, it would divide itself into
two portions, and sound octaves.
The subject is a most interesting one, but our space is nearly
exhausted, and we must pass to another branch of it.
* * * * *
IN all brass instruments furnished with a mouthpiece, and not with a
reed, the notes are obtained by vibrations of the enclosed air, caused
by the movement of the lips. They are all set to some definite tonic,
sometimes C natural, but mostly to a flat tone, such as B flat or E
flat.
Taking the ordinary military trumpet or bugle as an example, we have
(when we have learned how to play it), first, the tonic. By alteration
of the lips we get the octave above the tonic. Then comes the fifth;
then the third, which is, in fact, another octave; and then a few other
notes, the truth of which depends on the ear of the player.
Now, all these notes are obtained by means of the lips, which set the
column of air vibrating, and divide it into harmonics. The apparently
complicated bugle-calls of the army are nearly all formed from four
notes only, _i.e._ (taking C as the tonic) C G C E G.
* * * * *
[Illustration: TRACHEA OF SWAN.]
[Illustration: TROMBONE.]
The Trombone, which is shown on the right hand of the illustration, has
the advantage of being lengthened at will, and thus giving the performer
a fresh tonic, and consequently another series of harmonics. Valved and
keyed instruments have a similar advantage, the one acting by
lengthening, and the other by shortening, the column of air. The former
is infinitely the better plan, as it sets more harmonics vibrating, and
consequently gives a greater richness of tone.
A familiar example of this is to be found in the Ophicleide and
Euphonium. The former is eight feet in total length, and alters its
tonic by eleven keys, which shorten the column of air. The latter is of
the same length, but, by the employment of valves, can be made sixteen
feet in length. Consequently the euphonium has practically killed the
ophicleide, just as the ophicleide killed the serpent. The
cornet-à-pistons, the brass contra-basso, the flugel horn, the tenor
sax-horn, &c., are all constructed on the same principle.
* * * * *
ON the left hand of the illustration is shown the wonderful apparatus by
means of which the Swan produces its far-resounding cry. The windpipe,
or “trachea,” as it is technically named, passes down the neck,
protected by the bones, until it reaches the chest. There it leaves
them, enters the cavity of the chest, and contorts itself in such a
manner as to obtain greater length, just as is the case with the
trombone and valved instruments.
ACOUSTICS AS AIDS TO SURGERY.
We have already seen how the air-vibrations poured in at the small end
of the trumpet can make resonant notes. We have now to see how the
reverse process can be employed, and sounds poured into the larger end
be conveyed to the ear.
[Illustration: EAR-TRUMPET.]
[Illustration: CONCHA OF HUMAN EAR.]
The Ear-trumpet is a familiar example of such an instrument, and, as it
is shown in the illustration, there is no need of further description.
It is rather remarkable, by the way, that the length of tube does not
seem to interfere with the conveyance of sound, as may be seen by the
speaking-tubes which are now so common in private houses, hotels, and
offices.
I know of one church in which there is a special seat for deaf persons.
The reading-desk and pulpit are both fitted with the large ends of
Ear-trumpets. From them pass tubes under the flooring, and so into the
seat, where they can be applied to the ear of the deaf worshippers.
* * * * *
ON the right hand is the “Concha,” as it is called, of the human ear,
which is evidently constructed for the purpose of collecting and
concentrating sounds. Instinctively, if we wish to near any sound more
distinctly, we place the open hand behind the ear, so as to enlarge its
receptive capacity, and send a greater volume of sound into the ear.
The well-known experiment of holding a shell to the ear so as to hear
the murmur of the sea is due to the same cause, the shell collecting,
though in a mixed manner, all the surrounding sounds, and making a
murmur which really resembles the distant wash of the waves upon the
shore.
[Illustration: SAVAGE TAPPING TREE.]
[Illustration: SURGEON USING STETHOSCOPE.]
Then, if we examine the various animals which need acute hearing, either
to seize prey or escape from enemies, we shall find that they have large
and mobile ears, which can be directed so as to catch the expected
sound. The hare, rabbit, and deer are examples of the latter, while the
former are well represented by the domestic cat, whose ears are always
pricked forward when she hears the scratchings of a mouse.
* * * * *
ANOTHER most useful appliance is the STETHOSCOPE, which enables the
skilful surgeon to investigate the interior of the body almost as
clearly as if it were transparent. It is perfectly simple, being nothing
but a trumpet-shaped piece of wood, formed as shown in the illustration.
Sometimes it is hollow, and sometimes solid, but the result is the
same, sound being transmitted through wood in a most remarkable manner.
For example, if one end of the longest scaffolding pole be slightly
scratched with a pin, the sound will be distinctly heard by any one who
places his ear against the other end, though the person who uses the pin
can scarcely hear the sound himself. The surgeon, therefore, places the
broad end of the Stethoscope upon the patient, and the other upon his
ear, taps more or less lightly with his fingers, and by the sounds
transmitted through the Stethoscope ascertains the condition of the
internal organs.
* * * * *
ON the left hand is an illustration of the mode in which the Australian
savage, without the least idea of the theory of Acoustics, utilises the
sound-conducting power of wood. If he wishes to know whether or not a
hollow tree is tenanted by an animal of which he is in pursuit, he
places his ear against the tree, taps it smartly with his tomahawk, and
listens for the movement of the animal inside.
So delicate is this test, that it is employed even when the native is
hunting for the large beetle-grubs on which they feed, and which are
accounted a luxury even by Europeans, when they have once overcome the
prejudice attaching itself to eating, without cookery, fat white grubs
as thick and long as a man’s finger.
The Aye-aye is said to eat in exactly the same manner, tapping with its
long finger the trunks and branches of trees and, if it hears a maggot
inside, gnawing it out.
MEASUREMENT OF SOUND.
Of late years we have had an instrument which enables us to measure the
vibrations of sound as accurately as the barometer measures the weight
of the atmosphere, the thermometer the temperature, and the photometer
the power of light. This is the Siren, which is shown on the right hand
of the accompanying illustration.
To explain this instrument fully would require ten times the space which
we have at command, and necessitate a great number of drawings. I will,
therefore, endeavour to explain its principle in as brief terms as
possible.
The reader will observe that at the lower part of the instrument there
is a disc pierced with a number of holes, and that above these are two
dials. Below the perforated disc, and therefore unseen, is a circular
plate, also pierced with holes. When a pipe is attached to the lower
part of the instrument, and air propelled through it, the disc begins to
revolve, every revolution being recorded by the dials, after the fashion
of the ordinary gas-meter.
[Illustration: GNAT.]
[Illustration: HUMBLE-BEE.]
[Illustration: SIREN.]
As the pressure is increased, the air, passing through the holes,
assumes a rhythmical beat, which soon becomes metamorphosed into musical
notes. It is evident, therefore, that, by means of this instrument, the
number of vibrations which produce a definite tone can be measured with
absolute accuracy by any one who has an ear capable of appreciating a
musical note.
It is by means of the Siren that the much-disputed tonic of C will be
settled, the Continental and the English C being greatly at variance,
and even the English C having been advanced almost a tone since the time
of Handel. Much is it to be wished that Italy, the home of song, and
England, the patron of song, could unite in their tonic, instead of
having systems so widely different that an Italian singer is at a loss
with the English pitch, as is an English singer with the Italian pitch.
The Siren is even brought into the service of entomologists, enabling
them to measure by the sound the rapidity with which a flying insect
moves its wings. By means of this instrument we know the origin of the
sharp, piercing “ping” of the Gnat, and the heavy, dull boom of the
Humble-bee, both of which insects are given in the illustration.
Before taking leave of this subject, I may mention that the instrument
is called the Siren because it sings as well under water as in the air,
provided that water instead of air be driven through it.
ECHO.
Our last page will be given to the phenomenon called by the name of
ECHO, which consists in the power of solid substances, whether natural
or artificial, of reflecting the waves of sound thrown against them,
just as a mirror reflects the waves of light.
[Illustration: WHISPERING GALLERY.]
Very often the Echo is naturally formed, as shown in the illustration,
by rocks which cast back the sound--waves thrown against them. This is
the case in several parts of Dovedale in Derbyshire, where a pistol shot
is reverberated backwards and forwards in a most wonderful manner, and a
trumpet blast repeats itself over and over again.
At Walton Hall, the residence of the late C. Waterton, Esq., there is a
wonderful Echo, nearly half a mile from the house. Mr. Waterton had
discovered the Echo, which proceeded from the walls of the house, and,
having found its focus, placed on it a large stone, called the
Echo-stone. Any one sitting on this stone, and singing, speaking, or
whistling towards the house, heard every sound repeated, as if in
mockery.
The celebrated Whispering Gallery in St. Paul’s Cathedral is nothing but
an ordinary Echo, though so intensified by the process of radiation,
that the sound is transmitted from one side of the dome to the other,
just as light or heat is reflected from concave mirrors.
INDEX.
A.
Aard-vark, 182, 227
Abattis, 109
Acaleph, 15
Acorn Barnacles, 90
Acoustics, 513
Acrida viridissima, 231
Actinurus, 461
Adze, 234
Æolian Harp, 518
Aërostatics, 436
Air-gun, 77
Aloe, 252
Amentum, 502
Amphidotus cordatus, 224
Anchor, 39
Angler-fish, 91, 416
Antherozoids, 368
Ant-bear, 100
Ant-lion, 52
Anthidium manicatum, 237
Ants, 391, 409
Ants’ Nest, 214
Aphides, 391
Aphrodite aculeata, 353
Apple-parer, 456
Aquarium, 393
Archer-fish, 78
Architecture, 159
Argus Star-fish, 89
Armadillo, 189
Armour, 120
Art, 472
Artesian Well, 433
Arundinaria Schomburgkii, 28
Ascalaphus, 111
Ascidian, 497
Aspidomorpha excelsum, 198
Auger, 254
B.
Baited Traps, 97
Ball-and-socket Joint, 313
Balloon, 436
Bamboo, 28
Band Saw, 244
Barea, 147
Barometer, 444
Basket-urchin, 89
Bats, 399
Battering-ram, 153
Beak of Duck, 354
Beaver, 233
Beds, 400
Bee, 220
Beroë, 15
Bessemer Process, 299
Bicycle, 503
Binocular Microscope, 287
Birdlime, 98
Blow-gun, 75
Boat, 5
Boat-hook, 44
Boatman, 12
Boiling Water, 445
Bombardier-beetle, 156
Bombyx mori, 179
Bosjesman, 308
Bot-fly, 396
Bower, 410
Bower-birds, 410
Bowsing of Rope, 318
Brachinus crepitans, 156
Bradawl, 249
Brocken Spectre, 295
Brown-tailed Moth, 180
Brushes, 340
Buffer of Train, 369
Bullet-making Machine, 157
Bunday, 69
Burdock, 117
Burial, 419
Burying-ants, 420
Burying-beetle, 507
Buttons, 346
Buttresses, 196
C.
Cache, 397
Callipers, 274
Caltrops, 110
Camel, 424
Camera obscura, 277
Candle, 351
Carriage Spring, 363
Cassava Press, 447
Catapult, 361
Catchpoll, 104
Cathedral, 166
Centrifugal Force, 500
Cephalotus, 98
Chaff-cutter, 320
Chameleon-fly, 11
Chinese Paper Lantern, 378
Chinese Repeating Cross-bow, 365
Chinese Stink-pot, 155
Chirodota, 470
Chisel, 232
Chœtodon, 78
Chromatrope, 305
Cicada, 243, 518
Circular Saw, 247
Cistern, 422
Clam Shell, 260
Clasp, 347
Climbing-spur, 134
Cloth-dressing Machine, 339
Club, 52
Cnidæ, 371
Coffee-making Machine, 329
Coluber natrix, 106
Combs, 343
Compass, 491
Concealment, 144
Condenser, 428
Contouring-glass, 272
Coracle, 22
Cordon Saw, 244
Cork, 350
Corrugation, 480
Cossus ligniperda, 237
Crab, 261
Crab-pot, 103
Creeper, 203
Cricket, 388, 517
Crow-oyster, 348
Crushing Instruments, 320
Cuckoo-spit, 146
Culex pipiens, 9
Cupping, 330
Cuttle-bone of Sepia, 166
Cydippe, 15
D.
Daddy Long-legs, 337
Dagger, 58
Dam, 210
Dandelion Seed, 439
Decticus griseus, 231
Deer-trap, 104
Dew, 426
Diamond Drill, 459
Digging-stick, 223
Dionea muscipula, 97
Dipsacus fullonum, 339
Disguise, 147
Divers, 382
Diving-bell, 383
Diving Dress, 384
Dog-fish Skin, 265
Dome, 510
Doors and Hinges, 172
Drag, 43
Dragon-fly, 455
Dragon-fly Trachea, 376
Drainage, 492
Driver-ant, 201
Drosera, 100
Drum, 514
Dutch Rush, 264
E.
Ear, 515
Ear-trumpet, 521
Earth-worm, 44
Earwig, 261
Eaves, 184
Echeneis remora, 333
Echinococcus, 40
Echinus, 315
Echo, 525
Echo-stone, 526
Eel-pot, 103
Egg-hatching Machine, 395
Eider-duck, 401
Elastic Springs, 360
Elateridæ, 387
Electric Eel, 486
Electric Light, 488
Electric Ray, 485
Electric Tourniquet, 463
Electricity, 482
Elk, 131
Elk-yard, 131
Emperor-moth, 104
Epeira diadema, 87, 345
Equisetum, 264
Ermine-moth, 180
Escapement, 507
Ether Spray, 428
Eumenes, 311
Eye, 277
Eye of Spider, 288
F.
Fairy Martin, 169
Fall-trap, 140
Fan, 416
Feather Mail, 125
Fencers, 317
File, 263
Filter, 352, 425
Fire, 412
Fire-fly, 489
Fire-guard, 419
Fish-hook Spiculæ, 117
Fish-scales, 189
Fish-tank, 393
Fishing-frog, 91, 416
Flying Dragon, 440
Flying Frog, 441
Flying Squirrel, 440
Foot of Aard-vark, 227
Foot of Mole, 226
Foot of Mole-cricket, 226
Fork-grinders, 356
Fort, 129
Fountains, 430
Frog, 484
Furnarius fuliginosus, 310
Fur of Beaver, 186
G.
Gad-fly, 254, 406
Galleria alvearia, 151
Galleria-moth, 151
Garden Spider, 87, 345
Gecko, 334
Geometra Caterpillar, 149
Geranium, 478
Gerris, 467
Gills of Fish, 414
Gimlet, 252
Gin, 95
Girder, 193
Glow-worm, 342, 439
Gnat, 9
Goat-moth, 237
Goby, 334
Gold-tailed Moth, 180
Goose-grass, 116
Gossamer Spider, 437
Grallina Australia, 310
Grasping Tools, 258
Grass-blade, 250
Grass-snake, 106
Grass-wrack, 473
Grasshopper, 337, 388
Great Green Grasshopper, 231
Grindstone, 325
Gyrinus natator, 22
Gyroscope, 503
H.
Hammer and Anvil, 515
Hammock, 402
Hand, 450
Harpoon, 71
Heart or Hairy Urchin, 224
Hedgehog, 110
Hemerobius, 397
Hen-coop, 393
Hippopotamus, 508
Hippopotamus Tooth, 234
Hirundo Ariel, 169
Hoof of Elephant, 364
Hoof of Horse, 363
Hookah, 377
Hooks, 115, 398
Hooks and Eyes, 346
Hoop-shaver Bee, 237
House-fly, 343, 456
Human Spine, 369
Hydra, 512
Hydrant, 430
Hymedesmia, 117
Hyponomeuta padella, 180
I.
Ice, 457
Ice-house, 179
Ichneumon-fly, 174, 249, 338
Injecting Syringe, 65
Iris of Eye, 293
Ita Palm-tree, 162
J.
Janthina communis, 48
Japanese Fishing-rod, 460
Japanese Singlethorn, 124
Jaws of Crocodile, 366
Jaws of Pike, 105
Jaws of Shark, 106
Jaws of Whale, 355
K.
Kedge, 41
Kite, 500
Knee-joint, 316
Kris, 239
L.
Lace-wing Fly, 397
Lagopus vulgaris, 150
Lamp, 412
Lampern, 335
Lampetra fluviatilis, 335
Lancet, 83, 239
Lappet-moth, 149
Laurel-bottle, 358
Lazy-tongs, 454
Leaf cutter Bees, 231
Leaf-insect, 149
Leaf-rollers, 362
Leech, 335
Lighthouses, 207
Limnæa stagnalis, 6
Limpet, 245, 332
Loadstone, 490
Lobster, 261, 497
Locust, 231
Long-tailed Titmouse, 401
Lophius, 416
Low-pressure Engine, 429
Lump-sucker, 334
M.
Maelström, 1
Magdeburg Hemispheres, 331
Magic Lantern, 294
Magnetic Respirator, 356
Main Gauche, 73
Mangle, 324
Mangrove-tree, 143
Manuring, 492
Mare’s Tail, 264
Mason Wasp, 170
Mat, 404
Meadow Orchis, 100
Measure, 267
Medusa, 372, 512
Megachile, 231
Metronome, 506
Microgaster alvearius, 174
Microgaster glomeratus, 174
Milk, 390
Mines, 443
Mining, 430
Misericorde, 120
Mole, 496
Mole-cricket, 227
Mont Cenis Tunnel, 267
Mop, 502
Mortar, 217
Moselekatze, 162
Moss, 371
Mountains, 216
Mouse-trap, 97
Movable Gas-lamp, 376
Mud-patten, 466
Mud Walls, 181
Multiplying-glass, 288
Muscles of Leg, 449
Mussel-shell, 35, 259
Myrapetra scutellaris, 181
Myrmeleo, 52
Myrmica Kirbyi, 184
N.
Nature-printing, 475
Nautilus, 2, 464
Needle-gun, 367
Nemertes Borlasii, 93
Nerves, 486
Net, 85
Northern Crown, 297
Norton Tubes, 433
Notonecta glauca, 13
Nshiego Mbouvé, 160
Nut-crackers, 321
Nuthatch, 256
O.
Octopus, 463
Odynerus murarius, 170
Œstrus bovis, 254
Ophion, 174
Optics, 276
Orchis morio, 100
Oscillation, 504
Ostracion, 122
Orang-outan, 161
Oven-bird, 310
Owl’s Eye, 284
P.
Paddle-wood Tree, 198
Paint, 219
Palm-leaf, 418
Paper, 472
Parachute, 438
Parasol, 407
Pea-shooter, 74
Pelecinus, 338
Pelicans, 393
Pelopœus, 312
Pendulum, 505
Pensile Oriole, 402
Perfume Spray, 428
Periwinkle, 245
Phantasmascope, 305
Philetærus socius, 135
Pholas dactylus, 200
Phryganea, 192
Physa fontinalis, 8
Physalis pelagicus, 46
Pichiciago, 123
Piddock, 200
Pied Grallina, 310
Pill Millipede, 123
Pincers, 258
Pinna pectinata, 35
Pinna-shell, 35
Pistolograph, 361
Pitfall, 50
Plane, 235, 250
Pneumatic Peg, 330
Poison, 62
Polar Bear, 137
Polistes, 481
Polynoe, 71
Porches, 183
Porcupine, 110
Porcupine Ant-eater, 110
Porthesia auriflua, 180
Porthesia chrysorrhœa, 180
Portuguese Man-of-war, 46, 372
Pouch-shell, 8
Pressure of Atmosphere, 329
Printing-press, 317
Proboscis of Fly, 379
Processionary Moth, 180
Projectiles, 74
Propolis, 220
Pseudoscope, 287
Ptarmigan, 150
Pucunha, 76
Puff and Dart, 75, 351
Pulley, 452
Pyramids, 216
Q.
Quilt Armour, 126
R.
Radius, 194
Rain-cloud, 429
Ranjows, 109
Rat-tail Maggots, 385
Rattan, 204
Razor, 236
Receiver of Air-pump, 511
Reduvius personatus, 146
Reed, 518
Reverted Spikes, 102
Ribbon Saw, 244
Ring and Staple, 415
Ringed Tissues, 378
Robber-crab, 405
Rocket, 462
Rod and Line, 90
Rolling-mill, 322
Rosemary, 408
S.
Sabella, 218
Saddle-back, 348
Sailing Raft, 5
Salad-dressing Bottle, 511
Sand-paper, 265
Saturnia pavonia minor, 104
Saw, 239
Saw-fly, 241
Sawyer-beetle, 248
Scale Armour, 123
Scales of Butterfly’s Wings, 187
Scaling-fork, 133
Scarabæus, 494
Scissors, 228
Screw, 498
Sea-anemone, 8
Sea-basket, 89
Sea-mouse, 353
Sea-urchin, 315
Seed-drills, 336
Sepia officinalis, 167
Serpula, 44, 135, 219, 352
Sewage, 496
Sewing, 406
Shark-tooth Sword, 56
Shears, 228
Sheep-fly, 396
Shell of Tortoise, 188
Ship-worm, 200
Short-tailed Manis, 124, 188
Sialis armata, 275
Siamese Link, 448
Silkworm, 158
Silkworm Cocoon, 179
Siren, 523
Sirex gigas, 252
Skidor, 466
Skip-jack Beetle, 387
Skull, 210, 511
Slates, 188
Sling, 502
Sloth, 398
Slug, 245
Smoke-jack, 499
Snow-house of Esquimaux, 163
Snow-house of Seal, 163
Snow-shoe, 464
Spade, 223
Spear, 58
Spectroscope, 297
Spider, 509
Spider-crab, 147
Spiked Defences, 107
Spiracles of Fly, 357
Spiral, 498
Spiral Spring, 371
Spiral Tissues, 375
Spirit-level, 271
Spokeshave, 236
Spout-hole, 434
Sprat-sucker, 71
Spring, 430
Spring-bow, 142
Spring-gun, 142
Spring-jack, 386
Spring Solitaire, 371
Spring-tails, 388
Spring-trap, 95
Squirrel, 456
Stag-beetle, 248
Star-fish, 332
Steam-blast, 443
Steelyard, 450
Stereoscope, 286
Stereotype, 479
Stethoscope, 522
Stickleback, 218
Still, 425
Stinging Jelly-fish, 372
Stinging-nettle, 67
Stipple, 477
Stoat, 150
Stone-fly, 192
Stopper, 350
Stove, 413
Stratiomys, 11
Stratiomys chamæleon, 11
String, 515
Subterranean Dwelling, 213
Suckers of Cuttle-fish, 332
Suckers of Water-beetle, 332
Sucking Eggs, 445
Sucking-fish, 333
Sucking Sugar-cane, 445
Sumpitan, 75
Sundew, 100
Surgical Cradle, 405
Suspension-bridge, 202
Swallow-tailed Butterfly, 468
Sword, 56
Sword-grass, 57
Synapta, 40, 470
Synovia, 454
T.
Tachina, 172
Tail of Scorpion, 66
Tailor-bird, 406
Tearing Weapons, 112
Teazle, 339
Teeth, 327
Telegraph, 487
Terebella, 218
Teredo, 200
Termite, 153, 182, 394
Thaumatrope, 302
Thigh-bone, 314
Thornback-crab, 147
Throwing-stick, 79
Ties, 194
Tiger-beetle, 134
Tiger-claw, 112
Tiger-moth, 403
Tiles, 187
Tillage, 492
Tipula, 337
Toggle, 316
Tools, 222
Tools of Measurement, 267
Top, 503
Torpedo, 485
Tortoise, 229
Toucan, 346
Trachea of Animals, 380
Trachea of Insects, 376
Trap-door Spider, 175
Traveller’s Tree, 423
Tree-caddis, 111
Trench, 150
Trichiosoma lucorum, 242
Tripod Wheel-bearer, 461
Triquetra, 219
Troglodytes calvus, 160
Trombone, 520
Trunk-fish, 122
Trypoxylon aurifrons, 312
Tunnel, 168, 199
Turbine Pump, 497
Turkish Bath, 426
Turtle, 229
U.
Ulna, 194
Umbrella, 407
Useful Arts, 308
V.
Vallisneria Plant, 38
Varnish, 219
Velella, 2
Venus Fly-trap, 97
Vertebræ of Snake, 314
Victoria Regia, 196
Violet Snail, 48
Voltaic Pile, 484
W.
Walls, 177
Walrus, 41, 136
Waraus, 162
Wart-biter, 231
Wasp, 474
Wasp-comb, 167
Water-boatman, 13
Water-fall, 431
Water-gnat, 467
Water-lily, 382
Water Main, 497
Water-ram, 434
Water-snail, 6
Water-spider, 383
Water-tank, 423
Water Telescope, 291
Water Turbine, 463
Wax, 220
Wax-moth, 151
Weaver-bird, 169, 185
Webbed Feet, 467
Wet-bulb Thermometer, 428
Wheat Straw, 27
Wheel, 469
Wheel Animalculæ, 306
Whelk, 245
Whirlwig-beetle, 22, 292
Whispering Gallery, 626
Wind, 442
Window, 190
Woodpecker, 256
Woolly Bear, 110
Wurble-fly, 396
Z.
Zarabatana, 76
Zoetrope, 305
Zostera marina, 473
* * * * *
THE END.
PRINTED BY J. S. VIRTUE AND CO. LIMITED, CITY ROAD, LONDON.
* * * * *
Typographical errors corrected by the etext transcriber:
Bombadier-beetle=> Bombardier-beetle {pg 144}
very ong after=> very long after {pg 262}
the Multipying-glass=> the Multiplying-glass {pg 290}
fills the air=> fill the air {pg 356}
cook their flood=> cook their food {pg 412}
If the hand move towards=> If the hand move towards {pg 444}
protecting the yelk=> protecting the yolk {pg 511}
*** End of this LibraryBlog Digital Book "Nature's Teachings - Human Invention Anticipated by Nature" ***
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