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Title: The Beauties of Nature - and the Wonders of the World We Live In
Author: Lubbock, John, Sir, 1834-1913
Language: English
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THE BEAUTIES OF NATURE
[Illustration: _Frontispiece._
GROUP OF BEECHES, BURNHAM. _Page 167._]
THE
BEAUTIES OF NATURE
AND THE
WONDERS OF THE WORLD
WE LIVE IN
BY
THE RIGHT HON.
SIR JOHN LUBBOCK, BART., M.P.
F.R.S., D.C.L., LL.D.
New York
MACMILLAN AND CO.
AND LONDON
1892
_All rights reserved_
COPYRIGHT, 1892,
BY MACMILLAN AND CO.
TYPOGRAPHY BY J. S. CUSHING & CO., BOSTON, U.S.A.
PRESSWORK BY BERWICK & SMITH, BOSTON, U.S.A.
CONTENTS
CHAPTER I
PAGE
INTRODUCTION 1
Beauty and Happiness 3
The Love of Nature 5
Enjoyment of Scenery 14
Scenery of England 19
Foreign Scenery 21
The Aurora 33
The Seasons 34
CHAPTER II
ON ANIMAL LIFE 39
Love of Animals 41
Growth and Metamorphoses 43
Rudimentary Organs 45
Modifications 48
Colour 50
Communities of Animals 57
Ants 58
CHAPTER III
ON ANIMAL LIFE--_continued_ 71
Freedom of Animals 73
Sleep 78
Senses 84
Sense of Direction 93
Number of Species 96
Importance of the Smaller Animals 97
Size of Animals 100
Complexity of Animal Structure 101
Length of Life 102
On Individuality 104
Animal Immortality 112
CHAPTER IV
ON PLANT LIFE 115
Structure of Flowers 128
Insects and Flowers 134
Past History of Flowers 136
Fruits and Seeds 137
Leaves 138
Aquatic Plants 144
On Hairs 148
Influence of Soil 151
On Seedlings 152
Sleep of Plants 152
Behaviour of Leaves in Rain 155
Mimicry 156
Ants and Plants 156
Insectivorous Plants 158
Movements of Plants 159
Imperfection of our Knowledge 163
CHAPTER V
WOODS AND FIELDS 165
Fairy Land 172
Tropical Forests 179
Structure of Trees 185
Ages of Trees 188
Meadows 192
Downs 194
CHAPTER VI
MOUNTAINS 201
Alpine Flowers 205
Mountain Scenery 206
The Afterglow 213
The Origin of Mountains 214
Glaciers 227
Swiss Mountains 232
Volcanoes 236
Origin of Volcanoes 243
CHAPTER VII
WATER 249
Rivers and Witchcraft 251
Water Plants 252
Water Animals 253
Origin of Rivers 255
The Course of Rivers 256
Deltas 272
CHAPTER VIII
RIVERS AND LAKES 277
On the Directions of Rivers 279
The Conflicts and Adventures of Rivers 301
On Lakes 312
On the Configuration of Valleys 323
CHAPTER IX
THE SEA 335
The Sea Coast 337
Sea Life 344
The Ocean Depths 351
Coral Islands 358
The Southern Skies 365
The Poles 367
CHAPTER X
THE STARRY HEAVENS 373
The Moon 377
The Sun 382
The Planets 387
Mercury 388
Venus 390
The Earth 391
Mars 392
The Minor Planets 393
Jupiter 394
Saturn 395
Uranus 396
Neptune 397
Origin of the Planetary System 398
Comets 401
Shooting Stars 406
The Stars 410
Nebulæ 425
ILLUSTRATIONS
FIG. PAGE
1. Larva of Choerocampa porcellus 53
2. Bougainvillea fruticosa; natural size. (After Allman) 107
3. Do. do. magnified 108
4. Do. do. Medusa-form 109
5. Medusa aurita, and progressive stages of development.
(After Steenstrup) 110
6. White Dead-nettle 124
7. Do. 125
8. Do. 125
9. Salvia 127
10. Do. 127
11. Do. 127
12. Primrose 131
13. Do. 131
14. Arum 135
15. Twig of Beech 140
16. Arrangement of leaves in Acer platanoides 142
17. Diagram to illustrate the formation of Mountain Chains 216
18. Section across the Jura from Brenets to Neuchâtel. (After Jaccard) 219
19. Section from the Spitzen across the Brunnialp, and the
Maderanerthal. (After Heim) 221
20. Glacier of the Blümlis Alp. (After Reclus) 228
21. Cotopaxi. (After Judd) 237
22. Lava Stream. (After Judd) 239
23. Stromboli, viewed from the north-west, April 1874. (After Judd) 242
24. Upper Valley of St. Gotthard 257
25. Section of a river valley. The dotted line shows a slope or
talus of debris 260
26. Valley of the Rhone, with the waterfall of Sallenches, showing
a talus of debris 261
27. Section across a valley. _A_, present river valley; _B_, old
river terrace 262
28. Diagram of an Alpine valley, showing a river cone. Front view 263
29. Diagram of an Alpine valley, showing a river cone. Lateral view 265
30. Map of the Valais near Sion 266
31. View in the Rhone Valley, showing a lateral cone 267
32. Do. showing the slope of a river cone 268
33. Shore of the Lake of Geneva, near Vevey 269
34. View in the district of the Broads, Norfolk 271
35. Delta of the Po 273
36. Do. Mississippi 274
37. Map of the Lake District 281
38. Section of the Weald of Kent, _a, a_, Upper Cretaceous strata,
chiefly Chalk, forming the North and South Downs; _b, b_, Escarpment of
Lower Greensand, with a valley between it and the Chalk; _c, c_, Weald
Clay, forming plains; _d_, Hills formed of Hastings Sand and Clay. The
Chalk, etc., once spread across the country, as shown in the dotted
lines 283
39. Map of the Weald of Kent 284
40. Sketch Map of the Swiss Rivers 291
41. Diagram in illustration of mountain structure 296
42. Sketch Map of the Aar and its tributaries 299
43. River system round Chur, as it used to be 308
44. River system round Chur, as it is 309
45. River system of the Maloya 311
46. Final slope of a river 317
47. Do. do. with a lake 318
48. Diagrammatic section of a valley (exaggerated). _R R_, rocky basis of
a valley; _A A_, sedimentary strata; _B_, ordinary level of river;
_C_, flood level 329
49. Whitsunday Island. (After Darwin) 359
50. A group of Lunar volcanoes; Maurolycus, Barocius, etc.
(After Judd) 380
51. Orbits of the inner Planets. (After Ball) 388
52. Relative distances of the Planets from the Sun. (After Ball) 389
53. Saturn, with the surrounding series of rings. (After Lockyer) 395
54. The Parallactic Ellipse. (After Ball) 413
55. Displacement of the hydrogen line in the spectrum of Rigel.
(After Clarke) 416
PLATES
BURNHAM BEECHES _Frontispiece_
WINDSOR CASTLE. (From a drawing by J. Finnemore) _To face page_ 13
AQUATIC VEGETATION, RIO. (Published by Spooner and Co.) 145
TROPICAL FOREST, WEST INDIES. (After Kingsley) 179
SUMMIT OF MONT BLANC 203
THE MER DE GLACE, MONT BLANC 229
RYDAL WATER. (From a photograph by Frith and Co., published by
Spooner and Co.) 247
WINDERMERE 253
VIEW IN THE VALAIS BELOW ST. MAURICE 264
VIEW UP THE VALAIS FROM THE LAKE OF GENEVA 268
THE LAND'S END. (From a photograph by Frith and Co., published by
Spooner and Co.) 334
VIEW OF THE MOON NEAR THE THIRD QUARTER. (From a photograph by Prof.
Draper) 371
CHAPTER I
INTRODUCTION
If any one gave you a few acres, you would say that you had
received a benefit; can you deny that the boundless extent of
the earth is a benefit? If any one gave you money, you would
call that a benefit. God has buried countless masses of gold
and silver in the earth. If a house were given you, bright with
marble, its roof beautifully painted with colours and gilding,
you would call it no small benefit. God has built for you a
mansion that fears no fire or ruin ... covered with a roof
which glitters in one fashion by day, and in another by
night.... Whence comes the breath you draw; the light by which
you perform the actions of your life? the blood by which your
life is maintained? the meat by which your hunger is
appeased?... The true God has planted, not a few oxen, but all
the herds on their pastures throughout the world, and furnished
food to all the flocks; he has ordained the alternation of
summer and winter ... has invented so many arts and varieties
of voice, so many notes to make music.... We have implanted in
us the seed of all ages, of all arts; and God our Master brings
forth our intellects from obscurity.--SENECA.
CHAPTER I
INTRODUCTION
The world we live in is a fairyland of exquisite beauty, our very
existence is a miracle in itself, and yet few of us enjoy as we might,
and none as yet appreciate fully, the beauties and wonders which
surround us. The greatest traveller cannot hope even in a long life to
visit more than a very small part of our earth, and even of that which
is under our very eyes how little we see!
What we do see depends mainly on what we look for. When we turn our eyes
to the sky, it is in most cases merely to see whether it is likely to
rain. In the same field the farmer will notice the crop, geologists the
fossils, botanists the flowers, artists the colouring, sportsmen the
cover for game. Though we may all look at the same things, it does not
at all follow that we should see them.
It is good, as Keble says, "to have our thoughts lift up to that world
where all is beautiful and glorious,"--but it is well to realise also
how much of this world is beautiful. It has, I know, been maintained, as
for instance by Victor Hugo, that the general effect of beauty is to
sadden. "Comme la vie de l'homme, même la plus prospère, est toujours au
fond plus triste que gaie, le ciel sombre nous est harmonieux. Le ciel
éclatant et joyeux nous est ironique. La Nature triste nous ressemble et
nous console; la Nature rayonnante, magnifique, superbe ... a quelque
chose d'accablant."[1]
This seems to me, I confess, a morbid view. There are many no doubt on
whom the effect of natural beauty is to intensify feeling, to deepen
melancholy, as well as to raise the spirits. As Mrs. W. R. Greg in her
memoir of her husband tells us: "His passionate love for nature, so
amply fed by the beauty of the scenes around him, intensified the
emotions, as all keen perception of beauty does, but it did not add to
their joyousness. We speak of the pleasure which nature and art and
music give us; what we really mean is that our whole being is quickened
by the uplifting of the veil. Something passes into us which makes our
sorrows more sorrowful, our joys more joyful,--our whole life more
vivid. So it was with him. The long solitary wanderings over the hills,
and the beautiful moonlight nights on the lake served to make the
shadows seem darker that were brooding over his home."
But surely to most of us Nature when sombre, or even gloomy, is soothing
and consoling; when bright and beautiful, not only raises the spirits,
but inspires and elevates our whole being--
Nature never did betray
The heart that loved her; 'tis her privilege,
Through all the years of this our life, to lead
From joy to joy: for she can so inform
The mind that is within us, so impress
With quietness and beauty, and so feed
With lofty thoughts, that neither evil tongues,
Rash judgments, nor the sneers of selfish men,
Nor greetings where no kindness is, nor all
The dreary intercourse of daily life,
Shall e'er prevail against us, or disturb
Our cheerful faith, that all which we behold
Is full of blessings.[2]
Kingsley speaks with enthusiasm of the heaths and moors round his home,
"where I have so long enjoyed the wonders of nature; never, I can
honestly say, alone; because when man was not with me, I had companions
in every bee, and flower and pebble; and never idle, because I could not
pass a swamp, or a tuft of heather, without finding in it a fairy tale
of which I could but decipher here and there a line or two, and yet
found them more interesting than all the books, save one, which were
ever written upon earth."
Those who love Nature can never be dull. They may have other
temptations; but at least they will run no risk of being beguiled, by
ennui, idleness, or want of occupation, "to buy the merry madness of an
hour with the long penitence of after time." The love of Nature, again,
helps us greatly to keep ourselves free from those mean and petty cares
which interfere so much with calm and peace of mind. It turns "every
ordinary walk into a morning or evening sacrifice," and brightens life
until it becomes almost like a fairy tale.
In the romances of the Middle Ages we read of knights who loved, and
were loved by, Nature spirits,--of Sir Launfal and the Fairy Tryamour,
who furnished him with many good things, including a magic purse, in
which
As oft as thou puttest thy hand therein
A mark of gold thou shalt iwinne,
as well as protection from the main dangers of life. Such times have
passed away, but better ones have come. It is not now merely the few,
who are so favoured. All those who love Nature she loves in return, and
will richly reward, not perhaps with the good things, as they are
commonly called, but with the best things, of this world; not with money
and titles, horses and carriages, but with bright and happy thoughts,
contentment and peace of mind.
Happy indeed is the naturalist: to him the seasons come round like old
friends; to him the birds sing: as he walks along, the flowers stretch
out from the hedges, or look up from the ground, and as each year fades
away, he looks back on a fresh store of happy memories.
Though we can never "remount the river of our years," he who loves
Nature is always young. But what is the love of Nature? Some seem to
think they show a love of flowers by gathering them. How often one finds
a bunch of withered blossoms on the roadside, plucked only to be thrown
away! Is this love of Nature? It is, on the contrary, a wicked waste,
for a waste of beauty is almost the worst waste of all.
If we could imagine a day prolonged for a lifetime, or nearly so, and
that sunrise and sunset were rare events which happened but a few times
to each of us, we should certainly be entranced by the beauty of the
morning and evening tints. The golden rays of the morning are a fortune
in themselves, but we too often overlook the loveliness of Nature,
because it is constantly before us. For "the senseless folk," says King
Alfred,
is far more struck
At things it seldom sees.
"Well," says Cicero, "did Aristotle observe, 'If there were men whose
habitations had been always underground, in great and commodious houses,
adorned with statues and pictures, furnished with everything which they
who are reputed happy abound with; and if, without stirring from thence,
they should be informed of a certain divine power and majesty, and,
after some time, the earth should open, and they should quit their dark
abode to come to us; where they should immediately behold the earth, the
seas, the heavens; should consider the vast extent of the clouds and
force of the winds; should see the sun, and observe his grandeur and
beauty, and also his creative power, inasmuch as day is occasioned by
the diffusion of his light through the sky; and when night has obscured
the earth, they should contemplate the heavens bespangled and adorned
with stars; the surprising variety of the moon, in her increase and
wane; the rising and setting of all the stars, and the inviolable
regularity of their courses; when,' says he, 'they should see these
things, they would undoubtedly conclude that there are Gods, and that
these are their mighty works.'"[3]
Is my life vulgar, my fate mean,
Which on such golden memories can lean?[4]
At the same time the change which has taken place in the character of
our religion has in one respect weakened the hold which Nature has upon
our feelings. To the Greeks--to our own ancestors,--every River or
Mountain or Forest had not only its own special Deity, but in some sense
was itself instinct with life. They were not only peopled by Nymphs and
Fauns, Elves and Kelpies, were not only the favourite abodes of Water,
Forest, or Mountain Spirits, but they had a conscious existence of their
own.
In the Middle Ages indeed, these spirits were regarded as often
mischievous, and apt to take offence; sometimes as essentially
malevolent--even the most beautiful, like the Venus of Tannhäuser, being
often on that very account all the more dangerous; while the Mountains
and Forests, the Lakes and Seas, were the abodes of hideous ghosts and
horrible monsters, of Giants and Ogres, Sorcerers and Demons. These
fears, though vague, were none the less extreme, and the judicial
records of the Middle Ages furnish only too conclusive evidence that
they were a terrible reality. The light of Science has now happily
dispelled these fearful nightmares.
Unfortunately, however, as men have multiplied, their energies have
hitherto tended, not to beautify, but to mar. Forests have been cut
down, and replaced by flat fields in geometrical squares, or on the
continent by narrow strips. Here and there indeed we meet with oases, in
which beauty has not been sacrificed to profit, and it is then happily
found that not only is there no loss, but the earth seems to reward even
more richly those who treat her with love and respect.
Scarcely any part of the world affords so great a variety in so small an
area as our own island. Commencing in the south, we have first the blue
sea itself, the pebbly beaches, the white chalk cliffs of Kent, the
tinted sands of Alum Bay, the Red Sandstone of Devonshire, Granite and
Gneiss in Cornwall: inland we have the chalk Downs and clear streams,
the well-wooded weald and the rich hop gardens; farther westwards the
undulating gravelly hills, and still farther the granite tors: in the
centre of England we have to the east the Norfolk Broads and the Fens;
then the fertile Midlands, the cornfields, rich meadows, and large oxen;
and to the west the Welsh mountains; farther north the Yorkshire Wolds,
the Lancashire hills, the Lakes of Westmoreland; lastly, the swelling
hills, bleak moors, and picturesque castles of Northumberland and
Cumberland.
There are of course far larger rivers, but perhaps none lovelier than
The crystal Thamis wont to glide
In silver channel, down along the lee,[5]
[Illustration: WINDSOR CASTLE.
_To face page 13._]
by lawns and parks, meadows and wooded banks, dotted with country houses
and crowned by Windsor Castle itself (see Frontispiece). By many
Scotland is considered even more beautiful.
And yet too many of us see nothing in the fields but sacks of wheat, in
the meadows but trusses of hay, and in woods but planks for houses, or
cover for game. Even from this more prosaic point of view, how much
there is to wonder at and admire, in the wonderful chemistry which
changes grass and leaves, flowers and seeds, into bread and milk, eggs
and cream, butter and honey!
Almost everything, says Hamerton, "that the Peasant does, is lifted
above vulgarity by ancient, and often sacred, associations." There is,
indeed, hardly any business or occupation with reference to which the
same might not be said. The triviality or vulgarity does not depend on
what we do, but on the spirit in which it is done. Not only the regular
professions, but every useful occupation in life, however humble, is
honourable in itself, and may be pursued with dignity and peace.
Working in this spirit we have also the satisfaction of feeling that, as
in some mountain track every one who takes the right path, seems to make
the way clearer for those who follow; so may we also raise the
profession we adopt, and smooth the way for those who come after us.
But, even for those who are not Agriculturists, it must be admitted that
the country has special charms. One perhaps is the continual change.
Every week brings some fresh leaf or flower, bird or insect. Every month
again has its own charms and beauty. We sit quietly at home and Nature
decks herself for us.
In truth we all love change. Some think they do not care for it, but I
doubt if they know themselves.
"Not," said Jefferies, "for many years was I able to see why I went the
same round and did not care for change. I do not want change: I want the
same old and loved things, the same wild flowers, the same trees and
soft ash-green; the turtle-doves, the blackbirds, the coloured
yellow-hammer sing, sing, singing so long as there is light to cast a
shadow on the dial, for such is the measure of his song, and I want
them in the same place. Let me find them morning after morning, the
starry-white petals radiating, striving upwards up to their ideal. Let
me see the idle shadows resting on the white dust; let me hear the
humble-bees, and stay to look down on the yellow dandelion disk. Let me
see the very thistles opening their great crowns--I should miss the
thistles; the reed grasses hiding the moor-hen; the bryony bine, at
first crudely ambitious and lifted by force of youthful sap straight
above the hedgerow to sink of its weight presently and progress with
crafty tendrils; swifts shot through the air with outstretched wings
like crescent-headed shaftless arrows darted from the clouds; the
chaffinch with a feather in her bill; all the living staircase of the
spring, step by step, upwards to the great gallery of the summer, let me
watch the same succession year by year."
After all then he did enjoy the change and the succession.
Kingsley again in his charming prose idyll "My Winter Garden" tries to
persuade himself that he was glad he had never travelled, "having never
yet actually got to Paris." Monotony, he says, "is pleasant in itself;
morally pleasant, and morally useful. Marriage is monotonous; but there
is much, I trust, to be said in favour of holy wedlock. Living in the
same house is monotonous; but three removes, say the wise, are as bad as
a fire. Locomotion is regarded as an evil by our Litany. The Litany, as
usual, is right. 'Those who travel by land or sea' are to be objects of
our pity and our prayers; and I do pity them. I delight in that same
monotony. It saves curiosity, anxiety, excitement, disappointment, and a
host of bad passions."
But even as he writes one can see that he does not convince himself.
Possibly, he admits, "after all, the grapes are sour"; and when some
years after he did travel, how happy he was! At last, he says,
triumphantly, "At last we too are crossing the Atlantic. At last the
dream of forty years, please God, would be fulfilled, and I should see
(and happily not alone), the West Indies and the Spanish Main. From
childhood I had studied their Natural History, their Charts, their
Romances; and now, at last, I was about to compare books with facts, and
judge for myself of the reported wonders of the Earthly Paradise."
No doubt there is much to see everywhere. The Poet and the Naturalist
find "tropical forests in every square foot of turf." It may even be
better, and especially for the more sensitive natures, to live mostly in
quiet scenery, among fields and hedgerows, woods and downs; but it is
surely good for every one, from time to time, to refresh and strengthen
both mind and body by a spell of Sea air or Mountain beauty.
On the other hand we are told, and told of course with truth, that
though mountains may be the cathedrals of Nature, they are generally
remote from centres of population; that our great cities are grimy,
dark, and ugly; that factories are creeping over several of our
counties, blighting them into building ground, replacing trees by
chimneys, and destroying almost every vestige of natural beauty.
But if this be true, is it not all the more desirable that our people
should have access to pictures and books, which may in some small
degree, at any rate, replace what they have thus unfortunately lost? We
cannot all travel; and even those who can, are able to see but a small
part of the world. Moreover, though no one who has once seen, can ever
forget, the Alps, the Swiss lakes, or the Riviera, still the
recollection becomes less vivid as years roll on, and it is pleasant,
from time to time, to be reminded of their beauties.
There is one other advantage not less important. We sometimes speak as
if to visit a country, and to see it, were the same thing. But this is
not so. It is not every one who can see Switzerland like a Ruskin or a
Tyndall. Their beautiful descriptions of mountain scenery depend less on
their mastery of the English language, great as that is, than on their
power of seeing what is before them. It has been to me therefore a
matter of much interest to know which aspects of Nature have given the
greatest pleasure to, or have most impressed, those who, either from
wide experience or from their love of Nature, may be considered best
able to judge. I will begin with an English scene from Kingsley. He is
describing his return from a day's trout-fishing:--
"What shall we see," he says, "as we look across the broad, still, clear
river, where the great dark trout sail to and fro lazily in the sun?
White chalk fields above, quivering hazy in the heat. A park full of
merry hay-makers; gay red and blue waggons; stalwart horses switching
off the flies; dark avenues of tall elms; groups of abele, 'tossing
their whispering silver to the sun'; and amid them the house,--a great
square red-brick mass, made light and cheerful though by quoins and
windows of white Sarsden stone, with high peaked French roofs, broken by
louvres and dormers, haunted by a thousand swallows and starlings. Old
walled gardens, gay with flowers, shall stretch right and left. Clipt
yew alleys shall wander away into mysterious glooms, and out of their
black arches shall come tripping children, like white fairies, to laugh
and talk with the girl who lies dreaming and reading in the hammock
there, beneath the black velvet canopy of the great cedar tree, like
some fair tropic flower hanging from its boughs; and we will sit down,
and eat and drink among the burdock leaves, and then watch the quiet
house, and lawn, and flowers, and fair human creatures, and shining
water, all sleeping breathless in the glorious light beneath the
glorious blue, till we doze off, lulled by the murmur of a thousand
insects, and the rich minstrelsy of nightingale and blackcap, thrush and
dove.
"Peaceful, graceful, complete English country life and country houses;
everywhere finish and polish; Nature perfected by the wealth and art of
peaceful centuries! Why should I exchange you, even for the sight of all
the Alps?"
Though Jefferies was unfortunately never able to travel, few men have
loved Nature more devotedly, and speaking of his own home he expresses
his opinion that: "Of all sweet things there is none so sweet as fresh
air--one great flower it is, drawn round about; over, and enclosing us,
like Aphrodite's arms; as if the dome of the sky were a bell-flower
drooping down over us, and the magical essence of it filling all the
room of the earth. Sweetest of all things is wild-flower air. Full of
their ideal the starry flowers strained upwards on the bank, striving to
keep above the rude grasses that push by them; genius has ever had such
a struggle. The plain road was made beautiful by the many thoughts it
gave. I came every morning to stay by the star-lit bank."
Passing to countries across the ocean, Humboldt tells us that: "If I
might be allowed to abandon myself to the recollection of my own distant
travels, I would instance, amongst the most striking scenes of nature,
the calm sublimity of a tropical night, when the stars, not sparkling,
as in our northern skies, shed their soft and planetary light over the
gently heaving ocean; or I would recall the deep valleys of the
Cordilleras, where the tall and slender palms pierce the leafy veil
around them, and waving on high their feathery and arrow-like branches,
form, as it were, 'a forest above a forest'; or I would describe the
summit of the Peak of Teneriffe, when a horizon layer of clouds,
dazzling in whiteness, has separated the cone of cinders from the plain
below, and suddenly the ascending current pierces the cloudy veil, so
that the eye of the traveller may range from the brink of the crater,
along the vine-clad slopes of Orotava, to the orange gardens and banana
groves that skirt the shore. In scenes like these, it is not the
peaceful charm uniformly spread over the face of nature that moves the
heart, but rather the peculiar physiognomy and conformation of the land,
the features of the landscape, the ever-varying outline of the clouds,
and their blending with the horizon of the sea, whether it lies spread
before us like a smooth and shining mirror, or is dimly seen through the
morning mist. All that the senses can but imperfectly comprehend, all
that is most awful in such romantic scenes of nature, may become a
source of enjoyment to man, by opening a wide field to the creative
power of his imagination. Impressions change with the varying movements
of the mind, and we are led by a happy illusion to believe that we
receive from the external world that with which we have ourselves
invested it."
Humboldt also singles out for especial praise the following description
given of Tahiti by Darwin[6]:--
"The land capable of cultivation is scarcely in any part more than a
fringe of low alluvial soil, accumulated round the base of mountains,
and protected from the waves of the sea by a coral reef, which encircles
at a distance the entire line of coast. The reef is broken in several
parts so that ships can pass through, and the lake of smooth water
within, thus affords a safe harbour, as well as a channel for the native
canoes. The low land which comes down to the beach of coral sand is
covered by the most beautiful productions of the inter-tropical regions.
In the midst of bananas, orange, cocoa-nut, and breadfruit trees, spots
are cleared where yams, sweet potatoes, sugar-cane, and pine-apples are
cultivated. Even the brushwood is a fruit tree, namely, the guava,
which from its abundance is as noxious as a weed. In Brazil I have often
admired the contrast of varied beauty in the banana, palm, and orange
tree; here we have in addition the breadfruit tree, conspicuous from its
large, glossy, and deeply digitated leaf. It is admirable to behold
groves of a tree, sending forth its branches with the force of an
English Oak, loaded with large and most nutritious fruit. However little
on most occasions utility explains the delight received from any fine
prospect, in this case it cannot fail to enter as an element in the
feeling. The little winding paths, cool from the surrounding shade, led
to the scattered houses; and the owners of these everywhere gave us a
cheerful and most hospitable reception."
Darwin himself has told us, after going round the world that "in calling
up images of the past, I find the plains of Patagonia frequently cross
before my eyes; yet these plains are pronounced by all to be most
wretched and useless. They are characterised only by negative
possessions; without habitations, without water, without trees, without
mountains, they support only a few dwarf plants. Why then--and the case
is not peculiar to myself--have these arid wastes taken so firm
possession of my mind? Why have not the still more level, the greener
and more fertile pampas, which are serviceable to mankind, produced an
equal impression? I can scarcely analyse these feelings, but it must be
partly owing to the free scope given to the imagination. The plains of
Patagonia are boundless, for they are scarcely practicable, and hence
unknown; they bear the stamp of having thus lasted for ages, and there
appears no limit to their duration through future time. If, as the
ancients supposed, the flat earth was surrounded by an impassable
breadth of water, or by deserts heated to an intolerable excess, who
would not look at these last boundaries to man's knowledge with deep but
ill-defined sensations?"
Hamerton, whose wide experience and artistic power make his opinion
especially important, says:--
"I know nothing in the visible world that combines splendour and purity
so perfectly as a great mountain entirely covered with frozen snow and
reflected in the vast mirror of a lake. As the sun declines, its
thousand shadows lengthen, pure as the cold green azure in the depth of
a glacier's crevasse, and the illuminated snow takes first the tender
colour of a white rose, and then the flush of a red one, and the sky
turns to a pale malachite green, till the rare strange vision fades into
ghastly gray, but leaves with you a permanent recollection of its too
transient beauty."[7]
Wallace especially, and very justly, praises the description of tropical
forest scenery given by Belt in his charming _Naturalist in
Nicaragua_:--
"On each side of the road great trees towered up, carrying their crowns
out of sight amongst a canopy of foliage, and with lianas hanging from
nearly every bough, and passing from tree to tree, entangling the giants
in a great network of coiling cables. Sometimes a tree appears covered
with beautiful flowers which do not belong to it, but to one of the
lianas that twines through its branches and sends down great rope-like
stems to the ground. Climbing ferns and vanilla cling to the trunks, and
a thousand epiphytes perch themselves on the branches. Amongst these are
large arums that send down long aerial roots, tough and strong, and
universally used instead of cordage by the natives. Amongst the
undergrowth several small species of palms, varying in height from two
to fifteen feet, are common; and now and then magnificent tree ferns
send off their feathery crowns twenty feet from the ground to delight
the sight by their graceful elegance. Great broad-leaved heliconias,
leathery melastomæ, and succulent-stemmed, lop-sided leaved and
flesh-coloured begonias are abundant, and typical of tropical American
forests; but not less so are the cecropia trees, with their white stems
and large palmated leaves standing up like great candelabra. Sometimes
the ground is carpeted with large flowers, yellow, pink, or white, that
have fallen from some invisible tree-top above; or the air is filled
with a delicious perfume, the source of which one seeks around in vain,
for the flowers that cause it are far overhead out of sight, lost in the
great over-shadowing crown of verdure."
"But," he adds, "the uniformity of climate which has led to this rich
luxuriance and endless variety of vegetation is also the cause of a
monotony that in time becomes oppressive." To quote the words of Mr.
Belt: "Unknown are the autumn tints, the bright browns and yellows of
English woods; much less the crimsons, purples, and yellows of Canada,
where the dying foliage rivals, nay, excels, the expiring dolphin in
splendour. Unknown the cold sleep of winter; unknown the lovely
awakening of vegetation at the first gentle touch of spring. A ceaseless
round of ever-active life weaves the fairest scenery of the tropics into
one monotonous whole, of which the component parts exhibit in detail
untold variety of beauty."
Siberia is no doubt as a rule somewhat severe and inhospitable, but M.
Patrin mentions with enthusiasm how one day descending from the frozen
summits of the Altai, he came suddenly on a view of the plain of the
Obi--the most beautiful spectacle, he says, which he had ever witnessed.
Behind him were barren rocks and the snows of winter, in front a great
plain, not indeed entirely green, or green only in places, and for the
rest covered by three flowers, the purple Siberian Iris, the golden
Hemerocallis, and the silvery Narcissus--green, purple, gold, and white,
as far as the eye could reach.
Wallace tells us that he himself has derived the keenest enjoyment from
his sense of colour:--
"The heavenly blue of the firmament, the glowing tints of sunset, the
exquisite purity of the snowy mountains, and the endless shades of green
presented by the verdure-clad surface of the earth, are a never-failing
source of pleasure to all who enjoy the inestimable gift of sight. Yet
these constitute, as it were, but the frame and background of a
marvellous and ever-changing picture. In contrast with these broad and
soothing tints, we have presented to us in the vegetable and animal
worlds an infinite variety of objects adorned with the most beautiful
and most varied hues. Flowers, insects, and birds are the organisms
most generally ornamented in this way; and their symmetry of form, their
variety of structure, and the lavish abundance with which they clothe
and enliven the earth, cause them to be objects of universal admiration.
The relation of this wealth of colour to our mental and moral nature is
indisputable. The child and the savage alike admire the gay tints of
flowers, birds, and insects; while to many of us their contemplation
brings a solace and enjoyment which is both intellectually and morally
beneficial. It can then hardly excite surprise that this relation was
long thought to afford a sufficient explanation of the phenomena of
colour in nature; and although the fact that--
Full many a flower is born to blush unseen,
And waste its sweetness on the desert air,
might seem to throw some doubt on the sufficiency of the explanation,
the answer was easy,--that in the progress of discovery man would,
sooner or later, find out and enjoy every beauty that the hidden
recesses of the earth have in store for him."
Professor Colvin speaks with special admiration of Greek scenery:--
"In other climates, it is only in particular states of the weather that
the remote ever seems so close, and then with an effect which is sharp
and hard as well as clear; here the clearness is soft; nothing cuts or
glitters, seen through that magic distance; the air has not only a new
transparency so that you can see farther into it than elsewhere, but a
new quality, like some crystal of an unknown water, so that to see into
it is greater glory." Speaking of the ranges and promontories of sterile
limestone, the same writer observes that their colours are as austere
and delicate as the forms. "If here the scar of some old quarry throws a
stain, or there the clinging of some thin leafage spreads a bloom, the
stain is of precious gold, and the bloom of silver. Between the blue of
the sky and the tenfold blue of the sea these bare ranges seem, beneath
that daylight, to present a whole system of noble colour flung abroad
over perfect forms. And wherever, in the general sterility, you find a
little moderate verdure--a little moist grass, a cluster of
cypresses--or whenever your eye lights upon the one wood of the
district, the long olive grove of the Cephissus, you are struck with a
sudden sense of richness, and feel as if the splendours of the tropics
would be nothing to this."
Most travellers have been fascinated by the beauty of night in the
tropics. Our evenings no doubt are often delicious also, though the mild
climate we enjoy is partly due to the sky being so often overcast. In
parts of the tropics, however, the air is calm and cloudless throughout
nearly the whole of the year. There is no dew, and the inhabitants sleep
on the house-tops, in full view of the brightness of the stars and the
beauty of the sky, which is almost indescribable.
"Il faisait," says Bernardin de St. Pierre of such a scene, "une de ces
nuits délicieuses, si communes entre les tropiques, et dont le plus
abile pinceau ne rendrait pas le beauté. La lune paraissait au milieu du
firmament, entourée d'un rideau de nuages, que ses rayons dissipaient
par degrés. Sa lumière se répandait insensiblement sur les montagnes de
l'île et sur leurs pitons, qui brillaient d'un vert argenté. Les vents
retenaient leurs haleines. On entendait dans les bois, au fond des
vallées, au haut des rochers, de petits cris, de doux murmures
d'oiseaux, qui se caressaient dans leurs nids, réjouis par la clarté de
la nuit et la tranquillité de l'air. Tous, jusqu'aux insectes,
bruissaient sous l'herbe. Les étoiles étincelaient au ciel, et se
réfléchissaient au sein de la mer, qui répétait leurs images
tremblantes."
In the Arctic and Antarctic regions the nights are often made quite
gorgeous by the Northern Lights or Aurora borealis, and the
corresponding appearance in the Southern hemisphere. The Aurora borealis
generally begins towards evening, and first appears as a faint glimmer
in the north, like the approach of dawn. Gradually a curve of light
spreads like an immense arch of yellowish-white hue, which gains rapidly
in brilliancy, flashes and vibrates like a flame in the wind. Often two
or even three arches appear one over the other. After a while coloured
rays dart upwards in divergent pencils, often green below, yellow in the
centre, and crimson above, while it is said that sometimes almost
black, or at least very dark violet, rays are interspersed among the
rings of light, and heighten their effect by contrast. Sometimes the two
ends of the arch seem to rise off the horizon, and the whole sheet of
light throbs and undulates like a fringed curtain of light; sometimes
the sheaves of rays unite into an immense cupola; while at others the
separate rays seem alternately lit and extinguished. Gradually the light
flickers and fades away, and has generally disappeared before the first
glimpse of dawn.
We seldom see the Aurora in the south of England, but we must not
complain; our winters are mild, and every month has its own charm and
beauty.
In January we have the lengthening days.
" February " the first butterfly.
" March " the opening buds.
" April " the young leaves and spring flowers.
" May " the song of birds.
" June " the sweet new-mown hay.
" July " the summer flowers.
" August " the golden grain.
" September " the fruit.
" October " the autumn tints.
" November " the hoar frost on trees and the pure snow.
" December " last not least, the holidays of Christmas, and the
bright fireside.
It is well to begin the year in January, for we have then before us all
the hope of spring.
Oh wind,
If winter comes, can spring be long behind?[8]
Spring seems to revive us all. In the Song of Solomon--
My beloved spake, and said unto me,
Rise up, my love, my fair one, and come away.
For, lo, the winter is past,
The rain is over and gone;
The flowers appear on the earth;
The time of the singing of birds is come,
The voice of the turtle is heard in our land,
The fig tree putteth forth her green figs,
And the vines with the tender grape give a good smell.
"But indeed there are days," says Emerson, "which occur in this climate,
at almost any season of the year, wherein the world reaches its
perfection, when the air, the heavenly bodies, and the earth make a
harmony, as if nature would indulge her offspring.... These halcyon days
may be looked for with a little more assurance in that pure October
weather, which we distinguish by the name of the Indian summer. The day,
immeasurably long, sleeps over the broad hills and warm wide fields. To
have lived through all its sunny hours, seems longevity enough." Yet
does not the very name of Indian summer imply the superiority of the
summer itself,--the real, the true summer, "when the young corn is
bursting into ear; the awned heads of rye, wheat, and barley, and the
nodding panicles of oats, shoot from their green and glaucous stems, in
broad, level, and waving expanses of present beauty and future promise.
The very waters are strewn with flowers: the buck-bean, the
water-violet, the elegant flowering rush, and the queen of the waters,
the pure and splendid white lily, invest every stream and lonely mere
with grace."[9]
For our greater power of perceiving, and therefore of enjoying Nature,
we are greatly indebted to Science. Over and above what is visible to
the unaided eye, the two magic tubes, the telescope and microscope, have
revealed to us, at least partially, the infinitely great and the
infinitely little.
Science, our Fairy Godmother, will, unless we perversely reject her
help, and refuse her gifts, so richly endow us, that fewer hours of
labour will serve to supply us with the material necessaries of life,
leaving us more time to ourselves, more leisure to enjoy all that makes
life best worth living.
Even now we all have some leisure, and for it we cannot be too grateful.
"If any one," says Seneca, "gave you a few acres, you would say that you
had received a benefit; can you deny that the boundless extent of the
earth is a benefit? If a house were given you, bright with marble, its
roof beautifully painted with colours and gilding, you would call it no
small benefit. God has built for you a mansion that fears no fire or
ruin ... covered with a roof which glitters in one fashion by day, and
in another by night. Whence comes the breath which you draw; the light
by which you perform the actions of your life? the blood by which your
life is maintained? the meat by which your hunger is appeased?... The
true God has planted, not a few oxen, but all the herds on their
pastures throughout the world, and furnished food to all the flocks; he
has ordained the alternation of summer and winter ... he has invented so
many arts and varieties of voice, so many notes to make music.... We
have implanted in us the seeds of all ages, of all arts; and God our
Master brings forth our intellects from obscurity."[10]
FOOTNOTES:
[1] _Choses Vues._
[2] Wordsworth.
[3] Cicero, _De Natura Deorum_.
[4] Thoreau.
[5] Spenser.
[6] Darwin's _Voyage of the Beagle_.
[7] Hamerton's _Landscape_.
[8] Shelley.
[9] Howitt's _Book of the Seasons_.
[10] Seneca, _De Beneficiis_.
CHAPTER II
ON ANIMAL LIFE
If thy heart be right, then will every creature be to thee a
mirror of life, and a book of holy doctrine.
THOMAS À KEMPIS.
CHAPTER II
ON ANIMAL LIFE
There is no species of animal or plant which would not well repay, I
will not say merely the study of a day, but even the devotion of a
lifetime. Their form and structure, development and habits, geographical
distribution, relation to other living beings, and past history,
constitute an inexhaustible study.
When we consider how much we owe to the Dog, Man's faithful friend, to
the noble Horse, the patient Ox, the Cow, the Sheep, and our other
domestic animals, we cannot be too grateful to them; and if we cannot,
like some ancient nations, actually worship them, we have perhaps fallen
into the other extreme, underrate the sacredness of animal life, and
treat them too much like mere machines.
Some species, however, are no doubt more interesting than others,
especially perhaps those which live together in true communities, and
which offer so many traits--some sad, some comical, and all
interesting,--which reproduce more or less closely the circumstances of
our own life.
The modes of animal life are almost infinitely diversified; some live on
land, some in water; of those which are aquatic some dwell in rivers,
some in lakes or pools, some on the sea-shore, others in the depths of
the ocean. Some burrow in the ground, some find their home in the air.
Some live in the Arctic regions, some in the burning deserts; one little
beetle (Hydrobius) in the thermal waters of Hammam-Meskoutin, at a
temperature of 130°. As to food, some are carnivorous and wage open war;
some, more insidious, attack their victims from within; others feed on
vegetable food, on leaves or wood, on seeds or fruits; in fact, there is
scarcely an animal or vegetable substance which is not the special and
favourite food of one or more species. Hence to adapt them to these
various requirements we find the utmost differences of form and size
and structure. Even the same individual often goes through great
changes.
GROWTH AND METAMORPHOSES
The development, indeed, of an animal from birth to maturity is no mere
question of growth. The metamorphoses of Insects have long excited the
wonder and admiration of all lovers of nature. They depend to a great
extent on the fact that the little creatures quit the egg at an early
stage of development, and lead a different life, so that the external
forces acting on them, are very different from those by which they are
affected when they arrive at maturity. A remarkable case is that of
certain Beetles which are parasitic on Solitary Bees. The young larva is
very active, with six strong legs. It conceals itself in some flower,
and when the Bee comes in search of honey, leaps upon her, but is so
minute as not to be perceived. The Bee constructs her cell, stores it
with honey, and lays her egg. At that moment the little larva quits the
Bee and jumps on to the egg, which she proceeds gradually to devour.
Having finished the egg, she attacks the honey; but under these
circumstances the activity which was at first so necessary has become
useless; the legs which did such good service are no longer required;
and the active slim larva changes into a white fleshy grub, which floats
comfortably in the honey with its mouth just below the surface.
Even in the same group we may find great differences. For instance, in
the family of Insects to which Bees and Wasps belong, some have grub
larvæ, such as the Bee and Ant; some have larvæ like caterpillars, such
as the Sawflies; and there is a group of minute forms the larvæ of which
live inside the eggs of other insects, and present very remarkable and
abnormal forms.
These differences depend mainly on the mode of life and the character of
the food.
RUDIMENTARY ORGANS
Such modifications may be called adaptive, but there are others of a
different origin that have reference to the changes which the race has
passed through in bygone ages. In fact the great majority of animals do
go through metamorphoses (many of them as remarkable, though not so
familiar as those of insects), but in many cases they are passed through
within the egg and thus escape popular observation. Naturalists who
accept the theory of evolution, consider that the development of each
individual represents to a certain extent that which the species has
itself gone through in the lapse of ages; that every individual contains
within itself, so to say, a history of the race. Thus the rudimentary
teeth of Cows, Sheep, Whales, etc. (which never emerge from their
sockets), the rudimentary toes of many mammals, the hind legs of Whales
and of the Boa-constrictor, which are imbedded in the flesh, the
rudimentary collar-bone of the Dog, etc., are indications of descent
from ancestors in which these organs were fully developed. Again, though
used for such different purposes, the paddle of a Whale, the leg of a
Horse and of a Mole, the wing of a Bird or a Bat, and the arm of a Man,
are all constructed on the same model, include corresponding bones, and
are similarly arranged. The long neck of the Giraffe, and the short one
of the Whale (if neck it can be called), contain the same number of
vertebræ.
Even after birth the young of allied species resemble one another much
more than the mature forms. The stripes on the young Lion, the spots on
the young Blackbird, are well-known cases; and we find the same law
prevalent among the lower animals, as, for instance, among Insects and
Crustacea. The Lobster, Crab, Shrimp, and Barnacle are very unlike when
full grown, but in their young stages go through essentially similar
metamorphoses.
No animal is perhaps in this respect more interesting than the Horse.
The skull of a Horse and that of a Man, though differing so much, are,
says Flower,[11] "composed of exactly the same number of bones, having
the same general arrangement and relation to each other. Not only the
individual bones, but every ridge and surface for the attachment of
muscles, and every hole for the passage of artery or nerve, seen in the
one can be traced in the other." It is often said that the Horse
presents a remarkable peculiarity in that the canine teeth grow but
once. There are, however, in most Horses certain spicules or minute
points which are shed before the appearance of the permanent canines,
and which are probably the last remnants of the true milk canines.
The foot is reduced to a single toe, representing the third digit, but
the second and fourth, though rudimentary, are represented by the splint
bones; while the foot also contains traces of several muscles,
originally belonging to the toes which have now disappeared, and which
"linger as it were behind, with new relations and uses, sometimes in a
reduced, and almost, if not quite, functionless condition." Even Man
himself presents traces of gill-openings, and indications of other
organs which are fully developed in lower animals.
MODIFICATIONS
There is in New Zealand a form of Crow (Hura), in which the female has
undergone a very curious modification. It is the only case I know, in
which the bill is differently shaped in the two sexes. The bird has
taken on the habits of a Woodpecker, and the stout crow-like bill of the
cock-bird is admirably adapted to tap trees, and if they sound hollow,
to dig down to the burrow of the Insect; but it lacks the horny-pointed
tip of the tongue, which in the true Woodpecker is provided with
recurved hairs, thus enabling that bird to pierce the grub and draw it
out. In the Hura, however, the bill of the hen-bird has become much
elongated and slightly curved, and when the cock has dug down to the
burrow, the hen inserts her long bill and draws out the grub, which
they then divide between them: a very pretty illustration of the wife as
helpmate to the husband.
It was indeed until lately the general opinion that animals and plants
came into existence just as we now see them. We took pleasure in their
beauty; their adaptation to their habits and mode of life in many cases
could not be overlooked or misunderstood. Nevertheless the book of
Nature was like some missal richly illuminated, but written in an
unknown tongue. The graceful forms of the letters, the beauty of the
colouring, excited our wonder and admiration; but of the true meaning
little was known to us; indeed we scarcely realised that there was any
meaning to decipher. Now glimpses of the truth are gradually revealing
themselves, we perceive that there is a reason, and in many cases we
know what the reason is, for every difference in form, in size, and in
colour; for every bone and every feather, almost for every hair.[12]
COLOUR
The colours of animals, generally, I believe, serve as a protection. In
some, however, they probably render them more attractive to their mates,
of which the Peacock is one of the most remarkable illustrations.
In richness of colour birds and insects vie even with flowers. "One fine
red admiral butterfly," says Jefferies,[13] "whose broad wings,
stretched out like fans, looked simply splendid floating round and round
the willows which marked the margin of a dry pool. His blue markings
were really blue--blue velvet--his red and the white stroke shone as if
sunbeams were in his wings. I wish there were more of these butterflies;
in summer, dry summer, when the flowers seem gone and the grass is not
so dear to us, and the leaves are dull with heat, a little colour is so
pleasant. To me colour is a sort of food; every spot of colour is a drop
of wine to the spirit."
The varied colours which add so much to the beauty of animals and
plants are not only thus a delight to the eye, but afford us also some
of the most interesting problems in Natural History. Some probably are
not in themselves of any direct advantage. The brilliant mother-of-pearl
of certain shells, which during life is completely hidden, the rich
colours of some internal organs of animals, are not perhaps of any
direct benefit, but are incidental, like the rich and brilliant hues of
many minerals and precious stones.
But although this may be true, I believe that most of these colours are
now of some advantage. "The black back and silvery belly of fishes" have
been recently referred to by a distinguished naturalist as being
obviously of no direct benefit. I should on the contrary have quoted
this case as one where the advantage was obvious. The dark back renders
the fish less conspicuous to an eye looking down into the water; while
the white under-surface makes them less visible from below. The animals
of the desert are sand-coloured; those of the Arctic regions are white
like snow, especially in winter; and pelagic animals are blue.
Let us take certain special cases. The Lion, like other desert animals,
is sand-coloured; the Tiger which lives in the Jungle has vertical
stripes, making him difficult to see among the upright grass; Leopards
and the tree-cats are spotted, like rays of light seen through leaves.
An interesting case is that of the animals living in the Sargasso or
gulf-weed of the Atlantic. These creatures--Fish, Crustacea, and
Mollusks alike--are characterised by a peculiar colouring, not
continuously olive like the Seaweed itself, but blotched with rounded
more or less irregular patches of bright, opaque white, so as closely to
resemble fronds covered with patches of Flustra or Barnacles.
Take the case of caterpillars, which are especially defenceless, and
which as a rule feed on leaves. The smallest and youngest are green,
like the leaves on which they live. When they become larger, they are
characterised by longitudinal lines, which break up the surface and thus
render them less conspicuous. On older and larger ones the lines are
diagonal, like the nerves of leaves. Conspicuous caterpillars are
generally either nauseous in taste, or protected by hairs.
[Illustration: Fig. 1.--_Choerocampa porcellus._]
I say "generally," because there are some interesting exceptions. The
large caterpillars of some of the Elephant Hawkmoths are very
conspicuous, and rendered all the more so by the presence of a pair of
large eyelike spots. Every one who sees one of these caterpillars is
struck by its likeness to a snake, and the so-called "eyes" do much to
increase the deception. Moreover, the ring on which they are placed is
swollen, and the insect, when in danger, has the habit of retracting its
head and front segments, which gives it an additional resemblance to
some small reptile. That small birds are, as a matter of fact, afraid of
these caterpillars (which, however, I need not say, are in reality
altogether harmless) Weismann has proved by actual experiment. He put
one of these caterpillars in a tray, in which he was accustomed to place
seed for birds. Soon a little flock of sparrows and other small birds
assembled to feed as usual. One of them lit on the edge of this tray,
and was just going to hop in, when she spied the caterpillar.
Immediately she began bobbing her head up and down in the odd way which
some small birds have, but was afraid to go nearer. Another joined her
and then another, until at last there was a little company of ten or
twelve birds all looking on in astonishment, but not one ventured into
the tray; while one bird, which lit in it unsuspectingly, beat a hasty
retreat in evident alarm as soon as she perceived the caterpillar. After
waiting for some time, Weismann removed it, when the birds soon attacked
the seeds. Other caterpillars also are probably protected by their
curious resemblance to spotted snakes. One of the large Indian
caterpillars has even acquired the power of hissing.
Among perfect insects many resemble closely the substances near which
they live. Some moths are mottled so as to mimic the bark of trees, or
moss, or the surface of stones. One beautiful tropical butterfly has a
dark wing on which are painted a series of green leaf tips, so that it
closely resembles the edge of a pinnate leaf projecting out of shade
into sunshine.
The argument is strengthened by those cases in which the protection, or
other advantage, is due not merely to colour, but partly also to form.
Such are the insects which resemble sticks or leaves. Again, there are
cases in which insects mimic others, which, for some reason or other,
are less liable to danger. So also many harmless animals mimic others
which are poisonous or otherwise well protected. Some butterflies, as
Mr. Bates has pointed out, mimic others which are nauseous in taste, and
therefore not attacked by birds. In these cases it is generally only the
females that are mimetic, and in some cases only a part of them, so that
there are two, or even three, kinds of females, the one retaining the
normal colouring of the group, the other mimicking another species. Some
spiders closely resemble Ants, and several other insects mimic Wasps or
Hornets.
Some reptiles and fish have actually the power of changing the colour of
their skin so as to adapt themselves to their surroundings.
Many cases in which the colouring does not at first sight appear to be
protective, will on consideration be found to be so. It has, for
instance, been objected that sheep are not coloured green; but every
mountaineer knows that sheep could not have had a colour more adapted to
render them inconspicuous, and that it is almost impossible to
distinguish them from the rocks which so constantly crop up on hill
sides. Even the brilliant blue of the Kingfisher, which in a museum
renders it so conspicuous, in its native haunts, on the contrary, makes
it difficult to distinguish from a flash of light upon the water; and
the richly-coloured Woodpecker wears the genuine dress of a
Forester--the green coat and crimson cap.
It has been found that some brilliantly coloured and conspicuous animals
are either nauseous or poisonous. In these cases the brilliant colour
is doubtless a protection by rendering them more unmistakable.
COMMUNITIES
Some animals may delight us especially by their beauty, such as birds or
butterflies; others may surprise us by their size, as Elephants and
Whales, or the still more marvellous monsters of ancient times; may
fascinate us by their exquisite forms, such as many microscopic shells;
or compel our reluctant attention by their similarity to us in
structure; but none offer more points of interest than those which live
in communities. I do not allude to the temporary assemblages of
Starlings, Swallows, and other birds at certain times of year, nor even
to the permanent associations of animals brought together by common
wants in suitable localities, but to regular and more or less organised
associations. Such colonies as those of Rooks and Beavers have no doubt
interesting revelations and surprises in store for us, but they have not
been as yet so much studied as those of some insects. Among these the
Hive Bees, from the beauty and regularity of their cells, from their
utility to man, and from the debt we owe them for their unconscious
agency in the improvement of flowers, hold a very high place; but they
are probably less intelligent, and their relations with other animals
and with one another are less complex than in the case of Ants, which
have been so well studied by Gould, Huber, Forel, M'Cook, and other
naturalists.
The subject is a wide one, for there are at least a thousand species of
Ants, no two of which have the same habits. In this country we have
rather more than thirty, most of which I have kept in confinement. Their
life is comparatively long: I have had working Ants which were seven
years old, and a Queen Ant lived in one of my nests for fifteen years.
The community consists, in addition to the young, of males, which do no
work, of wingless workers, and one or more Queen mothers, who have at
first wings, which, however, after one Marriage flight, they throw off,
as they never leave the nest again, and in it wings would of course be
useless. The workers do not, except occasionally, lay eggs, but carry on
all the affairs of the community. Some of them, and especially the
younger ones, remain in the nest, excavate chambers and tunnels, and
tend the young, which are sorted up according to age, so that my nests
often had the appearance of a school, with the children arranged in
classes.
In our English Ants the workers in each species are all similar except
in size, but among foreign species there are some in which there are two
or even more classes of workers, differing greatly not only in size, but
also in form. The differences are not the result of age, nor of race,
but are adaptations to different functions, the nature of which,
however, is not yet well understood. Among the Termites those of one
class certainly seem to act as soldiers, and among the true Ants also
some have comparatively immense heads and powerful jaws. It is doubtful,
however, whether they form a real army. Bates observed that on a
foraging expedition the large-headed individuals did not walk in the
regular ranks, nor on the return did they carry any of the booty, but
marched along at the side, and at tolerably regular intervals, "like
subaltern officers in a marching regiment." He is disposed, however, to
ascribe to them a much humbler function, namely, to serve merely "as
indigestible morsels to the ant thrushes." This, I confess, seems to me
improbable.
Solomon was, so far as we yet know, quite correct in describing Ants as
having "neither guide, overseer, nor ruler." The so-called Queens are
really Mothers. Nevertheless it is true, and it is curious, that the
working Ants and Bees always turn their heads towards the Queen. It
seems as if the sight of her gave them pleasure. On one occasion, while
moving some Ants from one nest into another for exhibition at the Royal
Institution, I unfortunately crushed the Queen and killed her. The
others, however, did not desert her, or draw her out as they do dead
workers, but on the contrary carried her into the new nest, and
subsequently into a larger one with which I supplied them, congregating
round her for weeks just as if she had been alive. One could hardly
help fancying that they were mourning her loss, or hoping anxiously for
her recovery.
The Communities of Ants are sometimes very large, numbering even up to
500,000 individuals; and it is a lesson to us, that no one has ever yet
seen a quarrel between any two Ants belonging to the same community. On
the other hand it must be admitted that they are in hostility, not only
with most other insects, including Ants of different species, but even
with those of the same species if belonging to different communities. I
have over and over again introduced Ants from one of my nests into
another nest of the same species, and they were invariably attacked,
seized by a leg or an antenna, and dragged out.
It is evident therefore that the Ants of each community all recognise
one another, which is very remarkable. But more than this, I several
times divided a nest into two halves, and found that even after a
separation of a year and nine months they recognised one another, and
were perfectly friendly; while they at once attacked Ants from a
different nest, although of the same species.
It has been suggested that the Ants of each nest have some sign or
password by which they recognise one another. To test this I made some
insensible. First I tried chloroform, but this was fatal to them; and as
therefore they were practically dead, I did not consider the test
satisfactory. I decided therefore to intoxicate them. This was less easy
than I had expected. None of my Ants would voluntarily degrade
themselves by getting drunk. However, I got over the difficulty by
putting them into whisky for a few moments. I took fifty specimens,
twenty-five from one nest and twenty-five from another, made them dead
drunk, marked each with a spot of paint, and put them on a table close
to where other Ants from one of the nests were feeding. The table was
surrounded as usual with a moat of water to prevent them from straying.
The Ants which were feeding soon noticed those which I had made drunk.
They seemed quite astonished to find their comrades in such a
disgraceful condition, and as much at a loss to know what to do with
their drunkards as we are. After a while, however, to cut my story
short, they carried them all away: the strangers they took to the edge
of the moat and dropped into the water, while they bore their friends
home into the nest, where by degrees they slept off the effects of the
spirit. Thus it is evident that they know their friends even when
incapable of giving any sign or password.
This little experiment also shows that they help comrades in distress.
If a Wolf or a Rook be ill or injured, we are told that it is driven
away or even killed by its comrades. Not so with Ants. For instance, in
one of my nests an unfortunate Ant, in emerging from the chrysalis skin,
injured her legs so much that she lay on her back quite helpless. For
three months, however, she was carefully fed and tended by the other
Ants. In another case an Ant in the same manner had injured her antennæ.
I watched her also carefully to see what would happen. For some days she
did not leave the nest. At last one day she ventured outside, and after
a while met a stranger Ant of the same species, but belonging to another
nest, by whom she was at once attacked. I tried to separate them, but
whether by her enemy, or perhaps by my well-meant but clumsy kindness,
she was evidently much hurt and lay helplessly on her side. Several
other Ants passed her without taking any notice, but soon one came up,
examined her carefully with her antennæ, and carried her off tenderly to
the nest. No one, I think, who saw it could have denied to that Ant one
attribute of humanity, the quality of kindness.
The existence of such communities as those of Ants or Bees implies, no
doubt, some power of communication, but the amount is still a matter of
doubt. It is well known that if one Bee or Ant discovers a store of
food, others soon find their way to it. This, however, does not prove
much. It makes all the difference whether they are brought or sent. If
they merely accompany on her return a companion who has brought a store
of food, it does not imply much. To test this, therefore, I made
several experiments. For instance, one cold day my Ants were almost all
in their nests. One only was out hunting and about six feet from home. I
took a dead bluebottle fly, pinned it on to a piece of cork, and put it
down just in front of her. She at once tried to carry off the fly, but
to her surprise found it immovable. She tugged and tugged, first one way
and then another for about twenty minutes, and then went straight off to
the nest. During that time not a single Ant had come out; in fact she
was the only Ant of that nest out at the time. She went straight in, but
in a few seconds--less than half a minute,--came out again with no less
than twelve friends, who trooped off with her, and eventually tore up
the dead fly, carrying it off in triumph.
Now the first Ant took nothing home with her; she must therefore somehow
have made her friends understand that she had found some food, and
wanted them to come and help her to secure it. In all such cases,
however, so far as my experience goes, the Ants brought their friends,
and some of my experiments indicated that they are unable to send them.
Certain species of Ants, again, make slaves of others, as Huber first
observed. If a colony of the slave-making Ants is changing the nest, a
matter which is left to the discretion of the slaves, the latter carry
their mistresses to their new home. Again, if I uncovered one of my
nests of the Fuscous Ant (Formica fusca), they all began running about
in search of some place of refuge. If now I covered over one small part
of the nest, after a while some Ant discovered it. In such a case,
however, the brave little insect never remained there, she came out in
search of her friends, and the first one she met she took up in her
jaws, threw over her shoulder (their way of carrying friends), and took
into the covered part; then both came out again, found two more friends
and brought them in, the same manoeuvre being repeated until the whole
community was in a place of safety. This I think says much for their
public spirit, but seems to prove that, in F. fusca at least, the powers
of communication are but limited.
One kind of slave-making Ant has become so completely dependent on their
slaves, that even if provided with food they will die of hunger, unless
there is a slave to put it into their mouth. I found, however, that they
would thrive very well if supplied with a slave for an hour or so once a
week to clean and feed them.
But in many cases the community does not consist of Ants only. They have
domestic animals, and indeed it is not going too far to say that they
have domesticated more animals than we have. Of these the most important
are Aphides. Some species keep Aphides on trees and bushes, others
collect root-feeding Aphides into their nests. They serve as cows to the
Ants, which feed on the honey-dew secreted by the Aphides. Not only,
moreover, do the Ants protect the Aphides themselves, but collect their
eggs in autumn, and tend them carefully through the winter, ready for
the next spring. Many other insects are also domesticated by Ants, and
some of them, from living constantly underground, have completely lost
their eyes and become quite blind.
But I must not let myself be carried away by this fascinating subject,
which I have treated more at length in another work.[14] I will only say
that though their intelligence is no doubt limited, still I do not think
that any one who has studied the life-history of Ants can draw any
fundamental line of separation between instinct and reason.
When we see a community of Ants working together in perfect harmony, it
is impossible not to ask ourselves how far they are mere exquisite
automatons; how far they are conscious beings? When we watch an ant-hill
tenanted by thousands of industrious inhabitants, excavating chambers,
forming tunnels, making roads, guarding their home, gathering food,
feeding the young, tending their domestic animals--each one fulfilling
its duties industriously, and without confusion,--it is difficult
altogether to deny to them the gift of reason; and all our recent
observations tend to confirm the opinion that their mental powers differ
from those of men, not so much in kind as in degree.
FOOTNOTES:
[11] _The Horse._
[12] Lubbock, _Fifty Years of Science_.
[13] _The Open Air._
[14] _Ants, Bees, and Wasps._
CHAPTER III
ON ANIMAL LIFE--_continued_
An organic being is a microcosm--a little universe, formed of a
host of self-propagating organisms, inconceivably minute and
numerous as the stars of heaven.
DARWIN.
CHAPTER III
ON ANIMAL LIFE--_continued._
We constantly speak of animals as free. A fish, says Ruskin, "is much
freer than a Man; and as to a fly, it is a black incarnation of
freedom." It is pleasant to think of anything as free, but in this case
the idea is, I fear, to a great extent erroneous. Young animals may
frolic and play, but older ones take life very seriously. About the
habits of fish and flies, indeed, as yet we know very little. Any one,
however, who will watch animals will soon satisfy himself how diligently
they work. Even when they seem to be idling over flowers, or wandering
aimlessly about, they are in truth diligently seeking for food, or
collecting materials for nests. The industry of Bees is proverbial. When
collecting honey or pollen they often visit over twenty flowers in a
minute, keeping constantly to one species, without yielding a moment's
dalliance to any more sweet or lovely tempter. Ants fully deserve the
commendation of Solomon. Wasps have not the same reputation for
industry; but I have watched them from before four in the morning till
dark at night working like animated machines without a moment's rest or
intermission. Sundays and Bank Holidays are all the same to them. Again,
Birds have their own gardens and farms from which they do not wander,
and within which they will tolerate no interference. Their ideas of the
rights of property are far stricter than those of some statesmen. As to
freedom, they have their daily duties as much as a mechanic in a mill or
a clerk in an office. They suffer under alarms, moreover, from which we
are happily free. Mr. Galton believes that the life of wild animals is
very anxious. "From my own recollection," he says, "I believe that every
antelope in South Africa has to run for its life every one or two days
upon an average, and that he starts or gallops under the influence of a
false alarm many times in a day. Those who have crouched at night by the
side of pools in the desert, in order to have a shot at the beasts that
frequent it, see strange scenes of animal life; how the creatures gambol
at one moment and fight at another; how a herd suddenly halts in
strained attention, and then breaks into a maddened rush as one of them
becomes conscious of the stealthy movements or rank scent of a beast of
prey. Now this hourly life-and-death excitement is a keen delight to
most wild creatures, but must be peculiarly distracting to the
comfort-loving temperament of others. The latter are alone suited to
endure the crass habits and dull routine of domesticated life. Suppose
that an animal which has been captured and half-tamed, received
ill-usage from his captors, either as punishment or through mere
brutality, and that he rushed indignantly into the forest with his ribs
aching from blows and stones. If a comfort-loving animal, he will
probably be no gainer by the change, more serious alarms and no less
ill-usage awaits him: he hears the roar of the wild beasts, and the
headlong gallop of the frightened herds, and he finds the buttings and
the kicks of other animals harder to endure than the blows from which he
fled: he has peculiar disadvantages from being a stranger; the herds of
his own species which he seeks for companionship constitute so many
cliques, into which he can only find admission by more fighting with
their strongest members than he has spirit to undergo. As a set-off
against these miseries, the freedom of savage life has no charms for his
temperament; so the end of it is, that with a heavy heart he turns back
to the habitation he had quitted."
But though animals may not be free, I hope and believe that they are
happy. Dr. Hudson, an admirable observer, assures us with confidence
that the struggle for existence leaves them much leisure and famous
spirits. "In the animal world," he exclaims,[15] "what happiness reigns!
What ease, grace, beauty, leisure, and content! Watch these living
specks as they glide through their forests of algæ, all 'without hurry
and care,' as if their 'span-long lives' really could endure for the
thousand years that the old catch pines for. Here is no greedy jostling
at the banquet that nature has spread for them; no dread of each other;
but a leisurely inspection of the field, that shows neither the pressure
of hunger nor the dread of an enemy.
"'To labour and to be content' (that 'sweet life' of the son of
Sirach)--to be equally ready for an enemy or a friend--to trust in
themselves alone, to show a brave unconcern for the morrow, all these
are the admirable points of a character almost universal among animals,
and one that would lighten many a heart were it more common among men.
That character is the direct result of the golden law 'If one will not
work, neither let him eat'; a law whose stern kindness, unflinchingly
applied, has produced whole nations of living creatures, without a
pauper in their ranks, flushed with health, alert, resolute,
self-reliant, and singularly happy."
It has often been said that Man is the only animal gifted with the
power of enjoying a joke, but if animals do not laugh, at any rate they
sometimes play. We are, indeed, apt perhaps to credit them with too much
of our own attributes and emotions, but we can hardly be mistaken in
supposing that they enjoy certain scents and sounds. It is difficult to
separate the games of kittens and lambs from those of children. Our
countryman Gould long ago described the "amusements or sportive
exercises" which he had observed among Ants. Forel was at first
incredulous, but finally confirmed these statements; and, speaking of
certain tropical Ants, Bates says "the conclusion that they were engaged
in play was irresistible."
SLEEP
We share with other animals the great blessing of Sleep, nature's soft
nurse, "the mantle that covers thought, the food that appeases hunger,
the drink that quenches thirst, the fire that warms cold, the cold that
moderates heat, the coin that purchases all things, the balance and
weight that equals the shepherd with the king, and the simple with the
wise." Some animals dream as we do; Dogs, for instance, evidently dream
of the chase. With the lower animals which cannot shut their eyes it is,
however, more difficult to make sure whether they are awake or asleep. I
have often noticed insects at night, even when it was warm and light,
behave just as if they were asleep, and take no notice of objects which
would certainly have startled them in the day. The same thing has also
been observed in the case of fish.
But why should we sleep? What a remarkable thing it is that one-third of
our life should be passed in unconsciousness. "Half of our days," says
Sir T. Browne, "we pass in the shadow of the earth, and the brother of
death extracteth a third part of our lives." The obvious suggestion is
that we require rest. But this does not fully meet the case. In sleep
the mind is still awake, and lives a life of its own: our thoughts
wander, uncontrolled, by the will. The mind, therefore, is not
necessarily itself at rest; and yet we all know how it is refreshed by
sleep.
But though animals sleep, many of them are nocturnal in their habits.
Humboldt gives a vivid description of night in a Brazilian forest.
"Everything passed tranquilly till eleven at night, and then a noise so
terrible arose in the neighbouring forest that it was almost impossible
to close our eyes. Amid the cries of so many wild beasts howling at once
the Indians discriminated such only as were (at intervals) heard
separately. These were the little soft cries of the sapajous, the moans
of the alouate apes, the howlings of the jaguar and couguar, the peccary
and the sloth, and the cries of (many) birds. When the jaguars
approached the skirt of the forest our dog, which till then had never
ceased barking, began to howl and seek for shelter beneath our hammocks.
Sometimes, after a long silence, the cry of the tiger came from the tops
of the trees; and then it was followed by the sharp and long whistling
of the monkeys, which appeared to flee from the danger which threatened
them. We heard the same noises repeated during the course of whole
months whenever the forest approached the bed of the river.
"When the natives are interrogated on the causes of the tremendous noise
made by the beasts of the forest at certain hours of the night, the
answer is, they are keeping the feast of the full moon. I believe this
agitation is most frequently the effect of some conflict that has arisen
in the depths of the forest. The jaguars, for instance, pursue the
peccaries and the tapirs, which, having no defence, flee in close
troops, and break down the bushes they find in their way. Terrified at
this struggle, the timid and distrustful monkeys answer, from the tops
of the trees, the cries of the large animals. They awaken the birds that
live in society, and by degrees the whole assembly is in commotion. It
is not always in a fine moonlight, but more particularly at the time of
a storm of violent showers, that this tumult takes place among the wild
beasts. 'May heaven grant them a quiet night and repose, and us also!'
said the monk who accompanied us to the Rio Negro, when, sinking with
fatigue, he assisted in arranging our accommodation for the night."
Life is indeed among animals a struggle for existence, and in addition
to the more usual weapons--teeth and claws--we find in some animals
special and peculiar means of offence and defence.
If we had not been so familiarised with the fact, the possession of
poison might well seem a wonderful gift. That a fluid, harmless in one
animal itself, should yet prove so deadly when transferred to others, is
certainly very remarkable; and though the venom of the Cobra or the
Rattlesnake appeal perhaps more effectively to our imagination, we have
conclusive evidence of concentrated poison even in the bite of a midge,
which may remain for days perceptible. The sting of a Bee or Wasp,
though somewhat similar in its effect, is a totally different organ,
being a modified ovipositor. Some species of Ants do not sting in the
ordinary sense, but eject their acrid poison to a distance of several
inches.
Another very remarkable weapon is the electric battery of certain Eels,
of the Electric Cat Fish, and the Torpedoes, one of which is said to be
able to discharge an amount of electricity sufficient to kill a Man.
Some of the Medusæ and other Zoophytes are armed by millions of minute
organs known as "thread cells." Each consists of a cell, within which a
firm, elastic thread is tightly coiled. The moment the Medusa touches
its prey the cells burst and the threads spring out. Entering the flesh
as they do by myriads, they prove very effective weapons.
The ink of the Sepia has passed into a proverb. The animal possesses a
store of dark fluid, which, if attacked, it at once ejects, and thus
escapes under cover of the cloud thus created.
The so-called Bombardier Beetles, when attacked, discharge at the enemy,
from the hinder part of their body, an acrid fluid which, as soon as it
comes in contact with air, explodes with a sound resembling a miniature
gun. Westwood mentions, on the authority of Burchell, that on one
occasion, "whilst resting for the night on the banks of one of the
large South American rivers, he went out with a lantern to make an
astronomical observation, accompanied by one of his black servant boys;
and as they were proceeding, their attention was directed to numerous
beetles running about upon the shore, which, when captured, proved to be
specimens of a large species of Brachinus. On being seized they
immediately began to play off their artillery, burning and staining the
flesh to such a degree that only a few specimens could be captured with
the naked hand, and leaving a mark which remained a considerable time.
Upon observing the whitish vapour with which the explosions were
accompanied, the negro exclaimed in his broken English, with evident
surprise, 'Ah, massa, they make smoke!'"
Many other remarkable illustrations might be quoted; as for instance the
web of the Spider, the pit of the Ant Lion, the mephitic odour of the
Skunk.
SENSES
We generally attribute to animals five senses more or less resembling
our own. But even as regards our own senses we really know or
understand very little. Take the question of colour. The rainbow is
commonly said to consist of seven colours--red, orange, yellow, green,
blue, indigo, and violet.
But it is now known that all our colour sensations are mixtures of three
simple colours, red, green, and violet. We are, however, absolutely
ignorant how we perceive these colours. Thomas Young suggested that we
have three different systems of nerve fibres, and Helmholtz regards this
as "a not improbable supposition"; but so far as microscopical
examination is concerned, there is no evidence whatever for it.
Or take again the sense of Hearing. The vibrations of the air no doubt
play upon the drum of the ear, and the waves thus produced are conducted
through a complex chain of small bones to the fenestra ovalis and so to
the inner ear or labyrinth. But beyond this all is uncertainty. The
labyrinth consists mainly of two parts (1) the cochlea, and (2) the
semicircular canals, which are three in number, standing at right angles
to one another. It has been supposed that they enable us to maintain
the equilibrium of the body, but no satisfactory explanation of their
function has yet been given. In the cochlea, Corti discovered a
remarkable organ consisting of some four thousand complex arches, which
increase regularly in length and diminish in height. They are connected
at one end with the fibres of the auditory nerve, and Helmholtz has
suggested that the waves of sound play on them, like the fingers of a
performer on the keys of a piano, each separate arch corresponding to a
different sound. We thus obtain a glimpse, though but a glimpse, of the
manner in which perhaps we hear; but when we pass on to the senses of
smell and taste, all we know is that the extreme nerve fibres terminate
in certain cells which differ in form from those of the general surface;
but in what manner the innumerable differences of taste or smell are
communicated to the brain, we are absolutely ignorant.
If then we know so little about ourselves, no wonder that with reference
to other animals our ignorance is extreme.
We are too apt to suppose that the senses of animals must closely
resemble, and be confined to ours.
No one can doubt that the sensations of other animals differ in many
ways from ours. Their organs are sometimes constructed on different
principles, and situated in very unexpected places. There are animals
which have eyes on their backs, ears in their legs, and sing through
their sides.
We all know that the senses of animals are in many cases much more acute
than ours, as for instance the power of scent in the dog, of sight in
the eagle. Moreover, our eye is much more sensitive to some colours than
to others; least so to crimson, then successively to red, orange,
yellow, blue, and green; the sensitiveness for green being as much as
750 times as great as for red. This alone may make objects appear of
very different colours to different animals.
Nor is the difference one of degree merely. The rainbow, as we see it,
consists of seven colours--red, orange, yellow, green, blue, indigo, and
violet. But though the red and violet are the limits of the visible
spectrum, they are not the limits of the spectrum itself, there are
rays, though invisible to us, beyond the red at the one end, and beyond
the violet at the other: the existence of the ultra red can be
demonstrated by the thermometer; while the ultra violet are capable of
taking a photograph. But though the red and violet are respectively the
limits of our vision, I have shown[16] by experiments which have been
repeated and confirmed by other naturalists, that some of the lower
animals are capable of perceiving the ultra-violet rays, which to us are
invisible. It is an interesting question whether these rays may not
produce on them the impression of a new colour, or colours, differing
from any of those known to us.
So again with hearing, not only may animals in some cases hear better
than we do, but sounds which are beyond the reach of our ears, may be
audible to theirs. Even among ourselves the power of hearing shrill
sounds is greater in some persons than in others. Sound, as we know, is
produced by vibration of the air striking on the drum of the ear, and
the fewer are the vibrations in a second, the deeper is the sound, which
becomes shriller and shriller as the waves of sound become more rapid.
In human ears the limits of hearing are reached when about 35,000
vibrations strike the drum of the ear in a second.
Whatever the explanation of the gift of hearing in ourselves may be,
different plans seem to be adopted in the case of other animals. In many
Crustacea and Insects there are flattened hairs each connected with a
nerve fibre, and so constituted as to vibrate in response to particular
notes. In others the ear cavity contains certain minute solid bodies,
known as otoliths, which in the same way play upon the nerve fibres.
Sometimes these are secreted by the walls of the cavity itself, but
certain Crustacea have acquired the remarkable habit of selecting after
each moult suitable particles of sand, which they pick up with their
pincers and insert into their ears.
Many insects, besides the two large "compound" eyes one on each side of
the head, have between them three small ones, known as the "ocelli,"
arranged in a triangle. The structure of these two sets of eyes is quite
different. The ocelli appear to see as our eyes do. The lens throws an
inverted image on the back of the eye, so that with these eyes they must
see everything reversed, as we ourselves really do, though long practice
enables us to correct the impression. On the other hand, the compound
eyes consist of a number of facets, in some species as many as 20,000 in
each eye, and the prevailing impression among entomologists now is that
each facet receives the impression of one pencil of rays, that in fact
the image formed in a compound eye is a sort of mosaic. In that case,
vision by means of these eyes must be direct; and it is indeed difficult
to understand how an insect can obtain a correct impression when it
looks at the world with five eyes, three of which see everything
reversed, while the other two see things the right way up!
On the other hand, some regard each facet as an independent eye, in
which case many insects realise the epigram of Plato--
Thou lookest on the stars, my love,
Ah, would that I could be
Yon starry skies with thousand eyes,
That I might look on thee!
Even so, therefore, we only substitute one difficulty for another.
But this is not all. We have not only no proof that animals are confined
to our five senses, but there are strong reasons for believing that this
is not the case.
In the first place, many animals have organs which from their position,
structure, and rich supply of nerves, are evidently organs of sense; and
yet which do not appear to be adapted to any one of our five senses.
As already mentioned, the limits of hearing are reached when about
35,000 vibrations of the air strike on the drums of our ears. Light, as
was first conclusively demonstrated by our great countryman Young, is
the impression produced by vibration of the ether on the retina of the
eye. When 700 millions of millions of vibrations strike the eye in a
second, we see violet; and the colour changes as the number diminishes,
400 millions of millions giving us the impression of red.
Between 35 thousand and 400 millions of millions the interval is
immense, and it is obvious that there might be any number of sensations.
When we consider how greatly animals differ from us, alike in habits and
structure, is it not possible, nay, more, is it not likely that some of
these problematical organs are the seats of senses unknown to us, and
give rise to sensations of which we have no conception?
In addition to the capacity for receiving and perceiving, some animals
have the faculty of emitting light. In our country the glow-worm is the
most familiar case, though some other insects and worms have, at any
rate under certain conditions, the same power, and it is possible that
many others are really luminous, though with light which is invisible to
us. In warmer climates the Fire-fly, Lanthorn-fly, and many other
insects, shine with much greater brilliance, and in these cases the
glow seems to be a real love-light, like the lamp of Hero.
Many small marine animals, Medusæ, Crustacea, Worms, etc., are also
brilliantly luminous at night. Deep-sea animals are endowed also in many
cases with special luminous organs, to which I shall refer again.
SENSE OF DIRECTION
It has been supposed that animals possess also what has been called a
Sense of Direction. Many interesting cases are on record of animals
finding their way home after being taken a considerable distance. To
account for this fact it has been suggested that animals possess a sense
with which we are not endowed, or of which, at any rate, we possess only
a trace. The homing instinct of the pigeon has also been ascribed to the
same faculty. My brother Alfred, however, who has paid much attention to
pigeons, informs me that they are never taken any great distance at
once; but if they are intended to take a long flight, they are trained
to do so by stages.
Darwin suggested that it would be interesting to test the case by taking
animals in a close box, and then whirling them round rapidly before
letting them out. This is in fact done with cats in some parts of
France, when the family migrates, and is considered the only way of
preventing the cat from returning to the old home. Fabre has tried the
same thing with some wild Bees (Chalicodoma). He took some, marked them
on the back with a spot of white, and put them into a bag. He then
carried them a quarter of a mile, stopping at a point where an old cross
stands by the wayside, and whirled the bag rapidly round his head. While
he was doing so a good woman came by, who seemed not a little surprised
to find the Professor solemnly whirling a black bag round his head in
front of the cross; and, he fears, suspected him of Satanic practices.
He then carried his Bees a mile and a half in the opposite direction and
let them go. Three out of ten found their way home. He tried the same
experiment several times, in one case taking them a little over two
miles. On an average about a third of the Bees found their way home. "La
démonstration," says Fabre, "est suffisante. Ni les mouvements
enchevêtrés d'une rotation comme je l'ai décrite; ni l'obstacle de
collines à franchir et de bois à traverser; ni les embûches d'une voie
qui s'avance, rétrograde, et revient par un ample circuit, ne peuvent
troubler les Chalicodomes dépaysés et les empêcher de revenir au nid."
I must say, however, that I am not convinced. In the first place, the
distances were I think too short; and in the second, though it is true
that some of the Bees found their way home, nearly two-thirds failed to
do so. It would be interesting to try the experiment again, taking the
Bees say five miles. If they really possess any such sense, that
distance would be no bar to their return. I have myself experimented
with Ants, taking them about fifty yards from the nest, and I always
found that they wandered aimlessly about, having evidently not the
slightest idea of their way home. They certainly did not appear to
possess any "sense of direction."
NUMBER OF SPECIES
The total number of species may probably be safely estimated as at least
2,000,000, of which but a fraction have yet been described or named. Of
extinct species the number was probably at least as great. In the
geological history of the earth there have been at least twelve periods,
in each of which by far the greatest number were distinct. The Ancient
Poets described certain gifted mortals as having been privileged to
descend into the interior of the earth, and exercised their imagination
in recounting the wonders thus revealed. As in other cases, however, the
realities of Science have proved far more varied and surprising than the
dreams of fiction. Of these extinct species our knowledge is even more
incomplete than that of the existing species. But even of our
contemporaries it is not too much to say that, as in the case of
plants, there is not one the structure, habits, and life-history of
which are yet fully known to us. The male of the Cynips, which produces
the common King Charles Oak Apple, has only recently been discovered,
those of the root-feeding Aphides, which live in hundreds in every nest
of the yellow Meadow Ant (Lasius flavus) are still unknown; the habits
and mode of reproduction of the common Eel have only just been
discovered; and we may even say generally that many of the most
interesting recent discoveries have relation to the commonest and most
familiar animals.
IMPORTANCE OF THE SMALLER ANIMALS
Whatever pre-eminence Man may claim for himself, other animals have done
far more to affect the face of nature. The principal agents have not
been the larger or more intelligent, but rather the smaller, and
individually less important, species. Beavers may have dammed up many of
the rivers of British Columbia, and turned them into a succession of
pools or marshes, but this is a slight matter compared with the action
of earthworms and insects[17] in the creation of vegetable soil; of the
accumulation of animalcules in filling up harbours and lakes; or of
Zoophytes in the construction of coral islands.
Microscopic animals make up in number what they lack in size. Paris is
built of Infusoria. The Peninsula of Florida, 78,000 square miles in
extent, is entirely composed of coral debris and fragments of shells.
Chalk consists mainly of Foraminifera and fragments of shells deposited
in a deep sea. The number of shells required to make up a cubic inch is
almost incredible. Ehrenberg has estimated that of the Bilin polishing
slate which caps the mountain, and has a thickness of forty feet, a
cubic inch contains many hundred million shells of Infusoria.
In another respect these microscopic organisms are of vital importance.
Many diseases are now known, and others suspected, to be entirely due to
Bacteria and other minute forms of life (Microbes), which multiply
incredibly, and either destroy their victims, or after a while diminish
again in numbers. We live indeed in a cloud of Bacteria. At the
observatory of Montsouris at Paris it has been calculated that there are
about 80 in each cubic meter of air. Elsewhere, however, they are much
more numerous. Pasteur's researches on the Silkworm disease led him to
the discovery of Bacterium anthracis, the cause of splenic fever.
Microbes are present in persons suffering from cholera, typhus,
whooping-cough, measles, hydrophobia, etc., but as to their history and
connection with disease we have yet much to learn. It is fortunate,
indeed, that they do not all attack us.
In surgical cases, again, the danger of compound fractures and
mortification of wounds has been found to be mainly due to the presence
of microscopic organisms; and Lister, by his antiseptic treatment which
destroys these germs or prevents their access, has greatly diminished
the danger of operations, and the sufferings of recovery.
SIZE OF ANIMALS
In the size of animals we find every gradation from these atoms which
even in the most powerful microscopes appear as mere points, up to the
gigantic reptiles of past ages and the Whales of our present ocean. The
horned Ray or Skate is 25 feet in length, by 30 in width. The
Cuttle-fishes of our seas, though so hideous as to resemble a bad dream,
are too small to be formidable; but off the Newfoundland coast is a
species with arms sometimes 30 feet long, so as to be 60 feet from tip
to tip. The body, however, is small in proportion. The Giraffe attains a
height of over 20 feet; the Elephant, though not so tall, is more bulky;
the Crocodile reaches a length of over 20 feet, the Python of 60 feet,
the extinct Titanosaurus of the American Jurassic beds, the largest land
animal yet known to us, 100 feet in length and 30 in height; the
Whalebone Whale over 70 feet, Sibbald's Whale is said to have reached
80-90, which is perhaps the limit. Captain Scoresby indeed mentions a
Rorqual no less than 120 feet in length, but this is probably too great
an estimate.
COMPLEXITY OF ANIMAL STRUCTURE
The complexity of animal structure is even more marvellous than their
mere magnitude. A Caterpillar contains more than 2000 muscles. In our
own body are some 2,000,000 perspiration glands, communicating with the
surface by ducts having a total length of some 10 miles; while that of
the arteries, veins, and capillaries must be very great; the blood
contains millions of millions of corpuscles, each no doubt a complex
structure in itself; the rods in the retina, which are supposed to be
the ultimate recipient of light, are estimated at 30,000,000; and
Meinert has calculated that the gray matter of the brain is built up of
at least 600,000,000 cells. No verbal description, however, can do
justice to the marvellous complexity of animal structure, which the
microscope alone, and even that but faintly, can enable us to realise.
LENGTH OF LIFE
How little we yet know of the life-history of Animals is illustrated by
the vagueness of our information as to the age to which they live.
Professor Lankester[18] tells us that "the paucity and uncertainty of
observations on this class of facts is extreme." The Rabbit is said to
reach 10 years, the Dog and Sheep 10-12, the Pig 20, the Horse 30, the
Camel 100, the Elephant 200, the Greenland Whale 400 (?): among Birds,
the Parrot to attain 100 years, the Raven even more. The Atur Parrot
mentioned by Humboldt, talked, but could not be understood, because it
spoke in the language of an extinct Indian tribe. It is supposed from
their rate of growth that among Fish the Carp is said to reach 150
years; and a Pike, 19 feet long, and weighing 350 lbs., is said to have
been taken in Suabia in 1497 carrying a ring, on which was inscribed, "I
am the fish which was first of all put into the lake by the hands of the
Governor of the Universe, Frederick the Second, the 5th Oct. 1230." This
would imply an age of over 267 years. Many Reptiles are no doubt very
long-lived. A Tortoise is said to have reached 500 years. As regards the
lower animals, the greatest age on record is that of Sir J. Dalzell's
Sea Anemone, which lived for over 50 years. Insects are generally
short-lived; the Queen Bee, however, is said by Aristotle, whose
statement has not been confirmed by recent writers, to live 7 years. I
myself had a Queen Ant which attained the age of 15 years.
The May Fly (Ephemera) is celebrated as living only for a day, and has
given its name to all things short-lived. The statement usually made is,
indeed, very misleading, for in its larval condition the Ephemera lives
for weeks. Many writers have expressed surprise that in the perfect
state its life should be so short. It is, however, so defenceless, and,
moreover, so much appreciated by birds and fish, that unless they laid
their eggs very rapidly none would perhaps survive to continue the
species.
Many of these estimates are, as will be seen, very vague and doubtful,
so that we must still admit with Bacon that, "touching the length and
shortness of life in living creatures, the information which may be had
is but slender, observation is negligent, and tradition fabulous. In
tame creatures their degenerate life corrupteth them, in wild creatures
their exposing to all weathers often intercepteth them."
ON INDIVIDUALITY
When we descend still lower in the animal scale, the consideration of
this question opens out a very curious and interesting subject connected
with animal individuality. As regards the animals with which we are
most familiar no such question intrudes. Among quadrupeds and birds,
fishes and reptiles, there is no difficulty in deciding whether a given
organism is an individual, or a part of an individual. Nor does the
difficulty arise in the case of most insects. The Bee or Butterfly lays
an egg which develops successively into a larva and pupa, finally
producing Bee or Butterfly. In these cases, therefore, the egg, larva,
pupa, and perfect Insect, are regarded as stages in the life of a single
individual. In certain gnats, however, the larva itself produces young
larvæ, each of which develops into a gnat, so that the egg produces not
one gnat but many gnats.
The difficulty of determining what constitutes an individual becomes
still greater among the Zoophytes. These beautiful creatures in many
cases so closely resemble plants, that until our countryman Ellis proved
them to be animals, Crabbe was justified in saying--
Involved in seawrack here we find a race,
Which Science, doubting, knows not where to place;
On shell or stone is dropped the embryo seed,
And quickly vegetates a vital breed.
We cannot wonder that such organisms were long regarded as belonging to
the vegetable kingdom. The cups which terminate the branches contain,
however, an animal structure, resembling a small Sea Anemone, and
possessing arms which capture the food by which the whole colony is
nourished. Some of these cups, moreover, differ from the rest, and
produce eggs. These then we might be disposed to term ovaries. But in
many species they detach themselves from the group and lead an
independent existence. Thus we find a complete gradation from structures
which, regarded by themselves, we should unquestionably regard as mere
organs, to others which are certainly separate and independent beings.
[Illustration: Fig. 2.--Bougainvillea fruticosa; natural size. (After
Allman.)]
Fig. 2 represents, after Allman, a colony of Bougainvillea fruticosa of
the natural size. It is a British species, which is found growing on
buoys, floating timber, etc., and, says Allman, "When in health and
vigour, offers a spectacle unsurpassed in interest by any other
species--every branchlet crowned by its graceful hydranth, and budding
with Medusæ in all stages of development (Fig. 3), some still in the
condition of minute buds, in which no trace of the definite Medusa-form
can yet be detected; others, in which the outlines of the Medusa can be
distinctly traced within the transparent ectotheque (external layer);
others, again, just casting off this thin outer pellicle, and others
completely freed from it, struggling with convulsive efforts to break
loose from the colony, and finally launched forth in the full enjoyment
of their freedom into the surrounding water. I know of no form in which
so many of the characteristic features of a typical hydroid are more
finely expressed than in this beautiful species."
[Illustration: Fig. 3.--Bougainvillea fruticosa; magnified to show
development.]
Fig. 4 represents the Medusa or free form of this beautiful species.
[Illustration: Fig. 4.--Bougainvillea fruticosa, Medusa-form.]
If we pass to another great group of Zoophytes, that of the
Jelly-fishes, we have a very similar case. For our first knowledge of
the life-history of these Zoophytes we are indebted to the Norwegian
naturalist Sars. Take, for instance, the common Jelly-fish (Medusa
aurita) (Fig. 5) of our shores.
The egg is a pear-shaped body (_1_), covered with fine hairs, by the aid
of which it swims about, the broader end in front. After a while it
attaches itself, not as might have been expected by the posterior but by
the anterior extremity (_2_). The cilia then disappear, a mouth is
formed at the free end, tentacles, first four (_3_), then eight, and at
length as many as thirty (_4_), are formed, and the little creature
resembles in essentials the freshwater polyp (Hydra) of our ponds.
[Illustration: Fig. 5.--Medusa aurita, and progressive stages of
development.]
At the same time transverse wrinkles (_4_) are formed round the body,
first near the free extremity and then gradually descending. They become
deeper and deeper, and develop lobes or divisions one under the other,
as at _5_. After a while the top ring (and subsequently the others one
by one) detaches itself, swims away, and gradually develops into a
Medusa (_6_). Thus, then, the life-history is very similar to that of
the Hydroids, only that while in the Hydroids the fixed condition is the
more permanent, and the free swimming more transitory, in the Medusæ,
on the contrary, the fixed condition is apparently only a phase in the
production of the free swimming animal. In both the one and the other,
however, the egg gives rise not to one but to many mature animals.
Steenstrup has given to these curious phenomena, many other cases of
which occur among the lower animals, and to which he first called
attention, the name of alternations of generations.
In the life-history of Infusoria (so called because they swarm in most
animal or vegetable infusions) similar difficulties encounter us. The
little creatures, many of which are round or oval in form, from time to
time become constricted in the middle; the constriction becomes deeper
and deeper, and at length the two halves twist themselves apart and swim
away. In this case, therefore, there was one, and there are now two
exactly similar; but are these two individuals? They are not parent and
offspring--that is clear, for they are of the same age; nor are they
twins, for there is no parent. As already mentioned, we regard the
Caterpillar, Chrysalis, and Butterfly as stages in the life-history of
a single individual. But among Zoophytes, and even among some insects,
one larva often produces several mature forms. In some species these
mature forms remain attached to the larval stock, and we might be
disposed to regard the whole as one complex organism. But in others they
detach themselves and lead an independent existence.
These considerations then introduce much difficulty into our conception
of the idea of an Individual.
ANIMAL IMMORTALITY
But, further than this, we are confronted by by another problem. If we
regard a mass of coral as an individual because it arises by continuous
growth from a single egg, then it follows that some corals must be
thousands of years old.
Some of the lower animals may be cut into pieces, and each piece will
develop into an entire organism. In fact the realisation of the idea of
an individual gradually becomes more and more difficult, and the
continuity of existence, even among the highest animals, gradually
forces itself upon us. I believe that as we become more rational, as we
realise more fully the conditions of existence, this consideration is
likely to have important moral results.
It is generally considered that death is the common lot of all living
beings. But is this necessarily so? Infusoria and other unicellular
animals multiply by division. That is to say, if we watch one for a
certain time, we shall observe, as already mentioned, that a
constriction takes place, which grows gradually deeper and deeper, until
at last the two halves become quite detached, and each swims away
independently. The process is repeated over and over again, and in this
manner the species is propagated. Here obviously there is no birth and
no death. Such creatures may be killed, but they have no natural term of
life. They are, in fact, theoretically immortal. Those which lived
millions of years ago may have gone on dividing and subdividing, and in
this sense multitudes of the lower animals are millions of years old.
FOOTNOTES:
[15] Address to Microscopical Society, 1890.
[16] _Ants, Bees, and Wasps_, and _The Senses of Animals_.
[17] Prof. Drummond (_Tropical Africa_) dwells with great force on the
manner in which the soil of Central Africa is worked up by the White
Ants.
[18] Lankester, _Comparative Longevity_. See also Weismann, _Duration of
Life_.
CHAPTER IV
ON PLANT LIFE
Flower in the crannied wall,
I pluck you out of the crannies,
I hold you here, root and all, in my hand,
Little flower--but _if_ I could understand
What you are, root and all, and all in all,
I should know what God and man is.
TENNYSON.
CHAPTER IV
ON PLANT LIFE
We are told that in old days the Fairies used to give presents of
Flowers and Leaves to those whom they wished to reward, or whom they
loved best; and though these gifts were, it appears, often received with
disappointment, still it will probably be admitted that flowers have
contributed more to the happiness of our lives than either gold or
silver or precious stones; and that our happiest days have been spent
out-of-doors in the woods and fields, when we have
... found in every woodland way
The sunlight tint of Fairy Gold.[19]
To many minds Flowers acquired an additional interest when it was shown
that there was a reason for their colour, size, and form--in fact, for
every detail of their organisation. If we did but know all that the
smallest flower could tell us, we should have solved some of the
greatest mysteries of Nature. But we cannot hope to succeed--even if we
had the genius of Plato or Aristotle--without careful, patient, and
reverent study. From such an inquiry we may hope much; already we have
glimpses, enough to convince us that the whole history will open out to
us conceptions of the Universe wider and grander than any which the
Imagination alone would ever have suggested.
Attempts to explain the forms, colours, and other characteristics of
animals and plants are by no means new. Our Teutonic forefathers had a
pretty story which explained certain points about several common plants.
Balder, the God of Mirth and Merriment, was, characteristically enough,
regarded as deficient in the possession of immortality. The other
divinities, fearing to lose him, petitioned Thor to make him immortal,
and the prayer was granted on condition that every animal and plant
would swear not to injure him. To secure this object, Nanna, Balder's
wife, descended upon the earth. Loki, the God of Envy, followed her,
disguised as a crow (which at that time were white), and settled on a
little blue flower, hoping to cover it up, so that Nanna might overlook
it. The flower, however, cried out "forget-me-not, forget-me-not," and
has ever since been known under that name. Loki then flew up into an oak
and sat on a mistletoe. Here he was more successful. Nanna carried off
the oath of the oak, but overlooked the mistletoe. She thought, however,
and the divinities thought, that she had successfully accomplished her
mission, and that Balder had received the gift of immortality.
One day, supposing Balder proof, they amused themselves by shooting at
him, posting him against a Holly. Loki tipped an arrow with a piece of
Mistletoe, against which Balder was not proof, and gave it to Balder's
brother. This, unfortunately, pierced him to the heart, and he fell
dead. Some drops of his blood spurted on to the Holly, which accounts
for the redness of the berries; the Mistletoe was so grieved that she
has ever since borne fruit like tears; and the crow, whose form Loki had
taken, and which till then had been white, was turned black.
This pretty myth accounts for several things, but is open to fatal
objections.
Recent attempts to explain the facts of Nature are not less fascinating,
and, I think, more successful.
Why then this marvellous variety? this inexhaustible treasury of
beautiful forms? Does it result from some innate tendency in each
species? Is it intentionally designed to delight the eye of man? Or has
the form and size and texture some reference to the structure and
organisation, the habits and requirements of the whole plant?
I shall never forget hearing Darwin's paper on the structure of the
Cowslip and Primrose, after which even Sir Joseph Hooker compared
himself to Peter Bell, to whom
A primrose by a river's brim
A yellow primrose was to him,
And it was nothing more.
We all, I think, shared the same feeling, and found that the explanation
of the flower then given, and to which I shall refer again, invested it
with fresh interest and even with new beauty.
A regular flower, such, for instance, as a Geranium or a Pink, consists
of four or more whorls of leaves, more or less modified: the lowest
whorl is the Calyx, and the separate leaves of which it is composed,
which however are sometimes united into a tube, are called sepals; (2) a
second whorl, the corolla, consisting of coloured leaves called petals,
which, however, like those of the Calyx, are often united into a tube;
(3) of one or more stamens, consisting of a stalk or filament, and a
head or anther, in which the pollen is produced; and (4) a pistil, which
is situated in the centre of the flower, and at the base of which is the
Ovary, containing one or more seeds.
Almost all large flowers are brightly coloured, many produce honey, and
many are sweet-scented.
What, then, is the use and purpose of this complex organisation?
It is, I think, well established that the main object of the colour,
scent, and honey of flowers is to attract insects, which are of use to
the plant in carrying the pollen from flower to flower.
In many species the pollen is, and no doubt it originally was in all,
carried by the air. In these cases the chance against any given grain of
pollen reaching the pistil of another flower of the same species is of
course very great, and the quantity of pollen required is therefore
immense.
In species where the pollen is wind-borne as in most of our trees--firs,
oaks, beech, ash, elm, etc., and many herbaceous plants, the flowers are
as a rule small and inconspicuous, greenish, and without either scent or
honey. Moreover, they generally flower early, so that the pollen may not
be intercepted by the leaves, but may have a better chance of reaching
another flower. And they produce an immense quantity of pollen, as
otherwise there would be little chance that any would reach the female
flower. Every one must have noticed the clouds of pollen produced by
the Scotch Fir. When, on the contrary, the pollen is carried by insects,
the quantity necessary is greatly reduced. Still it has been calculated
that a Peony flower produces between 3,000,000 and 4,000,000 pollen
grains; in the Dandelion, which is more specialised, the number is
reduced to about 250,000; while in such a flower as the Dead-nettle it
is still smaller.
The honey attracts the insects; while the scent and colour help them to
find the flowers, the scent being especially useful at night, which is
perhaps the reason why evening flowers are so sweet.
It is to insects, then, that flowers owe their beauty, scent, and
sweetness. Just as gardeners, by continual selection, have added so much
to the beauty of our gardens, so to the unconscious action of insects is
due the beauty, scent, and sweetness of the flowers of our woods and
fields.
Let us now apply these views to a few common flowers. Take, for
instance, the White Dead-nettle.
The corolla of this beautiful and familiar flower (Fig. 6) consists of
a narrow tube, somewhat expanded at the upper end (Fig. 7), where the
lower lobe forms a platform, on each side of which is a small projecting
tooth (Fig. 8, _m_). The upper portion of the corolla is an arched hood
(_co_), under which lie four anthers (_a a_), in pairs, while between
them, and projecting somewhat downwards, is the pointed pistil (_st_);
the tube at the lower part contains honey, and above the honey is a row
of hairs running round the tube.
[Illustration: Fig. 6--White Dead-nettle.]
Now, why has the flower this peculiar form? What regulates the length of
the tube? What is the use of the arch? What lesson do the little teeth
teach us? What advantage is the honey to the flower? Of what use is the
fringe of hairs? Why does the stigma project beyond the anthers? Why is
the corolla white, while the rest of the plant is green?
[Illustration: Fig. 7.]
[Illustration: Fig. 8.]
The honey of course serves to attract the Humble Bees by which the
flower is fertilised, and to which it is especially adapted; the white
colour makes the flower more conspicuous; the lower lip forms the stage
on which the Bees may alight; the length of the tube is adapted to that
of their proboscis; its narrowness and the fringe of fine hairs exclude
small insects which might rob the flower of its honey without performing
any service in return; the arched upper lip protects the stamens and
pistil, and prevents rain-drops from choking up the tube and washing
away the honey; the little teeth are, I believe, of no use to the
flower in its present condition, they are the last relics of lobes once
much larger, and still remaining so in some allied species, but which in
the Dead-nettle, being no longer of any use, are gradually disappearing;
the height of the arch has reference to the size of the Bee, being just
so much above the alighting stage that the Bee, while sucking the honey,
rubs its back against the hood and thus comes in contact first with the
stigma and then with the anthers, the pollen-grains from which adhere to
the hairs on the Bee's back, and are thus carried off to the next flower
which the Bee visits, when some of them are then licked off by the
viscid tip of the stigma.[20]
[Illustration: Fig. 9.]
[Illustration: Fig. 10.]
[Illustration: Fig. 11.]
In the Salvias, the common blue Salvia of our gardens, for instance,--a
plant allied to the Dead-nettle,--the flower (Fig. 9) is constructed on
the same plan, but the arch is much larger, so that the back of the Bee
does not nearly reach it. The stamens, however, have undergone a
remarkable modification. Two of them have become small and functionless.
In the other two the anthers or cells producing the pollen, which in
most flowers form together a round knob or head at the top of the
stamen, are separated by a long arm, which plays on the top of the
stamen as on a hinge. Of these two arms one hangs down into the tube,
closing the passage, while the other lies under the arched upper lip.
When the Bee pushes its proboscis down the tube (Fig. 11) it presses the
lower arm to one side, and the upper arm consequently descends, tapping
the Bee on the back, and dusting it with pollen. When the flower is a
little older the pistil (Fig. 9, _p_) has elongated so that the stigma
(Fig. 10, _st_) touches the back of the Bee and carries off some of the
pollen. This sounds a little complicated, but is clear enough if we take
a twig or stalk of grass and push it down the tube, when one arm of each
of the two larger stamens will at once make its appearance. It is one of
the most beautiful pieces of plant mechanism which I know, and was first
described by Sprengel, a poor German schoolmaster.
SNAPDRAGON
At first sight it may seem an objection to the view here advocated that
the flowers in some species--as, for instance, the common Snapdragon
(Antirrhinum), which, according to the above given tests, ought to be
fertilised by insects--are entirely closed. A little consideration,
however, will suggest the reply. The Snapdragon is especially adapted
for fertilisation by Humble Bees. The stamens and pistil are so
arranged that smaller species would not effect the object. It is
therefore an advantage that they should be excluded, and in fact they
are not strong enough to move the spring. The Antirrhinum is, so to
speak, a closed box, of which the Humble Bees alone possess the key.
FURZE, BROOM, AND LABURNUM
Other flowers such as the Furze, Broom, Laburnum, etc., are also opened
by Bees. The petals lock more or less into one another, and the flower
remains at first closed. When, however, the insect alighting on it
presses down the keel, the flower bursts open, and dusts it with pollen.
SWEET PEA
In the above cases the flower once opened does not close again. In
others, such as the Sweet Pea and the Bird's-foot Lotus, Nature has
been more careful. When the Bee alights it clasps the "wings" of the
flower with its legs, thus pressing them down; they are, however, locked
into the "keel," or lower petal, which accordingly is also forced down,
thus exposing the pollen which rubs against, and part of which sticks
to, the breast of the Bee. When she leaves the flower the keel and wings
rise again, thus protecting the rest of the pollen and keeping it ready
until another visitor comes. It is easy to carry out the same process
with the fingers.
[Illustration: Fig. 12. Fig. 13.
Flower and Pollen of Primrose]
PRIMULA
In the Primrose and Cowslip, again, we find quite a different plan. It
had long been known that if a number of Cowslips or Primroses are
examined, about half would be found to have the stigma at the top of the
tube and the stamens half way down, while in the other half the stamens
are at the top and the stigma half way down. These two forms are about
equally numerous, but never occur on the same stock. They have been long
known to children and gardeners, who call them thrum-eyed and pin-eyed.
Mr. Darwin was the first to explain the significance of this curious
difference. It cost him several years of patient labour, but when once
pointed out it is sufficiently obvious. An insect thrusting its
proboscis down a primrose of the long-styled form (Fig. 12) would dust
its proboscis at a part (_a_) which, when it visited a short-styled
flower (Fig. 13), would come just opposite the head of the pistil
(_st_), and could not fail to deposit some of the pollen on the stigma.
Conversely, an insect visiting a short-styled plant would dust its
proboscis at a part farther from the tip; which, when the insect
subsequently visited a long-styled flower, would again come just
opposite to the head of the pistil. Hence we see that by this beautiful
arrangement insects must carry the pollen of the long-styled form to the
short-styled, and _vice versâ_.
The economy of pollen is not the only advantage which plants derive from
these visits of Insects. A second and scarcely less important is that
they tend to secure "cross fertilisation"; that is to say, that the seed
shall be fertilised by pollen from another plant. The fact that "cross
fertilisation" is of advantage to the plant doubtless also explains the
curious arrangement that in many plants the stamen and pistil do not
mature at the same time--the former having shed their pollen before the
pistil is mature; or, which happens less often, the pistil having
withered before the pollen is ripe. In most Geraniums, Pinks, etc., for
instance, and many allied species, the stamens ripen first, and are
followed after an interval by the pistil.
THE NOTTINGHAM CATCHFLY
The Nottingham Catchfly (Silene nutans) is a very interesting case. The
flower is adapted to be fertilised by Moths. Accordingly it opens
towards evening, and as is generally the case with such flowers, is pale
in colour, and sweet-scented. There are two sets of stamens, five in
each set. The first evening that the flower opens one set of stamens
ripen and expose their pollen. Towards morning these wither away, the
flower shrivels up, ceases to emit scent, and looks as if it were faded.
So it remains all next day. Towards evening it reopens, the second set
of stamens have their turn, and the flower again becomes fragrant. By
morning, however, the second set of stamens have shrivelled, and the
flower is again asleep. Finally on the third evening it reopens for the
last time, the long spiral stigmas expand, and can hardly fail to be
fertilised with the pollen brought by Moths from other flowers.
THE HEATH
In the hanging flowers of Heaths the stamens form a ring, and each one
bears two horns. When the Bee inserts its proboscis into the flower to
reach the honey, it is sure to press against one of these horns, the
ring is dislocated, and the pollen falls on to the head of the insect.
In fact, any number of other interesting cases might be mentioned.
BEES AND FLIES
Bees are intelligent insects, and would soon cease to visit flowers
which did not supply them with food. Flies, however, are more stupid,
and are often deceived. Thus in our lovely little Parnassia, five of the
ten stamens have ceased to produce pollen, but are prolonged into
fingers, each terminating in a shining yellow knob, which looks exactly
like a drop of honey, and by which Flies are continually deceived.
Paris quadrifolia also takes them in with a deceptive promise of the
same kind. Some foreign plants have livid yellow and reddish flowers,
with a most offensive smell, and are constantly visited by Flies, which
apparently take them for pieces of decaying meat.
[Illustration: Fig. 14.--Arum.]
The flower of the common Lords and Ladies (Arum) of our hedges is a very
interesting case. The narrow neck bears a number of hairs pointing
downwards. The stamens are situated above the stigma, which comes to
maturity first. Small Flies enter the flower apparently for shelter, but
the hairs prevent them from returning, and they are kept captive until
the anthers have shed their pollen. Then, when the Flies have been well
dusted, the hairs shrivel up, leaving a clear road, and the prisoners
are permitted to escape. The tubular flowers of Aristolochia offer a
very similar case.
PAST HISTORY OF FLOWERS
If the views here advocated are correct, it follows that the original
flowers were small and green, as wind-fertilised flowers are even now.
But such flowers are inconspicuous. Those which are coloured, say yellow
or white, are of course much more visible and more likely to be visited
by insects. I have elsewhere given my reasons for thinking that under
these circumstances some flowers became yellow, that some of them became
white, others subsequently red, and some finally blue. It will be
observed that red and blue flowers are as a rule highly specialised,
such as Aconites and Larkspurs as compared with Buttercups; blue
Gentians as compared with yellow, etc. I have found by experiment that
Bees are especially partial to blue and pink.
Tubular flowers almost always, if not always, contain honey, and are
specially suited to Butterflies and Moths, Bees and Flies. Those which
are fertilised by Moths generally come out in the evening, are often
very sweetly scented, and are generally white or pale yellow, these
colours being most visible in the twilight.
Aristotle long ago noticed the curious fact that in each journey Bees
confine themselves to some particular flower. This is an economy of
labour to the Bee, because she has not to vary her course of proceeding.
It is also an advantage to the plants, because the pollen is carried
from each flower to another of the same species, and is therefore less
likely to be wasted.
FRUITS AND SEEDS
After the flower comes the seed, often contained in a fruit, and which
itself encloses the future plant. Fruits and seeds are adapted for
dispersion, beautifully and in various ways: some by the wind, being
either provided with a wing, as in the fruits of many trees--Sycamores,
Ash, Elms, etc.; or with a hairy crown or covering, as with Thistles,
Dandelions, Willows, Cotton plant, etc.
Some seeds are carried by animals; either as food--such as most edible
fruits and seeds, acorns, nuts, apples, strawberries, raspberries,
blackberries, plums, grasses, etc.--or involuntarily, the seeds having
hooked hairs or processes, such as burrs, cleavers, etc.
Some seeds are scattered by the plants themselves, as, for instance,
those of many Geraniums, Violets, Balsams, Shamrocks, etc. Our little
Herb Robert throws its seeds some 25 feet.
Some seeds force themselves into the ground, as those of certain
grasses, Cranes'-bills (Erodiums), etc.
Some are buried by the parent plants, as those of certain clovers,
vetches, violets, etc.
Some attach themselves to the soil, as those of the Flax; or to trees,
as in the case of the Mistletoe.
LEAVES
Again, as regards the leaves there can, I think, be no doubt that
similar considerations of utility are applicable. Their forms are
almost infinitely varied. To quote Ruskin's vivid words, they "take all
kinds of strange shapes, as if to invite us to examine them.
Star-shaped, heart-shaped, spear-shaped, arrow-shaped, fretted, fringed,
cleft, furrowed, serrated, sinuated, in whorls, in tufts, in spires, in
wreaths, endlessly expressive, deceptive, fantastic, never the same from
foot-stalk to blossom, they seem perpetually to tempt our watchfulness
and take delight in outstepping our wonder."
But besides these differences of mere form, there are many others: of
structure, texture, and surface; some are scented or have a strong
taste, or acrid juice, some are smooth, others hairy; and the hairs
again are of various kinds.
I have elsewhere[21] endeavoured to explain some of the causes which
have determined these endless varieties. In the Beech, for instance
(Fig. 15), the leaf has an area of about 3 square inches. The distance
between the buds is about 1-1/4 inch, and the leaves lie in the general
plane of the branch, which bends slightly at each internode. The basal
half of the leaf fits the swell of the twig, while the upper half
follows the edge of the leaf above; and the form of the inner edge being
thus determined, decides that of the outer one also.
[Illustration: Fig. 15.--Beech.]
The weight, and consequently the size of the leaf, is limited by the
strength of the twig; and, again, in a climate such as ours it is
important to plants to have their leaves so arranged as to secure the
maximum of light. Hence in leaves which lie parallel to the plane of the
boughs, as in the Beech, the width depends partly on the distance
between the buds; if the leaves were broader, they would overlap, if
they were narrower, space would be wasted. Consequently the width being
determined by the distance between the buds, and the size depending on
the weight which the twig can safely support, the length also is
determined. This argument is well illustrated by comparing the leaves of
the Beech with those of the Spanish Chestnut. The arrangement is
similar, and the distance between the buds being about the same, so is
the width of the leaves. But the terminal branches of the Spanish
Chestnut being much stronger, the leaves can safely be heavier; hence
the width being fixed, they grow in length and assume the well-known and
peculiar sword-blade shape.
In the Sycamores, Maples (Fig. 16), and Horse-Chestnuts the arrangement
is altogether different. The shoots are stiff and upright with leaves
placed at right angles to the branches instead of being parallel to
them. The leaves are in pairs and decussate with one another; while the
lower ones have long petioles which bring them almost to the level of
the upper pairs, the whole thus forming a beautiful dome.
For leaves arranged as in the Beech the gentle swell at the base is
admirably suited; but in a crown of leaves such as those of the
Sycamore, space would be wasted, and it is better that they should
expand at once, so soon as their stalks have carried them free from the
upper and inner leaves.
[Illustration: Fig. 16.--Acer platanoides.]
In the Black Poplar the arrangement of the leaves is again quite
different. The leaf stalk is flattened, so that the leaves hang
vertically. In connection with this it will be observed that while in
most leaves the upper and under surfaces are quite unlike, in the Black
Poplar on the contrary they are very similar. The stomata or breathing
holes, moreover, which in the leaves of most trees are confined to the
under surface, are in this species nearly equally numerous on both.
The "Compass" Plant of the American prairies, a plant not unlike a small
sunflower, is another species with upright leaves, which growing in the
wide open prairies tend to point north and south, thus exposing both
surfaces equally to the light and heat. Such a position also affects the
internal structure of the leaf, the two sides becoming similar in
structure, while in other cases the upper and under surfaces are very
different.
In the Yew the leaves are inserted close to one another, and are linear;
while in the Box they are further apart and broader. In other cases the
width of the leaves is determined by what botanists call the
"Phyllotaxy." Some plants have the leaves opposite, each pair being at
right angles with the pairs above and below.
In others they are alternate, and arranged round the stem in a spiral.
In one very common arrangement the sixth leaf stands directly over the
first, the intermediate ones forming a spiral which has passed twice
round the stem. This, therefore, is known as the 2/5 arrangement. Common
cases are 1/2, 1/3, 2/5, 3/8, and 5/13. In the first the leaves are
generally broad, in the 3/8 arrangement they are elliptic, in the 5/13
and more complicated arrangements nearly linear. The Willows afford a
very interesting series. Salix herbacea has the 1/3 arrangement and
rounded leaves, Salix caprea elliptic leaves and 2/5, Salix pentandra
lancet-shaped leaves and 3/8, and S. incana linear leaves and a 5/13
arrangement. The result is that whether the series consists of 2, 3, 5,
8, or 13 leaves, in every case, if we look perpendicularly at a twig the
leaves occupy the whole circle.
In herbaceous plants upright leaves as a rule are narrow, which is
obviously an advantage, while prostrate ones are broad.
[Illustration: AQUATIC VEGETATION, BRAZIL. _To face page 145._]
AQUATIC PLANTS
Many aquatic plants have two kinds of leaves; some more or less rounded,
which float on the surface; and others cut up into narrow segments,
which remain below. The latter thus present a greater extent of surface.
In air such leaves would be unable even to support their own weight,
much less to resist the force of the wind. In still air, however, for
the same reason, finely-divided leaves may be an advantage, while in
exposed positions compact and entire leaves are more suitable. Hence
herbaceous plants tend to have divided, bushes and trees entire, leaves.
There are many cases when even in the same family low and herb-like
species have finely-cut leaves, while in shrubby or ligneous ones they
more or less resemble those of the Laurel or Beech.
These considerations affect trees more than herbs, because trees stand
more alone, while herbaceous plants are more affected by surrounding
plants. Upright leaves tend to be narrow, as in the case of grasses;
horizontal leaves, on the contrary, wider. Large leaves are more or less
broken up into leaflets, as in the Ash, Mountain-Ash, Horse-Chestnut,
etc.
The forms of leaves depend also much on the manner in which they are
packed into the buds.
The leaves of our English trees, as I have already said, are so arranged
as to secure the maximum of light; in very hot countries the reverse is
the case. Hence, in Australia, for instance, the leaves are arranged not
horizontally, but vertically, so as to present, not their surfaces, but
their edges, to the sun. One English plant, a species of lettuce, has
the same habit. This consideration has led also to other changes. In
many species the leaves are arranged directly under, so as to shelter,
one another. The Australian species of Acacia have lost their true
leaves, and the parts which in them we generally call leaves are in
reality vertically-flattened leaf stalks.
In other cases the stem itself is green, and to some extent replaces the
leaves. In our common Broom we see an approach to this, and the same
feature is more marked in Cactus. Or the leaves become fleshy, thus
offering, in proportion to their volume, a smaller surface for
evaporation. Of this the Stonecrops, Mesembryanthemum, etc., are
familiar instances. Other modes of checking transpiration and thus
adapting plants to dry situations are by the development of hairs, by
the formation of chalky excretions, by the sap becoming saline or
viscid, by the leaf becoming more or less rolled up, or protected by a
covering of varnish.
Our English trees are for the most part deciduous. Leaves would be
comparatively useless in winter when growth is stopped by the cold;
moreover, they would hold the snow, and thus cause the boughs to be
broken down. Hence perhaps the glossiness of Evergreen leaves, as, for
instance, of the Holly, from which the snow slips off. In warmer
climates trees tend to retain their leaves, and some species which are
deciduous in the north become evergreen, or nearly so, in the south of
Europe. Evergreen leaves are as a rule tougher and thicker than those
which drop off in autumn; they require more protection from the weather.
But some evergreen leaves are much longer lived than others; those of
the Evergreen Oak do not survive a second year, those of the Scotch Pine
live for three, of the Spruce Fir, Yew, etc., for eight or ten, of the
Pinsapo even eighteen. As a general rule the Conifers with short leaves
keep them on for several years, those with long ones for fewer, the
length of the leaf being somewhat in the inverse ratio to the length of
its life; but this is not an invariable criterion, as other
circumstances also have to be taken into consideration.
Leaves with strong scent, aromatic taste, or acrid juice, are
characteristic of dry regions, where they run especial danger of being
eaten, and where they are thus more or less effectively protected.
ON HAIRS
The hairs of plants are useful in various ways. In some cases (1) they
keep off superfluous moisture; in others (2) they prevent too rapid
evaporation; in some (3) they serve as a protection against too glaring
light; in some (4) they protect the plant from browsing quadrupeds; in
others (5) from being eaten by insects; or, (6) serve as a quickset
hedge to prevent access to the flowers.
In illustration of the first case I may refer to many alpine plants, the
well-known Edelweiss, for instance, where the woolly covering of hairs
prevents the "stomata," or minute pores leading into the interior of the
leaf, from being clogged up by rain, dew, or fog, and thus enable them
to fulfil their functions as soon as the sun comes out.
As regards the second case many desert and steppe-plants are covered
with felty hairs, which serve to prevent too rapid evaporation and
consequent loss of moisture.
The woolly hairy leaves of the Mulleins (Verbascum) doubtless tend to
protect them from being eaten, as also do the spines of Thistles, and
those of Hollies, which, be it remarked, gradually disappear on the
upper leaves which browsing quadrupeds cannot reach.
I have already alluded to the various ways in which flowers are adapted
to fertilisation by insects. But Ants and other small creeping insects
cannot effectually secure this object. Hence it is important that they
should be excluded, and not allowed to carry off the honey, for which
they would perform no service in return. In many cases, therefore, the
opening of the flower is either contracted to a narrow passage, or is
itself protected by a fringe of hairs. In others the peduncle, or the
stalk of the plant, is protected by a hedge, or chevaux de frise, of
hairs.
In this connection I might allude to the many plants which are more or
less viscid. This also is in most cases a provision to preclude creeping
insects from access to the flowers.
There are various other kinds of hairs to which I might refer--glandular
hairs, secretive hairs, absorbing hairs, etc. It is marvellous how
beautifully the form and structure of leaves is adapted to the habits
and requirements of the plants, but I must not enlarge further on this
interesting subject.
The time indeed will no doubt come when we shall be able to explain
every difference of form and structure, almost infinite as these
differences are.
INFLUENCE OF SOIL
The character of the vegetation is of course greatly influenced by that
of the soil. In this respect granitic and calcareous regions offer
perhaps the best marked contrast.
There are in Switzerland two kinds of Rhododendrons, very similar in
their flowers, but contrasted in their leaves: Rhododendron hirsutum
having them hairy at the edges as the name indicates; while in R.
ferrugineum they are rolled, but not hairy, at the edges, and become
ferrugineous on the lower side. This species occurs in the granitic
regions, where R. hirsutum does not grow.
The Yarrows (Achillea) afford us a similar case. Achillea atrata and A.
moschata will live either on calcareous or granitic soil, but in a
district where both occur, A. atrata grows so much the more vigorously
of the two if the soil is calcareous that it soon exterminates A.
moschata; while in granite districts, on the contrary, A. moschata is
victorious and A. atrata disappears.
Every keen sportsman will admit that a varied "bag" has a special charm,
and the botanist in a summer's walk may see at least a hundred plants in
flower, all with either the interest of novelty, or the charm of an old
friend.
ON SEEDLINGS
In many cases the Seedlings afford us an interesting insight into the
former condition of the plant. Thus the leaves of the Furze are reduced
to thorns; but those of the Seedling are herbaceous and trifoliate like
those of the Herb Genet and other allied species, subsequent ones
gradually passing into spines. This is evidence that the ancestors of
the Furze bore leaves.
Plants may be said to have their habits as well as animals.
SLEEP OF PLANTS
Many flowers close their petals during rain; the advantage of which is
that it prevents the honey and pollen from being spoilt or washed away.
Everybody, however, has observed that even in fine weather certain
flowers close at particular hours. This habit of going to sleep is
surely very curious. Why should flowers do so? In animals we can better
understand it; they are tired and require rest. But why should flowers
sleep? Why should some flowers do so, and not others? Moreover,
different flowers keep different hours. The Daisy opens at sunrise and
closes at sunset, whence its name "day's-eye." The Dandelion (Leontodon)
is said to open about seven and to close about five; Arenaria rubra to
be open from nine to three; the White Water Lily (Nymphæa), from about
seven to four; the common Mouse-ear Hawk-weed (Hieracium) from eight to
three; the Scarlet Pimpernel (Anagallis) to waken at seven and close
soon after two; Tragopogon pratensis to open at four in the morning, and
close just before twelve, whence its English name, "John go to bed at
noon." Farmers' boys in some parts are said to regulate their dinner
time by it. Other flowers, on the contrary, open in the evening.
Now it is obvious that flowers which are fertilised by night-flying
insects would derive no advantage from being open by day; and on the
other hand, that those which are fertilised by bees would gain nothing
by being open at night. Nay it would be a distinct disadvantage, because
it would render them liable to be robbed of their honey and pollen, by
insects which are not capable of fertilising them. I have ventured to
suggest then that the closing of flowers may have reference to the
habits of insects, and it may be observed also in support of this, that
wind-fertilised flowers do not sleep; and that many of those flowers
which attract insects by smell, open and emit their scent at particular
hours; thus Hesperis matronalis and Lychnis vespertina smell in the
evening, and Orchis bifolia is particularly sweet at night.
But it is not the flowers only which "sleep" at night; in many species
the leaves also change their position, and Darwin has given strong
reasons for considering that the object is to check transpiration and
thus tend to a protection against cold.
BEHAVIOUR OF LEAVES IN RAIN
The behaviour of plants with reference to rain affords many points of
much interest. The Germander Speedwell (Veronica) has two strong rows of
hairs, the Chickweed (Stellaria) one, running down the stem and thus
conducting the rain to the roots. Plants with a main tap-root, like the
Radish or the Beet, have leaves sloping inwards so as to conduct the
rain towards the axis of the plant, and consequently to the roots;
while, on the contrary, where the roots are spreading the leaves slope
outwards.
In other cases the leaves hold the rain or dew drops. Every one who has
been in the Alps must have noticed how the leaves of the Lady's Mantle
(Alchemilla) form little cups containing each a sparkling drop of icy
water. Kerner has suggested that owing to these cold drops, the cattle
and sheep avoid the leaves.
MIMICRY
In many cases plants mimic others which are better protected than
themselves. Thus Matricaria Chamomilla mimics the true Chamomile, which
from its bitterness is not eaten by quadrupeds. Ajuga Chamæpitys mimics
Euphorbia Cyparissias, with which it often grows, and which is protected
by its acrid juice. The most familiar case, however, is that of the
Stinging and the Dead Nettles. They very generally grow together, and
though belonging to quite different families are so similar that they
are constantly mistaken for one another. Some Orchids have a curious
resemblance to insects, after which they have accordingly been named the
Bee Orchis, Fly Orchis, Butterfly Orchis, etc., but it has not yet been
satisfactorily shown what advantage the resemblance is to the plant.
ANTS AND PLANTS
The transference of pollen from plant to plant is by no means the only
service which insects render.
Ants, for instance, are in many cases very useful to plants. They
destroy immense numbers of caterpillars and other insects. Forel
observing a large Ants' nest counted more than 28 insects brought in as
food per minute. In some cases Ants attach themselves to particular
trees, constituting a sort of bodyguard. A species of Acacia, described
by Belt, bears hollow thorns, while each leaflet produces honey in a
crater-formed gland at the base, as well as a small, sweet, pear-shaped
body at the tip. In consequence it is inhabited by myriads of a small
ant, which nests in the hollow thorns, and thus finds meat, drink, and
lodging all provided for it. These ants are continually roaming over the
plant, and constitute a most efficient bodyguard, not only driving off
the leaf-eating ants, but, in Belt's opinion, rendering the leaves less
liable to be eaten by herbivorous mammalia. Delpino mentions that on one
occasion he was gathering a flower of Clerodendrum, when he was himself
suddenly attacked by a whole army of small ants.
INSECTIVOROUS PLANTS
In the cases above mentioned the relation between flowers and insects is
one of mutual advantage. But this is by no means an invariable rule.
Many insects, as we all know, live on plants, but it came upon botanists
as a surprise when our countryman Ellis first discovered that some
plants catch and devour insects. This he observed in a North American
plant, Dionsea, the leaves of which are formed something like a
rat-trap, with a hinge in the middle, and a formidable row of spines
round the edge. On the surface are a few very sensitive hairs, and the
moment any small insect alights on the leaf and touches one of these
hairs the two halves of the leaf close up quickly and catch it. The
surface then throws out a glutinous secretion, by means of which the
leaf sucks up the nourishment contained in the insect.
Our common Sun-dews (Drosera) are also insectivorous, the prey being in
their case captured by glutinous hairs. Again, the Bladderwort
(Utricularia), a plant with pretty yellow flowers, growing in pools and
slow streams, is so called because it bears a great number of bladders
or utricles, each of which is a real miniature eel-trap, having an
orifice guarded by a flap opening inwards which allows small water
animals to enter, but prevents them from coming out again. The
Butterwort (Pinguicula) is another of these carnivorous plants.
MOVEMENTS OF PLANTS
While considering Plant life we must by no means confine our attention
to the higher orders, but must remember also those lower groups which
converge towards the lower forms of animals, so that in the present
state of our knowledge the two cannot always be distinguished with
certainty. Many of them differ indeed greatly from the ordinary
conception of a plant. Even the comparatively highly organised Sea-weeds
multiply by means of bodies called spores, which an untrained observer
would certainly suppose to be animals. They are covered by vibratile
hairs or "cilia," by means of which they swim about freely in the water,
and even possess a red spot which, as being especially sensitive to
light, may be regarded as an elementary eye, and with the aid of which
they select some suitable spot, to which they ultimately attach
themselves.
It was long considered as almost a characteristic of plants that they
possessed no power of movement. This is now known to be an error. In
fact, as Darwin has shown, every growing part of a plant is in continual
and even constant rotation. The stems of climbing plants make great
sweeps, and in other cases, when the motion is not so apparent, it
nevertheless really exists. I have already mentioned that many plants
change the position of their leaves or flowers, or, as it is called,
sleep at night.
The common Dandelion raises its head when the florets open, opens and
shuts morning and evening, then lies down again while the seeds are
ripening, and raises itself a second time when they are ready to be
carried away by the wind.
Valisneria spiralis is a very interesting case. It is a native of
European rivers, and the female flower has a long spiral stalk which
enables it to float on the surface of the water. The male flowers have
no stalks, and grow low down on the plant. They soon, however, detach
themselves altogether, rise to the surface, and thus are enabled to
fertilise the female flowers among which they float. The spiral stalk of
the female flower then contracts and draws it down to the bottom of the
water so that the seeds may ripen in safety. Many plants throw or bury
their seeds.
The sensitive plants close their leaves when touched, and the leaflets
of Desmodium gyrans are continually revolving. I have already mentioned
that the spores of sea-weeds swim freely in the water by means of cilia.
Some microscopic plants do so throughout a great part of their lives.
A still lower group, the Myxomycetes, which resemble small, more or less
branched, masses of jelly, and live in damp soil, among decaying
leaves, under bark and in similar moist situations, are still more
remarkably animal like. They are never fixed, but in almost continual
movement, due to differences of moisture, warmth, light, or chemical
action. If, for instance, a moist body is brought into contact with one
of their projections, or "pseudopods," the protoplasm seems to roll
itself in that direction, and so the whole organism gradually changes
its place. So again, while a solution of salt, carbonate of potash, or
saltpetre causes them to withdraw from the danger, an infusion of sugar,
or tan, produces a flow of protoplasm towards the source of nourishment.
In fact, in the same way it rolls over and round its food, absorbing
what is nutritious as it passes along. In cold weather they descend into
the soil, and one of them (Oethalium), which lives in tan pits,
descends in winter to a depth of several feet. When about to fructify it
changes its habits, seeks the light instead of avoiding it, climbs
upwards, and produces its fruit above ground.
IMPERFECTION OF OUR KNOWLEDGE
The total number of living species of plants may be roughly estimated at
500,000, and there is not one, of which we can say that the structure,
uses, and life-history are yet fully known to us. Our museums contain
large numbers which botanists have not yet had time to describe and
name. Even in our own country not a year passes without some additional
plant being discovered; as regards the less known regions of the earth
not half the species have yet been collected. Among the Lichens and
Fungi especially many problems of their life-history, some, indeed, of
especial importance to man, still await solution.
Our knowledge of the fossil forms, moreover, falls far short even of
that of existing species, which, on the other hand, they must have
greatly exceeded in number. Every difference of form, structure, and
colour has doubtless some cause and explanation, so that the field for
research is really inexhaustible.
FOOTNOTES:
[19] Thomson.
[20] Lubbock, _Flowers and Insects_.
[21] _Flowers, Fruits, and Leaves._
CHAPTER V
WOODS AND FIELDS
"By day or by night, summer or winter, beneath trees the heart
feels nearer to that depth of life which the far sky means. The
rest of spirit, found only in beauty, ideal and pure, comes
there because the distance seems within touch of thought."
JEFFERIES.
CHAPTER V
WOODS AND FIELDS
Rural life, says Cicero, "is not delightful by reason of cornfields only
and meadows, and vineyards and groves, but also for its gardens and
orchards, for the feeding of cattle, the swarms of bees, and the variety
of all kinds of flowers." Bacon considered that a garden is "the
greatest refreshment to the spirits of man, without which buildings and
palaces are but gross handyworks, and a man shall ever see, that when
ages grow to civility and elegancy men come to build stately sooner than
to garden finely, as if gardening were the greater perfection."
No doubt "the pleasure which we take in a garden is one of the most
innocent delights in human life."[22] Elsewhere there may be scattered
flowers, or sheets of colour due to one or two species, but in gardens
one glory follows another. Here are brought together all the
quaint enamelled eyes,
That on the green turf sucked the honeyed showers,
And purple all the ground with vernal flowers.
Bring the rathe primrose that forsaken dies,
The tufted crow-toe, and pale jessamine,
The white pink and the pansy freaked with jet,
The glowing violet,
The musk rose, and the well attired woodbine,
With cowslips wan that hang the pensive head,
And every flower that sad embroidery wears.[23]
We cannot, happily we need not try to, contrast or compare the beauty of
gardens with that of woods and fields.
And yet to the true lover of Nature wild flowers have a charm which no
garden can equal. Cultivated plants are but a living herbarium. They
surpass, no doubt, the dried specimens of a museum, but, lovely as they
are, they can be no more compared with the natural vegetation of our
woods and fields than the captives in the Zoological Gardens with the
same wild species in their native forests and mountains.
Often indeed, our woods and fields rival gardens even in the richness of
colour. We have all seen meadows white with Narcissus, glowing with
Buttercups, Cowslips, early purple Orchis, or Cuckoo Flowers; cornfields
blazing with Poppies; woods carpeted with Bluebells, Anemones,
Primroses, and Forget-me-nots; commons with the yellow Lady's Bedstraw,
Harebells, and the sweet Thyme; marshy places with the yellow stars of
the Bog Asphodel, the Sun-dew sparkling with diamonds, Ragged Robin, the
beautifully fringed petals of the Buckbean, the lovely little Bog
Pimpernel, or the feathery tufts of Cotton Grass; hedgerows with
Hawthorn and Traveller's Joy, Wild Rose and Honeysuckle, while
underneath are the curious leaves and orange fruit of the Lords and
Ladies, the snowy stars of the Stitchwort, Succory, Yarrow, and several
kinds of Violets; while all along the banks of streams are the tall red
spikes of the Loosestrife, the Hemp Agrimony, Water Groundsel, Sedges,
Bulrushes, Flowering Rush, Sweet Flag, etc.
Many other sweet names will also at once occur to us--Snowdrops,
Daffodils and Hearts-ease, Lady's Mantles and Lady's Tresses, Eyebright,
Milkwort, Foxgloves, Herb Roberts, Geraniums, and among rarer species,
at least in England, Columbines and Lilies.
But Nature does not provide delights for the eye only. The other senses
are not forgotten. A thousand sounds--many delightful in themselves, and
all by association--songs of birds, hum of insects, rustle of leaves,
ripple of water, seem to fill the air.
Flowers again are sweet, as well as lovely. The scent of pine woods,
which is said to be very healthy, is certainly delicious, and the effect
of Woodland scenery is good for the mind as well as for the body.
"Resting quietly under an ash tree, with the scent of flowers, and the
odour of green buds and leaves, a ray of sunlight yonder lighting up the
lichen and the moss on the oak trunk, a gentle air stirring in the
branches above, giving glimpses of fleecy clouds sailing in the ether,
there comes into the mind a feeling of intense joy in the simple fact of
living."[24]
The wonderful phenomenon of phosphorescence is not a special gift to the
animal kingdom. Henry O. Forbes describes a forest in Sumatra: "The stem
of every tree blinked with a pale greenish-white light which undulated
also across the surface of the ground like moonlight coming and going
behind the clouds, from a minute thread-like fungus invisible in the
day-time to the unassisted eye; and here and there thick dumpy mushrooms
displayed a sharp, clear dome of light, whose intensity never varied or
changed till the break of day; long phosphorescent caterpillars and
centipedes crawled out of every corner, leaving a trail of light behind
them, while fire-flies darted about above like a lower firmament."[25]
Woods and Forests were to our ancestors the special scenes of
enchantment.
The great Ash tree Yggdrasil bound together Heaven, Earth, and Hell. Its
top reached to Heaven, its branches covered the Earth, and the roots
penetrated into Hell. The three Normas or Fates sat under it, spinning
the thread of life.
Of all the gods and goddesses of classical mythology or our own
folk-lore, none were more fascinating than the Nature Spirits--Elves and
Fairies, Neckans and Kelpies, Pixies and Ouphes, Mermaids, Undines,
Water Spirits, and all the Elfin world
Which have their haunts in dale and piny mountain,
Or forests, by slow stream or tingling brook.
They come out, as we are told, especially on moonlight nights. But while
evening thus clothes many a scene with poetry, forests are fairy land
all day long.
Almost any wood contains many and many a spot well suited for Fairy
feasts; where one might most expect to find Titania, resting, as once we
are told,
She lay upon a bank, the favourite haunt
Of the Spring wind in its first sunshine hour,
For the luxuriant strawberry blossoms spread
Like a snow shower then, and violets
Bowed down their purple vases of perfume
About her pillow,--linked in a gay band
Floated fantastic shapes; these were her guards,
Her lithe and rainbow elves.
The fairies have disappeared, and, so far as England is concerned, the
larger forest animals have vanished almost as completely. The Elk and
Bear, the Boar and Wolf have gone, the Stag has nearly disappeared, and
but a scanty remnant of the original wild Cattle linger on at
Chillingham. Still the woods teem with life; the Fox and Badger, Stoat
and Weasel, Hare and Rabbit, and Hedgehog,
The tawny squirrel vaulting through the boughs,
Hawk, buzzard, jay, the mavis and the merle,[26]
the Owls and Nightjar, the Woodpecker, Nuthatch, Magpie, Doves, and a
hundred more.
In early spring the woods are bright with the feathery catkins of the
Willow, followed by the soft green of the Beech, the white or pink
flowers of the Thorn, the pyramids of the Horse-chestnut, festoons of
the Laburnum and Acacia, and the Oak slowly wakes from its winter sleep,
while the Ash leaves long linger in their black buds.
Under foot is a carpet of flowers--Anemones, Cowslips, Primroses,
Bluebells, and the golden blossoms of the Broom, which, however, while
Gorse and Heather continue in bloom for months, "blazes for a week or
two, and is then completely extinguished, like a fire that has burnt
itself out."[27]
In summer the tints grow darker, the birds are more numerous and full of
life; the air teems with insects, with the busy murmur of bees and the
idle hum of flies, while the cool of morning and evening, and the heat
of the day, are all alike delicious.
As the year advances and the flowers wane, we have many beautiful fruits
and berries, the red hips and haws of the wild roses, scarlet holly
berries, crimson yew cups, the translucent berries of the Guelder Rose,
hanging coral beads of the Black Bryony, feathery festoons of the
Traveller's Joy, and others less conspicuous, but still exquisite in
themselves--acorns, beech nuts, ash keys, and many more. It is really
difficult to say which are most beautiful, the tender greens of spring
or the rich tints of autumn, which glow so brightly in the sunshine.
Tropical fruits are even more striking. No one who has seen it can ever
forget a grove of orange trees in full fruit; while the more we examine
the more we find to admire; all perfectly and exquisitely finished
"usque ad ungues," perfect inside and outside, for Nature
Does in the Pomegranate close
Jewels more rare than Ormus shows.[28]
In winter the woods are comparatively bare and lifeless, even the
Brambles and Woodbine, which straggle over the tangle of underwood being
almost leafless.
Still even then they have a beauty and interest of their own; the mossy
boles of the trees; the delicate tracery of the branches which can
hardly be appreciated when they are covered with leaves; and under foot
the beds of fallen leaves; while the evergreens seem brighter than in
summer; the ruddy stems and rich green foliage of the Scotch Pines, and
the dark spires of the Firs, seeming to acquire fresh beauty.
Again in winter, though no doubt the living tenants of the woods are
much less numerous, many of our birds being then far away in the dense
African forests, on the other hand those which remain are much more
easily visible. We can follow the birds from tree to tree, and the
Squirrel from bough to bough.
It requires little imagination to regard trees as conscious beings,
indeed it is almost an effort not to do so.
"The various action of trees rooting themselves in inhospitable rocks,
stooping to look into ravines, hiding from the search of glacier winds,
reaching forth to the rays of rare sunshine, crowding down together to
drink at sweetest streams, climbing hand in hand among the difficult
slopes, opening in sudden dances among the mossy knolls, gathering into
companies at rest among the fragrant fields, gliding in grave procession
over the heavenward ridges--nothing of this can be conceived among the
unvexed and unvaried felicities of the lowland forest; while to all
these direct sources of greater beauty are added, first the power of
redundance, the mere quantity of foliage visible in the folds and on the
promontories of a single Alp being greater than that of an entire
lowland landscape (unless a view from some Cathedral tower); and to this
charm of redundance, that of clearer visibility--tree after tree being
constantly shown in successive height, one behind another, instead of
the mere tops and flanks of masses as in the plains; and the forms of
multitudes of them continually defined against the clear sky, near and
above, or against white clouds entangled among their branches, instead
of being confused in dimness of distance."[29]
There is much that is interesting in the relations of one species to
another. Many plants are parasitic upon others. The foliage of the Beech
is so thick that scarcely anything will grow under it, except those
spring plants, such as the Anemone and the Wood Buttercup or Goldilocks,
which flower early before the Beech is in leaf.
There are other cases in which the reason for the association of
species is less evident. The Larch and the Arolla (Pinus Cembra) are
close companions. They grow together in Siberia; they do not occur in
Scandinavia or Russia, but both reappear in certain Swiss valleys,
especially in the cantons of Lucerne and Valais and the Engadine.
Another very remarkable case which has recently been observed is the
relation existing between some of our forest trees and certain Fungi,
the species of which have not yet been clearly ascertained. The root
tips of the trees are as it were enclosed in a thin sheet of closely
woven mycelium. It was at first supposed that the fungus was attacking
the roots of the tree, but it is now considered that the tree and the
fungus mutually benefit one another. The fungus collects nutriment from
the soil, which passes into the tree and up to the leaves, where it is
elaborated into sap, the greater part being utilized by the tree, but a
portion reabsorbed by the fungus. There is reason to think that, in some
cases at any rate, the mycelium is that of the Truffle.
[Illustration: TROPICAL FOREST.
_To face page 179._]
The great tropical forests have a totally different character from ours.
I reproduce here the plate from Kingsley's _At Last_. The trees strike
all travellers by their magnificence, the luxuriance of their
vegetation, and their great variety. Our forests contain comparatively
few species, whereas in the tropics we are assured that it is far from
common to see two of the same species near one another. But while in our
forests the species are few, each tree has an independence and
individuality of its own. In the tropics, on the contrary, they are
interlaced and interwoven, so as to form one mass of vegetation; many of
the trunks are almost concealed by an undergrowth of verdure, and
intertwined by spiral stems of parasitic plants; from tree to tree hang
an inextricable network of lianas, and it is often difficult to tell to
which tree the fruits, flowers, and leaves really belong. The trunks run
straight up to a great height without a branch, and then form a thick
leafy canopy far overhead; a canopy so dense that even the blaze of the
cloudless blue sky is subdued, one might almost say into a weird gloom,
the effect of which is enhanced by the solemn silence. At first such a
forest gives the impression of being more open than an English wood, but
a few steps are sufficient to correct this error. There is a thick
undergrowth matted together by wiry creepers, and the intermediate space
is traversed in all directions by lines and cords.
The English traveller misses sadly the sweet songs of our birds, which
are replaced by the hoarse chatter of parrots. Now and then a succession
of cries even harsher and more discordant tell of a troop of monkeys
passing across from tree to tree among the higher branches, or lower
sounds indicate to a practised ear the neighbourhood of an ape, a sloth,
or some other of the few mammals which inhabit the great forests.
Occasionally a large blue bee hums past, a brilliant butterfly flashes
across the path, or a humming-bird hangs in the air over a flower like,
as St. Pierre says, an emerald set in coral, but "how weak it is to say
that that exquisite little being, whirring and fluttering in the air,
has a head of ruby, a throat of emerald, and wings of sapphire, as if
any triumph of the jeweller's art could ever vie with that sparkling
epitome of life and light."[30]
Sir Wyville Thomson graphically describes a morning in a Brazilian
forest:--
"The night was almost absolutely silent, only now and then a peculiarly
shrill cry of some night bird reached us from the woods. As we got into
the skirt of the forest the morning broke, but the _réveil_ in a
Brazilian forest is wonderfully different from the slow creeping on of
the dawn of a summer morning at home, to the music of the thrushes
answering one another's full rich notes from neighbouring thorn-trees.
Suddenly a yellow light spreads upwards in the east, the stars quickly
fade, and the dark fringes of the forest and the tall palms show out
black against the yellow sky, and almost before one has time to observe
the change the sun has risen straight and fierce, and the whole
landscape is bathed in the full light of day. But the morning is yet for
another hour cool and fresh, and the scene is indescribably beautiful.
The woods, so absolutely silent and still before, break at once into
noise and movement. Flocks of toucans flutter and scream on the tops of
the highest forest trees hopelessly out of shot, the ear is pierced by
the strange wild screeches of a little band of macaws which fly past you
like the wrapped-up ghosts of the birds on some gaudy old brocade."[31]
Mr. Darwin tells us that nothing can be better than the description of
tropical forests given by Bates.
"The leafy crowns of the trees, scarcely two of which could be seen
together of the same kind, were now far away above us, in another world
as it were. We could only see at times, where there was a break above,
the tracery of the foliage against the clear blue sky. Sometimes the
leaves were palmate, or of the shape of large outstretched hands; at
others finely cut or feathery like the leaves of Mimosæ. Below, the tree
trunks were everywhere linked together by sipos; the woody flexible
stems of climbing and creeping trees, whose foliage is far away above,
mingled with that of the taller independent trees. Some were twisted in
strands like cables, others had thick stems contorted in every variety
of shape, entwining snake-like round the tree trunks or forming gigantic
loops and coils among the larger branches; others, again, were of zigzag
shape, or indented like the steps of a staircase, sweeping from the
ground to a giddy height."
The reckless and wanton destruction of forests has ruined some of the
richest countries on earth. Syria and Asia Minor, Palestine and the
north of Africa were once far more populous than they are at present.
They were once lands "flowing with milk and honey," according to the
picturesque language of the Bible, but are now in many places reduced to
dust and ashes. Why is there this melancholy change? Why have deserts
replaced cities? It is mainly owing to the ruthless destruction of the
trees, which has involved that of nations. Even nearer home a similar
process may be witnessed. Two French departments--the Hautes- and
Basses-Alpes--are being gradually reduced to ruin by the destruction of
the forests. Cultivation is diminishing, vineyards are being washed
away, the towns are threatened, the population is dwindling, and unless
something is done the country will be reduced to a desert; until, when
it has been released from the destructive presence of man, Nature
reproduces a covering of vegetable soil, restores the vegetation,
creates the forests anew, and once again fits these regions for the
habitation of man.
In another part of France we have an illustration of the opposite
process.
The region of the Landes, which fifty years ago was one of the poorest
and most miserable in France, has now been made one of the most
prosperous owing to the planting of Pines. The increased value is
estimated at no less than 1,000,000,000 francs. Where there were fifty
years ago only a few thousand poor and unhealthy shepherds whose flocks
pastured on the scanty herbage, there are now sawmills, charcoal kilns,
and turpentine works, interspersed with thriving villages and fertile
agricultural lands.
In our own country, though woodlands are perhaps on the increase, true
forest scenery is gradually disappearing. This is, I suppose,
unavoidable, but it is a matter of regret. Forests have so many charms
of their own. They give a delightful impression of space and of
abundance.
The extravagance is sublime. Trees, as Jefferies says, "throw away
handfuls of flower; and in the meadows the careless, spendthrift ways of
grass and flower and all things are not to be expressed. Seeds by the
hundred million float with absolute indifference on the air. The oak has
a hundred thousand more leaves than necessary, and never hides a single
acorn. Nothing utilitarian--everything on a scale of splendid waste.
Such noble, broadcast, open-armed waste is delicious to behold. Never
was there such a lying proverb as 'Enough is as good as a feast.' Give
me the feast; give me squandered millions of seeds, luxurious carpets of
petals, green mountains of oak-leaves. The greater the waste the greater
the enjoyment--the nearer the approach to real life."
It is of course impossible here to give any idea of the complexity of
structure of our forest trees. A slice across the stem of a tree shows
many different tissues with more or less technical names, bark and
cambium, medullary rays, pith, and more or less specialised tissue;
air-vessels, punctate vessels, woody fibres, liber fibres, scalariform
vessels, and other more or less specialised tissues.
Let us take a single leaf. The name is synonymous with anything very
thin, so that we might well fancy that a leaf would consist of only one
or two layers of cells. Far from it, the leaf is a highly complex
structure. On the upper surface are a certain number of scattered hairs,
while in the bud these are often numerous, long, silky, and serve to
protect the young leaf, but the greater number fall off soon after the
leaf expands. The hairs are seated on a layer of flattened cells--the
skin or epidermis. Below this are one or more layers of "palisade
cells," the function of which seems to be to regulate the quantity of
light entering the leaf. Under these again is the "parenchyme," several
layers of more or less rounded cells, leaving air spaces and passages
between them. From place to place in the parenchyme run "fibro-vascular
bundles," forming a sort of skeleton to the leaf, and comprising
air-vessels on the upper side, rayed or dotted vessels with woody fibre
below, and vessels of various kinds. The under surface of the leaf is
formed by another layer of flattened cells, supporting generally more or
less hairs, and some of them specially modified so as to leave minute
openings or "stomata" leading into the air passages. These stomata are
so small that there are millions on a single leaf, and on plants growing
in dry countries, such as the Evergreen Oak, Oleander, etc., they are
sunk in pits, and further protected by tufts of hair.
The cells of the leaf again are themselves complex. They consist of a
cell wall perforated by extremely minute orifices, of protoplasm, cell
fluid, and numerous granules of "Chlorophyll," which give the leaf its
green colour.
While these are, stated very briefly, the essential parts of a leaf, the
details differ in every species, while in the same species and even in
the same plant, the leaves present minor differences according to the
situation in which they grow.
Since, then, there is so much complex structure in a single leaf, what
must it be in a whole plant? There is a giant sea-weed (Macrocystis),
which has been known to reach a length of 1000 feet, as also do some of
the lianas of tropical forests. These, however, attain no great bulk,
and the most gigantic specimens of the vegetable kingdom yet known are
the Wellingtonia (Sequoia) gigantea, which grows to a height of 450
feet, and the Blue Gum (Eucalyptus) even to 480.
One is apt to look on animal structure as more delicate, and of a higher
order, than that of plants. And so no doubt it is. Yet an animal, even
man himself, will recover from a wound or an operation more rapidly and
more perfectly than a tree.[32]
Trees again derive a special interest from the venerable age they
attain. In some cases, no doubt, the age is more or less mythical, as,
for instance, the Olive of Minerva at Athens, the Oaks mentioned by
Pliny, "which were thought coeval with the world itself," the Fig tree,
"under which the wolf suckled the founder of Rome and his brother,
lasting (as Tacitus calculated) 840 years, putting out new shoots, and
presaging the translation of that empire from the Cæsarian line,
happening in Nero's reign."[33] But in other cases the estimates rest on
a surer foundation, and it cannot be doubted that there are trees still
living which were already of considerable size at the time of the
Conquest. The Soma Cypress of Lombardy, which is 120 feet high and 23 in
circumference, is calculated to go back to forty years before the birth
of Christ. Francis the First is said to have driven his sword into it in
despair after the battle of Padua, and Napoleon altered his road over
the Simplon so as to spare it.
Ferdinand and Isabella in 1476 swore to maintain the privileges of the
Biscayans under the old Oak of Guernica. In the Ardennes an Oak cut down
in 1824 contained a funeral urn and some Samnite coins. A writer at the
time drew the conclusion that it must have been already a large tree
when Rome was founded, and though the facts do not warrant this
conclusion, the tree did, no doubt, go back to Pagan times. The great
Yew of Fountains Abbey is said to have sheltered the monks when the
abbey was rebuilt in 1133, and is estimated at an age of 1300 years;
that at Brabourne in Kent at 3000. De Candolle gives the following as
the ages attainable:--
The Ivy 450 years
Larch 570 "
Plane 750 "
Cedar of Lebanon 800 "
Lime 1100 "
Oak 1500 "
Taxodium distichum 4000 to 6000
Baobab 6000 years
Nowhere is woodland scenery more beautiful than where it passes
gradually into the open country. The separate trees, having more room
both for their roots and branches, are finer, and can be better seen,
while, when they are close together, "one cannot see the wood for the
trees." The vistas which open out are full of mystery and of promise,
and tempt us gradually out into the green fields.
What pleasant memories these very words recall, games in the hay as
children, and sunny summer days throughout life.
"Consider," says Ruskin,[34] "what we owe to the meadow grass, to the
covering of the dark ground by that glorious enamel, by the companies of
those soft countless and peaceful spears. The fields! Follow but forth
for a little time the thought of all that we ought to recognise in those
words. All spring and summer is in them--the walks by silent scented
paths, the rests in noonday heat, the joy of herds and flocks, the power
of all shepherd life and meditation, the life of sunlight upon the
world, falling in emerald streaks, and soft blue shadows, where else it
would have struck on the dark mould or scorching dust, pastures beside
the pacing brooks, soft banks and knolls of lowly hills, thymy slopes of
down overlooked by the blue line of lifted sea, crisp lawns all dim with
early dew, or smooth in evening warmth of barred sunshine, dinted by
happy feet, and softening in their fall the sound of loving voices.
* * * * *
"Go out, in the spring time, among the meadows that slope from the
shores of the Swiss lakes to the roots of their lower mountains. There,
mingled with the taller gentians and the white narcissus, the grass
grows deep and free, and as you follow the winding mountain paths,
beneath arching boughs all veiled and dim with blossom,--paths, that for
ever droop and rise over the green banks and mounds sweeping down in
scented undulation, steep to the blue water, studded here and there with
new mown heaps, filling all the air with fainter sweetness,--look up
towards the higher hills, where the waves of everlasting green roll
silently into their long inlets among the shadows of the pines; and we
may, perhaps, at last know the meaning of those quiet words of the 147th
Psalm, 'He maketh the grass to grow upon the mountains.'"
"On fine days," he tells us again in his _Autobiography_, "when the
grass was dry, I used to lie down on it, and draw the blades as they
grew, with the ground herbage of buttercup or hawkweed mixed among them,
until every square foot of meadow, or mossy bank, became an infinite
picture and possession to me, and the grace and adjustment to each other
of growing leaves, a subject of more curious interest to me than the
composition of any painter's masterpieces."
In the passage above quoted, Ruskin alludes especially to Swiss meadows.
They are especially remarkable in the beauty and variety of flowers. In
our fields the herbage is mainly grass, and if it often happens that
they glow with Buttercups or are white with Ox-eye-daisies, these are
but unwelcome intruders and add nothing to the value of the hay. Swiss
meadows, on the contrary, are sweet and lovely with wild Geraniums,
Harebells, Bluebells, Pink Restharrow, Yellow Lady's Bedstraw, Chervil,
Eyebright, Red and White Silenes, Geraniums, Gentians, and many other
flowers which have no familiar English names; all adding not only to the
beauty and sweetness of the meadows, but forming a valuable part of the
crop itself.[35] On the other hand "turf" is peculiarly English, and no
turf is more delightful than that of our Downs--delightful to ride on,
to sit on, or to walk on. The turf indeed feels so springy under our
feet that walking on it seems scarcely an exertion: one could almost
fancy that the Downs themselves were still rising, even higher, into the
air.
The herbage of the Downs is close rather than short, hillocks of sweet
thyme, tufts of golden Potentilla, of Milkwort--blue, pink, and
white--of sweet grass and Harebells: here and there pink with Heather,
or golden with Furze or Broom, while over all are the fresh air and
sunshine, sweet scents, and the hum of bees. And if the Downs seem full
of life and sunshine, their broad shoulders are types of kindly
strength, they give also an impression of power and antiquity, while
every now and then we come across a tumulus, or a group of great grey
stones, the burial place of some ancient hero, or a sacred temple of our
pagan forefathers.
On the Downs indeed things change slowly, and in parts of Sussex the
strong slow oxen still draw the waggons laden with warm hay or golden
wheat sheaves, or drag the wooden plough along the slopes of the Downs,
just as they did a thousand years ago.
I love the open Down most, but without hedges England would not be
England. Hedges are everywhere full of beauty and interest, and nowhere
more so than at the foot of the Downs, when they are in great part
composed of wild Guelder Roses and rich dark Yews, decked with festoons
of Traveller's Joy, the wild Bryonies, and garlands of Wild Roses
covered with thousands of white or delicate pink flowers, each with a
centre of gold.
At the foot of the Downs spring clear sparkling streams; rain from
heaven purified still further by being filtered through a thousand feet
of chalk; fringed with purple Loosestrife and Willowherb, starred with
white Water Ranunculuses, or rich Watercress, while every now and then a
brown water rat rustles in the grasses at the edge, and splashes into
the water, or a pink speckled trout glides out of sight.
In many of our midland and northern counties most of the meadows lie in
parallel undulations or "rigs." These are generally about a furlong (220
yards) in length, and either one or two poles (5-1/2 or 11 yards) in
breadth. They seldom run straight, but tend to curve towards the left.
At each end of the field a high bank, locally called a balk, often 3 or
4 feet high, runs at right angles to the rigs. In small fields there are
generally eight, but sometimes ten, of these rigs, which make in the one
case 4, in the other 5 acres. These curious characters carry us back to
the old tenures, and archaic cultivation of land, and to a period when
the fields were not in pasture, but were arable.
They also explain our curious system of land measurement. The "acre" is
the amount which a team of oxen were supposed to plough in a day. It
corresponds to the German "morgen" and the French "journée." The furlong
or long "furrow" is the distance which a team of oxen can plough
conveniently without stopping to rest. Oxen, as we know, were driven
not with a whip, but with a goad or pole, the most convenient length for
which was 16-1/2 feet, and the ancient ploughman used his "pole" or
"perch" by placing it at right angles to his first furrow, thus
measuring the amount he had to plough. Hence our "pole" or "perch" of
16-1/2 feet, which at first sight seems a very singular unit to have
selected. This width is also convenient both for turning the plough, and
also for sowing. Hence the most convenient unit of land for arable
purposes was a furlong in length and a perch or pole in width.
The team generally consisted of eight oxen. Few peasants, however,
possessed a whole team, several generally joining together, and dividing
the produce. Hence the number of "rigs," one for each ox. We often,
however, find ten instead of eight; one being for the parson's tithe,
the other tenth going to the ploughman.
When eight oxen were employed the goad would not of course reach the
leaders, which were guided by a man who walked on the near side. On
arriving at the end of each furrow he turned them round, and as it was
easier to pull than to push them, this gradually gave the furrow a turn
towards the left, thus accounting for the slight curvature. Lastly,
while the oxen rested on arriving at the end of the furrow, the
ploughmen scraped off the earth which had accumulated on the coulter and
ploughshare, and the accumulation of these scrapings gradually formed
the balk.
It is fascinating thus to trace indications of old customs and modes of
life, but it would carry us away from the present subject.
Even though the Swiss meadows may offer a greater variety, our English
fields are yet rich in flowers: yellow with Cowslips and Primroses, pink
with Cuckoo flowers and purple with Orchis, while, however, unwelcome to
the eye of the farmer,
the rich Buttercup
Its tiny polished urn holds up,
Filled with ripe summer to the edge,[36]
turning many a meadow into a veritable field of the cloth of gold, and
there are few prettier sights in nature than an English hay field on a
summer evening, with a copse perhaps at one side and a brook on the
other; men with forks tossing the hay in the air to dry; women with
wooden rakes arranging it in swathes ready for the great four-horse
waggon, or collecting it in cocks for the night; while some way off the
mowers are still at work, and we hear from time to time the pleasant
sound of the whetting of the scythe. All are working with a will lest
rain should come and their labour be thrown away. This too often
happens. But though we often complain of our English climate, it is yet,
take it all in all, one of the best in the world, being comparatively
free from extremes either of heat or cold, drought or deluge. To the
happy mixture of sunshine and of rain we owe the greenness of our
fields,
sparkling with dewdrops
Indwelt with little angels of the Sun,[37]
lit and
warmed by golden sunshine
And fed by silver rain,
which now and again sprinkles the whole earth with diamonds.
FOOTNOTES:
[22] _The Spectator._
[23] Milton.
[24] Jefferies.
[25] Forbes, _A Naturalist's Wanderings in the Eastern Archipelago_.
[26] Tennyson.
[27] Hamerton.
[28] Marvell.
[29] Ruskin.
[30] Thomson, _Voyage of the Challenger_.
[31] Thomson, _Voyage of the Challenger_.
[32] Sir J. Paget, _On the Pathology of Plants_.
[33] Evelyn's _Sylva_.
[34] _Modern Painters._
[35] M. Correvon informs me that the Gruyère cheese is supposed to owe
its peculiar flavour to the alpine Alchemilla, which is now on that
account often purposely sown elsewhere.
[36] J. R. Lowell.
[37] Hamerton.
CHAPTER VI
MOUNTAINS
Mountains "seem to have been built for the human race, as at
once their schools and cathedrals; full of treasures of
illuminated manuscript for the scholar, kindly in simple
lessons for the worker, quiet in pale cloisters for the
thinker, glorious in holiness for the worshipper. They are
great cathedrals of the earth, with their gates of rock,
pavements of cloud, choirs of stream and stone, altars of snow,
and vaults of purple traversed by the continual
stars."--RUSKIN.
[Illustration: SUMMIT OF MONT BLANC. _To face page 203._]
CHAPTER VI
MOUNTAINS
The Alps are to many of us an inexhaustible source of joy and peace, of
health, and even of life. We have gone to them jaded and worn, feeling,
perhaps without any external cause, anxious and out of spirits, and have
returned full of health, strength, and energy. Among the mountains
Nature herself seems freer and happier, brighter and purer, than
elsewhere. The rush of the rivers, and the repose of the lakes, the pure
snowfields and majestic glaciers, the fresh air, the mysterious summits
of the mountains, the blue haze of the distance, the morning tints and
the evening glow, the beauty of the sky and the grandeur of the storm,
have all refreshed and delighted us time after time, and their memories
can never fade away.
Even now as I write comes back to me the bright vision of an Alpine
valley--blue sky above, glittering snow, bare grey or rich red rock,
dark pines here and there, mixed with bright green larches, then patches
of smooth alp, with clumps of birch and beech, and dotted with brown
châlets; then below them rock again, and wood, but this time with more
deciduous trees; and then the valley itself, with emerald meadows,
interspersed with alder copses, threaded together by a silver stream;
and I almost fancy I can hear the tinkling of distant cowbells coming
down from the alp, and the delicious murmur of the rushing water. The
endless variety, the sense of repose and yet of power, the dignity of
age, the energy of youth, the play of colour, the beauty of form, the
mystery of their origin, all combine to invest mountains with a solemn
beauty.
I feel with Ruskin that "mountains are the beginning and the end of all
natural scenery; in them, and in the forms of inferior landscape that
lead to them, my affections are wholly bound up; and though I can look
with happy admiration at the lowland flowers, and woods, and open
skies, the happiness is tranquil and cold, like that of examining
detached flowers in a conservatory, or reading a pleasant book." And of
all mountain views which he has seen, the finest he considers is that
from the Montanvert: "I have climbed much and wandered much in the heart
of the high Alps, but I have never yet seen anything which equalled the
view from the cabin of the Montanvert."
It is no mere fancy that among mountains the flowers are peculiarly
large and brilliant in colour. Not only are there many beautiful species
which are peculiar to mountains,--alpine Gentians, yellow, blue, and
purple; alpine Rhododendrons, alpine Primroses and Cowslips, alpine
Lychnis, Columbine, Monkshood, Anemones, Narcissus, Campanulas,
Soldanellas, and a thousand others less familiar to us,--but it is well
established that even within the limits of the same species those living
up in the mountains have larger and brighter flowers than their sisters
elsewhere.
Various alpine species belonging to quite distinct families form close
moss-like cushions, gemmed with star-like flowers, or covered
completely with a carpet of blossom. On the lower mountain slopes and in
alpine valleys trees seem to flourish with peculiar luxuriance. Pines
and Firs and Larches above; then, as we descend, Beeches and magnificent
Chestnuts, which seem to rejoice in the sweet, fresh air and the pure
mountain streams.
To any one accustomed to the rich bird life of English woods and
hedgerows, it must be admitted that Swiss woods and Alps seem rather
lonely and deserted. Still the Hawk, or even Eagle, soaring high up in
the air, the weird cry of the Marmot, and the knowledge that, even if
one cannot see Chamois, they may all the time be looking down on us,
give the Alps, from this point of view also, a special interest of their
own.
Another great charm of mountain districts is the richness of colour.
"Consider,[38] first, the difference produced in the whole tone of
landscape colour by the introductions of purple, violet, and deep
ultra-marine blue which we owe to mountains. In an ordinary lowland
landscape we have the blue of the sky; the green of the grass, which I
will suppose (and this is an unnecessary concession to the lowlands)
entirely fresh and bright; the green of trees; and certain elements of
purple, far more rich and beautiful than we generally should think, in
their bark and shadows (bare hedges and thickets, or tops of trees, in
subdued afternoon sunshine, are nearly perfect purple and of an
exquisite tone), as well as in ploughed fields, and dark ground in
general. But among mountains, in addition to all this, large unbroken
spaces of pure violet and purple are introduced in their distances; and
even near, by films of cloud passing over the darkness of ravines or
forests, blues are produced of the most subtle tenderness; these azures
and purples passing into rose colour of otherwise wholly unattainable
delicacy among the upper summits, the blue of the sky being at the same
time purer and deeper than in the plains. Nay, in some sense, a person
who has never seen the rose colour of the rays of dawn crossing a blue
mountain twelve or fifteen miles away can hardly be said to know what
tenderness in colour means at all; bright tenderness he may, indeed,
see in the sky or in a flower, but this grave tenderness of the far-away
hill-purples he cannot conceive."
"I do not know," he says elsewhere, "any district possessing a more pure
or uninterrupted fulness of mountain character (and that of the highest
order), or which appears to have been less disturbed by foreign
agencies, than that which borders the course of the Trient between
Valorsine and Martigny. The paths which lead to it, out of the valley of
the Rhone, rising at first in steep circles among the walnut trees, like
winding stairs among the pillars of a Gothic tower, retire over the
shoulders of the hills into a valley almost unknown, but thickly
inhabited by an industrious and patient population. Along the ridges of
the rocks, smoothed by old glaciers, into long, dark, billowy swellings,
like the backs of plunging dolphins, the peasant watches the slow
colouring of the tufts of moss and roots of herb, which, little by
little, gather a feeble soil over the iron substance; then, supporting
the narrow strip of clinging ground with a few stones, he subdues it to
the spade, and in a year or two a little crest of corn is seen waving
upon the rocky casque."
Tyndall, speaking of the scene from the summit of the Little
Scheideck,[39] says: "The upper air exhibited a commotion which we did
not experience; clouds were wildly driven against the flanks of the
Eiger, the Jungfrau thundered behind, while in front of us a magnificent
rainbow, fixing one of its arms in the valley of Grindelwald, and,
throwing the other right over the crown of the Wetterhorn, clasped the
mountain in its embrace. Through jagged apertures in the clouds floods
of golden light were poured down the sides of the mountain. On the
slopes were innumerable châlets, glistening in the sunbeams, herds
browsing peacefully and shaking their mellow bells; while the blackness
of the pine trees, crowded into woods, or scattered in pleasant clusters
over alp and valley, contrasted forcibly with the lively green of the
fields."
Few men had more experience of mountains than Mr. Whymper, and from him,
I will quote one remarkable passage describing the view from the summit
of the Matterhorn just before the terrible catastrophe which overshadows
the memory of his first ascent.
"The day was one of those superlatively calm and clear ones which
usually precede bad weather. The atmosphere was perfectly still and free
from all clouds or vapours. Mountains fifty, nay, a hundred miles off
looked sharp and near. All their details--ridge and crag, snow and
glacier--stood out with faultless definition. Pleasant thoughts of happy
days in bygone years came up unbidden as we recognised the old familiar
forms. All were revealed, not one of the principal peaks of the Alps was
hidden. I see them clearly now, the great inner circle of giants, backed
by the ranges, chains, and _massifs_.... Ten thousand feet beneath us
were the green fields of Zermatt, dotted with châlets, from which blue
smoke rose lazily. Eight thousand feet below, on the other side, were
the pastures of Breuil. There were black and gloomy forests; bright and
cheerful meadows, bounding waterfalls and tranquil lakes, fertile lands
and savage wastes, sunny plains and frigid plateaux. There were the most
rugged forms and the most graceful outlines, bold perpendicular cliffs
and gentle undulating slopes; rocky mountains and snowy mountains,
sombre and solemn, or glittering and white, with walls, turrets,
pinnacles, pyramids, domes, cones, and spires! There was every
combination that the world can give, and every contrast that the heart
could desire."
These were summer scenes, but the Autumn and Winter again have a
grandeur and beauty of their own.
"Autumn is dark on the mountains; grey mist rests on the hills. The
whirlwind is heard on the heath. Dark rolls the river through the narrow
plain. The leaves twirl round with the wind, and strew the grave of the
dead."[40]
Even bad weather often but enhances the beauty and grandeur of
mountains. When the lower parts are hidden, and the peaks stand out
above the clouds, they look much loftier than if the whole mountain
side is visible. The gloom lends a weirdness and mystery to the scene,
while the flying clouds give it additional variety.
Rain, moreover, adds vividness to the colouring. The leaves and grass
become a brighter green, "every sunburnt rock glows into an agate," and
when fine weather returns the new snow gives intense brilliance, and
invests the woods especially with the beauty of Fairyland. How often in
alpine districts does one long "for the wings of a dove," more
thoroughly to enjoy and more completely to explore, the mysteries and
recesses of the mountains. The mind, however, can go, even if the body
must remain behind.
Each hour of the day has a beauty of its own. The mornings and evenings
again glow with different and even richer tints.
In mountain districts the cloud effects are brighter and more varied
than in flatter regions. The morning and evening tints are seen to the
greatest advantage, and clouds floating high in the heavens sometimes
glitter with the most exquisite iridescent hues
that blush and glow
Like angels' wings.[41]
On low ground one may be in the clouds, but not above them. But as we
look down from mountains and see the clouds floating far below us, we
almost seem as if we were looking down on earth from one of the heavenly
bodies.
Not even in the Alps is there anything more beautiful than the "after
glow" which lights up the snow and ice with a rosy tint for some time
after the sun has set. Long after the lower slopes are already in the
shade, the summit of Mont Blanc for instance is transfigured by the
light of the setting sun glowing on the snow. It seems almost like a
light from another world, and vanishes as suddenly and mysteriously as
it came.
As we look up from the valleys the mountain peaks seem like separate
pinnacles projecting far above the general level. This, however, is a
very erroneous impression, and when we examine the view from the top of
any of the higher mountains, or even from one of very moderate
elevation, if well placed, such say as the well-known Piz Languard, we
see that in many cases they must have once formed a dome, or even a
table land, out of which the valleys have been carved. Many mountain
chains were originally at least twice as high as they are now, and the
highest peaks are those which have suffered least from the wear and tear
of time.
We used to speak of the everlasting hills, and are only beginning to
realise the vast and many changes which our earth has undergone.
There rolls the deep where grew the tree.
O earth, what changes hast thou seen!
There where the long street roars, hath been
The stillness of the central sea.
The hills are shadows, and they flow
From form to form, and nothing stands;
They melt like mist, the solid lands,
Like clouds they shape themselves and go.[42]
THE ORIGIN OF MOUNTAINS
Geography moreover acquires a new interest when we once realise that
mountains are no mere accidents, but that for every mountain chain, for
every peak and valley, there is a cause and an explanation.
The origin of Mountains is a question of much interest. The building up
of Volcanoes is even now going on before our eyes. Some others, the
Dolomites for instance, have been regarded by Richthofen and other
geologists as ancient coral islands. The long lines of escarpment which
often stretch for miles across country, are now ascertained, mainly
through the researches of Whitaker, to be due to the differential action
of aerial causes. The general origin of mountain chains, however, was at
first naturally enough attributed to direct upward pressure from below.
To attribute them in any way to subsidence seems almost a paradox, and
yet it appears to be now well established that the general cause is
lateral compression, due to contraction of the underlying mass. The
earth, we know, has been gradually cooling, and as it contracted in
doing so, the strata of the crust would necessarily be thrown into
folds. When an apple dries and shrivels in winter, the surface becomes
covered with ridges. Or again, if we place some sheets of paper between
two weights on a table, and then bring the weights nearer together, the
paper will be crumpled up.
[Illustration: Fig. 17.--Adapted from Ball's paper "On the Formation of
Alpine Valleys and Lakes," _Lond. and Ed. Phil. Mag._ 1863, p. 96.]
In the same way let us take a section of the earth's surface AB (Fig.
17), and suppose that, by the gradual cooling and consequent contraction
of the mass, AB sinks to A'B', then to A''B'', and finally to A'''B'''.
Of course if the cooling of the surface and of the deeper portion were
the same, then the strata between A and B would themselves contract, and
might consequently still form a regular curve between A''' and B'''. As
a matter of fact, however, the strata at the surface of our globe have
long since approached a constant temperature. Under these circumstances
there would be no contraction of the strata between A and B
corresponding to that of those in the interior, and consequently they
could not lie flat between A''' and B''', but must be thrown into folds,
commencing along any line of least resistance. Sometimes indeed the
strata are completely inverted, as in Fig. 19, and in other cases they
have been squeezed for miles out of their original position. This
explanation was first, I believe, suggested by Steno. It has been
recently developed by Ball and Suess, and especially by Heim. In this
manner it is probable that most mountain chains originated.[43]
The structure of mountain districts confirms this theoretical
explanation. It is obvious of course that when strata are thrown into
folds, they will, if strained too much, give way at the summit of the
fold. Before doing so, however, they are stretched and consequently
loosened, while on the other hand the strata at the bottom of the fold
are compressed: the former, therefore, are rendered more susceptible of
disintegration, the latter on the contrary acquire greater powers of
resistance. Hence denudation will act with more effect on the upper
than on the lower portion of the folds, and if continued long enough, so
that, as shown in the above diagram, the dotted portion is removed, we
find the original hill tops replaced by valleys, and the original
valleys forming the hill tops. Every visitor to Switzerland must have
noticed hills where the strata lie as shown in parts of Fig. 18, and
where it is obvious that strata corresponding to those in dots must have
been originally present.
In the Jura, for instance, a glance at any good map of the district will
show a succession of ridges running parallel to one another in a
slightly curved line from S.W. to N.E. That these ridges are due to
folds of the earth's surface is clear from the following figure in
Jaccard's work on the Geology of the Jura, showing a section from
Brenets due south to Neuchâtel by Le Locle. These folds are
comparatively slight and the hills of no great height. Further south,
however, the strata are much more violently dislocated and compressed
together. The Mont Salève is the remnant of one of these ridges.
[Illustration: Fig. 18.--Section across the Jura from Brenets to
Neuchâtel.]
In the Alps the contortions are much greater than in the Jura. Fig. 19
shows a section after Heim, from the Spitzen across the Brunnialp, and
the Maderanerthal. It is obvious that the valleys are due mainly to
erosion, that the Maderaner valley has been cut out of the crystalline
rocks _s_, and was once covered by the Jurassic strata _j_, which must
have formerly passed in a great arch over what is now the valley.
However improbable it may seem that so great an amount of rock should
have disappeared, evidence is conclusive. Ramsay has shown that in some
parts of Wales not less than 29,000 feet have been removed, while there
is strong reason for the belief that in Switzerland an amount has been
carried away equal to the present height of the mountains; though of
course it does not follow that the Alps were once twice as high as they
are at present, because elevation and erosion must have gone on
contemporaneously.
[Illustration: Fig. 19.--_e_, Eocene strata; _j_, Jurassic; _s_,
Crystalline rocks.]
It has been calculated that the strata between Bâle and the St. Gotthard
have been compressed from 202 miles to 130 miles, the Ardennes from 50
to 25 miles, and the Appalachians from 153 miles to 65! Prof. Gumbel has
recently expressed the opinion that the main force to which the
elevation of the Alps was due acted along the main axis of elevation.
Exactly the opposite inference would seem really to follow from the
facts. If the centre of force were along the axis of elevation, the
result would, as Suess and Heim have pointed out, be to extend, not to
compress, the strata; and the folds would remain quite unaccounted for.
The suggestion of compression is on the contrary consistent with the
main features of Swiss geography. The principal axis follows a curved
line from the Maritime Alps towards the north-east by Mont Blanc and
Monte Rosa and St. Gotthard to the mountains overlooking the Engadine.
The geological strata follow the same direction. North of a line running
through Chambery, Yverdun, Neuchâtel, Solothurn, and Olten to Waldshut
on the Rhine are Jurassic strata; between that line and a second nearly
parallel and running through Annecy, Vevey, Lucerne, Wesen, Appenzell,
and Bregenz on the Lake of Constance, is the lowland occupied by later
Tertiary strata; between this second line and another passing through
Albertville, St. Maurice, Lenk, Meiringen, and Altdorf lies a more or
less broken band of older Tertiary strata; south of which are a
Cretaceous zone, one of Jurassic age, then a band of crystalline rocks,
while the central core, so to say, of the Alps, as for instance at St.
Gotthard, consists mainly of gneiss or granite. The sedimentary deposits
reappear south of the Alps, and in the opinion of some high authorities,
as, for instance, of Bonney and Heim, passed continuously over the
intervening regions. The last great upheaval commenced after the Miocene
period, and continued through the Pliocene. Miocene strata attain in the
Righi a height of 6000 feet.
For neither the hills nor the mountains are everlasting, or of the same
age.
The Welsh mountains are older than the Vosges, the Vosges than the
Pyrenees, the Pyrenees than the Alps, and the Alps than the Andes, which
indeed are still rising; so that if our English mountains are less
imposing so far as mere height is concerned, they are most venerable
from their great antiquity.
But though the existing Alps are in one sense, and speaking
geologically, very recent, there is strong reason for believing that
there was a chain of lofty mountains there long previously. "The first
indication," says Judd, "of the existence of a line of weakness in this
portion of the earth's crust is found towards the close of the Permian
period, when a series of volcanic outbursts on the very grandest scale
took place" along a line nearly following that of the present Alps, and
led to the formation of a range of mountains, which, in his opinion,
must have been at least 8000 to 9000 feet high. Ramsay and Bonney have
also given strong reasons for believing that the present line of the
Alps was, at a still earlier period, occupied by a range of mountains no
less lofty than those of to-day. Thus then, though the present Alps are
comparatively speaking so recent, there are good grounds for the belief
that they were preceded by one or more earlier ranges, once as lofty as
they are now, but which were more or less completely levelled by the
action of air and water, just as is happening now to the present
mountain ranges.
Movements of elevation and subsidence are still going on in various
parts of the world. Scandinavia is rising in the north, and sinking at
the south. South America is rising on the west and sinking in the east,
rotating in fact on its axis, like some stupendous pendulum.
The crushing and folding of the strata to which mountain chains are due,
and of which the Alps afford such marvellous illustrations, necessarily
give rise to Earthquakes, and the slight shocks so frequent in parts of
Switzerland[44] appear to indicate that the forces which have raised the
Alps are not yet entirely spent, and that slow subterranean movements
are still in progress along the flanks of the mountains.
But if the mountain chains are due to compression, the present valleys
are mainly the result of denudation. As soon as a mountain range is once
raised, all nature seems to conspire against it. Sun and Frost, Heat
and Cold, Air and Water, Ice and Snow, every plant, from the Lichen to
the Oak, and every animal, from the Worm to Man himself, combine to
attack it. Water, however, is the most powerful agent of all. The autumn
rains saturate every pore and cranny; the water as it freezes cracks and
splits the hardest rocks; while the spring sun melts the snow and swells
the rivers, which in their turn carry off the debris to the plains.
Perhaps, however, it would after all be more correct to say that Nature,
like some great artist, carves the shapeless block into form, and endows
the rude mass with life and beauty.
"What more," said Hutton long ago, "is required to explain the
configuration of our mountains and valleys? Nothing but time. It is not
any part of the process that will be disputed; but, after allowing all
the parts, the whole will be denied; and for what? Only because we are
not disposed to allow that quantity of time which the absolution of so
much wasted mountain might require."
The tops of the Swiss mountains stand, and since their elevation have
probably always stood, above the range of ice, and hence their bold
peaks. In Scotland, on the contrary, and still more in Norway, the sheet
of ice which once, as is the case with Greenland now, spread over the
whole country, has shorn off the summits and reduced them almost to
gigantic bosses; while in Wales the same causes, together with the
resistless action of time--for, as already mentioned, the Welsh hills
are far older than the mountains of Switzerland--has ground down the
once lofty summits and reduced them to mere stumps, such as, if the
present forces are left to work out their results, the Swiss mountains
will be thousands, or rather tens of thousands, of years hence.
The "snow line" in Switzerland is generally given as being between 8500
and 9000 feet. Above this level the snow or _névé_ gradually accumulates
until it forms "glaciers," solid rivers of ice which descend more or
less far down the valleys. No one who has not seen a glacier can
possibly realise what they are like. Fig. 20 represents the glacier of
the Blümlis Alp, and the Plate the Mer de Glace.
[Illustration: Fig. 20.--Glacier of the Blümlis Alp.]
[Illustration: THE MER DE GLACE.
_To face page 229._]
They are often very beautiful. "Mount Beerenberg," says Lord Dufferin,
"in size, colour, and effect far surpassed anything I had anticipated.
The glaciers were quite an unexpected element of beauty. Imagine a
mighty river, of as great a volume as the Thames, started down the side
of a mountain, bursting over every impediment, whirled into a thousand
eddies, tumbling and raging on from ledge to ledge in quivering
cataracts of foam, then suddenly struck rigid by a power so
instantaneous in its action that even the froth and fleeting wreaths of
spray have stiffened to the immutability of sculpture. Unless you had
seen it, it would be almost impossible to conceive the strangeness of
the contrast between the actual tranquillity of these silent crystal
rivers and the violent descending energy impressed upon their exterior.
You must remember too all this is upon a scale of such prodigious
magnitude, that when we succeeded subsequently in approaching the
spot--where with a leap like that of Niagara one of these glaciers
plunges down into the sea--the eye, no longer able to take in its
fluvial character, was content to rest in simple astonishment at what
then appeared a lucent precipice of grey-green ice, rising to the height
of several hundred feet above the masts of the vessel."[45]
The cliffs above glaciers shower down fragments of rock which gradually
accumulate at the sides and at the end of the glaciers, forming mounds
known as "moraines." Many ancient moraines occur far beyond the present
region of glaciers.
In considering the condition of alpine valleys we must remember that the
glaciers formerly descended much further than they do at present. The
glaciers of the Rhone for instance occupied the whole of the Valais,
filled the Lake of Geneva--or rather the site now occupied by that
lake--and rose 2000 feet up the slopes of the Jura; the Upper Ticino,
and contributory valleys, were occupied by another which filled the
basin of the Lago Maggiore; a third occupied the valley of the Dora
Baltea, and has left a moraine at Ivrea some twenty miles long, and
which rises no less than 1500 feet above the present level of the river.
The Scotch and Scandinavian valleys were similarly filled by rivers of
ice, which indeed at one time covered the whole country with an immense
sheet, as Greenland is at present. Enormous blocks of stone, the Pierre
à Niton at Geneva and the Pierre à Bot above Neuchâtel, for instance,
were carried by these glaciers for miles and miles; and many of the
stones in the Norfolk cliffs were brought by ice from Norway (perhaps,
however, by Icebergs), across what is now the German Ocean. Again
wherever the rocks are hard enough to have withstood the weather, we
find them polished and ground, just as, and even more so than, those at
the ends and sides of existing glaciers.
The most magnificent glacier tracks in the Alps are, in Ruskin's
opinion, those on the rocks of the great angle opposite Martigny; the
most interesting those above the channel of the Trient between Valorsine
and the valley of the Rhone.
In Great Britain I know no better illustration of ice action than is to
be seen on the road leading down from Glen Quoich to Loch Hourn, one of
the most striking examples of desolate and savage scenery in Scotland.
Its name in Celtic is said to mean the Lake of Hell. All along the
roadside are smoothed and polished hummocks of rock, most of them deeply
furrowed with approximately parallel striæ, presenting a gentle slope on
the upper end, and a steep side below, clearly showing the direction of
the great ice flow.
Many of the upper Swiss valleys contain lakes, as, for instance, that of
the Upper Rhone, the Lake of Geneva, of the Reuss, the Lake of Lucerne,
of the Rhine, that of Constance. These lakes are generally very deep.
The colour of the upper rivers, which are white with the diluvium from
the glaciers, is itself evidence of the erosive powers which they
exercise. This finely-divided matter is, however, precipitated in the
lakes, which, as well as the rivers issuing from them, are a beautiful
rich blue.
"Is it not probable that this action of finely-divided matter may have
some influence on the colour of some of the Swiss lakes--as that of
Geneva for example? This lake is simply an expansion of the river Rhone,
which rushes from the end of the Rhone glacier, as the Arveiron does
from the end of the Mer de Glace. Numerous other streams join the Rhone
right and left during its downward course; and these feeders, being
almost wholly derived from glaciers, join the Rhone charged with the
finer matter which these in their motion have ground from the rocks over
which they have passed. But the glaciers must grind the mass beneath
them to particles of all sizes, and I cannot help thinking that the
finest of them must remain suspended in the lake throughout its entire
length. Faraday has shown that a precipitate of gold may require months
to sink to the bottom of a bottle not more than five inches high, and in
all probability it would require ages of calm subsidence to bring all
the particles which the Lake of Geneva contains to its bottom. It seems
certainly worthy of examination whether such particles suspended in the
water contribute to the production of that magnificent blue which has
excited the admiration of all who have seen it under favourable
circumstances."[46]
Among the Swiss mountains themselves each has its special character.
Tyndall thus describes a view in the Alps, certainly one of the most
beautiful--that, namely, from the summit of the Ægischhorn.
"Skies and summits are to-day without a cloud, and no mist or turbidity
interferes with the sharpness of the outlines. Jungfrau, Monk, Eiger,
Trugberg, cliffy Strahlgrat, stately lady-like Aletschhorn, all grandly
pierce the empyrean. Like a Saul of Mountains, the Finsteraarhorn
overtops all his neighbours; then we have the Oberaarhorn, with the
riven glacier of Viesch rolling from his shoulders. Below is the
Mârjelin See, with its crystal precipices and its floating icebergs,
snowy white, sailing on a blue green sea. Beyond is the range which
divides the Valais from Italy. Sweeping round, the vision meets an
aggregate of peaks which look as fledglings to their mother towards the
mighty Dom. Then come the repellent crags of Mont Cervin; the ideal of
moral savagery, of wild untameable ferocity, mingling involuntarily with
our contemplation of the gloomy pile. Next comes an object, scarcely
less grand, conveying, it may be, even a deeper impression of majesty
and might than the Matterhorn itself--the Weisshorn, perhaps the most
splendid object in the Alps. But beauty is associated with its force,
and we think of it, not as cruel, but as grand and strong. Further to
the right the great Combin lifts up his bare head; other peaks crowd
around him; while at the extremity of the curve round which our gaze has
swept rises the sovran crown of Mont Blanc. And now, as day sinks,
scrolls of pearly clouds draw themselves around the mountain crests,
being wafted from them into the distant air. They are without colour of
any kind; still, by grace of form, and as the embodiment of lustrous
light and most tender shade, their beauty is not to be described."[47]
VOLCANOES
Volcanoes belong to a totally different series of mountains.
It is practically impossible to number the Volcanoes on our earth.
Humboldt enumerated 223, which Keith Johnston raised to nearly 300.
Some, no doubt, are always active, but in the majority the eruptions are
occasional, and though some are undoubtedly now extinct, it is
impossible in all cases to distinguish those which are only in repose
from those whose day of activity is over. Then, again, the question
would arise, which should be regarded as mere subsidiary cones and which
are separate volcanoes. The slopes of Etna present more than 700 small
cones, and on Hawaii there are several thousands. In fact, most of the
very lofty volcanoes present more or less lateral cones.
The molten matter, welling up through some fissure, gradually builds
itself up into a cone, often of the most beautiful regularity, such as
the gigantic peaks of Chimporazo, Cotopaxi (Fig. 21), and Fusiyama, and
hence it is that the crater is so often at, or very near, the summit.
[Illustration: Fig. 21.--Cotopaxi.]
Perhaps no spectacle in Nature is more magnificent than a Volcano in
activity. It has been my good fortune to have stood more than once at
the edge of the crater of Vesuvius during an eruption, to have watched
the lava seething below, while enormous stones were shot up high into
the air. Such a spectacle can never be forgotten.
The most imposing crater in the world is probably that of Kilauea, at a
height of about 4000 feet on the side of Mouna Loa, in the Island of
Hawaii. It has a diameter of 2 miles, and is elliptic in outline, with a
longer axis of about 3, and a circumference of about 7 miles. The
interior is a great lake of lava, the level of which is constantly
changing. Generally, it stands about 800 feet below the edge, and the
depth is about 1400 feet. The heat is intense, and, especially at night,
when the clouds are coloured scarlet by the reflection from the molten
lava, the effect is said to be magnificent. Gradually the lava mounts in
the crater until it either bursts through the side or runs over the
edge, after which the crater remains empty, sometimes for years.
A lava stream flows down the slope of the mountain like a burning river,
at first rapidly, but as it cools, scoriæ gradually form, and at length
the molten matter covers itself completely (Fig. 22), both above and at
the sides, with a solid crust, within which, as in a tunnel, it
continues to flow slowly as long as it is supplied from the source, here
and there breaking through the crust which, as continually, re-forms in
front. Thus the terrible, inexorable river of fire slowly descends,
destroying everything in its course.
[Illustration: Fig. 22.--Lava Stream.]
The stream of lava which burst from Mouna Loa in 1885 had a length of 70
miles; that of Skaptar-Jokul in Iceland in 1783 had a length of 50
miles, and a maximum depth of nearly 500 feet. It has been calculated
that the mass of lava equalled that of Mont Blanc.
The stones, ashes, and mud ejected during eruptions are even more
destructive than the rivers of lava. In 1851 Tomboro, a volcano on the
Island of Sumbava, cost more lives than fell in the battle of Waterloo.
The earthquake of Lisbon in 1755 destroyed 60,000 persons. During the
earthquake of Riobamba and the mud eruption of Tunguragua, and again in
that of Krakatoa, it is estimated that the number who perished was
between 30,000 and 40,000. At the earthquake of Antioch in 526 no less
than 200,000 persons are said to have lost their lives.
Perhaps the most destructive eruption of modern times has been that on
Cosequina. For 25 miles it covered the ground with muddy water 16 feet
in depth. The dust and ashes formed a dense cloud, extending over many
miles, some of it being carried 20 degrees to the west. The total mass
ejected has been estimated at 60 milliards of square yards.
Stromboli, in the Mediterranean (Fig. 23), though only 2500 feet in
height, is very imposing from its superb regularity, and its roots
plunge below the surface to a depth of 4000 feet.
It is, moreover, very interesting from the regularity of its action,
which has a period of 5 minutes or a little less. On looking down into
the crater one sees at a depth of say 300 feet a seething mass of
red-hot lava; this gradually rises, and then explodes, throwing up a
cloud of vapour and stones, after which it sinks again. So regular is it
that the Volcano has been compared to a "flashing" lighthouse, and this
wonderful process has been going on for ages.
[Illustration: Fig. 23.--Stromboli, viewed from the north-west, April
1874.]
Though long extinct, volcanoes once existed in the British Isles;
Arthur's Seat, near Edinburgh, for instance, appears to be the funnel of
a small volcano, belonging to the Carboniferous period.
The summit of a volcanic mountain is sometimes entirely blown away.
Between my first two visits to Vesuvius 200 feet of the mountain had
thus disappeared. Vesuvius itself stands in a more ancient crater, part
of which still remains, and is now known as Somma, the greater portion
having disappeared in the great eruption of 79, when the mountain,
waking from its long sleep, destroyed Herculaneum and Pompeii.
As regards the origin of volcanoes there have been two main theories.
Impressed by the magnitude and grandeur of the phenomena, enhanced as
they are by their destructive character, many have been disposed to
regard the craters of volcanoes as gigantic chimneys, passing right
through the solid crust of the globe, and communicating with a central
fire. Recent researches, however, have indicated that, grand and
imposing as they are, volcanoes must yet be regarded as due mainly to
local and superficial causes.
A glance at the map shows that volcanoes are almost always situated on,
or near, the sea coast. From the interior of continents they are
entirely wanting. The number of active volcanoes in the Andes,
contrasted with their absence in the Alps and Ourals, the Himalayas, and
Central Asian chains, is very striking. Indeed, the Pacific Ocean is
encircled, as Ritter has pointed out, by a ring of fire. Beginning with
New Zealand, we have the Volcanoes of Tongariro, Whakaii, etc.; thence
the circle passes through the Fiji Islands, Solomon Islands, New Guinea,
Timor, Flores, Sumbava, Lombock, Java, Sumatra, the Philippines, Japan,
the Aleutian Islands, along the Rocky Mountains, Mexico, Peru, and
Chili, to Tierra del Fuego, and, in the far south, to the two great
Volcanoes of Erebus and Terror on Victoria Land.
We know that the contraction of the Earth's surface with the strains and
fractures, the compression and folds, which must inevitably result, is
still in operation, and must give rise to areas of high temperature,
and consequently to volcanoes. We must also remember that the real
mountain chains of our earth are the continents, compared to which even
the Alps and Andes are mere wrinkles. It is along the lines of the great
mountain chains, that is to say, along the main coast lines, rather than
in the centres of the continents, which may be regarded as comparatively
quiescent, that we should naturally expect to find the districts of
greatest heat, and this is perhaps why volcanoes are generally
distributed along the coast lines.
Another reason for regarding Volcanoes as local phenomena is that many
even of those comparatively near one another act quite independently.
This is so with Kilauea and Mouna Loa, both on the small island of
Hawaii.
Again, if volcanoes were in connection with a great central sea of fire,
the eruptions must follow the same laws as regulate the tides. This,
however, is not the case. There are indeed indications of the existence
of slight tides in the molten lake which underlies Vesuvius, and during
the eruption of 1865 there was increased activity twice a day, as we
should expect to find in any great fluid reservoir, but very different
indeed from what must have been the case if the mountain was in
connection with a central ocean of molten matter.
Indeed, unless the "crust" of our earth was of great thickness we should
be subject to perpetual earthquakes. No doubt these are far more
frequent than is generally supposed; indeed, with our improved
instruments it can be shown that instead of occasional vibrations, with
long intermediate periods of rest, we have in reality short intervals of
rest with long periods of vibration, or rather perhaps that the crust of
the earth is in constant tremor, with more violent oscillation from time
to time.
It appears, moreover, that earthquakes are not generally deep-seated.
The point at which the shock is vertical can be ascertained, and it is
also possible in some cases to determine the angle at which it emerges
elsewhere. When this has been done it has always been found that the
seat of disturbance must have been within 30 geographical miles of the
surface.
Yet, though we cannot connect volcanic action with the central heat of
the earth, but must regard it as a minor and local manifestation of
force, volcanoes still remain among the grandest, most awful, and at the
same time most magnificent spectacles which the earth can afford.
FOOTNOTES:
[38] Ruskin.
[39] _The Glaciers of the Alps._
[40] Ossian.
[41] Bullar, _Azores_.
[42] Tennyson.
[43] See especially Heim's great work, _Unt. ü. d. Mechanismus der
Gebirgsbildung_.
[44] In the last 150 years more than 1000 are recorded.
[45] _Letters from High Latitudes._
[46] _Glaciers of the Alps._
[47] _Mountaineering in 1861._
CHAPTER VII
WATER
Of all inorganic substances, acting in their own proper nature,
and without assistance or combination, water is the most
wonderful. If we think of it as the source of all the
changefulness and beauty which we have seen in the clouds; then
as the instrument by which the earth we have contemplated was
modelled into symmetry, and its crags chiselled into grace;
then as, in the form of snow, it robes the mountains it has
made, with that transcendent light which we could not have
conceived if we had not seen; then as it exists in the foam of
the torrent, in the iris which spans it, in the morning mist
which rises from it, in the deep crystalline pools which mirror
its hanging shore, in the broad lake and glancing river,
finally, in that which is to all human minds the best emblem of
unwearied, unconquerable power, the wild, various, fantastic,
tameless unity of the sea; what shall we compare to this
mighty, this universal element, for glory and for beauty? or
how shall we follow its eternal cheerfulness of feeling? It is
like trying to paint a soul.--RUSKIN.
[Illustration: RYDAL WATER. _To face page 251._]
CHAPTER VII
WATER
In the legends of ancient times running water was proof against all
sorcery and witchcraft:
No spell could stay the living tide
Or charm the rushing stream.[48]
There was much truth as well as beauty in this idea.
Flowing waters, moreover, have not only power to wash out material
stains, but they also clear away the cobwebs of the brain--the results
of over incessant work--and restore us to health and strength.
Snowfields and glaciers, mountain torrents, sparkling brooks, and
stately rivers, meres and lakes, and last, not least, the great ocean
itself, all alike possess this magic power.
"When I would beget content," says Izaak Walton, "and increase
confidence in the power and wisdom and providence of Almighty God, I
will walk the meadows by some gliding stream, and there contemplate the
lilies that take no care, and those very many other little living
creatures that are not only created, but fed (man knows not how) by the
goodness of the God of Nature, and therefore trust in Him;" and in his
quaint old language he craves a special blessing on all those "that are
true lovers of virtue, and dare trust in His Providence, and be quiet,
and go a angling."
At the water's edge flowers are especially varied and luxuriant, so that
the banks of a river are a long natural garden of tall and graceful
grasses and sedges, the Meadow Sweet, the Flowering Rush, the sweet
Flag, the Bull Rush, Purple Loosestrife, Hemp Agrimony, Dewberry,
Forget-me-not, and a hundred more, backed by Willows, Alders, Poplars,
and other trees.
The Animal world, if less conspicuous to the eye, is quite as
fascinating to the imagination. Here and there a speckled Trout may be
detected (rather by the shadow than the substance) suspended in the
clear water, or darting across a shallow; if we are quiet we may see
Water Hens or Wild Ducks swimming among the lilies, a Kingfisher sitting
on a branch or flashing away like a gleam of light; a solemn Heron
stands maybe at the water's edge, or slowly rises flapping his great
wings; Water Rats, neat and clean little creatures, very different from
their coarse brown namesakes of the land, are abundant everywhere; nor
need we even yet quite despair of seeing the Otter himself.
Insects of course are gay, lively, and innumerable; but after all the
richest fauna is that visible only with a microscope.
"To gaze," says Dr. Hudson, "into that wonderful world which lies in a
drop of water, crossed by some stems of green weed, to see transparent
living mechanism at work, and to gain some idea of its modes of action,
to watch a tiny speck that can sail through the prick of a needle's
point; to see its crystal armour flashing with ever varying tint, its
head glorious with the halo of its quivering cilia; to see it gliding
through the emerald stems, hunting for its food, snatching at its prey,
fleeing from its enemy, chasing its mate (the fiercest of our passions
blazing in an invisible speck); to see it whirling in a mad dance, to
the sound of its own music, the music of its happiness, the exquisite
happiness of living--can any one, who has once enjoyed this sight, ever
turn from it to mere books and drawings, without the sense that he has
left all Fairyland behind him?"[49]
The study of Natural History has indeed the special advantage of
carrying us into the country and the open air.
Lakes are even more restful than rivers or the sea. Rivers are always
flowing, though it may be but slowly; the sea may rest awhile, now and
then, but is generally full of action and energy; while lakes seem to
sleep and dream. Lakes in a beautiful country are like silver ornaments
on a lovely dress, like liquid gems in a beautiful setting, or bright
eyes in a lovely face. Indeed as we gaze down on a lake from some hill
or cliff it almost looks solid, like some great blue crystal.
[Illustration: WINDERMERE. _To face page 254._]
It is not merely for purposes of commerce or convenience that men love
to live near rivers.
Let me live harmlessly, and near the brink
Of Trent or Avon have my dwelling-place;
Where I may see my quill, or cork, down sink,
With eager bite of pike, or bleak, or dace;
And on the world and my Creator think:
While some men strive ill-gotten goods t' embrace:
And others spend their time in base excess
Of wine; or worse, in war, or wantonness.
Let them that will, these pastimes still pursue,
And on such pleasing fancies feed their fill:
So I the fields and meadows green may view
And daily by fresh rivers walk at will,
Among the daisies and the violets blue,
Red hyacinth and yellow daffodil.[50]
It is interesting and delightful to trace a river from its source to the
sea.
"Beginning at the hill-tops," says Geikie, "we first meet with the
spring or 'well-eye,' from which the river takes its rise. A patch of
bright green, mottling the brown heathy slope, shows where the water
comes to the surface, a treacherous covering of verdure often concealing
a deep pool beneath. From this source the rivulet trickles along the
grass and heath, which it soon cuts through, reaching the black, peaty
layer below, and running in it for a short way as in a gutter.
Excavating its channel in the peat, it comes down to the soil, often a
stony earth bleached white by the peat. Deepening and widening the
channel as it gathers force with the increasing slope, the water digs
into the coating of drift or loose decomposed rock that covers the
hillside. In favourable localities a narrow precipitous gully, twenty or
thirty feet deep, may thus be scooped out in the course of a few years."
If, however, we trace one of the Swiss rivers to its source we shall
generally find that it begins in a snow field or _névé_ nestled in a
shoulder of some great mountain.
Below the _névé_ lies a glacier, on, in, and under which the water runs
in a thousand little streams, eventually emerging at the end, in some
cases forming a beautiful blue cavern, though in others the end of the
glacier is encumbered and concealed by earth and stones.
[Illustration: Fig. 24.--Upper Valley of St. Gotthard.]
The uppermost Alpine valleys are perhaps generally, though by no means
always, a little desolate and severe, as, for instance, that of St.
Gotthard (Fig. 24). The sides are clothed with rough pasture, which is
flowery indeed, though of course the flowers are not visible at a
distance, interspersed with live rock and fallen masses, while along the
bottom rushes a white torrent. The snowy peaks are generally more or
less hidden by the shoulders of the hills.
The valleys further down widen and become more varied and picturesque.
The snowy peaks and slopes are more often visible, the "alps" or
pastures to which the cows are taken in summer, are greener and dotted
with the huts or châlets of the cow-herds, while the tinkling of the
cowbells comes to one from time to time, softened by distance, and
suggestive of mountain rambles. Below the alps there is generally a
steeper part clothed with Firs or with Larches and Pines, some of which
seem as if they were scaling the mountains in regiments, preceded by a
certain number of skirmishers. Below the fir woods again are Beeches,
Chestnuts, and other deciduous trees, while the central cultivated
portion of the valley is partly arable, partly pasture, the latter
differing from our meadows in containing a greater variety of
flowers--Campanulas, Wild Geraniums, Chervil, Ragged Robin, Narcissus,
etc. Here and there is a brown village, while more or less in the centre
hurries along, with a delightful rushing sound, the mountain torrent, to
which the depth, if not the very existence of the valley, is mainly due.
The meadows are often carefully irrigated, and the water power is also
used for mills, the streams seeming to rush on, as Ruskin says, "eager
for their work at the mill, or their ministry to the meadows."
Apart from the action of running water, snow and frost are continually
disintegrating the rocks, and at the base of almost any steep cliff may
be seen a slope of debris (as in Figs. 25, 26). This stands at a regular
angle--the angle of repose--and unless it is continually removed by a
stream at the base, gradually creeps up higher and higher, until at last
the cliff entirely disappears.
[Illustration: Fig. 25.--Section of a river valley. The dotted line
shows a slope or talus of debris.]
Sometimes the two sides of the valley approach so near that there is not
even room for the river and the road: in that case Nature claims the
supremacy, and the road has to be carried in a cutting, or perhaps in a
tunnel through the rock. In other cases Nature is not at one with
herself. In many places the debris from the rocks above would reach
right across the valley and dam up the stream. Then arises a struggle
between rock and river, but the river is always victorious in the end;
even if dammed back for a while, it concentrates its forces, rises up
the rampart of rock, rushes over triumphantly, resumes its original
course, and gradually carries the enemy away.
[Illustration: Fig. 26.--Valley of the Rhone, with the waterfall of
Sallenches, showing talus of debris.]
Another prominent feature in many valleys is afforded by the old river,
or lake, terraces, which were formed at a time when the river ran at a
level far above its present bed.
Thus many a mountain valley gives some such section as the following.
[Illustration: Fig. 27.--_A_, present river valley; _B_, old river
terrace.]
First, a face of rock, very steep, and in some places almost
perpendicular; secondly, a regular talus of fallen rocks, stones, etc.,
as shown in the view of the Rhone Valley (Fig. 26), which takes what is
known as the slope of repose, at an angle which depends on the character
of the material. As a rule for loose rock fragments it may be taken
roughly to be an angle of about 45°. Then an irregular slope followed in
many places by one or more terraces, and lastly the present bed of the
river.
[Illustration: Fig. 28.--Diagram of an Alpine valley showing a river
cone. Front view.]
The width or narrowness of the valley in relation to its depth depends
greatly on the condition of the rocks, the harder and tougher they are
the narrower as a rule being the valley.
From time to time a side stream enters the main valley. This is itself
composed of many smaller rivulets. If the lateral valleys are steep, the
streams bring with them, especially after rains, large quantities of
earth and stones. When, however, they reach the main valley, the
rapidity of the current being less, their power of transport also
diminishes, and they spread out the material which they carry down in a
depressed cone (Figs. 28, 29, 31, 32).
A side stream with its terminal cone, when seen from the opposite side
of the valley, presents the appearance shown in Figs. 28, 31, or, if we
are looking down the valley, as in Figs. 29, 32, the river being often
driven to one side of the main valley, as, for instance, is the case in
the Valais, near Sion, where the Rhone (Fig. 30) is driven out of its
course by, and forms a curve round, the cone brought down by the torrent
of the Borgne.
[Illustration: Fig. 29.--Diagram of an Alpine valley, showing a river
cone. Lateral view.]
Sometimes two lateral valleys (see Plate) come down nearly opposite one
another, so that the cones meet, as, for instance, some little way below
Vernayaz, and, indeed, in several other places in the Valais (Fig. 31).
Or more permanent lakes may be due to a ridge of rock running across the
valley, as, for instance, just below St. Maurice in the Valais.
[Illustration: Fig. 30.]
[Illustration: VIEW IN THE VALAIS BELOW ST. MAURICE. _To face page
266._]
[Illustration: Fig. 31.--View in the Rhone Valley, showing a lateral
cone.]
Almost all river valleys contain, or have contained, in their course one
or more lakes, and where a river falls into a lake a cone like those
just described is formed, and projects into the lake. Thus on the Lake
of Geneva, between Vevey and Villeneuve (see Fig. 33), there are several
such promontories, each marking the place where a stream falls into the
lake.
[Illustration: Fig. 32.--View in the Rhone Valley, showing the slope of
a river cone.]
The Rhone itself has not only filled up what was once the upper end of
the lake, but has built out a strip of land into the water.
[Illustration: Fig. 33.--Shore of the Lake of Geneva, near Vevey.]
That the lake formerly extended some distance up the Valais no one can
doubt who looks at the flat ground about Villeneuve. The Plate
opposite, from a photograph taken above Vevey, shows this clearly. It is
quite evident that the lake must formerly have extended further up the
valley, and that it has been filled up by material brought down by the
Rhone, a process which is still continuing.
At the other end of the lake the river rushes out 15 feet deep of "not
flowing, but flying water; not water neither--melted glacier matter, one
should call it; the force of the ice is in it, and the wreathing of the
clouds, the gladness of the sky, and the countenance of time."[51]
[Illustration: VIEW UP THE VALAIS FROM THE LAKE OF GENEVA. _To face page
270._]
In flat countries the habits of rivers are very different. For instance,
in parts of Norfolk there are many small lakes or "broads" in a network
of rivers--the Bure, the Yare, the Ant, the Waveney, etc.--which do not
rush on with the haste of some rivers, or the stately flow of others
which are steadily set to reach the sea, but rather seem like rivers
wandering in the meadows on a holiday. They have often no natural banks,
but are bounded by dense growths of tall grasses, Bulrushes, Reeds, and
Sedges, interspersed with the spires of the purple Loosestrife, Willow
Herb, Hemp Agrimony, and other flowers, while the fields are very low
and protected by dykes, so that the red cattle appear to be browsing
below the level of the water; and as the rivers take most unexpected
turns, the sailing boats often seem (Fig. 34) as if they were in the
middle of the fields.
[Illustration: Fig. 34.--View in the district of the Broads, Norfolk.]
At present these rivers are restrained in their courses by banks; when
left free they are continually changing their beds. Their courses at
first sight seem to follow no rule, but, as it is termed, from a
celebrated river of Asia Minor, to "meander" along without aim or
object, though in fact they follow very definite laws.
Finally, when the river at length reaches the sea, it in many cases
spreads out in the form of a fan, forming a very flat cone or "delta,"
as it is called, from the Greek capital [Greek: Delta], a name first
applied to that of the Nile, and afterwards extended to other rivers.
This is due to the same cause, and resembles, except in size, the
comparatively minute cones of mountain streams.
[Illustration: Fig. 35.]
Fig. 35 represents the delta of the Po, and it will be observed that
Adria, once a great port, and from which the Adriatic was named, is now
more than 20 miles from the sea. Perhaps the most remarkable case is
that of the Mississippi (Fig. 36), the mouths of which project into the
sea like a hand, or like the petals of a flower. For miles the mud is
too soft to support trees, but is covered by sedges (Miegea); the banks
of mud gradually become too soft and mobile even for them. The pilots
who navigate ships up the river live in frail houses resting on planks,
and kept in place by anchors. Still further, and the banks of the
Mississippi, if banks they can be called, are mere strips of reddish
mud, intersected from time to time by transverse streams of water, which
gradually separate them into patches. These become more and more
liquid, until the land, river, and sea merge imperceptibly into one
another. The river is so muddy that it might almost be called land, and
the mud so saturated by water that it might well be called sea, so that
one can hardly say whether a given spot is on the continent, in the
river, or on the open ocean.
[Illustration: Fig. 36.]
FOOTNOTES:
[48] Leyden.
[49] Dr. Hudson, Address to the Microscopical Society, 1889.
[50] F. Davors.
[51] Ruskin.
CHAPTER VIII
RIVERS AND LAKES
ON THE DIRECTIONS OF RIVERS
In the last chapter I have alluded to the wanderings of rivers within
the limits of their own valleys; we have now to consider the causes
which have determined the directions of the valleys themselves.
If a tract of country were raised up in the form of a boss or dome, the
rain which fell on it would partly sink in, partly run away to the lower
ground. The least inequality in the surface would determine the first
directions of the streams, which would carry down any loose material,
and thus form little channels, which would be gradually deepened and
enlarged. It is as difficult for a river as for a man to get out of a
groove.
In such a case the rivers would tend to radiate with more or less
regularity from the centre or axis of the dome, as, for instance, in our
English lake district (Fig. 37). Derwent Water, Thirlmere, Coniston
Water, and Windermere, run approximately N. and S.; Crummock Water,
Loweswater, and Buttermere N.W. by S.E.; Waste Water, Ullswater, and
Hawes Water N.E. by S.W.; while Ennerdale Water lies nearly E. by W. Can
we account in any way, and if so how, for these varied directions?
The mountains of Cumberland and Westmoreland form a more or less oval
boss, the axis of which, though not straight, runs practically from
E.N.E. to W.S.W., say from Scaw Fell to Shap Fell; and a sketch map
shows us almost at a glance that Derwent Water, Thirlmere, Ullswater,
Coniston Water, and Windermere run at right angles to this axis;
Ennerdale Water is just where the boss ends and the mountains disappear;
while Crummock Water and Waste Water lie at the intermediate angles.
[Illustration: Fig. 37.--Map of the Lake District.]
So much then for the direction. We have still to consider the situation
and origin, and it appears that Ullswater, Coniston Water, the River
Dudden, Waste Water, and Crummock Water lie along the lines of old
faults, which no doubt in the first instance determined the flow of the
water.
Take another case. In the Jura the valleys are obviously (see Fig. 18)
in many cases due to the folding of the strata. It seldom happens,
however, that the case is so simple. If the elevation is considerable
the strata are often fractured, and fissures are produced. Again if the
part elevated contains layers of more than one character, this at once
establishes differences. Take, for instance, the Weald of Kent (Figs.
38, 39). Here we have (omitting minor layers) four principal strata
concerned, namely, the Chalk, Greensand, Weald Clay, and Hastings
Sands.
[Illustration: Fig. 38.--_a_, _a_, Upper Cretaceous strata, chiefly
Chalk, forming the North and South Downs; _b_, _b_, Escarpment of Lower
Greensand, with a valley between it and the Chalk; _c_, _c_, Weald Clay,
forming plains; _d_, Hills formed of Hastings Sand and Clay. The Chalk,
etc., once spread across the country, as shown in the dotted lines.]
The axis of elevation runs (Fig. 39) from Winchester by Petersfield,
Horsham, and Winchelsea to Boulogne, and as shown in the following
section, taken from Professor Ramsay, we have on each side of the axis
two ridges or "escarpments," one that of the Chalk, the other that of
the Greensand, while between the Chalk and the Greensand is a valley,
and between the Greensand and the ridge of Hastings Sand an undulating
plain, in each case with a gentle slope from about where the London and
Brighton railway crosses the Weald towards the east. Under these
circumstances we might have expected that the streams draining the Weald
would have run in the direction of the axis of elevation, and at the
bases of the escarpments, as in fact the Rother does for part of its
course, into the sea between the North and South Downs, instead of which
as a rule they run north and south, cutting in some cases directly
through the escarpments; on the north, for instance, the Wye, the Mole,
the Darenth, the Medway, and the Stour; and on the south the Arun, the
Addur, the Ouse, and the Cuckmere.
[Illustration: Fig. 39.--Map of the Weald of Kent.]
They do not run in faults or cracks, and it is clear that they could not
have excavated their present valleys under circumstances such as now
exist. They carry us back indeed to a time when the Greensand and Chalk
were continued across the Weald in a great dome, as shown by the dotted
lines in Fig. 38. They then ran down the slope of the dome, and as the
Chalk and Greensand gradually weathered back, a process still in
operation, the rivers deepened and deepened their valleys, and thus were
enabled to keep their original course.
Other evidence in support of this view is afforded by the presence of
gravel beds in some places at the very top of the Chalk escarpment--beds
which were doubtless deposited when, what is now the summit of a hill,
was part of a continuous slope.
The course of the Thames offers us a somewhat similar instance. It rises
on the Oolites near Cirencester, and cuts through the escarpment of the
Chalk between Wallingford and Reading. The cutting through the Chalk has
evidently been effected by the river itself. But this could not have
happened under existing conditions. We must remember, however, that the
Chalk escarpment is gradually moving eastwards. The Chalk escarpments
indeed are everywhere, though of course only slowly, crumbling away.
Between Farnham and Guildford the Chalk is reduced to a narrow ridge
known as the Hog's Back. In the same way no doubt the area of the Chalk
formerly extended much further west than it does at present, and,
indeed, there can be little doubt, somewhat further west than the source
of the Thames, almost to the valley of the Severn. At that time the
Thames took its origin in a Chalk spring. Gradually, however, the Chalk
was worn away by the action of weather, and especially of rain. The
river maintained its course while gradually excavating, and sinking
deeper and deeper into, the Chalk. At present the river meets the Chalk
escarpment near Wallingford, but the escarpment itself is still
gradually retreating eastward.
So, again, the Elbe cuts right across the Erz-Gebirge, the Rhine through
the mountains between Bingen and Coblenz, the Potomac, the Susquehannah,
and the Delaware through the Alleghanies. The case of the Dranse will be
alluded to further on (p. 292). In these cases the rivers preceded the
mountains. Indeed as soon as the land rose above the waters, rivers
would begin their work, and having done so, unless the rate of elevation
of the mountain exceeded the power of erosion of the river, the two
would proceed simultaneously, so that the river would not alter its
course, but would cut deeper and deeper as the mountain range gradually
rose.
Rivers then are in many cases older than mountains. Moreover, the
mountains are passive, the rivers active. Since it seems to be well
established that in Switzerland a mass, more than equal to what remains,
has been removed; and that many of the present mountains are not sites
which were originally raised highest, but those which have suffered
least, it follows that if in some cases the course of the river is due
to the direction of the mountain ridges, on the other hand the direction
of some of the present ridges is due to that of the rivers. At any rate
it is certain that of the original surface not a trace or a fragment
remains _in situ_. Many of our own English mountains were once valleys,
and many of our present valleys occupy the sites of former mountain
ridges.
Heim and Rütimeyer point out that of the two factors which have produced
the relief of mountain regions, the one, elevation, is temporary and
transitory; the other, denudation, is constant, and gains therefore
finally the upper hand.
We must not, however, expect too great regularity. The degree of
hardness, the texture, and the composition of the rocks cause great
differences.
On the other hand, if the alteration of level was too rapid, the result
might be greatly to alter the river courses. Mr. Darwin mentions such a
case, which, moreover, is perhaps the more interesting as being
evidently very recent.
"Mr. Gill," he says, "mentioned to me a most interesting, and as far as
I am aware, quite unparalleled case, of a subterranean disturbance
having changed the drainage of a country. Travelling from Casma to
Huaraz (not very far distant from Lima) he found a plain covered with
ruins and marks of ancient cultivation, but now quite barren. Near it
was the dry course of a considerable river, whence the water for
irrigation had formerly been conducted. There was nothing in the
appearance of the water-course to indicate that the river had not flowed
there a few years previously; in some parts beds of sand and gravel were
spread out; in others, the solid rock had been worn into a broad
channel, which in one spot was about 40 yards in breadth and 8 feet
deep. It is self-evident that a person following up the course of a
stream will always ascend at a greater or less inclination. Mr. Gill
therefore, was much astonished when walking up the bed of this ancient
river, to find himself suddenly going downhill. He imagined that the
downward slope had a fall of about 40 or 50 feet perpendicular. We here
have unequivocal evidence that a ridge had been uplifted right across
the old bed of a stream. From the moment the river course was thus
arched, the water must necessarily have been thrown back, and a new
channel formed. From that moment also the neighbouring plain must have
lost its fertilising stream, and become a desert."[52]
The strata, moreover, often--indeed generally, as we have seen, for
instance, in the case of Switzerland--bear evidence of most violent
contortions, and even where the convulsions were less extreme, the
valleys thus resulting are sometimes complicated by the existence of
older valleys formed under previous conditions.
In the Alps then the present configuration of the surface is mainly the
result of denudation. If we look at a map of Switzerland we can trace
but little relation between the river courses and the mountain chains.
[Illustration: Fig. 40.--Sketch Map of the Swiss Rivers.]
The rivers, as a rule (Fig. 40), run either S.E. by N.W., or, at right
angles to this, N.E. and S.W. The Alps themselves follow a somewhat
curved line from the Maritime Alps, commencing with the islands of
Hyères, by Briancon, Martigny, the Valais, Urseren Thal, Vorder Rhein,
Innsbruck, Radstadt, and Rottenmann to the Danube, a little below
Vienna,--at first nearly north and south, but gradually curving round
until it becomes S.W. by N.E.
The central mountains are mainly composed of Gneiss, Granite, and
crystalline Schists: the line of junction between these rocks and the
secondary and tertiary strata on the north, runs, speaking roughly, from
Hyères to Grenoble, and then by Albertville, Sion, Chur, Inns, bruck,
Radstadt, and Hieflau, towards Vienna. It is followed (in some part of
their course) by the Isère, the Rhone, the Rhine, the Inn, and the Enns.
One of the great folds shortly described in the preceding chapter runs
up the Isère, along the Chamouni Valley, up the Rhone, through the
Urseren Thal, down the Rhine Valley to Chur, along the Inn nearly to
Kufstein, and for some distance along the Enns. Thus, then, five great
rivers have taken advantage of this main fold, each of them eventually
breaking through into a transverse valley.
The Pusterthal in the Tyrol offers us an interesting case of what is
obviously a single valley, which has, however, been slightly raised in
the centre, near Toblach, so that from this point the water flows in
opposite directions--the Drau eastward, and the Rienz westward. In this
case the elevation is single and slight: in the main valley there are
several, and they are much loftier, still we may, I think, regard that
of the Isère from Chambery to Albertville, of the Rhone from Martigny to
its source, of the Urseren Thal, of the Vorder Rhine from its source to
Chur, of the Inn from Landeck to below Innsbruck, even perhaps of the
Enns from Radstadt to Hieflau as in one sense a single valley, due to
one of these longitudinal folds, but interrupted by bosses of gneiss and
granite,--one culminating in Mont Blanc, and another in the St.
Gotthard,--which have separated the waters of the Isère, the Rhone, the
Vorder Rhine, the Inn, and the Enns. That the valley of Chamouni, the
Valais, the Urseren Thal, and that of the Vorder Rhine really form part
of one great fold is further shown by the presence of a belt of Jurassic
strata nipped in, as it were, between the crystalline rocks.
This seems to throw light on the remarkable turns taken by the Rhone at
Martigny and the Vorder Rhine at Chur, where they respectively quit the
great longitudinal fold, and fall into secondary transverse valleys. The
Rhone for the upper part of its course, as far as Martigny, runs in the
great longitudinal fold of the Valais; at Martigny it falls into and
adopts the transverse valley, which properly belongs to the Dranse; for
the Dranse is probably an older river and ran in the present course even
before the great fold of the Valais. This would seem to indicate that
the Oberland range is not so old as the Pennine, and that its elevation
was so gradual that the Dranse was able to wear away a passage as the
ridge gradually rose. After leaving the Lake of Geneva the Rhone follows
a course curving gradually to the south, until it reaches St. Genix,
where it falls into and adopts a transverse valley which properly
belongs to the little river Guiers; it subsequently joins the Ain and
finally falls into the Saône. If these valleys were attributed to their
older occupiers we should therefore confine the name of the Rhone to the
portion of its course from the Rhone glacier to Martigny. From Martigny
it occupies successively the valleys of the Dranse, Guiers, Ain, and
Saône. In fact, the Saône receives the Ain, the Ain the Guiers, the
Guiers the Dranse, and the Dranse the Rhone. This is not a mere question
of names, but also one of antiquity. The Saône, for instance, flowed
past Lyons to the Mediterranean for ages before it was joined by the
Rhone. In our nomenclature, however, the Rhone has swallowed up the
others. This is the more curious because of the three great rivers which
unite to form the lower Rhone, namely, the Saône, the Doubs, and the
Rhone itself, the Saône brings for a large part of the year the greatest
volume of water, and the Doubs has the longest course. Other similar
cases might be mentioned. The Aar, for instance, is a somewhat larger
river than the Rhine.
[Illustration: Fig. 41.--Diagram in illustration of Mountain structure.]
But why should the rivers, after running for a certain distance in the
direction of the main axis, so often break away into lateral valleys? If
the elevation of a chain of mountains be due to the causes suggested in
p. 214, it is evident, though, so far as I am aware, stress has not
hitherto been laid upon this, that the compression and consequent
folding of the strata (Fig. 41) would not be in the direction _A B_
only, but also at right angles to it, in the direction _A C_, though the
amount of folding might be much greater in one direction than in the
other. Thus in the case of Switzerland, while the main folds run
south-west by north-east, there would be others at right angles to the
main axis. The complex structure of the Swiss mountains may be partly
due to the coexistence of these two directions of pressure at right
angles to one another. The presence of a fold so originating would often
divert the river to a course more or less nearly at right angles to its
original direction.
Switzerland, moreover, slopes northwards from the Alps, so that the
lowest part of the great Swiss plain is that along the foot of the
Jura. Hence the main drainage runs along the line from Yverdun to
Neuchâtel, down the Zihl to Soleure, and then along the Aar to Waldshut:
the Upper Aar, the Emmen, the Wiggern, the Suhr, the Wynen, the lower
Reuss, the Sihl, and the Limmat, besides several smaller streams,
running approximately parallel to one another north-north-east, and at
angles to the main axis of elevation, and all joining the Aar from the
south, while on the north it does not receive a single contributary of
any importance.
On the south side of the Alps again we have the Dora Baltea, the Sesia,
the Ticino, the Olonna, the Adda, the Adige, etc., all running
south-south-east from the axis of elevation to the Po.
[Illustration: Fig. 42.]
Indeed, the general slope of Switzerland, being from the ridge of the
Alps towards the north, it will be observed (Fig. 42) that almost all
the large affluents of these rivers running in longitudinal valleys fall
in on the south, as, for instance, those of the Isère from Albertville
to Grenoble, of the Rhone from its source to Martigny, of the Vorder
Rhine from its source to Chur, of the Inn from Landeck to Kufstein, of
the Enns from its source to near Admont, of the Danube from its source
to Vienna, and as just mentioned, of the Aar from Bern to Waldshut.
Hence also, whenever the Swiss rivers running east and west break into a
transverse valley, as the larger ones all do, and some more than once,
they invariably, whether originally running east or westwards, turn
towards the north.
But although we thus get a clue to the general structure of Switzerland,
the whole question is extremely complex, and the strata have been
crumpled and folded in the most complicated manner, sometimes completely
reversed, so that older rocks have been folded back on younger strata,
and even in some cases these folds again refolded. Moreover, the
denudation by aerial action, by glaciers, frosts, and rivers has removed
hundreds, or rather thousands, of feet of strata. In fact, the mountain
tops are not by any means the spots which have been most elevated, but
those which have been least denuded; and hence it is that so many of the
peaks stand at about the same altitude.
THE CONFLICTS AND ADVENTURES OF RIVERS
Our ancestors looked upon rivers as being in some sense alive, and in
fact in their "struggle for existence" they not only labour to adapt
their channel to their own requirements, but in many cases enter into
conflict with one another.
In the plain of Bengal, for instance, there are three great rivers, the
Brahmapootra coming from the north, the Ganges from the west, and the
Megna from the east, each of them with a number of tributary streams.
Mr. Fergusson[53] has given us a most interesting and entertaining
account of the struggles between these great rivers to occupy the
fertile plain of Bengal.
The Megna, though much inferior in size to the Brahmapootra, has one
great advantage. It depends mainly on the monsoon rains for its supply,
while the Brahmapootra not only has a longer course to run, but relies
for its floods, to a great extent, on the melting of the snow, so that,
arriving later at the scene of the struggle, it finds the country
already occupied by the Megna to such an extent that it has been driven
nearly 70 miles northwards, and forced to find a new channel.
Under these circumstances it has attacked the territory of the Ganges,
and being in flood earlier than that river, though later than the Megna,
it has in its turn a great advantage.
Whatever the ultimate result may be the struggle continues vigorously.
At Sooksaghur, says Fergusson, "there was a noble country house, built
by Warren Hastings, about a mile from the banks of the Hoogly. When I
first knew it in 1830 half the avenue of noble trees, which led from the
river to the house, was gone; when I last saw it, some eight years
afterwards, the river was close at hand. Since then house, stables,
garden, and village are all gone, and the river was on the point of
breaking through the narrow neck of high land that remained, and pouring
itself into some weak-banded nullahs in the lowlands beyond: and if it
had succeeded, the Hoogly would have deserted Calcutta. At this
juncture the Eastern Bengal Railway Company intervened. They were
carrying their works along the ridge, and they have, for the moment at
least, stopped the oscillation in this direction."
This has affected many of the other tributaries of the Ganges, so that
the survey made by Rennell in 1780-90 is no longer any evidence as to
the present course of the rivers. They may now be anywhere else; in some
cases all we can say is that they are certainly not now where they were
then.
The association of the three great European rivers, the Rhine, the
Rhone, and the Danube, with the past history of our race, invests them
with a singular fascination, and their past history is one of much
interest. They all three rise in the group of mountains between the
Galenstock and the Bernardino, within a space of a few miles; on the
east the waters run into the Black Sea, on the north into the German
Ocean, and on the west into the Mediterranean. But it has not always
been so. Their head-waters have been at one time interwoven together.
At present the waters of the Valais escape from the Lake of Geneva at
the western end, and through the remarkable defile of Fort de l'Ecluse
and Malpertius, which has a depth of 600 feet, and is at one place not
more than 14 feet across. Moreover, at various points round the Lake of
Geneva, remains of lake terraces show that the water once stood at a
level much higher than the present. One of these is rather more than 250
feet[54] above the lake.
A glance at the map will show that between Lausanne and Yverdun there is
a low tract of land, and the Venoge, which falls into the Lake of Geneva
between Lausanne and Morges, runs within about half a mile of the Nozon,
which falls into the Lake of Neuchâtel at Yverdun, the two being
connected by the Canal d'Entreroches, and the height of the watershed
being only 76 metres (250 feet), corresponding with the above mentioned
lake terrace. It is evident, therefore, that when the Lake of Geneva
stood at the level of the 250 feet terrace the waters ran out, not as
now at Geneva and by Lyons to the Mediterranean, but near Lausanne by
Cissonay and Entreroches to Yverdun, and through the Lake of Neuchâtel
into the Aar and the Rhine.
But this is not the whole of the curious history. At present the Aar
makes a sharp turn to the west at Waldshut, where it falls into the
Rhine, but there is reason to believe that at a former period, before
the Rhine had excavated its present bed, the Aar continued its course
eastward to the Lake of Constance, by the valley of the Klettgau, as is
indicated by the presence of gravel beds containing pebbles which have
been brought, not by the Rhine from the Grisons, but by the Aar from the
Bernese Oberland, showing that the river which occupied the valley was
not the Rhine but the Aar. It would seem also that at an early period
the Lake of Constance stood at a considerably higher level, and that the
outlet was, perhaps, from Frederichshaven to Ulm, along what are now the
valleys of the Schussen and the Ried, into the Danube.
Thus the head-waters of the Rhone appear to have originally run by
Lausanne and the Lake of Constance into the Danube, and so to the Black
Sea. Then, after the present valley was opened between Waldshut and
Basle, they flowed by Basle and the present Rhine, and after joining the
Thames, over the plain which now forms the German Sea into the Arctic
Ocean between Scotland and Norway. Finally, after the opening of the
passage at Fort de l'Ecluse, by Geneva, Lyons, and the Valley of the
Saône, to the Mediterranean.
It must not, however, be supposed that these changes in river courses
are confined to the lower districts. Mountain streams have also their
adventures and vicissitudes, their wars and invasions. Take for instance
the Upper Rhine, of which we have a very interesting account by Heim. It
is formed of three main branches, the Vorder Rhine, Hinter Rhine, and
the Albula. The two latter, after meeting near Thusis, unite with the
Vorder Rhine at Reichenau, and run by Chur, Mayenfeld, and Sargans into
the Lake of Constance at Rheineck. At some former period, however, the
drainage of this district was very different, as is shown in Fig. 43.
The Vorder and Hinter Rhine united then (Fig. 43) as they do now at
Reichenau, but at a much higher level, and ran to Mayenfeld, not by
Chur, but by the Kunckel Pass to Sargans, and so on, not to the Lake of
Constance, but to that of Zurich. The Landwasser at that time rose in
the Schlappina Joch, and after receiving as tributaries the Vereina and
the Sardasca, joined the Albula, as it does now at Tiefenkasten; but
instead of going round to meet the Hinter Rhine near Thusis, the two
together travelled parallel with, but at some distance from, the Hinter
Rhine, by Heide to Chur, and so to Mayenfeld.
In the meanwhile, however, the Landquart was stealthily creeping up the
valley, attacked the ridge which then united the Casanna and the
Madrishorn, and gradually forcing the passage, invaded (Fig. 44) the
valleys of the Schlappina, Vereina, and Sardasca, absorbed them as
tributaries, and, detaching them from their allegiance to the
Landwasser, annexed the whole of the upper province which had formerly
belonged to that river.
[Illustration: Fig. 43.--River system round Chur, as it used to be.]
The Schyn also gradually worked its way upwards from Thusis till it
succeeded in sapping the Albula, and carried it down the valley to join
the Vorder Rhine near Thusis. In what is now the main valley of the
Rhine above Chur another stream ate its way back, and eventually tapped
the main river at Reichenau, thus diverting it from the Kunckel, and
carrying it round by Chur.
[Illustration: Fig. 44.--River system round Chur, as it is.]
At Sargans a somewhat similar process was repeated, with the addition
that the material brought down by the Weisstannen, or perhaps a
rockfall, deflected the Rhine, just as we see in Fig. 30 that the Rhone
was pushed on one side by the Borgne. The Rhone, however, had no choice,
it was obliged to force, and has forced its way over the cone deposited
by the Borgne. The Rhine, on the contrary, had the option of running
down by Vaduz to Rheinach, and has adopted this course. The watershed
between it and the Weisstannen is, however, only about 20 feet in
height, and the people of Zurich watch it carefully, lest any slight
change should enable the river to return to its old bed. The result of
all these changes is that the rivers have changed their courses from
those shown in Fig. 43 to their present beds as shown in Fig. 44.
Another interesting case is that of the Upper Engadine (Fig. 45), to
which attention has been called by Bonney and Heim. The fall of the Val
Bregaglia is much steeper than that of the Inn, and the Maira has
carried off the head-waters of that river away into Italy. The Col was
formerly perhaps as far south as Stampa: the Albegna, the Upper Maira,
and the stream from the Forgno Glacier, originally belonged to the Inn,
but have been captured by the Lower Maira. Their direction still
indicates this; they seem as if they regretted the unwelcome change, and
yearned to rejoin their old companions.
[Illustration: Fig. 45.--River system of the Maloya.]
Moreover, as rivers are continually cutting back their valleys they must
of course sometimes meet. In these cases when the valleys are at
different levels the lower rivers have drained the upper ones, and left
dry, deserted valleys. In other cases, especially in flatter districts,
we have bifurcations, as, for instance, at Sargans, and several of the
Italian lakes. Every one must have been struck by the peculiar
bifurcation of the Lakes of Como and Lugano, while a very slight
depression would connect the Lake Varese with the Maggiore, and give it
also a double southern end.
ON LAKES
The problem of the origin of Lakes is by no means identical with that of
Valleys. The latter are due, primarily as a rule to geological causes,
but so far as their present condition is concerned, mainly to the action
of rain and rivers. Flowing water, however, cannot give rise to lakes.
It is of course possible to have valleys without lakes, and in fact the
latter are, now at least, exceptional. There can be no lakes if the
slope of the valley is uniform. To what then are lakes due?
Professor Ramsay divides Lakes into three classes:--
1. Those due to irregular accumulations of drift, and which are
generally quite shallow.
2. Those formed by moraines.
3. Those which occupy true basins scooped by glacier ice out of the
solid rock.
To these must, however, I think be added at least one other great class
and several minor ones, namely,--
4. Those due to inequalities of elevation or depression.
5. Lakes in craters of extinct volcanoes, for instance, Lake Avernus.
6. Those caused by subsidence due to the removal of underlying soluble
rocks, such as some of the Cheshire Meres.
7. Loop lakes in deserted river courses, of which there are many along
the course of the Rhine.
8. Those due to rockfalls, landslips, or lava currents, damming up the
course of a river.
9. Those caused by the advance of a glacier across a lateral valley,
such as the Mergelen See, or the ancient lake whose margins form the
celebrated "Parallel Roads of Glen Roy."
As regards the first class we find here and there on the earth's surface
districts sprinkled with innumerable shallow lakes of all sizes, down to
mere pools. Such, for instance, occur in the district of Le Doubs
between the Rhone and the Saône, that of La Sologne near Orleans, in
parts of North America, and in Finland. Such lakes are, as a rule,
quite shallow. Some geologists, Geikie, for instance, ascribe them to
the fact of these regions having been covered by sheets of ice which
strewed the land with irregular masses of clay, gravel, and sand, lying
on a stratum impervious to water, either of hard rock such as granite or
gneiss, or of clay, so that the rain cannot percolate through it, and
without sufficient inclination to throw it off.
2. To Ramsay's second class of Lakes belong those formed by moraines.
The materials forming moraines being, however, comparatively loose, are
easily cut through by streams. There are in Switzerland many cases of
valleys crossed by old moraines, but they have generally been long ago
worn through by the rivers.
3. Ramsay and Tyndall attribute most of the great Swiss and Italian
lakes to the action of glaciers, and regard them as rock basins. It is
of course obvious that rivers cannot make basin-shaped hollows
surrounded by rock on all sides. The Lake of Geneva, 1230 feet above the
sea, is over 1000 feet deep; the Lake of Brienz is 1850 feet above the
sea, and 2000 feet deep, so that its bottom is really below the sea
level. The Italian Lakes are even more remarkable. The Lake of Como, 700
feet above the sea, is 1929 feet deep. Lago Maggiore, 685 feet above the
sea, is no less than 2625 feet deep.
If the mind is at first staggered at the magnitude of the scale, we must
remember that the ice which is supposed to have scooped out the valley
in which the Lake of Geneva now reposes, was once at least 4000 feet
thick; while the moraines were also of gigantic magnitude, that of
Ivrea, for instance, being no less than 1500 feet above the river, and
several miles long.
Indeed it is obvious that a glacier many hundred, or in some cases
several thousand, feet in thickness, must exercise great pressure on the
bed over which it travels. We see this from the striæ and grooves on the
solid rocks, and the fine mud which is carried down by glacial streams.
The deposit of glacial rivers, the "loess" of the Rhine itself, is
mainly the result of this ice-waste, and that is why it is so fine, so
impalpable. That glaciers do deepen their beds seems therefore
unquestionable.
Moreover, though the depth of some of these lakes is great, the true
slope is very slight.
Tyndall and Ramsay do not deny that the original direction of valleys,
and consequently of lakes, is due to cosmical causes and geological
structure, while even those who have most strenuously opposed the theory
which attributes lakes to glacial erosion do not altogether deny the
action of glaciers. Favre himself admits that "it is impossible to deny
that valleys, after their formation, have been swept out and perhaps
enlarged by rivers and glaciers."
Even Ruskin admits "that a glacier may be considered as a vast
instrument of friction, a white sand-paper applied slowly but
irresistibly to all the roughness of the hill which it covers."
It is obvious that sand-paper applied "irresistibly" and long enough,
must gradually wear away and lower the surface. I cannot therefore
resist the conclusion that glaciers have taken an important part in the
formation of lakes.
The question has sometimes been discussed as if the point at issue were
whether rivers or glaciers were the most effective as excavators. But
this is not so. Those who believe that lakes are in many cases due to
glaciers might yet admit that rivers have greater power of erosion.
There is, however, an essential difference in the mode of action. Rivers
tend to regularise their beds; they drain, rather than form lakes. Their
tendency is to cut through any projections so that finally their course
assumes some such curve as that below, from the source (_a_) to its
entrance into the sea (_b_).
[Illustration: Fig. 46.--Final Slope of a River.]
Glaciers, however, have in addition a scooping power, so that if
similarly _a d b_ in Fig. 47 represent the course of a glacier, starting
at _a_ and gradually thinning out to _e_, it may scoop out the rock to
a certain extent at _d_; in that case if it subsequently retires say to
_c_, there would be a lake lying in the basin thus formed between _c_
and _e_.
[Illustration: Fig. 47.]
On the other hand I am not disposed to attribute the Swiss lakes
altogether to the action of glaciers. In the first place it does not
seem clear that they occupy true rock basins. On this point more
evidence is required. That some lakes are due to unequal changes of
level will hardly be denied. No one, for instance, as Bonney justly
observes,[55] would attribute the Dead Sea to glacial erosion.
The Alps, as we have seen, are a succession of great folds, and there is
reason to regard the central one as the oldest. If then the same process
continued, and the outer fold was still further raised, or a new one
formed, more quickly than the rivers could cut it back, they would be
dammed up, and lakes would result.
Moreover, if the formation of a mountain region be due to subsidence,
and consequent crumpling, as indicated on p. 217, so that the strata
which originally occupied the area A B C D are compressed into A' B' C'
D', it is evident, as already mentioned, that while the line of least
resistance, and, consequently, the principal folds might be in the
direction A' B', there must also be a tendency to the formation of
similar folds at right angles, or in the direction A' C'. Thus, in the
case of Switzerland, while the main folds run south-west by north-east
there would also be others at right angles, though the amount of folding
might be much greater in the one direction than in the other. To this
cause the bosses, for instance--at Martigny, the Furca, and the Ober
Alp,--which intersect the great longitudinal valley of Switzerland, are
perhaps due.
The great American lakes also are probably due to differences of
elevation. Round Lake Ontario, for instance, there is a raised beach
which at the western end of the lake is 363 feet above the sea level,
but rises towards the East and North until near Fine it reaches an
elevation of 972 feet. As this terrace must have been originally
horizontal we have here a lake barrier, due to a difference of
elevation, amounting to over 600 feet.
In the same way we get a clue to the curious cruciform shape of the Lake
of Lucerne as contrasted with the simple outline of such lakes as those
of Neuchâtel or Zurich. That of Lucerne is a complex lake. Soundings
have shown that the bottom of the Urner See is quite flat. It is in fact
the old bed of the Reuss, which originally ran, not as now by Lucerne,
but by Schwytz and through the Lake of Zug. In the same way the Alpnach
See is the old bed of the Aa, which likewise ran through the Lake of
Zug. The old river terraces of the Reuss can be traced in places between
Brunnen and Goldau. Now these terraces must have originally sloped from
the upper part downwards, from Brunnen towards Goldau. But at present
the slope is the other way, _i.e._ from Goldau towards Brunnen. From
this and other evidence we conclude that in the direction from Lucerne
towards Rapperschwyl there has been an elevation of the land, which has
dammed up the valleys and thus turned parts of the Aa and the Reuss into
lakes--the two branches of the Lake of Lucerne known as the Alpnach See
and Urner See.
During the earthquakes of 1819 while part of the Runn of Cutch, 2000
square miles in area, sunk several feet, a ridge of land, called by the
natives the Ulla-Bund or "the wall of God," thirty miles long, and in
parts sixteen miles wide, was raised across an ancient arm of the Indus,
and turned it temporarily into a lake.
In considering the great Italian lakes, which descend far below the sea
level, we must remember that the Valley of the Po is a continuation of
the Adriatic, now filled up and converted into land, by the materials
brought down from the Alps. Hence we are tempted to ask whether the
lakes may not be remains of the ancient sea which once occupied the
whole plain. Moreover just as the Seals of Lake Baikal in Siberia carry
us back to the time when that great sheet of fresh water was in
connection with the Arctic Ocean, so there is in the character of the
Fauna of the Italian lakes, and especially the presence of a Crab in the
Lake of Garda, some confirmation of such an idea. Further evidence,
however, is necessary before these interesting questions can be
definitely answered.
Lastly, some lakes and inland seas seem to be due to even greater
cosmical causes. Thus a line inclined ten degrees to the pole beginning
at Gibraltar would pass through a great chain of inland waters--the
Mediterranean, Black Sea, Caspian, Aral, Baikal, and back again through
the great American lakes.
But though many causes have contributed to the original formation and
direction of Valleys, their present condition is mainly due to the
action of water. When we contemplate such a valley, for example, as that
which is called _par excellence_ the "Valais," we can at first hardly
bring ourselves to realise this; but we can trace up valleys, from the
little water-course made by last night's rains up to the greatest
valleys of all.
These considerations, however, do not of course apply to such
depressions as those of the great oceans. These were probably formed
when the surface of the globe began to solidify, and, though with many
modifications, have maintained their main features ever since.
ON THE CONFIGURATION OF VALLEYS
The conditions thus briefly described repeat themselves in river after
river, valley after valley, and it adds, I think, very much to the
interest with which we regard them if, by studying the general causes to
which they are due, we can explain their origin, and thus to some extent
understand the story they have to tell us, and the history they record.
What, then, has that history been? The same valley may be of a very
different character, and due to very different causes, in different
parts of its course. Some valleys are due to folds (see Fig. 41) caused
by subterranean changes, but by far the greater number are, in their
present features, mainly the result of erosion. As soon as any tract of
land rose out of the sea, the rain which fell on the surface would
trickle downwards in a thousand rills, forming pools here and there (see
Fig. 37), and gradually collecting into larger and larger streams.
Wherever the slope was sufficient the water would begin cutting into the
soil and carrying it off to the sea. This action would be the same in
any case, but, of course, would differ in rapidity according to the
hardness of the ground. On the other hand, the character of the valley
would depend greatly on the character of the strata, being narrow where
they were hard and tough; broader, on the contrary, where they were
soft, so that they crumbled readily into the stream, or where they were
easily split by the weather. Gradually the stream would eat into its bed
until it reached a certain slope, the steepness of which would depend on
the volume of water. The erosive action would then cease, but the
weathering of the sides and consequent widening would continue, and the
river would wander from one part of its valley to another, spreading the
materials and forming a river plain. At length, as the rapidity still
further diminished, it would no longer have sufficient power even to
carry off the materials brought down. It would form, therefore, a cone
or delta, and instead of meandering, would tend to divide into different
branches. These three stages, we may call those of--
1. Deepening and widening;
2. Widening and levelling;
3. Filling up;
and every place in the second stage has passed through the first; every
one in the third has passed through the second.
A velocity of 6 inches per second will lift fine sand, 8 inches will
move sand as coarse as linseed, 12 inches will sweep along fine gravel,
24 inches will roll along rounded pebbles an inch diameter, and it
requires 3 feet per second at the bottom to sweep along angular stones
of the size of an egg.
When a river has so adjusted its slope that it neither deepens its bed
in the upper portion of its course, nor deposits materials, it is said
to have acquired its "regimen," and in such a case if the character of
the soil remains the same, the velocity must also be uniform. The
enlargement of the bed of a river is not, however, in proportion to the
increase of its waters as it approaches the sea. If, therefore, the
slope did not diminish, the regimen would be destroyed, and the river
would again commence to eat out its bed. Hence as rivers enlarge, the
slope diminishes, and consequently every river tends to assume some such
"regimen" as that shown in Fig. 46.
Now, suppose that the fall of the river is again increased, either by a
fresh elevation, or locally by the removal of a barrier. Then once more
the river regains its energy. Again it cuts into its old bed, deepening
the valley, and leaving the old plain as a terrace high above its new
course. In many valleys several such terraces may be seen, one above the
other. In the case of a river running in a transverse valley, that is to
say of a valley lying at right angles to the "strike" or direction of
the strata (such, for instance, as the Reuss), the water acts more
effectively than in longitudinal valleys running along the strike. Hence
the lateral valleys have been less deeply excavated than that of the
Reuss itself, and the streams from them enter the main valley by rapids
or cascades. Again, rivers running in transverse valleys cross rocks
which in many cases differ in hardness, and of course they cut down the
softer strata more rapidly than the harder ones; each ridge of harder
rock will therefore form a dam and give rise to a rapid, or cataract. We
often as we ascend a river, after a comparatively flat plain, find
ourselves in a narrow defile, down which the water rushes in an
impetuous torrent, but at the summit of which, to our surprise, we find
another broad flat valley.
Another lesson which we learn from the study of river valleys, is that,
just as geological structure was shown by Sir C. Lyell to be no evidence
of cataclysms, but the result of slow action; so also the excavation of
valleys is due mainly to the regular flow of rivers; and floods, though
their effects are more sudden and striking, have had, after all,
comparatively little part in the result.
The mouths of rivers fall into two principal classes. If we look at any
map we cannot but be struck by the fact that some rivers terminate in a
delta, some in an estuary. The Thames, for instance, ends in a noble
estuary, to which London owes much of its wealth and power. It is
obvious that the Thames could not have excavated this estuary while the
coast was at its present level. But we know that formerly the land stood
higher, that the German Ocean was once dry land, and the Thames, after
joining the Rhine, ran northwards, and fell eventually into the Arctic
Ocean. The estuary of the Thames, then, dates back to a period when the
south-east of England stood at a higher level than the present, and even
now the ancient course of the river can be traced by soundings under
what is now sea. The sites of present deltas, say of the Nile, were also
once under water, and have been gradually reclaimed by the deposits of
the river.
It would indeed be a great mistake to suppose that rivers always tend
to deepen their valleys. This is only the case when the slope exceeds a
certain angle. When the fall is but slight they tend on the contrary to
raise their beds by depositing sand and mud brought down from higher
levels. Hence in the lower part of their course many of the most
celebrated rivers--the Nile, the Po, the Mississippi, the Thames,
etc.--run upon embankments, partly of their own creation.
[Illustration: Fig. 48.--Diagrammatic section of a valley (exaggerated)
_R R_, rocky basis of valley; _A A_, sedimentary strata; _B_, ordinary
level of river; _C_, flood level.]
The Reno, the most dangerous of all the Apennine rivers, is in some
places as much as 30 feet above the adjoining country. Rivers under such
conditions, when not interfered with by Man, sooner or later break
through their banks, and leaving their former bed, take a new course
along the lowest part of their valley, which again they gradually raise
above the rest. Hence, unless they are kept in their own channels by
human agency, such rivers are continually changing their course.
If we imagine a river running down a regularly inclined plane in a more
or less straight line; any inequality or obstruction would produce an
oscillation, which when once started would go on increasing until the
force of gravity drawing the water in a straight line downwards equals
that of the force tending to divert its course. Hence the radius of the
curves will follow a regular law depending on the volume of water and
the angle of inclination of the bed. If the fall is 10 feet per mile and
the soil homogeneous, the curves would be so much extended that the
course would appear almost straight. With a fall of 1 foot per mile the
length of the curve is, according to Fergusson, about six times the
width of the river, so that a river 1000 feet wide would oscillate once
in 6000 feet. This is an important consideration, and much labour has
been lost in trying to prevent rivers from following their natural law
of oscillation. But rivers are very true to their own laws, and a change
at any part is continued both upwards and downwards, so that a new
oscillation in any place cuts its way through the whole plain of the
river both above and below.
The curves of the Mississippi are, for instance, for a considerable part
of its course so regular that they are said to have been used by the
Indians as a measure of distance.
If the country is flat a river gradually raises the level on each side,
the water which overflows during floods being retarded by reeds, bushes,
trees, and a thousand other obstacles, gradually deposits the solid
matter which it contains, and thus raising the surface, becomes at
length suspended, as it were, above the general level. When this
elevation has reached a certain point, the river during some flood
bursts its banks, and deserting its old bed takes a new course along the
lowest accessible level. This then it gradually fills up, and so on;
coming back from time to time if permitted, after a long cycle of
years, to its first course.
In evidence of the vast quantity of sediment which rivers deposit, I may
mention that the river-deposits at Calcutta are more than 400 feet in
thickness.
In addition to temporary "spates," due to heavy rain, most rivers are
fuller at one time of year than another, our rivers, for instance, in
winter, those of Switzerland, from the melting of the snow, in summer.
The Nile commences to rise towards the beginning of July; from August to
October it floods all the low lands, and early in November it sinks
again. At its greatest height the volume of water sometimes reaches
twenty times that when it is lowest, and yet perhaps not a drop of rain
may have fallen. Though we now know that this annual variation is due to
the melting of the snow and the fall of rain on the high lands of
Central Africa, still when we consider that the phenomenon has been
repeated annually for thousands of years it is impossible not to regard
it with wonder. In fact Egypt itself may be said to be the bed of the
Nile in flood time.
Some rivers, on the other hand, offer no such periodical differences.
The lower Rhone, for instance, below the junction with the Saône, is
nearly equal all through the year, and yet we know that the upper
portion is greatly derived from the melting of the Swiss snows. In this
case, however, while the Rhone itself is on this account highest in
summer and lowest in winter, the Saône, on the contrary, is swollen by
the winter's rain, and falls during the fine weather of summer. Hence
the two tend to counterbalance one another.
Periodical differences are of course comparatively easy to deal with. It
is very different with floods due to irregular rainfall. Here also,
however, the mere quantity of rain is by no means the only matter to be
considered. For instance a heavy rain in the watershed of the Seine,
unless very prolonged, causes less difference in the flow of the river,
say at Paris, than might at first have been expected, because the height
of the flood in the nearer affluents has passed down the river before
that from the more distant streams has arrived. The highest level is
reached when the rain in the districts drained by the various affluents
happens to be so timed that the different floods coincide in their
arrival at Paris.
FOOTNOTES:
[52] Darwin's _Voyage of a Naturalist_.
[53] _Geol. Jour._, 1863.
[54] Favre, _Rech. Geol. de la Savoie._
[55] _Growth and Structure of the Alps._
CHAPTER IX
THE SEA
There is a pleasure in the pathless woods,
There is a rapture on the lonely shore,
There is society, where none intrudes,
By the deep Sea, and music in its roar:
I love not Man the less, but Nature more,
From these our interviews, in which I steal
From all I may be, or have been before,
To mingle with the Universe, and feel
What I can ne'er express, yet cannot all conceal.
Roll on, thou deep and dark-blue Ocean--roll!
BYRON.
[Illustration: THE LAND'S END. _To face page 337._]
CHAPTER IX
THE SEA
When the glorious summer weather comes, when we feel that by a year's
honest work we have fairly won the prize of a good holiday, how we turn
instinctively to the Sea. We pine for the delicious smell of the sea
air, the murmur of the waves, the rushing sound of the pebbles on the
sloping shore, the cries of the sea-birds; and long to
Linger, where the pebble-paven shore,
Under the quick, faint kisses of the Sea,
Trembles and sparkles as with ecstasy.[56]
How beautiful the sea-coast is! At the foot of a cliff, perhaps of pure
white chalk, or rich red sandstone, or stern grey granite, lies the
shore of gravel or sand, with a few scattered plants of blue Sea Holly,
or yellow-flowered Horned Poppies, Sea-kale, Sea Convolvulus, Saltwort,
Artemisia, and Sea-grasses; the waves roll leisurely in one by one, and
as they reach the beach, each in turn rises up in an arch of clear,
cool, transparent, green water, tipped with white or faintly pinkish
foam, and breaks lovingly on the sands; while beyond lies the open Sea
sparkling in the sunshine.
... O pleasant Sea
Earth hath not a plain
So boundless or so beautiful as thine.[57]
The Sea is indeed at times overpoweringly beautiful. At morning and
evening a sheet of living silver or gold, at mid-day deep blue; even
Too deeply blue; too beautiful; too bright;
Oh, that the shadow of a cloud might rest
Somewhere upon the splendour of thy breast
In momentary gloom.[58]
There are few prettier sights than the beach at a seaside town on a fine
summer's day; the waves sparkling in the sunshine, the water and sky
each bluer than the other, while the sea seems as if it had nothing to
do but to laugh and play with the children on the sands; the children
perseveringly making castles with spades and pails, which the waves then
run up to and wash away, over and over and over again, until evening
comes and the children go home, when the Sea makes everything smooth and
ready for the next day's play.
Many are satisfied to admire the Sea from shore, others more ambitious
or more free prefer a cruise. They feel with Tennyson's voyager:
We left behind the painted buoy
That tosses at the harbour-mouth;
And madly danced our hearts with joy,
As fast we fleeted to the South:
How fresh was every sight and sound
On open main or winding shore!
We knew the merry world was round,
And we might sail for evermore.
Many appreciate both. The long roll of the Mediterranean on a fine day
(and I suppose even more of the Atlantic, which I have never enjoyed),
far from land in a good ship, and with kind friends, is a joy never to
be forgotten.
To the Gulf Stream and the Atlantic Ocean Northern Europe owes its mild
climate. The same latitudes on the other side of the Atlantic are much
colder. To find the same average temperature in the United States we
must go far to the south. Immediately opposite us lies Labrador, with an
average temperature the same as that of Greenland; a coast almost
destitute of vegetation, a country of snow and ice, whose principal
wealth consists in its furs, and a scattered population, mainly composed
of Indians and Esquimaux. But the Atlantic would not alone produce so
great an effect. We owe our mild and genial climate mainly to the Gulf
Stream--a river in the ocean, twenty million times as great as the
Rhone--the greatest, and for us the most important, river in the world,
which brings to our shores the sunshine of the West Indies.
The Sea is outside time. A thousand, ten thousand, or a million years
ago it must have looked just as it does now, and as it will ages hence.
With the land this is not so. The mountains and hills, rivers and
valleys, animals and plants are continually changing: but the Sea is
always the same,
Steadfast, serene, immovable, the same
Year after year.
Directly we see the coast, or even a ship, the case is altered. Boats
may remain the same for centuries, but ships are continually being
changed. The wooden walls of old England are things of the past, and the
ironclads of to-day will soon be themselves improved off the face of the
ocean.
The great characteristic of Lakes is peace, that of the Sea is energy,
somewhat restless, perhaps, but still movement without fatigue.
The Earth lies quiet like a child asleep,
The deep heart of the Heaven is calm and still,
Must thou alone a restless vigil keep,
And with thy sobbing all the silence fill.[59]
A Lake in a storm rather gives us the impression of a beautiful Water
Spirit tormented by some Evil Demon; but a storm at Sea is one of the
grandest manifestations of Nature.
Yet more; the billows and the depths have more;
High hearts and brave are gathered to thy breast;
They hear not now the booming waters roar,
The battle thunders will not break their rest.
Keep thy red gold and gems, thou stormy grave;
Give back the true and brave.[60]
The most vivid description of a storm at sea is, I think, the following
passage from Ruskin's _Modern Painters_:
"Few people, comparatively, have ever seen the effect on the
sea of a powerful gale continued without intermission for three
or four days and nights; and to those who have not, I believe
it must be unimaginable, not from the mere force or size of the
surge, but from the complete annihilation of the limit between
sea and air. The water from its prolonged agitation is beaten,
not into mere creaming foam, but into masses of accumulated
yeast, which hangs in ropes and wreaths from wave to wave, and,
where one curls over to break, form a festoon like a drapery
from its edge; these are taken up by the wind, not in
dissipating dust, but bodily, in writhing, hanging, coiling
masses, which make the air white and thick as with snow, only
the flakes are a foot or two long each: the surges themselves
are full of foam in their very bodies underneath, making them
white all through, as the water is under a great cataract; and
their masses, being thus half water and half air, are torn to
pieces by the wind whenever they rise, and carried away in
roaring smoke, which chokes and strangles like actual water.
Add to this, that when the air has been exhausted of its
moisture by long rain, the spray of the sea is caught by it as
described above, and covers its surface not merely with the
smoke of finely divided water, but with boiling mist; imagine
also the low rain-clouds brought down to the very level of the
sea, as I have often seen them, whirling and flying in rags and
fragments from wave to wave; and finally, conceive the surges
themselves in their utmost pitch of power, velocity, vastness,
and madness, lifting themselves in precipices and peaks,
furrowed with their whirl of ascent, through all this chaos,
and you will understand that there is indeed no distinction
left between the sea and air; that no object, nor horizon, nor
any landmark or natural evidence of position is left; and the
heaven is all spray, and the ocean all cloud, and that you can
see no further in any direction than you see through a
cataract."
SEA LIFE
The Sea teems with life. The Great Sea Serpent is, indeed, as much a
myth as the Kraken of Pontoppidan, but other monsters, scarcely less
marvellous, are actual realities. The Giant Cuttle Fish of Newfoundland,
though the body is comparatively small, may measure 60 feet from the tip
of one arm to that of another. The Whalebone Whale reaches a length of
over 70 feet, but is timid and inoffensive. The Cachalot or Sperm Whale,
which almost alone among animals roams over the whole ocean, is as
large, and much more formidable. It is armed with powerful teeth, and is
said to feed mainly on Cuttle Fish, but sometimes on true fishes, or
even Seals. When wounded it often attacks boats, and its companions do
not hesitate to come to the rescue. In one case, indeed, an American
ship was actually attacked, stove in, and sunk by a gigantic male
Cachalot.
The Great Roqual is still more formidable, and has been said to attain a
length of 120 feet, but this is probably an exaggeration. So far as we
know, the largest species of all is Simmond's Whale, which reaches a
maximum of 85 to 90 feet.
In former times Whales were frequent on our coasts, so that, as Bishop
Pontoppidan said, the sea sometimes appeared as if covered with smoking
chimneys, but they have been gradually driven further and further north,
and are still becoming rarer. As they retreated man followed, and to
them we owe much of our progress in geography. Is it not, however, worth
considering whether they might not also be allowed a "truce of God,"
whether some part of the ocean might not be allotted to them where they
might be allowed to breed in peace? As a mere mercantile arrangement the
maritime nations would probably find this very remunerative. The
reckless slaughter of Whales, Sea Elephants, Seals, and other marine
animals is a sad blot, not only on the character, but on the common
sense, of man.
The monsters of the ocean require large quantities of food, but they are
supplied abundantly. Scoresby mentions cases in which the sea was for
miles tinged of an olive green by a species of Medusa. He calculates
that in a cubic mile there must have been 23,888,000,000,000,000, and
though no doubt the living mass did not reach to any great depth, still,
as he sailed through water thus discoloured for many miles, the number
must have been almost incalculable.
This is, moreover, no rare or exceptional case. Navigators often sail
for leagues through shoals of creatures, which alter the whole colour of
the sea, and actually change it, as Reclus says, into "une masse
animée."
Still, though the whole ocean teems with life, both animals and plants
are most abundant near the coast. Air-breathing animals, whether mammals
or insects, are naturally not well adapted to live far from dry land.
Even Seals, though some of them make remarkable migrations, remain
habitually near the shore. Whales alone are specially modified so as to
make the wide ocean their home. Of birds the greatest wanderer is the
Albatross, which has such powers of flight that it is said even to sleep
on the wing.
Many Pelagic animals--Jelly-fishes, Molluscs, Cuttle-fishes, Worms,
Crustacea, and some true fishes--are remarkable for having become
perfectly transparent; their shells, muscles, and even their blood have
lost all colour, or even undergone the further modification of having
become blue, often with beautiful opalescent reflections. This obviously
renders them less visible, and less liable to danger.
The sea-shore, wherever a firm hold can be obtained, is covered with
Sea-weeds, which fall roughly into two main divisions, olive-green and
red, the latter colour having a special relation to light. These
Sea-weeds afford food and shelter to innumerable animals.
The clear rocky pools left by the retiring tide are richly clothed with
green sea-weeds, while against the sides are tufts of beautiful filmy
red algæ, interspersed with Sea-anemones,--white, creamy, pink, yellow,
purple, with a coronet of blue beads, and of many mixed colours;
Sponges, Corallines, Starfish, Limpets, Barnacles, and other shell-fish;
feathery Zoophytes and Annelides expand their pink or white disks, while
here and there a Crab scuttles across; little Fish or Shrimps timidly
come out from crevices in the rocks, or from among the fronds of the
sea-weeds, or hastily dart from shelter to shelter; each little pool is,
in fact, a miniature ocean in itself, and the longer one looks the more
and more one will see.
The dark green and brown sea-weeds do not live beyond a few--say about
15--fathoms in depth. Below them occur delicate scarlet species, with
Corallines and a different set of shells, Sea-urchins, etc. Down to
about 100 fathoms the animals and plants are still numerous and varied.
But they gradually diminish in numbers, and are replaced by new forms.
To appreciate fully the extreme loveliness of marine animals they must
be seen alive. "A tuft of Sertularia, laden with white, or brilliantly
tinted Polypites," says Hincks, "like blossoms on some tropical tree, is
a perfect marvel of beauty. The unfolding of a mass of Plumularia, taken
from amongst the miscellaneous contents of the dredge, and thrown into a
bottle of clear sea-water, is a sight which, once seen, no dredger will
forget. A tree of Campanularia, when each one of its thousand
transparent calycles--itself a study of form--is crowned by a circlet of
beaded arms, drooping over its margin like the petals of a flower,
offers a rare combination of the elements of beauty.
"The rocky wall of some deep tidal pool, thickly studded with the long
and slender stems of Tubularia, surmounted by the bright rose-coloured
heads, is like the gay parterre of a garden. Equally beautiful is the
dense growth of Campanularia, covering (as I have seen it in Plymouth
Sound) large tracts of the rock, its delicate shoots swaying to and fro
with each movement of the water, like trees in a storm, or the colony of
Obelia on the waving frond of the tangle looking almost ethereal in its
grace, transparency, and delicacy, as seen against the coarse dark
surface that supports it."
Few things are more beautiful than to look down from a boat into
transparent water. At the bottom wave graceful sea-weeds, brown, green,
or rose-coloured, and of most varied forms; on them and on the sands or
rocks rest starfishes, mollusca, crustaceans, Sea-anemones, and
innumerable other animals of strange forms and varied colours; in the
clear water float or dart about endless creatures; true fishes, many of
them brilliantly coloured; Cuttle-fishes like bad dreams; Lobsters and
Crabs with graceful, transparent Shrimps; Worms swimming about like
living ribbons, some with thousands of coloured eyes, and Medusæ like
living glass of the richest and softest hues, or glittering in the
sunshine with all the colours of the rainbow.
And on calm, cool nights how often have I stood on the deck of a ship
watching with wonder and awe the stars overhead, and the sea-fire below,
especially in the foaming, silvery wake of the vessel, where often
suddenly appear globes of soft and lambent light, given out perhaps
from the surface of some large Medusa.
"A beautiful white cloud of foam," says Coleridge, "at momently
intervals coursed by the side of the vessel with a roar, and little
stars of flame danced and sparkled and went out in it; and every now and
then light detachments of this white cloud-like foam darted off from the
vessel's side, each with its own small constellation, over the sea, and
scoured out of sight like a Tartar troop over a wilderness."
Fish also are sometimes luminous. The Sun-fish has been seen to glow
like a white-hot cannon-ball, and in one species of Shark (Squalus
fulgens) the whole surface sometimes gives out a greenish lurid light
which makes it a most ghastly object, like some great ravenous spectre.
THE OCEAN DEPTHS
The Land bears a rich harvest of life, but only at the surface. The
Ocean, on the contrary, though more richly peopled in its upper layers,
which swarm with such innumerable multitudes of living creatures that
they are, so to say, almost themselves alive--teems throughout with
living beings.
The deepest abysses have a fauna of their own, which makes up for the
comparative scantiness of its numbers, by the peculiarity and interest
of their forms and organisation. The middle waters are the home of
various Fishes, Medusæ, and animalcules, while the upper layers swarm
with an inexhaustible variety of living creatures.
It used to be supposed that the depths of the Ocean were destitute of
animal life, but recent researches, and especially those made during our
great national expedition in the "Challenger," have shown that this is
not the case, but that the Ocean depths have a wonderful and peculiar
life of their own. Fish have been dredged up even from a depth of 2750
fathoms.
The conditions of life in the Ocean depths are very peculiar. The light
of the sun cannot penetrate beyond about two hundred fathoms; deeper
than this complete darkness prevails. Hence in many species the eyes
have more or less completely disappeared.
Sir Wyville Thomson mentions a kind of Crab (Ethusa granulata), which
when living near the surface has well developed eyes; in deeper water,
100 to 400 fathoms, eyestalks are present, but the animal is apparently
blind, the eyes themselves being absent; while in specimens from a depth
of 500-700 fathoms the eyestalks themselves have lost their special
character, and have become fixed, their terminations being combined into
a strong, pointed beak.
In other deep sea creatures, on the contrary, the eyes gradually become
more and more developed, so that while in some species the eyes
gradually dwindle, in others they become unusually large.
Many of the latter species may be said to be a light to themselves,
being provided with a larger or smaller number of curious luminous
organs. The deep sea fish are either silvery, pink, or in many cases
black, sometimes relieved with scarlet, and when the luminous organs
flash out must present a very remarkable appearance.
We have still much to learn as to the structure and functions of these
organs, but there are cases in which their use can be surmised with some
probability. The light is evidently under the will of the fish.[61] It
is easy to imagine a Photichthys (Light Fish) swimming in the black
depths of the Ocean, suddenly flashing out light from its luminous
organs, and thus bringing into view any prey which may be near; while,
if danger is disclosed, the light is again at once extinguished. It may
be observed that the largest of these organs is in this species situated
just under the eye, so that the fish is actually provided with a bull's
eye lantern. In other cases the light may rather serve as a defence,
some having, as, for instance, in the genus Scopelus, a pair of large
ones in the tail, so that "a strong ray of light shot forth from the
stern-chaser may dazzle and frighten an enemy."
In other cases they appear to serve as lures. The "Sea-devil" or
"Angler" of our coasts has on its head three long, very flexible,
reddish filaments, while all round its head are fringed appendages,
closely resembling fronds of sea-weed. The fish conceals itself at the
bottom, in the sand or among sea-weed, and dangles the long filaments in
front of its mouth. Little fishes, taking these filaments for worms,
unsuspectingly approach, and thus fall victims.
Several species of the same family live at great depths, and have very
similar habits. A mere red filament would be invisible in the dark and
therefore useless. They have, however, developed a luminous organ, a
living "glow-lamp," at the end of the filament, which doubtless proves a
very effective lure.
In the great depths, however, fish are comparatively rare. Nor are
Molluscs much more abundant. Sea-urchins, Sea Slugs, and Starfish are
more numerous, and on one occasion 20,000 specimens of an Echinus were
brought up at a single haul. True corals are rare, nor are Hydrozoa
frequent, though a giant species, allied to the little Hydra of our
ponds but upwards of 6 feet in height, has more than once been met
with. Sponges are numerous, and often very beautiful. The now well known
Euplectella, "Venus's Flower-basket," resembles an exquisitely delicate
fabric woven in spun silk; it is in the form of a gracefully curved
tube, expanding slightly upwards and ending in an elegant frill. The
wall is formed of parallel bands of glassy siliceous fibres, crossed by
others at right angles, so as to form a square meshed net. These sponges
are anchored on the fine ooze by wisps of glassy filaments, which often
attain a considerable length. Many of these beautiful organisms,
moreover, glow when alive with a soft diffused light, flickering and
sparkling at every touch. What would one not give to be able to wander a
while in these wonderful regions!
It is curious that no plants, so far as we know, grow in the depths of
the Ocean, or, indeed, as far as our present information goes, at a
greater depth than about 100 fathoms.
As regards the nature of the bottom itself, it is in the neighbourhood
of land mainly composed of materials, brought down by rivers or washed
from the shore, coarser near the coast, and tending to become finer and
finer as the distance increases and the water deepens. The bed of the
Atlantic from 400 to 2000 fathoms is covered with an ooze, or very fine
chalky deposit, consisting to a great extent of minute and more or less
broken shells, especially those of Globigerina. At still greater depths
the carbonate of lime gradually disappears, and the bottom consists of
fine red clay, with numerous minute particles, some of volcanic, some of
meteoric, origin, fragments of shooting stars, over 100,000,000 of which
are said to strike the surface of our earth every year. How slow the
process of deposition must be, may be inferred from the fact that the
trawl sometimes brings up many teeth of Sharks and ear-bones of Whales
(in one case no less than 600 teeth and 100 ear-bones), often
semi-fossil, and which from their great density had remained intact for
ages, long after all the softer parts had perished and disappeared.
The greatest depth of the Ocean appears to coincide roughly with the
greatest height of the mountains. There are indeed cases recorded in
which it is said that "no bottom" was found even at 39,000 feet. It is,
however, by no means easy to sound at such great depths, and it is now
generally considered that these earlier observations are untrustworthy.
The greatest depth known in the Atlantic is 3875 fathoms--a little to
the north of the Virgin Islands, but the soundings as yet made in the
deeper parts of the Ocean are few in number, and it is not to be
supposed that the greatest depth has yet been ascertained.
CORAL ISLANDS
In many parts of the world the geography itself has been modified by the
enormous development of animal life. Most islands fall into one of three
principal categories:
Firstly, Those which are in reality a part of the continent near which
they lie, being connected by comparatively shallow water, and standing
to the continent somewhat in the relation of planets to the sun; as,
for instance, the Cape de Verde Islands to Africa, Ceylon to India, or
Tasmania to Australia.
Secondly, Volcanic islands; and
Thirdly, Those which owe their origin to the growth of Coral reefs.
[Illustration: Fig. 49.--Whitsunday Island.]
Coral islands are especially numerous in the Indian and Pacific Oceans,
where there are innumerable islets, in the form of rings, or which
together form rings, the rings themselves being sometimes made up of
ringlets. These "atolls" contain a circular basin of yellowish green,
clear, shallow water, while outside is the dark blue deep water of the
Ocean. The islands themselves are quite low, with a beach of white sand
rising but a few feet above the level of the water, and bear generally
groups of tufted Cocoa Palms.
It used to be supposed that these were the summits of submarine
volcanoes on which the coral had grown. But as the reef-making coral
does not live at greater depths than about twenty-five fathoms, the
immense number of these reefs formed an almost insuperable objection to
this theory. The Laccadives and Maldives for instance--meaning literally
the "lac of or 100,000 islands," and the "thousand islands"--are a
series of such atolls, and it was impossible to imagine so great a
number of craters, all so nearly of the same altitude.
In shallow tracts of sea, coral reefs no doubt tend to assume the
well-known circular form, but the difficulty was to account for the
numerous atolls which rise to the surface from the abysses of the ocean,
while the coral-forming zoophytes can only live near the surface.
Darwin showed that so far from the ring of corals resting on a
corresponding ridge of rocks, the lagoons, on the contrary, now occupy
the place which was once the highest land. He pointed out that some
lagoons, as for instance that of Vanikoro, contain an island in the
middle; while other islands, such as Tahiti, are surrounded by a margin
of smooth water separated from the ocean by a coral reef. Now if we
suppose that Tahiti were to sink slowly it would gradually approximate
to the condition of Vanikoro; and if Vanikoro gradually sank, the
central island would disappear, while on the contrary the growth of the
coral might neutralise the subsidence of the reef, so that we should
have simply an atoll with its lagoon. The same considerations explain
the origin of the "barrier reefs," such as that which runs for nearly a
thousand miles, along the north-east coast of Australia. Thus Darwin's
theory explains the form and the approximate identity of altitude of
these coral islands. But it does more than this, because it shows that
there are great areas in process of subsidence, which though slow, is of
great importance in physical geography.
The lagoon islands have received much attention; which "is not
surprising, for every one must be struck with astonishment, when he
first beholds one of these vast rings of coral-rock, often many leagues
in diameter, here and there surmounted by a low verdant island with
dazzling white shores, bathed on the outside by the foaming breakers of
the ocean, and on the inside surrounding a calm expanse of water, which,
from reflection is generally of a bright but pale green colour. The
naturalist will feel this astonishment more deeply after having examined
the soft and almost gelatinous bodies of these apparently insignificant
coral-polypifers, and when he knows that the solid reef increases only
on the outer edge, which day and night is lashed by the breakers of an
ocean never at rest. Well did François Pyrard de Laval, in the year 1605
exclaim, 'C'est une merveille de voir chacun de ces atollons, environné
d'un grand banc de pierre tout autour, n'y ayant point d'artifice
humain.'"[62]
Of the enchanting beauty of the coral beds themselves we are assured
that language conveys no adequate idea. "There were corals," says Prof.
Ball, "which, in their living state, are of many shades of fawn, buff,
pink, and blue, while some were tipped with a magenta-like bloom.
Sponges which looked as hard as stone spread over wide areas, while
sprays of coralline added their graceful forms to the picture. Through
the vistas so formed, golden-banded and metallic-blue fish meandered,
while on the patches of sand here and there Holothurias and various
mollusca and crustaceans might be seen slowly crawling."
Abercromby also gives a very graphic description of a Coral reef. "As we
approached," he says, "the roaring surf on the outside, fingery lumps of
beautiful live coral began to appear of the palest lavender-blue colour;
and when at last we were almost within the spray, the whole floor was
one mass of living branches of coral.
"But it is only when venturing as far as is prudent into the water, over
the outward edge of the great sea wall, that the true character of the
reef and all the beauties of the ocean can be really seen. After
walking over a flat uninteresting tract of nearly bare rock, you look
down and see a steep irregular wall, expanding deeper into the ocean
than the eye can follow, and broken into lovely grottoes and holes and
canals, through which small resplendent fish of the brightest blue or
gold flit fitfully between the lumps of coral. The sides of these
natural grottoes are entirely covered with endless forms of
tender-coloured coral, but all beautiful, and all more or less of the
fingery or branching species, known as madrepores. It is really
impossible to draw or describe the sight, which must be taken with all
its surroundings as adjuncts."[63]
The vegetation of these fairy lands is also very lovely; the Coral tree
(Erythrina) with light green leaves and bunches of scarlet blossoms, the
Cocoa-nut always beautiful, the breadfruit, the graceful tree ferns, the
Barringtonia, with large pink and white flowers, several species of
Convolvulus, and many others unknown to us even by name.
THE SOUTHERN SKIES
In considering these exquisite scenes, the beauty of the Southern skies
must not be omitted. "From the time we entered the torrid zone," says
Humboldt, "we were never wearied with admiring, every night, the beauty
of the southern sky, which, as we advanced towards the south, opened new
constellations to our view. We feel an indescribable sensation, when, on
approaching the equator, and particularly on passing from one hemisphere
to the other, we see those stars which we have contemplated from our
infancy, progressively sink, and finally disappear. Nothing awakens in
the traveller a livelier remembrance of the immense distance by which he
is separated from his country, than the aspect of an unknown firmament.
The grouping of the stars of the first magnitude, some scattered nebulæ
rivalling in splendour the milky way, and tracts of space remarkable for
their extreme blackness, give a particular physiognomy to the southern
sky. This sight fills with admiration even those, who, uninstructed in
the branches of accurate science, feel the same emotions of delight in
the contemplation of the heavenly vault, as in the view of a beautiful
landscape, or a majestic river. A traveller has no need of being a
botanist to recognise the torrid zone on the mere aspect of its
vegetation; and, without having acquired any notion of astronomy, he
feels he is not in Europe, when he sees the immense constellation of the
Ship, or the phosphorescent clouds of Magellan, arise on the horizon.
The heaven and the earth, in the equinoctial regions, assume an exotic
character."
"The sunsets in the Eastern Archipelago," says H. O. Forbes,[64] "were
scenes to be remembered for a lifetime. The tall cones of Sibissie and
Krakatoa rose dark purple out of an unruffled golden sea, which
stretched away to the south-west, where the sun went down; over the
horizon gray fleecy clouds lay in banks and streaks, above them pale
blue lanes of sky, alternating with orange bands, which higher up gave
place to an expanse of red stretching round the whole heavens.
Gradually as the sun retreated deeper and deeper, the sky became a
marvellous golden curtain, in front of which the gray clouds coiled
themselves into weird forms before dissolving into space...."
THE POLES
The Arctic and Antarctic regions have always exercised a peculiar
fascination over the human mind. Until now every attempt to reach the
North Pole has failed, and the South has proved even more inaccessible.
In the north, Parry all but reached lat. 83; in the south no one has
penetrated beyond lat. 71.11. And yet, while no one can say what there
may be round the North Pole, and some still imagine that open water
might be found there, we can picture to ourselves the extreme South with
somewhat more confidence.
Whenever ships have sailed southwards, except at a few places where land
has been met with, they have come at last to a wall of ice, from fifty
to four hundred feet high. In those regions it snows, if not
incessantly, at least very frequently, and the snow melts but little. As
far as the eye can reach nothing is to be seen but snow. Now this snow
must gradually accumulate, and solidify into ice, until it attains such
a slope that it will move forward as a glacier. The enormous Icebergs of
the Southern Ocean, moreover, show that it does so, and that the snow of
the extreme south, after condensing into ice, moves slowly outward and
at length forms a wall of ice, from which Icebergs, from time to time,
break away. We do not exactly know what, under such circumstances, the
slope would be; but Mr. Croll points out that if we take it at only half
a degree, and this seems quite a minimum, the Ice cap at the South Pole
must be no less than twelve miles in thickness. It is indeed probably
even more, for some of the Southern tabular icebergs attain a height of
eight hundred, or even a thousand feet above water, indicating a total
thickness of the ice sheet even at the edge, of over a mile.
Sir James Ross mentions that--"Whilst measuring some angles for the
survey near Mount Lubbock an island suddenly appeared, which he was
quite sure was not to be seen two or three hours previously. He was much
astonished, but it eventually turned out to be a large iceberg, which
had turned over, and so exposed a new surface covered with earth and
stones."
The condition of the Arctic regions is quite different. There is much
more land, and no such enormous solid cap of ice. Spitzbergen, the land
of "pointed mountains," is said to be very beautiful. Lord Dufferin
describes his first view of it as "a forest of thin lilac peaks, so
faint, so pale, that had it not been for the gem-like distinctness of
their outline one could have deemed them as unsubstantial as the spires
of Fairyland."
It is, however, very desolate; scarcely any vegetation excepting a dark
moss, and even this goes but a little way up the mountain side. Scoresby
ascended one of the hills near Horn Sound, and describes the view as
"most extensive and grand. A fine sheltered bay was seen to the east of
us, an arm of the same on the north-east, and the sea, whose glassy
surface was unruffled by a breeze, formed an immense expanse on the
west; the glaciers, rearing their proud crests almost to the tops of
mountains between which they were lodged, and defying the power of the
solar beams, were scattered in various directions about the sea-coast
and in the adjoining bays. Beds of snow and ice filling extensive
hollows, and giving an enamelled coat to adjoining valleys, one of
which, commencing at the foot of the mountain where we stood, extended
in a continual line towards the north, as far as the eye could
reach--mountain rising above mountain, until by distance they dwindled
into insignificance, the whole contrasted by a cloudless canopy of
deepest azure, and enlightened by the rays of a blazing sun, and the
effect, aided by a feeling of danger, seated as we were on the pinnacle
of a rock almost surrounded by tremendous precipices--all united to
constitute a picture singularly sublime."
One of the glaciers of Spitzbergen is 11 miles in breadth when it
reaches the sea-coast, the highest part of the precipitous front
adjoining the sea being over 400 feet, and it extends far upwards
towards the summit of the mountain. The surface forms an inclined plane
of smooth unsullied snow, the beauty and brightness of which render it a
conspicuous landmark on that inhospitable shore. From the perpendicular
face great masses of ice from time to time break away,
Whose blocks of sapphire seem to mortal eye
Hewn from cærulean quarries of the sky.[65]
Field ice is comparatively flat, though it may be piled up perhaps as
much as 50 feet. It is from glaciers that true icebergs, the beauty and
brilliance of which Arctic travellers are never tired of describing,
take their origin.
The attempts to reach the North Pole have cost many valuable lives;
Willoughby and Hudson, Behring and Franklin, and many other brave
mariners; but yet there are few expeditions more popular than those to
"the Arctic," and we cannot but hope that it is still reserved for the
British Navy after so many gallant attempts at length to reach the North
Pole.
FOOTNOTES:
[56] Shelley.
[57] Campbell.
[58] Holmes.
[59] Bell.
[60] Hemans.
[61] Gunther, _History of Fishes_.
[62] Darwin, _Coral Reefs_.
[63] Abercromby, _Seas and Skies in many Latitudes_.
[64] _A Naturalist's Wanderings in the Eastern Archipelago._
[65] Montgomery.
CHAPTER X
THE STARRY HEAVENS
A man can hardly lift up his eyes towards the heavens without
wonder and veneration, to see so many millions of radiant
lights, and to observe their courses and revolutions, even
without any respect to the common good of the
Universe.--SENECA.
CHAPTER X
THE STARRY HEAVENS
Many years ago I paid a visit to Naples, and ascended Vesuvius to see
the sun rise from the top of the mountain. We went up to the Observatory
in the evening and spent the night outside. The sky was clear; at our
feet was the sea, and round the bay the lights of Naples formed a lovely
semicircle. Far more beautiful, however, were the moon and the stars
overhead; the moon throwing a silver path over the water, and the stars
shining in that clear atmosphere with a brilliance which I shall never
forget.
For ages and ages past men have admired the same glorious spectacle, and
yet neither the imagination of Man nor the genius of Poetry had risen to
the truer and grander conceptions of the Heavens for which we are
indebted to astronomical Science. The mechanical contrivances by which
it was attempted to explain the movements of the heavenly bodies were
clumsy and prosaic when compared with the great discovery of Newton.
Ruskin is unjust I think when he says "Science teaches us that the
clouds are a sleety mist; Art, that they are a golden throne." I should
be the last to disparage the debt we owe to Art, but for our knowledge,
and even more, for our appreciation, feeble as even yet it is, of the
overwhelming grandeur of the Heavens, we are mainly indebted to Science.
There is scarcely a form which the fancy of Man has not sometimes
detected in the clouds,--chains of mountains, splendid cities, storms at
sea, flights of birds, groups of animals, monsters of all kinds,--and
our superstitious ancestors often terrified themselves by fantastic
visions of arms and warriors and battles which they regarded as portents
of coming calamities. There is hardly a day on which Clouds do not
delight and surprise us by their forms and colours. They belong,
however, to our Earth, and I must now pass on to the heavenly bodies.
[Illustration: THE MOON.
_To face page 377._]
THE MOON
The Moon is the nearest, and being the nearest, appears to us, with the
single exception of the Sun, the largest, although it is in reality one
of the smallest, of the heavenly bodies. Just as the Earth goes round
the Sun, and the period of revolution constitutes a year, so the Moon
goes round the Earth approximately in a period of one month. But while
we turn on our axis every twenty-four hours, thus causing the
alternation of light and darkness--day and night--the Moon takes a month
to revolve on hers, so that she always presents the same, or very nearly
the same, surface to us.
Seeing her as we do, not like the Sun and Stars, by light of her own,
but by the reflected light of the Sun, her form appears to change,
because the side upon which the Sun shines is not always that which we
see. Hence the "phases" of the Moon, which add so much to her beauty
and interest.
Who is there who has not watched them with admiration? "We first see her
as an exquisite crescent of pale light in the western sky after sunset.
Night after night she moves further and further to the east, until she
becomes full, and rises about the same time that the Sun sets. From the
time of full moon the disc of light begins to diminish, until the last
quarter is reached. Then it is that the Moon is seen high in the heavens
in the morning. As the days pass by, the crescent shape is again
assumed. The crescent wanes thinner and thinner as the Moon draws closer
to the Sun. Finally, she becomes lost in the overpowering light of the
Sun, again to emerge as the new moon, and again to go through the same
cycle of changes."[66]
But although she is so small the Moon is not only, next to the Sun, by
far the most beautiful, but also for us the most important, of the
heavenly bodies. Her attraction, aided by that of the Sun, causes the
tides, which are of such essential service to navigation. They carry
our vessels in and out of port, and, indeed, but for them many of our
ports would themselves cease to exist, being silted up by the rivers
running into them. The Moon is also of invaluable service to sailors by
enabling them to determine where they are, and guiding them over the
pathless waters.
The geography of the Moon, so far as concerns the side turned towards
us, has been carefully mapped and studied, and may almost be said to be
as well known as that of our own earth. The scenery is in a high degree
weird and rugged; it is a great wilderness of extinct volcanoes, and,
seen with even a very moderate telescope, is a most beautiful object.
The mountains are of great size. Our loftiest mountain, Mount Everest,
is generally stated as about 29,000 feet in height. The mountains of the
Moon reach an altitude of over 42,000, but this reckons to the lowest
depression, and it must be remembered that we reckon the height of
mountains to the sea level only. Several of the craters on the Moon have
a diameter of 40 or 50--one of them even as much as 78--miles. Many
also have central cones, closely resembling those in our own volcanic
regions. In some cases the craters are filled nearly to the brim with
lava. The volcanoes seem, however, to be all extinct; and there is not a
single case in which we have conclusive evidence of any change in a
lunar mountain.
[Illustration: Fig. 50.--A group of Lunar Volcanoes.]
The Moon, being so much smaller than the earth, cooled, of course, much
more rapidly, and it is probable that these mountains are millions of
years old--much older than many of our mountain chains. Yet no one can
look at a map of the Moon without being struck with the very rugged
character of its mountain scenery. This is mainly due to the absence of
air and water. To these two mighty agencies, not merely "the
cloud-capped towers, the gorgeous palaces, the solemn temples," but the
very mountains themselves, are inevitable victims. Not merely storms and
hurricanes, but every gentle shower, every fall of snow, tends to soften
our scenery and lower the mountain peaks. These agencies are absent from
the Moon, and the mountains stand to-day just as they were formed
millions of years ago.
But though we find on our own globe (see, for instance, Fig. 21)
volcanic regions closely resembling those of the Moon, there are other
phenomena on the Moon's surface for which our earth presents as yet no
explanation. From Tycho, for instance, a crater 17,000 feet high and 50
miles across, a number of rays or streaks diverge, which for hundreds,
or in some cases two or three thousand, miles pass straight across
plains, craters, and mountains. The true nature of these streaks is not
yet understood.
THE SUN
The Sun is more than 400 times as distant as the Moon; a mighty glowing
globe, infinitely hotter than any earthly fiery furnace, 300,000 times
as heavy, and 1,000,000 times as large as the earth. Its diameter is
865,000 miles, and it revolves on its axis in between 25 and 26 days.
Its distance is 92,500,000 miles. And yet it is only a star, and by no
means one of the first magnitude.
The surface of the Sun is the seat of violent storms and tempests. From
it gigantic flames, consisting mainly of hydrogen, flicker and leap.
Professor Young describes one as being, when first observed, 40,000
miles high. Suddenly it became very brilliant, and in half an hour
sprang up 40,000 more. For another hour it soared higher and higher,
reaching finally an elevation of no less than 350,000 miles, after which
it slowly faded away, and in a couple of hours had entirely disappeared.
This was no doubt an exceptional case, but a height of 100,000 miles is
not unusual, and the velocity frequently reaches 100 miles in a second.
The proverbial spots on the Sun in many respects resemble the
appearances which would be presented if a comparatively dark central
mass was here and there exposed by apertures through the more brilliant
outer gases, but their true nature is still a matter of discussion.
During total eclipses it is seen that the Sun is surrounded by a
"corona," or aureola of light, consisting of radiant filaments, beams,
and sheets of light, which radiate in all directions, and the true
nature of which is still doubtful.
Another stupendous problem connected with the Sun is the fact that, as
geology teaches us, it has given off nearly the same quantity of light
and heat for millions of years. How has this come to pass? Certainly not
by any process of burning such as we are familiar with. Indeed, if the
heat of the Sun were due to combustion it would be burnt up in 6000
years. It has been suggested that the meteors, which fall in showers on
to the Sun, replace the heat which is emitted. To some slight extent
perhaps they do so, but the main cause seems to be the slow condensation
of the Sun itself. Mathematicians tell us that a contraction of about
220 feet a year would account for the whole heat emitted, and as the
present diameter of the Sun is about 860,000 miles, the potential store
of heat is still enormous.
To the Sun we owe our light and heat; it is not only the centre of our
planetary system, it is the source and ruler of our lives. It draws up
water from the ocean, and pours it down in rain to fill the rivers and
refresh the plants; it raises the winds, which purify the air and waft
our ships over the seas; it draws our carriages and drives our
steam-engines, for coal is but the heat of former ages stored up for our
use; animals live and move by the Sun's warmth; it inspires the song of
birds, paints the flowers, and ripens the fruit. Through it the trees
grow. For the beauties of nature, for our food and drink, for our
clothing, for our light and life, for the very possibility of our
existence, we are indebted to the Sun.
What is the Sun made of? Comte mentioned as a problem, which it was
impossible that man could ever solve, any attempt to determine the
chemical composition of the heavenly bodies. "Nous concevons," he said,
"la possibilité de déterminer leurs formes, leurs distances, leurs
grandeurs, et leurs mouvements, tandis que nous ne saurions jamais
étudier par aucun moyen leur composition chimique ou leur structure
minéralogique." To do so might well have seemed hopeless, and yet the
possibility has been proved, and a beginning has been made. In the early
part of this century Wollaston observed that the bright band of colours
thrown by a prism, and known as the spectrum, was traversed by dark
lines, which were also discovered, and described more in detail, by
Fraunhofer, after whom they are generally called "Fraunhofer's lines."
The next step was made by Wheatstone, who showed that the spectrum
formed by incandescent vapours was formed of bright lines, which
differed for each substance, and might, therefore, be used as a
convenient mode of analysis. In fact, by this process several new
substances have actually been discovered. These bright lines were found
on comparison to coincide with the dark lines in the spectrum, and to
Kirchhoff and Bunsen is due the credit of applying this method of
research to astronomical science. They arranged their apparatus so that
one-half was lighted by the Sun, the other by the incandescent gas they
were examining. When the vapour of sodium was treated in this way they
found that the bright line in the flame of soda exactly coincided with a
line in the Sun's spectrum. The conclusion was obvious; there is sodium
in the Sun. It must, indeed, have been a glorious moment when the
thought flashed upon them; and the discovery, with its results, is one
of the greatest triumphs of human genius.
The Sun has thus been proved to contain hydrogen, sodium, barium,
magnesium, calcium, aluminium, chromium, iron, nickle, manganese,
titanium, cobalt, lead, zinc, copper, cadmium, strontium, cerium,
uranium, potassium, etc., in all 36 of our terrestrial elements, while
as regards some others the evidence is not conclusive. We cannot as yet
say that any of our elements are absent, nor though there are various
lines which cannot as yet be certainly referred to any known substance,
have we clear proof that the Sun contains any element which does not
exist on our earth. On the whole, then, the chemical composition of the
Sun appears closely to resemble that of our earth.
THE PLANETS
The Syrian shepherds watching their flocks by night long ago
noticed--and they were probably not the first--that there were five
stars which did not follow the regular course of the rest, but,
apparently at least, moved about irregularly. These they appropriately
named Planets, or wanderers.
Further observations have shown that this irregularity of their path is
only apparent, and that, like our own Earth, they really revolve round
the Sun. To the five first observed--Mercury, Venus, Mars, Jupiter, and
Saturn--two large ones, Uranus and Neptune, and a group of minor bodies,
have since been added.
The following two diagrams give the relative orbits of the Planets.
[Illustration: Fig. 51.--Orbits of the inner Planets.]
MERCURY
It is possible, perhaps probable, that there may be an inner Planet,
but, so far as we know for certain, Mercury is the one nearest to the
Sun, its average distance being 36,000,000 miles. It is much smaller
than the Earth, its weight being only about 1/24th of ours. Mercury is a
shy though beautiful object, for being so near the Sun it is not easily
visible; it may, however, generally be seen at some time or other during
the year as a morning or evening star.
[Illustration: Fig. 52.--Relative distances of the Planets from the
Sun.]
VENUS
The true morning or evening star, however, is Venus--the peerless and
capricious Venus.
Venus, perhaps, "has not been noticed, not been thought of, for many
months. It is a beautifully clear evening; the sun has just set. The
lover of nature turns to admire the sunset, as every lover of nature
will. In the golden glory of the west a beauteous gem is seen to
glisten; it is the evening star, the planet Venus. A week or two later
another beautiful sunset is seen, and now the planet is no longer a
glistening point low down; it has risen high above the horizon, and
continues a brilliant object long after the shades of night have
descended. Again a little longer and Venus has gained its full
brilliancy and splendour. All the heavenly host--even Sirius and
Jupiter--must pale before the splendid lustre of Venus, the unrivalled
queen of the firmament."[67]
Venus is about as large as our Earth, and when at her brightest
outshines about fifty times the most brilliant star. Yet, like all the
other planets, she glows only with the reflected light of the Sun, and
consequently passes through phases like those of the Moon, though we
cannot see them with the naked eye. To Venus also owe we mainly the
power of determining the distance, and consequently the magnitude, of
the Sun.
THE EARTH
Our own Earth has formed the subject of previous chapters. I will now,
therefore, only call attention to her movements, in which, of course,
though unconsciously, we participate. In the first place, the Earth
revolves on her axis in 24 hours. Her circumference at the tropics is
24,000 miles. Hence a person at the tropics is moving in this respect at
the rate of 1000 miles an hour, or over 16 miles a minute.
But more than this, astronomers have ascertained that the whole solar
system is engaged in a great voyage through space, moving towards a
point on the constellation of Hercules at the rate of at least 20,000
miles an hour, or over 300 miles a minute.[68]
But even more again, we revolve annually round the Sun in a mighty orbit
580,000,000 miles in circumference. In this respect we are moving at the
rate of no less than 60,000 miles an hour, or 1000 miles a minute--a
rate far exceeding of course, in fact by some 100 times, that of a
cannon ball.
How few of us know, how little we any of us realise, that we are rushing
through space with such enormous velocity.
MARS
To the naked eye Mars appears like a ruddy star of the first magnitude.
It has two satellites, which have been happily named Phobos and
Deimos--Fear and Dismay. It is little more than half as large as the
Earth, and, though generally far more distant, it sometimes approaches
us within 35,000,000 miles. This has enabled us to study its physical
structure. It seems very probable that there is water in Mars, and the
two poles are tipped with white, as if capped by ice and snow. It
presents also a series of remarkable parallel lines, the true nature of
which is not yet understood.
THE MINOR PLANETS
A glance at Figs. 51 and 52 will show that the distances of the Planets
from the Sun follow a certain rule.
If we take the numbers 0, 3, 6, 12, 24, 48, 96, each one (after the
second) the double of that preceding, and add four, we have the series.
4 7 10 16 28 52 100
Now the distances of the Planets from the Sun are as follow:--
Mercury. Venus. Earth. Mars. Jupiter. Saturn.
3.9 7.2 10 15.2 52.9 95.4
For this sequence, which was first noticed by Bode, and is known as
Bode's law, no explanation can yet be given. It was of course at once
observed that between Mars and Jupiter one place is vacant, and it has
now been ascertained that this is occupied by a zone of Minor Planets,
the first of which was discovered by Piazzi on January 1, 1801, a worthy
prelude to the succession of scientific discoveries which form the glory
of our century. At present over 300 are known, but certainly these are
merely the larger among an immense number, some of them doubtless mere
dust.
JUPITER
Beyond the Minor Planets we come to the stupendous Jupiter, containing
300 times the mass, and being 1200 times the size of our Earth--larger
indeed than all the other planets put together. It is probably not
solid, and from its great size still retains a large portion of the
original heat, if we may use such an expression. Jupiter usually shows a
number of belts, supposed to be due to clouds floating over the surface,
which have a tendency to arrange themselves in belts or bands, owing to
the rotation of the planet. Jupiter has four moons or satellites.
SATURN
[Illustration: Fig. 53.--Saturn.]
Next to Jupiter in size, as in position, comes Saturn, which, though far
inferior in dimensions, is much superior in beauty. To the naked eye
Saturn appears as a brilliant star, but when Galileo first saw it
through a telescope it appeared to him to be composed of three bodies in
a line, a central globe with a small one on each side. Huyghens in 1655
first showed that in reality Saturn was surrounded by a series of rings
(see Fig. 53). Of these there are three, the inner one very faint, and
the outer one divided into two by a dark line. These rings are really
enormous shoals of minute bodies revolving round the planet, and
rendering it perhaps the most marvellous and beautiful of all the
heavenly bodies.
While we have one Moon, Mars two, and Jupiter four, Saturn has no less
than eight satellites.
URANUS
Saturn was long supposed to be the outermost body belonging to the solar
system. In 1781, however, on the 13th March, William Herschel was
examining the stars in the constellation of the Twins. One struck him
because it presented a distinct disc, while the true fixed stars,
however brilliant, are, even with the most powerful telescope, mere
points of light. At first he thought it might be a comet, but careful
observations showed that it was really a new planet. Though thus
discovered by Herschel it had often been seen before, but its true
nature was unsuspected. It has a diameter of about 31,700 miles.
Four satellites of Uranus have been discovered, and they present the
remarkable peculiarity that while all the other planets and their
satellites revolve nearly in one plane, the satellites of Uranus are
nearly at right angles, indicating the presence of some local and
exceptional influence.
NEPTUNE
The study of Uranus soon showed that it followed a path which could not
be accounted for by the influence of the Sun and the other then known
planets. It was suspected, therefore, that this was due to some other
body not yet discovered. To calculate where such a body must be so as to
account for these irregularities was a most complex and difficult, and
might have seemed almost a hopeless, task. It was, however, solved
almost simultaneously and independently by Adams in this country, and Le
Verrier in France.
Neptune, so far as we yet know the out-most of our companions, is 35,000
miles in diameter, and its mean distance from the Sun is 2,780,000,000
miles.
ORIGIN OF THE PLANETARY SYSTEM
The theory of the origin of the Planetary System known as the "Nebular
Hypothesis," which was first suggested by Kant, and developed by
Herschel and Laplace, may be fairly said to have attained a high degree
of probability. The space now occupied by the solar system is supposed
to have been filled by a rotating spheroid of extreme tenuity and
enormous heat, due perhaps to the collision of two originally separate
bodies. The heat, however, having by degrees radiated into space, the
gas cooled and contracted towards a centre, destined to become the Sun.
Through the action of centrifugal force the gaseous matter also
flattened itself at the two poles, taking somewhat the form of a disc.
For a certain time the tendency to contract, and the centrifugal force,
counterbalanced one another, but at length a time came when the latter
prevailed and the outer zone detached itself from the rest of the
sphere. One after another similar rings were thrown off, and then
breaking up, formed the planets and their satellites.
That each planet and satellite did form originally a ring we still have
evidence in the wonderful and beautiful rings of Saturn, which, however,
in all probability will eventually form spherical satellites like the
rest. Thus then our Earth was originally a part of the Sun, to which
again it is destined one day to return. M. Plateau has shown
experimentally that by rotating a globe of oil in a mixture of water and
spirit having the same density this process may be actually repeated in
miniature.
This brilliant, and yet simple, hypothesis is consistent with, and
explains many other circumstances connected with the position,
magnitude, and movements of the Planets and their satellites.
The Planets, for instance, lie more or less in the same plane, they
revolve round the Sun and rotate on their own axis in the same
direction--a series of coincidences which cannot be accidental, and for
which the theory would account. Again the rate of cooling would of
course follow the size; a small body cools more rapidly than a large
one. The Moon is cold and rigid; the Earth is solid at the surface, but
intensely hot within; Jupiter and Saturn, which are immensely larger,
still retain much of their original heat, and have a much lower density
than the Earth; and astronomers tell us on other grounds that the Sun
itself is still contracting, and that to this the maintenance of its
temperature is due.
Although, therefore, the Nebular Theory cannot be said to have been
absolutely proved, it has certainly been brought to a high state of
probability, and is, in its main features, generally accepted by
astronomers.
The question has often been asked whether any of the heavenly bodies are
inhabited, and as yet it is impossible to give any certain answer. It
seems _à priori_ probable that the millions of suns which we see as
stars must have satellites, and that some at least of them may be
inhabited. So far as our own system is concerned the Sun is of course
too hot to serve as a dwelling-place for any beings with bodies such as
ours. The same may be said of Mercury, which is at times probably ten
times as hot as our tropics. The outer planets appear to be still in a
state of vapour. The Moon has no air or water.
Mars is in a condition which most nearly resembles ours. All, however,
that can be said is that, so far as we can see, the existence of living
beings on Mars is not impossible.
COMETS
The Sun, Moon, and Stars, glorious and wonderful as they are, though
regarded with great interest, and in some cases worshipped as deities,
excited the imagination of our ancestors less than might have been
expected, and even now attract comparatively little attention, from the
fact that they are always with us. Comets, on the other hand, both as
rare and occasional visitors, from their large size and rapid changes,
were regarded in ancient times with dread and with amazement.
Some Comets revolve round the Sun in ellipses, but many, if not the
majority, are visitors indeed, for having once passed round the Sun
they pass away again into space, never to return.
The appearance which is generally regarded as characteristic of a Comet
is that of a head with a central nucleus and a long tail. Many, however,
of the smaller ones possess no tail, and in fact Comets present almost
innumerable differences. Moreover the same Comet changes rapidly, so
that when they return, they are identified not in any way by their
appearance, but by the path they pursue.
Comets may almost be regarded as the ghosts of heavenly bodies. The
heads, in some cases, may consist of separate solid fragments, though on
this astronomers are by no means agreed, but the tails at any rate are
in fact of almost inconceivable tenuity. We know that a cloud a few
hundred feet thick is sufficient to hide, not only the stars, but even
the Sun himself. A Comet is thousands of miles in thickness, and yet
even extremely minute stars can be seen through it with no appreciable
diminution of brightness. This extreme tenuity of comets is moreover
shown by their small weight. Enormous as they are I remember Sir G. Airy
saying that there was probably more matter in a cricket ball than there
is in a comet. No one, however, now doubts that the weight must be
measured in tons; but it is so small, in relation to the size, as to be
practically inappreciable. If indeed they were comparable in mass even
to the planets, we should long ago have perished. The security of our
system is due to the fact that the planets revolve round the Sun in one
direction, almost in circles, and very nearly in the same plane. Comets,
however, enter our system in all directions, and at all angles; they are
so numerous that, as Kepler said, there are probably more Comets in the
sky than there are fishes in the sea, and but for their extreme tenuity
they would long ago have driven us into the Sun.
When they first come in sight Comets have generally no tail; it grows as
they approach the Sun, from which it always points away. It is no mere
optical illusion; but while the Comet as a whole is attracted by the
Sun, the tail, how or why we know not, is repelled. When once driven
off, moreover, the attraction of the Comet is not sufficient to recall
it, and hence perhaps so many Comets have now no tails.
Donati's Comet, the great Comet of 1858, was first noticed on the 2d
June as a faint nebulous spot. For three months it remained quite
inconspicuous, and even at the end of August was scarcely visible to the
naked eye. In September it grew rapidly, and by the middle of October
the tail extended no less than 40 degrees, after which it gradually
disappeared.
Faint as is the light emitted by Comets, it is yet their own, and
spectrum analysis has detected the presence in them of carbon, hydrogen,
nitrogen, sodium, and probably of iron.
Comets then remain as wonderful, and almost as mysterious, as ever, but
we need no longer regard "a comet as a sign of impending calamity; we
may rather look upon it as an interesting and a beautiful visitor, which
comes to please us and to instruct us, but never to threaten or to
destroy."[69] We are free, therefore, to admire them in peace, and
beautiful, indeed, they are.
"The most wonderful sight I remember," says Hamerton, "as an effect of
calm, was the inversion of Donati's Comet, in the year 1858, during the
nights when it was sufficiently near the horizon to approach the rugged
outline of Graiganunie, and be reflected beneath it in Loch Awe. In the
sky was an enormous aigrette of diamond fire, in the water a second
aigrette, scarcely less splendid, with its brilliant point directed
upwards, and its broad, shadowy extremity ending indefinitely in the
deep. To be out on the lake alone, in a tiny boat, and let it rest
motionless on the glassy water, with that incomparable spectacle before
one, was an experience to be remembered through a lifetime. I have seen
many a glorious sight since that now distant year, but nothing to equal
it in the association of solemnity with splendour."[70]
SHOOTING STARS
On almost any bright night, if we watch a short time some star will
suddenly seem to drop from its place, and, after a short plunge, to
disappear. This appearance is, however, partly illusory. While true
stars are immense bodies at an enormous distance, Shooting Stars are
very small, perhaps not larger than a paving stone, and are not visible
until they come within the limits of our atmosphere, by the friction
with which they are set on fire and dissipated. They are much more
numerous on some nights than others. From the 9th to the 11th August we
pass through one cluster which is known as the Perseids; and on the 13th
and 14th November a still greater group called by astronomers the
Leonids. The Leonids revolve round the Sun in a period of 33 years, and
in an elliptic orbit, one focus of which is about at the same distance
from the Sun as we are, the other at about that of Uranus. The shoal of
stars is enormous; its diameter cannot be less than 100,000 miles, and
its length many hundreds of thousands. There are, indeed, stragglers
scattered over the whole orbit, with some of which we come in contact
every year, but we pass through the main body three times in a
century--last in 1866--capturing millions on each occasion. One of these
has been graphically described by Humboldt:
"From half after two in the morning the most extraordinary luminary
meteors were seen in the direction of the east. M. Bonpland, who had
risen to enjoy the freshness of the air, perceived them first. Thousands
of bodies and falling stars succeeded each other during the space of
four hours. Their direction was very regular from north to south. They
filled a space in the sky extending from due east 30° to north and
south. In an amplitude of 60° the meteors were seen to rise above the
horizon at east-north-east, and at east, to describe arcs more or less
extended, and to fall towards the south, after having followed the
direction of the meridian. Some of them attained a height of 40°, and
all exceeded 25° or 30°. No trace of clouds was to be seen. M. Bonpland
states that, from the first appearance of the phenomenon, there was not
in the firmament a space equal in extent to three diameters of the moon
which was not filled every instant with bolides and falling stars. The
first were fewer in number, but as they were of different sizes it was
impossible to fix the limit between these two classes of phenomena. All
these meteors left luminous traces from five to ten degrees in length,
as often happens in the equinoctial regions. The phosphorescence of
these traces, or luminous bands, lasted seven or eight seconds. Many of
the falling stars had a very distinct nucleus, as large as the disc of
Jupiter, from which darted sparks of vivid light. The bodies seemed to
burst as by explosion; but the largest, those from 1° to 1° 15' in
diameter, disappeared without scintillation, leaving behind them
phosphorescent bands (trabes), exceeding in breadth fifteen or twenty
minutes. The light of these meteors was white, and not reddish, which
must doubtless be attributed to the absence of vapour and the extreme
transparency of the air."[71]
The past history of the Leonids, which Le Verrier has traced out with
great probability, if not proved, is very interesting. They did not, he
considers, approach the Sun until 126 A.D., when, in their career
through the heavens, they chanced to come near to Uranus. But for the
influence of that planet they would have passed round the Sun, and then
departed again for ever. By his attraction, however, their course was
altered, and they will now continue to revolve round the Sun.
There is a remarkable connection between star showers and comets, which,
however, is not yet thoroughly understood. Several star showers follow
paths which are also those of comets, and the conclusion appears almost
irresistible that these comets are made up of Shooting Stars.
We are told, indeed, that 150,000,000 of meteors, including only those
visible with a moderate telescope, fall on the earth annually. At any
rate, there can be no doubt that every year millions of them are
captured by the earth, thus constituting an appreciable, and in the
course of ages a constantly increasing, part of the solid substance of
the globe.
THE STARS
We have been dealing in the earlier part of this chapter with figures
and distances so enormous that it is quite impossible for us to realise
them; and yet we have still others to consider compared with which even
the solar system is insignificant.
In the first place, the number of the Stars is enormous. When we look at
the sky at night they seem, indeed, almost innumerable; so that, like
the sands of the sea, the Stars of heaven have ever been used as
effective symbols of number. The total number visible to the naked eye
is, however, in reality only about 3000, while that shown by the
telescope is about 100,000,000. Photography, however, has revealed to us
the existence of others which no telescope can show. We cannot by
looking long at the heavens see more than at first; in fact, the first
glance is the keenest. In photography, on the contrary, no light which
falls on the plate, however faint, is lost; it is taken in and stored
up. In an hour the effect is 3600 times as great as in a second. By
exposing the photographic plate, therefore, for some hours, and even on
successive nights, the effect of the light is as it were accumulated,
and stars are rendered visible, the light of which is too feeble to be
shown by any telescope.
The distances and magnitudes of the Stars are as astonishing as their
numbers, Sirius, for instance, being about twenty times as heavy as the
Sun itself, 50 times as bright, and no less than 1,000,000 times as far
away; while, though like other stars it seems to us stationary, it is in
reality sweeping through the heavens at the rate of 1000 miles a minute;
Maia, Electra, and Alcyone, three of the Pleiades, are considered to be
respectively 400, 480, and 1000 times as brilliant as the Sun, Canopus
2500 times, and Arcturus, incredible as it may seem, even 8000 times, so
that, in fact, the Sun is by no means one of the largest Stars. Even the
minute Stars not separately visible to the naked eye, and the millions
which make up the Milky Way, are considered to be on an average fully
equal to the Sun in lustre.
Arcturus is, so far as we know at present, the swiftest, brightest, and
largest of all. Its speed is over 300 miles a second, it is said to be
8000 times as bright as the Sun, and 80 times as large, while its
distance is so great that its light takes 200 years in reaching us.
The distances of the heavenly bodies are ascertained by what is known as
"parallax." Suppose the ellipse (Fig. 54), marked Jan., Apr., July,
Oct., represents the course of the Earth round the Sun, and that A B are
two stars. If in January we look at the star A, we see it projected
against the front of the sky marked 1. Three months later it would
appear to be at 2, and thus as we move round our orbit the star itself
appears to move in the ellipse 1, 2, 3, 4. The more distant star B also
appears to move in a similar, but smaller, ellipse; the difference
arising from the greater distance. The size of the ellipse is inversely
proportional to the distance, and hence as we know the magnitude of the
earth's orbit we can calculate the distance of the star. The difficulty
is that the apparent ellipses are so minute that it is in very few cases
possible to measure them.
[Illustration: Fig. 54.--The Parallactic Ellipse.]
The distances of the Fixed Stars thus tested are found to be enormous,
and indeed generally incalculable; so great that in most cases, whether
we look at them from one end of our orbit or the other--though the
difference of our position, corresponding to the points marked January
and July in Fig. 54, is 185,000,000 miles--no apparent change of
position can be observed. In some, however, the parallax, though very
minute, is yet approximately measurable. The first star to which this
test was applied with success was that known as 61 Cygni, which is thus
shown to be no less than 40 billions of miles away from us--many
thousand times as far as we are from the Sun. The nearest of the Stars,
so far as we yet know, is [Greek: alpha] Centauri, the distance of which
is about 25 billions of miles.
The Pleiades are considered to be at a distance of nearly 1500 billions
of miles.
As regards the chemical composition of the Stars, it is, moreover,
obvious that the powerful engine of investigation afforded us by the
spectroscope is by no means confined to the substances which form part
of our system. The incandescent body can thus be examined, no matter how
great its distance, so long only as the light is strong enough. That
this method was theoretically applicable to the light of the Stars is
indeed obvious, but the practical difficulties are very great. Sirius,
the brightest of all, is, in round numbers, a hundred millions of
millions of miles from us; and, though as bright as fifty of our suns,
his light when it reaches us, after a journey of sixteen years, is at
most one two-thousand-millionth part as bright. Nevertheless, as long
ago as 1815 Fraunhofer recognised the fixed lines in the light of four
of the Stars; in 1863 Miller and Huggins in our own country, and
Rutherford in America, succeeded in determining the dark lines in the
spectrum of some of the brighter Stars, thus showing that these
beautiful and mysterious lights contain many of the material substances
with which we are familiar. In Aldebaran, for instance, we may infer the
presence of hydrogen, sodium, magnesium, iron, calcium, tellurium,
antimony, bismuth, and mercury. As might have been expected, the
composition of the Stars is not uniform, and it would appear that they
may be arranged in a few well-marked classes, indicating differences of
temperature, or perhaps of age.
Thus we can make the Stars teach us their own composition with light,
which started from its source years ago, in many cases long before we
were born.
Spectrum analysis has also thrown an unexpected light on the movements
of the Stars. Ordinary observation, of course, is powerless to inform
us whether they are moving towards or away from us. Spectrum analysis,
however, enables us to solve the problem, and we know that some are
approaching, some receding.
[Illustration: Fig. 55.--Displacement of the hydrogen line in the
spectrum of Rigel.]
If a star, say for instance Sirius, were motionless, or rather if it
retained a constant distance from the earth, Fraunhofer's lines would
occupy exactly the same position in the spectrum as they do in that of
the Sun. On the contrary, if Sirius were approaching, the lines would be
slightly shifted towards the blue, or if it were receding towards the
red. Fig. 55 shows the displacement of the hydrogen line in the spectrum
of Rigel, due to the fact that it is receding from us at the rate of 39
miles a second. The Sun affords us an excellent test of this theory. As
it revolves on its axis one edge is always approaching and the other
receding from us at a known rate, and observation shows that the lines
given by the light of the two edges differ accordingly. So again as
regards the Stars, we obtain a similar test derived from the Earth's
movement. As we revolve in our orbit we approach or recede any given
star, and our rate of motion being known we thus obtain a second test.
The results thus examined have stood their ground satisfactorily, and in
Huggins' opinion may be relied on within about an English mile a second.
The effect of this movement is, moreover, independent of the distance. A
lateral motion, say of 20 miles a second, which in a nearer object would
appear to be a stupendous velocity, becomes in the Stars quite
imperceptible. A motion of the same rapidity, on the other hand, towards
or away from us, displaces the dark lines equally, whatever the distance
of the object may be. We may then affirm that Sirius, for instance, is
receding from us at the rate of about 20 miles a second. Betelgeux,
Rigel, Castor, Regulus, and others are also moving away; while
some--Vega, Arcturus, and Pollux, for example--are approaching us. By
the same process it is shown that some groups of stars are only
apparently in relation to one another. Thus in Charles' Wain some of the
stars are approaching, others receding.
I have already mentioned that Sirius, though it seems, like other stars,
so stationary that we speak of them as "fixed," is really sweeping along
at the rate of 1000 miles a minute. Even this enormous velocity is
exceeded in other cases. One, which is numbered as 1830 in Groombridge's
_Catalogue of the Stars_, and is therefore known as "Groombridge's
1830," moves no less than 12,000 miles a minute, and Arcturus 22,000
miles a minute, or 32,000,000 of miles a day; and yet the distances of
the Stars are so great that 1000 years would make hardly any difference
in the appearance of the heavens.
Changes, however, there certainly would be. Even in the short time
during which we have any observations, some are already on record. One
of the most interesting is the fading of the 7th Pleiad, due, according
to Ovid, to grief at the taking of Troy. Again, the "fiery Dogstar," as
it used to be, is now, and has been for centuries, a clear white.
The star known as Nova Cygni--the "new star in the Constellation of the
Swan"--was first observed on the 24th November 1876 by Dr. Schmidt of
Athens, who had examined that part of the heavens only four days before,
and is sure that no such star was visible then. At its brightest it was
a brilliant star of the third magnitude, but this only lasted for a few
days; in a week it had ceased to be a conspicuous object, and in a
fortnight became invisible without a telescope. Its sudden splendour was
probably due to a collision between two bodies, and was probably little,
if at all, less than that of the Sun itself. It is still a mystery how
so great a conflagration can have diminished so rapidly.
But though we speak of some stars as specially variable, they are no
doubt all undergoing slow change. There was a time when they were not,
and one will come when they will cease to shine. Each, indeed, has a
life-history of its own. Some, doubtless, represent now what others
once were, and what many will some day become.
For, in addition to the luminous heavenly bodies, we cannot doubt that
there are countless others invisible to us, some from their greater
distance or smaller size, but others, doubtless, from their feebler
light; indeed, we know that there are many dark bodies which now emit no
light, or comparatively little. Thus in the case of Procyon the
existence of an invisible body is proved by the movement of the visible
star. Again, I may refer to the curious phenomena presented by Algol, a
bright star in the head of Medusa. The star shines without change for
two days and thirteen hours; then in three hours and a half dwindles
from a star of the second to one of the fourth magnitude; and then, in
another three and a half hours, reassumes its original brilliancy. These
changes led astronomers to infer the presence of an opaque body, which
intercepts at regular intervals a part of the light emitted by Algol;
and Vogel has now shown by the aid of the spectroscope that Algol does
in fact revolve round a dark, and therefore invisible, companion. The
spectroscope, in fact, makes known to us the presence of many stars
which no telescope could reveal.
Thus the floor of heaven is not only "thick inlaid with patines of
bright gold," but studded also with extinct stars, once probably as
brilliant as our own Sun, but now dead and cold, as Helmholtz tells us
that our Sun itself will be some seventeen millions of years hence.
Such dark bodies cannot of course be seen, and their existence, though
we cannot doubt it, is a matter of calculation. In one case, however,
the conclusion has received a most interesting confirmation. The
movements of Sirius led mathematicians to conclude that it had also a
mighty and massive neighbour, the relative position of which they
calculated, though no such body had ever been seen. In February 1862,
however, the Messrs. Alvan Clark of Cambridgeport were completing their
18-inch glass for the Chicago Observatory. "'Why, father,'" exclaimed
the younger Clark, "'the star has a companion.' The father looked, and
there was a faint star due east from the bright one, and distant about
ten seconds. This was exactly the predicted direction for that time,
though the discoverers knew nothing of it. As the news went round the
world many observers turned their attention to Sirius; and it was then
found that, though it had never before been noticed, the companion was
really shown under favourable circumstances by any powerful telescope.
It is, in fact, one-half of the size of Sirius, though only 1/10000th of
the brightness."[72]
Stars are, we know, of different magnitudes and different degrees of
glory. They are also of different colours. Most, indeed, are white, but
some reddish, some ruddy, some intensely red; others, but fewer, green,
blue, or violet. It is possible that the comparative rarity of these
colours is due to the fact that our atmosphere especially absorbs green
and blue, and it is remarkable that almost all of the green, blue, or
violet stars are one of the pairs of a Double Star, and in every case
the smaller one of the two, the larger being red, orange, or yellow. One
of the most exquisite of these is [Greek: beta] Cygni, a Double Star, the
larger one being golden yellow, the smaller light blue. With a telescope
the effect is very beautiful, but it must be magnificent if one could
only see it from a lesser distance.
Double Stars occur in considerable numbers. In some cases indeed the
relation may only be apparent, one being really far in front of the
other. In very many cases, however, the association is real, and they
revolve round one another. In some cases the period may extend to
thousands of years; for the distance which separates them is enormous,
and, even when with a powerful telescope it is indicated only by a
narrow dark line, amounts to hundreds of millions of miles. The Pole
Star itself is double. Andromeda is triple, with perhaps a fourth dark
and therefore invisible companion. These dark bodies have a special
interest, since it is impossible not to ask ourselves whether some at
any rate of them may not be inhabited. In [Greek: epsilon] Lyræ there
are two, each again being itself double. [Greek: xi] Cancri, and
probably also [Greek: theta] Orionis, consist of six stars, and from
such a group we pass on to Star Clusters in which the number is very
considerable. The cluster in Hercules consists of from 1000 to 4000. A
stellar swarm in the Southern Cross contains several hundred stars of
various colours, red, green, greenish blue, and blue closely thronged
together, so that they have been compared to a "superb piece of fancy
jewellery."[73]
The cluster in the Sword Handle of Perseus contains innumerable stars,
many doubtless as brilliant as our Sun. We ourselves probably form a
part of such a cluster. The Milky Way itself, as we know, entirely
surrounds us; it is evident, therefore, that the Sun, and of course we
ourselves, actually lie in it. It is, therefore, a Star Cluster, one of
countless numbers, and containing our Sun as a single unit.
It has as yet been found impossible to determine even approximately the
distance of these Star Clusters.
NEBULÆ
From Stars we pass insensibly to Nebulæ, which are so far away that
their distance is at present quite immeasurable. All that we can do is
to fix a minimum, and this is so great that it is useless to express it
in miles. Astronomers, therefore, take the velocity of light as a unit.
It travels at the rate of 180,000 miles a second, and even at this
enormous velocity it must have taken hundreds of years to reach us, so
that we see them not as they now are but as they were hundreds of years
ago.
It is no wonder, therefore, that in many of these clusters it is
impossible to distinguish the separate stars of which they are composed.
As, however, our telescopes are improved, more and more clusters are
being resolved. Photography also comes to our aid, and, as already
mentioned, by long exposure stars can be made visible which are quite
imperceptible to the eye, even with aid of the most powerful telescope.
Spectrum analysis also seems to show that such a nebula as that in
Andromeda, which with our most powerful instruments appears only as a
mere cloud, is really a vast cluster of stellar points.
This, however, by no means applies to all the nebulæ. The spectrum of a
star is a bright band of colour crossed by dark lines; that of a gaseous
nebula consists of bright lines. This test has been made use of, and
indicates that some of the nebulæ are really immense masses of
incandescent and very attenuated gas; very possibly, however, in a
condition of which we have no experience, and arranged in discs, bands,
rings, chains, wisps, knots, rays, curves, ovals, spirals, loops,
wreaths, fans, brushes, sprays, lace, waves, and clouds. Huggins has
shown that many of them are really stupendous masses of glowing gas,
especially of hydrogen, and perhaps of nitrogen, while the spectrum also
shows other lines which perhaps may indicate some of the elements which,
so far as our Earth is concerned, appear to be missing between hydrogen
and lithium. Many of the nebulæ are exquisitely beautiful, and their
colour very varied.
In some cases, moreover, nebulæ seem to be gradually condensing into
groups of stars, and in many cases it is difficult to say whether we
should consider a given group as a cluster of stars surrounded by
nebulous matter or a gaseous nebula condensed here and there into stars.
"Besides the single Sun," says Proctor, "the universe contains groups
and systems and streams of primary suns; there are galaxies of minor
orbs; there are clustering stellar aggregations showing every variety of
richness, of figure, and of distribution; there are all the various
forms of star cloudlets, resolvable and irresolvable, circular,
elliptical, and spiral; and lastly, there are irregular masses of
luminous gas clinging in fantastic convolutions around stars and star
systems. Nor is it unsafe to assert that other forms and varieties of
structure will yet be discovered, or that hundreds more exist which we
may never hope to recognise."
Nor is it only as regards the magnitude and distances of the heavenly
bodies that we are lost in amazement and admiration. The lapse of time
is a grander element in Astronomy even than in Geology, and dates back
long before Geology begins. We must figure to ourselves a time when the
solid matter which now composes our Earth was part of a continuous and
intensely heated gaseous body, which extended from the centre of the Sun
to beyond the orbit of Neptune, and had, therefore, a diameter of more
than 6,000,000,000 miles.
As this slowly contracted, Neptune was detached, first perhaps as a
ring, and then as a spherical body. Ages after this Uranus broke away.
Then after another incalculable period Saturn followed suit, and here
the tendencies to coherence and disruption were so evenly balanced that
to this day a portion circulates as rings round the main body instead of
being broken up into satellites. Again after successive intervals
Jupiter, Mars, the Asteroids, the Earth, Venus, and Mercury all passed
through the same marvellous phases. The time which these changes would
have required must have been incalculable, and they all of course
preceded, and preceded again by another incalculable period, the very
commencement of that geological history which itself indicates a lapse
of time greater than human imagination can realise.
Thus, then, however far we penetrate in time or in space, we find
ourselves surrounded by mystery. Just as in time we can form no idea of
a commencement, no anticipation of an end, so space also extends around
us, boundless in all directions. Our little Earth revolves round the
mighty Sun; the Sun itself and the whole solar system are moving with
inconceivable velocity towards a point in the constellation of Hercules;
together with all the nearer stars it forms a cluster in the heavens,
which appears to our eyes as the Milky Way; while outside our star
cluster again are innumerable others, which far transcend, alike in
magnitude, in grandeur, and in distance, the feeble powers of our finite
imagination.
FOOTNOTES:
[66] Ball, _Story of the Heavens_.
[67] Ball, _Story of the Heavens_.
[68] Some authorities estimate it even higher.
[69] Ball.
[70] Hamerton, _Landscape_.
[71] Humboldt, _Travels_.
[72] Clarke, _System of the Stars_.
[73] Kosmos.
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