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Title: A Treatise on the Origin, Progress, Prevention, and Cure of Dry Rot in Timber - With remarks on the means of preserving wood from - destruction by sea worms, beetles, ants, etc.
Author: Britton, Thomas Allen
Language: English
As this book started as an ASCII text book there are no pictures available.
*** Start of this LibraryBlog Digital Book "A Treatise on the Origin, Progress, Prevention, and Cure of Dry Rot in Timber - With remarks on the means of preserving wood from - destruction by sea worms, beetles, ants, etc." ***
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[Illustration:
SKETCH OF DRY ROT FUNGUS
_On basement floor joist in house, at Greenwich, near London Feb 1875._
END OF JOIST
_Crumbled into fine red powder, with slight rubbing._
TOP OF JOIST.
_Portion of fungus near the edge was torn away on removal of floor
boards, the undersides of which were covered with fungus, as well as the
sides of nearest joist 10ins. distant._
_Portion of fungus near the edge was torn away on removal of joist.
Fungus covered top and sides of sleeper joist._
_Colours of fungi. White, yellow, green, purple, and rusty red._]
A TREATISE
ON THE
OF
DRY ROT IN TIMBER.
WITH REMARKS ON
THE MEANS OF PRESERVING WOOD FROM DESTRUCTION BY
SEA WORMS, BEETLES, ANTS, ETC.
BY
THOMAS ALLEN BRITTON,
LATE SURVEYOR TO THE METROPOLITAN BOARD OF WORKS, AND SILVER
MEDALLIST OF THE ROYAL INSTITUTE OF BRITISH ARCHITECTS IN 1854,
1856, AND 1870.
[Illustration]
LONDON:
E. & F. N. SPON, 48, CHARING CROSS.
NEW YORK: 446, BROOME STREET.
1875.
THIS VOLUME
IS
Dedicated to
GEORGE VULLIAMY, ESQ.,
VICE-PRESIDENT
OF THE
ROYAL INSTITUTE OF BRITISH ARCHITECTS;
AND
ARCHITECT
OF
THE METROPOLITAN BOARD OF WORKS;
AS A SLIGHT ACKNOWLEDGMENT
OF HIS
COUNSEL, SYMPATHY, AND FRIENDSHIP,
DURING MANY YEARS.
PREFACE.
In preparing this treatise on Dry Rot, the author has endeavoured
to place in as condensed a form as was consistent with the nature
of the subject, the knowledge and information dispersed through a
numerous collection of writers who have treated thereon; he has also
availed himself of the assistance of professional friends, builders,
timber-merchants, foremen and carpenters; and, by so doing, has been
enabled to record several instances of the progress and cure of dry
rot. He has consulted many valuable papers published during the last
thirty years, in the various professional journals in England, America,
France, and Germany, upon this important subject, and has also obtained
much useful information from the works of Evelyn, Nicholson, Tredgold
by Hurst, Papworth, Burnell, Blenkarn, and other English writers upon
timber; Silloway, of North America; Porcher, of South America; Du Hamel,
De Moray, and De Lapparent, of France; and several writers whose works
will be referred to.
It is many years since a separate and complete work on dry rot has been
published, and those who are desirous of inquiring into the matter are
frequently at a loss where to obtain any information. Existing works on
the subject are out of print, and although they can be seen at a few
professional institutes, they are beyond the reach of the general public.
It has been the aim of the author in preparing this treatise to give a
fair hearing to every patentee, and he has endeavoured to be as impartial
as possible in recording instances of failure and success. If he has
erred in any particular case, he will be happy, should this work reach a
second edition, to make any necessary correction.
The reader will probably find some things repeated in the course of the
work; this is in many cases unavoidable, and in some advisable; for if by
a little tautology important truths can be impressed upon the mind of the
reader, the author will feel that his labour in preparing this work has
not been altogether in vain.
Modern authorities have been relied upon in preference to ancient ones:
the following sentence, written by the late Sydney Smith, is quoted as a
reason for so doing:
“Those who come first (our ancestors) are the young people, and have the
least experience. We have added to their experience the experience of
many centuries; and, therefore, as far as experience goes, are wiser, and
more capable of forming an opinion than they were.”
20, LIMES GROVE, LEWISHAM,
_May 14th, 1875_.
CONTENTS.
CHAPTER I.
On the Nature and Properties of Timber Page 1
CHAPTER II.
On the Gradual Rise and Development of Dry Rot 14
CHAPTER III.
On Felling Timber 51
CHAPTER IV.
On Seasoning Timber by Natural Methods, viz. Hot and Cold Air;
Fresh and Salt Water; Vapour; Smoke; Steam; Boiling; Charring
and Scorching, &c. 63
CHAPTER V.
On Seasoning Timber by Patent Processes, &c. 105
CHAPTER VI.
On the Means of Preventing Dry Rot in Modern Houses 171
CHAPTER VII.
On the Means of Preservation of Wooden Bridges, Jetties, Piles,
Harbour Works, &c., from the Ravages of the _Teredo navalis_ and
other Sea-worms 203
CHAPTER VIII.
On the Destruction of Woodwork in Hot Climates by the _Termite_
or White Ant, Woodcutter, Carpenter Bee, &c.; and the Means of
Preventing the Same 240
CHAPTER IX.
On the Causes of Decay in Furniture, Wood Carvings, &c.; and the
Means of Preventing and Remedying the Effects of such Decay 262
CHAPTER X.
Summary of Curative Processes 283
CHAPTER XI.
General Remarks and Conclusion 288
INDEX 295
ILLUSTRATIONS.
DRY ROT ON FLOOR JOIST _Frontispiece_
_To face page_
TIMBER BEAMS--ROTTEN AT THE HEART 34
BALTIC MODES OF CUTTING DEALS 64
MR. KYAN’S TIMBER PRESERVING TANK 126
MESSRS. BETHELL AND CO.’S TIMBER PRESERVING APPARATUS 136
TIMBER PILES FROM BALACLAVA HARBOUR 208
DESTRUCTION OF TIMBER PILE BY TEREDO 212
SHELL AND CELL OF TEREDO NAVALIS 216
PILES, SOUTHEND PIER; LIMNORIA, &C. 220
CARPENTER BEES AT WORK 260
A TREATISE ON DRY ROT IN TIMBER.
CHAPTER I.
ON THE NATURE AND PROPERTIES OF TIMBER.
In considering the subject of Timber trees, we commence with their
Elementary Tissues, and first in order is the _Formative Fluid_, which
is the sole cause of production of every tissue found in trees. It
is semi-fluid, and semi-transparent, and in this condition is found
abundantly between the bark and the wood of all trees in early spring;
and thus separates those parts so as to permit the bundles of young wood
to pass down from the leaves, and thus enable the tree to grow. It is
under these conditions that the woodman strips the bark from trees which
are to be cut down, since then it does not adhere to the wood.
The first step in the formation of any tissue from the formative fluid
is the production of a solid structureless fabric called _Elementary
Membrane_, and a modification of that fabric termed _Elementary Fibre_.
The structures which are produced from the above-mentioned “raw
material” are very varied in appearance, and are called _Cellular
Tissues_, to signify that they are made up of hollow cells. The spaces
between the cells are called _Intercellular Spaces_, which are of vital
importance, as they contain air. _Woody fibre_ constitutes the mass of
the stems of our forest trees. Its peculiar characteristic is that of
great tenacity, and power of resistance, and for this its structure is
admirably adapted: it consists of bundles of very narrow fibres, with
tapering extremities, and is so placed from end to end, that the pointed
ends overlap each other. Each fibre is very short, and the partitions
which result from the apposition of the fibres, end to end, do not
interfere with the circulation through them. The tube is not composed
of simple thin membranes only; but in addition has a deposit within it,
which, without filling the tube, adds very greatly to the strength of
the fibre: an arrangement whereby the greatest strength and power of
resistance and elasticity shall be obtained; and, at the same time, the
functions of circulation uninterruptedly maintained. The strength is
mainly due to the shortness of each fibre, the connection by opposite
ends of many fibres, almost in one direct line, from the root upwards;
and lastly, to the deposit on the inner side of the membrane. The uses
of woody fibre are very varied and most important; it is the chief organ
of circulation in all wooded plants, and, for this purpose, pervades
the plant from the root to the branches. The current in this tissue
is directed upwards from the shoot, through the stem to the leaves,
and downwards from the leaves through the bark to the root. Thus, its
current has a twofold tendency; the ascending and chief one being for
the purpose of taking the raw, or what is called the _common sap_, from
the ground to be digested in the leaves, and the descending being devoted
to the removal from the leaves of the digested, or what is termed the
_proper sap_, to be applied to the purposes of the tree, and also of the
refuse matter to be carried to the roots, and thence thrown out into the
soil as a noxious material. The _proper sap_ differs considerably in
different trees; it is always less liquid, and contains a much greater
proportion of vegetable matter than the common sap. It is very probable
that trees of the same kind produce proper sap of different qualities in
different climates.
WOODY FIBRE may be considered the storehouse of the perfected secretions.
It is well known that as trees advance in life, the wood assumes a darker
colour, and more particularly that lying near to the centre of the stem.
This is due to the deposit of the perfected juices in the woody fibre at
that point; and where age has matured the tree, it is probable that the
woody fibre so employed is no longer fitted for the circulation of the
sap; and, also, that the perfected sap, when once deposited, does not
again join in the general circulation. The dark colour of the heart of
oak, as contrasted with oak of very recent growth, is an illustration
of this fact, as is also the deep colour which is met with in ebony and
rose-wood. Technically, the inner wood is called the heart-wood, and the
outer or younger wood the sap-wood. Of these, the former contains little
fluid, and no vegetable life, and, being the least liable to decay, is
therefore the most perfect wood; the latter is soft and perishable in
its nature, abounding in fermentable elements; thus affording the very
food for worms, whose destructive inroads hasten its natural tendency to
decay.
The proportion of sap-wood in different trees varies very much. Spanish
chestnut has a very small proportion of sap-wood, oak has more, and fir a
still larger proportion than oak; but the proportions vary according to
the situation and soil, and according to the age at which they have been
felled: for instance, the teak tree in Malabar, India, differs from teak
in Anamalai, South India. This subject has been very fully treated by Mr.
Patrick Williams, in his valuable work on Naval Timber.
WOODED STEMS are divided into two great and well-defined classes,
according to their internal conformation, viz. such as grow from without
(exogenous), and such as enlarge from within (endogenous). The former are
more common in cold, and the latter in hot climates.
EXOGENOUS STEMS.--On examining a section of a stem of an oak, or any
other of our forest trees, we observe the following parts: first, the
pith, or its remains in the centre; second, the bark on the outside;
third, a mass of wood between the two, broken up into portions by the
concentric deposition of the layers, and by a series of lines which
pass from the centre to the circumference. Thus, there are always pith,
bark, wood, and medullary rays. Each stem has two systems, the cellular
or horizontal, and the vascular or longitudinal, and the parts just
mentioned must belong to one or other of those systems. Thus, the pith,
medullary rays, and bark belong to the horizontal system; and the wood
constitutes the longitudinal system.
THE PITH occupies the centre of the stem, and remains throughout the
period of growth of some trees, as of the elder; or is abstracted after
a few years, as in the oak, and almost all large trees. In the latter
class of trees, there are some remains of the pith for many years after
the process of absorption has commenced, but at length no vestige can
be detected, and its position is known only by the central spot around
which the wood is placed in circles. In the old age of the tree the pith
frequently assumes a colour which it has obtained from the juices which
have been deposited. The connections of the pith are extremely important.
Firstly, it is in direct connection with every branch, and is the
structure which first conveys fluids to, and receives fluids from every
new leaf. It thence becomes the main organ of nutriment, and, at the same
time, the chief depository of the secretions. Secondly, it is in equally
direct and unbroken connection with the bark, through the medium of the
medullary rays; and so becomes the centre of all the movements of sap
which proceed in the horizontal system.
The mode in which the ultimate disappearance of the pith occurs has been
a matter of speculation. That the circulation in the heart-wood ceases
after a certain number of years, and that the connection between it and
the bark becomes broken, is proved by the fact that numbers of trees
may be found in tolerably vigorous growth within the bark, whereas at
the heart they are decayed and rotten. It appears clear that it is not
converted into wood, and there are facts against the opinion that it
is gradually compressed by the wood; but since it is known that in the
growth of the tree much compression of the previously formed wood must
occur, and since this compression is a likely theory by which to account
for the disappearance of the less resisting pith, it is now generally
considered to be one of the causes of this occurrence. As a general rule,
the pith, so long as it exists, is not mingled with other than cellular
structures; but, in certain instances, wooden fibre has been found with
it, and, in others, spiral vessels have been detected.
MEDULLARY SHEATH.--Immediately surrounding the pith of all exogenous
plants, there is a layer of longitudinal tissue, which has received
the name of medullary sheath. This sheath has no special walls, but is
bounded by the pith on the inner, and the wood on the outer side. It is
in this situation that ducts of various kinds and spiral vessels may be
found, and in all cases it conveys the longitudinal structure from the
root, direct to each leaf. The integrity of this structure is therefore
highly necessary to the life of the tree.
MEDULLARY RAYS.--These structures come next in order, and, as has been
previously intimated, belong to the horizontal cellular system of the
stem; they constitute the channel of communication between the bark and
the pith, and are composed of a series of walls of single cells resting
upon the root, and proceeding to the top of the tree, and radiating from
the centre. They lie between the wedge-like blocks of wood, and as they
have a lighter colour than the wood, they are evident on an oblique
section of any stem, and are called the silver grain. Their colour and
number suffice to enable anyone to distinguish various kinds of wood, and
greatly increase their beauty. They cannot, of course, exist before the
wood is formed, and are therefore not met with in very young trees. They
commence to exist with the first deposited layers of wood, and continue
to grow outwardly, or nearest to the bark, so long as the wood continues
to be deposited. In those woods which possess in abundance the silver
grain, another source of ornament exists, viz. a peculiar damask or
dappled effect, somewhat similar to that artificially produced on damask
linens, moreens, silks, and other fabrics, the patterns on which result
from certain masses of the threads on the face of the cloth running
lengthways, and other groups crossways. This effect is observable in a
remarkable degree in the more central planks of oak, especially in Dutch
wainscot.
THE BARK.--As the medullary rays terminate in the bark, on their outer
side, the consideration of that part next follows. It forms the sheath
of the tree, and its more immediate use is that of giving protection to
the wood. If bark did not exist, there would be no formative fluid, and
without formative fluid there could not be any deposit of woody fibre.
WOOD.--We find wood occupying nearly the whole body of the trunk of the
tree, and arranged, as a rule, in a very regular manner. On taking up
any piece of wood, but more particularly the entire section of a stem,
we first notice a series of circles, which increase in diameter and
separate by wider intervals as we approach the bark. In this manner the
trunk is composed of numerous zones enclosed within each other. Again,
in almost all trees, the medullary rays before mentioned may be observed
passing in straight lines from the centre to the circumference; and, as
the circle of the stem at the bark is much larger than any circle near to
the centre, it follows that the medullary rays will be wider apart at the
bark than at the pith. On this view of the subject it may be stated that
the stem is composed of a series of wedge-shaped blocks, which have their
edges meeting at the centre. The combination of these two views gives the
correct idea of the arrangement of the wood, viz. a series of wedges,
each divided into segments of unequal width by circular lines passing
across them. From this description it must not be imagined that these
various portions are detached from each other; for although the medullary
rays and the circular mode of deposition both tend to a less difficult
cleavage of the wood, they yet bind the parts very closely to each other.
The explanation of the occurrence of distinct zones of wood is, that each
zone is the produce of one year, and that in our climate, more so than in
tropical climates, the period of growth of wood ceases for many months
between the seasons, and this induces a distinction in appearance between
the last wood of a former, and the first wood of a succeeding year. This
distinction is maintained throughout each year, and throughout a long
series of years.
The enclosure of zone within zone, is owing to the mode in which the wood
is produced, and the position in which it is deposited. Wood is formed by
the leaves during the growing season, and passes down towards the root
between the bark and the wood of the previous year; and, as the leaves
more or less surround the whole stem, the new layer at length completes
a zone, and perfectly encloses the wood of all former years. This is
the explanation of the term exogenous, which is derived from two words
signifying to grow, outwardly, for the stem increases in thickness by
successive layers on the outer side of the previously formed wood.
The thickness of the zone for the year is rarely equal around the whole
circumference of the stem, and this is due to the lesser abundance
of leaves on the branches of one side than on the other, or to the
prevalence of winds, or some other physical cause, acting in that
direction in opposition to the growing process. It should be observed
that there is not in timber any appearance of a gradual change from
alburnum to perfect wood. On the contrary, in all cases the division is
most decided; one concentric layer being perfect wood, and the next in
succession sap-wood.
The age of trees has been inferred, when a section of the whole stem
could be examined, by counting the number of rings of wood which have
been deposited around the pith. In tropical countries, however, this
method cannot be always relied upon.
Woods are variable in quality according to the nature of the climate, and
of the soil, as also in a considerable degree to the aspect in which they
are situated. Trees grown slowly in open, dry, and exposed situations
are more fine and close in their annual rings, and more substantial
and durable, than those which are grown in close and shady forests, or
rapidly reared in moist or sappy places, the latter being soft and broad
in their rings, and very subject to decay; and their pith is not always
quite in the centre, for the layers are variable also.
The waggon maker takes care to combine toughness and durability by
selecting his wood from trees of second growth, or from trees of first
growth that from infancy have stood alone, or far apart. If the soft wood
trees have stood alone, and are very large (as is often the case with
some of the pines), and most of the branches are near the top, the wood
near the base of the trunk is sometimes found to be _shaky_. This defect
is produced by the action of heavy winds on the top of the tree, which
wrenches or twists the butt, and thus cleaves apart the fibres of the
wood. If the main-top (_couronnement_, of French writers) of a tree dies
while the tree is yet standing, it indicates that water has found its way
into the trunk, and that the tree is in a state of decay.
The fir which grows on very dry marl, forms very narrow yearly rings; if
on rich or damp marl, they are wide; and when on wet soil, they are again
smaller. The common fir on moor soil, has even smaller yearly rings than
if on dry sand or marl. From this it is evident that too wet or too dry a
soil is not suitable for this tree.
The alder and the willow grow best on wet soil, and thrive but poorly
when standing dry.
The weight of wood is of great importance, because its hardness,
resistance, and its heating power, as well as other valuable properties,
are all more or less depending upon it. In the first place, we must
consider that even wood which has been forested very light will become
heavy, when put for some time into water, but in such timbers the sap is
already given to dissolution. If the fibre were the only substance in
the wood, then the specific weight would depend upon the number of pores
contained in its body; the pores are, however, filled with a substance
such as resin, die, &c. Some years since, when the Indian railways
were being formed, the native wood-cutters were so well aware of the
above-mentioned fact, that they used to cut down the soft and inferior
woods in the forests; soak them in water for a certain time; and then
endeavour to pass them to the railway contractors as sound, heavy, and
good railway sleepers, and the latter, not being acquainted with the
Indian woods, were, at first, often deceived.
The hardest, and heaviest woods come from the hotter climates; the only
exception is the pine, which thrives considerably better, and furnishes
heavier timber, when it has grown in colder regions, or upon high
mountains.
Trees grown on northern slopes furnish lighter timber than if grown on
southern or western. The soil has great influence upon the width of the
yearly rings, and from this we are able to come to a conclusion in regard
to the specific weight. In the fir and larch trees the wood is heaviest
when their rings are smallest.
The difference in the strength of timber between the south and the
north side is attributable to the grain being closer on the north side,
as the sap does not rise in the same proportion as upon the south.
In forest-grown wood the difference is almost imperceptible, as the
sun cannot act upon the trunk of the tree; in open-grown timber, the
difference is really perceptible. It is well known that all woods do not
lose strength by being open grown, or, in other words, that the south
side is not always weaker than the north; that theory only applies to
the coniferæ species. In ash it is the opposite, as the south side is
the strongest. In soft-wooded trees, as the acer species, the difference
is not perceptible, as the annual rings, and the intervening cellular
tissues, are so close akin as to render the wood so compact in its grain
that there is no difference in its strength. The coniferæ species, or the
pines, are the only classes of woods that are stronger on the north side
than on the south: it is well known that the difference originates in the
wood being more open in the grain on the south side than on the north.
An influence upon the specific weight is exercised by the resin, and
the die, which are contained in the interior of the wood. On level dry
ground, or deep sandy soil, we find the fir beautifully red inside;
but when we look at it on lias soil, it shows broad yearly rings, and
hardly any colour at all. The larch tree, again, in such soil, develops
itself well with a rich colour. The cause for these appearances must
therefore rest with the chemical condition of the soil, and its effect
upon the individuality of the fir: it is probably the nature of the soil
that causes the difference of character between Honduras and Spanish
mahogany; Honduras being full of black specks, and Spanish of minute
white particles, as if it had been rubbed over with chalk. Oaks generally
furnish good timber when grown slowly in dry ground, whilst those from
wet soil appear comparatively spongy; similar results are obtained with
other trees.
Many persons constantly employed on wood are of opinion that it becomes
harder if it is worked or barked whilst green.
It is not safe to condemn timber, merely because long cracks are visible
on the surface. Such openings are frequently only superficial, and do not
penetrate deeply into the wood: in such cases it is very little weakened
thereby. It is difficult to obtain timber of large scantling without some
defects of this kind, but care should be taken to ascertain if they are
of a serious nature.
Trees arrive at an age when their wood becomes ripe, and then they are
fit for felling; but as upon the proper method and time for doing this,
the prevention of dry rot frequently hinges, a separate chapter is
devoted to this part of the subject.
CHAPTER II.
ON THE GRADUAL RISE AND DEVELOPMENT OF DRY ROT.
The opinion generally received has drawn a line of discrimination between
the decay accompanied by a vegetable spreading on the surface of the
timber, and that which is effected by an animal existing within it,
which decay is frequently denominated the worm in timber; but as each is
equally entitled to the dreaded appellation, they might more justly be
distinguished as the animal and vegetable rot.
The dry rot in timber derives its name from the effect produced, and
not from the cause: it is so called in opposition to the wet rot, which
is properly denominated, as this exists only in damp situations, and is
applied to the decomposition which takes place in timber containing sap,
and exposed to moisture: but although the dry rot is usually generated
in moisture, in some cases it will flourish independent of extraneous
humidity. Dry rot differs from wet rot in this respect, that the former
takes place only when the wood is dead, whereas the latter may begin when
the tree is standing.
Wet rots are composed of porous fibre running from the rot into the
trunk of the tree. This rot is of a brown colour, and has an offensive
smell. The evil is often found with white spots, the latter of watery
substance: when it has yellow flames, it is very dangerous.
A large quantity of the vegetable kingdom consists of plants differing
totally from the flowering plants in general structure, having no
flowers and producing no seed properly so called, but propagating by
means of minute cellular bodies, called _spores_. These highly organized
vegetables are known to botanists as _Cryptogamia_. Fungi are plants in
which the fructifying organs are so minute, that without the aid of a
powerful microscope they cannot be detected. To the naked eye, the fine
dust ejected from the plant is the only token of reproduction; this dust,
however, is not truly seed, for the word seed supposes the existence
of an embryo, and there is no such thing in the reproductive bodies of
fungi. The correct terms are _spores_, when the seeds are not in a case;
_sporidia_ when enclosed in cases. The spores or sporidia are placed
in or upon the receptacle, which is of very various forms and kinds,
but how different soever these may be, it is the essential part of the
fungus, and in many cases constitutes the entire plant. That portion of
the receptacle in which the reproductive bodies are imbedded is called
the _hymenium_: it is either external, as in the Agaric, where it forms
gills; or included, as in the puff-balls. The _pileus_ of fungi is the
entire head of the plant, not a mere head covering.
Some naturalists have insisted upon the spontaneous production of fungi,
while others maintain that they are produced by seed, which is taken
up and supported in the air until a soil proper for its nourishment is
presented, on which being deposited it springs up of various appearances
according to the principle of the seed, and the nature of the recipient.
It is extremely difficult to give a logical definition of what
constitutes a fungus. It is not always easy with a cursory observation
under the microscope, to determine whether some appearances are produced
by fungi, insects, or organic disease; experience is the safest guide,
and until we acquire that we shall occasionally fail.
In the ‘Index Fungorum Britannicorum,’ 2479 species of British fungi are
enumerated: any detailed account of the arrangement of this extensive
family of plants, or of the character of even its principal sections
would be impossible within the limits of this volume; all that can be
attempted will be a general description of the fungi causing dry rot.
If dry rot shows itself in a damp closet or pantry, the inside of
the china or delf lying there will be coated with a mould, or a fine
powder like brick-dust. This excessively fine powder is no other than
unaccountable myriads of the reproductive spores or _seeds_ of the
fungus; they are red in colour, and are produced on the surface of the
fungus in millions. Certain privileged cells on the face of the fungus
are furnished each with four minute points at their apex, each four
bearing a single brick-red, egg-shaped spore; so that the fruit is spread
over the surface of the fungus in groups of fours. To see the form of
these spores the highest powers of the microscope are required, and then
they can only be viewed as transparent objects. If these excessively
minute bodies be allowed to fall on wet flannel, damp blotting-paper, or
wet wood, they immediately germinate and proceed to reproduce the parent
fungus. The red skin of the spores cracks at both ends, and fine mycelial
filaments are sent out: this is the “mould,” spawn, or mycelium from
which the new fungus (under favourable conditions of continued moisture)
appears.
It matters little where we go: everywhere we are surrounded with life.
The air is crowded with birds and insects; the waters are peopled with
innumerable forms, and even the rocks are blackened with countless
mussels and barnacles. If we pluck a flower, in its bosom we see many a
charming insect. If we pick up a fallen leaf, there is probably the trace
of an insect larvæ hidden in its tissue. The drop of dew upon this leaf
will probably contain its animals, visible under the microscope. The
very mould which covers our cheese, our bread, our jam, or our ink, and
disfigures our damp walls, is nothing but a collection of plants.
The starting point of life is a single cell-that is to say a microscopic
sac filled with liquid and granules, and having within it a nucleus,
or smaller sac. From this starting point of a single cell, this is the
course taken: the cell divides itself into two, the two become four, the
four eight, and so on, till a mass of cells is formed.
The researches of Pasteur show that atmospheric dust is filled with
minute germs of various species of animals and plants, ready to develop
as soon as they fall into a congenial locality. He concludes that all
fermentation is caused by the germination of such infinitesimal spores.
That they elude observation does not seem strange, when we consider that
some infusoria are only ⅟240000 of an inch in length.
It is ascertained that fungi produce seed which contains the properties
of germination; and that vegetable corruption is suited to effect it.
When we contemplate the fineness and volatility of the germs, the
hypothesis will not appear unreasonable that they are conveyed by the
rains into the earth, and are absorbed by vegetables; that with the
sap they are disseminated throughout the whole body, and begin to
germinate as soon as the vegetable has proceeded to corruption. Whatever,
therefore, may be the appearance or situation of the fungus producing the
dry rot, or from whatever substance it originates, that substance must be
in a corrupt state.
Fungi result from, or are attendant on, vegetable corruption, assisted
by an adequate proportion of heat and moisture. The sap, or principle
of vegetation, brought into activity, is, according to the ‘Quarterly
Review,’ No. 15, the cause of dry rot, in as far as it is favourable
to the growth of fungi, as it would seem to be when in a state of
fermentation.
Vegetable corruption invariably presupposes fermentation.
Fermentation is a state of vegetable matter, the component parts of which
have acquired sufficient force to produce an intestinal motion, by which
the earthy saline, the oily and aqueous particles therein contained,
exert their several peculiar attractive and repulsive powers, forming new
combinations, which at first change, and at length altogether destroy
the texture of the substance they formerly composed.
There are two things essential towards creating and supporting the
intestinal motion, namely, heat and humidity; for without heat, the air,
which is supposed to be the cohesive principle of all bodies, cannot be
so rarefied as to resume its elasticity; and without humidity there can
be no intestinal motion.
According to Baron Liebig, the decay of wood takes place in the three
following modes:--First, oxygen in the atmosphere combines with the
hydrogen in the fibre, and the oxygen unites with the portion of carbon
of the fibre, and evaporates as carbonic acid: this process is called
decomposition. Second, we have to notice the actual decay of wood which
takes place when it is brought in contact with rotting substances; and
the third process is called putrefaction. This is stated by Liebig to
arise from the inner decomposition of the wood in itself: it loses its
carbon, forms carbonic acid gas, and the fibre, under the influence of
the latter, is changed into white dust.
The fungus occasioning the dry rot is of various appearances, which
differ according to the situation in which it exists. In the earth, it
is fibrous and perfectly white, ramifying in the form of roots; passing
through substances from the external surface, it somewhat differs from
that form; here it separates into innumerable small branches.
Mr. McWilliam observes, “If the fungi proceed from the slime in the
fissures of the earth, they are generally very ramous, having round
fibres shooting in every direction. If they arise from the roots of
trees, their first appearance is something like hoar frost; but they soon
assume the mushroom shape.”
Hence it appears that we frequently build on spots of ground which
contain the fundamental principle of the disease, and thus we are
sometimes foiled in our endeavours to destroy the fungus by the admission
of air. In this case the disease may be encouraged by the application of
air as a remedy. When workmen are employed in buildings which contain dry
rot, and when they are working on ground which contains the symptoms of
this disease, their health is often affected. A London builder informs
us, that a few years since, while building some houses at Hampstead
his men were never well: he afterwards ascertained that the ground was
affected with rot, and that within one year after the house was erected,
all the basement floor was in a state of premature decay. Sir Robert
Smirke, architect, remarked in 1835, that he had noticed “there are
certain situations in which dry rot prevails remarkably.”
The fungus protruded in a very damp situation is fibrous, of moderate
thickness, feels fleshy. From the spot whence it arises it extends
equally around, wholly covering the area of a circle. This form would
possibly continue in whatever situation it might vegetate, if the air had
no motion, and every part of the substance on which it grew were equally
supplied with a matter proper to encourage the expansion. The surface of
this fungus is pursed, and of various colours, the centre is of a dusky
brown, mixed with green, graduated into a red, which degenerates into
yellow, and terminates in white.
One of the most formidable of the tribe of fungi is the _Merulius
lachrymans_ (often called _the_ Dry Rot) of which the following
description is given by Dr. Greville: “Whole plant generally resupinate,
soft, tender, at first very light, cottony, and white. When the veins
appear, they are of a fine yellow, orange, or reddish brown, forming
irregular folds, most frequently so arranged as to have the appearance
of pores, but never anything like tubes, _and distilling, when perfect,
drops of water_.” Hence the term _lachrymans_, from _lacrymo_, Lat., I
weep: the _Merulius lachrymans_ is often dripping with moisture, as if
weeping in regret for the havoc it has made. In the genus _Merulius_,
the texture is soft and waxy, and the hymenium is disposed in porous or
wavy toothed folds. Berkeley, in his ‘Fungology,’ gives the following
description, which is similar to Dr. Greville’s: “Large, fleshy but
spongy, moist, ferruginous yellow, arachnoid and velvety beneath;
margin tomentose, white; folds ample, porous, and gyroso-dentate.” The
_Merulius_ is found in cellars and hollow trees, sometimes several feet
in width, and is the main cause of dry rot.
Another formidable fungi, which attacks oak in ships, is the _Polyporus
hybridus_ (the dry rot of our oak-built vessels). It is thus described by
Berkeley: “White, mycelium thick, forming a dense membrane, or creeping
branched strings, hymenium breaking up into areæ, pores long, slender,
minute.”
From the slow progress dry rot makes in damp situations, it appears
that excessive damps are inimical to the fungus, for its growth is more
rapid in proportion as the situation is less damp, until arrived at that
certain degree of moisture which is suited both to its production and
vegetation. When further extended to dry situations, its effects are
considerably more destructive to the timber on which it subsists: here
it is very fibrous, and in part covered with a light brown membrane,
perfectly soft and smooth. It is often of much greater magnitude,
projecting from the timber in a white spongeous excrescence, on the
surfaces of which a profuse humidity is frequently observed: at other
times, it consists only of a fibrous and thin-coated web irregularly on
the surface of the wood. Excrescences of a fungiform appearance are often
protruded amidst those already described, and are evidences of a very
corrupt matter peculiar to the spots whence they spring. According to the
situation and matter in which they are produced, they are dry and tough,
or wet, soft, and fleshy, sometimes arising in several fungiforms, each
above the other, without any distinction of stem; and when the matter
is differently corrupted, it not unfrequently generates the small acrid
mushroom.
Mr. McWilliam observes, “The fungi arising from oak timbers are generally
in clusters of from three to ten or twelve; while those from fir timber
are mostly in single plants: and these will continue to succeed each
other until the wood is quite exhausted.”
Damp is not only a cause of decay, but is essential to it; while, on the
other hand, absolute wet, especially at a low temperature, prevents it.
In ships this has been particularly remarked, for that part of the hold
of a ship which is constantly washed by the bilge-water is never affected
with dry rot. Neither is that side of the planking of a ship’s bottom
which is next the water found in a state of decay, even when the inside
is quite rotten, unless the rot has penetrated quite through the inside.
It matters little whether wet is applied to timber before or after
the erection of a building. Timber cannot resist the effect of what
must arise in either case; viz. heat and moisture, producing putrid
fermentation; for instance, in basement stories with damp under them,
dry timber is but little better than wet, for if it is dry it will soon
be wet; decay will only be delayed so long as the timbers are absorbing
sufficient moisture, therefore every situation that admits moisture is
the destruction of timber.
In a constancy and equality of temperature timber will endure for ages.
Sir Christopher Wren, in his letter to the Bishop of Rochester, inserted
in Wadman’s ‘History of Westminster Abbey,’ notices “That Venice and
Amsterdam being both founded on wooden piles immersed in water, would
fall if the constancy of the situation of those piles in the same element
and temperature did not prevent the timber from rotting.” Nothing is more
destructive to woodwork than _partial leaks_, for if it be kept _always
wet_ or _always dry_, its duration is of long continuance. It is recorded
that a pile was drawn up sound from a bridge on the Danube, that parted
the Austrian and Turkish dominions, which had been under water 1500 years.
The writer of an article on the decay of wood, in the ‘Encyclopædia
Britannica,’ 1855, observes, “If a post of wood be driven into the
ground, the decay will commence at the surface of the ground; if driven
into the earth through water, the decay will commence at the surface of
the water; if used as a beam let into a damp wall, rot will commence just
where the wood enters the wall.”
Humboldt observes in his ‘Cosmos,’ with reference to damp and damp rooms,
that anyone can ascertain whether a room is damp or not, by placing a
weighed quantity of fresh lime in an open vessel in the room, and leaving
it there for twenty-four hours, carefully closing the windows and doors.
At the end of the twenty-four hours the lime should be reweighed, and if
the increase exceeds one per cent. of the original weight, it is not safe
to live in the room.
Decay of timber will arise from the effects of continued dryness or
continued wetness, under certain conditions; or it may also arise from
the effect of alternate dryness and moisture, or continued moisture with
heat.
At one time dry rot appears to have made great havoc amongst the wooden
ships of the British Navy. In the Memoirs of Pepys, who was Secretary to
the Admiralty during the reigns of Charles II. and James II., reference
is made to a Commission which was appointed to inquire into the state of
the navy, and from which it appears that thirty ships, called new ships,
“for want of proper care and attention, had toadstools growing in their
holds as big as one’s fists, and were in so complete a state of decay,
that some of the planks had dropped from their sides.”
In the ‘European Magazine’ for December, 1811, it is stated that, “about
1798, there was, at Woolwich, a ship in so bad a state that the deck
sunk with a man’s weight, and the orange and brown coloured fungi were
hanging, in the shape of inverted cones, from deck to deck.”
Mr. William Chapman, in his ‘Preservation of Timber from Premature
Decay,’ &c., gives several instances of the rapid decay of the ships
of the Royal Navy, about the commencement of the present century. He
mentions three ships of 74 guns each, decayed in five years; three of
74 guns each, decayed in seven years; and one of 100 guns, decayed in
six years. Mr. Pering, also, in his ‘Brief Enquiry into the Causes of
Premature Decay,’ &c., says that ships of war are useless in five or
six years; and he estimates the average duration to be eight years, and
that the cost of the hull alone of a three-decker was nearly 100,000_l._
Mr. Pering was formerly at the dockyard, Plymouth, and therefore a good
authority, if he availed himself of the opportunities of studying the
subject. He has stated that he has seen fungi growing so strong betwixt
the timbers in a man-of-war, as to force a plank from the ship’s side
half an inch.
No doubt a great deal of this decay was attributable to the use of
unseasoned timber, and defective ventilation; but there is too much
reason to believe that it was principally owing to the introduction
of an inferior species of oak (_Quercus sessiliflora_) into the naval
dockyards, where, we imagine, the distinction was not even suspected. The
true old English oak (_Quercus robur_) affords a close-grained, firm,
solid timber, rarely subject to rot; the other is more loose and sappy,
very liable to rot, and not half so durable.
One cause of the decay of wood in ships is the use of wooden treenails.
A treenail is a piece of cleft wood (made round), from 1 foot to 3
feet 6 inches in length and 1½ inch in diameter. As the treenails are
also made to drive easy, they never fill the holes they are driven
into; consequently, if ever it admits water at the outer end, which,
from shrinking, it is liable to do, that water immediately gets into
the middle of the plank, and thereby forms a natural vehicle for the
conveyance of water. The treenail is also the second thing which decays
in a ship, the first, generally, being the oakum. Should any part of
the plank or timbers of a ship be in an incipient state of decay, and a
treenail come in contact with it, the decay immediately increases, while
every treenail shares the same fate, and the natural consequence is, the
ship is soon left without a fastening. Treenails in a warm country are
sure to shrink and admit water.
Mr. Fincham, formerly Principal Builder in Her Majesty’s dockyard,
Chatham, considers that the destruction of timber by the decay commonly
known as dry rot, cannot occur unless air, (?) moisture, and heat are
all present, and that the entire exclusion of any of the three stays the
mischief. By way of experiment, he bored a hole in one of the timbers of
an old ship built of oak, whose wood was at the time perfectly sound;
the admission of air, the third element, to the central part of the wood
(the two others being to a certain degree present) caused the hole to be
filled up in the course of twenty-four hours with mouldiness, which very
speedily became so compact as to admit of being withdrawn like a stick.
The confinement of timber under most circumstances is attended with the
worst consequences, yet a partial ventilation tends to fan the flame of
decay.
The admission of air has long been considered the only means of
destroying the fungus, but as it has frequently proved ineffectual, it
must not be always taken as a certain remedy. If dry air be properly
admitted, in a quantity adequate to absorb the moisture, it will
necessarily exhaust and destroy the fungus; but care should be taken lest
the air should be conveyed into other parts of the building, for, after
disengaging itself from the fungus over which it has passed, it carries
with it innumerable seeds of the disease, and destroys everything which
offers a bar to its progress. Air, in passing through damps, will partake
of their humidity; it therefore soon becomes inadequate to the task for
which it is designed. Owing to this circumstance, air has been frequently
admitted into the affected parts of a building without any ultimate
success; too often, instead of injuring the fungus, it has considerably
assisted its vegetation, and infected with the disease other parts of the
building, which would otherwise probably have remained without injury.
The timber, which is in a state of decomposition by an intestinal decay,
is little affected by the application of air, as this cannot penetrate
the surrounding spongeous rottenness which generally forms the exterior
of such timber, and protects the action which the humid particles have
acquired in the exterior: as the extent and progress of the disease
is therefore necessarily concealed, it is difficult to ascertain
correctly the effect produced by the admission of dry air. Under these
circumstances of necessity and danger, it will require considerable
skill to effect the purpose without increasing the disease, and, as each
case has its own peculiar characteristics, it is necessary before one
attempts to admit air as a remedy, to previously estimate the destructive
consequences which may result from so doing, and ascertain whether it
will be injurious or beneficial to the building. The joists of the houses
built by our ancestors last almost for ever, because they are in contact
with an air which is continually changing. Now, on the contrary, we
foolishly enclose them between a ceiling of plaster (always very damp to
begin with) and a floor; they frequently decay, and then cause the most
serious disasters, of which it is impossible to be forewarned.
Damp, combined with warmth, is as a destroying agent, still more active
than simple damp alone--the heat being understood as insufficient to
carry off the moisture by evaporation; and the higher the temperature
with a corresponding degree of moisture, the more rapid the decay. If
the temperature to which wood is exposed, whilst any sap remains in
it, is too elevated, the vegetable fluids ferment; the tenacity is
diminished, and when the action is carried to its full extent, the wood
quickly becomes affected by the dry rot. Exposure to the atmosphere in
positions where rain can lodge in quantity, contact with the ground, and
application in damp situations deprived of air, will render wood liable
to the wet rot; and however well seasoned it may have been previously
to being brought within the influence of any of these causes, it will
infallibly suffer. Air should therefore have free access to the wood in
every direction:
… “for without in the wall of the house he made narrowed rests
round about, that the beams should not be fastened in the walls
of the house.”--1 Kings vi. 6.
Rondelet says, “The woodwork of the church of St. Paul, outside the city
walls, which was destroyed by fire in 1823, was erected as far back as
the fifth century.” Although the atmosphere surrounding the framework
was often at once warm and damp, yet it was never stagnant. It should be
remembered that 500 people in a church during two hours give off fifteen
gallons of water into the air, which, if not carried away, saturates
everything in the building after it has been breathed over and over
again in conjunction with the impurities it contains collected from each
individual.
Fever, scrofula, and consumption arise in many instances from defective
ventilation.
The signs of decay in timber are, as has been stated, fungi. Some of them
now and then are microscopic, and owe their existence to the sporules
deposited on the surface; while fermentation, generated by prolonged
contact with warm, damp, and stagnant air, is as a soil where seeds sow
and nourish themselves.
Mr. McWilliam, in his work on dry rot, states that if the temperature
be very low or very high, the effects are the same with respect to the
growth of fungi. At 80° dry rot will proceed rapidly, at 90° its progress
is more slow; at 100° it is slower still, and from 110° to 120° it will
in general be arrested. It will proceed fast at 50°; it may be generated
at 40°; its progress will be slow at 36°; and is arrested at 32°, yet it
will return if the temperature is raised to 50°.
Dry rot externally first makes its appearance as a mildew, or rather
a delicate white vegetation, that looks like such. The next step is a
collecting together of the fibres of the vegetation into a more decided
form, somewhat like hoar frost; after which it speedily assumes the
leathery, compact character of the fungus, forming into leaves, spreading
rapidly in all directions, and over all materials, and frequently
ascending the walls to a considerable height, the colour variable--white,
greyish white, and violet, light or decided brown, &c.
In the section of a piece of wood attacked by dry rot a microscope
reveals minute white threads spreading and ramifying throughout its
substance; these interlace and become matted together into a white
cottony texture, resembling lint, which effuses itself over the surface
of the timber; then in the centre of each considerable mass a gelatinous
substance forms, which becomes gradually of a yellow, tawny hue, and a
wrinkled, sinuated porous consistence, shedding a red powder (the spores)
upon a white down; this is the resupinate pileus, the hymenium being
upwards, of _Merulius lachrymans_, in its perfect and matured state. Long
before it attains to this, the whole interior of the wood on which it
is situated has perished; the sap vessels being gradually filled by the
cottony filaments of the fungus; no sooner do these appear externally
than examination proves that the apparently solid beam may be crumbled
to dust between the fingers; tenacity and weight are annihilated.
Dr. Haller says that seven parts in eight of a fungus in full vegetation
are found by analysis to be completely aqueous.
The strength of fungi is proportionate to the strength of the timber the
cohesive powers and nutritive juices of which they absorb; and according
to the food they receive so they are varied and modified in different
ways, and are not always alike. Different stages of corruption produce
food of different qualities, and hence many of the different appearances
of fungi. One takes the process of corruption up where another leaves it
off, and carries it forward and farther forward to positive putrefaction.
The forms which fungi assume are extremely diversified; in some instances
we have a distinct stem supporting a cap, and looking somewhat like a
parasol; in others the stem is entirely absent, and the cap is attached
either by its margin, and is said to be _dimidiate_, or by its back,
or that which is more commonly its upper surface, when it is called
_resupinate_. In some species the form is that of a cup, in others of
a goblet, a saucer, an ear, a bird’s nest, a horn, a bunch of coral, a
ball, a button, a rosette, a lump of jelly, or a piece of velvet.
Decomposition takes place without fungus where the timber and the
situation are always moist, as in a close-boarded kitchen floor, where
it is always dry, or very nearly so, and where it is alternately wet
and dry, cold and hot. When the decomposition is affected with very
little moisture, and no fungus, the admission of air will generally
prevent further contamination; but where there is abundance of moisture,
rottenness, and fungus, a small quantity of air will hasten the
destruction of the building.
In timber which has been only superficially seasoned this disease is
produced internally, and has been known to convert the entire substance
of a beam, excepting only the external inch or two of thickness to
which the seasoning had penetrated, into a fine, white, and threadlike
vegetation, uniting in a thick fungous coat at the ends, the semblance
being that of a perfectly sound beam. In this internal rot a spongy
fungous substance is formed between the fibres. This has often been
observed in large girders of yellow fir, which have appeared sound on
the outside, but by removing some of the binding joists have been found
completely rotten at the heart. An instance of this kind occurred at
Kenwood (the seat of the Earl of Mansfield) in 1815. Major Jones, R.E.,
states that on one occasion he was called upon to report on the state of
a building in Malta; that the timbers had every external appearance of
being sound, but on being bored with an auger they were found internally
in a total state of decay. It is on this account that the practice of
sawing and bolting beams is recommended, for when timber is large enough
to be laid open in the centre this part is laid open to season; so that
when a tree is large enough to be cut through to make two or more beams,
decomposition is impeded.
The first symptoms of rottenness in timber are swelling, discoloration,
and mouldiness, accompanied with a musty smell; in its greater advance
the fibres are found to shrink lengthways and break, presenting many deep
fissures across the wood; the fibres crumble readily to a fine snuff-like
powder, but retain, when undisturbed, much of their natural appearance.
In whatever way boughs are removed from trees, the effect of their
removal is, however, very frequently to produce a rotting of the inner
wood, which indicates itself externally by a sudden abnormal swelling of
the trunk a little above the root; sometimes the trunk becomes hollow at
the part affected, and this particular description of rot will almost
invariably be found to exist in those trees whose roots are much exposed.
The rot itself is either of a red, black, or white colour in the timber
when felled, and when either of the two last-named colours prevail, it
will be found that the decay does not extend very far into the tree;
but if, on the contrary, the colour of the parts most visibly affected
should be decidedly red, the wood should be rejected for any building
purposes. Sometimes small brown spots, indicative of a commencement of
decay, may be observed near the butt or root end of trees, and though
they do not appear to be connected with any serious immediate danger to
the durability of the wood, it is advisable to employ the material so
affected only in positions where it would not be confined in anything
like a close, damp atmosphere.
Great hesitation may be admitted as to the use of timber which presents
large bands of what are supposed to be indefinitely-marked annual
growth, because the existence of zones of wood so affected may be
considered to indicate that the tree was not in a healthy state when they
were formed, and that the wood then secreted lacked some of the elements
required for its durability, upon being subsequently exposed to the
ordinary causes of decay.
In many cases when timber trees are cut down and converted for use, it
is found that at the junction of some of the minor branches with the
main stem, the roots, as it were, of the branches traverse the surface
wood in the form of knots, and that they often assume a commencement of
decay, which in the course of time will extend to the wood around them.
This decay seems to have arisen in the majority of cases from the sudden
disruption of the branch close to its roots, with an irregular fracture,
and with such depressions below the surface as to allow the sap to
accumulate, or atmospheric moisture to lodge in them. A decomposition of
the sap takes place--in fact, a wound is made in the tree-and what are
called “druxy knots” are thus formed, which have a contagious action on
the healthy wood near them.
There is this particular danger about the dry rot; viz. that the germs
of the fungi producing it are carried easily, and in all directions, in
a building wherein it once displays itself, without necessity for actual
contact between the affected or the sound wood; whereas the communication
of the disease resulting from the putrefactive fermentation, or the wet
rot, only takes place by actual contact.
[Illustration: _Timber Beams,--rotten at the heart._]
Before dry rot has time to destroy the principal timbers in a building,
it penetrates behind the skirtings, dadoes, and wainscotings, drawing
in the edges of the boards, and splitting them both horizontally and
vertically. When the fungus is taken off, they exhibit an appearance
similar both in back and front to wood which has been charred; a light
pressure with the hand will break them asunder, even though affected with
the rot but a short time; and in taking down the wainscot, the fibrous
and thin-coated fungus will generally be seen closely attached to the
decayed wood. In timber of moderate length the fungus becomes larger and
more destructive, in consequence of the matter congenial to its growth
affording a more plentiful supply.
It is a great characteristic of fungi in general that they are very
rapid in growth, and rapid in decay. In a night a puff-ball will grow
prodigiously, and in the same short period a mass of paste may be covered
with mould. In a few hours a gelatinous mass of _Reticularia_ will pass
into a bladder of dust, or a _Coprinus_ will be dripping into decay. Many
instances have been recorded of the rapidity of growth in fungi; it may
also be accepted as an axiom that they are in many instances equally as
rapid in decay.
In considering the liability of any particular description of foreign
timber to take the dry rot, attention must be paid to the circumstances
under which it is imported. Sometimes the timber is a long while coming
here, whilst at other times it is imported in a very short period. The
length of time consumed in the voyage has a great deal to do with its
likelihood of taking the rot: it may have a very favourable passage, or
a very wet one, and the ship is frequently, in some degree, affected
with the disease. It perhaps begins in the ship, and it may often be
seen between the timber or deals, when it will impregnate the wood to a
great depth. Whether it is inherent in the timber or not, of this we may
be certain, that where there is a fetid atmosphere it is sure to grow.
Canadian yellow wood pine timber is more subject to rot than Baltic or
Canadian red wood timber, although the latter will sometimes decay in
four or five years. Turpentine is a preventive against dry rot, and
Canadian timber is sometimes largely impregnated with it, especially the
red wood timber; the yellow wood is very subject to dry rot. Very few
cargoes of timber in the log arrive from Canada in which in one part or
other of nearly every log you will not see a beginning of the vegetation
of the rot. Sometimes it will show itself only by a few reddish,
discoloured spots, which, when scratched by the finger nail to the extent
of each spot, it will be seen that the texture of the timber to some
little depth is destroyed, and will be reduced to powder; and on these
spots a white fibre may generally be seen growing. If the timber has been
shipped in a dry condition, and the voyage has been a short one, there
may be a few logs without a spot; but generally speaking very few cargoes
arrive from Canada in which there are many logs of timber not affected.
But if the cargo has been shipped in a wet condition, and the voyage has
been a long one, then a white fibre will be seen growing over nearly
every part of the surface of every log; and in cargoes that have been so
shipped, all the logs of yellow pine, red pine, and of oak, are generally
more or less affected on the surface.
Nearly every deal of yellow pine that has been shipped in Canada in a
wet state, when it arrives here is also covered over with a network of
little white fibres, which are the dry rot in its incipient state. There
is no cargo, even that which is shipped in tolerably dry condition, in
which, upon its arriving here, may not be found some deals, with the
fungus beginning to vegetate on their surface. If they are deals that
have been floated down the rivers of America or Canada, and shipped in a
wet state, on their arrival here they are so covered with this network
of the fungus, that force is often necessary to separate one deal from
another, so strongly does the fungus occasion them to adhere. They grow
together again, as it were, after quitting the ship, while lying in the
barges, before being landed. Accordingly, if a cargo has arrived in a wet
condition, or late in the year, or if the rain falls on the deals before
they are landed, and they are then piled in the way in which Norwegian
and Swedish deals are piled, that is, flatways, in six months time, or
even less, the whole pile of deals become deeply affected with rot; so
that, whenever a flat surface of one deal is upon the flat surface of
another, the rot penetrates to the depth of ⅛ of an inch. Its progress
is then arrested by repiling the deals during very dry weather, and by
sweeping the surface of each deal before it is repiled: but the best way
is to pile the deals in the first instance upon their edges; by which
means the air circulates freely around them, the growth of the fungus
is arrested, and the necessity of repiling them prevented. If the ship
is built of good, sound, and well-seasoned oak, the rot would perhaps
not affect it, but in order to prevent its doing so, the precaution is
usually taken to scrape the surface as soon as the hold is clear of the
cargo of timber. Were the cargo not cleared, and the hold not ventilated,
a ship that was permanently exposed to this fungus would, no doubt, be
affected. It is easy, however, to prevent its extending by washing the
hold with any desiccating solution.
Anyone who wishes to know how timber is occasionally shipped to this
country should read the report of a trial, in the ‘Times,’ 22nd Feb.,
1875 (Harrison _v._ Willis), relative to a cargo of pitch pine shipped
from Sapelo, in the Isthmus of Darien, for Liverpool. This cargo,
however, never arrived at Liverpool: it was lost at sea.
The motto of the Worshipful Company of Shipwrights is, “Within the ark,
safe for ever.” We suggest it should be altered to, “Within the ark
_which is free from dry rot_, safe for ever.”
There are two descriptions of European deals very liable to take the dry
rot; viz. yellow Petersburgh deals, and yellow and white battens, from
Dram, in Norway. When Dram battens, which have been lying a long time in
bond in this country, have not been repiled in time, they have been found
as much affected with the dry rot as many Canadian deals; though this has
not happened in so short a time as has been sufficient to rot Canadian
deals. The fungus growing on the Petersburgh deals and Dram battens
has all the characteristics and effects of dry rot as exhibited in the
Canadian deals, the detection of dry rot being in most cases the same.
It should be remembered that white deal absorbs more water than yellow;
and yellow more water than red; and the quantity of water absorbed by
the white accounts for its more rapid decay in external situations; as
the greater the quantity of water absorbed the quicker is the timber
destroyed. Mr. John Lingard, in his work on timber (1842), states that he
has proved that 4½ oz. of water can be driven off from a small piece of
fir, weighing only 10 oz. when wet, which is nearly half. This timber was
on a saw-pit, and going to be put into a building.
The most general, and the most fatal cause of decay, viz. the wet rot,
has attracted less attention than the more startling, but less common
evils, the dry rot, and the destruction by insects.
Sir Thomas Deane, in 1849, related before the Institution of Civil
Engineers of Ireland, an extraordinary instance of the rapid decay of
timber from rot, which occurred in the church of the Holy Trinity at Cork.
On opening the floors under the pews, a most extraordinary appearance
presented itself. There were flat fungi of immense size and thickness,
some so large as almost to occupy a space equal to the size of a pew,
and from 1 to 3 inches thick. In other places fungi appeared, growing
with the ordinary dry rot, some of an unusual shape, in form like a
convolvulus, with stems of from a quarter to half an inch in diameter.
When first exposed, the whole was of a beautiful buff colour, and emitted
the usual smell of the dry-rot fungus.
During a great part of the time occupied in the repairs of the church,
the weather was very rainy. The arches of the vaults having been turned
before the roof was slated, the rain water saturated the partly decayed
oak beams. The flooring and joists, composed of fresh timber, were laid
on the vaulting before it was dry, coming in contact at the same time
with the old oak timber, which was abundantly supplied with the seeds of
decay, stimulated by moisture, the bad atmosphere of an ill-contrived
burial-place, and afterwards by heat from the stoves constantly in use.
All these circumstances account satisfactorily for the extraordinary and
rapid growth of the fungi.
Many instances might be mentioned of English oak being affected with
dry rot, under particular circumstances. There was a great deal at the
Duke of Devonshire’s, at Chiswick, about 60 years ago. Needy builders,
who work for contract, sometimes use American oak, and call it wainscot:
it is a bad substitute for wainscot, being very liable to warp and to
be affected with dry rot. “I know of one public building,” observed the
late Mr. Henry Warburton, M.P., “in which it has been introduced, and, I
suppose, paid for under that name.”
Another serious instance of the decay of timber from rot occurred some
time since in Old St. Pancras Church, London. When the dry rot made its
appearance, it spread with amazing rapidity. Sometimes in the course of a
night, a fungus of about the consistence of newly-fallen snow, and of a
yellowish-white unwholesome colour, would be found to have spread over a
considerable surface. The fungus was without shape, but in some cases it
rose to a height of 2, 3, or 4 inches above the planks or other surfaces
on which it grew. It could be cut with a knife, leaving a clear edge on
each side, and there did not seem to be any covering or membrane over
the outer or under surface. The smell of those matters was unpleasant,
and seemed like the concentration of the smell which had pervaded the
church for so long a time before; and, in a short time, beams, planks of
flooring, railings, &c., were reduced to rottenness: the colour changed,
and a heavy dark-brown dust fell, and represented the once solid timber.
On making an examination with a view of discovering the cause of the
attack, it was found that in the graveyard, near the church, there were
graves, and several vaults: there were also vaults in the inside of the
church. Most of them were filled, or nearly so, with water, which had run
from the overcrowded graves.
In the interior there were water-logged vaults, and the walls were
saturated with damp. It was also seen that from want of proper spouts
and drains, near the outer walls, the drip from the large pent roof had
fallen into the foundations. In this situation, when the window frames
were properly arranged, a drain dug round and from parts of the church,
and other alterations, which should long before have been made, were
completed, the dry rot vanished, and no more complaints of the foulness
of the air have since been heard.
We could quote many cases of rot which have been caused from the want of
proper drains and spouts. Architects should remember that the feet of
Gothic collar roofs have to bear the whole weight of the roof, and unless
well seasoned, and carefully protected from damp, leaks, &c., premature
decay and dry rot will be sure to occur. It is surprising what injury
leaks from gutters will sometimes do. In 1851, Professor T. L. Donaldson
stated that “a brestsummer of American timber was used some time since
at a house in London: after an expiration of three years cracks began to
appear in the front wall. A friend of mine, an architect, was called in
to find out the cause; and after examining different parts of the house,
was almost giving up his search in despair, when he thought he would have
the shop cornice removed and look at the brestsummer. He then discovered
that some water had been admitted by accident, and penetrating the
brestsummer, had caused it to rot, and crack the wall.”
Dry rot was found in the great dome of the Bank of England, London, as
originally built by Sir Robert Taylor: it also existed in the Society of
Arts building, in the Adelphi, London. It was also found in the domes of
the Panthéon, and Halle-au-Blé, Paris; but we hope there is no dry rot in
the dome of St. Paul’s Cathedral, London, which is constructed entirely
of timber, covered externally with lead.
The decayed state of a barn floor attacked by rot is thus described by
Mr. B. Johnson: “An oak barn floor which had been laid twelve years began
to shake upon the joists, and on examination was found to be quite rotten
in various parts. The planks, 2½ inches in thickness, were nearly eaten
through, except the outsides, which were glossy, and apparently without
blemish. The rotten wood was partly in the state of an impalpable powder,
of a snuff colour; other parts were black, and the rest clearly fungus.
No earth was near the wood.” This oak was probably of the _Quercus
sessiliflora_ species; and there was no ventilation to the floor.
Mr. John Armstrong, carpenter, employed for many years at Windsor Castle,
observed: “I was employed a few years back at a house where I found a
floor rotten. We took it up; it was yellow pine; it was laid in the
damp, but on sleepers, and the sleepers were not rotten: they were of a
different description of wood.” Probably the sleepers were of Baltic red
wood.
Dr. Carpenter relates an instance of the expansive power resulting
from the rapid growth of the soft cellular tissue of fungi. About the
commencement of this century the town of Basingstoke was paved; and not
many months afterwards the pavement was observed to exhibit an unevenness
which could not easily be accounted for. In a short time after, the
mystery was explained, for some of the heaviest stones were completely
lifted out of their beds by the growth of large toadstools beneath them.
One of these stones measured 22 inches by 21 inches, and weighed 83 lb.,
and the resistance afforded by the mortar which held it in its place
would probably be even a greater obstacle than the weight. A similar
incident came under the notice of Mr. M. C. Cooke (the author of ‘British
Fungi’), of a large kitchen hearthstone which was forced up from its bed
by an under-growing fungus, and had to be relaid two or three times,
until at last it reposed in peace, the old bed having been removed
to the depth of 6 inches, and a new foundation laid. A circumstance
recorded by Sir Joseph Banks is still more extraordinary, of a cask of
wine which, having been confined for three years in a cellar, was, at
the termination of that period, found to have leaked from the cask, and
vegetated in the form of immense fungi, which had filled the cellar, and
borne upwards the empty wine cask.
Timber decay in contact with stone is a subject deserving consideration.
This decay is entirely obviated by inserting the wood in an iron shoe,
or by placing a thin piece of iron between the wood and the stone. It is
said that a hard crust is formed on the timber in contact with the iron,
which seems effectually to preserve it; it is, of course, necessary that
a free circulation of air round the ends of the timber be provided. The
most notable instance of timber decay in contact with stone with which we
are acquainted occurred at the coronation of George IV. Westminster Hall
was then fitted up, and they began by laying sleepers of yellow pine. The
coronation was suspended for twelve months, and when the sleepers were
taken up from the floor of Westminster Hall, they were in a rotten state.
Timber in contact with brickwork is in Suffolk and in some parts of
England covered with sheet lead to preserve it from the effects of the
damp mortar. Fungi will arise in mortar, if made with road-drift, and
water from stagnant ponds, &c., and it may be traced through the mortar
joints, and will thus appear on both sides of a wall. Mortar composed of
unwashed sand will generate fungi; sea sand, even if washed, should never
be used. It is considered that the system of grouting contributes to the
early decay of timber; wood bond timber for walls has been consequently
replaced by hoop iron bond. In Manchester wood bond is frequently used,
and is said to answer well, but the high temperature of the buildings may
be a preventive against the decay of timber, as the walls are soon dried.
The practice is a bad one.
When timber used as posts inserted in the ground is placed in the
inverted position to that in which it stood when growing, it is said
to be very much more durable than if placed in its natural or growing
position. This is easily accounted for in the valves of the sap vessels
of the growing timber opening upwards; but when that position is
inverted, the valves of the sap vessels become reversed in their action;
and, therefore, when timber is used as posts inserted in the ground, the
valves being so reversed prevent the ascent of moisture from the soil in
the wood. Mr. W. Howe relates an experiment made to test the comparative
durability of posts set as they grew. He says, “Sixteen years ago I set
six pairs of bar posts all split out of the butt end of the same white
oak log. One pair I set butts down; another pair, one butt down, the
other top down; the others top down. Four years ago those set butt down
were all rotted off, and had to be replaced by new ones. This summer I
had occasion to reset those that were set top down: I found them all
sound enough to reset. My experiments have convinced me that the best
way is to set them tops down.” Other instances might be given in favour
of placing posts in an inverted position in the ground. Posts will
sometimes decay, for the following reason: The ends are often sawn off
with a coarse implement and left spongy, with the longitudinal fibres
shaken or broken a considerable way within the extremity of the wood. In
this state the ends of the posts must be apt to absorb from the ground
the moisture, which, being retained, and speedily pervading the whole
internal surface, _especially if painted_, appears to cause decay.
With respect to the preservation of wooden fences, Mr. Cruikshank, of
Marcassie, gives in detail various experiments from which it appears
that--1st. When larch or pine wood is to be exposed to the weather, or
to be put in the ground, no bark should be left on. 2nd. When posts are
to be put in the ground, no earth should be put round them, but stones.
3rd. When a wooden fence is to be put up, a No. 4 or No. 5 wire should be
stretched in place of, or alongside the upper rail.
Mr. G. S. Hartig, in the ‘Revue Horticole,’ gives the results of
experiments made with great care and patience, upon woods buried
in the earth. Pieces of wood of various kinds 3⅛th inches square,
were buried about one inch below the surface of the ground, and they
decayed in the following order: the lime, American birch, alder,
and the trembling-leaved poplar, in three years; the common willow,
horse-chestnut, and plane, in four years; the maple, red beech, and
common birch, in five years; the elm, ash, hornbeam, and Lombardy
poplar, in six years; the oak, Scotch fir, Weymouth pine, and silver
fir, were only decayed to the depth of half an inch in seven years;
the larch, common juniper, red cedar, and arbor vitæ, at the end of
the last-mentioned period remained uninjured. The duration of their
respective woods greatly depends on their age and quality; specimens from
young trees decaying much quicker than those from sound old trees; and,
when well seasoned, they, of course, last much longer than when buried in
an unseasoned state. In experiments with the woods cut into thin boards,
decay proceeded in the following order: the plane, horse-chestnut,
poplar, American birch, red beech, hornbeam, alder, ash, maple, silver
fir, Scotch fir, elm, Weymouth pine, larch, locust oak.
Before quitting the subject of decay of timber when buried in the earth,
it will not be out of place to allude to the decay of railway sleepers,
taking for example those in India: English and American sleepers will be
dealt with more in detail hereafter.
Dr. Cleghorn, Conservator of Forests, Madras Presidency, India, considers
the decay of sleepers to arise in a great measure from the inferior
description of wood used. Mr. Bryce McMaster, Resident Engineer,
Salem, considers that the native wood sleepers in India have hitherto
been found for the most part to fail on the Madras Railway, between
30 and 40 per cent. requiring to be renewed annually. Mr. McMaster
undertook an investigation with a view of ascertaining the causes of
this deterioration, and whether those causes could be overcome so as to
render available the vast resources of India. Thirteen hundred sleepers
of sixteen different woods were submitted to careful examination and
scrutiny twice at an interval of one year. The sleepers were variously
placed, both on embankments and in cuttings; in some cases they were
entirely covered with ballast to a depth of 4 inches; while in others
they were as much as possible uncovered, and completely so from the rails
to the ends--the ballast being only raised 2 inches in the middle of
the way, and sloped off so as to carry away the water under the rails.
From these observations it appeared that only five woods, Chella wungé,
Kara mardá, Palai, Karúvalem, and Ilupé, were sound at the end of two
years, the other eleven not lasting even that time. Also, that when the
sleepers were uncovered, decay was less rapid than when they were buried
in the ballast. The plan of leaving the sleepers partially uncovered had
many advantages; it effected a saving of the ballast, allowed the defects
to be more quickly detected, and kept the sleepers drier. It had been
urged that the heat of the sun would split the sleepers and cause the
keys and treenails to shrink; but from experience it was found that while
among the “uncovered” sleepers there was a large proportion “beginning
to split,” or “useless from being split,” there was on the other hand,
among the “covered” sleepers, a still larger proportion “beginning to
rot,” or “useless from being rotten.” It was also noticed that of the
sleepers “beginning to rot,” 19 per cent. had commenced under one or
both chairs. This was due to the retention of moisture under them, and
might be remedied by tarring the seats of the chairs. As regarded the
treenails where the sleepers were rotten, the treenails were invariably
found to be in the same state; while, when the heads were exposed to the
sun, they were not loosened by shrinking. Another objection was, that the
road would be more likely to buckle and twist, but this was not found in
practice to be the case. Treenails made in India cost 2_l._ 10_s._ to
4_l._ per 1000, and the woods generally used for the purpose are Vengé,
Kara mardá, Erul, Porasa, or satin wood, and Trincomalee. The three
woods first named are also extensively employed for keys, but teak keys
seem to be the best, and their cost does not exceed 6_l._ per 1000. From
the experience of the Indian engineers it appears that Teak, Saul, Sisso,
Pedowk, Kara mardá, Acha, Vengé, Chella wungé, Palai, Erul, Karúvalem,
will make very good sleepers to be used plain.
The sleepers which have failed on the Madras Railway might well be
divided into two classes,--those which were originally of perishable
woods, and were therefore unfit for the purpose; and those which although
of good wood had been cut from young trees, and not been allowed to
stand until old enough. The first arose from want of experience of the
nature of Indian woods: the second from the absence of a proper system of
working the jungles.
The wooden sleepers on the Indian railways should be tarred under the
seats of the chairs, be laid in dry ballast, and raised slightly in the
middle, and sloped off so as to throw the water under the rails. About
two-thirds of the Indian woods are practically useless owing to the want
of proper artificial means for preserving those of a perishable nature.
The subject of the decay of wood in India and tropical climates is too
extensive to be further considered here; but is of sufficient importance
to demand a volume to itself; the renewal of decayed wooden sleepers
to railways forming annually a most important item in foreign railway
budgets.
We have heard that some of our fortifications which have been erected
within the last few years to protect our English coast from invasion,
have already been invaded by dry rot. If this be true, some one well
acquainted with the subject should at once be appointed to find out the
cause, and recommend the remedy in each case.
Professional men, if they wish their works to “live for ever,” should
consider the after consequences of neglecting to provide against dry
rot. If the fungi could speak from under floors, ceiled-up roofs, behind
wainscots, girders, &c., we should often hear them exclaim, “A nice moist
piece of wood! Surely this belongs to us.” On the beams of a building at
Crawley, a carpenter many years ago cut a few words; they are full of
meaning in connection with our subject, and they run as follows:
“Man of weal, beware; beware before of what cometh behind.”
CHAPTER III.
FELLING TIMBER.
The end to be attained in the management of timber trees is to produce
from a given number the largest possible amount of sound and durable
woods. When a tree, under conditions favourable to its growth, ceases
increasing the diameter of its trunk, and loses its foliage earlier in
the autumn than it is wont to do, and when the top of the tree brings
forth no leaves in spring, these facts may be considered as indications
of decline, and that the tree is of sufficient age to be felled. The
state of the upper branches of a tree may be considered to be amongst
the best indications of its soundness, and provided they be in a
healthy condition, the withering of the lower branches is a matter of
comparatively small importance.
Trees may be considered as tall, middle rank, and low, and the size
to which they will attain depends on many different circumstances.
Some trees, the stems of which are short on the average, as the lime,
are virtually of tall growth, from the manner in which a number of
vertical branches of large size ascend from the stem. And other trees,
again, whose branches are comparatively short, are of tall growth, in
consequence of the length of the stems--like the beech.
The average duration of trees differs, as is well known, in different
species, and they exhibit different symptoms of decay. There are oaks in
Windsor Great Park, certainly nearly one thousand years old, and which
exhibit even now no appearance of approaching the end of their life. Mr.
Menzies, the surveyor, in his work on Windsor Great Park, describes some
of the indications of incipient decay which are peculiar to the several
kinds of trees. “When a beech begins to fail,” he says, “fungi appear
either at the roots or on the forks, the leaves curl up as if they had
been scorched, and the tree quickly perishes. In an elm, a great limb
first fails, while the rest of the tree continues green and vigorous,
but in a few years the whole tree suddenly dies. Coniferous trees die
gradually, but quickly. The oak shows the first symptoms at the points
of its highest branches, while the rest of the tree will remain healthy
and sound for years.” This peculiarity of the oak did not escape the eye
of Shakespere, that universal observer, who describes the monarch of the
woods as not only having its boughs mossed with age, but its
“High top bald with dry antiquity.”
The age for felling trees is a subject which calls for the deepest
consideration, but does not always receive that attention which is due
to its importance. Timber growers in their haste to supply the market,
too often fell trees that have not arrived at maturity, the heart-wood
being therefore imperfect, with much sap-wood, and, of course, little
durability; but unfortunately they are the more readily led to do so
on account of the increase in size being very slow after a certain
age. Builders are sensible of the inferior quality of young timber in
respect to duration, and it is their province to check this growing evil,
by giving a better price for timber that has acquired a proper degree
of density and hardness; but, unfortunately, this is an age for cheap
building, without much regard being given as to durability.
Felling should not be too early, for the reasons above mentioned; neither
should it be in the decline of the tree, when its elasticity and vigour
are lost, and the wood becomes brittle, tainted, and discoloured, with
the pith gone, and the heart in progress of decay. Maturity is the period
when the sap-wood bears a small proportion, and the heart-wood has become
uniform and compact. Sir John Evelyn writes, “It should be in the vigour
and perfection of trees, that a felling should be celebrated.” It must
be obvious, however, that it is a worse fault to fell wood before it has
acquired thorough firmness, than when it is just in the wane, and its
heart may exhibit but the first symptoms of decay; for in the former
there is no perfect enduring timber to be got, while in the latter the
greater part is in the zenith of its strength.
Although there are certain symptoms by which it may be ascertained when
a tree is on the decline, it is somewhat difficult to decide just when a
tree is at maturity. From the investigations of naturalists, however, it
may be safe to consider that hard-wood trees, as oak and chestnut, should
never be cut before they are sixty years old, the average age for felling
being from eighty to ninety years, and the average quantity of timber
produced by a tree of that age is about a load and a half, or about 75
cubic feet.
Daviller states (see ‘Cours d’Architecture’) “that an oak should not be
felled at a less age than sixty years.” Belidor considers (see ‘Sciences
des Ingénieurs’) “that one hundred years is the best age for the oak to
be felled.”
It should be remembered that the times mentioned are by no means
arbitrary, for situation, soil, &c., have much to do with it. For the
soft woods, as the Norway spruce and Scotch pine in Norway, the proper
age is between seventy and one hundred years. The ash, larch, and elm,
may be cut when the trees are between fifty and ninety years old; and
between thirty and fifty years is a proper age for poplars.
The felling of timber was looked upon by ancient architects as a matter
of much moment. According to Vitruvius, the proper time for felling is
between October and February, and he directs that the trees should be cut
to the pith, and then suffered to remain till the sap be drained out. The
effusion of the sap prevents the decay of the timber, and when it is all
drained out, and the wood becomes dry, the trees are to be cut down, when
the wood will be excellent for use. A similar effect might be produced
by placing the timber on its end as soon as it is felled, and it would,
no doubt, compensate for the extra expense by its durability in use. In
France, so long ago as 1669, a royal order limited the felling of naval
timber from the 1st October to 15th April, when the “wind was at north,”
and “in the wane of the moon.” Buonaparte directed that the time for
felling naval timber should be “in the decrease of the moon, from 1st
November to 15th March,” in order to render it more durable. In England,
in the first year of James I., there was an Act of Parliament prohibiting
every one from cutting oak timber, except in the barking season, under a
severe penalty.
James I. was not the only English sovereign who has been concerned with
timber trees; for King John was obliged to cancel at Runnemede the cruel
forest laws enacted by his father, William the Conqueror, especially
those restricting the people from fattening their hogs.
Up to a recent period large droves of hogs were fattened upon the
acorns of the New Forest in Hampshire. At the present time the hogs of
Estremadura are principally fed upon the acorns of the _Ballota_ oak; and
to this cause is assigned the great delicacy of their flesh.
A Berkshire labourer, living near Windsor Forest, thus speaks of the
delicacy of acorn-fed pork: “Well, that be pretty like the thing. I
hadn’t tasted the like o’ that this many a day. It is so meller--when you
gets your teeth on it, you thinks you has it; but afore you knows where
you is, ain’t it wanished!”
There is another point in connection with the time of felling timber,
which ought to be noticed. It is a widespread opinion that trees should
be felled during the wane of the moon. This planetary influence is open
to doubt, but the opinion prevails wherever there are large forests.
Columella, Cato, Vitruvius, and Pliny, all had their notions of cutting
timber at certain ages of the moon. The wood-cutters of South America act
upon it, so do their brethren in the German forests, in Brazil, and in
Yucatan. It was formerly interwoven in the Forest Code of France, and,
we believe, is so still. Vitruvius recommends this custom, and we find
Isaac Ware writing of the suggestion: “This has been laughed at, and
supposed to be an imaginary advantage. There may be good in following
the practice; there can be no harm: and therefore, when I am to depend
upon my timber, I will observe it.” The Indian wood-cutters believe that
timber is much more liable to decay, if cut when the moon is in crescent.
An American writer, in 1863, thus writes of his experience in the matter:
“Tradition says that the ‘old’ of the moon, in February, is the best
time to cut timber; but from more than twenty years of observation and
actual experience, I am fully convinced it is about the worst time to cut
most, if not all kinds of hard-wood timber. Birch, ash, and most or all
kinds of hard wood will invariably _powder-post_ if cut any time in the
fall after the tree is frozen, or before it is thoroughly leaved out in
the spring of the year. But if cut after the sap in the tree is used up
in the growth of the tree, until freezing weather again comes, it will
in no instance produce the _powder-post_ worm. When the tree is frozen,
and cut in this condition, the worm first commences its ravages on the
inside film of the bark, and then penetrates the wood until it destroys
the sap part thereof. I have found the months of August, September, and
October, to be the three best in the year to cut hard-wood timber. If cut
in these months, the timber is harder, more elastic, and durable than if
cut in winter months. I have, by weighing timber, found that of equal
quality got out for joiners’ tools is much heavier when cut and got out
in the above-named months than in the winter and spring months, and it
is not so liable to crack. You may cut a tree in September, and another
in the ‘old’ of the moon in February following, and let them remain, and
in one year from the cutting of the first tree, you will find it sound
and unhurt, while the one last cut is scarcely fit for firewood, from
decay. Chestnut timber for building will last longest, provided the bark
be taken off. Hemlock and pine ought to be cut before being hard frozen,
although they do not _powder-post_; yet if they are cut in the middle
of winter, or in the spring of the year, and the bark is not taken off,
the grub will immediately commence its ravages between the bark and the
wood. I have walnut timber on hand which has been cut from one to ten
years, with the bark on, which was designed for ox-helves and ox-bows,
and not a worm is to be found therein; it was cut between 1st August and
1st November. I have other pieces of similar timber cut in the winter
months, not two year’s old, and they are entirely destroyed, being full
of _powder-post_ and grub-worms.”
What shall we say when doctors disagree? The theory given to account for
what is assumed to be a fact, is, that as the moon grows the sap rises,
and the wood, therefore is less dense than when the moon is waning,
because at that time the sap in the tree diminishes. No evidence whatever
can be offered in support of the theory, and one would certainly imagine
that the rise or fall of the sap would depend on the quantity of heat
which reaches the foot of the tree, and not at all on attraction.
All investigations tend to prove that the only proper time for felling
timber is that at which the tree contains the least sap. There are two
seasons in each year when the vessels are filled. One is in spring, when
the fluid is in motion to supply nutriment to the leaves, and deposit
material for new wood; the other is in the early part of autumn, when,
after the stagnation which gives the new wood time to dry and harden, it
again flows to make the vegetable deposits in the vessels of the wood.
At neither of these times should trees be felled; for, if the pores be
full of vegetable juices, which being acted upon by heat and moisture may
ferment, the wood will decay. Of the two periods, the spring must be the
worst, because the wood then contains the greatest quantity of matter in
a state fit for germination.
The results of a series of experiments made in Germany show that
December-cut wood allows no water to pass through it longitudinally;
January-cut wood passed in forty-eight hours a few drops; February-cut
wood let two quarts of water through its interstitial spaces in
forty-eight hours; March-cut wood permitted the same to filter through in
two and a half hours. Hence the reasons why barrels made from wood cut in
March or April are so leaky, as the sap is then rising, and the trees are
preparing to put forth their leaves.
It thus happens that the time for felling is midsummer or midwinter. The
best time for felling, according to some, is midsummer, when the leaves
are fully expanded, and the sap has ceased to flow, and the extraneous
vegetable matter intended for the leaves has been dislodged from the
trunk of the tree by the common sap, leaving it in a quiescent state,
and free from that germinative principle which is readily excited by
heat and moisture, and if the timber were cut while it remained, would
subject it to rapid decay and to operations of worms. Midwinter, amongst
some, is chosen as a time for felling, as it is stated that winter-felled
heart-wood is less affected by moisture, and likely to be the best and
most durable; but as the only peculiar recommendation which that time
possesses is the facility which it affords for gradual seasoning, by
which timber is rendered less liable to split and get distorted, and
slow drying being generally available at any season under shade and
shelter, midsummer appears for many obvious reasons the most expedient.
In general, all the soft woods, such as elm, lime, poplar, willow,
should be felled during winter. In some kinds of trees a little after
midsummer appears to be decidedly the best time for felling. Alder felled
at that time is found to be much more durable; and Ellis observes, that
beech when cut in the middle of summer is bitter, and less liable to be
worm-eaten, particularly if a gash be cut to let out the sap some time
before felling. Mr. Knowles states that, “About Naples, and in other
parts of Italy, oaks have been felled in summer, and are said to have
been very durable.” Most of the trees in southern Italy are felled in
July and August, and the pines in the German forests are cut down mostly
in summer time, and it is stated that their wood is sound.
The following are advocates for winter felling, viz. Cato, Pliny,
Vitruvius, Alberti, Hesiod, De Saussure, Evelyn, Darwin, and Buonaparte.
Some of them consider that winter-felled timber, which has been barked
and notched in the previous spring, loses much of that half-prepared
woody matter, containing seeds of fungi, &c., that there is no doubt of
its superiority to summer-felled timber.
The age at which trees should be felled, and the most suitable time for
the work having been determined, there are two other things which claim
attention.
The _first_ of these is the removal of the bark from the trunk and
principal branches of the tree. For, in oak trees, the bark is too
valuable to be lost; and as the best period for the timber is the worst
for the bark, an ingenious method has been long partially practised,
which not only secures the bark at the best season, but also materially
improves the timber. This method consists in taking the bark off the
standing tree early in the spring, and not felling it till after the
new foliage has put forth and died. This practice has been considered
of inestimable value; for by it the sap-wood is rendered as strong and
durable as the heart-wood; and in some particular instances experiments
have shown it to be four times as strong as other wood in all respects
similar, and grown on the same soil, but felled with the bark on and
dried in sheds. Buffon, Du Hamel, and, in fact, most naturalists, have
earnestly recommended the practice. Evelyn states, “To make excellent
boards, bark your trees in a fit season, and let them stand naked a full
year before felling.”
In regard to the time that should elapse between the removal of the bark
and the felling of a tree, a variety of opinions exist. It was the usual
custom of early architects to remove the bark in the spring, and fell the
trees during the succeeding winter. Later investigations seemed to have
proved that it is better to perform the work three or even four years in
advance, instead of one, although Tredgold appears to think one year too
long. Trees will, in most situations, continue to expand and leaf out for
several seasons after the bark has been removed. The sap remaining in the
wood gradually becomes hardened into woody substance, thereby closing
the sap vessels and making it more solid. As bark separates freely from
the wood in spring, while the sap is in motion, it should be taken off
at that period. When the above method is not adopted, it is well either
to pierce the trunk some time before felling to drain out the sap, or
immediately on its being felled to set it on end.
The _second_ suggestion is, to cut into and around the entire trunk of
the tree, near the roots, so that the sap may be discharged; for in this
manner it will be done more easily than it can be by evaporation after
the tree is felled. In addition to this, if it be permitted to run out
at the incision, a large portion of the new and fermentable matter will
pass out with it, which would remain in the wood if only such material
is removed as would pass off by evaporation. This cutting should be made
in the winter previous to the August in which the tree is to be felled;
and the incision should be made as deep into the heart-wood as possible
without inducing a premature fall of the tree.
The custom of ringing or girdling the tree before felling has been
advocated, on the ground that the seasoning is thereby expedited,
and also more thoroughly effected. This is doubtful, at least, in
oil-containing trees (as teak, &c.), but the practice appears to be
contra-indicated for other reasons: when a tree has been ringed, many
wood-cutters object to cut it down on account of its increased hardness.
This objection might be waived, were it not for another and more serious
one which has been adduced. It is believed to be a fact by some that
trees felled after girdling have the heart shake increased. It is
difficult to explain this, if it be actually the case.
Many suggestions might be made as regards the mechanical operation of
felling trees, with which ancient nations were not unfamiliar:
… “for thou knowest that there is not among us any that can skill
to hew timber like unto the Sidonians.”--1 Kings v. 6.
But as these operations are familiar to all intelligent workmen, it
is only necessary to mention one, viz. the value of removing from the
side of the tree such branches as will strike the ground when it falls,
and, by wrenching, cleave the grain of the wood, and thereby injure the
timber. Such defects, which are often found after the timber has been
seasoned, could not be discovered when it left the mill.
In conclusion, we can truly state that the most extensive felling of
trees for _one building_ only which we have ever heard or read of is the
following:
“And Solomon had threescore and ten thousand that bare burdens,
and fourscore thousand hewers in the mountains.”--1 Kings v. 15.
CHAPTER IV.
ON SEASONING TIMBER BY NATURAL METHODS, VIZ. HOT AND COLD AIR; FRESH AND
SALT WATER; VAPOUR; SMOKE; STEAM; BOILING; CHARRING AND SCORCHING, ETC.
All timber must, whether it be sap-wood or heart-wood, be placed in
situations which will allow the sap to exude or evaporate, and this
process is the one technically known by the term “seasoning.” There are
natural and artificial modes of seasoning, both of which have their
recommendations; but the former has certainly the right of preference,
as it gives greater toughness, elasticity, and durability, and therefore
should always be employed in preparing timber for carpentry. As the word
“timber” has been frequently used, it may be as well to state that it is
derived, according to Dr. Johnson, from the Saxon, _timbrian_, to build:
hence the above definition. The legal definition of timber is restricted
to particular species of wood, and custom varies in different countries
as to the species ranked among the timber trees.
When a tree is felled, it encloses in its fibres as well as in capillary
channels a considerable quantity of sap, which is nothing else but water
charged with gummy, saccharine, saline, mucilaginous, and albuminous
matters. In this state, the latter are very liable to ferment, but they
lose their liability when, by the evaporation of the sap, they pass
to a dry and solid state; so that the first suggestion which naturally
presents itself to the mind, is to subject the timber to a lengthened
seasoning.
But the present demands for time will not admit of this, and therefore it
is imperative to resort to artificial and speedy methods.
With respect to the value of timber in the log, owing to its becoming
rent by the weather, it sells for 15 per cent. less the second year than
the first, and so on for less and less the longer you keep it.
A natural seasoning may be adopted for specimens of moderate thickness,
such as deals, planks, &c. At the end of eighteen months from the time of
importation they are scarcely dry enough for the consumer’s use.
When there is time for drying it gradually, all that is necessary to be
done on removing it from the damp ground of the forest, is to place it
in a dry yard, sheltered from the sun and wind, and where there is no
vegetation; and set it on bearers of iron or brick in such a manner as to
admit of a ventilation all round and under it. In this manner it should
continue two years, if intended for carpentry; and double that time,
if intended for joinery; the loss of weight which should take place to
render it fit for the purposes of the former being about one-fifth; and
for the latter about one-third. In piling it, the sleepers on which the
first pieces are laid should be perfectly level, and “out of the wind,”
and so firm and solid throughout that they will remain in their original
position; for timber, if bent or made to wind before it is seasoned,
will generally retain the same form when dried. Blocks of wood should
be put between the “sticks” of timber, and each piece directly over the
other, so that air may freely pass through the whole pile; for while it
is necessary to shield timber from strong draughts of wind and the direct
action of the hot sun, a free circulation of air and moderate warmth are
equally essential.
[Illustration: PLANS OF DIFFERENT BALTIC MODES OF CUTTING DEALS FOR THE
ENGLISH AND FRENCH MARKETS.
THE SMALLEST TREES ARE CUT FOR DEALS; THE LARGEST FOR LOGS.
OLD MODE OF CUTTING.
ENGLISH BATTEN. 7IN × 2½IN
ENGLISH DEAL. 9IN × 2½IN
ENGLISH DEAL. 9IN × 2½IN
ENGLISH BATTEN 7IN × 2½IN
9 × 2½ = 22½ × 2 = 45in
7 × 2½ = 17½ × 2 = 35/80
MODE PRACTISED UNTIL THE FRENCH MARKET IMPROVED.
ENGLISH BATTEN. 7IN × 2½IN
ENGLISH DEAL. 9IN × 3IN
ENGLISH BATTEN. 7IN × 2½IN
9 × 3 = 27 = 27in
7 × 2½ = 17½ × 2 = 35/62
MODE GENERALLY ADOPTED AT THE PRESENT TIME.
FRENCH DEAL. 9IN × 1¼IN
ENGLISH DEAL. 9IN × 3IN
ENGLISH DEAL. 9IN × 3IN
FRENCH DEAL. 9IN × 1¼IN
9 × 3 = 27 × 2 = 54in
9 × 1¼ = 11¼ × 2 = 22½/76½
_Notes on Deals._
_All deals are liable to dry rot, if placed in contact with damp
brickwork._
_If the pith of a tree be left in the centre of a deal, dry rot attacks
it._
_Dry rot first attacks the sapwood of a deal; and next, the pith._
_Stockholm, or Gefle deals are not liable to be affected with dry rot._
“STRONG” DEALS _rend. When sawn, they do not give saw dust, but the
fibres tear_.
BEST DEALS _are light, mellow, and exhibit a silky texture when planed_.
“BESTS”. _Wholly free from knots, shakes, sapwood, or cross grain, and
well seasoned._
“SECONDS”. _Free from shakes, and sapwood: small knots allowed._
“THIRDS”. _All that remains after “bests” and “seconds” have been picked
out._]
If timber is not used round, it is good to bore out the core; as, by so
doing, the drying is advanced, and splitting prevented, with almost no
sacrifice of strength. If it is to be squared into logs, it should be
done soon after some slow drying, and whole squared, if large enough, as
that removes much of the sap-wood, facilitates the drying, and prevents
splitting, which is apt to take place when it is in the round form, in
consequence of the sap-wood drying before the heart, from being less
dense. If it may be quartered, it is well to treat it so after some time,
as the seasoning is by that means rendered more equal. It is well also to
turn it now and then, as the evaporation is greatest from the upper side.
In France, the term “bois du brin,” means timber the whole size of the
tree, excepting that which is taken off to render it square.
To prevent timber warping to any serious extent, it should be well
seasoned before it is cut into scantlings; and the scantlings should be
cut some time before they are to be used, in order that the seasoning
may be as perfect as possible; and if they can be set upright, so much
the better, as then they will dry more rapidly. The white lowland deals
of Norway and the white spruce deals of Canada have the same disposition
to warp and split on drying. Du Hamel has shown that it is a great
advantage to set the timber upright, with the lower end raised a little
from the ground; but as this cannot always be done, the timber-yards
should be well drained and kept as dry as possible. “Ancient architects,”
observes Alberti, “not only prevented the access of the scorching rays of
the sun and the rude blasts of wind, but also covered the surface with
cow-dung, to prevent the too sudden evaporation from the surface.” The
warping of timber is attributable by some to the manner of its growth.
Boards cut out of a tree that is twisted in its growth will not keep
from warping; boards cut from trees that are grown in open situations
have another fault, in the heart of the tree not running straight like
forest-grown wood. In a plank cut from a tree of this kind in a straight
line, the heart will traverse it from one end to another. No treatment
will prevent it from warping or drying hollow on the side farthest from
the heart. Where the heart is in the centre of a plank, and each side has
an equal chance of drying, it will not warp; but there will be a shake or
crack upon each side, denoting the position of the heart.
Some deals, and particularly the stringy deals, are very hygrometric,
and never lose the property, however long they have been seasoned, of
expanding and contracting with change of weather. White Petersburgh deals
are said to have that property, however long they may have been kept,
so that if used in the panel of a door, the wood alternately enters and
recedes from the groove into which it fits, as the paint will show when
that kind of deal has been used for a panel.
The wood of the north side will not warp so much as the wood from the
south side. The face of the planks should be cut in the direction which
lay from east to west as the tree stood. If this be done, the planks will
warp much less than if cut in the opposite direction. The nature of the
tree, the soil upon which it is grown, the position of its growth, the
period of the year in which it is felled, and the length of time between
its felling and converting, are the principal points to be considered; a
thorough knowledge and study of which is the only true principle on which
we can hope to deal with the warping and converting of timber.
Wood, when it is cut into small pieces, very soon acquires its utmost
degree of dryness. Dr. Watson, Bishop of Llandaff, in the month of
March, cut a piece from the middle of a large ash tree that had been
felled about six weeks, and weighed it; its weight was 317 grains. In
seven days it lost 62 grains, or nearly one-fifth of its weight. It was
weighed again in August of the same year, but had not lost any more of
its weight; hence it had become perfectly dry in the short space of seven
days. He also found that the sap-wood of oak lost more weight in drying
than the heart-wood, in the proportion of 10 to 7.
The time that is required to season or dry a piece of timber obviously
depends upon its magnitude; as a _general rule_, large timbers will not
continue good so long as small ones, as sufficient time is rarely given
for a thorough seasoning. The time required to dry a piece of timber, all
other things being alike, will depend on the quantity of surface exposed
to the action of the air; therefore, while the quantity of timber
remains the same, the larger the surface, the sooner it will dry. Also,
if the quantity of surface remains the same, the time of drying will be
proportioned to the quantity of matter; as the greater the quantity of
matter under the same surface, the longer it will be in drying.
As drying proceeds most rapidly in small pieces, it is therefore
important to reduce the timber to its proper scantlings or size for
use; for however dry a piece of timber may be, when it is cut to a
smaller scantling it will shrink and lose weight, being always less dry
in the centre than at the surface; and the more rapidly the drying has
been carried on, the greater will be the difference. Nevertheless, in
the first stage of seasoning it is best that it should proceed slowly;
otherwise, the external pores shrink so close as not to permit the
full evaporation of the internal moisture, and the piece would split
from unequal shrinking; and lastly, it should be reduced to the proper
scantling, as already observed, some time before it is to be framed.
Various tables have been given by writers on timber, the result of
algebraical calculations, of the times of seasoning and drying for
different woods of different lengths, breadths, and thicknesses, in the
open air; but as wood even of the same description and quality varies
so much, this matter is best left to those who are well acquainted with
timber. It may, however, be stated that the time required for drying
under cover is shorter than in the open air, in the proportion of 5 to 7.
The English shipwright considers that three years are required to
thoroughly season timber. The timbers for ships are usually cut out
to their shape and dimensions for about a year before they are framed
together, and they are commonly left a year longer in the skeleton shape
to complete the seasoning, as in that condition they are more favourably
situate as regards exposure to the air than when they are closely covered
in with planking.
It is worthy of mention that all the harder woods require increased care
in the seasoning, which is often badly begun by exposure to the sun or
hot winds in their native climates: their greater impenetrability to
the air the more disposes them to crack, and their comparative scarcity
and expense are also powerful arguments on the score of precaution. Oak
timber requires to be very carefully seasoned, as it is generally used
in buildings for the best description of work, and should unseasoned oak
be used for “panelling,” any shrinkage will be fatal to the work. Mr.
George Marshall, timber merchant (see the _Builder_, January 20, 1872),
with respect to seasoning oak timber, observes: “I should select oak
trees known to be old and hearty, with clean, straight butts, from 15
inches to 20 inches in diameter. I should then have the bark taken off
as they stand, and leave them thus till the winter; the sap will then
partially dry out, and make the wood a rich brown colour. As soon as they
are cut down, have them sawn up at once into the lengths you require the
panelling, 6 inches or 8 inches wide and 1 inch to 1½ inch thick. Be
careful to cut all the heart shakes, by having one cut through the centre
of the log before edging the boards to the required width. With regard
to the drying process, stack the boards in a shed with a good draught
through it, and load them down, with slips between each board, to prevent
warping. If this be done they will be found to dry well and speedily, and
they will not require to be exposed to the weather.”
Sir. Robert Phillips, on seasoning oak for panelling, states: “If the
tree is large enough for the purpose, cut it into four, in sections, by
drawing a vertical and horizontal line across the end, meeting in the
centre. If too small for this, cut it into 4½ inch or 6-inch plank, as
soon as possible after felling, and then stack _on end_ out in the open:
do not lay on the ground, but stand it as nearly _vertical_ on its end as
possible, and keep it wet during the first three months. If the weather
is dry, well _wet_ it with water poured on the top, and allowed to run
down. Let the ends stand on a piece of quartering, to keep it out of the
dirt, or it will be stained some distance up. After standing thus for
some six months, after putting it in a dry place for some time, cut it
into the scantlings you require, always bearing in mind that oak will,
after this seasoning, shrink at least half an inch to a foot, in width
and thickness. They should then be stacked and stripped, and covered with
spare boards, and weighted on the top, for at least six months--as much
more as possible--in a covered shed, with plenty of air, occasionally
turned over and shifted, till they are dry enough to make dust when
planed, and not turn the shaving black. They will then be fit for use.
“I should advise for the panels to be cut _feather-edged_ boards, in
radial lines from the centre of the tree: it will be a waste of material,
but will repay in the beauty of the wood, and the way it will stand
without warping. Most of the panels of our old cathedrals were rent (_not
sawn_) in this way, and stand admirably. The butt of the tree should be
taken, the top being used for a rougher purpose.”
Mr. George Marshall and Mr. Robert Phillips might have mentioned that
the oak trees should be of the _Quercus Robur_ species, and _not_ the
_Quercus Sessiliflora_. They are easily distinguished when growing by the
following peculiarities: The acorn-stalks of the _Robur_ are _long_; the
acorns grow singly, or seldom two on the same footstalk; the leaves are
_short_. The acorn-stalks of the _Sessiliflora_ are _short_; the acorns
grow in clusters of two or three, close to the stem of the branch; the
leaves are _long_.
WATER SEASONING.
When there is not time for gradual drying, the best method, perhaps,
that can be adopted, especially for sappy timber, and if strength is not
principally required, is immediately on felling to immerse it in running
water; and after allowing it to remain there about a fortnight, to set
it in the wind to dry. Some persons prefer this method of seasoning
timber, as they say it prevents cleaving, and strips and seasons better
afterwards. This process has been adopted with good results by placing
the boards end on at the head of a mill race for fourteen or twenty days,
at most, and then setting the boards upright, and subject to the action
of the sun and wind; though it is questionable whether the sun will not
do them more harm than good. As they stand, turn them daily, and when
perfectly dry--which process will take about one month--it is considered
they will be found to floor better than timber after many years of dry
seasoning. The sap-wood of oak is said to be improved by this method,
being much less subject to be worm-eaten; and providing it is placed in
fresh running water, Mr. G. A. Rogers, the celebrated wood carver, is of
opinion that the colour of the oak is improved. The more tender woods,
such as alder and the like, are less subject to the worm when water
seasoned. Beech is said to be much benefited by immersion. It should be
remembered that the timber should be altogether under water (chained
down beneath its surface), as partial immersion is very destructive. Du
Hamel considers “that where strength is required, wood ought not to be
put in water.” Timber should never be kept floating in ponds or docks,
as in London; but it should be stacked, as at Liverpool and Gloucester.
Timber that has been lying for months in ponds or docks is sometimes cut
up, and in six or seven days fixed in a building; consequently, the usual
result takes place, viz. dry rot. After having been swelled by soaking
much beyond its former bulk, the baulk of timber is put on the saw-pit,
and cut into scantlings, and framed while in this wet state, therefore
it cannot be surprising that the dry rot soon appears as a natural
consequence.
Amongst wheelwrights the water seasoning is in general favour. It is
said that the colour of the white woods is improved by water seasoning,
boiling, or steaming. The Venetians place the oak used for gun-carriages
in water for two years before it is used, and the timber for sea service
two or three years under water. The Turks do not appear to pay any
attention to seasoning, for they fell their timber at all times of the
year without any regard to the season, and although they grow very good
oak, it is used so green and unseasoned that it not only twists, but
decays rapidly, as anyone may observe in the houses at Constantinople and
other Turkish towns.
Timber is rendered more durable by placing it in a stream of water,
saturated with lime, for eight or ten days, and it also makes it less
liable to the attack of worms; but it, however, becomes hard after being
dried, and is difficult to be worked; and therefore the process should
be applied to timber which has been sawn into scantlings, and is ready
for use. Mr. William Chapman, in 1812, considered that an immersion of
timber in hot limewash in deep ponds, exposing little surface to the air,
merited a trial; but in 1816, from experiments he had made, he was of
opinion that it had proved injurious to timber.
Evelyn states that green elm, if plunged for a few days in water
(especially salt water), obtains an admirable seasoning. According to
Society of Arts _Trans._, 1819, every trace of fungus was eradicated from
the ship “Eden,” by its remaining eighteen months under sea water. Salt
water is considered good for ship timber, but for timber to be employed
in the construction of dwelling-houses, fresh water is better. Pliny
notices, as a fact, that certain woods on being dried after immersion in
the sea acquire additional density and durability. M. de Lapparent, late
Director of the French Navy, considers that timber cannot be seasoned
in salt water, but in fresh, or at the most, in brackish water. The
condition of the timber which, at the port of Rochefort, is kept in
ditches filled with fresh water is in this respect most favourable; that
kept at Toulon, Brest, and Lorient, where the water is brackish, is much
less so; but to estimate their relative advantages, it would be necessary
to test the average density of these waters. It is, however, at Cherbourg
that this natural preparation of timber is the most inefficient, as the
beds-of sand in which the timber is buried, near the Pool of Tourlaville,
contain but a small quantity of water, which, being nearly always
stagnant, very quickly exhausts itself, and is very prejudicial.
At the Cologne International Agricultural Exhibition, in 1865, three
sleepers were exhibited from the Magdeburg Leipsiger Railway, from the
Salt Work Branch, at Stassfurt, laid in 1857. These were moistened by the
refuse of the salt which was lost from the load and by the rain. The jury
in their Report stated that these sleepers proved nothing, “because every
old table on which fish or meat has been salted, proves that a constant
moistening with salt water preserves the wood from decay, but as soon
as the process of salting is given up, the salted matter is immediately
given out, and the timber soon decays. In this case it would have been
important to have known that these sleepers, after having been salted,
had lain anywhere else than in the Salt Work Branch without getting fresh
salt applied, and then to have seen if they would have been as perfect as
they are now. They, indeed, prove nothing but the fact that if sleepers
be daily sprinkled with salt they will remain sound, but the price paid
for this durability might be very considerable.” As the use of salt as
a preservative agent will be considered in the next chapter, it will be
best to defer the consideration of salt-water seasoning until then.
In India, teak, sál, and blackwood, &c., improve by lying in water, or
in the soft black mud of an estuary: there is one exception, viz. heddé,
which deteriorates from steeping, and should be carted to its destination.
Evelyn states that he had found a fortnight’s immersion in river water
sufficient, and this opinion is held by Silloway, a North American
authority; but Dr. Porcher, a South American writer, recommends a six
months’ immersion in water, and a six months’ exposure to wind and shade.
Vitruvius and Alberti consider that timber should be left immersed in a
running stream thirty days.
It is considered that the longer wood has remained under water, the more
rapidly it dries; for instance, every one is aware that the firewood
brought out of the river is less green and burns better than that brought
by waggon or boat.
In 1817, Admiral Count Chateauvieux, a Sardinian naval officer, observed
to Mr. McWilliam that it was a custom at the Royal Arsenal, at Genoa,
as a preventive against the diseases of timber, to steep it about three
years in fresh water immediately after it is felled. Mr. James Dickson,
of Gottenburg, timber merchant (member of the firm Peter Dickson and
Company, London), many years engaged in the Swedish timber trade,
observed in 1835, “If square timber lies in the water two or three years,
it rends at the heart, but I should not say it would, perhaps, for the
first year; but the exterior part rends soon by exposure to the weather.”
In 1818, the Chevalier de Campugano, Secretary of Legation to the Spanish
Embassy, stated that in Spain, when timber is felled, it is generally
laid in water for a considerable time.
The sap in timber, by reason of the matters which it holds in solution,
is denser than pure water; moreover, it is enclosed in fibres or channels
permeable at the ends.
Supposing in submerged timber, the surrounding water to be flowing, or at
least changing, this water will conclude by occupying, if not altogether,
at least in a great degree, the place of the sap, which will have issued
forth, carrying with it the fermenting principle with which it is
charged. The timber, therefore, which has remained _sufficiently long_
in the water ought to be much less susceptible of fermentation than that
seasoned only by the atmosphere. Besides, as pure water evaporates much
easier than that which contains certain principles, this timber ought to
be seasoned much sooner than the other.
Of steeping generally, whether in cold or warm water, it must be
particularly observed that it dissolves the substance of the wood, and
necessarily renders it lighter; indeed, it is known that notwithstanding
wood that is carefully submerged remains good for a very long period
after the water has dissolved a certain soluble part, it is, when taken
out and dried, liable to be brittle, and unfit for any other work but
joinery.
SEASONING BY STEAMING AND BOILING, ETC.
For the purposes of joinery, steaming and boiling are very good methods,
as the loss of elasticity and strength which they produce, and which
are essential in carpentry, is compensated by the tendency to shrinkage
being reduced; the durability also is said by some to be rather improved
than otherwise, at least from steaming. If steaming be not carried on
too quickly it will answer, but if it be pushed with too much vigour
it is very apt to produce a permanent warping and distortion of the
material. Oak of British growth may be seasoned by this process, as
without this precaution it requires a long time to season. It has been
ascertained, that of woods seasoned by these methods, those dried soonest
that had been steamed; but the drying in either case should be somewhat
gradual, and four hours are generally sufficient for the boiling or
steaming process. The question of time will depend upon circumstances:
some persons consider that one hour should be allowed for every inch
in thickness. In some dockyards, salt water is used in the boilers, in
others fresh, from considerations of convenience; and the fact is, plank
boiled in salt water never gets rid of the salts that naturally enter the
pores of the wood in boiling; and such being the case, the ship in which
this plank is used is much more liable to the effects of damp than she
would have been if the plank had been boiled in fresh water.
Boiling and steaming are likewise employed for softening woods, to
facilitate the cutting as well as bending of them. Thus, in Taylor’s
patent machines for making casks, the blocks intended for the staves are
cut out of white Canada oak to the size of 30 inches by 5 inches and
smaller. They are well steamed, and then sliced into pieces ½ inch or
⅝ inch thick, at the rate of 200 in each minute, by a process far more
rapid and economical than sawing; the instrument being a revolving iron
plate of 12 feet diameter, with two radial knives arranged somewhat like
the irons of an ordinary plane or spokeshave.
How far steaming or boiling affects the durability of timber has not been
satisfactorily ascertained; but it is said that the planks of a ship
near the bows, which are bent by steaming, have never been observed to
be affected with dry rot. With respect to boiling, Du Hamel’s opinion is
not favourable as to its adding to the durability of timber; for when a
piece of dry wood was immersed in boiling water, and afterwards dried in
a stove, it not only lost the water it had imbibed, but also a part of
its substance; and when the experiment was repeated with the same piece
of wood, it lost more of its substance the second time than it did the
first. Tredgold--no mean authority--considers that “boiled or steamed
timber shrinks less, and stands better than that which is naturally
seasoned.” Barlow is of opinion that “the seasoning goes on more rapidly
after the piece is steamed than when boiled.”
At the close of the Crimean and Baltic campaigns the port of Cherbourg
was almost completely cleared of staves sufficiently seasoned for making
casks. The engineer at the head of the coopering department determined to
boil in fresh water the newly-cut staves, and compare the time of their
seasoning with that of other staves cut from the same forests, but not
prepared; and the result was that after four or five months’ exposure
to the atmosphere, the boiled staves were perfectly fit for working up,
while to bring the others to the same point fifteen months were barely
sufficient.
Steaming is understood to prevent dry rot. No doubt boiling and steaming
partly remove the ferment spores, but _may not_ destroy the vitality
of those remaining. For, according to Milne-Edwards, on ‘Spontaneous
Generation.’ he has seen tardigrades resist the prolonged action of a
temperature of 248° Fahr., and has known them to survive a temperature of
284° Fahr. That low forms of vegetation are fully as tenacious of life
cannot be doubted.
Boiling and steaming also coagulate the albumen at 140° Fahr. Although
coagulated albumen is insoluble in water, the water solution is by this
heating process sealed up in the wood, and the cohesion of the latter is
said to be diminished.
The first essays in the art of drying wood artificially carry us back to
a period now tolerably remote. Wollaston and Fourcroy both recommended
the drying of wood in ovens. Newmann, a German chemist, suggested another
method, which has since been adopted in a somewhat different form, i.
e. _steaming_ the wood. Newmann placed the wood to be dried in a large
wooden chest, taking care to leave spaces between the pieces, and then
turned on the steam from a boiler provided for the purpose. The condensed
steam, charged with albuminous matter taken up from the wood, or rather
from its surface, was run off from time to time, and the process of the
operation was judged by the colour of the water. When the latter was
clear and colourless the chest was opened, and the wood withdrawn for use
without further preparation. The process would have been useful enough
if _superheated_ steam, which would have dried the wood by absorbing
the moisture, could have been used, but the cost of the process would
doubtless have been too high to permit of its practical application.
In 1837, M. de Mecquenem devised a method of desiccation, in which the
pieces of wood to be dried were placed in a closed chamber, and subjected
to a current of hot air, heated for the purpose by a special apparatus,
and driven by a blower. The air entered by apertures in the lower part
of the chambers, and escaped at the top laden with the moisture absorbed
from the wood.
In 1839, M. Charpentier obtained a _brévet d’invention_ for a process of
drying wood in hermetically-closed chambers. The wood was subjected to
the action of air heated by contact with metal plates covering the flue
of a coke furnace. This air entered by conduits on the level of the floor
of the chamber, and escaped at the top through apertures leading into the
chimney of the furnace.
In the same year, M. Saint Preuve invented a process for forcing steam
into pores of the wood, and, by condensation of this steam in the pores,
sucking in a preservative preparation.
In 1847, MM. Brochard and Watteau’s process was introduced. It consists
simply of filling the cylinder with steam, and making a vacuum by forcing
in a cold solution of salt, &c.
The plan which has been for some years in use in England is the
injection, by means of a ventilator, of hot air into the drying stove
where the wood is placed: by this the temperature is gently and gradually
raised until it reaches boiling heat. But, as wood is one of the worst
conductors known of caloric, if this plan is applied to large logs, the
interior fibres still retain their original bulk, while those near the
surface have a tendency to shrink; the consequence of which would be
cracks and splits of more or less depth.
Timber may be dried by passing rapid currents of heated air through it
under pressure. This plan was carried out with the timber used for the
floorings of the Coal Exchange, London. The wood was taken in its natural
state, and in less than ten days it was thoroughly seasoned. In some
cases, from 10 to 48 per cent. of moisture was taken out of the wood,
and although the floorings have now been down a great many years, it is
stated that very little shrinkage has been found, except in the case of
a few pieces which were put down in the latter portion of the work, and
which had not been submitted to the seasoning process.
The process of desiccation, patented by Messrs. Davison and Symington,
in 1844, is of great practical value in reducing the time requisite
for seasoning timber. It is peculiarly applicable to the seasoning of
flooring boards and of the wood used in joiners’ work. Care must be
exercised when removing the timber from the stove to the building in
which it is to be used, that it be not exposed to the wet, nor even to a
damp atmosphere for any lengthened period. The advantage of this process
over the ordinary stoving consists in the temperature never being so
high as to scorch the wood, by which the strength of the fibres would
be injured; and in the facility for removing the vapour as fast as it
is expelled from the wood, in consequence of the air being propelled
through the stove at any required velocity and temperature. As compared
with furnace and steam-stoving ordinarily employed to desiccate woods,
the great superiority of this process is established by its seasoning
the wood quite as rapidly, but much more thoroughly; and instead of wood
being rendered brittle, as it is to some extent by stoving, this mode
does not reduce the strength and tenacity of the wood. The principle
of the invention is propelled currents of heated air; but the heat
has to be regulated according to the texture of the various woods.
Honduras mahogany might be exposed to a heat of 300°, and the whole of
the moisture can be taken out in three days. Timber 9 inches square is
considered by Mr. Davison a proper size for his invention. This process
is described as “A method or methods of drying, seasoning, and hardening
wood, and other articles, parts of which are also applicable to the
desiccation of vegetable substances generally.” The first or principal
part of the invention consists in drying, seasoning, and hardening wood
and other articles--among which other articles are included generally all
things made of wood, or chiefly of wood--by means, as has been stated,
of rapid currents of heated air. The manner in which these currents of
heated air are produced, is by an apparatus consisting of a furnace
and a series of pipes withinside of a core of brickwork. On each side
of the furnace, on a level with the fire-bars, is a horizontal tube;
communicating and springing from these tubes are a series of eighteen
tubes placed vertically and parallel to each other over the furnace. The
outer end of one of the horizontal tubes communicates with a fan or other
impelling apparatus for driving a constant stream of atmospheric air
through the tubes. As the air passes through the tubes it becomes heated
at a high temperature, and rushes out at the farther end of the other
horizontal tube, and is thus conveyed to the place where it is applied.
The materials to be subjected to the heated currents, such as logs,
deals, &c., by outward application, must be placed in closed chambers,
galleries, vaults, or flues, which are to be of any suitable form or
magnitude; but it is recommended that they should be made of fire-brick,
and have double doors or shutters for introducing or removing the wood.
Honourable Mention was made of Messrs. Davison and Symington’s process of
desiccation, by the jury, Class IV., Exhibition of 1851, England.
Some amusing instances are related of the efficiency of Davison and
Symington’s process. Thus, a violin had been in the owner’s possession
for upwards of sixteen years; how old it was when he first had it is
not known. Upon being exposed to this process it lost, in eight hours,
no less than five-sixths (nearly five and two-thirds) per cent. of its
own weight. This there is every reason to believe was owing to the
blocks glued inside, for the purpose of holding the more slender parts
together. A violin maker of high reputation, having an order to make
an instrument for one of the first violinists of the day, was requested
to have the wood seasoned by this process; only three days were allowed
for the experiment, in which the wood was seasoned and sent home. The
two heaviest pieces were reduced in weight 2½ lbs. It is ascertained
that, by this means of drying, the effect of age has been given to the
instrument made from the above wood, and it was, in 1848, _first fiddle_
in the orchestra of Her Majesty’s Theatre, London. The wood had been
in the possession of its owners for eight years, and it was sent from
Switzerland, in the first instance, as _dry wood_.
In proof of the value of this invention for the manufacture and cleansing
of brewers’ casks, it was stated, in 1848, that since its adoption at
Trueman’s brewery, Spitalfields, a saving of 300 tons of coals has been
effected annually.
Flues or chambers for the heated air may be constructed in parallel
lines, either in the floors or upright walls of a building, having narrow
openings through which the heated air may issue in thin streams, and
spread itself over the surface of the wood. If the openings are in the
floor, the wood will require to be placed in an upright position; but if
admitted in a horizontal direction, standards and skeleton shelves will
be necessary to lay it upon. The great object, in all cases, is to bring
the heated air as speedily as possible into contact with the wood, and to
allow it, after it has done its office, to pass away as speedily.
Furnaces and apparatus for the production of rapid currents of heated
air may be erected to prepare any quantity of timber or articles of wood
at one time, but care should be taken that whatever the size of the
outlet may be from the series of pipes or vessels by which the heat is
generated, an outlet of at least equal dimensions is left for the free
exit of the air and the vapours thrown off. It should also be observed,
in constructing the open space in the floor or upright walls for the
stream of heated air to pass towards the timber, that the superficial
area of the whole of them combined does not exceed the dimensions of the
principal outlet of the pipes at the extremity of the furnace, so that a
free current of heated air may be allowed to pass uniformly throughout
the chambers containing the wood to be prepared. The temperature proper
to be given to the air, and velocity to the current in each case, will
depend on the size, density, and maturity of the wood to be acted upon.
The inventors found by their experiments that wood generally may be
advantageously subjected to currents of air raised to a temperature of
400° Fahr., when the currents are impelled at the rate of 100 feet per
second. But when the wood is in a green state, it is better to commence
at a lower temperature, say from 150° to 200°, and gradually raise it to
the high degree before stated, as the desiccation proceeds, an object
which may, in some cases, be facilitated by carrying a cold-air drain
from the fanner or other propelling apparatus, and attaching a damper to
it, so that any quantity of cold air required to reduce the temperature
of the hot current may, from time to time, be admitted. When, again, the
wood is in the log or unconverted state, it should be bored or augured
out in the centre, and the current of hot air caused to traverse it as
well interiorly as exteriorly, whereby much time will be saved in the
process of desiccation, and a more uniform result obtained.
Woods treated in this manner, and with the above modifications when
requisite, part rapidly with their natural sap and any other aqueous
matter which they may contain, and the fibres are brought closer together.
With respect to the time required to season the wood upon this plan, much
must depend upon the original state of dryness it may be in, as well
as the quality and temperature of the heated air forced into contact
with it. It may suffice to remark that the wood may safely remain thus
exposed till any escape of moisture ceases to be perceptible. This may be
readily known, either by applying a mirror or any polished surface to the
outlet, or by calculating the quantity of moisture removed from the wood,
which will be found to range between ¼ and ⅟12th of its whole weight.
For the purpose of ascertaining more correctly the amount of moisture
removed from time to time, when the wood is placed in seasoning chambers
as already described, an opening should be constructed in the chamber,
in any convenient position, through which a specimen of the wood may be
withdrawn and weighed.
Between 1848 and 1853, Mr. Bethell, who had paid much attention to the
subject, obtained several patents, both in England and France, for stoves
for drying wood. In his English patent of 1848, and the subsequent French
one of 1853, we find a description of a peculiar kind of stove, on the
following plan:
It consisted of a rectangular chamber formed of three walls and vaulted
over, the whole in brickwork, with a certain thickness of slag in the
centre, to prevent loss of heat. One extremity of the chamber was open to
admit of the introduction of the wood by means of a truck running upon
longitudinal iron rails. The opening was closed with a double door when
the chamber was full. On the exterior of the opposite end of the chamber
was a furnace to burn coal, coke, wood, or tar, according as it was
desired to _dry_ the wood simply, or, in the words of the inventor, to
_smoke_ it, i. e., to impregnate it with the antiseptic gaseous matters
evolved in the imperfect combustion of certain tarry substances. The
heated air or smoke entered through a flue running along the floor and
branching at the end, and it escaped, or was pumped out, at the top of
the vaults. Bethell considered that the interior of the chamber should be
kept at a temperature of 110° Fahr., and that the duration of the process
should be regulated by the condition of the wood. His experiments showed
that this time varied from eight to twelve hours, the rapidity being
attained at the cost of a relatively large expenditure of fuel. In point
of fact, the draught was too great to permit of the utilization of the
full amount of heat contained in the gaseous matter, which escaped at a
temperature very little below that at which it entered. The heat produced
by the fuel was badly utilized, and it is open to question whether,
under any circumstances, large pieces of wood, such as sleepers, could
be dried in so short a time as eight or twelve hours. The drying could
only be effected by the use of a very high degree of temperature, tending
to split the wood and weaken its strength. This view was confirmed by
the results obtained in a long series of experiments made, in 1852-3,
by an English manufacturing company, known as the Desiccating Company. A
low temperature, and long continuance of the drying process, appear to
be the conditions essential to the success of artificial desiccation,
particularly with wood intended for cabinet-making, turning, joinery,
ornamental work, &c., in which it is desirable, as far as possible,
to prevent splitting, warping, and other changes of structure in
the material. These results, it would seem, were not secured by the
arrangements above described.
Some years since, a stove was constructed for Messrs. S. and J. Holme,
very extensive builders at Liverpool, for the purpose of drying timber
for floors, and other fittings of houses, &c., by the application of
Messrs. Price and Manby’s patent warming apparatus; the want of seasoned
timber, with the great number of men they employed, being a serious
inconvenience and loss. In their large undertakings Messrs. Holme found
a difficulty in keeping a stock of dry timber. The dimensions of the
stove in which the timber was to be dried was 43 feet long, 11 feet
wide, and 17 feet 6 inches high, and the cost of the apparatus was about
150_l_. It was calculated to hold about 30,000 superficial feet of 1-inch
boards, which, upon the steam-pipe system, occupied full three weeks
in drying. This apparatus of Messrs. Price and Manby, with rather less
fuel, was considered to thoroughly dry each stove-full in ten days, thus
saving a consumption of ten days’ fuel, independent of the advantages
of expediting business. The average temperature was 104°, and as the
continuous stream of pure air passing between the metallic plates was
divested of its moisture, it carried off the dampness of the timber in
an imperceptible manner. An experiment was tried, by having a flooring
batten, 7 inches by 1¼ inch, cut from a piece of timber which had been
floated, and was as full of water as it could be, placed in the stove;
and when the temperature was 102°, it remained there five days, and when
sawn down into ⅝ inch thick, and planed, it was found to be perfectly dry
throughout. The heat was so gentle, and the evaporation so equal, that
the timber was never rent, as when exposed to the air and a hot sun: in
short, Messrs. Holme considered it one of the most perfect timber stoves
that had been made.
It may be remarked with respect to desiccation, that the timber to be
artificially dried is generally exposed to a great heat for a short
time, rather than to a moderate heat for a lengthened one; and the air,
saturated with the vapour thus produced, is generally very imperfectly
removed. Wood so treated is almost sure to split, from the unequal
contraction to which it is exposed; and the pores are also very liable to
reopen on the wood being withdrawn from the stove, because there is no
gradual and permanent change in their mechanical structure. It is only
within the last few years past that the artificial desiccation of wood,
before its impregnation with an antiseptic preparation in closed vessels,
has been frequently adopted in practice.
We cannot give a better termination to the few remarks we have made about
“steaming and boiling timber,” than by quoting the opinion of the late
Sir Charles Barry, R.A., architect to the new Houses of Parliament, which
we propose doing in the following manner:
“YORK ROAD, LAMBETH, _Nov. 30, 1844_.
SIR,
In reply to your application, we beg to acquaint you that we
are willing to undertake the ordinary works required in the
finishings of the new Palace of Westminster. … The wainscot to
be used in the joiner’s work is assumed to be from the best
Crown Riga wainscot in the logs, and from pipe-staves of the
best quality, in equal proportions, to be _prepared for use by
steaming_, or otherwise.…
_Grissell & Peto._”
Charles Barry, Esq.
Sir Charles Barry recommended this tender to the Treasury for acceptance;
but we fancy that he was doubtful about the efficacy of steaming, as we
think will appear from the following extract from an “Agreement between
Sir Charles Barry and Messrs. Grissell and Peto, builders:
“_First._ That the wainscot is assumed to be from the log and pipe-staves
in equal quantities; the prime cost of which, in inch boards, _seasoned
by steam_, or other artificial means, so as to be fit for use, is
calculated at 6½_d._ per foot superficial.
“_Secondly._ That _if it should be found necessary to make use of
thoroughly dry wainscot boards_ for the whole or any portion of
the joiner’s work, seasoned by natural means (viz. exposure to the
atmosphere), the prime cost of such boards, with the addition of a
profit of 7½ per cent., is to be allowed for them, over and above the
price of 6½_d._ per foot superficial, the prime cost of wainscot boards
provided for in the contract, as above stated.” (Italics are our own.)
SEASONING BY SMOKE DRYING.
Smoke drying in an open chamber, or the burning of furze, fern, shavings,
or straw under the wood, is said to give it hardness and durability;
and, by rendering it bitter, destroys and prevents worms. It also
destroys the germ of any fungus which may have commenced. It is an old
and well-founded observation that smoke drying contributes much to the
hardness and durability of woods. Virgil appears to have been aware of
its utility, when he wrote the passage which is thus translated by Dryden:
“Of beech, the plough-tail, and the bending yoke,
Or softer linden, hardened in the smoke.”--GEORGICS, i., 225.
Beckman, in his ‘History of Inventions,’ quotes a passage from Hesiod to
the same effect; and adds, “as the houses of the ancients were so smoky,
it may be easily comprehended how, by means of smoke, they could dry and
harden pieces of timber.” In this manner were prepared the pieces of wood
destined for ploughs, waggons, and the rudders of vessels:
“These long suspend, where smoke their strength explores,
And seasons into use, and binds their pores.”--VIRGIL.
The late Brigadier-General Sir Samuel Bentham bestowed much time and
attention in endeavouring to ascertain the quickest and best means of
drying oak. In his letter to the Navy Board, 6th March, 1812, he says:
“By exposing block shells to the smoke of burning wood, they become in
the course of two or three days well seasoned in every respect, hard,
bright coloured, and, as it were, polished. But it was found in a very
short time that the acid with which the shells were thus impregnated very
rapidly corroded the iron pins which passed through them.
“In Russia many small articles, such as parts of wheels, wheel carriages,
and sledges, are prepared in this manner; so are wheels, at least in some
parts of America; and sabots and other small articles in France.”
In speaking of artificial heat, he says, in the same letter:
“From all the opportunities I have had of examining the state of timber
so prepared by artificial heat, the due seasoning without cracking has
appeared to depend on the ventilation happening to be _constant_, but
very _slow_, joined to such a due regulation of the heat as that the
_interior_ of the timber should dry, and keep pace in its contraction
with the outer circles.”
Mr. T. W. Silloway, in ‘American Carpentry,’ remarks: “If timber be dried
by heat, the outside will become hardened, and the pores closed, so that
moisture, instead of passing out, will be retained within.”
Bowden remarks, “that the timbers of a small ship underwent the process
of charring, either by suspending them over a fire of chips, or by
burning the exterior with red-hot irons, so as to char the external
surface. Air trunks were also formed between the timbers, for the
purpose of evaporating moisture. The state of this vessel was examined
five years after she was launched, and it appeared that, although the
timbers had been very strongly charred, fungi had grown to a considerable
extent on both sides abaft the fore channels, and that the plank near the
magazine was completely decayed.” _The power of vegetation broke through
the incrusted barrier against external affection._
A method is in operation at Tourlaville, near Cherbourg, for which the
inventor, M. Guibert, has taken out a patent, and it is said to give at
once more expeditious and sure results than those obtained from the use
of dry and hot air. It consists in filling the drying-stove with smoke,
produced by the distillation of certain combustible matters, such as
sawdust, waste tan, and smiths’ coals, &c. By means of a ventilator,
ingeniously arranged, a rotatory movement round the logs laid to season
is given to the smoke, so as to obtain an average uniform temperature in
every part. By this plan, as the distillation of combustibles is always
attended with a considerable discharge of steam, all cracks and splits
are said to be prevented.
There is much force in Sir Samuel Bentham’s observations respecting the
drying of timber by artificial heat: it is certainly not well to attempt
to dry it _too_ quickly, for if it be subjected to great heat, a large
portion of the carbon will pass off, and thereby weaken the timber.
Timber too suddenly dried cracks badly, and is thus materially injured:
planks of larch or beech are liable to warp and twist if their drying is
hastened.
STOVE DRYING.
In some of the large manufactories for cabinet work, the premises are
heated by steam pipes, in which case they have a close stove in every
workshop heated many degrees beyond the general temperature, for giving
the final seasoning to the wood; for heating the cauls; and for warming
the glue, which is then done by opening a small steam pipe into the outer
vessel of the glue-pot. The arrangement is extremely clean, safe from
fire, and the degree of heat is very much under control.
In some manufactories, the wood is placed for a few days before it is
worked up in a drying-room heated by means of stoves, steam or hot water,
to several degrees beyond the temperature to which the finished work
is likely to be subjected. Such rooms are frequently made as air-tight
as possible, which appears to be a mistake,[1] as the wood is then
surrounded by a warm but stagnant atmosphere, which retains whatever
moisture it may have evaporated from the wood.
Fire-stoves for drying the timber were placed in the magazine,
bread-room, and other parts of the ‘Royal Charlotte’ ship; and the evil
of this practice was soon shown, for the vessel became dry rotten in
_twelve months_.[2]
Wood sometimes undergoes a baking process for veneering. Fourcroy has
recommended baking timber in an oven, and he has asserted that it would
render timber more durable; “but,” says Boyden, “it should be subjected
to a very strong heat, lest in endeavouring to prevent vegetation,
we should give it birth.” Captain Shaw[3] observes: “Any artificial
heating which burns the air is most injurious to wood and all combustible
materials, and renders them much more inflammable than they would be if
only exposed to the temperature of the atmosphere.”
SEASONING BY SCORCHING AND CHARRING.
Scorching and charring are good for preventing and destroying infection
in timber, but have to be done slowly, and only to timber that is
already thoroughly seasoned; otherwise, by incrusting the surface,
the evaporation of any internal moisture is intercepted, and decay in
the heart soon ensues; if done hastily, cracks are also caused on the
surface, and which, receiving from the wood a moisture for which there is
not a sufficient means of evaporation, renders it soon liable to decay.
Charring has little or no control over internal corruption, though it is
a good preventive against external infection: it increases the durability
of dry, but promotes the decay of wet timber. Farmers very often resort
to this method for the preservation of their fence-posts; the charring
should extend a little above their contact with the ground. Unless they
discriminate between green and unseasoned timber, these operations will
prove injurious instead of beneficial.
We have already quoted Sir Charles Barry in favour of _steaming_ wood;
we now intend giving the opinion of a former pupil of his with regard to
_charring_ it. Mr. George Vulliamy, architect to the Metropolitan Board
of Works, in a specification for oak fencing which was fixed round the
boundaries of Finsbury Park, London, in 1867, writes as follows:--“Dig
out the ground for the upright standards where shall be directed, and
fill in and ram round same with dry burnt earth, stones, and rubbish (the
burnt clay will be provided); enclose the boundaries of Park, as shall be
directed, with _dry and well-seasoned_ heart of English oak, _wrought_
upright standards, 6 inches by 5 inches, and 8 feet 6 inches total
length, with cut and _splayed_ tops, holes drilled for oak pins, and
mortised for horizontal rails, as shown on detailed drawings; to stand 5
feet 3 inches out of ground, and _the ends in ground to be well charred
before fixing_.” (The italics are our own.)
Our ancestors used charcoal and charred wood, on account of their
durability, for landmarks in the ground between estates. The
incorruptibility of charcoal is well known. Amongst other advantages,
rats will not touch it; neither will the white ants nor cockroaches, so
common in the Indies, commit their depredations where charring has been
employed.
The ‘Revue Horticole’ states that it has been proved by recent
experiments, that the best mode of prolonging the duration of wood is to
char it, and then paint it over with three or four coats of pitch. Many
of the sleepers now laid down on the Belgian railways are charred, the
engineers preferring this process to any other.
The superficial carbonization, or charring of wood, as a preservative
means, has long been practised. The Venetians have used charring for
timber for a long period, particularly for piles. In France, M. de
Lapparent recently proposed to apply it to the timber used in the French
Navy. Some experiments, which were undertaken with a view to determine
its practicability, terminated satisfactorily; and the Minister of Marine
ordered the process to be introduced into the Imperial dockyards.
M. de Lapparent makes use of a gas blowpipe, the flame from which is
allowed to play upon every part of the piece of timber in succession.
By this means the degree of torrefaction may be regulated at will. The
method is applicable to woodwork of all kinds; and the charring, it is
said, does not destroy the sharpness of any mouldings with which the wood
may be ornamented.
In the ‘Journal des Savants,’ Feb. 15, 1666, appears the following: “The
Portugals scorch their ships, insomuch that in the quick works there is a
coaly crust of about an inch thick; but this is dangerous, it happening,
not seldom, that the whole vessel is burnt.” It is no wonder that the
Portuguese ships should frequently fire in the operation, as their plank
was charred an inch deep. A mere charring, if done properly, after the
timbers had been thoroughly seasoned by air, would have been sufficient.
Charring seasoned wood is known to be a most effectual mode of
preservation against rot in timber: thus do piles, when charred, last for
ages in water or moist soil. Charred wood has been dug up, which must
have lain in the ground for 1500 years, and was then found perfectly
sound. After the Temple of Diana, at Ephesus, was destroyed, it was
found to have been built on charred piles; and at Herculaneum, after 2000
years, the charred wood was found to be whole and undiminished. But we
find Sir Christopher Wren did not approve of charred piles, except in a
soil where they would be constantly wet. So, in order to attain a firmer
foundation for St. Paul’s Cathedral, he had the ground excavated to an
immense depth before a stone of the building was laid.
From time immemorial it has been the practice, particularly in France,
to burn the ends of the poles driven into the ground to preserve them
from decay. According to the remark of the celebrated Carlomb, we should
always take into serious consideration old and well-known customs; but in
this instance it is easy to admit the preserving effect of carbonization.
Mr. James Randall,[4] Architect, states that he “oxidated several
pieces of wood with nitric acid, and with fire,” and these processes
were attended with success. Nearly the last sentence in his work is,
“_oxidation only_ can be relied on, in all cases, as an effectual cure.”
In charring, the surface of the timber is subjected to a considerable
heat, the primary effect of which is to exhaust the sap of the epidermis,
and to dry up the fermenting principles. Here this is done by long
exposure to the air; and, in the second place, below the outside layer
completely carbonized, a scorched surface is found, that is to say,
partly distilled and impregnated with the products of that distillation,
which is creosoted; the antiseptic properties of which are well known.
When Mr. Binmer was examined before the Commissioners of Woods, Forests,
&c., in 1792, he stated “that all steamed plank should be afterwards
dried and _burnt_ to extract the moisture.”
To a spontaneous carbonization must be attributed also the
unchangeableness of that timber entirely black, which is met with
everywhere in digging up the ground, where it has laid buried for ages.
In the neighbourhood of St. Malo, France, these specimens are very
common, and there most of the espaliers and vine props are made of wood,
black as ebony, and famous for its durability. They have been cut from
the trees of an old forest, submerged in the eighth century by an inroad
of the sea, which formerly crossed a Roman road, leading from Brittany to
Cotentin.
Not long after the beginning of the eighteenth century, the method of
heating or charring timber, before it was worked up, and also that of
stoving--that is, of heating in kilns with sand--were practised in
the Royal dockyards. The ‘Royal William,’ one of the most remarkable
instances of durability that the British Navy has supplied, was built
either wholly or in part of timber that had been charred. It was launched
in 1719; never repaired until 1757; and then, when surveyed afloat, in
1785, it appeared that the thick stuff and plank had been _burnt_ instead
of being _kilned_; and that the ends of the beams, the faying parts of
the breast-hooks, crutches, resters, knees, &c., had been gouged in a
manner then practised, which was called _snail-creeping_; by means of
which the air was conveyed to the different parts of the ship.[5]
The reason this method has not been persevered in, but nearly abandoned,
is owing to many causes: the difficulty and danger of the means adopted
for charring, when either straw, fern, or shavings are made use of; the
serious objection of burning the timber too deeply; or the encumbrance
of the apparatus, and the length of time occupied, if sand-kilns
sufficiently heated are used; and, finally, to indifference, or that
system of routine, against which the wisest plans often contend in vain.
In house-building, the charring process should be applied to the beams
and joists embedded in the walls, or surrounded with plaster; to the
joists of stables, washhouses, &c., which, although exposed to the free
air, are constantly surrounded by a warm and moist atmosphere, an active
cause of fermentation; to the wainscotting of ground floors; to the
flooring beneath parquet work; to the joints of tongues and rabbets;
for carbonization by means of gas still leaves to the wood, for working
purposes, all the sharpness of its edges. Charring is particularly useful
in the junction of all broad surfaces, and more essentially in those
which are cut either transverse or oblique to the grain of the wood,
as the sap vessels are then exposed to the absorption of moisture. The
butts of timbers are peculiarly liable to rot, because of affording a
lodgment for moisture without a free passage for air. No seasoned timber
should have its tubular parts exposed, nor should any timber have the saw
marks upon it, because the torn filaments absorb and retain moisture.
Allusion has already been made to the process adopted, near Cherbourg,
for preventing the decay of timber by means of gas.
By carbonization, a practical and economical means is afforded to railway
companies of preserving, almost for ever, the sleepers, and particularly
oak, which cannot be impregnated easily by the injection of mineral
salts. Let us suppose, for instance, that after, say ten or fifteen
years, the sleepers on a line are taken up for the length of a mile,
and replaced by new ones; the old, when rasped and burnt again, will
serve for the replacing the following mile, and so on, one mile after
the other. It might be equally serviceable to apply the same process to
injected beech, for the reason that it is almost impossible to make the
preserving liquid penetrate thoroughly the mass of the timber.
SEASONING BY EXTRACTION OF SAP.
Mr. John Stephen Langton’s method of seasoning by extraction of the
sap was patented in 1825, but is now almost wholly discontinued. It
consists in letting the timber into vertical iron cylinders, standing in
a cistern of water, closing the cylinders at top; and the water being
heated, and steam used to produce a partial vacuum, the sap relieved
from the atmospheric pressure oozes from the wood, and being converted
into vapour, passes off through a pipe provided for the purpose. The
time required is about ten weeks, and the cost is about ten shillings
per load; but the sap is wholly extracted, and the timber is said to
be fit and ready for any purpose; the diminution of weight is, with a
little more shrinkage, similar to that in seasoning by the common natural
process.[6]
Mr. Barlow’s patent provided for exhausting the air from one end of
the log while one or more atmospheres press upon the other end. This
artificial aerial circulation through the wood is prolonged at pleasure.
However excellent in theory, this process is not practicable.
In October, 1844, M. Tissier proposed to place wood in a close vessel,
and subject it to a current of hot dry air; and in 1847, Mr. Miller
proposed to inject hot air through beams of wood to drive out the sap.
In 1851, M. Meyer d’Uslaw proposed to first dilate the pores of the wood
with steam, and then place it in a hermetically closed chamber, and make
a vacuum there.
The following system of preparing timber for the Navy was, not many years
since, adopted in South Russia. A full account of the practice will be
found in Oliphant’s ‘Russian Shores of the Black Sea,’ 1853. The only
name we can give it is
“‘SEASONING’ BY BRIBES.”
A certain quantity of well-seasoned oak being required, Government issues
tenders for the supply of the requisite amount. A number of contractors
submit their tenders to a board appointed for the purpose of receiving
them, who are regulated in the choice of a contractor not by the amount
of his tender, but of his bribe. The _fortunate_ individual selected
immediately sub-contracts upon a somewhat similar principle. Arranging
to be supplied with the timber for half the amount of his tender, the
sub-contractor carries on the game, and perhaps the eighth link in this
contracting chain is the man who, for an absurdly low figure, undertakes
to produce the _seasoned_ wood.
His agents in the central provinces accordingly float a quantity of
green pines and firs down the Dnieper and Bog to Nicholaeff, which are
duly handed up to the head contractor, each man pocketing the difference
between his contract and that of his neighbour. When the wood is produced
before the board appointed to inspect it, another bribe _seasons_ it; and
the Government, after paying the price of well-seasoned oak, is surprised
that the 120-gun ship, which it has been built of it, is unfit for
service in five years.
“Mark but my fall, and that that ruin’d me,
Corruption.”--SHAKSPEARE.
A few words can only be given to a most important matter, viz., the
_second seasoning_, which many woods require. If floor-boards are only
laid down at first on the joists of a building, and at the expiration of
one year wedged tight and nailed down, those unsightly openings caused
by shrinkage, which form a harbour for dirt and vermin, will be avoided,
as the wood will have had an opportunity of shrinking. Doors, sashes,
architraves in long lengths, will also be better if made up some time
before they are required for use. Many Indian woods require a second
seasoning--kara mardá, for instance, a favourite wood with Indian railway
engineers. Even sál and teak are not exempt. Teak shrinks sideways least
of all woods. In the ‘Tortoise,’ store ship, when fifty years old, no
openings were found to exist between the boards; yet Colonel Lloyd says
he found the teak timbers used by him in constructing a large room in
the Mauritius to have shrunk ¾ of an inch in 38 feet. Thus a space of ⅜
of an inch must have been left at each end of the beam, where moisture
could lodge and fungi exist, obtaining their nourishment from the wood.
If unseasoned teak is used for ships, dry rot will in time find a place.
It may be said that teak is a very hard wood, and very durable; yet “the
mills of the gods,” says an ancient philosopher, “grind slow, very slow,
but they grind to powder;” _and so do the fungi mills_.
CHAPTER V.
ON SEASONING TIMBER BY PATENT PROCESSES, ETC.
Long years of practical experience has shown that timber, however prone
to dry or wet rot, may be preserved from both by the use of certain
metallic solutions, or other suitable protective matters.
All the various processes may be said somewhat to reduce the transverse
strength of the timber when dry, and the metallic salts are affected
at the iron bolts or fastenings. The natural juices of some woods do
this; and bolts which have united beams of elm and pitch pine will often
corrode entirely away at the junction.
The processes adopted for resisting the chemical changes in the tissues
of the wood are all founded on the principle that it is essential to
inject some material which shall at once precipitate the coaguable
portion of the albumen retained in the tissues of the wood in a
permanent insoluble form, so that it will not hereafter be susceptible
of putrefactive decomposition. For this purpose, many substances, many
solutions, have been employed with variable success, but materials have
been sometimes introduced for this purpose which produced an effect just
the opposite to what was anticipated.
Experience has shown that timber is permeable, at least by aqueous
solutions, only so long as the sap channels are free from incrustation.
Such in general is the case with beech, elm, poplar, and hornbeam, the
capillary tubes of which are always open, or, at least, close very
slowly. At the same time it may be said that there must remain ever in
these species some parts impervious to injection, whilst it is almost
impossible but that a certain portion of the fibres will be more or less
incrusted. The sap woods, on the other hand, of every species appear
quite pervious.
Very little is known of any preservative process adopted in ancient
times. Pliny observes that the ancients used garlic boiled in vinegar
with considerable success, especially with reference to preserving timber
from worms: he also states that the oil of cedar will protect any timber
anointed with it from worm and rottenness. Oil of cedar was used by the
ancient Egyptians for preserving their mummies. Tar and linseed oil were
also recommended by him. The image of the goddess Diana, at Ephesus,
was saturated with olive and cedar oils; also the image of Jupiter, at
Rome; and the statues of Minerva and Bacchus were impregnated with oil of
spikenard.
The idea of preserving wood by the action of oil is therefore by no means
new; but it is somewhat curious that the earliest modern processes should
also be by means of oil. The _oils most proper_ to be used are _linseed_,
_rapeseed_, or almost any of the vegetable fixed oils. Oak wood, rendered
entirely free from moisture, and then immersed in linseed oil, is said
to be thus prevented from splitting: the time of immersion depending on
the size, &c. Palm oil is preferable to whale oil, because impregnation
with the latter, although in many instances eligible, causes wood to
become brittle. It is, however, probable that whale oil, when combined
with other substances, such as litharge, coal pitch, or charcoal,
may lose much of that effect. As cocoa-nut oil, which is, under low
temperature, like the oil expressed from the nuts of the palm tree, is
known to be highly preservative of timber and metallic fastenings, we may
expect the same result from the latter, and thereby avoid that extreme
dryness and brittleness of the timber which Mr. Strange complained of
in the Venetian ships that had been seasoned for many years in frame
under cover. Cocoa-nut oil beat up with shell lime or _chunam_, so as to
become putty, and afterwards diluted with more oil, is used at Bombay and
elsewhere as a preservative coat or varnish to plank. It cannot become
a varnish without the addition of some essential oil; and the oil of
mustard is used; which, of course, will produce the desired effect. In
the first volume of the Abbé Raynal, on the European settlements in the
East and West Indies, he mentions that an oil was exported from Pegu for
the preservation of ships; but as he does not say what oil, no conclusion
can be drawn further than as to the probability of its being one of those
already noticed.
Experience has proved that even _animal oils_ are so far injurious
to timber as to _render it brittle_, whilst they preserve it from
rottenness; and that, on the other hand, a mineral salt more or less
combined with fatty substances does not produce that effect. The staves
of whale-oil casks become quite brittle, whilst those of beef, pork,
and tallow barrels remain tough and sound. Ships _constantly_ in the
Greenland trade have their timbers and planks preserved so far as they
have become impregnated with whale oil.
Experiments with fish oil prove that of itself, unless exposed to sun and
air, it may be injurious; that it loosens the cohesion of timber; but
that _animal fat_, combined _with saline matter_, _is preservative_.
Fish oil used alone is ineligible, because capable of running into the
putrefactive process, unless as a thin outside varnish. In hard, sound
timber, it will hardly enter at all; and if poured into bore-holes in the
heads of timbers, it will insinuate itself into the smallest rents or
cracks, and waste through them. Used alone, or with any admixture, it is
absorbed and dried quickly on wood in a decomposing state or commencing
to be dry rotten. Used with litharge, it dries after some days; but
with lamp-black it has scarcely so much tendency to dry as when used
alone. Paint of fish oil and charcoal dries very quickly where there is
absorption, and the charcoal extends its oxidating or drying effect to
the fish oil in its vicinity.
We give the following to prove what we have written, and also to serve as
an example for those who wish to try experiments:--
EXPERIMENTS ON FISH OIL.
June 9.--Upon a piece of old oak scantling, with its alburnam
on one side in a state of decay, fish oil was poured several
times, viz. on this day, on June 25, and July 3, which it rapidly
absorbed in the decayed part.
July 26.--It was payed (or mopped) with fish oil and charcoal
powder, and the following day it was put under an inverted cask.
October 1.--The end of this piece was covered with a greenish
mould. _This proves that fish oil must be injurious, except where
exposed to sun and air to dry it._
A compound of fixed oils and charcoal is liable to inflame, but as a thin
covering or pigment it may not be so.
The _petroleum_ oil-wells, near Prome, in Burmah, have been in use from
time immemorial. Wood, both for ship-building and house-building, is
invariably saturated or coated with the product of those wells; and
it is stated that the result is _entire immunity from decay_ and the
ravages of the white ant. At Marseilles, and some other ports in the
Mediterranean, it used to be the practice to run the petroleum, which
is obtained near the banks of the Rhone, into the vacancies between the
timbers of the vessels, to give them durability. It was sometimes, for
the conjoint purpose of giving stability and duration to vessels, mixed
with coarse sand or other extraneous matters, and run in whilst hot
between the ceiling and bottom plank, where it filled up the vacancies
between the timbers in the round of their bottoms, excepting where
necessary to be prevented. The great objection to the use of petroleum is
its inflammability. _Creosote_, its great rival for wood preserving, is
also inflammable, and not so agreeable in colour; but it is _considerably
cheaper_, which is an important matter.
As we are now about to enter upon the subject of patent processes, &c.,
it appears desirable to lay down certain principles at the commencement,
in order to assist the reader as much as possible.
Almost every chemical principle or compound of any plausibility has been
suggested in the course of the last hundred and fifty years; but the
multiplicity and contradiction of opinions form nearly an inextricable
labyrinth. To commence.
1st. It seems obvious that _the sooner the sap is wholly removed from the
wood the better_, _provided the woody fibre solidifies without injury_.
2nd. That _the wood should be impregnated with any strongly antiseptic
and non-deliquescent matter_, _which must necessarily be in solution when
it enters the wood_. No deliquescent remedy is eligible, because moisture
is injurious to metallic fastenings.
3rd. _The wood should be first dried, and its pores then closed with
any substance impervious to air and moisture, and at the same time
highly repellant to putrescency._ The most essential requisites in a
preservative of timber being a disposition to _dryness_, and a tendency
to resist _combustion_ as far as consistently obtainable.
4th. _Any process to be successful ought not to be tedious, very
difficult, or too expensive._ These are important elements in the success
of any patent.
Very little is known of any preservative process previous to the year
1717, when directions were given by the Navy authorities to _boil_
treenails, and dry them before they were used. But whether the custom had
prevailed before this time, or whether their strength and durability were
increased by it, there are no means of ascertaining. It does not appear
that any substance was put into the water to decompose the juices; but
as they are soluble in warm water, perhaps the power of vegetation might
have been destroyed without it.
In 1737 Mr. Emerson patented a process of saturating timber with _boiled
oil_, mixed with poisonous substances; but his process was very little
used. This, we believe, was the _first_ patent on wood preserving.
About 1740, Mr. Reid proposed to arrest decay by means of a certain
_vegetable acid_ (probably pyroligneous acid). The method of using it was
by simple immersion.
In 1756, Dr. Hales recommended that the planks at the water-line of ships
should be soaked in _linseed oil_, to prevent the injury to which wood
is subject when alternately exposed to wet and dry; and indeed, many
ships were built in which a hollow place was cut in one end of each beam
or sternpost, which might constantly be kept filled with _train oil_.
Amongst other ships so constructed, the ‘Fame,’ 74, may be mentioned.
When, after some years, this ship was repaired, it was found that as
far as the oil had penetrated, namely, from 12 to 18 inches from the
end, the wood was quite sound, whilst the other parts were more or less
decayed. The Americans used to hollow out the tops of their masts in the
form of cups or basins; bore holes from the end a considerable way down
the masts; pour oil into these; cover them over with lead; and leave the
oil to find its way down the capillary vessels to the interior of the
timber.[7]
In 1769, Mr. Jackson, a London chemist, with a view to the prevention
of decay, obtained permission to prepare some timber to be used in the
national yards, by immersing it in a solution of _salt water_, _lime_,
_muriate of soda_, _potash_, _salts_, &c., the result of which dose was,
that several frigates in the Navy subjected to the process were rendered
more perishable than if they had been constructed of unprepared timber.
The solution was filtered into the wood partly by means of holes made in
it. Chapman proposed a similar method of preserving the frames of ships,
viz. by boring holes in the timbers, and pumping a _solution of copperas_
in water into them. He believed every part of the vessel would thus be
impregnated.
Mr. Jackson also prepared the frame of the ship ‘Intrepid’ with another
solution. The ship lasted many years. Bowden thought it was a _solution
of glue_. Chapman suggested _slaked lime_, thinned with a weak _solution
of glue_ for mopping the timbers of a ship.
Shortly after Mr. Jackson’s process was started, Mr. Lewis attempted
to accomplish the preservation of timber by placing it surrounded by
pounded lime, in spaces below the “surface of the earth.” The use of lime
has also been advocated by Mr. Knowles, Secretary of the Committee of
Surveyors of the Navy, who has written an able work on the ‘Means to be
taken to Preserve the British Navy from Dry Rot’ (1821).
Between 1768 and 1773 a practice prevailed of saturating ships with
common salt; but this was found to cause a rapid corrosion of the iron
fastenings, and to fill the vessels between decks with a constant damp
vapour. In ‘Nicholson’s Journal,’ No. 30, there is an article signed
_Nauticus_ on this subject. Vessel owners had long ago observed that
those ships which have early sailed with cargoes of salt are not attacked
by dry rot. Indeed, several instances are attested of vessels whose
interiors were lined with fungi having all traces of the plant destroyed
by accidental or intentional sinking in the sea. Acting on such hints,
a trader of Boston, U. S., salted his ships with 500 bushels of the
chloride, disposed as an interior lining, adding 100 bushels at the end
of two years. Such an addition of dead weight is sufficient objection to
a procedure which has other great disadvantages. Salt should never be
applied as an antidote against the dry rot, on account of its natural
powers of attracting moisture from the atmosphere, which would render
apartments almost uninhabitable, from their continual dampness. Those who
have lived for any length of time in a house at the sea-side, the mortar
of which has been partly composed of sea sand, will have observed the
moist state of the paper, plastering, &c., in wet weather. Bricks made
with sea sand are objectionable.
_Salt water_ seasoning has already been referred to in the last chapter,
but as it is so closely connected with salt seasoning, the further and
final consideration of salt water seasoning may be fitly dealt with
here. Salt water will not extract the juices from the timber like fresh
water. It is only by destroying the vegetation that salt water can be
advantageous, but it would require a very long time to impregnate large
timber to the heart so as to destroy vegetation. It is well known that
wood is softened, and in time decomposed, by extreme moisture. Fifty
years since, the master builder at Cronstadt complained that the oak from
Casan, which was frequently wet from different causes in its passage of
three years to Cronstadt, was so water-soaked as never to dry; and also
from the information of Mr. Strange, it appears “that the practice at
Venice of the fresh-cut timber being thrown into salt water, prevents
its ever becoming dry in the ships, and that the salt water rusted and
corroded the iron bolts.” In fine, vessels built with salt water seasoned
wood are perfect hygrometers, being as sensible to the changes of the
moisture of the atmosphere as lumps of rock salt, or the plaster of
inside walls where sea sand has been used.
In Ceylon, the timber of the female palm tree is much harder and blacker
than that of the male, inasmuch as it brings nearly triple its price.
The natives are so well aware of the difference that they resort to the
devise of immersing the male tree in _salt water_ to deepen its colour,
as well as add to its weight.
Vessels impregnated with _bay salt_, or the large grained salt of
Leamington or of Liverpool (pure muriate of soda), will possess decided
advantages; as also will vessels that have been laden with _saltpetre_,
if it has been dispersed amongst their timbers.
Ships (the timbers of which had been previously immersed in salt water)
have been broken up after a few years’ service, and the floor timbers
taken out quite sound: but when exposed to the sun and rain in the summer
months, their albumen has been in a decomposed or friable state.
By the answers to queries given to Mr. Strange, the British Minister at
Venice, in or about 1792, it appears that several of the Venetian ships
of war had then lain under sheds for fifty-nine years; some in bare
frames, and others planked and caulked: that these ships show no outward
marks of decay; but their timbers have shrunk much, and _become brittle_;
that some of the most intelligent ship builders were of opinion that
great prejudice had arisen from the prevalent custom of throwing the
timber fresh cut into salt water, and letting it lie there until wanted;
that afterwards it dried, and withered on the outside, under the sheds,
while the inside, being soaked with salt water, rotted before it became
dry; and this was one reason, amongst others, why Venetian ships, though
built of good timber, lasted so short a time; for the salt moisture not
only rots the inside of the beams and timbers, but of course rusts and
corrodes the iron bolts.
_Salt water_, _sea-sand_, and _sea-weed_ are now used for seasoning
“jarrah” wood in Western Australia. This wood is considered a first-class
wood for ship-building, but it is somewhat slow to season, and if exposed
before being seasoned it is apt to “fly” and cast. The method adopted
is as follows: The logs are thrown into the sea, and left there for a
few weeks; they are then drawn up through the sand, and after being
covered with sea-weed a few inches deep, are left to lie on the beach,
care being taken to prevent the sun getting at their ends. The logs are
then left for many months to season. When taken up they are cut into
boards 7 inches wide, and stacked, so as to admit of a free circulation
of air round them, for five or six months before using them. Sea-weed or
sea-ware, cast upon the shores, contains a small quantity of carbonate
of soda, and a large proportion of nitrogenous and saline matters, with
earthy salts, in a readily decomposable state. They also contain much
soluble mucilage. The practice of seasoning timber by heating it in a
_sand bath_ was formerly adopted by the Dutch, and by the Russians in
building boats. Mr. Thomas Nichols (in a letter to Lord Chatham, when
First Lord of the Admiralty) states “that the same end, viz. preservation
of timber from decay, might probably be acquired by burying the timber in
sand, which acts as an artificial sap,” in the same manner as mentioned
in Townsend’s ‘Travels through Spain,’ to be used with the masts of ships
of war at Cadiz.
_Peat moss_ has been recommended (because the sulphates of iron, soda,
and magnesia are found in it), but it failed when tried.
With reference to Mr. Lewis’s proposal to preserve wood by means of
lime, it must be remembered that _quicklime_, with damp, has been found
to accelerate putrefaction, in consequence of its extracting carbon;
but when dry, and in such large quantities as to absorb all moisture
from the wood, _the wood is preserved_, _and the sap hardened_. Vessels
_long_ in the lime trade have afforded proof of this fact; and we have
also examples in plastering-laths, which are generally found sound and
good in places where they have been dry. Whitewash or _limewater_ has
been strongly recommended for use between the decks of ships, as being
unfavourable to vegetation: it should be renewed at intervals of time,
according to circumstances. It has been applied with good effect to the
joists and sleepers of kitchen floors; but to be effectual it should be
occasionally renewed. Effete, or re-carbonated lime, is injurious to
timber, like other absorbent earths; so also are calcareous incrustations
formed by the solution of lime in water, as appears from Von Buch’s
‘Travels in Norway,’ in which he says, “that in the fishing country (near
Lofodden, beyond the Arctic circle) the calcareous incrustations brought
by water, filtering through a bed of shells, soon cause the vessels and
wood to be covered with and destroyed by green fungi.” The ends of joists
of timber inserted in walls are frequently found rotten; and where not
so, it may probably be owing to the mortar having been made with hot
lime, and used immediately, or to the absence of moisture. It does not
appear practicable to use limewater to any extent for preserving timber,
because water holds in solution only about ⅟500th part of lime, which
quantity would be too inconsiderable; it, however, renders timber more
durable, but at the same time very hard and difficult to be worked (p.
73).
Vessels constantly in the _coal_ trade have generally required little
repair, and have lasted until in the common course of things they were
lost by shipwreck. This must be owing to the martial pyrites which abound
in all coals; and also from the sulphuric acid arising from the quantity
of coal dust which finds its way through the seams of the ceiling, and
adheres to the timber and planks.
In 1779, M. Pallas, in Russia, proposed to steep wood in _sulphate of
iron_ (green vitriol) until it had penetrated deeply, _and_ then in
_lime_ to precipitate the vitriol. Neumann, in his first volume of
‘Chemistry,’ on the article green vitriol, says, “That in the Swedish
transactions this salt is recommended for preserving wood, particularly
the wheels of carriages, from decay.
“When all the pieces are fit for being joined together, they are directed
to be boiled in a solution of vitriol for three or four hours, and then
kept for some days in a warm place to dry. It is said that the wood
by this preparation becomes so hard and compact that moisture cannot
penetrate it, and that iron nails are not so apt to be destroyed in this
vitriolated wood as might be expected, _but last as long as the wood
itself_.”
In 1780 the marcasite termed by the miners _mundic_, found in great
abundance in the tin mines in Devonshire and Cornwall, was employed, in
a state of fusion, to eradicate present and to prevent the future growth
of dry rot; but whether its efficacy was proved by time is not known. A
garden walk where there are some pieces of mundic never has any weeds
growing; the rain that falls becomes impregnated with its qualities, and
in flowing through the walk prevents vegetation.
In 1796 Hales proposed to _creosote_ the treenails of ships: this was
forty-two years previous to Bethell’s patent for creosoting wood.
About the year 1800, the Society of Arts’ building in the Adelphi,
London, being attacked by dry rot, Dr. Higgins examined the timbers,
caused some to be removed and replaced by new, and the remainder to be
scraped and washed with a solution of _caustic ammonia_, so as by burning
the surface of the wood to prevent the growth of fungi.
At the commencement of the present century, a member of the Royal Academy
of Stockholm called attention to the use of _alum_ for preserving wood
from fire. He says, in the Memoirs of that Academy, “Having been within
these few years to visit the alum mines of Loswers, in the province of
Calmar, I took notice of some attempts made to burn the old staves of
tubs and pails that had been used for the alum works. For this purpose
they were thrown into the furnace, but those pieces of wood which had
been _penetrated_ by the alum did not burn, though they remained for
a long time in the fire, where they only became red; however, at last
they were consumed by the intenseness of the heat, but they yielded no
flame.” He concludes, from this experiment, that wood or timber for the
purpose of building may be secured against the action of fire by letting
it remain for some time in water wherein vitriol, alum, or any other salt
has been dissolved which contains no inflammable parts.
In Sir John Pringle’s Tables of the antiseptic powers of different
substances, he states _alum_ to be thirty times stronger than sea-salt;
and by the experiments of the author of the ‘Essai pour servir à
l’Histoire de la Putréfaction,’ metallic salts are much more antiseptic
than those with earthy bases.
In 1815 it occurred to Mr. Wade that it would be a good practice to fill
the pores of timber with _alumine_, or selenite; but two years after,
Chapman observed, “Impregnation of ships’ timbers with a _solution of
alum_ occurred to me about twenty years since, because on immersion in
sea-water the alumine would be deposited in the pores of the timber; but
I was soon informed of its worse than inutility, by learning that the
_experiment had been tried_, and, in place of preserving, had _caused the
wood to rot speedily_. Impregnation with _selenite_ has been tried in elm
water-pipes. On precipitation from its solvent it partially filled the
pores, and hardened the wood, but _occasioned speedy rottenness_.” If,
by using a _solution of alum_ to render wood uninflammable, we at the
same time cause it to _rot speedily_, it becomes a question _whether the
remedy is not worse than the disease_. Captain E. M. Shaw, of the London
Fire Brigade, in his work, ‘Fire Surveys’ (1872), recommends _alum and
water_. Probably he only thought of fire, and not of rotting the wood.
The alum question does not appear to be yet satisfactorily settled.
While upon the subject of uninflammable wood, we may state that in 1848,
upon Putney Heath (near London), by the roadside, stood an obelisk, to
record the success of a discovery made in the last century of the means
of building a house which no ordinary application of ignited combustibles
could be made to consume: the obelisk was erected in 1786. The inventor
was Mr. David Hartley, to whom the House of Commons voted 2500_l._, to
defray the expenses of the experimental building, which stood about one
hundred yards from the obelisk. The building was three stories high, and
two rooms on a floor. In 1774, King George the Third and Queen Charlotte
took their breakfast in one of the rooms, while in the apartment beneath
fires were lighted on the floor, and various inflammable materials were
ignited to attest that the rooms above were fire-proof. Hartley’s secret
lay in the floors being double, and there being interposed between the
two boards sheets of laminated iron and copper, not thicker than stout
paper, which rendered the floor air-tight and thereby intercepted the
ascent of the heated air; so that, although the inferior boards were
actually charred, the metal prevented the combustion taking place in the
upper flooring. Six experiments were made by Mr. Hartley in this house
in 1776, but we cannot ascertain any particulars about them, or any
advantages which accrued to the public from the invention, although the
Court of Common Council awarded him the freedom of the City of London for
his successful experiments.
In 1805 Mr. Maconochie proposed to saturate with resinous and oily
matters inferior woods, and thus render them more lasting. This proposal
was practically carried out in 1811 by Mr. Lukin, who constructed a
peculiar stove for the purpose of thus impregnating wood under the
influence of an increased temperature. The scheme, however, had but
very partial success, for either the heat was too low and the wood was
not thoroughly aired and seasoned, or it was too high and the wood was
more or less scorched and burnt. Mr. Lukin buried wood in _pulverized
charcoal_ in a heated oven, but the fibres were afterwards discovered to
have started from each other. He next erected a large kiln in Woolwich
dockyard, capable of containing 250 loads of timber, but an explosion
took place on the first trial, before the process was complete, which
proved fatal to six of the workmen, and wounded fourteen, two of
whom shortly afterwards died. The explosion was like the shock of an
earthquake. It demolished the wall of the dockyard, part of which was
thrown to the distance of 250 feet; an iron door weighing 280 lb. was
driven to the distance of 230 feet; and other parts of the building were
borne in the air upwards of 300 feet. The experiment was not repeated.
Mr. Lukin was not so fortunate in 1811 as in 1808, for in the latter
year he received a considerable reward from the Government for what was
considered a successful principle of ventilating hospital ships.
In 1815 Mr. Wade recommended the impregnation of timber with resinous or
oleaginous matter (preferring linseed oil to whale oil) or with _common
resin_ dissolved in a lixivium of _caustic alkali_, and that the timber
should afterwards be plunged into water acidulated with any cheap acid,
or with alum in solution. He considered that timber impregnated with oil
would not be disagreeable to rats, worms, cockroaches, &c., and that the
contrary was the case with resin. He also recommended the impregnation of
timber with sulphate of _copper, zinc, or iron_, rejecting deliquescent
salts, as they corrode metals.
In 1815 Mr. Ambrose Boydon, of the Navy Office, strongly recommended
that the timber, planks, and treenails of ships should be first boiled
in _limewater_ to correct the acid, and that they afterwards should be
boiled in a _thin solution of glue_, by which means the pores of the wood
would be filled with a hard substance insoluble by water, which would not
only give the timbers durability, by preventing vegetation, but increase
their strength. Glue, he thought, might be used without limewater, or
glue and limewater mixed together.
In 1817 Mr. William Chapman published the result of various experiments
he had made on wood with _lime_, _soap_, and _alkaline_ and _mineral
salts_. He recommended a solution of a pound of _sulphate of copper_ or
blue vitriol (at that time 7_d._ per pound) dissolved in four ale gallons
of rain water, and mopped on hot over all the infected parts, or thrown
over them in a plentiful libation. He also recommended one ounce of
_corrosive sublimate_ (then 6_s._ per pound) to a gallon of rainwater
applied in the same manner to the infected parts. For weather-boarded
buildings he considered one or more coats of thin _coal tar_, combined
with a small portion of _palm oil_, for the purpose of preventing their
tendency to rend, to be a good preservative.
Messrs. Wade, Boydon, and Chapman published works on dry rot about this
time.
In 1822 Mr. Oxford took out a patent for an improved method of preventing
“decay of timber,” &c. The process proposed was as follows: “The
essential _oil of tar_ was first extracted by distillation, and at the
same time saturated with _chlorine gas_. Proportions of _oxide of lead_,
_carbonate of lime_, and _carbon of purified coal tar_ well ground,
were mixed with the oil, and the composition was then applied in thick
coatings to the substances intended to be preserved.”
On 31st March, 1832, Mr. Kyan patented his process of _corrosive
sublimate_ (solution of the _bi-chloride of mercury_) for preventing dry
rot; which process consisted as follows: A solution of the corrosive
sublimate is first made, and the timber is placed in the tank. The wood
is held down in such a way, that when immersed on the fluid being pumped
in, it cannot rise, but is kept under the surface, there being beams
to retain it in its place. There it is left for a week, after which
the liquor is pumped off, and the wood is removed. This being done,
the timber is dried, and said to be prepared. Sir Robert Smirke was
one of the first to use timber prepared by Kyan, in some buildings in
the Temple, London; and he made some experiments on timber which had
undergone Kyan’s process. He says, “I took a certain number of pieces
of wood cut from the same log of yellow pine, from poplar, and from the
common Scotch fir; these pieces I placed first in a cesspool, into which
the waters of the common sewers discharged themselves; they remained
there six months; they were then removed from thence, and placed in a
hotbed of compost under a garden-frame; they remained there a second six
months; they were afterwards put into a flower border, placed half out of
the ground, and I gave my gardener directions to water them whenever he
watered the flowers; they remained there a similar period of six months.
I put them afterwards into a cellar where there was some dampness, and
the air completely excluded; they remained there a fourth period of six
months, and were afterwards put into a very wet cellar. Those pieces of
wood which underwent Kyan’s process are in the same state as when I first
had them, and all the others to which the process had not been applied
are more or less rotten, and the poplar is wholly destroyed.
“I applied Kyan’s process to yellow Canadian pine about three years ago,
and exposed that wood to the severest tests I could apply, and it remains
uninjured, when any other timber (oak or Baltic wood) would certainly
have decayed if exposed to the same trial, and not prepared in that
manner.
“As another example of the effect of the process, I may mention that
about two years ago, in a basement story of some chambers in the Temple,
London, the wood flooring and the wood lining of the walls were entirely
decayed from the dampness of the ground and walls, and to repair it under
such circumstances was useless. As I found it extremely difficult to
prevent the dampness, I recommended lining the walls and the floor with
this prepared wood, which was done; and about six weeks ago I took down
part of it to examine whether any of the wood was injured, but it was
found in as good a state as when first put up. I did not find the nails
more liable to rust.’
“I have used Kyan’s process in a very considerable quantity of paling
nearly three years ago; that paling is now in quite as good a state as it
was, though it is partly in the ground. It is yellow pine. Some that I
put up the year before, without using Kyan’s process (yellow pine), not
fixed in the ground, but close upon it, is decayed.”
This evidence, by such an experienced architect as the late Sir Robert
Smirke was, is certainly of great value in favour of Kyan’s process.
The recorded evidence upon the efficiency of this mode of treating timber
for its preservation is somewhat contradictory. On the Great Western
Railway 40,000 loads were prepared, at an expenditure of 1¾ lb. of
sublimate to each load, the timber, 7 inch, being immersed for a period
of eight days, and the uniformity of the strength of the solution being
constantly maintained by pumping. Some samples of this timber, after six
years’ use as sleepers on the railway, were found “as sound as on the day
on which they were first put down.” This timber was prepared by simple
immersion only, without exhaustion or pressure. Some of the sleepers
on the London and Birmingham Railway, on the other hand, which had been
Kyanized three years only, were found absolutely rotten, and Kyan’s
process was there consequently abandoned.
This process is said to cost an additional expense to the owner of from
fifteen to twenty shillings per load of timber. Mr. Kyan at first used
1 lb. of the salt in 4 gallons of water, but it was found that the wood
absorbed 4 or 5 lb. of this salt per load; more water was added to lessen
the expense, until the solution became so weak as in a great measure to
lose its effect.
Simple immersion being found imperfect as a means of injecting the
sublimate, attempts were afterwards made to improve the efficiency of the
solution by _forcing_ it into the wood. Closed tanks were substituted
for the open ones, and forcing pumps, &c., were added to the apparatus.
The pressure applied equalled 100 lb. on the square inch. With this
arrangement a solution was made use of having 1 lb. of the sublimate to
2 gallons of water; and it was found that three-fourths of this quantity
sufficed for preparing one load of timber. The timber was afterwards
tested, and it was ascertained that the solution had penetrated to the
heart of the logs. Mr. Thompson, the Secretary to Kyan’s Company, stated,
in March, 1842, that experience had proved “that the strength of the
mixture should not be less than 1 lb. of sublimate to 15 gallons of
water; and he had never found any well-authenticated instance of timber
decaying when it had been properly prepared at that strength.” As much
as 1 in 9 was not unfrequently used. Kyan’s process is now but very
rarely used; Messrs. Bethell, of King William Street, London, adopt it
when requested by their customers. We have given the statements which
have been made for and against this patent, but after a lapse of forty
years it is difficult to reconcile conflicting statements.
[Illustration: PATENT PRESERVATIVE SYSTEM.
Horizontal Section of Mr. Kyan’s Original Tank and Cistern.
A. _Bottom of Tank._
B. _¾″ Iron bolts to connect the planks which form the sides and end of
the Tank and Cistern._
C. _The Cistern which contains the solution._
D. _The Tank._
E. _Pump for raising the solution from tank into Cistern._
F. _Tap for conveying the solution from Cistern to Tank._
G. _Wood sleepers to carry Tank and Cistern._]
Although Mr. Kyan invented his process in 1832, Sir Humphrey Davy had
previously used and recommended to the Admiralty, and Navy Board, a
weak solution of the same thing to be used as a wash where rot made
its appearance: on giving his opinion upon Mr. Lukin’s process, that
eminent chemist observed, “that he had found corrosive sublimate highly
antiseptic, and preservative of animal and vegetable substances, and
therefore recommended rubbing the surface of timber with a solution
of it.” In 1821 Mr. Knowles, of the Navy Office, referred to the use
of corrosive sublimate for timber. In fact, it was used in 1705, in
Provence (France), for preserving wood from beetles. Kyan, however, was
the first to apply it to any extent. In the years 1833 to 1836, at the
Arsenal, Woolwich, experiments were instituted, having for their object
the establishing, or otherwise, the claims of Kyan’s system; the results
of which were of a satisfactory nature. Dr. Faraday has stated that the
combination of the materials used was not simply mechanical but chemical;
and Captain Alderson, C.E., having experimented upon some specimens
of ash and Christiana deal, found that the rigidity of the timber was
enhanced, but its strength was in some measure impaired; its specific
gravity being also in some degree diminished.[8] Kyan’s process is said
by some to render the wood brittle.
Mr. Kyan considered that the commencement of rot might be stopped or
prevented by the application of corrosive sublimate, in consequence
of the chemical combination which takes place between the corrosive
sublimate and those albuminous particles which Berzelius and others of
the highest authority consider to exist in and form the essence of wood;
which, being the first parts to run to decay, cause others to decay with
them. By seasoning timber in the ordinary way, the destructive principle
is dried, and under common circumstances rendered inert. But when the
timber is afterwards exposed to great moisture, &c. (the fermentative
principle being soluble when merely dried), it will sometimes be again
called into action. Kyan’s process is said not only altogether to destroy
this principle and render it inert, but, by making it solid and perfectly
insoluble, to remove it from the action of moisture altogether. It thus
loses its hygrometric properties, and, therefore, prepared or patent
seasoned timber is not liable to those changes of atmosphere which affect
that which is seasoned in the common way. All woods, including mahogany
and the finest and most expensive wood, may be seasoned by Kyan’s process
in a very short space of time, instead of the months required by the
ordinary methods.
The reader will find a great deal about Kyan’s system in the ‘Quarterly
Review,’ April, 1833; and about proposals for using chloride of mercury
for wood, ‘Memoirs of the Academy of Dijon,’ 1767; ‘Bull. des Sciences
teen.,’ v. ii., 1824, Paris; and ‘Bull. de Pharm.,’ v. 6, 1814, Paris.
It is well known that Canadian timber is much more liable to decay than
that grown in the northern parts of Europe, and for this reason is never
extensively used in buildings of a superior description. The principle
of decay being destroyed by Kyan’s process as above described, this
objection no longer exists, and this kind of timber may therefore now be
employed with as great security as that of a superior quality and higher
price. The same observation applies with great force to timber of British
growth, particularly to that of Scotland, much of which is considered as
of little or no value for durable purposes, on account of its extreme
liability to decay, whether in exposed situations or otherwise. The
process invented by Kyan might therefore render of considerable value
plantations of larch, firs of all kinds, birch, elm, beech, ash, poplar,
&c.
Cost of process in 1832, 1_l._ per load of 50 cubic feet of timber.
Mr. W. Inwood, the architect of St. Pancras Church, London, reported
favourably of Kyan’s process. On 22nd February, 1833, Professor Faraday
delivered a lecture at the Royal Institution, London, on Kyanizing
timber; and on 17th April, 1837, he reported that Kyan’s process had not
caused any rusting or oxidation of the iron in the ship ‘Samuel Enderby,’
after the ship had been subjected to this process, and had been on a
three years’ voyage to the South Sea fisheries; and in the same year,
viz. 1837, Dr. Dickson delivered a lecture at the Royal Institute of
British Architects on dry rot, recommending Kyan’s process.
Five years after Mr. Kyan’s invention, viz. in 1837, a Mr. Flocton
invented a process for preventing decay, by saturating timber with
_wood-tar_ and _acetate of iron_, but little is known of this invention:
we believe it was a failure.
During the same year Mr. Flocton’s process was made known, a Frenchman
named Letellier recommended saturating timber in a solution of _corrosive
sublimate_, and when dry, into one of _glue_, _size_, &c.[9]
During this year Mr. Margary took out his patent for applying _sulphate
of copper_ to wood. We propose to describe Margary’s process further on:
we do not think he received any medals for it.
We now arrive at the modern _creosoting_ process, which was brought
to perfection by the late Mr. John Bethell. Mr. Bethell’s process of
creosoting, or the injection of the heavy oil of tar, was first patented
by him on July 11th, 1838.[10] It consists in impregnating the wood
throughout with oil of tar, and other bituminous matters containing
creosote, and also with pyrolignite of iron, which holds more creosote in
solution than any other watery menstruum. Creosote, now so extensively
used in preserving wood, is obtained from coal tar, which, when submitted
to distillation, is found to consist of pitch, essential oil (creosote),
naphtha, ammonia, &c. In the application of the oil of tar for this
purpose, it is now considered to be indispensable that the ammonia be
got rid of; otherwise the wood sometimes becomes brown and decays, as
may be constantly seen in wood coated with the common oil tar. The kind
of creosote preferred by continental engineers and chemists, and also by
the late Mr. John Bethell himself, is _thick_, and rich in _naphthaline_.
Some English chemists now seem to prefer the thinnest oil, which contains
no naphthaline, but a little more carbolic acid; the crude carbolic acid
would vary from 5 to 15 per cent.: no engineer has ever required more
than 5 per cent. of crude carbolic acid in creosote. The thinner oil
appears to be more likely to be drawn out of the wood by the heat of the
sun or absorption in powdery soil, and is more readily dissolved out by
moisture.
Mummies many thousands of years old have evidently been preserved on
the creosoting principle, and from observing the mummies the process
of creosoting suggested itself to Mr. Bethell. The ancient Egyptians,
whether from the peculiarity of their religious opinions, or from the
desire to shun destruction and gain perpetuity even for their dead
bodies, prepared the corpses of their deceased friends in a particular
way, viz. by coagulating the albumen of the various fluids of the body
by means of creosote, cedar oil, salt, and other substances, and also
by excluding the air. How perfectly this method has preserved them the
occasional opening of a mummy permits us to see. A good account of the
operation is given in the chapter on mummies, in the second volume of
Egyptian Antiquities in the ‘Library of Entertaining Knowledge.’
By the process of creosoting the timber is rendered more durable, and
less liable to the attack of worms; but it becomes very inflammable;
that is, _when_ once alight burns quickly; in addition to which, the
disagreeable odour from timber so treated renders it objectionable for
being used in the building of dwelling-houses.
The action of the solutions in water of metallic salts is, if the mixture
is sufficiently strong, to coagulate the albumen in the sap; but the
fibre is left unprotected.
Creosote has the same effect of coagulating the albumen, whilst it fills
the pores of the wood with a bituminous asphaltic substance, which gives
a waterproof covering to the fibre, prevents the absorption of water, and
is obnoxious to animal life.
In cases where the complete preservation of timber is of vital
importance, and expense not a consideration, the wood should be first
subjected to Burnett’s process, and then creosoted; by which means it
would be nearly indestructible; the reason for this combined process
being, that the albumen or sap absorbs the creosote more readily than the
heart of the timber, which can, however, be penetrated by the solution of
chloride of zinc. Mr. John Bethell’s patent of 1853 recommends this in a
rather improved form. He says the timber should _first_ be injected with
metallic salts, then dried in a drying-house, then creosoted. By this
method, very considerable quantities both of metallic salt and creosote
can be injected into timber.
It has been stated that the elasticity of wood is increased by
creosoting; the heart-wood only decays by oxidation.
The wood should be dried previous to undergoing the process, as the
sapwood, otherwise almost useless, can be rendered serviceable, and for
piles for marine work whole round timber should be used, because the
sapwood is so much more readily saturated with the oil, and this prevents
the worms from making an inroad into the heart.
Mr. Bethell uses about 10 lb. of creosote per cubic foot of wood, and
he does not allow a piece of timber to be sent from his works without
being tested to ascertain if it has absorbed that amount, or an amount
previously agreed upon. We mention the latter statement, because it is
evident that all descriptions of wood cannot be made to imbibe the same
amount. This process is chiefly used for pine timber: yellow pine should
absorb about 11 lb. to the cubic foot, and Riga pine about 9 lb. The
quantity of oil recommended by the patentee, engineers, and others, is
from 8 to 10 lb. for land purposes, and about 12 lb. to the cubic foot
for marine. In this country, for marine the quantity does not exceed
12 lb.; but on the Continent, in France, Belgium, and Holland, the
quantity used is from 14 to 22 lb. (!) per cubic foot. The specifications
frequently issued by engineers for sleepers for foreign railways describe
them to be entirely of heart-wood, and then to be creosoted to the extent
of 10 lb. of the oil per cubic foot: this it is impossible to do, the
value of the process being in the retention of the sapwood.
It being ascertained a few years since that the centres of some sleepers
were not impregnated with the fluid, after the sleeper had been creosoted
to the extent of 10 lb. of creosote per cubic foot, Sir Macdonald
Stephenson suggested, as a means of obviating that defect, the boring
of two holes, 1 inch in diameter, through each sleeper longitudinally,
and impregnating up to 12 lb. or 14 lb. per cubic foot. By that means
the creosote would be sent all through the sleeper. The boring by hand
would be an expensive process, but by machinery it might be effected at a
comparatively small increased cost.
During the last twenty-five years an enormous quantity of creosoted
railway sleepers have been sent to India and other hot climates. The
native woods are generally too hard for penetration. On the great Indian
Peninsula Railway the native woods were so hard and close-grained that
they could not be impregnated with any preservative substance, sál wood
being principally used, into which creosote would not penetrate more
than one quarter of an inch. As regards creosoting wood in India, it
is moreover a costly process, owing to the difficulty and expense of
conveying creosote from England; iron tanks are necessary to hold the oil
when on board ship, and, being unsaleable in India, add to the expense.
English contractors often send piles to be creosoted which have been
taken from the timber docks. The large quantity of water they contain
resists the entrance of the oil, and the result is that a great deal of
timber is badly prepared because the contractors cannot obtain it dry.
In the best creosoting works the tank or cylinder is about 6 feet
diameter, and from 20 to 50 feet long. In some instances cylinders are
open at both ends, and closed with iron doors, so that sleepers or timber
entered at one end on being treated can be delivered finished at the
opposite end; but for all practical purposes one open end is sufficient,
as the oil when heated being of such a searching character it is a
difficult matter to get the doors perfectly air-tight, consequently they
are apt to leak during the time the pressure is being applied. Pipes are
led from the cylinder to the air and force pumps; the air is not only
extracted from the interior of the cylinder, but also from the pores of
the timber. When a vacuum is made, the oil, which is contained in a tank
below the cylinder, is allowed to rush in, and, as soon as the cylinder
is full, the inlet pipe is shut and the pressure pumps started to force
the oil into the wood; the pressure maintained is from 150 to 200 lb.
to the square inch, until the wood has absorbed the required quantity
of oil, which is learned by an index gauge fixed to the working tank
below. All cylinders are fitted with safety valves, which allow the oil
not immediately absorbed to pass again into the tank. The oil is heated
by coils of pipe placed in the tank, through which a current of steam is
passed from end to end, raising the temperature to 120°.
With regard to the cost of creosoting: half-round sleepers, being 9
feet long, 10 inches wide, and 5 inches thick, properly creosoted, are
worth about 4_s._ each; adzing for the chairs (done by machine) costs
6_s._ per 100. These prices, unfortunately, vary very much, according to
circumstances. The fir sleepers on the London and Birmingham Railway
cost 7_s._ 6_d._ each, and the patent preservative added 9_d._ more to
the expense, but they did not cost so much on other lines. A London
builder wrote to us in 1870, as follows: “Our price for creosoting
timber, &c., is 15_s._ per load of 50 cubic feet. Price of creosote,
2_d._ per gallon.”
By returns from the Leith Harbour Works it was shown that the average
quantity of creosote absorbed by the timber was 57⅞ gallons per load, or
577 lb. weight forced into 50 cubic feet of wood. Assuming the cost to be
15_s._ per load, and the creosote at 2_d._ per gallon, the creosote would
cost 9_s._ 8_d._, and the labour and profit 5_s._ 4_d._ per load of 50
cubic feet.
It is essential to observe that all methods of protecting timber depend
for their success upon the skilful and conscientious manner in which they
are applied; for, as they involve chemical actions on a large scale,
their efficiency must depend upon the observance of the minute practical
precautions required to exclude any disturbing causes. In the case of
creosoting: to distil the creosote, to draw the sap or other moisture
from the wood, and subsequently to inject the creosote in a proper
manner, it is necessary that the operations should be carried into effect
under the supervision of experienced persons of high character.
[Illustration: PATENT PRESERVATIVE SYSTEM.
Messrs. John Bethell and Cos. Timber preserving apparatus.]
Mr. Bethell’s process has been and still is being tested on the Indian
railways. According to Dr. Cleghorn, it appears that many of the
creosoted sleepers have, however, “been found decayed in the centre,
the interior portion being scooped out, leaving nothing but a deceptive
shell, in some instances not more than ½ inch in thickness,” but he
does not state whether the sleepers were prepared in England or in
India; because, if prepared in India, it is probable that some of the
hard Indian woods, into which it is not possible to get creosote or
any other preservative fluid, had been used. Mr. Burt, who has large
timber-preserving works in London for creosoting, stated about eight
years since, that after an experience of twenty years, during which
time he had sent over one million and a half sleepers to India alone,
besides having prepared many thousand loads of timber for other purposes,
he could safely assert that the instances of failure had been rare and
isolated.
A section of a piece of timber impregnated with creosote presents some
curious and very distinctive characteristics, according to the duration
of the process of injection and amount of tar injected. In every case
the injected tar follows the lines and sinuosities of the longitudinal
fibres. When injected in sufficient quantity it fills the pores
altogether; when, on the contrary, the process has been incompletely
performed, which, however, is generally sufficient, the tar accumulates
in the transverse sections, and plugs the channels that give access to
deleterious agents.
The experiments made by M. Melseuns on oaken blocks exposed to the fumes
of _liquid ammonia_ show that the conservating fluids follow the precise
course that would be taken by decay. In wood treated with creosote the
tar acts on the very parts first exposed to injury, and on the course
that would be taken by decay, which is thus rendered impossible. The
methods of injection suggested by M. Melseuns in 1845 did not answer
equally well with every kind of wood. After trying wooden blocks in
every sort of condition, dressed and in the rough, green and dry, sound
and decayed, M. Melseuns found that alder, birch, beech, hornbeam, and
willow were easily and completely impregnated; deal sometimes resisted
the process, the innermost layers remaining white; poplar and oak offered
a very great resistance--indeed, with poplar it was found necessary to
repeat the process.
The decay of sleepers, prepared and unprepared, will often depend on
their form. Three forms have been used: 1st, the half-round sleeper,
10 inches by 5 inches; these are now almost universally used; 2nd, the
triangular sleeper, about 12 inches wide on each side, used by Mr. Cubitt
on the Dover line, but since abandoned; and 3rd, the half square, 14
inches by 7 inches, used by Mr. Brunel and still in use. Mr. G. O. Maun,
in reporting on the state of the sleepers of the Pernambuco Railway,
states that fair average samples taken out on the 1st December, 1863
(laid in 1857), show that the half-round intermediate sleeper is in the
most perfect state of preservation; in fact, nearly as good as on the day
it was put down; while the square-sawn or joint sleeper has not withstood
the effects of the climate so well.
The kind of ballast in which it will be most advisable to lay the sleeper
is another important point to be attended to. About 12 miles of the
Pernambuco Railway are entirely laid with creosoted sleepers, principally
in white sand. In this description of ballast the half-round sleepers
have suffered, since the opening of the first section of the line in 1858
up to 1866, a depreciation of not more than 1 per cent., whilst the
square-sawn sleepers have experienced a depreciation of not less than
50 per cent. Had the latter been placed in wet cuttings with ballast
retentive of moisture, no doubt the whole of them would have required to
be renewed. Hence it is evident that fine open sand ballast, which allows
a free drainage during the rains, is best adapted for the preservation of
sleepers in the tropics: it has also been found to be the best in most
countries.
The number of testimonials given in favour of creosote is very large,
and are from the most eminent engineers of all countries, in addition
to which Mr. Bethell has received several medals at international
exhibitions. The English engineers include Messrs. Brunel, Gregory,
Abernethy, Ure, Hemans, Hawkshaw, and Cudworth; the French, MM. Molinos
and Forestier; the Dutch, Messrs. Waldorp, Freem, and Von Baumhauer; and
the Belgian, M. Crepin. The late Mr. Brunel expressly stated that, in his
opinion, well creosoted timbers would be found in a sound and serviceable
condition at the expiration of forty years. M. Forestier, French engineer
of La Vendée department, reporting to the juries of the French Exhibition
of 1867, cites a number of experiments he has lately tried upon many
pieces of creosoted and uncreosoted oak, elm, ash, Swedish, Norwegian,
and Dantzic red fir, Norway white fir, plane, and poplar, and shows that
in each case, except that of the poplar, the resistance of the wood both
to bending and crushing weight was much increased by creosoting.
Drs. Brande, Ure, and Letheby, also bear testimony to the efficacy of
this mode of preserving timber.
Creosoting has been extensively employed upon all the principal railways
in Great Britain. In England, upon the London and North Western,
North Eastern, South Eastern, Great Western, &c. In Scotland, on the
Caledonian, Great Northern, &c. In Ireland, on the Great Southern and
Western, Midland, &c. It has also been and is being employed in Belgium,
Holland, France, Prussia, India, and America.
Between the years 1838 and 1840, Sir William Burnett’s (formerly
Director-General of the Medical Department of the Navy) process was first
made known to the public.
This process consists of an injection of _chloride of zinc_ into timber,
in the proportion of about 1 lb. of the salt to about 9 or 10 gallons of
water, forced into the wood under a pressure of 150 lb. per square inch.
The late Professor Graham thus wrote of its efficiency: “After making
several experiments on wood prepared by the solution of chloride of zinc
for the purpose of preservation, and having given the subject my best
consideration, I have come to the following conclusions:
“The wood appears to be fully and deeply penetrated by the metallic salt.
I have found it in the centre of a large prepared block.
“The salt, although very soluble, does not leave the wood easily when
exposed to the weather, or buried in dry or damp earth. It does not
come to the surface of the wood like the crystallizable salts. I have
no doubt, indeed, that the greater part of the salts will remain in the
wood for years, when employed for railway sleepers or such purposes. This
may be of material consequence when the wood is exposed to the attacks
of insects, such as the white ant in India, which, I believe, would be
repelled by the poisonous metallic salt. After being long macerated in
cold water, or even boiled in water, thin chips of the prepared wood
retain a sensible quantity of the oxide of zinc; which I confirmed by Mr.
Toplis’ test, and observed that the wood can be permanently dyed from
being charged with a metallic mordant.
“I have no doubt, from repeated observations made during several years,
of the valuable preservative qualities of the solution of chloride
of zinc, as applied in Sir W. Burnett’s process; and would refer its
beneficial action chiefly to the small quantity of the metallic salt,
which is permanently retained by the ligneous fibre in all circumstances
of exposure. The oxide of zinc appears to alter and harden the fibre
of the wood, and destroy the solubility, and prevent the tendency to
decomposition of the azotised principles it contains by entering into
chemical combination with them.”
The Report of the Jury, which was drawn up by the Count of Westphalia, at
the Cologne International Agricultural Exhibition, in 1865, upon prepared
specimens of timber, has the following remarks on the chloride of zinc
process:
1st. That chloride of zinc is the only substance which thoroughly
penetrates the timber, and is at the same time the best adapted
for its preservation.
2nd. That the process of impregnating the wood after cutting is
more useful and rational than doing so while the tree is growing.
3rd. That red beech is the only wood which has been impregnated
in an uniform and thorough manner.
It should, however, be stated that the Jury had very slender evidence
presented to it respecting the creosoting process. The creosoted
specimens had been impregnated under the pressure of 60 lb. to 65 lb. per
square inch for three or four hours, and were consequently inefficiently
done; in England the pressure per square inch would have been at least
140 lb.
Drs. Brande and Cooper, of England, and Dr. Cleghorn, of India, also
wrote favourably of Sir W. Burnett’s process.
In 1847 a powerful cylinder, of Burnett’s construction, hermetically
closed, was laid down adjoining the sawmills in Woolwich dockyard. It
was found to admit the largest description of timber for the purpose of
having the moisture extracted, and the pores filled with chloride of
zinc. Three specimens of wood--English oak, English elm, and Dantzic
fir--remained uninjured in the fungus pit at Woolwich for five years;
while similar, but unprepared, specimens were all found more or less
decayed.
The cost of preparing timber by this process is 12_s._ per load, besides
2_s._ for landing and loading: 1 lb. of the material costing 1_s._, which
is sufficient for 9 or 10 gallons of water.
Sir W. Burnett and Co.’s works for hydraulic apparatus and tanks are at
Nelson Wharf, Millwall, Poplar; their office is at 90, Cannon Street,
London. Their terms are--
“For timber, round or square, including planks, deals, hop-poles,
paving-blocks, &c., against rot, 12_s._ per load of 50 cubic feet.
“For park palings, cabinet work, wine and other laths, as per
agreement.
“For railway sleepers, 9 feet long, 10 inches by 5 inches,
landing and reshipping included, 7_d._ each.
“For timber to be rendered uninflammable, 25_s._ per load.”
Sir W. Burnett’s firm now sell their patent concentrated solution at
5_s._ per gallon: each gallon must be diluted with 40 gallons of water,
according to the instructions in the licence, for which no charge is made.
The reader will probably have observed that this process is _considered_
to render timber uninflammable; then let us see what will be the cost of
obtaining a fire-proof house.
The principal building material which causes the destruction of our
houses by fire is wood--_combustible wood_. If, therefore, (as nearly
all our houses are “brick and timber” erections,) we render this wood
uninflammable, what will the cost be?
The following is an _approximate_ estimate of the extra expense,
including sundries, &c.:--
Timber and Deals. Cost of House. Additional expense.
Loads. £ £
25 1000 34
15 600 21
10 400 14
8 250 12
When will the Building Act compel us to use this table _in daily
practice?_
Although among the many attempts to preserve wood those in England have
proved the most successful, it should be mentioned that France, Germany,
and America have given much attention to the subject.
At the end of the last century Du Hamel and Buffon pointed out the
possibility of preserving wood, as well as the means of rendering it
unalterable. As early as 1758 Du Hamel made experiments on the vital
suction of plants, and made some curious observations on the different
rings of vegetable matter which absorb most liquid in different plants.
He also tried the effect of vital suction and pressure (of gravitation)
acting at the same time. His process was reviewed by Barral in 1842.
About 1784 M. Migneron invented a process about which little is now
known, but the wood was covered with certain fatty substances. Wood nine
years exposed to deterioration was improved by this process. M. Migneron
had the approval of Buffon, Franklin, and the Academies. His invention
was again brought into notice in 1807, when it was found that timber
which had been prepared by it in 1784, and exposed more than twenty
years, was quite sound.
In 1811 Cadet de Gassicourt made different kinds of wood imbibe vegetable
and mineral substances, and certain unguents: he used metallic salts
(iron, tin, &c.).
In 1813 M. Champy plunged wood into a bath of _tallow_ at 334°, and kept
it there two or three hours. His experiments were afterwards repeated by
Mr. Payne.
About the year 1832 it was proposed in America to apply _pyroligneous
acid_ to the surface of wood, or introduce it by fumigation.
Biot (who has written an excellent life of Sir Isaac Newton) remarked,
in 1831, that wood could be soaked by pressure; but his process of
penetrating it with liquids was imperfect, and his discovery remains
unapplied.
A Frenchman, of the name of Bréant, made about this time a discovery
which preceded Boucherie’s method, which is adopted to a great extent
in France. Bréant’s apparatus consisted of a very ingenious machine,
which, acting by pressure, caused liquids to penetrate to all points
of a mass of wood of great diameter and considerable length. He may
therefore be regarded as having solved the problem of penetration in
a scientific, though not in a practically applied, point of view. Dr.
Boucherie testified before the Académie des Sciences, in 1840, to
the merit of Bréant’s invention, which, with modifications by Payne,
Brochard, and Gemini, has been worked in France and England. This process
was recommended by Payne in 1840 and 1844, and imitated by him in France,
and later on by Yengat and Bauner, who used both _an air pump and a
forcing pump_. Bréant obtained three patents, viz. 1st, in 1831, to act
by pressure; 2nd, in 1837, by vital suction: and 3rd, in 1838, vacuum by
steam. A mixture of linseed oil and resin succeeded best with him. He
attached more importance to the thorough penetration of the wood than to
the choice of the penetrating substances. He borrowed his process from
Du Hamel, but to make the necessary suction in the pores he produces a
partial vacuum in the impregnating cylinder by filling it with steam, and
condensing the steam.
Previous to Boucherie’s method, a German, Frantz Moll, in 1835, proposed
to introduce into wood _creosote in a state of vapour_, but the process
was found to be too expensive. This was a modification of Maconochie and
Lukin’s trials in 1805 and 1811.[11] A similar process has since arisen
in New York: we believe Mr. Renwick, of that place, suggested it.
Such were the known labours, when Dr. Boucherie, in December, 1837,
devoted his time to a series of experiments upon timber, with a view to
discover some preservative process which should answer the following
requirements: First, for protecting wood from dry rot or wet rot; second,
for increasing its hardness; third, for preserving and developing its
flexibility and elasticity; fourth, for preventing its decay, and
the fissures that result from it, when, after having been used in
construction, it is left exposed to the variations of the atmosphere;
fifth, for giving it various and enduring colours and odours; and sixth
and last, for greatly reducing its inflammability.
It is a curious coincidence that at Bordeaux, in 1733, the Academy
received a memoir relative to the circulation of the sap and coloured
liquids in plants; and it was at Bordeaux, a century afterwards, viz.
1837, that M. Boucherie first mentioned his method.
M. Boucherie’s process was first discussed in Paris in June, 1840. It
consists in causing a solution of _sulphate of copper_ to penetrate
to the interior of freshly cut woods, to preserve them from decay; he
occasionally used the chloride of calcium, the _pyrolignite of iron_
(_pyrolignite brut de fer_), _prussiate of iron_, _prussiate of copper_,
and various other metallic salts. As a general rule sulphate of copper
is used; but when the hardness of the wood is desired to be increased,
pyrolignite of iron is taken (1 gallon of iron to 6 gallons of water);
and when the object is to render the wood flexible, elastic, and at the
same time uninflammable, chloride of calcium is used. The liquid is taken
up by the tree either whilst growing in the earth or immediately after it
has been felled. Not more than two or three months should be allowed to
elapse before the timber is operated upon, but the sooner it undergoes
the process after being felled the better.
Sulphate of copper is said to be superior to corrosive sublimate. Dr.
Boucherie’s process of the injection of wood with the salts of copper is
as simple as it is easy. For those woods intended for poles it consists
in plunging the base of a branch, furnished with leaves, into a tub
containing the solution. The liquid ascends into the branches by the
action of the leaves, and the wood is impregnated with the preservative
salt. As for logs, the operation consists in cutting down the tree to
be operated upon; fixing at its base a plank, which is fixed by means
of a screw placed in the centre, and which can be tightened at will
when placed in the centre of the tree. This plank has, on the side to
be applied to the bottom of the tree, a rather thick shield of leather,
cloth, pasteboard, or some other substance, intended to establish a space
between it and the wood, sufficient for the preserving fluid to keep in
contact with the freshly cut surface of the tree. The liquid is brought
there from a tub or other reservoir, by the help of a slanting pole made
on the upper surface of the tree, and in which is put a tube, adapted at
its other extremity to a spigot in the upper reservoir which contains
the solution. A pressure of 5 mètres suffices; so that the instant the
sap of the tree is drawn away it escapes, and is replaced by the liquid
saturated with sulphate of copper. The proportion of sulphate of copper
in the solution should be 1 lb. of the salt to 12½ gallons of water. As
soon as the operation terminates (and it lasts for some hours for the
most difficult logs), the wood is ready for use.
For various practical reasons, the first invention of impregnating the
wood of the tree whilst still in a growing state, causing it to suck
up various solutions by means of the absorbing power of the leaves
themselves, was subsequently abandoned; and at the present time a cheap,
simple, and effective process is adopted for impregnating the felled
timbers with the preserving liquid, designated in France “trait de scie,
et la cuisse foulante.” The trunk of a newly felled tree is cut into a
length suitable for two railway sleepers; a cross cut is made on the
prostrate timber to nearly nine-tenths of its diameter; a wedge is then
inserted, and a cord is wound round on the cut surface, leaving a shallow
chamber in the centre, when it is then closed by withdrawing the wedge.
A tube is then inserted through an auger hole into this chamber, and to
this tube is attached an elastic connecting tube from a reservoir placed
some 20 or 30 feet above the level on which the wood lies, and a stream
of the saturating fluid with this pressure passes into the chamber,
presses on the sap in the sap tubes, expels it at each end of the tree,
and itself supplies its place. The fluid used is a solution of copper in
water, in the proportion of 10 or 12 per cent., and a chemical test that
ascertains the pressure of the copper solution is applied at each end of
the tree from which the sap exudes, by which the operator ascertains when
the process is completed.
A full account of this process may be found in the number for June,
1840, of ‘Les Annales de Chimie et de Physique.’ Messrs. de Mirbel,
Arago, Poucelet, Andouin, Gambey, Boussingault, and Dumas, on the part
of l’Académie des Sciences, made a report upon Dr. Boucherie’s process,
confirming the value of the invention. In France, Dr. Boucherie, some
years since, relinquished his brévet, and threw the process open to the
public, in consideration of a national reward; whilst in England he
has obtained two patents (1838 and 1841), which, however, are similar
to Bethell’s patent, obtained by him on July 11, 1838: _which is the
same day and year of Boucherie’s patent_. A prize medal was awarded for
Dr. Boucherie’s process at the Great Exhibition in London, in 1851,
and a grande médaille d’honneur, at the Paris Exhibition of 1855. Many
thousands of railway sleepers have been prepared by this process, and
laid down on the Great Northern Railway of France, and are at present
perfectly sound, whilst others not prepared, on the same line, have
rotted. Boucherie’s process was used on Belgium railways up to 1859; and
it is to be regretted that the reasons which led to its abandonment have
not been given in the reports of the railway administration, as such
reasons would have afforded reliable data for future experimentalists to
go upon.
Messrs. Légé and Fleury-Pironnet’s patent for the injection of sulphate
of copper into beech and poplar is as follows: After the wood is placed,
and the opening hermetically sealed, a jet of steam is introduced,
intended at first to enter the timber and open its pores for the
purpose of obtaining a sudden vacuum, so as to establish at any time a
communication between the interior of the cylinder and the cold water
condenser; at the same time the air pump is put in action. The vacuum
caused is very powerful, and is equal to 25½ ins. of the barometer.
Under the double influence of the heat and the vacuum the sap is quickly
evaporated from the wood as steam, and ejected from the cylinder by the
air pump, so that in a very short time the wood is fully prepared to
admit the preserving liquid through the entire bulk.
The use of sulphate of copper for preserving timber has not been,
however, confined to France, for about the time Dr. Boucherie brought
forward his process, a Mr. Margary took out a patent in England for the
use of the same material. His method consists in steeping the substances
to be preserved in a solution of sulphate of copper, of the strength
of 1 lb. of the sulphate to 8 gallons of water, and leaving them in it
till thoroughly saturated. The timber is allowed to remain in the tank
two days for every inch of its thickness. Another method is to place
the timber in a closed iron vessel of great strength, and it is made to
imbibe the solution by exhaustion and pressure, the operation occupying
but a short time.
Sulphate of copper is sold in quantities at 4_d._ per lb.; so that
100_l._ would buy 6000 lb., and each pound weight is sufficient for 7
or 8 gallons of water, according to Margary; or 12 gallons of water,
according to Boucherie.
To preserve railway sleepers, the French railway engineers require ¼
lb. of sulphate of copper per cubic foot, say at least 12 lbs. to the
load of 50 feet, to be used in a 2 per cent. solution; so that a load
of timber can be rendered imperishable for the sum of four shillings,
exclusive of labour, if sulphate of copper be reckoned at 4_d._ per lb.
With respect to the use of pyrolignite of iron, Mr. Bethell considers it
an expensive process, the pyrolignite costing 6_d._ to 9_d._ per gallon,
whilst the oil of tar can be delivered at from 2_d._ to 3_d._ per gallon:
the cost of these materials is constantly varying.
A great many sleepers were prepared on the Great Western Railway by
pyrolignite of iron, and all have _decayed_. Their black colour makes
them exactly resemble creosoted sleepers, and _many mistakes_ have arisen
from this resemblance.
Messrs. Dorsett and Blythé’s (of Bordeaux) patent process of preparing
wood by the injection of heated solutions of sulphate of copper is
said to have been adopted by French, Spanish, and Italian, as well as
other continental railway companies, by the French Government for their
navy and other constructions, and by telegraph companies for poles
on continental lines. It is as cheap as creosote, and is employed in
places where creosote cannot be had. Wood prepared by it is rendered
incombustible. Wood for outdoor purposes so prepared has a clean
yellowish surface, without odour; it requires no painting, remains
unchangeable for any length of time, and can be employed for any purpose,
the same as unprepared material, and carried with other cargo without
hindrance.[12] Messrs. Dorsett and Blythé’s process is similar to that
of Mr. Knab, which consisted of a solution of sulphate of copper, heated
to nearly boiling point, and placed in a lead cylinder, protected by wood.
In 1846, 80,000 sleepers, treated with sulphate of copper, were laid down
on French railways, and after nine years’ exposure were found to be as
perfect as when first laid.
Mr. H. W. Lewis, University of Michigan, U.S., thus writes in the
‘Journal’ of the Franklin Institute, in 1866, with reference to the decay
of American railway sleepers: “Allowing 2112 sleepers per mile, at 50
cents each, 1056 dols. per mile of American railroad decay every seven
years. Thoroughly impregnate those sleepers with sulphate of copper, at
a cost of 5 cents each, and they would last twice as long. Thus would be
effected a saving of 880 dols. per mile in the seven years on sleepers
alone. In the United States, there are 33,906·6 miles of railroad. The
whole saving on these lines would be 29,389,568 dols., or upwards of
4,262,795 dols. per annum.”
With reference to the decay of unprepared wooden sleepers, it may be here
stated that the renewal of wooden sleepers on the Calcutta and Delhi
Indian line alone costs annually 130,000_l._
The preservative action of sulphate of copper on wood has long been
known, but there are several things in its action which require
explanation. The ‘London Review’ says that Kœnig has lately investigated
the chemical reactions which occur when wood is impregnated with a
preservative solution of blue vitriol. He finds, as a general rule,
that a certain quantity of basic sulphate of copper remains combined
in the pores of the wood in such a manner that it cannot be washed out
with water. The copper salt may be seen by its green colour in the
spaces between the yearly rings in the less compact portions of the
wood, that is to say, in those portions which contain the sap. Those
varieties of wood which contain the most resin retain the largest amount
of the copper salt--oak, for example, retaining but little of it. The
ligneous fibre itself appears to have little or nothing to do with the
fluxation of the copper salt, and indeed none whatever is retained in
chemical combination, so that it cannot be washed out with water, by
pure cellulose. When wood, from which all resin has been extracted by
boiling alcohol, is impregnated with sulphate of copper, it does not
become coloured like the original resinous wood, and the copper salt
contained in it may be readily washed out with water. In like manner,
from impregnated resinous wood all the copper salt may be removed, with
the resin, by means of alcohol. The constituents of the blue vitriol are
consequently fixed in the wood by means of the resin which this contains.
Further, it is found that the impregnated wood contains less nitrogen
than that which is unimpregnated, and that it is even possible to remove
all the nitrogenous components of the wood by long-continued treatment
with the solution of sulphate of copper; the nitrogenous matters being
soluble in an excess of this solution, just as the precipitate which
forms when aqueous solutions of albumen and sulphate of copper are mixed
is soluble in excess of the latter. Since the nitrogenous matters
are well known to be promoters of putrefaction, their removal readily
accounts for the increased durability of the impregnated wood. The
utility of blue vitriol as a preservative may also depend on a measure
upon the resinous copper salt which is formed, by which the pores of the
wood are more or less filled up, and the ligneous fibre covered, so that
contact with the air is prevented, and the attack of insects hindered. It
is suggested that those cases in which the anticipated benefits have not
been realized in practice, by impregnating wood with a solution of blue
vitriol, may probably be referred to the use of an insufficient amount of
this agent; that is, where the wood was not immersed in the solution for
a sufficient length of time. The action should be one of lixiviation, not
merely of absorption.
In 1841, a German, named Müenzing, a chemist of Heibronn, proposed
_chloride of manganese_ (waste liquor in the manufacture of bleaching
powder) as a preservative against dry rot in timber; but his process has
not been adopted in England, and very little noticed abroad.
In July, 1841, Mr. Payne patented his invention for _sulphate of iron_
in London; and in June and November, 1846, in France; and in 1846 in
London, for _carbonate of soda_.[13] The materials employed in Payne’s
process are sulphate of iron and sulphate of lime, both being held in
solution with water. The timber is placed in a cylinder in which a vacuum
is formed by the condensation of steam, assisted by air pumps; a solution
of sulphate of iron is then admitted into the vessel, which instantly
insinuates itself into all the pores of the wood, previously freed from
air by the vacuum, and, after about a minute’s exposure, impregnates
its entire substance; the _sulphate of iron_ is then withdrawn, and
another solution of _sulphate of lime_ thrown in, which enters the
substance of the wood in the same manner as the former solution, and the
two salts react upon each other, and form two new combinations within
the substance of the wood--muriate of iron, and muriate of lime. One
of the most valuable properties of timber thus prepared is its perfect
incombustibility: when exposed to the action of flame or strong heat, it
simply smoulders, and emits no flame. We may also reasonably infer that
with such a compound in its pores, decay must be greatly retarded, and
the liability to worms lessened, if not prevented. The greatest drawback
consists in the increased difficulty of working. This invention has been
approved by the Commissioners of Woods and Forests, and has received
much approbation from the architectural profession. Mr. Hawkshaw, C.E.,
considers that this process renders wood brittle. It was employed for
rendering wood uninflammable in the Houses of Parliament (we presume,
in the carcase; for _steaming_ was used for the joiner’s work), British
Museum, and other public buildings; and also for the Royal Stables at
Claremont.
In 1842, Mr. Bethell stated before the Institute of Civil Engineers,
London, that _silicate of potash_, or _soluble glass_, rendered wood
uninflammable.
In 1842, Professor Brande proposed _corrosive sublimate_ in _turpentine_,
or _oil of tar_, as a preservative solution.
In 1845, Mr. Ransome suggested the application of _silicate of soda_,
to be afterwards decomposed by an acid in the fibre of the wood; and
in 1846, Mr Payne proposed soluble sulphides of the earth (_barium
sulphide_, &c.), to be also afterwards decomposed in the woods by acids.
In 1855, a writer in the ‘Builder’ suggested an equal mixture of alum
and borax (biborate of soda) to be used for making wood uninflammable.
We have no objection to the use of alum and borax to render wood
uninflammable, providing it does not _hurt the wood_.
Such are the _principal_ patents, suggestions, and inventions, up to the
year 1856; but there are many more which have been brought before the
public, some of which we will now describe.
Dr. Darwin, some years since, proposed absorption, first, of _lime
water_, then of a weak solution of _sulphuric acid_, drying between the
two, so as to form a gypsum (sulphate of lime) in the pores of the wood,
the latter to be previously well seasoned, and when prepared to be used
in a dry situation.
Dr. Parry has recommended a preparation composed of _bees-wax_, _roll
brimstone_, and _oil_, in the proportion of 1, 2, and 3 ounces to ¾
gallon of water; to be boiled together and laid on hot.
Mr. Pritchard, C.E., of Shoreham, succeeded in establishing _pyrolignite
of iron_ and _oil of tar_ as a preventive of dry rot; the pyrolignite to
be used very pure, the oil applied afterwards, and to be perfectly free
from any particle of ammonia.
Mr. Toplis recommends the introduction into the pores of the timber of
a solution of sulphate or muriate of iron; the solution may be in the
proportion of about 2 lb. of the salt to 4 or 5 gallons of water.
An invention has been lately patented by Mr. John Cullen, of the North
London Railway, Bow, for preserving wood from decay. The inventor
proposes to use a composition of _coal-tar_, _lime_, and _charcoal_;
the charcoal to be reduced to a fine powder, and also the lime. These
materials to be well mixed, and subjected to heat, and the wood immersed
therein. The impregnation of the wood with the composition may be
materially aided by means of exhaustion and pressure. Wood thus prepared
is considered to be proof against the attacks of the white ant.
The process of preserving wood from decay invented by Mr. L. S. Robins,
of New York, was proposed to be worked extensively by the “British Patent
Wood Preserving Company.” It consists in first removing the surface
moisture, and then charging and saturating the wood with hot _oleaginous
vapours_ and compounds. As the Robins’ process applies the preserving
material in the form of vapour, the wood is left clean, and after a
few hours’ exposure to the air it is said to be fit to be handled for
any purposes in which elegant workmanship is required. Neither science
nor extraordinary skill is required in conducting the process, and the
treatment under the patent is said to involve only a trifling expense.
Reference has already been made to the use of _petroleum_. The almost
unlimited supply of it within the last few years has opened out a new
and almost boundless source of wealth. An invention has been patented
in the name of Mr. A. Prince, which purports to be an improvement in
the mode of preserving timber by the aid of petroleum. The invention
consists, firstly, in the immersion of the timber in a suitable vessel or
receptacle, and to exhaust the air therefrom, by the ordinary means of
preserving wood by saturation. The crude petroleum is next conveyed into
the vessel, and thereby caused to penetrate into every pore or interstice
of the woody fibre, the effect being, it is said, to thoroughly preserve
the wood from decay. He also proposes to mix any cheap mineral paint or
pigment with crude petroleum to be used as a coating for the bottom of
ships before the application of the sheathing, and also to all timber
for building or other purposes. The composition is considered to render
the timber indestructible, and to repel the attacks of insects. Without
expressing any opinion upon this patent as applied to wood for building
purposes, we must again draw attention to the high inflammability of
petroleum.
The ‘Journal’ of the Board of Arts and Manufactures for Upper Canada
considers the following to be the cheapest and the best mode of
preserving timber in Canada: Let the timbers be placed in a drying
chamber for a few hours, where they would be exposed to a temperature of
about 200°, so as to drive out all moisture, and by heat, coagulate the
albuminous substance, which is so productive of decay. Immediately upon
being taken out of the drying chamber, they should be thrown into a tank
containing crude petroleum. As the wood cools, the air in the pores will
contract, and the petroleum occupy the place it filled. Such is the
extraordinary attraction shown by this substance for dry surfaces, that
by the process called capillary attraction, it would gradually find its
way into the interior of the largest pieces of timber, and effectually
coat the walls and cells, and interstitial spaces. During the lapse of
time, the petroleum would absorb oxygen, and become inspissated, and
finally converted into a bituminous substance, which would effectually
shield the wood from destruction by the ordinary processes of decay. The
process commends itself on account of its cheapness. A drying chamber
might easily be constructed of sheet iron properly strengthened, and
petroleum is very abundant and accessible. Immediately after the pieces
of timber have been taken out of the petroleum vat, they should be
sprinkled with wood ashes in order that a coating of this substance may
adhere to the surface, and carbonate of potash be absorbed to a small
depth. The object of this is to render the surface incombustible; and
dusting with wood ashes until quite dry will destroy this property to a
certain extent.
The woodwork of farm buildings in this country is sometimes subjected
to the following: Take two parts of _gas-tar_, one part of _pitch_, one
part _half caustic lime_ and _half common resin_; mix and boil these
well together, and put them on the wood quite hot. Apply two or three
coats, and while the last coat is still warm, dash on it a quantity of
well-washed sharp sand, previously prepared by being sifted through
a sieve. The surface of the wood will then have a complete stone
appearance, and may be durable. It is, of course, necessary, that the
wood be perfectly dry, and one coat should be well hardened before the
next is put on. It is necessary, by the use of lime and long boiling,
to get quit of the ammonia of the tar, as it is considered to injure the
wood.
Mr. Abel, the eminent chemist to the War Department, recommends the
application of _silicate of soda_ in solution, for giving to wood, when
applied to it like paint, a hard coating, which is durable for several
years, and is also a considerable protection against fire. The silicate
of soda, which is prepared for use in the form of a thick syrup, is
diluted in water in the proportion of 1 part by measure of the syrup
to 4 parts of water, which is added slowly, until a perfect mixture is
obtained by constant stirring. The wood is then washed over _two_ or
_three_ times with this liquid by means of an ordinary whitewash brush,
so as to absorb as much of it as possible. When this first coating is
nearly dry, the wood is painted over with _another_ wash made by slaking
good fat lime, diluted to the consistency of thick cream. Then, after the
limewash has become moderately dry, _another_ solution of the silicate
of soda, in the proportion of 1 of soda to 2 of water, is applied in
the same manner as the first coating. The preparation of the wood is
then complete; but if the lime coating has been applied too quickly, the
surface of the wood may be found, when quite dry, after the last coating
of the silicate, to give off a little lime when rubbed with the hand; in
which case it should be _once more_ coated over with a solution of the
silicate of the same strength as in the first operation. If Mr. Abel had
been an architect or builder, he would never have invented this process.
What would the cost be? and would not a special clerk of the works be
necessary to carry out this method in practice?
The following coating for piles and posts, to prevent them from rotting,
has been recommended on account of its being economical, impermeable
to water, and nearly as hard as stone: Take 50 parts of _resin_, 40 of
_finely powdered chalk_, 300 parts of _fine white sharp sand_, 4 parts
of _linseed oil_, 1 part of native _red oxide of copper_, and 1 part
of _sulphuric acid_. First, heat the resin, chalk, sand, and oil, in
an iron boiler; then add the oxide, and, with care, the acid; stir the
composition carefully, and apply the coat while it is still hot. If it be
not liquid enough, add a little more oil. This coating, when it is cold
and dry, forms a varnish which is as hard as stone.
Another method for fencing, gate-posts, garden stakes, and timber which
is to be buried in the earth, may be mentioned. Take 11 lb. of _blue
vitriol_ (sulphate of copper) and 20 quarts of water; dissolve the
vitriol with boiling water, and then add the remainder of the water. The
end of the wood is then to be put into the solution, and left to stand
four or five days; for shingle, three days will answer, and for posts, 6
inches square, ten days, Care should be taken that the saturation takes
place in a well-pitched tank or keyed box, for the reason that any barrel
will be shrunk by the operation so as to leak. Instead of expanding an
old cask, as other liquids do, this shrinks it. This solution has also
been used in dry rot cases, when the wood is only slightly affected.
It will sometimes be found that when oak fencing is put up new, and
tarred or painted, a fungus will vegetate through the dressing, and the
interior of the wood be rapidly destroyed; but when undressed it seems
that the weather desiccates the gum or sap, and leaves only the woody
fibre, and the fence lasts for many years.
About fifteen years ago, Professor Crace Calvert, F.R.S., made an
investigation for the Admiralty, of the qualities of different woods
used in ship-building. He found the goodness of teak to consist in the
fact that it is highly charged with _caoutchouc_; and he considered
that if the tannin be soaked out of a block of oak, it may then be
interpenetrated by a _solution of caoutchouc_, and thereby rendered as
lasting as teak.
We can only spare the space for a few words about this method.
1st. We have seen lead which has formed part of the gutter of a building
previous to its being burnt down: lead melts at 612° F.; caoutchouc at
248° F.; therefore caoutchouc would not prevent wood from being destroyed
by fire. At 248° caoutchouc is highly inflammable, burns with a white
flame and much smoke.
2nd. We are informed by a surgical bandage-maker of high repute, that
caoutchouc, when used in elastic kneecaps, &c., _will perish_, if
the articles are left in a drawer for two or three years. When hard,
caoutchouc is brittle.
Would it be advisable to interpenetrate oak with a solution of
caoutchouc? In 1825, Mr. Hancock proposed a solution of 1½ lb. of
caoutchouc in 3 lb. of essential oil, to which was to be added 9 lb. of
tar. Mr. Parkes, in 1843, and M. Passez, in 1845, proposed to dissolve
caoutchouc in sulphur: painting or immersing the wood. Maconochie, in
1805, after his return from India, proposed distilled _teak_ chips to be
injected into fir woods.
Although England has been active in endeavouring to discover the best
and cheapest remedy for dry rot, France has also been active in the same
direction.
M. le Comte de Chassloup Lambat, Member of the late Imperial Senate of
France, considers that, as _sulphur_ is most prejudicial to all species
of fungi, there might, perhaps, be some means of making it serviceable
in the preservation of timber. We know with what success it is used in
medicine. It is also known that coopers burn a sulphur match in old
casks before using them--a practice which has evidently for its object
the prevention of mustiness, often microscopic, which would impart a bad
flavour to the wine.
M. de Lapparent, late Inspector-General of Timber for the French Navy,
proposed to prevent the growth of fungi by the use of a paint having
flour of sulphur as a basis, and linseed oil as an amalgamater. In 1862
he proposed charring wood; we have referred to this process in our last
chapter (p. 96).
The paint was to be composed of:
Flour of sulphur 200 grammes 3,088 grains.
Common linseed oil 135 ” 2,084 ”
Prepared oil of manganese 30 ” 463 ”
He considered that by smearing here and there either the surfaces of
the ribs of a ship, or below the ceiling, with this paint, a slightly
sulphurous atmosphere will be developed in the hold, which will purify
the air by destroying, at least in part, the sporules of the fungi. He
has since stated that his anticipations have been fully realized. M. de
Lapparent also proposes to prevent the decay of timber by subjecting
it to a skilful carbonization with common inflammable coal gas. An
experiment was made at Cherbourg, which was stated to be completely
successful. The cost is only about 10 cents per square yard of framing
and planking.[14] M. de Lapparent’s gas method is useful for burning
off old paint. We saw it in practice (April, 1875) at Waterloo Railway
Station, London, and it appeared to be effective.
At the suggestion of MM. Le Châtelier (Engineer-in-chief of mines) and
Flachat, C.E.’s, M. Ranee, a few years since, injected in a Légé and
Fleury cylinder certain pieces of white fir, red fir, and pitch pine with
_chloride of sodium_, which had been deprived of the manganesian salts
it contained, to destroy its deliquescent property. Some pieces were
injected four times, but the greatest amount of solution injected into
pitch pine heart-wood was from 3 to 4 per cent., and very little more
was injected into the white and red fir heart-wood. It was also noticed
that sapwood, after being injected four times, only gained 8 per cent.
in weight in the last three operations. The experiments made to test the
relative incombustibility of the injected wood showed that the process
was a complete failure; the prepared wood burning as quickly as the
unprepared wood.
M. Paschal le Gros, of Paris, has patented his system for preserving
all kinds of wood, by means of a _double salt of manganese_ and of
_zinc_, used either alone or with an admixture of _creosote_. The
solution, obtained in either of the two ways, is poured into a trough,
and the immersion of the logs or pieces of wood is effected by placing
them vertically in the trough in such a manner that they are steeped
in the liquid to about three-quarters of their length. The wood is
thus subjected to the action of the solution during a length of time
varying from twelve to forty-eight hours. The solution rises in the
fibres of the wood, and impregnates them by the capillary force alone,
without requiring any mechanical action. The timber is said to become
incombustible, hard, and very lasting.
M. Fontenay, C.E., in 1832, proposed to act upon the wood with what he
designated _metallic soap_, which could be obtained from the residue in
greasing boxes of carriages; also from the acid remains of _oil_, _suet_,
_iron_, and _brass dust_; all being melted together. In 1816 Chapman
tried experiments with _yellow soap_; but to render it sufficiently fluid
it required forty times its weight of water, in which the quantity of
resinous matter and tallow would scarcely exceed ⅟80th; therefore no
greater portion of these substances could be left in the pores of the
wood, which could produce little effect.
M. Letellier, in 1837, proposed to use _deuto-chloride of mercury_ as a
preservative for wood.
M. Dondeine’s process was formerly used in France and Germany. It is a
paint, consisting of many ingredients, the principal being _linseed oil,
resin, white lead, vermilion, lard, and oxide of iron_. All these are to
be well mixed, and reduced by boiling to one-tenth, and then applied
with a brush. If applied cold, a little varnish or turpentine to be added.
Little is known in England of the inventions which have arisen in foreign
countries not already mentioned.
M. Szerelmey, a Hungarian, proposed, in 1868, _potassa_, _lime_,
_sulphuric acid_, _petroleum_, &c., to preserve wood.
In Germany, the following method is sometimes used for the preservation
of wood: Mix 40 parts of _chalk_, 40 parts of _resin_, 4 of _linseed
oil_; melting them together in an iron pot; then add 1 part of native
_oxide of copper_, and afterwards, carefully, 1 part of _sulphuric acid_.
The mixture is applied while hot to the wood by means of a brush, and it
soon becomes very hard.[15]
Mr. Cobley, of Meerholz, Hesse, has patented the following preparation.
A strong solution of _potash_, _baryta_, _lime_, _strontia_, or any of
their salts, are forced into the pores of timber in a close iron vessel
by a pump. After this operation, the liquid is run off from the timber,
and _hydro-fluo-silicic acid_ is forced in, which, uniting with the salts
in the timber, forms an insoluble compound capable of rendering the wood
uninflammable.
About the year 1800, Neils Nystrom, chemist, Norkopping, recommended
a solution of _sea salt and copperas_, to be laid upon timber as hot
as possible, to prevent rottenness or combustion. He also proposed a
solution of _sulphate of iron_, _potash_, _alum_, &c., to extinguish
fires.
M. Louis Vernet, Buenos Ayres, proposed to preserve timber from fire by
the use of the following mixture: Take 1 lb. of _arsenic_, 6 lb. of
_alum_, and 10 lb. of _potash_, in 40 gallons of water, and mix with
_oil_, or any suitable tarry matters, and paint the timber with the
solution. We have already referred to the conflicting evidence respecting
alum and water for wood: we can now state that Chapman’s experiments
proved that _arsenic_ afforded no protection against dry rot. Experiments
in Cornwall have proved that where arsenical ores have lain on the
ground, vegetation will ensue in two or three years after removal of the
ore. If, therefore, alum or arsenic have no good effect on timber with
respect to the dry rot, we think the use of both of them together would
certainly be objectionable.
The last we intend referring to is a composition frequently used in
China, for preserving wood. Many buildings in the capital are painted
with it. It is called _Schoicao_, and is made with 3 parts of blood
deprived of its febrine, 4 parts of lime and a little alum, and 2 parts
of liquid silicate of soda. It is sometimes used in Japan.
It would be practically useless to quote any further remedies, and the
reader is recommended to carefully study those quoted in this chapter,
and of their utility to judge for himself, bearing in mind those
principles which we have referred to before commencing to describe the
patent processes. A large number of patents have been taken out in
England for the preservation of wood by preservative processes, but
only two are now in use,--that is, to any extent,--viz. Bethell’s and
Burnett’s. Messrs. Bethell and Co. now impregnate timber with _copper,
zinc, corrosive sublimate, or creosote_; the four best patents.
We insert here a short analysis of different _methods_ proposed for
seasoning timber:--
Vacuum and Pressure Processes generally.
Bréant’s.
Bethell’s.
Payne’s.
Perin’s.
Tissier’s.
Vacuum by Condensation of Steam.
Tissier.
Bréant.
Payne.
Renard Perin, 1848.
Brochard and Watteau, 1847.
Separate Condenser.
Tissier.
Employ Sulphate of Copper in closed vessels.
Bethell’s Patent, 11th July, 1838.
Tissier, 22nd October, 1844.
Molin’s Paper, 1853.
Payen’s Pamphlet.
Légé and Fleury’s Pamphlet.
Current of Steam.
Moll’s Patent, 19th January, 1835.
Tissier’s ” 22nd October, 1844.
Payne’s ” 14th Nov., 1846.
Meyer d’Uslaw, 2nd January, 1851.
Payen’s Pamphlet.
Hot Solution.
Tissier’s Patent, 22nd October, 1844.
Knab’s Patent, 8th September, 1846.
Most solutions used are heated.
The following are the chief _ingredients_ which have been recommended,
and some of them tried, to prevent the decomposition of timber, and the
growth of fungi:--
Acid, Sulphuric.
” Vitriolic.
” of Tar.
Carbonate of Potash.
” Soda.
” Barytes.
Sulphate of Copper.
” Iron.
” Zinc.
” Lime.
” Magnesia.
” Barytes.
” Alumina.
” Soda.
Salt, Neutral.
Salt, Selenites.
Oil, Vegetable.
” Animal.
” Mineral.
Muriate of Soda.
Marcosites, Mundic.
” Barytes.
Nitrate of Potash.
Animal Glue.
” Wax.
Quick Lime.
Resins of different kinds.
Sublimate, Corrosive.
Peat Moss.
For the _non-professional_ reader we find we have _three_ facts:
1st. The most successful patentees have been Bethell and Burnett, in
England; and Boucherie, in France: all B’s.
2nd. The most successful patents have been _knighted_. Payne’s patent
was, we believe, used by Sirs R. Smirke and C. Barry; Kyan’s, by Sir
R. Smirke; Burnett’s, by Sirs M. Peto, P. Roney, and H. Dryden; while
Bethell’s patent can claim Sir I. Brunel, and many other knights. We
believe Dr. Boucherie received the Legion of Honour in France.
3rd. There are only at the present time three timber-preserving works in
London, and they are owned by Messrs. Bethell and Co., Sir F. Burnett and
Co., and Messrs. Burt, Boulton, and Co.: all names commencing with the
letter B.
For the _professional_ reader we find we have _three hard_ facts:
The most successful patents may be placed in three classes, and we give
the key-note of their success.
1st. ONE MATERIAL AND ONE APPLICATION.--Creosote, Petroleum.
_Order_--Ancient Egyptians, or Bethell’s, Burmese.
2nd. TWO MATERIALS AND ONE APPLICATION.--Chloride of zinc and
water; sulphate of copper and water; corrosive sublimate and water.
_Order_--Burnett, Boucherie, Kyan.
3rd. TWO MATERIALS AND TWO APPLICATIONS.--Sulphate of iron and water;
afterwards sulphate of lime and water. Payne.
We thus observe there are _twice three_ successful patent processes.
Any inventions which cannot be brought under these three classes have had
a short life; at least, we think so.
The same remarks will apply to _external_ applications for wood--for
instance, coal-tar, _one application_, is more used for fencing than any
other material.
We are much in want of a valuable series of experiments on the
application of various chemicals on wood to resist _burning to pieces_;
without causing it to _rot speedily_.
CHAPTER VI.
ON THE MEANS OF PREVENTING DRY ROT IN MODERN HOUSES; AND THE CAUSES OF
THEIR DECAY.
Although writers on dry rot have generally deemed it a new disease, there
is foundation to believe that it pervaded the British Navy in the reign
of Charles II. “Dry rot received a little attention” so writes Sir John
Barrow, “about the middle of the last century, at some period of Sir John
Pringle’s presidency of the Royal Society of London.” As timber trees
were, no doubt, subject to the same laws and conditions 500 years ago as
they are at the present day, it is indeed extremely probable that if at
that time unseasoned timber was used, and subjected to heat and moisture,
dry rot made its appearance. We propose in this chapter to direct
attention to the several causes of the decay of wood, which by proper
building might be averted.
The necessity of proper ventilation round the timbers of a building has
been repeatedly advised in this volume; for even timber which has been
naturally seasoned is at all times disposed to resume, from a warm and
stagnant atmosphere, the elements of decay. We cannot therefore agree
with the following passage from Captain E. M. Shaw’s book on ‘Fire
Surveys,’ which is to be found at page 44:--“Circulation of air should
on no account be permitted in any part of a building not exposed to
view, especially under floors, or inside skirting boards, or wainscots.”
In the course of this chapter, the evil results from a want of a proper
circulation of air will be shown.
In warm cellars, or any close confined situations, where the air is
filled with vapour without a current to change it, dry rot proceeds
with astonishing rapidity, and the timber work is destroyed in a very
short time. The bread rooms of ships; behind the skirtings, and under
the wooden floors, or the basement stories of houses, particularly in
kitchens, or other rooms where there are constant fires; and, in general,
in every place where wood is exposed to warmth and damp air, the dry rot
will soon make its appearance.
All kinds of stoves are sure to increase the disease if moisture be
present. The effect of heat is also evident from the rapid decay of ships
in hot climates; and the warm moisture given out by particular cargoes
is also very destructive. Hemp will, without being injuriously heated,
emit a moist warm vapour: so will pepper (which will affect teak) and
cotton. The ship ‘Brothers’ built at Whitby, of green timber, proceeded
to St. Petersburgh for a cargo of hemp. The next year it was found on
examination that her timbers were rotten, and all the planking, except a
thin external skin. It is also an important fact that rats very rarely
make their appearance in dry places: under floors they are sometimes very
destructive.
As rats will sometimes destroy the structural parts of wood framing,
a few words about them may not be out of place. If poisoned wheat,
arsenic, &c., be used, the creatures will simply eat the things and
die under the floor, causing an intolerable stench. The best method
is to make a small hole in a corner of the floor (unless they make it
themselves) large enough to permit them to come up; the following course
is then recommended:--Take oil of amber and ox-gall in equal parts; add
to them oatmeal or flour sufficient to form a paste, which divide into
little balls, and lay them in the middle of the infested apartment _at
night_ time. Surround the balls with a number of saucers filled with
water--the smell of the oil is sure to attract the rats, they will
greedily devour the balls, and becoming intolerably thirsty will drink
till they die on the spot. They can be buried in the morning.
Building timber into new walls is often a cause of decay, as the lime and
damp brickwork are active agents in producing putrefaction, particularly
where the scrapings of roads are used, instead of sand, for mortar. Hence
it is that bond timbers, wall plates, and the ends of girders, joists,
and lintels are so frequently found in a state of decay. The ends of
brestsummers are sometimes cased in sheet lead, zinc, or fire-brick, as
being impervious to moisture. The old builders used to bed the ends of
girders and joists in loam instead of mortar, as directed in the Act of
Parliament, 19 Car. II. c. 3, for rebuilding the City of London.
In Norway, all posts in contact with the earth are carefully wrapped
round with flakes of birch bark for a few inches above and below the
ground.
Timber that is to lie in mortar--as, for instance, the ends of joists,
door sills and frames of doors and windows, and the ends of girders--if
pargeted over with hot pitch, will, it is said, be preserved from the
effects of the lime. In taking down, some years since, in France, some
portion of the ancient Château of the Roque d’Oudres, it was found that
the extremities of the oak girders were perfectly preserved, although
these timbers were supposed to have been in their places for upwards
of 600 years. The whole of these extremities buried in the walls were
completely wrapped round with plates of cork. When demolishing an
ancient Benedictine church at Bayonne, it was found that the whole of
the fir girders were entirely worm eaten and rotten, with the exception,
however, of the bearings, which, as in the case just mentioned, were
also completely wrapped round with plates of cork. These facts deserve
consideration.
If any of our professional readers should wish to try cork for the ends
of girders, they will do well to choose the Spanish cork, which is the
best.
In this place it may not be amiss to point out the dangerous consequences
of building walls so that their principal support depends on timber. The
usual method of putting bond timber into walls is to lay it next the
inside; this bond often decays, and, of course, leaves the walls resting
only upon the external course or courses of brick; and fractures, bulges,
or absolute failures are the natural consequences. This evil is in some
degree avoided by placing the bond in the middle of the wall, so that
there is brickwork on each side, and by not putting continued bond for
nailing the battens to. We object to placing bond in the middle of a
wall: the best way, where it can be managed, is to corbel out the wall,
resting the ends of the joists on the top course of bricks; thus doing
away with the wood-plate. In London, wood bond is prohibited by Act of
Parliament, and hoop-iron bond (well tarred and sanded) is now generally
used. The following is an instance of the bad effects of placing wood
bond in walls: In taking down portions of the audience part and the
whole of the corridors of the original main walls of Covent Garden
Theatre, London, in 1847, which had only been built about thirty-five
years, the wood horizontal bond timbers, although externally appearing
in good condition, were found, on a close examination by Mr. Albano,
much affected by shrinkage, and the majority of them quite rotten in the
centre, consequently the whole of them were ordered to be taken out in
short lengths, and the space to be filled in with brickwork and cement.
Some years since we had a great deal to do with “Fire Surveys;” that is
to say, surveying buildings to estimate the cost of reinstating them
after being destroyed by fire; and we often noticed that the wood bond,
being rotten, was seriously charred by the fire, and had to be cut out
in short lengths, and brickwork in cement “pinned in” in its place.
Brestsummers and story posts are rarely sufficiently burnt to affect the
stability of the front wall of a shop building.
In bad foundations, it used to be common, before concrete came into
vogue, to lie planks to build upon. Unless these planks were absolutely
wet, they were certain to rot in such situations, and the walls settled;
and most likely irregularly, rending the building to pieces. Instances
of such kind of failure frequently occur. It was found necessary, a few
years since, to underpin three of the large houses in Grosvenor Place,
London, at an immense expense. In one of these houses the floors were not
less than three inches out of level, the planking had been seven inches
thick, and most of it was completely rotten: it was of yellow fir. A like
accident happened to Norfolk House, St. James’s Square, London, where oak
planking had been used.
As an example of the danger of trusting to timber in supporting heavy
stone or brickwork, the failure of the curb of the brick dome of the
church of St. Mark, at Venice, may be cited. This dome was built upon
a curb of larch timber, put together in thicknesses, with the joints
crossed, and was intended to resist the tendency which a dome has to
spread outwards at the base. In 1729, a large crack and several smaller
ones were observed in the dome. On examination, the wooden curb was
found to be in a completely rotten state, and it was necessary to raise
a scaffold from the bottom to secure the dome from ruin. After it was
secured from falling, the wooden curb was removed, and a course of stone,
with a strong band of iron, was put in its place.
It is said that another and very important source of destruction is the
applying end to end of two different kinds of wood: oak to fir, oak to
teak or lignum vitæ; the harder of the two will decay at the point of
juncture.
The bad effects resulting from damp walls are still further increased by
hasty finishing. To enclose with plastering and joiners’ work the walls
and timbers of a building while they are in a damp state is the most
certain means of causing the building to fall into a premature state of
decay.
Mr. George Baker, builder of the National Gallery, London, remarked, in
1835, “I have seen the dry rot all over Baltic timber in three years, in
consequence of putting it in contact with moist brickwork; the rot was
caused by the badness of the mortar, it was so long drying.”
Slating the external surface of a wall, to keep out the rain or damp,
is sometimes adopted: a high wall (nearly facing the south-west) of a
house near the north-west corner of Blackfriars Bridge, London, has been
recently slated from top to bottom, to keep out damp.
However well timber may be seasoned, if it be employed in a damp
situation, decay is the certain consequence; therefore it is most
desirable that the neighbourhood of buildings should be well drained,
which would not only prevent rot, but also increase materially the
comfort of those who reside in them. The drains should be made
water-tight wherever they come near to the walls; as walls, particularly
brick walls, draw up moisture to a very considerable height: very strict
supervision should be placed over workmen while the drains of a building
are being laid. Earth should never be suffered to rest against walls,
and the sunk stories of buildings should always be surrounded by an open
area, so that the walls may not absorb moisture from the earth: even open
areas require to be properly built. We will quote a case to explain our
meaning. A house was erected about eighteen months ago, in the south-east
part of London, on sloping ground. Excavations were made for the basement
floor, and a dry area, “brick thick, in cement,” was built at the back
and side of the house, the top of the area wall being covered with a
stone coping; we do not know whether the bottom of the area was drained.
On the top of the coping was placed mould, forming one of the garden beds
for flowers. Where the mould rested against the walls, damp entered. The
area walls should have been built, in the first instance, above the level
of the garden-ground--which has since been done--otherwise, in course of
time, the ends of the next floor joists would have become attacked by dry
rot.
Some people imagine that if damp is in a wall the best way to get rid of
it is to seal it in, by plastering the inside and stuccoing the outside
of the wall; this is a great mistake; damp will rise higher and higher,
until it finds an outlet; rotting in the meanwhile the wood bond and
ends of all the joists. We were asked recently to advise in a curious
case of this kind at a house in Croydon. On wet days the wall (_stucco_,
outside; _plaster_, inside) was perfectly wet: bands of soft red bricks
in wall, at intervals, were the culprits. To prevent moisture rising from
the foundations, some substance that will not allow it to pass should be
used at a course or two above the footings of the walls, but it should
be below the level of the lowest joists. “Taylor’s damp course” bricks
are good, providing the air-passages in them are kept free for air to
pass through: they are allowed sometimes to get choked up with dirt.
Sheets of lead or copper have been used for that purpose, but they are
very expensive. Asphalted felt is quite as good; no damp can pass through
it. Care must, however, be taken in using it if only one wall, say a
party wall, has to be built. To lay two or three courses of slates,
bedded in cement, is a good method, providing the slates “break joint,”
and are well bedded in the cement. Workmen require watching while this
is being done, because if any opening be left for damp to rise, it will
undoubtedly do so. A better method is to build brickwork a few courses in
height with Portland cement instead of common mortar, and upon the upper
course to lay a bed of cement of about one inch in thickness; or a layer
of asphalte (providing the walls are all carried up to the same level
before the asphalte is applied hot). As moisture does not penetrate these
substances, they are excellent materials for keeping out wet; and it can
easily be seen if the mineral asphalte has been properly applied. To keep
out the damp from basement floors, lay down cement concrete 6 inches
thick, and on the top, asphalte 1 inch thick, and then lay the sleepers
and joists above; or bed the floor boards on the asphalte.
The walls and principal timbers of a building should always be left for
some time to dry after it is covered in. This drying is of the greatest
benefit to the work, particularly the drying of the walls; and it also
allows time for the timbers to get settled to their proper bearings,
which prevents after-settlements and cracks in the finished plastering.
It is sometimes said that it is useful because it allows the timber more
time to season; but when the carpenter considers that it is from the
ends of the timber that much of its moisture evaporates, he will see
the impropriety of leaving it to season after it is framed, and also
the cause of framed timbers of unseasoned wood failing at the joints
sooner than in any other place. No parts of timber require the perfect
extraction of the sap so much as those that are to be joined.
When the plastering is finished, a considerable time should be allowed
for the work to get dry again before the skirtings, the floors, and
other joiners’ work be fixed. Drying will be much accelerated by a free
admission of air, particularly in favourable weather. When a building
is thoroughly dried at first, openings for the admission of fresh air
are not necessary _when the precautions against any new accessions of
moisture have been effectual_. Indeed, such openings only afford harbour
for vermin: unfortunately, however, buildings are so rarely dried when
first built, that air-bricks, &c., in the floors are very necessary, and
if the timbers were so dried as to be free from water (which could be
done by an artificial process), the wood would only be fit for joinery
purposes. Few of our readers would imagine that water forms ⅕th part of
wood. Here is a table (compiled from ‘Box on Heat,’ and Péclet’s great
work ‘Traité de la Chaleur’):--
WOOD.
Elements. Ordinary state.
Carbon ·408
Hydrogen ·042
Oxygen ·334
_Water_ _·200_
Ashes ·016
-----
1·000
Many houses at our seaport towns are erected with mortar, having
sea-sand in its composition, and then dry rot makes its appearance. If
no other sand can be obtained, the best way is to have it washed at
least _three times_ (the contractor being under strict supervision, and
subject to heavy penalties for evasion). After each washing it should be
left exposed to the action of the sun, wind, and rain: the sand should
also be frequently turned over, so that the whole of it may in turn
be exposed; even then it tastes saltish, after the third operation. A
friend of ours has a house at Worthing, which was erected a few years
since with sea-sand mortar, and on a wet day there is always a dampness
hanging about the house--every third year the staircase walls have to be
repapered: it “bags” from the walls.
In floors next the ground we cannot easily prevent the access of damp,
but this should be guarded against as far as possible. All mould should
be carefully removed, and, if the situation admits of it, a considerable
thickness of dry materials, such as brickbats, dry ashes, broken glass,
clean pebbles, concrete, or the refuse of vitriol-works; but no lime
(unless unslaked) should be laid under the floor, and over these a
coat of smiths’ ashes, or of pyrites, where they can be procured. The
timber for the joists should be well seasoned; and it is advisable to
cut off all connection between wooden ground floors and the rest of the
woodwork of the building. A flue carried up in the wall next the kitchen
chimney, commencing under the floor, and terminating at the top of the
wall, and covered to prevent the rain entering, would take away the damp
under a kitchen floor. In Hamburg it is a common practice to apply
mineral asphalte to the basement floors of houses to prevent capillary
attraction; and in the towns of the north of France, gas-tar has become
of very general use to protect the basement of the houses from the
effects of the external damp.
Many houses in the suburbs (particularly STUCCONIA) of London are erected
by speculating builders. As soon as the carcase of a house is finished
(perhaps before) the builder is unable to proceed, for want of money,
and the carcase is allowed to stand unfinished for months. Showers of
rain saturate the previously unseasoned timbers, and pools of water
collect on the basement ground, into which they gradually, but surely,
soak. Eventually the houses are finished (probably by half a dozen
different tradesmen, employed by a mortgagee); bits of wood, rotten
sawdust, shavings, &c., being left under the basement floor. The house
when finished, having pretty (!) paper on the walls, plate-glass in the
window-sashes, and a bran new brick and stucco portico to the front door,
is quickly let. Dry rot soon appears, accompanied with its companions,
the many-coloured fungi; and when their presence should be known from
their smell, the anxious wife probably exclaims to her husband, “My dear!
there is a very strange smell which appears to come from the children’s
playroom: had you not better send for Mr. Wideawake, the builder, for
I am sure there is _something the matter with the drains_.” Defective
ventilation, dry rot, _green_ water thrown down sinks, &c., do not cause
smells, it’s _the drains_, of course!
There is another cause which affects all wood most materially, which
is the application of paint, tar, or pitch before the wood has been
thoroughly dried. The nature of these bodies prevents all evaporation;
and the result of this is that the centre of the wood is transformed into
touchwood. On the other hand, the doors, pews, and carved work of many
old churches have never been painted, and yet they are often found to be
perfectly sound, after having existed more than a century. In Chester,
Exeter, and other old cities, where much timber was formerly used, even
for the external parts of buildings, it appears to be sound and perfect,
though black with age, and has never been painted.
Mr. Semple, in his treatise on ‘Building in Water,’ mentions an instance
of some field-gates made of home fir, part of which, being near the
mansion, were painted; while the rest, being in distant parts of the
grounds, were not painted. Those which were painted soon became quite
rotten, but the others, which were not painted, continued sound.
Another cause of dry rot, which is sometimes found in suburban and
country houses, is the presence of large trees near the house. We are
acquainted with the following remarkable instance:--At the northern end
of Kilburn, London, stands Stanmore Cottage, erected a great many years
ago: about fifty feet in front of it is an old elm-tree. The owner, a few
years since, noticed cracks round the portico of the house; these cracks
gradually increased in size, and other cracks appeared in the window
arches, and in different parts of the external and internal walls. The
owner became alarmed, and sent for an experienced builder, who advised
underpinning the walls. Workmen immediately commenced to remove the
ground from the foundations, and it was then found that the foundations,
as well as the joists, were honeycombed by the roots of the elm-tree,
which were growing alongside the joists, the whole being surrounded by
large masses of white and yellow dry-rot fungus.
The insufficient use of tarpaulins is another frequent cause of dry rot.
A London architect had (a few years since) to superintend the erection
of a church in the south-west part of London; an experienced builder was
employed. The materials were of the best description and quality. When
the walls were sufficiently advanced to receive the roof, rain set in; as
the clown in one of Shakespeare’s plays observed, “the rain, it raineth
every day;” it was so, we are told, in this case for some days. The roof
when finished was ceiled below with a plaster ceiling; and above (not
with “dry oakum without pitch” but) with slates. A few months afterwards
some of the slates had to be reinstated, in consequence of a heavy storm,
and it was then discovered that nearly all the timbers of the roof were
affected by dry rot. This was an air-tight roof.
In situations favourable to rot, painting prevents every degree of
exhalation, depriving at the same time the wood of the influence of the
air, and the moisture runs through it, and insidiously destroys the wood.
Most surveyors know that moist oak cills to window frames will soon rot,
and the painting is frequently renewed; a few taps with a two-feet
brass rule joint on the top and front of cill will soon prove their
condition. Wood should be a year or more before it is painted; or, better
still, never painted at all. Artificers can tell by the sound of any
substance whether it be healthy or decayed as accurately as a musician
can distinguish his notes: thus, a bricklayer strikes the wall with his
crow, and a carpenter a piece of timber with his hammer. The Austrians
used formerly to try the goodness of the timber for ship-building by the
following method: One person applies his ear to the centre of one end of
the timber, while another, with a key, hits the other end with a gentle
stroke. If the wood be sound and good, the stroke will be distinctly
heard at the other end, though the timber should be fifty feet or more in
length. Timber affected with rot yields a particular sound when struck,
but if it were painted, and the distemper had made much progress, with
no severe stroke the outside breaks like a shell. The auger is a very
useful instrument for testing wood; the wood or sawdust it brings out can
be judged by its smell; which may be the fresh smell of pure wood: the
vinous smell, or first degree of fermentation, which is alcoholic; or the
second degree, which is putrid. The sawdust may also be tested by rubbing
it between the fingers.
According to Colonel Berrien, the Michigan Central Railroad Bridge, at
Niles, was painted _before seasoning_, with “Ohio fire-proof paint,”
forming a glazed surface. After five years it was so rotten as to require
rebuilding.
Painted floor-cloths are very injurious to wooden floors, and frequently
produce rottenness in the floors that are covered with them, as the
painted cloth prevents the access of air, and retains whatever dampness
the boards may absorb, and therefore soon causes decay. Carpets are not
so injurious, but still assist in retarding free evaporation.
Captain E. M. Shaw, in ‘Fire Surveys,’ thus writes of the floors of a
building, “They might with advantage be caulked like a ship’s deck, only
with dry oakum, without pitch.” Let us see how far oil floor-cloth and
kamptulicon will assist us in obtaining an air-tight floor.
In London houses there is generally _one_ room on the basement floor
which is carefully covered over with an oiled floor-cloth. In such a room
the dry rot often makes its appearance. The wood absorbs the aqueous
vapour which the oil-cloth will not allow to escape; and being assisted
by the heat of the air in such apartments, the decay goes on rapidly.
Sometimes, however, the dry rot is only confined to the top of the floor.
At No. 106, Fenchurch Street, London, a wood floor was washed (a few
years since) for a tenant, and oil-cloth was laid down. Circumstances
necessitated his removal a few months afterwards; and it was then found
that the oil-cloth had grown, so to speak, to the wood flooring, and had
to be taken off with a chisel: the dry rot had been engendered merely on
the surface of the floor boards, as they were sound below as well as the
joists: air bricks were in the front wall.
We have seen many instances of dry rot in _passages_, where oiled
floor-cloth has been nailed down and not been disturbed for two or three
years.
In ordinary houses, where floor-cloth is laid down in the _front_
kitchen, no ventilation under the floors, and a fire burning every day
in the stove, dry rot often appears. In the _back_ kitchen, where there
is no floor-cloth, and only an occasional fire, it rarely appears. The
air is warm and stagnant under one floor, and cold and stagnant under the
other: at the temperature of 32° to 40° the progress of dry rot is very
slow.
And how does _kamptulicon_ behave itself? The following instances of
the rapid progress of dry rot from external circumstances have recently
been communicated to us; they show that, under favourable circumstances
as to choice of timber and seasoning, this fungus growth can be readily
produced by _casing-in_ the timber with substances impervious, or nearly
so, to air.
At No. 29, Mincing Lane, London, in _two_ out of three rooms on the
_first_ floor, upon a fire-proof floor constructed on the Fox and Barrett
principle (of iron joists and concrete with yellow pine sleepers, on
strips of wood bedded in cement, to which were nailed the yellow pine
floor-boards) kamptulicon was nailed down by the tenant’s orders. In less
than nine months the whole of the wood sleepers, and strips of wood, as
well as the boards, were seriously injured by dry rot; whilst the third
room floor, which had been covered with a carpet, was perfectly sound.
At No. 79, Gracechurch Street, London, a room on the second floor was
inhabited, as soon as finished, by a tenant who had kamptulicon laid
down. This floor was formed in the ordinary way, with the usual sound
boarding of strips of wood, and concrete two inches thick filled in on
the same, leaving a space of about two inches under the floor boards. The
floor was seriously decayed by dry rot in a few months down to the level
of the concrete pugging, below which it remained sound, and could be
pulled up with the hand.
We will now leave oil-cloth and kamptulicon, and try what “Keene’s
cement” will do for an “air-tight” partition of a house.
At No. 16, Mark Lane, London, a partition was constructed of sound yellow
deal quarters, covered externally with “Keene’s cement, on lath, both
sides.” It was removed about two years after its construction, when it
was found that the timber was completely _perished from dry rot_; so much
so, that the timbers parted in the middle in places, and were for some
time afterwards moist.
It is still unfortunately the custom to keep up the old absurd fashion of
disguising woods, instead of revealing their natural beauties. Instead
of wasting time in perfect imitations of scarce or dear woods, it would
be much better to employ the same amount of time in fully developing the
natural characteristics of many of our native woods, now destined for
decorative purposes because they are cheap and common; although many
of our very commonest woods are very beautifully grained, but their
excellences for ornamentation are lost because our decorators have not
studied the best mode of developing their beauties. Who would wish that
stained deal should be painted in imitation of oak? or that the other
materials of a less costly and inferior order should have been painted
over instead of their natural faces being exposed to view? There are
beauties in all the materials used. The inferior serve to set off by
comparison the more costly, and increase their effect. The red, yellow,
and white veins of the pine timber are beautiful: the shavings are like
silk ribbons, which only nature could vein after that fashion, and to
imitate which would puzzle all the _tapissiers_ of the Rue Mouffetard, in
Paris.
Why should not light and dark woods be commonly used in combination
with each other in our joinery? Wood may be stained of various shades,
from light to dark. The dirt or dust does not show more on stained wood
than it does on paint, and can be as easily cleaned and refreshed by
periodical coats of varnish. Those parts subjected to constant wear and
tear can be protected by more durable materials, such as finger-plates,
&c. Oak can be stained dark, almost black, by means of bichromate
of potash diluted with water. Wash the wood over with a solution of
gallic acid of any required strength, and allow it to thoroughly dry.
To complete the process, wash with a solution of iron in the form
of “tincture of steel,” or a decoction of vinegar and iron filings,
and a deep and good stain will be the result. If a positive black is
required, wash the wood over with gallic acid and water two or three
times, allowing it to dry between every coat; the staining with the iron
solution may be repeated. Raw linseed oil will stay the darker process at
any stage.
Doors made up of light deal, and varied in the staining, would look as
well as the ordinary graining. Good and well-seasoned materials would
have to be used, and the joiners’ work well fitted and constructed.
Mouldings of a superior character, and in some cases gilt, might be used
in the panels, &c. For doors, plain oak should be used for the stiles
and rails, and pollard oak for the panels. If rose-wood or satin-wood be
used, the straight-grained wood is the best adapted for stiles and rails;
and for mahogany doors, the lights and shades in the panels should be
stronger than in the stiles and rails.
Dark and durable woods might be used in parts most exposed to wear and
tear.
Treads of stairs might be framed with oak nosings, if not at first, at
least when necessary to repair the nosings.
Skirtings could be varied by using dark and hard woods for the lower part
or plinth, lighter wood above, and finished with superior mouldings. It
must, however, be remembered that, contrary to the rule that holds good
with regard to most substances, the colours of the generality of woods
become considerably _darker_ by exposure to the light; allowance would
therefore have to be made for this. All the woodwork _must_, previously
to being fixed, be well seasoned.
The practice here recommended would be more expensive than the common
method of painting, but in many cases it would be better than graining,
and cheaper in the long run. Oak wainscot and Honduras mahogany doors are
twice the price of deal doors; Spanish mahogany three times the price.
When we consider that by using the natural woods, French polished, we
save the cost of four coats of paint and graining (the customary modes),
the difference in price is very small. An extra 50_l._ laid out on a
500_l._ house would give some rooms varnished and rubbed fittings,
without paint. Would it not be worth the outlay? It may be said that
spots of grease and stains would soon disfigure the bare wood; if so,
they could easily be removed by the following process: Take a quarter of
a pound of fuller’s earth, and a quarter of a pound of pearlash, and boil
them in a quart of soft water, and, while hot, lay the composition on the
greased parts, allowing it to remain on them for ten or twelve hours;
after which it may be washed off with fine sand and water. If a floor be
much spotted with grease, it should be completely washed over with this
mixture, and allowed to remain for twenty-four hours before it is removed.
Let us consider how we paint our doors, cupboards, &c., at the present
time. For our best houses, the stiles of our doors are painted French
white; and the panels, pink, or salmon colour! For cheaper houses, the
doors, cupboards, window linings, &c., are generally two shades of what
is called “stone colour” (as if stone was always the same colour), and
badly executed into the bargain: the best rooms having the woodwork
grained in imitation of oak, or satin-wood, &c. And such imitations!
Mahogany and oak are now even imitated on leather and paper-hangings.
Wood, well and cleanly varnished, stained, or, better still, French
polished, must surely look better than these daubs. But French polish is
not extensively used in England: it is confined to cabinet pieces and
furniture, except in the houses of the aristocracy. Clean, colourless
varnish ought to be more generally used to finish off our woodwork,
instead of the painting now so common. The varnish should be clean and
colourless, as the yellow colour of the ordinary varnishes greatly
interferes with the tints of the light woods.
In the Imperial Palace, at Berlin, one or two of the Emperor’s private
rooms are entirely fitted up with deal fittings; doors, windows,
shutters, and everything else of fir-wood. “Common deal,” if well
selected, is beautiful, cheap, and pleasing.
We have seen the offices of Herr Krauss (architect to Prince and Princess
Louis of Hesse), who resides at Mayence, and they are fitted up, or
rather the walls and ceilings are lined, with picked pitch pine-wood,
parts being carved, and the whole French polished, and the effect is much
superior to any paint, be it “stone colour,” “salmon colour,” or even
“French white.”
The reception-room, where the Emperor of Germany usually transacts
business with his ministers, and receives deputations, &c., as well as
the adjoining cabinets, are fitted with deal, not grained and painted,
but well French polished. The wood is, of course, carefully selected,
carefully wrought, and excellently French polished, which is the great
secret of the business. In France, it is a very common practice to polish
and wax floors.
The late Sir Anthony Carlisle had the interior woodwork of his house,
in Langham Place, London, varnished throughout, and the effect of the
varnished deal was very like satin-wood.
About forty years since, Mr. J. G. Crace, when engaged on the decoration
of the Duke of Hamilton’s house, in the Isle of Arran, found the woodwork
of red pine so free from knots, and so well executed, that instead of
painting it, he had it only varnished. It was a great success, and ten
years after looked nearly as well as when first done.
The late Mr. Owen Jones, whose works on colour decoration are well known,
was employed a few years since by Mr. Alfred Morrisson to decorate his
town and country houses. At the country house (Fonthill House), Mr.
Jones built a room for the display of Chinese egg-shell pottery, the
chimneypiece and fittings being entirely of ebony, inlaid with ivory, and
the ceiling of wood, panelled and inlaid, the mouldings being black and
gold. At the town house, in Carlton House Terrace, London, the woodwork
of the panelling, dadoes, doors, architraves, window-shutters, and all
the rooms on the ground and first floors is inlaid, from designs by Mr.
Jones, with various woods of different kinds, the colours of which were
carefully selected by him, with a view to perfect harmony of colouring.
A house has recently been erected (from the designs of Mr. J. W.
McLaughlin, architect) near Cincinnati, Ohio, United States, which is
a perfect model with regard to the amount of woodwork used. The walls
of the _hall_ are finished with walnut wainscoting; the fireplace is
an open one, with a walnut mantelpiece, surmounted by three statues,
Peace, Plenty, and Harmony, supporting the carved wooden cornice. The
Elizabethan _staircase_ has carved panels of maple. The _library_ is
wainscoted to the ceiling in black walnut, inlaid with ebony. The _dining
room_ is also wainscoted in the richest style in oak, with polished
mahogany panels. The _floors_ are of marquetry, of different woods
and patterns. The _chamber story_ is finished in oak and walnut, with
mahogany in the panels. The _entire interior_ finish of the house is of
hard wood, _varnished and rubbed_ in cabinet style. This is as it should
be for a gentleman’s residence.
We believe the largest house now being erected in London is from the
designs of Mr. Knowles, jun., for Baron Albert Grant, at Kensington.
We have not seen it, but we hope it will be finished in the Cincinnati
style, as far as regards the amount of ornamental woods used.
There is a cynical French proverb, which says, “When we cannot have what
we love, we must love what we have.” But surely this cynical proverb
cannot be applied to “stone colour” paint on wood. The Japanese, however,
some years since, determined not to follow this advice, for when the
English Government, at Admiral Sterling’s suggestion, sent to the Tycoon
a very fine steam vessel, the Japanese (who abhor paint about their
ships) immediately commenced to scrub off the paint. According to Sir
Rutherford Alcock, they have been steadily engaged in scrubbing it off
ever since the boat has come into their possession, and by dint of labour
and perseverance have nearly succeeded. All the fine imitation satin-wood
and the gilt work have been reduced to a very forlorn state. The Japanese
not only decline to follow advice, but they are a very difficult race
of people from whom to obtain correct information. When Mr. Veitch was
at Yeddo, on a visit to the Legation, in quest of botanical specimens,
he saw a pine-tree from which he desired a few seeds. “Oh,” said the
inevitable yaconins, “those trees _have no seed_!”--“But there they are,”
replied the unreasonable botanist, pointing to some. “Ah, yes, true; but
they _will not grow_,” was the reply.
If we must take our fashions from royalty and the aristocracy, and if we
must go abroad for them, surely the above examples will suffice; but if
we must have paint, then the preservative solution, now being extensively
used in the restoration and renovation of St. Paul’s Cathedral, under
the superintendence of Mr. F. C. Penrose, the architect to the Dean and
Chapter, appears to possess several good qualities. The preservative
solution, which is manufactured by the Indestructible Paint Company, is
said to be as follows: 1st, that it is colourless and invisible; 2nd,
in no way does it alter the appearance of the surface; 3rd, it prevents
the growth of vegetation; and 4th, that it resists the action of the
atmosphere and changes of weather, not only preventing but also arresting
decay.
It is necessary that the wood selected (if not to be painted) should
be well grown, and from a fully developed tree, where all the fibres
or grain are distinctly marked. The beauty of the wood, when properly
treated, consists in the brilliant manner in which the rich, deep yellow
streaks or layers of the hard wood are developed under the hands of
the skilful polisher. These yellow veins show through the polish like
clear and beautifully marked streaks of amber; and strongly reflecting
the light, they produce a very pleasing effect. The yellow, variegated,
hard part of the wood forms a very excellent contrast to the delicate
whiteness of the softer parts of the board; and, if skilfully selected,
the effect will be much admired, and certainly preferred to the best
imitation of the more rare and expensive woods. In arranging doors,
panels, &c., much will, of course, depend in selecting the wood, in
placing the best parts in the panels, so that when polished the most
pleasing effects will be produced. Much, too, depends on skilful
workmanship and smooth finish, which can only be obtained by care, and
using well-seasoned wood; but this is the case with all species of wood.
Should any young architect, after reading the preceding remarks, be
desirous of employing natural woods in his building works, we advise
him, before he attempts this kind of colour decoration, to study Mr.
Owen Jones’ lecture on “Colour in the Decorative Arts,” delivered before
the Society of Arts, 1852; and likewise M. Chevreul’s ‘Laws of the
Simultaneous Contrast of Colours’; we also recommend him to--
Use _moderate_ things elegantly, and _elegant_ things moderately.
Oak, walnut, maple, elm, and some other woods become of very dark colour,
but can be made to receive a fine polish, and could often be employed for
panels with good effect. In some cases there is great contrast of tint
in the same log after preparation, so that these might be inapplicable
except in smaller pieces, or perhaps by applying the process after
the work has been made; but sycamore, beech, and some other woods are
generally uniform, except as regards the previous grain of the wood.
As to the matter of showing the end of the grain, according to the Gothic
principle the beauty of a wood consists in showing the end of the grain;
but, at the same time, the classic principle is that there is a greater
beauty in the side way of the grain than in the end way.
Although varnish and polish both form a glazing, and give a lustre to the
wood they cover, as well as heighten the colours of the wood, yet from
their want of consistence they are liable to yield to any shrinking or
swelling, rising in scales or cracking, when much knocked about. Waxing,
on the contrary, resists percussion, but it does not possess in the same
degree as varnish the property of giving lustre to the bodies on which it
is applied; any accidents, however, to its polish are easily repaired by
rubbing.
The woodwork of the Swiss Cottage, at the late Colosseum, London, in the
Regent’s Park, was only varnished.
In using stain on any description of wood, the stain should always be
allowed to get quite dry before sizing, as that gives it a fair chance of
striking into the wood. Glue size is the best for stained work, made so
thin that there is no fear of putting it on in patches. After the size is
quite dry also, varnish; and if the first coat does not stand out quite
sufficiently to please the eye, give it a second coat. Some persons use
stain and varnish together, doing away with size; but this is a very
poor method, for should the wood get scratched or damaged in any way,
the varnish and stain come off together, leaving a white place, if it be
white wood that is stained. A painter who has been in the trade forty
years, recently remarked to us, “You must size, or else the varnish won’t
come out; it won’t show that it _is_ varnish; the wood soaks it up; while
there is any suction going on the varnish’ll go in. The sizing stops all
suction.”
A great many experiments and attempts have been made at different times
to colour wood. John of Verona first conceived the idea. The celebrated
B. Pallissy investigated the cause of the veins, &c., in wood, and tried
mordant solutions applied to the surface, wetting the surface with
certain acids, immersing the wood in water to bring out the veinage, &c.
Ebony has often been imitated by penetrating sycamore, plane, and lime
woods to a certain depth with pyrolignite of iron, gall-nuts, &c.
Werner, in 1812, obtained great success at Dijon in colouring the woods
by filtration. Marloye, in 1833, constructed a machine to colour wood
by placing it erect in a cylinder, sucking out the air at one end, and
forcing up the colouring solution through the other. He gave the credit
of this to Bréant. Marloye has manufactured many mathematical instruments
of wood coloured in this way, _which does not warp_.
If we could afford the space, we would willingly give a _résumé_ of the
attempts of well known experimentalists to colour wood. We can only give
the year and name in each case:
1709. Magnol.
1733. La Baisse.
1735. Hales.
1735. Buffon.
1754. Bonnet.
1758. Du Hamel.
1804. Saussure.
During the recent war between France and Germany, the latter country
advanced matters, their supplies of coloured woods from France being gone.
As we have made so many remarks against painting wood, it is only right
that we should give some description of it, which we will now do.
House painting, according to Mr. W. Papworth, in his lecture on “Fir,
Deal, and House Painting,” 1857, did not come into _general_ use until
about the period of William and Mary, and Anne, up to which time either
colouring by distemper or by whitewash had been in vogue for plaster
work, leaving inside woodwork more or less untouched.
We think, without wishing to think _too loud_, that house painting was
invented by _a bad builder_, in the seventeenth century, because
Putty and paint cover a multitude of sins.
The process of graining and marbling may be traced back as far at least
as the time of James III. of Scotland (1567-1603), during whose reign a
room of Hopetown Tower was painted in imitation of marble. Before that
period, imitations were done in “stone” colour, “marble” colour, wainscot
colour, &c. In 1676, marbling was executed as well as imitations of olive
and walnut woods; and in 1688 tortoise-shell was copied on battens and
mouldings. Mahogany was imitated in 1815, and maple wood in 1817. But why
imitate mahogany, when the grain of the wood differs so much in texture,
and in the appearance of the different and beautiful shades, technically
termed _roe_, _broken roe_, _bold roe_, _mottle_, _faint mottle_, and
_dapple_.
The following description will give the reader some idea of ordinary
painting. The woodwork having been prepared for fixing, has first to
undergo the process of “knotting,” in order to prevent the turpentine
in the knots of fir-wood from passing through the several coats of
paint. One method for best work is to cut out the knot whilst the work
is at the bench to a slight depth, and to fill up the hole with a stiff
putty made of white lead, japan, and turpentine. There are many ways
of killing the knots: the best and surest is to cover them with gold
or silver leaf. Sometimes a lump of fresh slaked lime is laid on for
about twenty-four hours, then scraped off, a coating of “size knotting”
applied, and if not sufficiently killed, they are coated with red and
white lead in linseed oil, and rubbed down when dry. The general method
is to cover the parts with size knotting, which is a preparation of
red lead, white lead, and whitening, made into a thin paste with size.
The most common mode is to paint them with red ochre, which is worth
nothing. The next process is that of priming, which consists in giving
a coat of white and red lead, and a little dryers in linseed oil. This
is the first coat, and upon which the look of the paint on completion
depends. This first, or priming coat, is put on before “stopping” the
work, should that process be required. It consists in filling up with
putty any cracks or other imperfections on the surface of the wood.
If the putty used in the process of stopping be introduced before the
first coat of colour is laid on, it becomes loose when dry. After this
first coat, pumicing is resorted to for removing all irregularities from
the surface. It is worth recollecting that _old_ white lead is much
superior to new for all painting operations. A smooth surface being
thus obtained, the second coat is given, consisting of white lead and
oil: about one-fourth part of turpentine is sometimes added for quick
work. If four coats are to be laid on, this second one has sometimes a
proportion of red lead, amounting to a flesh colour; but if only three,
it is generally made to assume the tint of the finishing coat. It should
have a good body, and be laid even. This coat, when thoroughly dry and
hard, is, in best work, rubbed down with fine sand paper, and then the
third coat, or “ground colour,” applied of a somewhat darker tint than
wanted when finished, having sufficient oil for easy working, but not
too fluid: thus two-thirds oil, and one-third turpentine. The “flatting”
coat follows, the object of which is to prevent the gloss or glaze of
the oil, and to obtain a flat, dead appearance. White lead is mixed with
turpentine, to which a little copal is sometimes added, and when the tint
is put in it is always made lighter than the ground colour, or it would,
when finished, appear in a series of shades and stripes. Flatting must be
executed quickly, and the brush is generally, if not always, carried up
the work, and not across it.
To clean paint, raw alkalies should not be used, as they will infallibly
take off the flatting coat. The best mode of cleaning is by means of
good soap, not too strong, laid on with a large brush, so as to make a
lather: this should be washed off clean with a sponge, and wiped dry with
a leather.
We must draw to a conclusion.
One cause of the decay of modern buildings, and frequent cases of
dry rot, is owing to the employment of bad builders. We advise the
non-professional reader to employ an architect or surveyor when he
desires to speculate in bricks and mortar: it is the cheapest course. If
he doubts the truth of what we have written, we can assure him he will be
a mere child in the hands of a bad or scamping builder; that is to say,
he will obtain a badly-erected house,--a cheap contract, and a long bill
of extras.
There are _seven_ classes of bad builders--1st, the _bad builder_ who
does not know his business; 2nd, the _bad builder_ who has no money to
carry it on with; 3rd, the _partial_ scamp; 4th, the _regular_ scamp;
5th, the _thorough_ scamp; 6th, the “_jerry_” builder; and 7th, the
_vagabond_. There is an instance of the latter class given by Mr. Menzies
in his fine work on ‘Windsor Park,’ 1864. We could give examples of all
these classes, and draw the line between each class, impossible as it may
seem: they are always looking out for customers, _without architects_.
We could assist the non-professional reader by quoting the advice
given by several architects (viz. Sir C. Wren, C. Barry, B. Smirke, W.
Chambers, and W. Tite) relative to buildings, but there is a Danish
proverb which, translated into English, runs as follows: “He who builds
according to every man’s advice will have a crooked house.”
CHAPTER VII.
ON THE PRESERVATION OF WOODEN BRIDGES, JETTIES, PILES, HARBOUR WORKS,
ETC., FROM THE RAVAGES OF THE TEREDO NAVALIS AND OTHER SEA-WORMS.
“Perforated sore
And drilled in holes, the solid oak is found
By worms voracious, eaten through and through.”
SIR JOHN BARROW.
As the destruction of timber by fungi has been called the _vegetable_
rot, it may not be inappropriate to term the destruction of wood by
various worms and insects, the _animal_ rot.
We have _four natural enemies_ to deal with: 1st, the _dry rot_, that
attacks our houses, &c.; 2nd, the _worms_, or boring animals, which
destroy our ships and harbours; 3rd, the _rust_, that eats our iron; and
4th, the _moisture and gases_, that destroy our stone.
There are three classes of destructive insects which prey upon
timber trees, founded upon the manner in which they carry on their
operations--viz. those which feed upon the leaves and tender shoots;
those which feed upon the bark and the albumen; and those which feed upon
the heart-wood.
It is to be observed that some of the insects which feed upon the heart
of wood do not cease their ravages upon the removal of the tree; but
that, on the contrary, the _Cossus syrex_, of our indigenous fauna, and
the larvæ of the _Callidium bajutum_, which are often found in imported
timber, continue to devour the wood long after it has been inserted in
buildings. There seem to be very few means of defence against this class
of destructive agents; and very few trustworthy indications of their
existence, or of the extent of the ravages they have committed, are to
be discovered externally; and it thus frequently happens that a sound,
hearty-looking stick of timber may be so seriously bored by these insects
as to be of comparatively little value for building purposes of any
description. The soft and tender woods, and such as are of a saccharine
nature in their juices, are the most liable to be assailed by worms;
those which are bitter are generally, if not invariably, exempt; it is
obvious, therefore, that those palatable juices, which are so conducive
to their production and propagation, should be got rid of by thorough
seasoning, and, if further precaution be necessary, that the infusion of
some bitter decoction into the pores of the wood will be an effectual
preventive; and for which those woods that are of a regular grain afford
sufficient facilities. Ash, if felled when abounding in sap, is very
subject to worms; beech, under similar circumstances, is also liable to
their attacks; likewise alder and birch; in these woods water seasoning
is sometimes found to be a good preventive; the sapwood of oak is also
thus improved; the silver fir is subject to them; the sycamore is rather
so; alder is said when dry to be very susceptible of engendering them;
the cedar, walnut, plane, cypress, and mahogany are examples of woods
which discourage their advances. It has been stated that Robert Stevenson
(not the son of the “Father of Railways”), of Edinburgh, at Bell Rock
Lighthouse (of which he was engineer), between 1814 and 1843, found that
greenheart wood, beef wood, and bullet tree were not perforated by the
_Teredo navalis_, and teak but slightly so. Later experiments show that
the “jarrah” of the East, also, is not attacked. Lignum vitæ is said to
be exempt. The cost of these woods prevents their general use.
In 1810, Stevenson first noticed the _teredo_ in piles, and specimens
of the creatures in wood were sent to Dr. Leach, of the British Museum,
in 1811, who examined them, and noticed their peculiarities. Stevenson,
settled on Bell Rock during many years (like a new Robinson Crusoe), was
enabled to watch the injuries done to the piles by the _teredo_. With
piles which had been subjected to Kyan’s process before immersion, the
wood was attacked at the end of the twenty-eighth month, and was entirely
destroyed in the seventh month of the fifth year. With Payne’s, it lasted
a year longer.
We can give the names of those who have given much time and attention
to this subject. At the bottom of this page a list of works of
reference[16] will be found useful. Messrs. Stevenson (engineer of Bell
Rock Lighthouse), Harting (Member of the Academy of Sciences of the
Pays-Bas), de Quatrafages, Deshayes, Caillaut, Hancock, Dagneau, de
Gemini, Kater, Crepin (Engineer-in-Chief, of Belgium), and A. Forestier
(Engineer-in-Chief of the Bridges, &c., of France).
The termite, or white ant, is the most destructive insect to timber on
land, whilst the teredo reigns supreme of sea worms in the sea. The
former we shall treat of in our next chapter, the latter we propose
considering at some length in this.
The marine worm, of which there are accounts in all parts of the world,
has been known, by its effects, for hundreds of years; indeed, Ovid spoke
of it nineteen hundred years ago, and it is even mentioned by Homer.
Fossil _terredines_ of great antiquity have been found near Southend;
also pieces of petrified wood from the greensand, near Lyme and Sidmouth,
bored by ancient species of _teredo_; also from Bath, and from Doulting,
near Shepton Mallet, specimens of oolite, with petrified corallines in
it, pierced by boring shells.
It is said that this worm is a native of India, and that it was
introduced to Holland some 200 years ago, from whence it has spread
through the ports of northern Europe.
The _Teredo navalis_[17] is very destructive to harbour works and piling.
The Southampton water is particularly infested with it; in fact, the
_teredo_ is found in every port to which coals are carried south of the
Tees; in the Thames, as high up as Gravesend; and northward as far as
Whitby. It is also found at Ryde, Brighton, and Dover. Traces of the
ravages of the _Teredo navalis_, and of the _Limnoria terebrans_, have
at various periods been found from the north of Scotland and Ireland, on
almost every coast, to the Cape of Good Hope and Van Dieman’s Land, in
the eastern hemisphere; and, in the western hemisphere, from the river
St. Lawrence to Staten Island, near Terra del Fuego, almost in the Polar
Sea; so that although this maritime scourge is rifest in warm climates,
yet cold latitudes are not exempt from it.
At the Crystal Palace, Sydenham, may be seen the destructive _Teredo
navalis_ in a bottle, and there may also be seen mahogany perforated by
it, and fir piles from Lowestoft Harbour, which were rendered useless by
the ravages of the worm and the _limnoria_ three years after they were
driven, showing the necessity of defending timber intended for marine
construction. A specimen of American oak from the dock gates of Lowestoft
Harbour, which had been four years under water, and a part of a fir-pile
from the dockyard creek at Sevastopol, also show the destructive powers
of the _teredo_. At the South Kensington and British Museums, London,
specimens of this worm may also be seen, as well as pieces of timber
perforated by it.
The bottoms of ships, and timbers exposed to the action of the sea, are
often destroyed by the _teredo_.
The gunboats constructed during the Crimean war suffered far more from
dry rot and the _teredo_ than the shot and shell of the Russians. One
cannot even guess at the mischief perpetrated every year all along our
shores, in docks and harbours, by the boring animals that penetrate all
woods not specially protected. We cannot count the number of the ships
that have foundered at sea, owing to those few inches of timber, on which
all depended, being pierced or destroyed by the worm or fungus.
In the short space of twelve years these destructive worms were known
to make such havoc in the fir piles of a bridge at Teignmouth, that the
whole bridge fell suddenly, and had to be totally reconstructed.
The wooden piers of Bridlington were nearly wholly destroyed by worms;
and the pile fenders on the stone piers at Scarborough were generally cut
through in a few years.
At Dunkirk, wooden jetties are so speedily eaten away that they require
renewal every twelve or fifteen years. At Havre, a stockade was entirely
destroyed in six months. At Lorient, wood only lasts about three years
in the sea-water; and at Aix, the hull of a stranded vessel was found
to have lost half its weight in six months, from the ravages of these
animals.
The reason why Balaclava, in Russia, is not a place of considerable
mercantile importance is owing in a great measure to the destructive
ravages of the worms with which its waters are infested, and by which the
hulls of ships remaining there for any length of time become perforated.
The piles of the jetties in Colombo Harbour, Ceylon, which are mostly
of satin-wood, and about 14 inches in diameter, are so pierced by these
worms in the course of twelve months as to require renewal.
[Illustration: _Portion of pile, from Balaclava harbour, Russia; riddled
by the Teredo Navalis._]
The cofferdam at Sheerness was destroyed by the _teredo_. After a time,
it was no uncommon occurrence to see several piles, apparently sound,
floated away at each tide; indeed, they were so thoroughly perforated by
the _teredo_ that in still weather, by putting the ear to the side of the
pile, the worms could be heard at their boring labours.
The almost total destruction of the pier-head of the old Southend Pier
in a few years, is another instance of the serious damages these worms
cause. The old pier-head was erected in the year 1833, and in three years
the majority of the wooden piles had been almost destroyed, and at the
end of ten years, in addition to the piles being all eaten through by
the worms, the whole structure had sunk 9 inches at the western end, so
that in a short time it would have fallen. The materials with which the
work was constructed were of good quality, the fir being Memel, and the
oak of English growth; it was all perfectly sound in those places were
the _teredo_ had not attacked it, and indeed portions of it were again
used in the construction of the extension of the pier. The whole of the
timber work was well coated with pitch and tar previously to being fixed,
but notwithstanding these precautions, and an apparent determination
to protect the pier-head by copper sheathing, brushing, cleaning, and
constant watchfulness, the _teredo_ made its appearance, and committed
such ravages that the entire destruction of the pier-head soon appeared
inevitable. The _Teredo navalis_ first showed itself six months after the
completion of the work, and was reported within twelve months to have
seriously injured the piles above the copper, whilst at about low-water
mark, of neap tides, nearly all the piles exhibited appearances of
destruction, the _limnoria_, as well as the _teredo_, having seriously
attacked them; and in less than four years from the completion of the
pier-head, they had progressed in their work to such an extent that
some of the piles were entirely eaten through, both above and below the
copper sheathing; in consequence of this the stability of the structure
was materially injured, and, on examination, it was discovered that
the ground had been considerably washed away by the action of the sea,
and that the piles below the copper were exposed to the action of the
_teredo_.
The first appearances of the _Teredo navalis_ are somewhat singular,
inasmuch as the wood which has been perforated by it presents to the
casual observer no symptom of destruction on the surface, nor are the
animals themselves visible, until the outer part of the wood has been
broken away, when their shelly habitations come in sight, and show the
perfect honeycomb they have formed; on a closer examination of the wood,
however, a number of minute perforations are discovered on the surface,
generally covered with a slimy matter; and on opening the wood at one of
these, and tracing it, the tail of the animal is immediately found, and
after various windings and turnings, the head is discovered, which, in
some cases, is as much as 3 feet from the point of entrance; sometimes
it will happen, especially if the wood has been much eaten, that their
shelly tubes are partly visible on the surface, but this is rare; they
enter at the surface, and bore in every direction, both with and against
the grain of the wood, growing in size as they proceed.
The Rev. W. Wood writes, in 1863: “I have now before me a portion of
the pier at Yarmouth, which is so honeycombed by this terrible creature
that it can be crushed between the hands as if it were paper, and in
many places the wood is not thicker than ordinary foolscap. This piece
was broken off by a steamer which accidentally ran against it; and
so completely is it tunnelled, that although it measures 7 inches in
length and about 11 in circumference, its weight is under 4 ounces, a
considerable portion of even that weight being due to the shelly tubes of
the destroyers.”
The eggs of the _teredo_ affix themselves to the wood they are washed
against, are then hatched, and the worm commences boring; each individual
serves by itself for the propagation of the species; and they rarely
injure each other’s habitations. Any timber, constantly under water,
but not exposed to the action of the air at the fall of the tide, is
extremely likely to be destroyed by them. They appear to enter the wood
obliquely, to take the grain of the fibre, and more generally to bore
with it downwards, where the perforations are left dry at low water.
It has been stated by some authorities that the _teredo_ is only a
destructive creature, and seeks the wood as a shelter, from instinctive
dread of some larger animals, but there is no doubt this insect feeds
upon wood. Mr. John Paton, C.E. (to whom we are indebted for much
information on these worms), in conjunction with Mr. Newport, the eminent
physiologist and anatomist, on carefully dissecting this animal for the
purpose of ascertaining its general character, and more particularly the
nature of its food, found digested portions of wood in its body, so
that there is no doubt that the _teredo_ does feed upon the particles of
the wood, and to this its rapid and extraordinary growth must be mainly
attributed.
[Illustration: _The Lyceris, which destroys the Teredo Navalis._
_The Teredo Navalis, which destroys wood._
_Portion of Timber pile destroyed by Sea Worms._]
The _Teredo navalis_, or, as it is sometimes called, the Ship Worm, is
one of the _Acephalous mollusca_, order Conchifera, and of the family
of the _Pholadariæ_. It is of an elongated vermiform shape, the large
anterior part of which constitutes the boring apparatus, and contains
the organs of digestion, and the posterior, gradually diminishing in
size, those of respiration. The body is covered with a transparent
skin, through which the motion of the intestines and other remarkable
peculiarities are plainly visible. The posterior or tail portion is
armed at its extremity, with two shells, and has projecting from it a
pair of tubular organs, through which the water enters, for the purpose
of respiration; this portion is always in the direction of the surface,
and apparently in immediate contact with the water, but does not bore.
The anterior portion of the animal is that by which it penetrates the
wood, being well armed for the purpose by having, on each side, a pair of
strong valves, formed of two pieces, perfectly distinct from one another;
the larger piece protects the sides and surface of the extremities, and
has a shelly structure projecting from the interior, to which the muscles
are attached; the smaller piece is more convex, and covers that part
which should be regarded as the anterior surface of boring. This portion
of the shell is deeply carniated, and seems to constitute the boring
apparatus. The shells form an envelop around the external tegument of
the animal, which even surrounds the foot, or part by which it adheres
to the wood. The neck is provided with powerful muscles. The manner in
which it appears to perforate the wood is by a rotary motion of the foot,
carrying round the shells, and thus making those parts act as an auger,
which is kept, or retained in connection with the wood, by the strong
adherence of the foot. The particles of wood removed by this continued
action of the foot, and the valves, are engorged by the animal, for
between the junction of the two large shells there is a longitudinal
fissure in the foot, which appears to be formed by a fold of this portion
of the two sides, thus forming a canal to the oral orifice, and along
which the particles of wood bored out, are conveyed to the mouth. The
mouth, or entrance to the digestive organs, is of a funnel shape, and
consists of a soft, or membraneous surface, capable of being enlarged,
and leading into an œsophagus, which passes backwards towards the dorsal
surface of the animal. At or near the termination of the œsophagus, there
is a glandular organ, the use of which is possibly to secrete a fluid for
assisting in the digestion of the wood, and not, as has been supposed, to
act as a solvent; for if such were the case, it would most probably be
situated at its commencement instead of at its termination. At a short
distance behind this organ are two other large glandular bodies, the
use of which may also be to secrete fluid for the purpose of digestion.
The œsophagus terminates in a large dilatation, into which these organs
pour their contents; at its posterior end the canal is dilated into a
very large elongated sac, which extends backwards to about one-fourth
of the length of the whole animal, and is filled with food, while from
its anterior, or upper surface, it has an oval, muscular formation, from
which the alimentary canal is continued forwards, and, after making a few
turns, passes backwards, in an almost direct line, on the upper surface
of the large sac, again passing backwards and forwards, until it finally
arrives at its termination, which it passes round, and then proceeds, in
a direct line, to the anal outlet. In the lower portion of the œsophagus,
and also in the sac, distinct portions of woody fibre of an extremely
minute character were found by the aid of the microscope of a power of
three hundred, and this was the character of the whole of the contents of
the alimentary canal.
The _teredo_ lines the passage in the wood with a hard shell; this shell
is formed around, but does not adhere to the body; it is secreted by the
external covering, which, in its first formation, is extremely fragile,
but becomes hardened by contact with the water, and adheres to the wood,
from which it may, however, be easily detached. The interior of this
shell is not filled by the body of the _teredo_, but a large space around
it is occupied with water, admitted through the small orifice in the
surface of the wood through which the animal first entered; the water
being drawn through the respiratory tubes, into the bronchial cavity
of the body, is expired again through the same orifice, and this, in
conjunction with the valve-like shells attached at this part, induces a
current round the animal which removes the excreted fœtal matter. The
shells are very smooth on the inner surface, but are somewhat rougher
on the exterior; they are much harder and firmer in the cells of the
older animals than in the young ones, and are composed of several annular
parts, differing greatly in their length.
It is no less curious than wonderful to observe the mysterious instinct
which apparently regulates the mechanical skill of the _teredo_, its
own body supplying it with an implement of such admirable consistency
and adaptation as to enable it to excavate a habitation for itself, so
accurately formed that to a casual observer it would appear a mystery how
so perfect a circle could be produced. It is only on examination that the
raised and hollow parts of the wood become visible, and explain, in some
degree, the auger-shaped contrivance that has been used for the purpose
of perforating.
It has already been stated, that the wood is perforated by a rotary
motion of the foot, the adhering part of which acts as a fulcrum,
carrying round the shells, and thus giving immense power to the animal in
its operations.
It is said that when Brunei was considering how to construct the Thames
Tunnel, he was one day “passing through the dockyard (at Chatham, where
he was employed by Government), when his attention was attracted to an
old piece of ship-timber which had been perforated by that well-known
destroyer of timber--the _Teredo navalis_. He examined the perforations,
and subsequently the animal. He found it armed with a pair of strong
shelly valves, which enveloped its anterior integuments; and that, with
its foot as a fulcrum, a rotatory motion was given by powerful muscles to
the valves, which, acting on the wood like an auger, penetrated gradually
but surely; and that, as the particles were removed, they were passed
through a longitudinal fissure in the foot, which formed a canal to
the mouth, and so were engorged. To imitate the action of this animal
became Brunei’s study. ‘From these ideas,’ said he, ‘by slow and certain
methods; which, when compared with the progress of works of art, will be
found to be much more expeditious in the end.’”[18]
Professor Owen suggests that the power of the _teredo_ to bore into wood
depends on muscular friction, the muscular substance being perpetually
renewed while the wood wastes away, of course, without renewal. Professor
Forbes, Dr. Carpenter, and Dr. Lyon Playfair were appointed about
twenty-five years ago by the British Association to examine into the
natural history and habits of these boring animals, but they did not
arrive at any definite conclusion as to whether the boring action of the
_teredo_ was mechanical or chemical. Dr. Deshayes, on his return from
Algiers, after making accurate drawings and careful investigations, came
to the conclusion that the borings were effected by an acid secretion.
Mr. Thomson, of Belfast, examined the operations of the _teredo_ on the
pier at Port Patrick, and arrived at the same conclusion. The general
opinion, however, is that the boring action is a mechanical one.
Although the _teredo_ appears to penetrate all kinds of timber, that
which it seems to destroy with the greatest ease is fir, in which it
works much more speedily and successfully than in any other, and perhaps
grows to the greatest size. In a fir pile, taken from the old pier-head
at Southend, a worm was found 2 feet long and ¾ inch in diameter, and
indeed they have been heard of 3 feet in length and 1 inch in diameter.
The soft, porous nature of the wood is no doubt the cause of their rapid
growth, for in oak timber they do not progress so fast, or grow to so
great a length, though in Sir Hans Sloane’s ‘History of Jamaica’ (1725)
there are accounts of these animals destroying keels of ships made of
oak, and even of cedar, although the latter is renowned, by its smell and
resin, for resisting all kinds of worms.
[Illustration: _Shell left by the Teredo Navalis._
_Cell formed by the Teredo Navalis showing method of boring._]
There is another kind of worm which is very destructive to timber,
which Smeaton observed in Bridlington piers. This is the TIMBER-BORING
SHRIMP, or GRIBBLE, the _Limnoria terebrans_ (or _Limnoria perforata_,
Leach), a mollusc of the family _Asselotes_, Leach. The _Limnoria
terebrans_ is very abundant around the British shores. Its ravages were
first particularly observed in the year 1810, by the late Sir. Robert
Stevenson, engineer of the Bell Rock Lighthouse. While engaged in the
erection of that structure he found the timber of the temporary erections
to be soon destroyed by the attacks of the _limnoria_. So little was
known of the _limnoria_ at the time that Dr. Leach, a well-known
naturalist, who received some specimens from Mr. Stevenson, in 1811,
declared it to be a new and highly interesting species. In 1834, the
late Dr. John Coldstream wrote a very full and interesting description
of the creature. The _limnoria_ resembles a woodlouse, and is so small
as hardly to be perceptible in the timber it attacks, being almost of
the same colour. Small as is this crustacean, hardly larger indeed than
a grain of rice, it is a sad pest wherever submarine timber is employed,
for it works with great energy, and its vast numbers quite compensate
for the small size of each individual; for as many as twenty thousand
will appear on the surface of a piece of a pile only 12 inches square. It
proceeds in a very methodical manner, and makes its way obliquely inward,
unless it happens to meet a knot, when it passes round the obstacle and
resumes its former direction. The surface of the timber being first
attacked, it proceeds progressively into the wood to the depth of about
1½ inch: the tunnels being cylindrical, perfectly smooth winding holes,
about ⅟16th inch in diameter: it is necessary that the holes should
be filled with salt water. The outward crust formed by these attacks
then becomes macerated and rotten, and is gradually washed away by the
beating of the sea. The _limnoria_ does not work by means of any tool or
instrument like the _teredo_, but is supposed to possess some species
of dissolvent liquor, furnished by the juices of the animal itself. Dr.
Coldstream was of opinion that the animal effects its work by the use of
its mandibles. From ligneous matter having been found in its viscera,
some have concluded that it feeds on the wood, but since other molluscs
of the same genus, _Pholas_, bore and destroy stonework, the perforation
may serve only for the animal’s dwelling. The _limnoria_ seems to prefer
tender woods but the hardest do not escape: teak and greenheart are about
the only woods it does not attack. The rate at which the _limnoria_ bores
into wood in pure salt water is said to be about one inch in a year;
but instances have occurred in which the destruction has been much more
rapid. At Lowestoft Harbour, square 14 inch piles were in three years
eaten down to 4 inches square. At Greenock, a pile 12 inches square was
eaten through in seven years. It is stated that a 3-inch oak plank, 12
feet long, would be entirely destroyed in about eight years. Joists
of timber have been found at Southend Pier, 2 feet and 3 feet below
high-water mark, where they had made rapid destruction. The _limnoria_
almost always works just under neap tides; it cannot live in fresh
water, and whilst it is destroying the surface of a pile, the _teredo_
is attacking the interior: sometimes the former is found attacking the
same timber as the Chelura. As with most of these creatures, the male
_limnoria_ is smaller than the female, being about one-third her size.
The female may be distinguished by the pouch in which the eggs and
afterwards the young are carried. About six or seven young are generally
found in the pouch.
The WOOD-BORING SHRIMP (_Chelura terebrans_) is a crustacean that nearly
rivals the _teredo_ itself in its destructive powers. It makes burrows
into the wood, wherein it can conceal itself, and at the same time
feast upon the fragments, as is proved by the presence of woody dust
within its interior. Its tunnels are made in an oblique direction, not
very deeply sunk below the surface, so that after a while the action of
the waves washes away the thin shell, and leaves a number of grooves
on the surface. Below these, again, the creature bores a fresh set of
tunnels, which in their turn are washed away, so that the timber is soon
destroyed in successive grooved flakes.
According to Mr. Allman, its habits can be very easily watched, as if
it is merely placed in a tumbler of sea water, together with a piece of
wood, it will forthwith proceed to work, and gnaw its way into the wood.
The apparatus with which it works this destruction is a kind of file or
rasp, which reduces the wood into minute fragments. In this creature
the jaw feet are furnished with imperfect claws, and the tenth segment
from the head is curiously prolonged into a large and long spine. The
great flattened appendages near the tail seem to be merely used for the
purpose of cleaning its burrow of wood dust which is not required for
food. The creature always swims on its back, and when commencing its work
of destruction, clings to the wood with the legs that proceed from the
thorax. The wood-boring shrimp is one of the jumpers, and, like the sand
hopper, can leap to a considerable height when placed on dry land. It
has been detected in timber taken from the sea at Trieste. It was first
observed as an inhabitant of the British seas several years ago, by Mr.
Robert Ball, of Dublin, and in January, 1847, it was described by Mr.
Mullins, C.E., in a paper read before the Institution of Civil Engineers
of Ireland, as being very injurious to the timber piles in Kingstown
Harbour, near Dublin, and far more destructive than the _Limnoria
terebrans_.
[Illustration: LIMNORIA TEREBRANS. FEMALE. MALE.
A. B. C. HEAD OF THE TEREDO NAVALIS.
RASP OR FILE OF THE CHELURA. CHELURA TEREBRANS.
ELEVATION OF PILES, SOUTHEND PIER, DESTROYED BY THE “TEREDO” AND
“LIMNORIA” ABOVE AND BELOW THE COPPER SHEATING.]
We have already referred to the _lesson_ the celebrated engineer,
Brunel, received from observing the _teredo_; and we can state that
architects have also received _lessons_ from nature. Sir Christopher
Wren constructed his spire of St. Bride’s Church, London, after observing
the construction of the delicate shell, called _Turretella_, which has
a central column, or newel, round which the spiral turns. Brunelleschi
designed the dome of Sta. Maria, at Florence, after studying the bones
of birds and the human form; and Michael Angelo followed Brunelleschi in
constructing the dome of St. Peter’s, Rome.[19]
The LEPISMA is also a destructive little animal, which begins to prey
on wood in the East Indies, as soon as it is immersed in sea water. The
unprotected bottom of a boat has been known to be eaten through by it in
three or four weeks.
These worms, it must be remembered, do not live except where they have
the action of the water almost every tide, nor do they live in the parts
covered with sand. The wooden piles of embankments and sea locks suffer
very much from their depredations, and in the sea dykes of Holland they
cause very expensive annual repairs.
The Dutch used to coat their piles with a mixture of pitch and tar, and
then strew small pieces of cockle and other shells, beaten almost to
powder, and mixed with sea sand, which incrusted and armed the piles
against the attacks of the _teredo_. We believe it was a frequent
practice in London, about half a century ago, to place small shells in
the wooden pugging between the floor joists to deaden sound.
Having described the chief peculiarities of these worms, shown their
mode of working, and the extent to which their destructive powers may be
carried, it will now be necessary to consider the various schemes which
have been proposed and tried to prevent their desolating ravages. These
may be divided into _three_ classes, viz. the natural, chemical, and
mechanical.
1st. By using woods which are able to resist the attacks of sea worms.
2nd. By subjecting piles to a chemical process.
3rd. By adopting a mechanical process.
First. We have not any English woods which resist their attacks. Elm
(used for piles in England) or beech (used for piles, if entirely under
water, in France) cannot withstand the _teredo_; while oak cannot battle
successfully against wood-beetles in carvings. It is therefore necessary
to inquire whether foreign woods are any better.[20] Unfortunately the
great expense of importing them into England prevents their use for piles.
Nearly all our foreign woods used for engineering and building purposes
come from the Baltic or Canada: they are fir and pine. Memel timber from
the Baltic is comparatively useless unless thoroughly creosoted; and
Canadian timber is not so good as the Baltic wood. At Liverpool and some
of the western ports of England Canadian timber is preferred to Baltic,
although we believe the reason to be that they cannot get the latter,
except in small quantities at a time.
The following is a list of timber woods which, according to good
authorities, resist for a long period of time the attacks of sea worms.
It should be borne in mind, however, that the timber should be cut,
during the proper season, from a large and full-grown tree; and, to
prevent splitting, it should be kept from the direct action of the sun
when first cut; it should have all the bark and sapwood removed, and
allowed to dry a certain time before being used.
WOODS WHICH RESIST SEA WORMS.
_Australia, Western._--Jarrah, beef-wood, tuart.
_Bahama._--Stopper-wood.
_Brazil._--Sicupira, greenheart.
_British Guiana._--Cabacalli, greenheart, kakarilly, silverballi
(yellow).
_Ceylon._--Halmalille, palmyra, theet-kha, neem.
_Demerara._--Bullet, greenheart (purple heart-wood), sabicu.
_India._--Malabar teak, sissoo, morung sál, dabu, than-kya,
ilupé, anan, angeli, may-tobek. (Teak resists the _teredo_, but
is not proof against barnacles.)
_Jamaica._--Greenheart.
_North America._--Locust.
_Sierra Leone._--African oak, or tortosa.
_South America._--Santa Maria wood.
_Philippine Islands._--Malacintud, barnabá, palma-brava.
_Tasmania._--Blue gum.
_West Indies._--Lignum vitæ.
Second. The chemical, viz. Kyan’s process of corrosive sublimate; Payne’s
process of sulphate of iron and muriate of lime; pitching and tarring;
Burnett’s process of chloride of zinc; and arsenic, or other mercurial
preparations, have all failed, with the exception of Bethell’s process of
oil of tar. The failure must proceed from one of two causes; either that
the sea-water decomposes the poisonous ingredients contained in the wood,
or that these poisonous compounds have no injurious effect on the worms;
it appears, however, that both these causes have been in operation,
principally the latter.
Without a series of the most minute experiments, it is impossible to
form any general notion of the action of sea-water on timber. Common
salt, chlorides of calcium and magnesium, sulphate of soda, iodides
and bromides of the same metals, are known to exist in sea-water, and
in great abundance in the torrid zone. What effect these different
ingredients may have upon saturated timber it is difficult to say, but it
is extremely probable that they do have an effect.
With regard to the different poisonous compounds having no injurious
effect on the worms, it should be remembered that all cold-blooded
animals are much more tenacious of life than those of a higher
temperament, and in descending the scale of animal creation, the tenacity
of life increases, and this principle is more developed. A frog, which
though cold-blooded, is an animal of a much higher order than the
_teredo_, will not only live in hydrogen gas, but also in a strong
solution of hydrocyanic acid, while at the same time a single drop placed
on the nose of a rat, or in the eye of a rabbit, would produce instant
death. A somewhat similar occurrence is noticed in the ‘British and
Foreign Medical Review,’ for July, 1841, showing the slow effects of
prussic acid on the common snake and turtle.
It may therefore be inferred, that as it requires a large quantity of the
most virulently poisoned matter to destroy animals of a much higher order
than the _teredo_, it would take a still greater quantity to affect those
animals as they exist in their own element.
The preserving property of soluble salts, such as corrosive sublimate,
sulphate of copper, &c., was considered to be founded upon their power
of coagulating the albumen, and the sap of wood, thereby rendering that
sap less liable to decay; but that very quality of combining with the
albumen, destroyed the activity of the poison of the salts. A given
quantity of corrosive sublimate of mercury, which if administered to a
dog would kill it, would, when mixed with the white of an egg, become
coagulated, and if swallowed in that state would be perfectly harmless;
so a piece of wood, saturated by those salts, could be eaten by a worm
without injury.
A French naturalist, M. de Quatrefages,[21] in 1848, suggested that a
weak solution of mercury (corrosive sublimate) thrown into the water will
destroy the milt of the _teredo_, and consequently prevent fecundation
of the eggs, thus exhausting the molluscs in the bud. He proposed that
ships should be cleared of this terrible pest by being taken into a
closed dock, into which a few handfuls of corrosive sublimate should
be thrown and well mixed with the water. He considered that about 1
lb. of sublimate would be sufficient for 20,000 cubic metres (metre =
39·37 English inches) of water; but on account of the cost it would
be advisable to use salts of lead or copper. This proposition of de
Quatrefages reminds us of Chapman’s suggestion, in 1812, to get rid of
dry rot in ships, viz. by sweeping out the hold, laying from two to four
tons of copperas in her bottom, and as much fresh water let in upon it as
would make a saturated solution to soak into the wood.
M. de Quatrefages placed the four salts he used in his experiments in
the following order, according to merit: 1st, corrosive sublimate; 2nd,
acetate of lead; 3rd, sulphate of copper; and 4th, nitrate of copper.
In America, white oxide of zinc is used as a marine paint for ships
and piles. In the United States Navy Yard at Gosport it is spoken well
of, and very frequently employed. It is said to be much superior to
white-lead, red-lead, verdigris, or coal-tar, and that timber covered
with two coats of white zinc is neither attacked by the worm, nor do
barnacles attach to it when immersed in salt water.
We can only find one instance of timber impregnated with water-glass
having been tested against this subtle foe. Water-glass is certainly
worth a further trial.
The instance we refer to occurred about forty years ago. In 1832,
Dr. Lewis Feuchtwanger, of New York, was permitted by the Ordnance
Department, under the direction of Commodore Perry, to perform
experiments with water-glass on piles in the Brooklyn Navy Yard, and in
various docks. The piles in the docks were destroyed by the _teredo_ so
fast that they _had to be replaced every three years_. The experiments
proved highly satisfactory: the piles which had been so treated lasting
many years, without any indication of being attacked by sea-worms.
The reader is referred to some works on water-glass mentioned below,[22]
which are worthy of attentive perusal.
Third. The mechanical processes. They are few in number, and rather
expensive.
At Saint Sebastian, in Spain, the piles of the wooden bridge standing
in the sea have been guarded against the attacks of sea-worms in the
following manner: Each pile is surrounded by a wooden box, and the space
between filled up with cement. After six years it was proved that the
piles were in a perfect condition, whilst the outer boxes were completely
riddled by the worms. A similar method to this was adopted, some years
since, to many of the piles in the Herne Bay Pier, which were affected
by sea-worms. Several attempts had been made to protect the timber, by
saturating it under various processes, with, however, only doubtful
success. At last, a wooden casing was formed round each pile, leaving
a space of about an inch all round, which was rammed full of lime or
cement concrete. That process appeared to be perfectly successful, as the
pier-master, who first adopted the method, stated that some of the piles
had been so treated for three or four years, and although the worms had
commenced their ravages, they appeared to have been checked, and not to
have been able to exist when so enclosed.
In 1835, Brunel suggested an easy way of defending piles, which was to
give them in the first instance a coat of tar; then powder them with
brick-dust, which would render the wood sufficiently hard to receive a
coat or two of cement. This is similar to the Dutch method.
Some foreigners use sheet lead nailed on to piles, and wrapped close
round with well-tarred rope.
Copper sheathing has often been used for the protection of piling in
piers and harbours. The destruction of copper by the action of sea-water
is a matter which has long occupied the attention of scientific men, and
it appears to be well ascertained that the decay does not result from the
bad quality of the copper, for, according to Mr. Wilkinson, no difference
could be discovered between the composition of copper that had endured
well, and that which had been rapidly destroyed. Copper sheathing was
used at Southend, but without success, for although nearly all the piles
were covered with it for about 9 feet or 10 feet, the _limnoria_ not only
penetrated between the copper and the timber, but the copper had decayed
to such an extent as in some cases to be no thicker than the thinnest
paper; it was soft, and peeled off the wood very easily, and in two or
three years would probably have been entirely destroyed.
Covering the surface of the timber with broad-headed scupper nails,
arranged in regular rows with their heads at no great distance from each
other, is a method which has been satisfactorily employed in various
parts of the world, in Swedish and Danish vessels, even up to the
present time, and, indeed, it was also practised by the Romans. The
scupper-nailed piles at Southend, after twelve years’ exposure to the
sea, were perfectly sound, and although the nails were not driven close
together in the first instance, yet the corrosive action was so great as
to form a solid impenetrable metallic substance, upon which the worms
refused to settle. Scupper nails have been proved at Yarmouth, as well
as at other places, to have protected timber for forty years, but the
process is expensive, as it costs one shilling per square foot. They
should be about half an inch square at the head.
Captain Sir Samuel Brown, R.N., states that from numerous experiments and
observations, he is satisfied that at present there is really no specific
remedy against the attacks of sea-worms upon timber, except iron nails.
He proposes to encase the piles with broad-headed iron nails resembling
scupper nails, but considerably larger, and he says that in the course of
a few months corrosion takes place, and spreads into the interstices. The
rust hardens upon the pile, and becomes a solid mass which the worm will
not touch. Experiments tried at the Trinity Pier, Newhaven, and Brighton
Pier, have established the effectiveness of his method.
At the Cape of Good Hope, and many other places, wood piles are cased
in iron, and occasionally iron piles are used instead of wood, at great
cost. Further experience is desirable as to the durability of cast
iron[23] in salt water, especially as to its peculiar property of
conversion, after a few years’ immersion in the sea, into a carburet of
iron, closely resembling plumbago, so that it may be easily cut with
a knife. This, of course, diminishes its powers of resistance acting
upon the framing it is intended to strengthen. In the course of the
construction of the Britannia Bridge, about one hundred thin plates
were delivered, which were not used on account of some error in their
dimensions. They were left on the platform alongside the straits,
exposed to the wash and spray of the sea; and after about two years were
literally so completely decomposed as to be swept away with a broom into
the water, not a particle of iron remaining.
We have already stated that the chemical processes have failed with the
exception of Bethell’s process of oil of tar, generally known as the
creosoting process. This method, _when properly carried out_, thoroughly
protects wood from the ravages of the _teredo_ and other marine worms.
The breakwaters and piers at Leith, Holyhead, Portland, Lowestoft, Great
Grimsby, Plymouth, Wisbeach, Southampton, &c., have been built with
creosoted timber, and in no case have the _Teredo navalis_, _Limnoria
terebrans_, or any other marine worms or insects been found to attack
these works, as certified to by the engineers in whose charge the several
works are placed. In the cases of Lowestoft and Southampton we are
enabled to give the detailed reports.
A most searching examination, lasting many days, was made in 1849, upon
every pile in Lowestoft Harbour, by direction of Mr. Bidder; and the
report of Mr. Makinson, the Superintendent of Lowestoft Harbour Works,
contains the subjoined statement:
“The following is the result, after a close and minute investigation of
all the piles in the North and South Piers.
“_North Pier._--The whole of the creosoted piles in the North Pier, both
seaward and inside the harbour, nine hundred in number, are sound, and
quite free from _teredo_ and _limnoria_.
“_South Pier._--The whole of the creosoted piles in the South Pier, both
seaward and inside the harbour, seven hundred in number, are sound, and
quite free from _teredo_ and _limnoria_.
“There is no instance whatever of an uncreosoted pile being sound. They
are all attacked, both by the _limnoria_ and the _teredo_, to a very
great extent, and the piles in some instances are eaten through. All the
creosoted piles are quite sound, being neither touched by the _teredo_ or
the _limnoria_, though covered with vegetation, which generally attracts
the _teredo_.”
There was only one instance of a piece of creosoted wood, in Lowestoft
Harbour, being touched by a worm, and that was occasioned by the workmen
having cut away a great part of one of the cross heads, leaving exposed
the interior or heart of the wood, to which the creosote had not
penetrated. At this spot a worm entered, and bored to the right, where
it found creosote; on turning back and boring to the left, but finding
creosote all around, its progress was stopped, and it then appeared to
have left the piece of wood altogether.
In 1849, Mr. Doswell, who had the conduct of experiments on different
descriptions of wood at Southampton, where the river was so full of the
worm that piles of 14 inches square had been eaten down to 4 inches in
four years, reported as follows: “From my examination, last spring tides,
of the specimen blocks attached, on the 22nd February, 1848, to some
worm-eaten piles of the Royal Pier, I am enabled to report that Bethell’s
creosoted timbers all continue to be unaffected by the worms; that the
pieces saturated with Payne’s solution continue to lose in substance by
their ravages; and that the unprepared timbers diminish very fast, except
the American elm, which stands as well (or nearly so) as that prepared by
‘Payne’s solution.’”
The following are the detailed particulars:
BETHELL’S CREOSOTED BLOCKS, PLACED FEBRUARY 22, 1848.
Memel, at low water of spring tides } Unaffected by worms.
Red pine, at low water of neap tides }
Yellow fir, at high water of neap tides A few barnacles.
PAYNIZED BLOCKS, PLACED APRIL 6, 1848.
Red pine, at low water of spring tides Worm-eaten.
American elm, at low water of neap tides } A few barnacles.
Fir, at high water of neap tides }
UNPREPARED BLOCKS, PLACED APRIL 6, 1848.
Memel, at low water of spring tides Much worm-eaten.
American elm, at low water of neap tides A few barnacles.
Fir, at high water of neap tides Much worm-eaten.
On 1st January, 1852, Mr. Doswell ascertained that, notwithstanding the
number of _teredines_ and _limnoria_ to be found in the Southampton
Waters, none of the creosoted blocks had been attacked by them.
According to M. Forestier, similar results have been obtained at
Brighton, Sunderland, and Teignmouth.
Allusion has already been made to Mr. Pritchard, of Shoreham, with
reference to preserving timber. On July 26, 1842, he presented a report
to the Treasurer of the Brighton Suspension Chain Pier Company, upon the
preservation of timber from the action of sea-worms. We give a portion of
it, as follows:
“Stockholm tar has been used, and proved to be of little service; this
tar is objectionable owing to its high price, and also from its being
manufactured from vegetable substances. All tars containing vegetable
productions must be detrimental to the preservation of timber, especially
when used in, and exposed to, salt water. This tar does not penetrate
into the wood, and in a very few months the salt acid of the sea will eat
it all away.
“Common gas or coal tar has been used to a great extent, and its effects
are apparent to all. It does a very great deal of harm, forms a hard or
brittle crust or coat on the wood, and completely excludes the damp and
unnatural heat from the possibility of escape, owing to its containing
ammonia, which burns the timber, and in a few years it turns brown
and crumbles into dust. Indeed, timber prepared with this tar will be
completely destroyed on this coast and pier by the ravages of the _Teredo
navalis_, and the _Limnoria terebrans_, in five or six years.
“Also Kyan’s patent, or the bi-chloride of mercury, has been used, but
has proved equally useless. The sleepers Kyanized five years ago, and
in use at the West India Dock warehouses, have been discovered to decay
rapidly, and the wooden tanks at the Anti-Dry-Rot Company’s principal
yard are destroyed.
“I would recommend you for the future to use ‘oil of tar and pyrolignite
of iron’ (Bethell’s patent). This process will, without a doubt, succeed.
I have proved in hydraulic works on this coast that it will fully prevent
the decay in timber piles, destroy sea-worms, and supersede the necessity
of coating the piles with iron nails. In Shoreham Harbour, for instance,
there is a piece of red pine accidentally infused with pyrolignite of
iron, which after being in use twelve years is perfectly sound. There is
another waleing piece, the very heart of English oak, Kyanized, and in
use only four years, which is like a honeycomb or network, completely
eaten away by the _teredo_ and other sea-worms. I have fully proved the
efficiency of this method at different harbours and docks. Sixteen years
ago I had timber prepared with it, and in use on the shores of the Dee,
and it is at the present moment perfectly sound. The pyrolignite of iron
must be used of very pure quality; the timber must be dry; afterwards
the oil of tar must be applied, and not on any account must it contain a
particle of ammonia. The immense destruction on the coast of timber by
the sea-worms, and the important fact that at the Chain Pier there are
not twenty of the original piles remaining at the present time, is of
itself sufficient to awaken anxiety.”
With regard to the opinion of foreigners on the subject of creosoting,
we cannot do better than quote the report of the commission or committee
(instituted in 1859) of the Royal Academy of Sciences, Holland, upon the
means of preserving wood from the _teredo_, published at Haarlem in
1866. It is as follows:
“To conclude, it results from experiments which the committee has
directed during six consecutive years, that--
“1st. Coatings of any sort whatever applied to the surface of the timber
in order to cover it with an envelop upon which the young _teredo_ will
not fasten offer a very insufficient protection; such an envelop soon
becomes damaged, either by mechanical action, such as the friction of
water or ice, or by the dissolving action of water; and as soon as any
point upon the surface of the wood is uncovered, however small it be, the
_teredoes_ of microscopic size penetrate into the interior of the wood.
“Covering wood with plates of copper, or zinc, or flatheaded nails are
expensive processes, and only defend the wood as long as they present a
perfect and unbroken surface.
“2nd. Impregnation with soluble metallic salts generally considered
poisonous to animals does not preserve the wood from the invasions of
the _teredo_; the failure of these salts is partly attributable to their
being soaked out of the wood by the dissolving action of the sea-water,
partly also to the fact that some of these salts do not appear to be
poisonous to the _teredo_.
“3rd. Although we cannot venture to say that there may not be found in
the colonies a wood that may resist the _teredo_, yet we may affirm that
hardness of any timber is not an obstacle to the perforations of this
mollusc. This has been proved by the ravages it has made on the Gaïac and
Mamberklak woods.
“4th. The only means which can be confidently regarded as a preservative
against the ravages of the _teredo_ is the creosote oil; nevertheless,
in the employment of this agent great care should be taken regarding the
quality of the oil, the degree of penetration, and the quality of the
wood treated.”
These results of the experiments of the committee are confirmed by the
experience of a large number of engineers of ponts et chaussées (bridges
and causeways) in Holland, England, France, and Belgium. For example,
very lately a Belgian engineer, M. Crepin, expressed himself as follows
in his Report, dated 5th February, 1864, upon experiments made at Ostend:
“The experiment now appears to us decisive, and we think we may conclude
that fir timber well prepared with creosote oil of good quality is proof
against the _teredo_, and certain to last for a long time. Everything
depends, therefore, upon a good preparation with good creosote oil, and
on the use of wood capable of injection. It appears that resinous wood is
easiest to impregnate, and that white fir should be rejected.”
M. Forestier, the able French engineer at Napoléon-Vendée sums up as
follows the results of the experiments undertaken by him in the port of
Sables-d’Olonne, viz.:
“These results fully confirm those obtained at Ostend, and it appears
to us difficult not to admit that the experiments of Ostend and Sables
d’Olonne are decisive, and prove in an incontestable manner that the
_teredo_ cannot attack wood properly creosoted.”
It thus appears that there are three preservative methods, which,
according to experience, will save timber piles from the ravages of the
worms, viz.: 1st. By using woods able to resist unaided their attacks.
2nd. The mechanical method, which is, by covering the piles with scupper
nails, &c. This process is, however, very expensive, especially as the
four sides of the pile must be covered; and, moreover, it affords no
protection to the timber from internal rot or decay. 3rd. The chemical,
or “creosoting” method. This process is cheaper than the last; it
preserves the wood from decay, and no worms will touch it.
When unprepared piles are placed in the sea, there is every probability,
sooner or later, of their being attacked by the _teredo_. This animal,
however, is not left in peaceable enjoyment of the dwelling which it has
constructed, and the food which it loves, but is liable to be attacked
by an enemy, an _annelide_, to which the late M. de Haan has given
the name of _Lycoris fucata_. This animal is to be found wherever the
_teredo_ exists, indeed its eggs and larva are to be met with in the
midst of those of the mollusc. M. Kater has remarked that the adult
_lycoris_ dwelling in the mud which it enters during winter, and into
which the piles are driven, climbs up the pile to the hole formed by the
_teredo_, where, in some manner, it sucks or eats its victim; then having
enlarged the entrance to the hole, it enters and rests in the place of
the _teredo_. After a time it goes back to the entrance, and commences to
seek for fresh prey.
The _lycoris_ is narrow and not very long, provided laterally with a
great many little feet terminating in points and covered with hair, and
having in front a pair of hard superior jaws, pointed horns, and the
inferior jaws bent round in the form of hooks. Behind the head are four
pairs of tubuliform gills. It is with these arms that this little animal
pursues and devours the _teredo_.
One day M. Kater was fortunately able to observe the operations of the
_lycoris_, One of these animals coming out of a hole in the wood which
he inhabited, seized upon a _teredo_, which M. Kater had previously
deposited at the bottom of the vessel containing the wood. He saw the
_annelide_ seize the _teredo_, hurry away with it to the hole which he
occupied, and so completely devour it that he finally left only the two
valves of the shell. Our illustrations of the _teredo_ and _lycoris_
are derived from the works of Mr. Paton and M. Forestier; and our own
sketches.
If the _lycoris_ would only destroy the _teredo_, when the mollusc was in
its infancy, what an invaluable little annelide it would be!
It appears to us a great pity that the woods we have named, or some of
them, are not brought over to England in large quantities for harbour
works. In Ceylon and India, the trees are felled by Indian wood-cutters
at little cost; they are then dragged to the river banks by elephants
or buffaloes, to be floated down the rivers to the different ports, so
that labour is cheap. The question then remains, how to get the woods
to England? When the ‘Great Eastern ship has finished carrying cables,
perhaps its owners will not object to send the ship on a few voyages
with heavy cargoes to India, Demerara, &c., bringing home “teredo-proof
woods,” _at moderate charges for freight_?
Finally, to place the subject in a practical form, we think the
Institute of Civil Engineers, of London, would be heartily thanked by
the engineering world if they would appoint a committee to inquire into
the damages done to works by sea-worms; why they are found in some parts
of a roadstead or harbour, and not in others; to consider the different
remedies which have been proposed, their cost, and method of application;
what course should be adopted to prevent sea-water injuriously affecting
iron piles; and lastly, to publish a detailed account of their
experiments and recommendations.
CHAPTER VIII.
ON THE DESTRUCTION OF WOODWORK IN HOT CLIMATES BY THE TERMITE OR WHITE
ANT, WOOD-CUTTER, CARPENTER BEE, &c., AND THE MEANS OF PREVENTING THE
SAME.
Of the ant proper, or that belonging to the order _Hymenoptera_, there
are three species[24] in particular which attack timber, viz.:
1st. _Formica fuliginosa_, or black carpenter ant, which selects hard and
tough woods.
2nd. _Formica fusca_, or dusky ant, which prefers soft woods.
3rd. _Formica flava_, or yellow ant, which also prefers soft woods.
The carpenter bee prefers particular kinds of wood. In India it is very
fond of cadukai (_Tamil_) wood, which is often used for railway sleepers.
Round the holes it makes there is a black tinge, arising, probably, from
the iron in its saliva acting on the gallic acid of the timber. Providing
it meets with the wood it prefers, it is not very particular whether it
is standing timber, or the beams of a residence.
The termite, or white ant, is a terrible destroyer of wood in nearly
all tropical countries. There are many species of termite, and all are
fearfully destructive, being indeed the greatest pest of the country
wherein they reside. Nothing, unless cased in metal, can resist their
jaws; and they have been known to destroy the whole woodwork of a house
in a single season. They always work in darkness, and, at all expenditure
of labour, keep themselves under cover, so that their destructive labours
are often completed before the least intimation has been given. For
example, the termites will bore through the boards of a floor, drive
their tunnels up the legs of the tables or chairs, and consume everything
but a mere shell no thicker than paper, and yet leave everything
apparently in a perfect condition. Many a person has only learned the
real state of his furniture by finding a chair crumble into dust as he
sat upon it, or a whole staircase fall to pieces as soon as a foot was
set upon it. In some cases the termite lines its galleries with clay,
which soon becomes as hard as stone, and thereby produces very remarkable
architectural changes. For example, it has been found that a row of
wooden columns in front of a house have been converted into a substance
as hard as stone by these insects. In pulling down the old cathedral _at
Jamaica_, some of the timbers of the roof, which were of hard wood, were
eaten away, and a cartload of nests formed by the ants was removed, after
being cut away by great labour with hatchets.
The first indication of a house being attacked by ants in the tropics
is, perhaps, the yielding of a floor board in the middle of a room, or
the top hinge of a door suddenly leaving the frame to which it had been
firmly screwed a short time before.
That the ants provide for winter--as not only Dr. Bancroft and many
others, even King Solomon, reports--is found to be an error. Where there
is an ordinary winter, the ants lie dormant, during which torpid state
they do not want food.
The greater number of species belong to the tropical regions, where they
are useful in destroying the fallen trees that are so plentiful in those
latitudes, and which, unless speedily removed, might be injurious to the
young saplings by which they are replaced. Two species, however, are
known in Europe, namely, _Termes lucifugus_ and _Termes rucifollis_, and
have fully carried out their destructive character, the former species
devouring oaks and firs, and the latter preferring olives and similar
trees. _At La Rochelle_ these insects have multiplied so greatly as to
demand the public attention.
M. de Quatrefages, who visited one of the spots in which these
destructive insects had settled themselves, gives the following account
of their devastating energy: “The prefecture and a few neighbouring
houses are the principal scene of the destructive ravages of the
termites, but here they have taken complete possession of the premises.
In the garden not a stake can be put into the ground, and not a plank
can be left on the beds, without being attacked within twenty-four or
forty-eight hours. The fences put round the young trees are gnawed from
the bottom, while the trees themselves are gutted to the very branches.
“Within the building itself the apartments and offices are all alike
invaded. I saw upon the roof of a bedroom that had been lately repaired
galleries made by the termites which looked like stalactites, and
which had begun to show themselves the very day after the workmen left
the place. In the cellars I found similar galleries, which were either
half way between the ceiling and the floor, or running along the walls
and extending, no doubt, up to the very garrets, for on the principal
staircase other galleries were observed, between the ground floor and
the second floor, passing under the plaster wherever it was sufficiently
thick for the purpose, and only coming to view at different points where
the stones were on the surface, for, like other species, the termites of
La Rochelle always work under cover wherever it is possible for them to
do so. It is generally only by incessant vigilance that we can trace the
course of their devastations and prevent their ravages.
“At the time of M. Audoin’s visit a curious proof was accidentally
obtained of the mischief which this insect silently accomplishes. One
day it was discovered that the archives of the department were almost
totally destroyed, and that without the slightest external trace of any
damage. The termites had reached the boxes in which these documents were
preserved by mining the wainscoting, and they had then leisurely set to
work to devour these administrative records, carefully respecting the
upper sheets and the margin of each leaf, so that a box which was only
filled by a mass of rubbish seemed to enclose a file of papers in perfect
order.
“The hardest woods are attacked in the same manner. I saw on one of the
staircases an oak post, in which one of the clerks had buried his hand
up to the wrist in grasping at it for support, as his foot accidentally
slipped. The interior of the post was entirely formed of empty cells, the
substance of which could be scraped away like dust, while the layer that
had been left untouched by the termites was not thicker than a sheet of
paper.”
It is most probable that these insects had been imported from some
vessel, as they attacked two opposite ends of the same town, the centre
being untouched. M. de Quatrefages tried many experiments on these
insects with a view of discovering some method of destroying them, and
came to the conclusion that if _chlorine_ could be injected in sufficient
quantities, it would in time have the desired result.
The termite or white ant is represented by Linnæus as the greatest pest
of both Indies, because of the havoc they make in all buildings of wood,
in utensils, and in furniture. They frequently construct nests within
the roofs and other parts of houses, which they destroy if not speedily
extirpated. The larger species enter under the foundations of houses,
making their way through the floors and up the posts of buildings,
destroying all before them; and so little is seen of their operations
that a well-painted building is sometimes found to be a mere shell, so
thin that the woodwork may be punched through with the point of the
finger.
Many kinds of wood _in Brazil_[25] are impervious to the termite, which
insect generally selects the more porous woods, and especially if
these are in contact with the earth. In dry places, and with _a free
circulation of air_, it does not prefer timber thus situated; and it is
found that roofs of buildings of _good_ and well-seasoned native wood
resist for an indefinite period both the climate and the termite. As a
general rule, Brazilian timber is very brittle.
It shows the difference of effects between one climate and another, that
in Brazil the more porous and open-grained timbers are most subject to
the attacks of the white ant, especially if they are in contact with the
earth; but _in Australia_ it is the reverse, for there it is the hardest
description of timber that those insects first attack. There is one wood
in particular, in common use, to which this remark applies, namely, “Iron
Bark.” Its density is so great that it sinks in water, and its strength
is extraordinary, and yet the wood the white ants are particularly fond
of. In the West Indies, the ants prefer hard woods.
_At Bahia_, the timber is less affected by the termite than _in
Pernambuco_; but even in the latter place the white ant does not like dry
places with a free circulation of air.
Mr. Shields, when on a short visit to Pernambuco, examined some timber
bridges, and in one, which had only been constructed three years, he
found the ends of the timber had been placed in contact with the moist
clay; at those places he could readily knock off the crust of the wood,
and the interior of the wood was almost filled with white ants: the
decay was augmented by the contact of the wood with the moist clay.
We have been informed that timber for the Government works is stored
to the depth of about 1 foot 6 inches in the sea-sand, to protect it
from the white ants and the _teredo_; and that in Pernambuco, since the
establishment of the gas-works, the Brazilian engineers and constructors
“pay” over the ends of all timbers used in buildings with coal-tar.
_In Ceylon_, no timber--except ebony and ironwood, which are too hard;
palmyra, in _northern_ Ceylon; and those which are strongly impregnated
with camphor or aromatic oils, which they dislike--presents any obstacle
to their ingress. Sir Emerson Tennant, in his work on Ceylon, says: “I
have had a cask of wine filled, in the course of two days, with almost
solid clay, and only discovered the presence of the white ants by the
bursting of the corks. I have had a portmanteau in my tent so peopled
with them in the course of a single night that the contents were found
worthless in the morning. In an incredibly short time a detachment of
these pests will destroy a press full of records, reducing the paper to
fragments; and a shelf of books will be tunnelled into a gallery, if it
happened to be in their line of march.”
In Ceylon, the huts are plastered over with earth, which has been thrown
up by white ants, after being mixed with a powerful binding substance
(produced by the ants themselves), and through which the rain and
moisture cannot penetrate. This will hold the walls together when the
entire framework and the wattles have been eaten, or have become decayed.
_In the Philippine Islands_, ambogues, a strong, durable wood, suffers
much from the termites. Sir John Bowring, in his work on these islands,
thus writes of the ravages of the white ants in the town of Obando,
Province of Bulacan, Philippine Islands: “It appears that on the 18th
March, 1838, the various objects destined for the services of the
mass, such as robes, albs, amices, the garments of the priests, &c.,
were examined, and placed in a trunk made of the wood called ‘narra’
(_Pterocarpus palidus_). On the 19th they were used in the divine
services, and in the evening were restored to the box. On the 20th some
dirt was observed near it, and, on opening it, every fragment of the
vestments and ornaments of every sort were found to have been reduced to
dust, except the gold and silver lace, which were tarnished with a filthy
deposit. On a thorough examination not an ant was found in any other
part of the church, nor any vestige of the presence of these voracious
destroyers; but five days afterwards they were discovered to have
penetrated through a beam 6 inches thick.”
The red ant _in Batavia_ (north-west end of Java) is another devastator.
The red ant contains formic acid (acid of ants) and a peculiar resinous
oil. Thunberg[26] has found cajeput effectual in destroying the red ants
of Batavia: he used it to preserve his boxes of specimens from them. When
ants were placed in a box anointed with this oil, they died in a few
minutes.
_In Surinam_, Guiana, several species of worms are produced in the
palm-trees as soon as they commence to rot: they are called “groo-groo,”
and are produced from the spawn of a black beetle; they are very fat,
and grow to the size of a man’s thumb. The groo-groo will very quickly
destroy wood which has commenced to rot.
_In Surinam_, Captain Stedman[27] was obliged to drive nails into the
ceiling of his room, and hang his provisions from the nails; he then made
a ring of dry chalk around them, very thick, which crumbled down the
moment the ants attempted to pass it. In Guiana, the young ants will swim
across a small pool of water to get at sugar; some get drowned, the rest
get the sugar.
_In Japan_, according to Kœmpfer,[28] ants do considerable damage to wood.
_In Senegal_, the ant (_Termite belliqueux_) is a formidable agent of
destruction. In a season, all the carpentry of a house is destroyed by
them. Spartimann, in his ‘Voyage to the Cape of Good Hope,’[29] gives an
excellent account of their methods of working.
The _Termite lucifuge_ has been discovered in the environs of _Bordeaux_,
in the pine-trees; also in the marine workshops at _Rochefort_. It is
believed to have been imported from America.
The _Termite flavicole_, a few years since, attacked the olive-trees of
_Spain_, and it occasionally visits the centre of _France_.
White or yellow pine wood can only be used in the tropics for doors,
movable window frames, bodies of railway waggons, or other work intended
to be kept in motion. Its use even for these purposes is questionable, as
the white ant has such an affinity for it, that a door or a window which
has remained shut for a few weeks will almost invariably be attacked by
that insect.
North American pitch pine withstands very well the attacks of the
termite, when used in the roofs of buildings, or in any locality not
humid; but it is found after a time, when laid upon the earth, to lose
its resisting powers, as well as to become subject to rapid decay.
“Greenheart” timber in its natural state is proof against the attacks
of this insect in tropical climates--especially that known as the
“purple-heart” wood. There are two reasons why it enjoys this immunity
from attack: first, there is its great hardness; and, secondly, there
is the presence of a large quantity of essential oil. It is very hard
and durable wood; a little heavier than water. It is obtained at
Demerara.[30] Great care is required in working it, as it is very liable
to split. In sawing it is necessary to have all the logs bound tightly
with chains, failing which precaution the log would break up into
splinters, and be very apt to injure the men working it.
“Jarrah” wood, from Australia, is also proof against the attacks of the
white ant. It is occasionally liable to shakes.
“Panao” wood, from the Philippine Islands, gives the talay oil, which
destroys insects in wood.
“Bilian” wood is imported to Bombay, from Sarawak, Borneo. This wood is
impervious to the attacks of the termite, and does not decay when under
fresh or salt water, where it remains as hard as stone.
“Sál” wood, in India, is occasionally touched by the white ant. This
wood, however, requires two years to season, and it will twist, shrink,
and warp whenever the surface is removed, after many years’ seasoning.
Only about 2 lb. of creosote oil per cubic foot can be injected into
sál wood. “Kara-mardá” is avoided by this little insect; but when used
for planks it requires twelve to fifteen months’ previous seasoning.
“Neem-wood,” used for making carved images, enables an image to remain
undisturbed by the white ant.
The following is a list of woods which resist for a long time, if not
altogether, the attacks of the termites, or white ants:
ANT-RESISTING WOODS.
_America._--Butternut, pitch pine. (Pitch pine is sometimes
attacked.)
_Australia, Western._--Jarrah.
_Borneo._--Bilian.
_Brazil._--The sicupira assú, sicupira meirim, or verdadeiro,
sicupira acari, oiticira, gararoba, paó saulo, sapucaia de Pilao,
sapucarana, paó ferro, and imberiba, resist the white ant,
_except_ in the sapwood. The angelim amargozo, araroba, pitia,
cocâo, bordâo de Velha, ameira de Sertao, parohiba, cedro, louro
cheiroso, and louro ti, resist the white ant, _even_ in the
sapwood.
_Ceylon._--Ebony, ironwood, palmyra, jack, gal-mendora, paloo,
cohambe.
_Demerara._--Greenheart.
_Guiana, British._--Determa, cabacalli, kakatilly.
_India._--Cedar, sál, neem, kara mardá, sandal, erul, nux vomica,
thetgan, teak. (Ants will bore through teak to get at yellow
pine.)
_Indies, West._--Bullet wood, lignum vitæ, quassia wood.
_Pernambuco (Brazil)._--Maçaranduba (red), barubú (purple),
mangabevia de Viado.
_Philippine Islands._--Molave, panao.
_Tasmania._--Huon pine.
_Trinidad._--Sepe.
In piles of wooden sleepers which have been lying ready for use _in
India_ for about six months, at least 10 per cent. have been found
destroyed by ants. It has been supposed that the jarring motion of a
train on a railway would prevent the white ant from destroying the timber
sleepers; but there is reason to doubt this, from the fact that on an
examination of the ‘Hindostan’ steam vessel, a considerable portion
of her timber framing was found to be eaten away by that destructive
insect, particularly in the parts close to the engine and boilers, where
there had been the greatest amount of vibration. The telegraph posts are
particularly subject to their depredations so long as the timber is sunk
in the ground; but when a metallic socket is supplied, the wood is safe
from their visits. A further precaution is taken to preserve the lower
end of the post by running liquid dammer into the metallic sheath, so
that the enclosed part of the post is encased with a coating of resin.
The telegraph wires when covered with guttapercha (a vegetable substance)
are also liable to their attacks.
Numerous expedients have been suggested for getting rid of this
destructive insect, some of which have been successful, but the majority
only partially so.
In India, the timbers of a house infested with white ants are
periodically beaten to drive them away. Of course, this only succeeds for
a short time, as they soon return.
The salt vessels plying on the coast of India use oil of tar, and a
considerable quantity of castor-oil, mixed with cow-dung mortar, which,
while it adheres to the wood, is an effectual protection against ants
and rot. The earth oil, or Arracan oil, is considered as good as creosote
to protect wood from ants. It can be obtained at Moulmein and Rangoon, in
leathern bottles or skins, at about 6_d._ per gallon.
It used to be a practice _in the West Indies_ to destroy whole colonies
of ants which had built their nests either on trees or under the roofs of
houses, by shooting powdered arsenic out of a quill into an orifice made
into their covered ways, along which they ascended and descended from and
to the ground.
It has been estimated that the depredations of the white ant in India
costs the Indian Government 100,000_l._ a year, which is expended in
repairing the woodwork of houses, barracks, bridges, &c.
When Dr. Boucherie gave up his sulphate of copper process for the use
of the French public, he received _a national reward_. If the Indian
Government is disposed to give us _a national reward_, we could show how
it may save at least half the 100,000_l._ a year--which is expended in
repairing the damages done by the white ants--with little trouble.
In the Madras Presidency periodical inspections have to be made, not
only with regard to the white ant, but with respect to the presence and
subsequent germination of vegetable matter or seeds in the mortar. In
some instances, where proper precautions had not been taken, roots had
formed very rapidly, and of such great size as to bodily dislodge by
their pressure large stones from buildings. Therefore, to prevent this
germination, a proportion of “Jagherry,” or coarse native sugar, varying
from 2 per cent. in ordinary work, to from 5 per cent. to 8 per cent. in
arch work, is mixed with the lime.
In 1856, in consequence of the ravages of the white ants in the King’s
Magazine, Fort William, India, the flooring and powder racks had to
be reinstated. Captain A. Fraser, R.E., had the basement covered with
concrete, 4 lb. of yellow arsenic being added to every 100 cubic feet
of concrete. In the mortar used for the pillars arsenic was used in
the proportion of ½ lb. to every 100 cubic feet of brickwork; a small
quantity of arsenic was also mixed with the paint, and ½ lb. (four
chittacks) of arsenic was also mixed with every 100 superficial feet of
plaster. In 1859 the town mayor reported to the Government that no traces
of white ants had since been found either inside or outside the building.
Colonel Scott, when Acting Chief Engineer, Madras Presidency, reported to
the Government, December 24, 1858, that the following receipt was used
for exterminating white ants in the Madras Presidency, and was found to
be very successful:
lb. oz.
Arsenic 2 4
Aloes 2 4
Chunam soap 2 13 (common country soap).
Dhobies mud 2 8 (Khar).
Pound the arsenic and aloes, scrape the soap, mix with mud, and boil in a
large chatty half full of water until it bubbles; let it cool, and when
cold, fill up with cold water. The mixture should boil for nearly an
hour: it is applied as a wash.
The white ants of Calcutta are small in comparison with those of the
upper provinces.
Colonel Scott, Chief Engineer at Bombay, records instances of timber
being boiled under pressure in various antiseptic solutions, such as
sulphate of copper, arsenious acid, and corrosive sublimate, with
satisfactory results; but considerable apparatus is necessary, and the
expense forbids its use except in large public works. On the other hand,
in 1847, Mr. G. Jackson, being engaged under Mr. Rendel, C.E., on works
in India, tried several experiments with Mr. J. Bourne, in order to
test the possibility of preserving timber from the ravages of the white
ant. Ninety pieces of wood, 9 inches long by 4 inches square, saturated
according to the different processes of Burnet, Payne, and Margary,[31]
under the direction of the patentees themselves, were experimented upon,
in five situations, one with a considerable amount of moisture, and four
dry; through inadvertency Mr. Bethell’s specimens were only tested in the
dry positions. The result was, that where there was moisture the timber
was entirely destroyed, whilst where they were kept dry the result was
better, but still not satisfactory. It seems difficult to account for
these different results obtained by Colonel Scott and Mr. Jackson; but
evidently the same strength of solutions, and the same qualities and
descriptions of woods, cannot have been used by each gentleman.
Captain Mann and Captain McPherson painted the joists and planking of
several buildings at Singapore with _gambir composition_, and the result
was perfect success, although the buildings had been previously infested
with white ants. Gutta gambir is juice extracted from the leaves of
a plant of the same name (_Uncaria gambir_) growing in Sumatra, &c.,
inspissated by decoction, strained, suffered to cool and harden, and then
cut into cakes of different sizes, or formed into balls. Chief places
of manufacture, Siak, Malacca, and Bittany; gambir is now imported to
England to a slight extent. The gambir composition referred to is made
as follows: Dissolve three pints of gambir in twelve pints of dammer-oil
over a slow fire; then stir one part of lime, sprinkling it over the top
to prevent its coagulating and settling in a mass at the bottom; it must
be well and quickly stirred. It should then be taken out of the cauldron,
and ground down like paint on a muller till it is smooth, and afterwards
returned to the pot and heated. A little oil should be added to make
it tractable, and the composition can then be laid over the material.
To be treated with a common brush. Against the _Teredo navalis_ may be
substituted the same proportion of black varnish or tar for dammer-oil,
of course omitting the grinding down, which would not answer with tar.
Burnett’s chloride of zinc process is said to be a good preservative for
wood liable to be attacked by ants: the zinc penetrates to the heart of
the wood.
Creosoted timber, it is well known, resists the attacks of the white
ants; but the close grain of the generality of tropical timber renders
any attempt to creosote it all but useless. Of course, creosoted fir
timber could be, in fact is, exported from England, but the cost of
freight and other charges will always make it very expensive, and be a
great drawback to its general use abroad. Mr. J. C. Mellis, Engineer to
the Government of St. Helena, writes in very high terms of creosoted
timber as used there, where the white ant abounds. Between the years 1863
and 1866, experiments[32] were made with many specimens of woods (by
order of the Lieutenant-Governor), in order to find out those which would
resist the white ant. Teak remained uninjured; jarrah wood was partially
destroyed; while pitch-pine, oak, cedar, ash, elm, birch, beech, and
mahogany, were quite destroyed.
In Ceylon creosoted timber is not attacked by white ants, but the black
coating, if exposed, renders it so heat-absorbing, that it is apt to
split, and, unless thoroughly impregnated with the creosote, a road is
opened to the inside, and the ants will soon destroy all that part which
is unprotected.
Coal-tar will destroy white ants. Some years ago Mr. Shields took short
baulks of timber where the ants had commenced operations, and tried the
system of pouring a very small stream of coal-tar through the heart of
the timber which the ants had hollowed out, and afterwards splitting it
open to see the result. He found the white ants completely destroyed;
they were shrivelled up like shreds of half-burnt paper by the mere
effluvium of the coal-tar.
Creosoting is excellent for railway sleepers, piles, &c., but it will not
do for buildings, which the white ants prefer. It is objectionable for
dwellings; 1st, on account of its smell, which is disagreeable; 2nd, on
account of its colour, black, which is unsightly; 3rd, on account of its
inflammability.
With regard to the depredations of white ants, anything of a bitter taste
injected into the fibre of the wood prevents their attacks, though it may
not be so good as coal-tar; even a small quantity of turpentine has the
effect of killing them instantly. Carbolic acid has been used, but its
smell is objectionable. In South America, the leaves of the black walnut
are soaked in water for some hours, then boiled; and when the liquid
has cooled, it is applied to the skins of horses and other animals, to
prevent their being bitten or “worried” by insects. We do not know if
this has been used as a wash, or injected into wood, to prevent it being
“worried” by ants.
It thus appears that there is no remedy generally adopted in tropical
climates for preventing the depredations of the white ants; but there is
one method very frequently adopted in hot countries of getting rid of
them. It is a desperate remedy, we admit, but desperate cases frequently
require desperate remedies: it is simply by EATING THEM. Europeans have
pronounced the termites to be peculiarly delicate and well flavoured,
something like sweetened cream. The termites are prepared for the table
by various methods, some persons pounding them so as to form them
into a kind of soft paste, while others roast them like coffee-beans
or chestnuts. Termites, or white ants, are eaten by various African
tribes, both raw and boiled; and it is said that the Hottentots “get
into good condition on this diet.” In India, the natives capture great
quantities of these insects, which they mix up with flour, producing a
kind of pastry, which is purchased at a cheap rate by the poorer classes.
In Ceylon, bears feed on the termites. Some of the Africans prepare
large quantities of them for food, by parching them in kettles over a
slow fire; in this condition they were eaten by handfuls as delicious
food. The traveller Smeathman states that he often ate them dressed in
this way, and found them to be “delicate, nourishing, and wholesome,
resembling in flavour sugared cream, or sweet-almond paste.” In Brazil,
the yellow ants are eaten by many persons. Humboldt states that in some
of the South American countries ants are mixed with resin and eaten as
a sauce. In Siam, ants’ eggs are considered a luxury; they are sent to
the table curried, or rolled in green leaves mingled with fine slices
or shreds of fat pork. In Sweden, ants are distilled along with rye to
give a flavour to the inferior kinds of brandy. Chemists have ascertained
that ants secrete a pleasant kind of vinegar, or a peculiar acid, called
formic acid.
In Brazil, however, the eating process goes on extensively as follows:
1st. Ants eat the wood.
2nd. Ant-eaters eat the ants.
3rd. Woodsmen eat the ant-eaters.
4th. Wild animals eat the woodsmen.
Teak-oil, extracted from teak chips, was, in 1857, recommended by a
Mr. Brown to the Government of St. Helena, through the Government of
Madras. Timber coated with this oil, as reported to the Secretary to the
Government of Madras by the several executive engineers of the Public
Works Department, even when placed in a nest of white ants, was not
touched by them. The cost of this oil, in certain experiments made by
order of the Madras Government, in 1866, was reported to be 6¾ annas for
1¼ ounce, which is too expensive. In the central provinces the cost would
be 1¼ anna per quart.[33]
In the East Indies there are several species of wood-cutter (_Xylocopa_)
and carpenter bee (_Xylocopa_), which confine their ravages to the wood
after it has been felled. The wood-cutter tunnels through the beams and
posts of buildings, which they frequent in great numbers. The passages
are from 12 to 15 inches long, and more than half an inch in diameter. If
the insects are numerous, their ravages are dangerously destructive, and
they soon render beams unsafe for supporting the roof.
The carpenter bee of Southern Africa is one of those curious insects
which construct a series of cells in wood. After completing their
burrow, which is open at each end, they close the bottom with a flooring
of agglutinated sawdust, formed of the morsels bitten off during the
operation of burrowing, lay an egg upon this floor, insert a quantity of
“bee-bread,” made of the pollen of flowers and their juices, and then
cover the whole with a layer of the same substance that was used for
the floor. Upon this is laid another egg, another supply of bee-bread
is inserted, and a fresh layer of sawdust superimposed. Each layer is
therefore the floor of one cell and the ceiling of another, and the
insect makes on the average about ten or twelve of these cells.
The carpenter bee destroys the woodwork of buildings in the north of
Ceylon, but in the south of the island woodwork has two enemies to
contend against, viz. the porcupine and a little beetle. The porcupine
destroys many of the young palm-trees, and the ravages of the cocoa-nut
beetle (_Longicornes_) are painfully familiar to the cocoa-nut planters.
The species of beetle, called by the Singalese “cooroominya,” is very
destructive to timbers. It also makes its way into the stems of the
younger trees, and after perforating them in all directions, it forms
a cocoon of the gnawed wood and sawdust, in which it reposes during
its sleep as a pupa, till the arrival of the period when it emerges as
a perfect beetle. Mr. Capper relates that in passing through several
cocoa-nut plantations, “varying in extent from twenty to fifty acres, and
about two to three years old, and in these I did not discover a single
young tree untouched by the cooroominya.”
[Illustration: _Carpenter Bees “at work”._]
Sir E. Tennant thus writes of the operations of the carpenter bee on
the wooden columns of the Colonial Secretary’s official residence, at
Kandy, Ceylon: “So soon as the day grew warm, these active creatures were
at work perforating the wooden columns which supported the verandah.
They poised themselves on their shining purple wings, as they made the
first lodgment in the wood, enlivening the work with an uninterrupted
hum of delight, which was audible to a considerable distance. When the
excavation had proceeded so far that the insect could descend into it,
the music was suspended, but renewed from time to time, as the little
creature came to the orifice to throw out the chips, to rest, or to enjoy
the fresh air. By degrees a mound of sawdust was formed at the base of
the pillar, consisting of particles abraded by the mandibles of the bee;
and these, when the hollow was completed to the depth of several inches,
were partially replaced in the excavation, after being agglutinated to
form partitions between the eggs, as they are deposited within.”
Fortunately in England the owner of a house has no opportunity
of watching (“with an uninterrupted hum of delight, audible to a
considerable distance”) the operations of the carpenter bee, on the
wooden beams and posts of his building.
We must now _consider the ways_ of the wood-beetle, which will be found
described in the next chapter, and only write a few words before closing
this. A modern engineer is no sluggard, of that we are certain; but if
he intends erecting large buildings in any of the places abroad which we
have referred to, he will find it very necessary to pay particular notice
of the following words of King Solomon:
“Go to the ant, thou sluggard; _consider her ways_, and be wise.”
Proverbs vi. 6.
CHAPTER IX.
ON THE CAUSES OF DECAY IN FURNITURE, WOOD CARVINGS, ETC., AND THE MEANS
OF PREVENTING AND REMEDYING THE EFFECT OF SUCH DECAY.
Although trunks and boxes are of themselves of little importance, they
derive great consequence from the valuable deposits of written papers,
deeds, books, &c., which they frequently contain, that are subject to
destruction from timber-destroying insects. It is well known that the
smell of Russian leather, which arises from an essential oil, is a
preservative of books. Leather or woods impregnated with petroleum, or
with oil of coal-tar (which has a smell not much dissimilar) would be
productive of the same effect, because known to be peculiarly obnoxious
to insects: these oils are, however, very inflammable.
At all times beech-wood is exposed to the attacks of beetles, and it
cannot be used, even for household furniture, without being impregnated
with some kind of oil or varnish, as a defence against these insects--a
very curious fact, for the growing trees are remarkably free from the
attacks of wood-devouring insects. Larch being solid, and its juices hot,
pungent, and bitter, is rarely affected with the larvæ of insects.
Mr. Westwood, Hope Professor of Zoology, Oxford, says: “The insects
which in this country are found to be the most injurious from their
habit of burrowing into the wood of furniture, belong to three species
of beetles, of small size, and cylindrical in form (the better to enable
them to work their way through the burrows in the wood), belonging to
the family _Ptinidæ_, and known under the systematic names of _Ptilinus
pectinicornis_, _Anobium striatum_, and _Anobium tessellatum_.
“In the perfect state, the insects of the genus _Anobium_ are well known
under the name of the “deathwatch,” as these insects produce the ticking
noise occasionally heard in old houses. It is also the _Anobium striatum_
which is so injurious in libraries; the grub burrowing through entire
volumes, and feeding upon the paper, and especially the _pasted_ backs of
the books.
“The destruction of these insects, when enclosed in articles of
furniture, is by no means easy, although with care much mischief might be
prevented. The saturation of the wood with some obnoxious fluid previous
to its being used up in the manufacture of objects of value would be
beneficial.
“A strong infusion of colocynth and quassia, spirits of turpentine,
expressed juice of green walnuts, and pyroligneous acid, have all been
proposed. In hot climates the ravages of the _Anobium_ on books have
been prevented by washing their backs with a fluid compound of corrosive
sublimate (ten grains) and four ounces of alcohol, and the paste used in
the book covers is there also mixed with alcohol.”
Sir H. Davy and Professor Faraday hesitated to employ corrosive sublimate
as a means of preventing the ravages of the bookworm in Earl Spencer’s
library, at Althorp, not feeling certain as to whether the quantity of
mercury used would affect the health of the inhabitants. Amongst all the
combinations of mercury, perhaps the bi-chloride, or corrosive sublimate,
is the most terrible poison. It should be remembered that there are
two chlorides of mercury--one the proto-chloride, ordinarily known as
calomel; the other, bi-chloride, ordinarily known as corrosive sublimate;
the respective compositions of which are as follows:
------------------------------------------------+----------------------
| Parts by Weight.
Calomel, and Corrosive Sublimate. +-----------+----------
| Chlorine. | Mercury.
------------------------------------------------+-----------+----------
Calomel, or proto-chloride of mercury | 36 | 200
Corrosive sublimate, or bi-chloride of mercury | 72 | 200
------------------------------------------------+-----------+----------
Hence the ratio of chlorine in these two chlorides is as one to two.
Botanists have long used a solution of corrosive sublimate in alcohol,
known by the name of Smith’s solution, to preserve the specimens in their
herbaria from the aggressions of insects.
The Rev. J. Wood, writes:[34] “I know to my cost sundry Kaffir articles
being absolutely riddled with the burrows of these tiny beetles (_Anobium
striatum_), and not to be handled without pouring out a shower of yellow
dust, caused by the ravages of the larva. The most complete wreck which
they made was that of a New Guinea bow, which was channelled from end to
end by them, and in many places they had left scarcely anything but a
very thin shell of wood.
“In such cases I have but one remedy, viz. injecting into the holes
spirits of wine in which corrosive sublimate has been dissolved. This is
not so tedious a business as it may seem to be, as the spirit will often
find its way from one hole to another, so that if half a dozen holes
be judiciously selected, the poison will penetrate the whole piece of
wood, kill all the insect inhabitants, and render it for ever impervious
to their attack. The above-mentioned bow cost me but little trouble. I
first shook out the greater part of the yellow powder, and then, placing
the bow perpendicularly, injected the spirit into several holes at the
upper end. The effect was magical. The little beetles came out of the
holes in all directions, and not one survived the touch of the poisoned
spirit; many of them, indeed, dying before they could force themselves
completely out of the holes. The ticking of the deathwatch is, in fact,
the call of the _anobium_ to its mate, and as the insect is always found
in old woods, it is very evident why the deathwatch is always heard in
old houses. There is, by the way, a species of cockroach which acts in a
similar manner, and generally disports itself on board ship, where the
sailors know it by the name of ‘Drummer.’”
The earliest account[35] we can find of the use of corrosive sublimate to
destroy worms in woods is a few words mentioned, in 1705, by M. Homberg,
French Academian. In that year he stated that a person of position in
Provence, France, knew how to make a parquet floor which would resist the
worm, viz. by soaking the wood in water in which corrosive sublimate had
been mixed, and this process he had always found to be very successful.
Herr Temmnick preserved his books from the _anobium_ by dipping them in
a solution of quassia. Except on a small scale, however, the saturation
of furniture seems scarcely practicable. Fumigation seems, however, to be
more available. For small objects, the practice adopted at the Bodleian
Library, Oxford, on Professor Westwood’s recommendation, appears good,
viz. to enclose a number of volumes in a box, shutting quite close, and
placing a small quantity of benzine in a saucer at the bottom of the
case. The same plan might be adopted with small ornamental wood-works,
enclosing them in glass cases shut as nearly air-tight as possible.
The Report of the Commission appointed by the Department of Science
and Art to inquire into the causes of decay in wood carvings, and the
means of preventing and remedying the effects of such decay, which was
published in 1864, states that the action of the worm in wood carvings
may be arrested, and the worm itself destroyed, by vaporization, more
especially by the vapour of benzine; and that, after the worm has been
destroyed, further attacks from it can be prevented by treating the
carved work with a solution of chloride of mercury, either in methylated
spirits of wine, or parchment size, according to the surface character of
the carving or woodwork; the strength of the solution in each case being
60 grains of the chloride of mercury to a pint of fluid, whether spirits
of wine or parchment size. The carving or woodwork should be placed in
a box, made as air-tight as possible, but with means of renewing the
benzine placed in saucers from time to time as it evaporates without
opening the lid of the box. Gilded carved work and panels on which
pictures have been painted, and which have been attacked by the worm, can
only be treated by applying the fumes of the benzine to the back of the
pictures or gilded carved work: there is no reason to suppose that the
vapour of the benzine would influence either the gilding of the one or
the colours of the other.
The process should always be carried out during the spring and early
summer months, according to the state of the temperature and the
observations of those in charge of the carved or other work, as to the
action of the worm, which is manifested by the fine dust falling from the
worm-holes, crevices, &c.
Mr. Henry Crace was engaged in 1855 to restore some of the wood carvings
in the Mercers’ Hall, London, which had been perfectly honeycombed by a
small brown beetle about the size of a pin’s head. The carvings being
first washed, a number of holes were bored in the back by a gimlet, and
also into every projecting piece of fruit and leaves on the face. The
whole was then placed in a long trough, 15 inches deep, and covered with
a solution, prepared in the following manner:--16 gallons of linseed
oil, with 2 lbs. of litharge finely ground, 1 lb. of camphor, and 2 lbs.
of red lead, were boiled, for six hours, being well stirred the whole
time; 6 lbs. of bees’-wax was then dissolved in a gallon of spirits of
turpentine, and the whole mixed while warm thoroughly together.
In this solution the carving remained for twenty-four hours. When taken
out the face was kept downwards, that the oil in the holes might soak
down to the face of the carving. The dust was allowed to remain to form a
substance for the future support of the wood, and as it became saturated
with the oil it increased in bulk, and rendered the carving perfectly
solid.
No insect has since been found to touch these carvings, as they could not
subsist on this composition.
In 1855 the carvings of Grinling Gibbons, at Belton House, were in such
a condition as to render it absolutely necessary that something should
be done to prevent their complete destruction. To this end they were
placed in the hands of Mr. W. G. Rogers, who undertook to experiment upon
their restoration. This gentleman reported that the first step he took
was to have the various pieces photographed, as a means of recording the
position of each detail of the ornamentation, &c. The whole of the works
were in a serious state of decay, portions being completely honeycombed
by the worm. In order to destroy or prevent any future development of
the insect within the wood, Mr. Rogers caused the whole to be saturated
with a strong solution of corrosive sublimate (bi-chloride of mercury)
in water. The colour of the wood, however, suffered so seriously by the
action of the mercury that it was found necessary to adopt some means of
restoring the original tint. (It gives a dark colour to the wood, which
is caused by the metal contained in the sublimate.) This was effected
by ammonia in the first instance, and subsequently by a slight treatment
with muriatic acid. After this the interior of the wood was injected
with vegetable gum and gelatine, in order to fill up the worm-holes and
strengthen the fabric of the carvings. A varnish of resin, dissolved
in spirits of wine, was afterwards spread on the surface, and then the
dismembered pieces were put together in conformity with the photographs
taken, as records, prior to the work of restoration having been commenced.
In order to ascertain the present condition of these carvings, seven
years after the operations detailed had been completed Mr. Rogers
communicated with the Hon. Edward Cust, one of the trustees of the Earl
Brownlow who desired him to communicate with the clerk of the works at
Belton. Mr. G. A. Lowe. Mr. Lowe, in writing to Mr. Rogers, informed him
that “there is never any appearance of worm dust from the very beautiful
carving by Gibbons since you preserved it some years back.”
Mr. Rogers stated, at a meeting of the Royal Institute of British
Architects, a few years since, that similar carvings at Ditton Park,
Cashiobury, and Trinity College, Oxford, are in a state of decay, the
surface or skin, in some instances, being, covered with a deceptive white
vegetable bloom, which assists in completing the work of destruction.
Painting hastens the work of destruction. In the library of Trinity
College, Cambridge, some of the finest carved work at some former time
was thickly painted over, preventing the escape of the insects within,
which were compelled to feed on the last bit of woody fibre, leaving
nothing but the _skeleton_ of what it once was. At Cashiobury, where can
be seen room after room of the finest of Gibbons’ work, all this charming
carving (about thirty years ago) was covered over and loaded with a thick
brown paint and heavy varnish, destroying all the delicate feathering of
the birds and veining of the leafage, the repairs being done in plaster
or a composition. Flowers, each about the size of an orange, were thus
left with nothing but a skin of dust, with just enough fibre left to save
them from collapsing in the handling. All the glorious work of Gibbons in
the chapel of Trinity College, Oxford, was some years since covered with
a dirty, undrying oil.
We dislike painters who paint carvings as much as the servant who
applied to Mrs. H---- (wife of the celebrated landscape painter) for an
“appointment” as cook, and having ascertained that the master of the
house was a “painter,” remarked, “I cannot take the situation, ma’am, as
I have never lived in a _tradesman’s family_.”
It is a difficult process to remove paint from carvings, as it is not
possible to scour and wash it off in the ordinary way: it must be eaten
off by an alkaline solution.
With reference to the restoration of carvings which have not been
painted, but only blackened by time, they must be scoured by the careful
hand of an experienced man.
Mr. Penrose, the present architect to the Dean and Chapter of St. Paul’s,
a short time ago examined the beautiful carvings in St. Paul’s Cathedral,
and he was able to state that they have not hitherto been attacked by
worms. “Some portions had been broken by violence, but the state of
preservation was marvellous.” Mr. Rogers also observed that “he was
greatly and agreeably surprised--contrary to his expectations--to find
the carvings in St. Paul’s in so good a state of preservation, and so
free from the attacks of insects; but such was undoubtedly the fact. How
it was so he was not able to say.” Why was this? Well, Sir Christopher
Wren was a wise man, and when he erected St. Paul’s Cathedral, he engaged
an experienced mason to remain at the Portland stone quarries, whose
duty was to select every block of stone for the Cathedral, and when it
arrived in London it was placed _on its natural bed_. The good results
of this precaution can now be seen in the good preservation of the stone
at the present time. If he was so careful of the stone for the walls, no
doubt equal care was taken in the selection of the wood for carvings.
Besides, the _instructions_[36] to the commissioners for rebuilding St.
Paul’s were drawn up with a view of preventing decay. The following is an
extract from these instructions:
“And to call to your Aid and Assistance such skilful Artists, Officers,
and Workmen as ye shall think fit, and to appoint each of them his
several Charge and Employment; to minister to such Artists and Officers,
and to all and every other person and persons to be imployed in the said
service, to whom you shall think meet, such Oath or Oatlis for the due
performance of their several Duties, Employments, Offices, Charges and
Trusts to them or any of them to be committed as shall by you be thought
reasonable and convenient; and out of such Money as shall be received for
this Work, to allow to them, and every of them, such Salaries, Wages, and
Rewards respectively as to you shall seem fitting and proportionable to
their Employment and the Service they shall do.”[37]
Sir Christopher Wren was descended from Dutch ancestors: he was building
for a Dutch king, and we therefore perceive the reason why so much Dutch
wainscot was introduced by him into England.
It seems a great pity that the beautiful carvings of Grinling Gibbons and
others should be allowed to go to decay for want of proper attention.
Why should this be? We are acquainted with some of Gibbons’ carvings,
particularly those in St. James’s Church, Piccadilly, London; but whether
they are in a state of decay unknown to any one, whether any one looks
after them, or whether it is “nobody’s business” to do so, we cannot say.
Every now and then the owner of some beautiful wooden carvings suddenly
becomes acquainted with the fact that they are thoroughly riddled through
by worms, and instead of having them looked after, they are pointed at as
curiosities. Even the makers of “old furniture” take care that it shall
be bored all over, to imitate the borings of worms.
But what can be the cause of this decay? It must arise from one of two
causes; or, it may arise from both, viz. either the wood was not seasoned
when fixed; or else the quality and description of the wood for carving
purposes was not attended to. There cannot be smoke without cause, and
worms cannot exist unless a suitable habitation is first provided for
them. Hard white oak is close grained, and will scarcely admit moisture;
whilst on the other hand the soft foxy-coloured oak from some parts of
Lincolnshire, and other places, is so porous as to imbibe it easily and
retain it; and consequently is liable to early decay: in fine, the heart
of this is scarcely equal to the sap of hard white oak.
The English woods least liable to the worm for carvings are cedar,
walnut, plane, and cypress; those most liable are beech, pear, alder,
ash, birch, sycamore, and lime. All the fine carvings at Blenheim,
Kidlington, and Wimpole are in _yellow deal_, while in the age just
before nothing but lime-tree and soft wainscot were used. The beautiful
carvings of Gibbons, in the chapel of Trinity College, Oxford, are
wrought in costly scented cedar and rich dark oak; those in Trinity
College, Cambridge, in white lime-tree wood.
There is no doubt that wood to be used for carving should be hot,
pungent, and bitter: thoroughly obnoxious to wood-destroying insects. If
we cannot obtain this wood in England, we certainly can abroad, and one
shipload would last a long time for such purposes. Take, for instance,
the _Jarrah_ of Western Australia; the _Determa_, the _Cabacalli_, and
_Kakatilly_, of British Guiana; and the _Sepe_, of Trinidad: these woods
are much valued where they grow, and no insects ever attack them. We do
not say that they are suitable for wood carvings, but they might be
tried, and we certainly know they are not likely to be worm-eaten at
the end of a few years. They need not be discarded on account of their
hardness; boxwood is hard, but some good carvings have been executed with
boxwood. We can relate an anecdote about this wood. On 3rd June, 1867,
Mr. W. G. Rogers, the celebrated wood-carver (would that he were alive
now to read these words), was asked, at the Royal Institute of British
Architects, if boxwood is objectionable for wood carvings,[38] and he did
not reply to the question; if he had given his opinion it would have been
a valuable one, coming from such an authority. We must therefore get Mr.
Rogers’ opinion of this wood in another way. If the reader will refer to
the “Reports by the Juries,” English Exhibition, 1851, vol. ii., page
1555, he will find the following words:
“W. G. ROGERS, of London.--A cradle executed in boxwood for Her Majesty
Queen Victoria, and richly ornamented with carved reliefs; also, a group
of musical instruments, among which may be especially noticed a violin.
These works show an extraordinary dexterity in the treatment of the
material, and the ornaments of the cradle are in excellent taste. Prize
medal.”
We have already referred to the Report of the Commission on the Decay of
Wood Carvings, and as this report is now rather difficult to be obtained,
we propose condensing some extracts from it, which may prove of value to
the reader.
Of the three species of beetles injurious to furniture and carved work,
the first, _Ptilinus pectinicorius_ is about one-fourth of an inch
in length, and the male is distinguished by its beautiful branched
antennae; the second, _Anobium striatum_, which is by far the commonest
and most destructive, is about one-eighth of an inch long and of a brown
colour, with rows of small dots down the back; and the third, _Anobium
tessellatum_, is about one-third to one-fourth of an inch long, the back
varied with lighter and darker shades of brown scales.
These insects are produced from eggs deposited by the females in crevices
of the woodwork, from which are hatched small white fleshy grubs
resembling the grubs of the cockchafer in miniature, which generally
lie curled upon their sides,’ making very little use of their six small
feet fixed near the head; it is in this state that the insect is chiefly
injurious, although the perfect insect itself also feeds on the wood.
These grubs make their burrows generally in the direction of the fibre of
the wood; but when it becomes thoroughly dry and old, they burrow in all
directions.
When full grown they cease eating, cast off their larva skins, and appear
as inactive chrysalids with all the limbs lying upon the breast inclosed
in little sheaths: after a short time the perfect insect bursts forth.
The appearance of the insects in the perfect state takes place uniformly
during the first hot days at the beginning of summer. Where they take a
liking to a piece of woodwork, they seem to devour every particle of it,
and as the perfect insects possess large wings beneath their hard wing
sheaths, they are often seen flying in the hot sunshine out of doors,
evidently in search of suitable woodwork for themselves and their progeny.
Experiments were made by Mr. G. Wallis, Secretary to the Commission,
with a view of ascertaining the best means of stopping the decay when
commenced. The course pursued, as well as the results arrived at, will be
best illustrated by a summary of Mr. Wallis’s report on the subject.
The experiments may be placed under two heads, viz. Vaporization and
Saturation.
I. VAPORIZATION.
At the end of April, 1863, when, from the appearance of certain specimens
of carved work, the worm appeared to be developed and active, a large
glass case, made as air-tight as circumstances would permit, was filled
with examples of furniture, &c.
The bottom of this case was covered with white paper, and the specimens
of woodwork were raised above the surface by placing blocks of wood at
convenient points. This insured the free circulation of the vapour over
the whole surface of the objects. A dozen small saucers, with pieces of
sponge saturated with carbolic acid, were distributed about the bottom of
the case.
The raising of the objects on blocks of wood facilitated the placing of
these saucers at any desirable point.
The carbolic acid was, in this experiment, renewed every three or four
days for a month, and a strong vapour pervaded the case for that period,
daring which there was no appearance of worms, dead or alive. At the end
of May the saucers were removed, and the doors of the case thrown open,
so that it might be well ventilated and cleared of vapour, after which
it was closed again; but the saucers were not replaced. This closing
of the case without using the vapour was to prevent the escape of any
beetles which might make their appearance, in the event of the vapour of
the creosote not having destroyed the worms. About the middle of June,
a fortnight after the case was closed again, beetles were seen crawling
upon the white paper with which the bottom was covered. These beetles
would, no doubt, deposit their ova in the usual course, as they could not
escape, and a considerable number of them were found dead upon the white
paper with which the surface underneath the carved work was covered.
In order to test the efficacy of chloroform and benzine, two small glass
cases, as nearly air-tight as possible, were selected, in which were
arranged early in May specimens of ornamental woodwork, all more or less
in bad condition from the worm. The bottom of each, as in the previous
experiments, was covered with white paper; and the objects to be acted
upon raised upon small blocks of wood. In one case chloroform was used,
and in the other benzine in a similar manner to the carbolic acid, i. e.
by placing small pieces of sponge in saucers and saturating them with
the liquid, using five saucers in each case. Both the chloroform and the
benzine had to be renewed much oftener than the carbolic acid, as the
liquid evaporated much quicker.
Within a week after the experiment commenced it was evident that the
action of the chloroform had destroyed the worms as they came to
maturity, and in a fortnight all the specimens of carved work having been
taken from the case, and the dust produced by the action of the worms
shaken out, a number of dead ones were found, as also some dead beetles;
but these were evidently those of past seasons remaining in the crevices
of the woodwork.
On examining the specimens of carved work placed in the case treated with
benzine, there was no appearance of worms or beetles dead or alive.
The two cases, with their contents, were then kept open for a week, and
thoroughly ventilated to clear them as far as possible of all fumes of
either chloroform or benzine.
After this they were closed again, being then free from all traces of
vapour, and were not opened for some months. Throughout the summer, the
temperature being the same as that under which beetles appeared in the
case treated with carbolic acid, no traces of worms or insects were
visible, nor could the remains of any be discovered on the white paper,
with which the lower surface of each case was covered.
It would appear then, as far as vaporization is concerned, that the
action of the vapour of carbolic acid is not sufficient; in fact, it
is sluggish and heavy, whilst chloroform and benzine are volatile and
penetrating. The experiment with chloroform appears to prove that the
vapour kills the worm, and, as no beetles appeared in the case during
the summer, it may be inferred that it _killed all_ the worms within its
influence.
From the pungency and penetrative action of the benzine, as also its
volatile character and the fact that no life in the form of either worm
or beetle was manifested in the case in which it was used, it seems fair
to infer that it is more effective than even the chloroform.
Vaporization on a large scale might be adopted by having a room made
as air-tight as possible, stopping up the chimney, pasting the window
frames, &c., and placing infected furniture in the room, burning
brimstone, or filling the room with fumes of prussic acid, chloroform,
or benzine. It would have to be practised at the time when the perfect
beetles made their appearance; their destruction at that time involving,
of course, the prevention of further injury by their progeny.
II. SATURATION.
The experiments made with bi-chloride of mercury (corrosive sublimate)
and methylated spirits of wine were not so successful as by vaporization,
on account of the woodwork when dry (after having been saturated with the
solution) having a varnished appearance.
No experiment as to the effect of saturation in a solution of corrosive
sublimate in water was made: 1st, because of the great risk to delicate
carvings or pieces of furniture by their immersion in water, or the
bringing up of the grain of the wood by treatment with a brush; and 2nd,
because the vaporization by benzine appeared to be quite sufficient to
destroy the larvæ.
* * * * *
Before terminating this chapter, we trust a few words about carvers and
carvings will not be out of place.
There are two kinds of carvers, the _house carvers_ and the _ship
carvers_; the former are used to flat and square surfaces, the latter to
the rake or fay, as was the old term.
About the period of Louis XIV. Malines was remarkable for its wood
carvers, and the inhabitants might be seen sitting at their doors in the
streets, plying their art in the same manner as now in many of the German
and Swiss towns. Many works of art and decoration of Flemish origin are
still preserved in England;[39] the works of Flemish carvers in wood were
in great esteem, and there are numerous fine examples in the churches
of Norfolk, and other parts of England which may be regarded as their
productions. Evelyn remarked that Gibbons came from the Low Countries.
Grinling Gibbons created a school of carvers in England, and adopted
a style and manner in building up his fruit and flowers to produce a
grand effect. He chose but very few varieties of these out of his own
garden, and it is wonderful how he varied and played with those few. He
originated a peculiar description of light interlacing scroll-work,
which is to be met with in his best works; no one has successfully
attempted to carry it on since his time. There are several examples at
Belton, and in the chapel and state rooms at Chatsworth, in the fine
trophies at Kirthington Park; but the upper part of the reredos of St.
James’s, Piccadilly, is a marvellous specimen.[40] The horizontal bands
on the great organ in St. Paul’s Cathedral are the perfection of this
character of foliated scroll-work.[41]
Gibbons’ carvings have a loose freedom about them. At Chatsworth he
educated his workmen, who partook of his inspiration. There is a great
deal of his work scattered over the rooms, great hall, and staircase of
Lyme Hall, near Disley, which was erected under the direction of Sir C.
Wren. It was executed by the persons who were employed at Chatsworth, and
took nine years to complete.
At Blenheim there are some fine specimens of Chippendale’s work, but
what it all means is a mystery. Such a mixture of scraggy birds, and
flowers cut into shreds, pagodas, and rustic waterfalls--all this fine
workmanship employed to produce nothing but an incongruous whole of
absurd objects. There is a leading line in all these works, indicating
what the old carvers used to call the C and G style; because if you
attempt to draw it, it will resolve itself into these two letters. There
is also the S and G style.
Abolish painting and we shall again have some fine house carvers.
We have already given the conclusions at which the Commission appointed
by the Department of Science and Art arrived, as to the prevention of
decay or attack by these insects, and will now conclude this chapter
by quoting Dean Swift’s recipe for getting rid of the Anobium or Death
watch:--
“But a kettle of scalding hot water injected,
Infallibly cures the timber affected;
The omen is broken, the danger is over,
The maggot will die, the sick will recover.”
CHAPTER X.
SUMMARY OF CURATIVE PROCESSES.
The following summary of the most approved formula for preventing and
curing the evils of rot is prepared from the works of Tredgold and
Wylson; some other more modern receipts have been added from ‘The
Builder,’ ‘Architect,’ ‘Building News,’ and other professional periodical
publications. Discretion in their use is recommended, and in serious
cases we decidedly recommend consulting a professional man who is well
acquainted with the subject.
TO PRESERVE WOODWORKS THAT ARE EXPOSED TO WET OR DAMP.
1. For those of an extensive nature, such as bridges, &c. The Hollanders
use for the preservation of their sluices and floodgates, drawbridges,
and other huge beams of timber exposed to the sun and constant changes of
the atmosphere, a certain mixture of pitch and tar, upon which they strew
small pieces of shell broken finely--almost to a powder--and mixed with
sea-sand, and the scales of iron, small and sifted, which incrusts and
preserves it effectually.
2. A paint composed of sub-sulphate of iron (the refuse of the copperas
pans), ground up with any common oil, and thinned with coal-tar oil,
having a little pitch dissolved in it, is flexible, and impervious to
moisture.
3. Linseed oil and tar, in equal parts, well boiled together, and used
while boiling, rubbed plentifully over the work while hot, after being
scorched all over by wood burnt under it, strikes half an inch or more
into the wood, closes the pores, and makes it hard and durable either
under or out of water.
4. For fences, and similar works, a coating of coal-tar, sanded over; or,
boil together one gallon of coal-tar and 2½ lb. of white copperas, and
lay it on hot.
TO PREVENT ROT.
1. Thoroughly season the wood before fixing, and when fixed, have a
proper ventilation all round it.
2. Charring, after seasoning, will fortify timber against infection, so
will a coating of coal-tar.
TO CURE INCIPIENT DRY ROT.
1. If very much infected, remove the timber, and replace with new.
2. A pure solution of corrosive sublimate in water, in the proportion of
an ounce to a gallon, used hot, is considered a very effectual wash.
3. A solution of sulphate of copper, half a pound to the gallon of water,
laid on hot.
4. A strong solution of sulphate of iron; this is not so good as sulphate
of copper.
5. A strong solution of sulphates of iron and copper in equal parts,
half a pound of the sulphates to one and a half gallon of water.
6. Paraffin oil, the commonest and cheapest naphtha and oil, or a little
resinous matter dissolved and mixed with oil, will stay the wet rot.
7. Remove the parts affected, and wash with dilute sulphuric acid the
remaining woodwork.
8. Dissolve one pound of sulphate of copper in one gallon of boiling
water, then add 1¼ lb. of sulphuric acid in six gallons of water, and
apply hot.
TO PREVENT WORMS IN TIMBER.
1. Anointing with an oil produced by the immersion of sulphur in
aquafortis (nitric acid) distilled to dryness, and exposed to dissolve in
the air.
2. Soaking in an infusion of quassia renders the wood bitter.
3. Creosoting timber, if the smell is not objectionable.
4. Anointing the timber with oil of spike, juniper, or turpentine, is
efficacious in some degree.
5. For small articles, cover freely with copal varnish in linseed oil.
TO PREVENT WORMS IN MARINE BUILDING.
1. A mixture of lime, sulphur, and colocynth with pitch.
2. Saturating the pores with coal-tar, either alone or after a solution
of corrosive sublimate has been soaked and dried into the wood.
3. Sheathing with thin copper over tarred felt is esteemed the best
protection for the bottoms of ships for all marine animals; the joints
should be stopped with tarred oakum.
4. Studding the parts under water with short broad-headed nails.
TO DESTROY WORMS IN CARVINGS.
1. Fumigate the wood with benzine.
2. Saturate the wood with a strong solution of corrosive sublimate: if
used for carvings, the colour should be restored by ammonia, and then by
a weak solution of hydrochloric acid; the holes may be stopped up with
gum and gelatine, and a varnish of resin dissolved in spirits of wine
should afterwards be applied to the surface.
3. Whale-oil and poisonous ointments have been found of service.
The wood should be carefully brushed before being operated upon.
TO DESTROY ANTS AND INSECTS IN WOOD.
1. Corrosive sublimate is an effectual poison to them.
2. Oils, especially essential oils, are good preventives.
3. Cajeput-oil has been proved effectual for destroying the red ant.
4. Payne’s, Bethell’s, and Burnett’s processes are said to be proof
against the white ant of India.
5. Dust the parts with pounded quicklime, and then water them with the
ammoniacal liquor of gas-works, when the ammonia will be instantly
disengaged by the quicklime, and this is destructive to insect life.
6. For the black ant, use powdered borax; or smear the parts frequented
by them with petroleum oil; or syringe their nests with fluoric acid or
spirits of tar, to be done with a leaden syringe; or pour down the holes
boiling water to destroy their nests, and then stop up the holes with
cement. Ants dislike arsenic, camphor, and creosote.
The preceding remedies are not by any means given with the intention of
superseding the previous chapters, which should be carefully studied by
those who wish to acquire a moderate knowledge of the subjects.
CHAPTER XI.
GENERAL REMARKS AND CONCLUSION.
Our task is nearly completed: we have but few general remarks to make.
The decay of wooden sleepers, posts, &c., on our railways and the
destruction of timber piles by worms have been the causes of directing
the attention of engineers to the preservation of timber. Most of our
leading engineers now have the greater portion of the timber used
in their works either creosoted or injected with chloride of zinc.
Architects, as a rule, do not, unfortunately, adopt any process for
preserving timber from rot and decay; and have practically no guarantee
that timber used in their works has been thoroughly seasoned: posterity
will not thank them for this, and yet they are not solely to blame. The
fault in a great measure rests with the public, who require buildings to
be erected at the least cost and in the shortest possible time. Moreover,
the works executed by our leading builders are so extensive, that they
have no room in their yards for large piles of timber to lie and season;
and even if they had room it is doubtful if they would allow so much
material, representing money, to remain idle. We are acquainted with one
instance where a London architect, about a dozen years ago, erected a
public building. The front of the reporters’ gallery was formed of oak
panelling; and within a year after the completion of the building narrow
slips or tongues of wood had to be let in in several places to fill up
the holes formed by the shrinkage of the panels. Similar cases to this
are by no means rare. We can quote another instance of unseasoned wood.
A range of workshops was erected a few years since in South London; the
principals of the roof were not ceiled; almost before the building was
finished the upper floor was occupied by a battalion of workwomen. The
heat of the room (the ventilation being defective) soon had an effect
upon the tie-beams, but one beam, which we imagine was unseasoned, in
consequence of large shakes and splits, had to be taken out and replaced
with new. We will (as a lawyer would say), cite one more case. A church
in Surrey required some extensive repairs to the roof: an architect and
a builder were employed, and the necessary works were done. Within four
years dry rot has made its appearance on the new timbers of the roof (not
an air-tight one). One of the churchwardens, on consulting us last year
(1874) as to the best means of stopping the rot, energetically remarked,
“Who is responsible to us for this, the architect or the builder?”
Charles Dickens, in his edition of ‘Bleak House’ in 1868, wrote, with
reference to long Chancery suits, “If I wanted other authorities for
Jarndyce and Jarndyce, I could rain them on these pages.” We are able to
make a similar remark with reference to any more instances of dry rot.
According to the 7th chapter of the First Book of Kings, “Solomon was
building his own house thirteen years:” we cannot spare so much time
now-a-days over the erection of a house, but that is no reason why our
timber should not be naturally or artificially seasoned.
If we cannot obtain naturally seasoned timber, by all means let us
have artificially seasoned wood. Tredgold, in his Report on Langton’s
system,[42] nearly arrived at the secret. We will quote a few words from
his Report:
“Mr. Langton having discovered a new method of seasoning timber … by
which the time necessary to season green timber, and render it fit for
use, is only about twice as many weeks as the ordinary process requires
years; … it is more economical, and locks up less capital than the common
method.”
We believe we may say that the number of our public buildings which
have been erected during the present century with artificially prepared
timber can be counted on our eight fingers (without troubling our thumbs)
and not exceed that number;[43] and yet we hear of dry rot in the great
dome of the Bank of England and other buildings without profiting by the
events. We should like to know if the wooden dome of St. Paul’s Cathedral
is safe from dry rot, (the domes at the Panthéon and the Halle-au-Blé at
Paris were affected,) _and plumbers fires_.
It is evident that a preservative process, thoroughly suitable for
everyday use and applicable to buildings, has yet to be invented: it
should be cheap, should render wood uninflammable, should preserve the
wood from decay and dry rot, _should not harden the wood until some time
after its application_, and should be colourless and invisible. The
invention of such a process will require careful thought and experiments,
for it appears to us that the whole theory of any successful plan for the
prevention of the dry rot must resolve itself into the _solidifying or
coagulation of albumen_: this means hardening the sap-wood, and causing
increased difficulty in working the wood. We can easily illustrate
our remarks, by quoting one of the latest patents for preserving
timber, which has recently been made public. It is the invention of a
gentleman living in England, who has discovered a means of making wood
uninflammable, preventing dry rot and decay, and rendering white and
yellow pine, both in hardness and appearance, like teak and oak. We have
no objection to its rendering wood uninflammable, providing it does
not “hurt” the wood; but can the reader believe that any architect, in
erecting a moderate-sized villa, would specify that all the joiners’
work, staircases, window-frames and sashes, architraves, skirtings,
doors, &c., must be formed of wood _as hard as teak_; or rather, can
the reader imagine the architect’s client would be agreeable to pay the
greatly increased cost for the extra labour involved. We do not think
this invention will ever be used, at least to any extent, in buildings.
Much yet remains to be done with regard to uninflammable wood for
buildings: we think the matter should be dealt with (with reference to
joists, floor boards, partitions, doors, staircases, roof timbers, &c.)
by a new Buildings Act of Parliament. Stone and iron will not burn, but
they are not fire-resisting: brick, artificial stone, and incombustible
wood will give us all we desire; the details may be difficult of
arrangement, but builders would comply with them if they were
imperatively required. At present our houses are formed of brick walls,
every room being separated vertically and horizontally from the adjoining
rooms by combustible wooden walls. A street built up of fire-proof
buildings would be a novelty. The whole subject requires to be dealt with
thoroughly, for while we have combustible wooden floors, partitions, &c.,
we cannot at the same time have a fire-proof building. We have not been
able to spare the space, or else we should have devoted a long chapter to
this subject; a superficial consideration (such as alum and water) would
have been practically useless.
In conclusion, we can only summarize our remarks on the cause of dry rot,
by saying, “Season and ventilate,” in every case: as to the cure, that
is not so easy to deal with. If the reader has ever had a decayed tooth
aching, a friend has probably said, “Have it out;” and we say, wherever
there is a piece of timber decayed in a building which can be removed,
“Have it out, and stop up with new;” and in so advising we are merely
following the advice to be found in a good old volume, which has never
yet been equalled, and which says:
“And, behold, if the plague be in the walls of the house with
hollow strakes, greenish or reddish, which in sight are lower
than the wall; … Then the priest shall command that they take
away the stones in which the plague is, and they shall cast them
into an unclean place without the city: And he shall cause the
house to be scraped within round about, and they shall pour out
the dust that they scrape off without the city into an unclean
place: And they shall take other stones, and put them in the
place of those stones; and he shall take other mortar, and shall
plaister the house.”--_Leviticus_ xiv. 37, 40, 41, and 42.
This course will not, however, suit every case, for when the rot has
spread in many directions, the best and cheapest course is to consult
some professional man, well versed in the peculiarities of dry rot,
before determining upon any remedy, for we have shown in the course of
this work that the disease may arise from various causes; and it is not
a difficult matter to select the wrong remedy, and thus increase the
disease.
We trust the reader has found in this volume at least some hints which
may be of service to him. A _new_ house affected with dry rot is an
unhealthy one to live in, and an _old_ one is worse than the new; we mean
the kind of house referred to in one line by an American poet, as follows:
“O’er whose unsteady floor, that sways and bends.”
LONGFELLOW.
FOOTNOTES
[1] See white faces of workmen.
[2] See London newspapers, July, 1812.
[3] ‘Fire Surveys,’ p. 58.
[4] ‘Directions to Cure the Dry Rot.’ 1807.
[5] See Report of the Officers of Portsmouth Yard, 1792.
[6] See Tredgold’s Report on this process, May 2, 1828.
[7] See No. 1, p. 3, Appendix to first volume of ‘Naval Architecture.’
[8] See paper on “Kyan’s Process” by Captain R. C. Alderson, C.E., in
vol. i. ‘Papers of Royal Engineers.’
[9] See Chapman, Boydon, Jackson, and Kyan’s methods.
[10] See ‘London Journal of Arts,’ March, 1842; ‘Bull. de
l’Encouragement,’ June, 1842.
[11] See ‘Repertory of Patent Inventions,’ December, 1836.
[12] See ‘Étuves de Désiccation et Appareil pour l’lnjection des Bois.’
Par MM. Dorsett et Blythé, manufacturiers, à Bordeaux. 1859.
[13] See ‘Repertory of Patent Inventions’ April, 1847.
[14] See Chap. IV., p. 97.
[15] See coating for piles, p. 161.
[16] See ‘Proceedings of the Royal Society of Edinburgh,’ v. 7, page 433;
‘Tredgold’s Carpentry’ by J. T. Hurst, 1871; ‘Histoire de l’Acad.,’ 1765,
page 15; ‘Ann. des Ponts et Chaussées,’ v. 15, page 307; ‘Mem. sur la
Conservation des Bois à la Mer,’ 1868, by Forestier; ‘Bois de Marine,’ by
Quatrefages, 1848.
[17] There are eight kinds of _teredines_, of which three are to be found
in European waters, viz. the _Teredo fatalis_, _Teredo navalis_, _Teredo
bipennata_.
[18] See ‘Memoirs of Sir M. I. Brunel;’ also, for particulars of the
construction of the shield designed by him for forming the Tunnel,
Weale’s ‘London Exhibited,’ and ‘A Memoir of the Thames Tunnel,’ in
Weale’s Quarterly Papers on Engineering.
[19] Note geometrical framing in spider’s web.
[20] ‘Reports of the Juries,’ Exhibition, 1851. ‘Reports’ by Dr. Gibson,
Conservator of Forests, Bombay Presidency. ‘Reports’ by Dr. Cleghorn,
Conservator of Forests, Madras Presidency. ‘Reports’ by Mr. H. B.
Baden Powell, Inspector-General of the Forest Department, India, 1875.
‘Reports’ on the Teak Forests of Tenasserim, Calcutta, 1852. Papers by
Mr. Mann and Mr. Heath on ‘Decay of Woods in Tropical Climates,’ Inst.
C.E., 1866. Paper on ’ The Ravages of the Limnoria Terebrans,’ by Mr. R.
Stevenson, Royal Society, 1862. ‘Account of the Bell Rock Lighthouse,’
by Robert Stevenson, 1824. Stevenson’s ‘Design and Construction of
Harbours.’ Smeaton’s ‘Reports.’
[21] See ‘Sur un Moyen de Mettre tous les Approvisionnements de Bois de
la Marine de la Piqûre des Tarets’ (Compte. rend., Janv. 1848).
[22] ‘Report of German Commission relative to rendering Woodwork and
Stage Materials Incombustible.’ Professor Fuchs and Dr. Pettenkofer’s
Reports. Dr. Feuchtwanger’s works. M. Kuhlman’s pamphlet. ‘Reports
relative to Ransome’s Process.’ Note M. Szerelmey’s patent, 21 July, 1868.
[23] See ‘Memoirs on the Use of Cast Iron in Piling,’ by Mr. M. A.
Borthwick, ‘Trans. Inst. Civ. Eng.’ vol. i. No. 22.
[24] See Hurst’s ‘Tredgold’s Carpentry,’ p. 380, 1871. London.
[25] See Charlesworth’s ‘Magazine of Natural History,’ 1838, Art.
_Myrmica domestica_. Also, ‘Boston Journal of Natural History,’ 1834, p.
993, Art. _Myrmica molesta_.
[26] Thunberg’s ‘Travels,’ vol. ii. p. 300.
[27] ‘Expedition to Surinam.’ By Captain Stedman. 1813. London.
[28] Kœmpfer’s ‘Japan,’ vol. ii.
[29] ‘Voyage de Spartmann au cap de Bonne-Espérance: voy. _Dict. d’Hist.
Nat._ de Guérin.’ 1839.
[30] See Paper by Mr. J. B. Hartley, read before the Institution of
Civil Engineers, London, 23rd June, 1840, “On the Effects of the Worm on
Kyanized Timber exposed to the Action of Sea Water; and on the Use of
Greenheart Timber from Demerara.”
[31] Margary’s process failed to preserve wood from rot on the Bristol
and Exeter Railway, England.
[32] See Paper by Mr. Thomas Hounslow, of the Royal Engineers’
Department, published in ‘Engineering,’ p. 198, 21st September, 1866.
Also, Hurst’s edition of ‘Tredgold’s Carpentry,’ page 380. 1871. London.
[33] See Maconochie’s suggestion, p. 163.
[34] ‘Insects Abroad.’ By the Rev. J. Wood. 1874. London.
[35] ‘Histoire de l’Académie,’ p. 38. 1705. See also M. Maxime Paulet’s
communication to the Academy, 27th April, 1874.
[36] Their Majesties’ Commission for the Rebuilding of the Cathedral
Church of St. Paul, in London. London: Printed by Benjamin Motte. 1692.
[37] Workmen would now think this clause a striking one.
[38] See lecture by Mr. W. G. Rogers, “On the Carvings of Grinling
Gibbons,” delivered at the Royal Institute of British Architects, 3rd
June, 1867.
[39] Paper by M. de Laperier, of the Belgian Legation, read at a meeting
of the Society of Antiquaries, relative to Flemish origin of English
carving.
[40] The large pulpit is not from the design of Sir Christopher Wren, nor
is the carving by Grinling Gibbons.
[41] See engraving in the ‘Art Journal,’ 1866.
[42] See Tredgold’s Report on this process, May 2, 1828.
[43] See Bartholomew’s’ Specifications,’ and Professor Donaldson’s
valuable work on ‘Specifications,’ which comprises many examples by
modern architects. The usual clause is: “The timber to be well seasoned
(is it?), free from large knots, shakes, and other defects.”
INDEX.
Abel’s silicate of soda process, 160
Academy of Sciences, Holland, report on sea-worms, 235
Acetate of lead, 226
” iron and wood tar, 130
Acid, carbolic, 257, 276
” fluoric, 287
” hydrochloric, 286
” hydro-fluo-silicic, and other substances, 166
” nitric, 98, 285
” pyroligneous, 111, 144, 263
” sulphuric, 161, 285
” vegetable, 111
Age of trees, how to ascertain, 9
Air, admission of, to prevent or cure rot, 27, 171, 187, 284, 292
Alberti (L. B.), on seasoning wood, 66, 75
Alcohol, in corrosive sublimate, 263, 265, 266, 279
Alderson’s (Captain), experiments with woods, 127
Alkali, caustic, 122
Alum, to prevent combustion, 118
” experiments with, 119
” and other substances, 156, 166, 167
American method of preserving ships’ masts, 111
” oak, inferior to English, 40
Ammonia, to cure rot, 118, 137
” and other substances, 131, 286
Amsterdam, built on piles, 23
Annual rings in wood, 8
Ants, black, how to destroy, 287
” white, description of, 240
” ” how to destroy, 251, 286
” ” in Australia, Bahia, and Pernambuco, 245
” ” in Batavia, 247
” ” in Brazil, 244
” ” in Ceylon and the Philippine Islands, 246
” ” in France and Japan, 248
” ” in India, 251
” ” in Jamaica, 241
” ” in Spain, Senegal, and Surinam, 248
” ” woods which resist, 249
Armstrong’s (J.), account of rotten floor, 43
Arsenic, 224, 252, 287
” experiments with, 167
” and other substances, 253
Asphalte, to keep out damp, 179
Australian method of seasoning Jarrah wood, 115
Baker’s (J.), case of dry rot in Baltic wood, 177
Ballast for railway sleepers, 48, 138
Bank of England, dry rot in dome, 42
Banks (Sir J.), on growth of fungi, 44
Barium sulphide, to preserve wood, 156
Barlow’s patent process, 102
” on seasoning wood, 78
Barnacles on timber piles, 223, 226
Barry (Sir C.), on steaming wood, 90
Baryta, and other substances, 166
Basement stories with damp, 23, 181, 182, 187
Bayonne, girder in church at, 174
Beams, advantage of sawing, 32
Bees, carpenter, destroy wood, 240, 259
” wax, and other substances, 156
Beetles, in wood, 262, 275
” how to destroy, 286
Belgian engineers prefer charred sleepers, 96
Belidor, on felling trees, 54
Belton House (Earl Brownlow’s), beetles in carvings at, 268, 281
Bentham (Sir S.), on drying oak, 91
Benzine, to destroy wood beetles, 266, 277, 286
Berkeley, on fungi, 21
Bethell’s (J.), patent creosoting process, 130, 155, 224, 234, 286
” ” drying stoves, 86
Binmer, on steaming and charring, 99
Biot, on pressure process, 144
Blenheim, state of carvings at, 281
” carvings in yellow deal at, 273
Blood, and other substances, 167
Bond timber, decay of in walls, 45, 174
Borax, a receipt for black ants, 287
” and other substances, 156
Boucherie’s (Dr.), sulphate of copper process, 146
Bourne’s (J.), experiments with wood, 254
Bowring’s (Sir J.), account of ants in Obando, 247
Boyden’s (A.), remedies for dry rot, 95, 112, 122
Brande (Dr.), on preserving woods, 139, 142, 155
Bréant’s patents, 145
Brick dust, tar, &c., to preserve piles, 228
Brimstone, bees-wax, &c., to preserve wood, 156
Brochard and Watteau’s process, 80
Browne’s (Sir S.), experiments with piles, 229
Brunei (Sir M. I.), 138, 139, 215, 228
Buffon, 144, 198
Builders, bad, 182, 202
Building, hints on, 180
Burnett’s (Sir F.), patent zinc process, 140, 224, 254, 255, 286
Burt’s experience of creosoted sleepers, 137
Cadet de Gassicourt’s process for dry rot, 144
Calomel, composition of, 264
Calvert’s caoutchouc process, 162
Camphor disliked by ants, 287
Canadian white spruce deals liable to warp, 65
” yellow wood liable to rot in damp situations, 36, 43
Caoutchouc, solution of, 162
” and other substances, 163
Carbolic acid, for wood beetles, 257, 276
Carbonate of soda (Payne’s process), 154
Carbonization by gas, 97, 164
Carpenter bees destroy wood, 240, 259
Carpenter (Dr.), on growth of fungi, 43
Carvers, wood, 280
Carvings destroyed by worms, 266
” how to clean, 270
” to destroy worms in, 286
Cashiobury, carvings at, destroyed by beetle, 269
Cement, to protect piles, 227, 228
Ceylon, ants in, 246
Chalk, and other substances, 161
Champy’s tallow process, 144
Chapman (W.), on dry rot, 25, 73, 112, 119, 122, 165, 167
Charcoal--_see_ Oils, Whale, and Fish--to preserve wood, 121
” and other substances, 157
Charpentier’s hot air patent, 80
Charring wood, 95
” when useful, 100
” and pitching, 96
Chassloup Lambat’s suggestion to prevent rot, 163
Château of the Roques d’Oudres, girders at, 174
Chatsworth, Gibbons’ carvings at, 281
Chelura terebrans destroy piles, 219
Chemists prefer thin creosote, 131
Chinese method of preserving wood, 167
Chippendale’s carvings, 281
Chloride of calcium, 146
” of manganese, 154
” of sodium, 164
” of zinc--_see_ Burnett’s Process
Chlorine gas, and other substances, 123
Chloroform, for wood beetles, 277
Chunam, and cocoa-nut oil, 107
Church at Bayonne, fir girders in, 174
” of Holy Trinity, Cork, rot in vaults, 39
” in London, rot in roof, 184
” in Surrey, 289
” of St. Mark, Venice, rot in curb, 176
” of Old St. Pancras, London, rot in vaults, 40
Cleghorn (Dr.), on creosoted sleepers, 47, 136, 142
Coal Exchange, flooring of, 81
” tar, 170, 233, 246, 256, 262
” ” and other substances 123, 284, 285
” vessels last long, 117
Cobley’s patent lime process, 166
Colocynth and quassia, 263
” and other substances, 285
Colouring woods, 108
Commission, report of, on carvings, 266, 274
Cooke’s (M. C.) instance of fungi, 43
Copal varnish, 191, 197
” in linseed oil, 285
Copper, red oxide of, 161
” prussiate of, 146
” sulphate of--_see_ Sulphate of Copper
” nitrate of, 226
” sheathing against sea-worms, 228
” ” and tarred felt, 285
Copperas, and coal tar, 284
” to preserve ships, 112, 226
Cork, for ends of brestsummers, 174
Corrosive sublimate, 123, 226, 264, 265, 285, 286
” and other substances, 130, 155, 263, 265, 266,
279, 285
Covent Garden Theatre, dry rot in bond, 175
Cow-dung mortar, and oils, 251
Creosote (Bethell’s patent), 118, 130, 133, 142, 165, 230, 236, 255,
257, 285, 287
” vapour, 145
” and chloride of zinc, 133
Crepin (M.), on creosoted wood, 139, 236
Cryptogamia, or fungi, 15
Cullen’s process for dry rot, 157
Dammer oil, and other substances, 255
Damp, 176, 177, 178, 181
” a cause of decay in wood, 22
” rooms, how to ascertain, 24
Darwin’s process for dry rot, 156
Daviller (A. C.), on felling trees, 54
Davison and Symington’s process, 81
Davy (Sir H.), on corrosive sublimate, 127, 263
Deals require long seasoning, 64
” how sometimes imported, 35
Deane’s (Sir T.), account of dry rot case, 39
Decay of trees, symptoms of, 33
De Lapparent’s processes, 73, 97, 163
Desiccating processes, 81
Dickson (Dr.), on Kyan’s process, 130
” (J.), on seasoning wood, 75
Ditton Park, carvings destroyed at, 269
Donaldson’s (Prof. T. L.) account of dry rot case, 42
Dondeine’s paint, 165
Dorsett and Blythé’s copper process, 151
Doswell’s report on timber piles, 232
Dram battens liable to rot, 8
Dry rot, wet rot, and rot.
” appearances of, 31, 35
” causes of, 24
” danger of, 34
” how different from wet rot, 14
” proceeds according to temperature 29, 187
” caused by bad building, 182
” ” mortar, 44, 173, 177
” ” damp brickwork, 44, 182
” ” ” ground, 20, 21
” ” ” stone, 44
” ” heat and moisture, 23
” ” insufficient areas, 178
” ” ” tarpaulings, 184
” ” joining different woods, 176
” ” kamptulicon, 187
” ” Keene’s cement, 188
” ” oiled cloth, 185
” ” old trees, 183
” ” partial leaks, 23
” ” want of air, 171, 172, 186, 187, 188
” ” ” proper drains and spouts, 41
” increased by stoves, 172
” _in ground_, under house at Hampstead, 20
” _under foundations_, Norfolk House, 176
” ” ” Grosvenor Place, 176
” ” _floor_, Stanmore Cottage, 183
” ” _hearthstone_, 43
” ” _pavement_ at Basingstoke, 43
” _on paved floor_, Westminster Hall, 44
” _in vaults_, Old St. Pancras Church, 40
” _on vaults_, Holy Trinity Church, Cork, 39
” in cask in cellar, 43
” ” _basement floor_ of house, Greenwich, Frontispiece
” ” _ground floor_ of houses, 43, 177, 185, 186, 187
” ” _first floor_ of house, No. 29, Mincing Lane, 187
” ” _second floor_ of house, No. 79, Gracechurch Street, 187
” ” _barn floor_, 42
” _on floor_ of house, No. 106, Fenchurch Street, London, 186
” _in wood bond_, Covent Garden theatre, 175
” ” _damp closet_, or pantry, 16
” ” _wood lining_ to walls--basement, 125
” ” floor of house in the Temple, London, 124
” ” _brestsummer_ of shop, 42
” ” _girder_ of house (Earl of Mansfield’s), 32
” ” ” building at Malta, 32
” ” _partition_, No. 16, Mark Lane, London, 188
” ” _roof_, church in London, 184
” ” ” ” Surrey, 289
” ” _curb of dome_, St. Mark’s, Venice, 176
” ” _dome_, Bank of England, 42
” ” ” Halle-au-Blé, Paris, 42
” ” ” Panthéon, Paris, 42
” ” Society of Arts building, Adelphi, 42
” ” _field gates_, 183
” ” _foreign timber_, 35
” ” _paling_ 125
” _in ships_, 23, 26, 73, 93, 112, 114, 172
” prevented by seasoning, 63
” good, cheap, and easy remedy required, 291
Du Hamel, 66, 72, 144
Duke of Devonshire’s house, dry rot at, 40
D’Uslaw’s, Meyer, steam process, 102
Dutch method of coating piles, 221
Earl Brownlow’s house, beetles in carvings at, 268
” of Mansfield’s house, rotten yellow fir girder at, 32
Emerson’s boiled oil process for rot, 110
Endogenous stems, grow from within, 4
Engineers, English, 139, 288
” foreign, rules for sulphate of copper, 151
” ” ” creosote, 131, 133
Evelyn (Sir J.), on seasoning wood, 53, 73, 75
Exogenous stems, grow from without, 4
Faraday (Prof.), on corrosive sublimate, 129, 263
Felt, tarred, and copper sheathing, 285
Fences, how to prevent them rotting, 46, 161
Fenchurch Street, No. 106, dry rot on floor, 186
Feuchtwanger’s (Dr.), water-glass for piles, 226
Field gates, dry rot in, 183
Fire-proof houses, cost of, 143
” ” necessity of, 291
Flemish carvings in England, 280
Flockton’s wood tar process to preserve wood, 130
Floor-cloths, injurious effects of, 185
Floors, how to protect from worms, 266
” dry rot in, 20, 39, 40, 42, 43, 44, 125, 176, 182, 183,
186, 187
” ” Frontispiece
Fluoric acid, for the black ant, 287
Fontenay’s metallic soap, to preserve wood, 165
Forestier’s experiments with creosoted piles, 139, 236
Foundations, how to build, 179
Fraser’s (Capt. A.) paint for white ants, 253
Fungi differ according to situation, 22
” explanation of the term, 15
” forms and strength of, 31, 43
” production of, 15, 18, 19, 20
” rapid growth of, 44
Gambir composition for white ants, 255
Garlic and vinegar for worms, 106
Gas, carbonization of wood by, 97, 164
” chlorine, and other substances, 123
Gibbons’ (Grinling), carvings, 260, 280
Glue, solution of, to preserve ships, 112
” and other substances, 112, 122, 130
Gracechurch Street, No. 79, dry rot in second floor, 187
Graham (Prof.), on Burnett’s process, 140
Grease, how to take it out of floor, 191
Greenwich, rot in floor of house at, Frontispiece
Greville’s (Dr.) description of fungi, 21
Groo-groo worms in Surinam, 247
Grosvenor Place, rotten planking in houses, 176
Guibert’s smoke process, 93
Hales’ (Dr.) oil and creosoting processes, 111, 118
Halle-au-Blé, Paris, dry rot in dome of, 42
Haller’s (Dr.) analysis of a fungus, 31
Hampstead, dry rot in ground of house at, 20
Hancock’s caoutchouc and oil process, 162
Hartley’s experiments with fire-proof house, 120
Hawkshaw’s opinion of Payne’s process, 155
Higgins’ (Dr.) ammonia remedy for rot, 118
House, fire-proof, 120
” ” cost of, 143
” badly erected, 182, 202
Howe’s experiments with posts, 45
Humboldt, Baron, on damp rooms, 24
Indestructible Paint Company, 195
Indian Woods, 47, 134, 223, 250
Ingredients for preserving wood, 168
Iron, cast, effect of sea-water on, 230
” muriate of, 157
” prussiate of, 146
” pyrolignite of, 130, 146, 151, 156, 234
” sulphate of, 154, 157, 284
Jackson’s preserving processes, 111
” (G.) experiments with white ants, 254
Jagherry, or coarse Indian sugar, for mortar, 253
Japanese method of treating graining, 194
Jarrah wood, how seasoned, 115
Johnson’s (B.) account of rot in floor, 42
Jones’ (Major, R. E.) report on rotten beams, 32
Kamptulicon causes dry rot in floors, 187
Kenwood, rotten fir girder at, 32
Kidlington, carvings in yellow deal at, 273
Kirthington Park, Gibbons’ carvings at, 281
Knabb’s sulphate of copper process, 152
Kœnig’s opinion of sulphate of copper, 152
Kyan’s corrosive sublimate patent, 123, 205, 223, 233
Lampblack, and fish oil, 108
Langton’s extraction of sap process, 101
Lead, 173, 179, 200
” and tarred rope for piles, 228
” oxide of, and other substances, 123
Légé and Fleury-Pironnet’s copper patent, 149
Le Gras’ manganese, zinc, and creosote patent, 164
Lepisma worm destroys boats, 221
Letellier’s preserving processes, 130, 165
Lewis’ lime process, 112, 116
Liebig (Baron) on decay of wood, 19
Lime, to preserve wood, 112, 116, 253, 286
” and other substances, 107, 117, 156, 157, 166, 255, 285
” re-carbonated, injurious to wood, 116
” water, to preserve ships, 116, 122
” ” ” basement joists, 116
” ” and sulphuric acid, 156
” vessels last long, 116
Limnoria terebrans, description of, 217
” ” how it destroys piles, 218
Linseed oil--_see_ Oils
Litharge ” ”
Logs, state of, on arrival in England, 37
Lowestoft Harbour, creosoted piles in, 230
Lukins’ stove process, 121
Lycoris fucata, destroys the Teredo navalis, 237
Lyme Hall, carvings at, 281
Maconochie’s suggestions for preserving wood, 121, 145, 163
McMaster (B.), on decay of railway sleepers, 47
McWilliam, on fungi, 20, 22, 29
Makinson, on creosoted piles, 231
Malta, rotten girders in building at, 32
Manganese, and other substances, 163, 165
Mann’s (Capt.) and McPherson’s (Capt.) experiments, 255
Margary’s patent sulphate of copper process, 130, 150, 254
Mark Lane, No. 16, dry rot in partition at, 188
Marshall (G.), on seasoning oak, 69
Maun (G. O.), on sleepers, Pernambuco railway, 138
Mecquenem’s desiccating process, 80
Mellis (J. C.), on creosoted wood, 256
Melseun’s experiments with ammonia, 137
Mercer’s Hall, decay of carvings at, 267
Mercury, deuto-chloride of, 165
” bi-chloride--_see_ Corrosive Sublimate
Merulius lachrymans, dry rot fungus, 21
Methods for seasoning wood, 168
Methylated spirits of wine for carvings, 279
Michigan Central Railroad bridge, dry rotten, 185
Migneron’s process, 144
Miller’s hot air process, 102
Mincing Lane, No. 29, dry rot in first floor at, 187
Moll’s vapour of creosote process, 145
Moon, age of, a guide for cutting trees, 56
Mortar made with sea sand objectionable, 113, 181
” cow-dung and castor oil, 251
Mud and other substances to preserve wood, 253
Müenzing’s manganese process, 154
Mundic, to preserve wood, 118
Muriate of iron (Toplis’ process), 157
Nails, scupper, for piles, 228, 286
Neamann, on seasoning wood, 79, 117
Nichols (T.), on sand bath, 116
Nitrate of copper for piles, 226
Nitric acid, for worms, 285
Norfolk House, rotten planking at, 176
Norway white lowland deals warp, 65
Nystrom’s process, to prevent combustion, 166
Oak, American, liable to rot, 40
” different qualities of, 71
” good and bad, 25
” seasoning, 69, 70, 90, 91
” panelling, if not seasoned, shrinks, 288
” how to prevent splitting, 106
Ohio fire-proof paint, 185
Oil, Arracan, to protect wood from ants, 252
” boiled, to preserve planks of ships, 111
” castor, with cow-dung mortar, 251
” cajeput, to protect wood from ants, 247, 286
” of cedar, to protect wood from worms, 106
” cocoa-nut, to preserve wood, 107
” ” and other substances, 107
” dammer, and other substances, 255
” fish, 108
” ” experiments with, 108
” ” and other substances, 108
” linseed, 106
” ” and other substances, 106, 165, 268, 284, 285
” olive, 106
” of juniper, to prevent worms, 285
” of mustard, to preserve wood, 107
” of spikenard, 106, 285
” of tar; and other substances, 123, 155, 162
” of tar--_see_ Coal Tar
” palm, to preserve wood, 106, 107
” ” and other substances, 123
” paraffin, to cure dry rot, 285
” petroleum, to preserve wood, 109, 157, 169, 262, 287
” ” and sand, 109
” vegetable, best to preserve wood, 106
” whale, 286
” ” renders wood brittle, 106
” ” and other substances, 106, 107
” and other substances, 156, 167
Oils, animal, render wood brittle, 107
Oxford’s patent, 123
Painting, house, described, 199
” ” causes rot, 183, 185, 269
” how to remove from carvings, 270
Paling, rot in, 185
Pallas’ iron and lime process, 117
Panthéon, Paris, dry rot in dome, 42
Parkes’ caoutchouc process, 162
Parry’s (Dr.) suggestion to prevent rot, 156
Passez’s caoutchouc in sulphur process, 162
Pasteur, researches of, 17
Patents, most successful patents, 169
Payne’s patent process, 144, 154, 156, 223, 254
Peat moss, for seasoning wood, 116
Penrose’s report on carvings, St. Paul’s Cathedral, 271
Pepys, Memoirs of, account of rot in ships in, 24
Pering on dry rot, 25
Petersburgh deals, white and yellow, 38, 66
Petroleum oil to prevent rot, 109, 157, 169, 262, 287
Phillips (R.), on seasoning oak, 70
Piles, timber, 23, 96, 219, 221, 223, 226, 228, 285
” ” cased in iron, 229
Pine, yellow, liable to rot, 43
Pitch, 96, 174, 224
” and other substances, 107, 159
Pith of tree, formation of, 4
Pliny, on salt-water seasoning, 72
Polyporus hybridus fungi, 21
Porcher (Dr.), on seasoning wood, 75
Posts, experiments with, 45
” in Norway, how preserved, 173
” burning ends to preserve, 96, 98
” where they decay, 24
” coating, to preserve, 161
Potash, and other substances, 166, 167
Price and Manby’s drying stove, 88
Pringle (Sir J.), on the strength of alum, 119
Pritchard’s report on sea-worms, 156, 233
Processes, rules for successful, 110
” pressure and vacuum, 168
Prussiate of copper (Boucherie’s process), 146
” of iron ” ” 146
Pyroligneous acid, 111, 144, 263
Pyrolignite of iron, 130, 146, 151, 234
” ” and oil of tar, 156
Quassia, 266, 285
” and colocynth, 263
Quatrefages’ experiments, 225, 242
Quicklime, if dry, preserves wood, 116
Railway sleepers, 47, 49, 74, 101, 103, 125, 134, 136, 138, 140,
143, 149, 151, 152, 251, 254
Rance’s experiments with chloride of sodium, 164
Randall (J.), on oxidating wood, 98
Ransome’s silicate of soda process, 156, 227
Rats, how to get rid of, 173
Reid’s vegetable acid process, 111
Remedies for white ants, 286
” for black ants, 287
” for dry rot, 284
” worms in carvings, 286
” ” in piles, 285
Renwick’s vapour of creosote process, 146
Resin, and other substances, 122, 159, 161, 285
Robins, oleaginous vapour process, 157
Rogers (W. J.), the wood carver, 72, 268, 274
Rot, internal causes of, 32
” in timber, how to ascertain, 33, 185
” ” to prevent, 283
” ” to cure, 284
Salt, bay, to preserve ships, 114
” common, to preserve ships, 112
” ” to preserve railway sleepers, 74
” water, lime, &c., to preserve wood, 73, 111
” vessels last long, 114
Saltpetre, to preserve ships, 114
Salts, deliquescent, corrode metals, 112
Sand and coal tar, 284
” and petroleum, 109
” bath, 116
” sea, 113, 181
Sapwood in different woods, 3
Saturating woods to resist beetles, 279
Scott’s (Col.) paint for ants, 253
Sea salt and copperas, 166
” sand, 113, 181
” water, effect of, on iron, 230
” weed, 113
” worms, 203
Seasoning by air, and exposure in stacks, 64
” ” heated, 80
” by extraction of sap, 101
” ” water, fresh, 71
” ” ” salt, 73, 113
” ” ” ” sea-weed, and sea-sand, 115
” ” ” lime, 73, 111
” ” smoke, 91
” ” steaming and boiling, 77
” ” ” charring, 99
” ” gas, 97, 164
” ” sand bath, 116
” ” scorching and charring, 95,97
” ” baking, 79, 81, 86, 88, 94
” oak, 69, 70, 72, 289
” second, 103
Sea-worms, woods which resist, 223
Selenite, experiments with, 119
Shakes in wood, 10, 249, 250
Shaw (Capt. E. M.), on admission of air, 120, 171
Shield’s remedy for white ants, 245, 256
Ships, 99, 111, 112, 114, 116, 117, 194, 251
” dry rot in, 23, 26, 73, 93, 112, 114
Silicate of potash, 155
” of soda, 156, 160, 227
” ” and lime, 160
Silloway (T. W.), on seasoning wood, 75, 92
Silver grain, 6
Size for wood, why required, 197
” and corrosive sublimate, 266
Slating wall to keep out damp, 177
Sleepers, _see_ Railway Sleepers
Smirke (Sir R.), on dry rot, 20, 123
Smith’s solution for wood beetles, 264
Soap, experiments with, 122
” metallic, to preserve wood, 165
” yellow ” ” 165
” and other substances, 253
Society of Arts building, dry rot in, 42
Soda, carbonate of, 155
Soluble glass, 155
Southend pier, attacked by sea-worms, 209
Spores, description of, 15
Stains for woods, 189, 197
Stanmore Cottage, dry rot in floor at, 183
Steam, 145, 168
” --_see_ Seasoning by Steam
Stephenson (Sir M.), on creosoted wood, 134
Stevenson (R.), on timber piles, 205, 217
St. James’s Church, Piccadilly, carvings at, 272, 281
St. Helena, experiments with woods at, 256
St. Mark’s, Venice, rotten curb of dome at, 176
St. Paul’s Cathedral, London, 42, 271, 290
St. Preuve’s steam process, 80
Stove drying, 79, 81, 86, 88, 94
Strength of timber, 11
Strontia, and other substances, 166
Sublimate--_see_ Corrosive Sublimate
Sulphate of copper, 122, 146, 149, 150, 151, 161, 226, 284
” ” and sulphuric acid, 285
” of iron, 154, 157, 284
” ” and other substances, 117, 166, 284
Sulphur, 163
” in other substances, 163, 285
Sulphuric acid, 161, 285
Surinam, groo-groo worms in, 247
Swift’s, Dean, recipe for beetles, 282
Tallow bath for wood, 144
Tar, and other substances, 106, 130, 159, 228, 251, 284
Tarred rope, and lead for piles, 228
Teak oil, to preserve wood from ants, 259
” chips, distilled, 163
Temple of Diana, at Ephesus, built on charred piles, 98
” buildings, London, dry rot in, 124
Tennant’s (Sir E.) account of ants in Ceylon, 246
” ” bees ” 260
Teredo navalis, description of, 212
” --_see_ Worms, Sea
Termites--_see_ Ants, White
Tie-beam, instance of unseasoned, 289
Timber depreciates by keeping too long, 64
Tissier’s hot air process, 102
Toplis’ sulphate of iron process, 157
Tredgold (T.), on seasoning wood, 78, 101, 290
Treenails, 26, 110, 118
Trees, symptoms of decay in, 52
” how to prepare for felling, 61
” when to fell, 53, 54, 55, 58
Trinity College, Cambridge, carvings at, 269, 273
” Oxford ” 269, 273
Truman’s brewery, seasoning casks at, 84
Turpentine prevents rot, 36, 257, 263, 285
” in corrosive sublimate, 115
Uninflammable wood, good process required for, 170, 291
Unseasoned oak panelling, 288
” roof principal, 289
Vaporizing woods, 276
Vapour of creosote process, 145
Venice, built on piles, 23
Vernet’s fire-proof method, 167
Vessels in coal trade last long, 117
” in lime ” 116
” in salt ” 114
Vinegar--_see_ Garlic
Vitriol, blue--_see_ Sulphate of Copper
” green--_see_ Sulphate of Iron
Vitruvius on seasoning wood, 75
Vulliamy (G.), on charring posts, 96
Wade’s suggestions for preserving wood, 119, 122
Wainscot, Crown Riga, 90
” dry rot in, 35, 125
” how to cut oak for, 70
” unseasoned oak for, 289
Wallis’ experiments with beetles, 276
Walnut juice for worms, 263
Warburton’s (H.) opinion of American oak, 40
Warping of boards, 66, 67
Water in wood, 39, 67, 180
” in church, 29
” glass to preserve piles, 226
Watson’s (Dr.) experiments with wood, 67
Westwood’s (Prof.) report on wood beetles, 262
Wet rot, how caused, 14, 28
Wimpole, carvings at, 273
Wood bond decays, 175, 176
” progress of decay in, 19
” (Rev. J.), on worms and ants, 211, 265
Woods best when not painted, 189
” experiments with, 46, 58, 67
” french polished, 192
” white, improved by water seasoning, 72
” which resist beetles, 273
” ” sea-worms, 223
” ” white ants, 249
Woodcutters, 55
” tricks of Indian, 11
” tricks, of, in Ceylon, 114
Woody fibre, formation of, 2, 7
Worms, sea, 203
” how to prevent in wood, 285
Wren (Sir C.), 23, 98, 221, 271
Zinc, chloride of--_see_ Burnett’s Process
” sulphate of, 122
” white oxide of, 226
” and other substances, 165
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“This volume possesses one feature which renders it almost
unique; this feature is the mode in which it is illustrated. It
is not difficult to take a diagram if the instrument is once
set, and the setting with stationary engines is occasionally
easy enough, but circumstances continually arise under which the
young engineer is completely at a loss as to how to obtain a
diagram. All uncertainty will be removed by referring to the book
under consideration: here we have drawings of the arrangements
to be adopted under every conceivable circumstance, drawings, we
may add, illustrating the practice of the best engineers of the
day.”--_Engineer._
* * * * *
_Link-Motion and Expansion Gear Practically Considered._ By N. P. BURGH,
Engineer. _Illustrated with 90 plates and 229 wood engravings_, small
4to, cloth, 30_s._
* * * * *
_The Mechanician and Constructor for Engineers_, comprising Forging,
Planing, Lining, Slotting, Shaping, Turning, Screw Cutting, etc. By
CAMERON KNIGHT. _Containing 96 plates, 1147 illustrations, and 397 pages
of letterpress._ Cheaper edition, cloth, 18_s._
* * * * *
_The Essential Elements of Practical Mechanics; based on the Principle
of Work_, designed for Engineering Students. By OLIVER BYRNE, formerly
Professor of Mathematics, College for Civil Engineers. Third edition,
_illustrated by numerous wood engravings_, post 8vo, cloth, 7_s._ 6_d._
CONTENTS:
Chap. 1. How Work is Measured by a Unit, both with and without
reference to a Unit of Time--Chap. 2. The Work of Living
Agents, the Influence of Friction, and introduces one of
the most beautiful Laws of Motion--Chap. 3. The principles
expounded in the first and second chapters are applied to the
Motion of Bodies--Chap. 4. The Transmission of Work by simple
Machines--Chap. 5. Useful Propositions and Rules.
* * * * *
_The Practical Millwright’s and Engineer’s Ready Reckoner_; or Tables for
finding the diameter and power of cog-wheels, diameter, weight, and power
of shafts, diameter and strength of bolts, etc. By THOMAS DIXON. Fourth
edition, 12mo, cloth, 3_s._
CONTENTS:
Diameter and Power of Wheels--Diameter, Weight, and Power of
Shafts--Multipliers for Steam used Expansively--Diameters and
Strength of Bolts--Size and Weight of Hexagonal Nuts--Speed
of Governors for Steam Engines--Contents of Pumps--Working
Barrels--Circumferences and Areas of Circles--Weight of Boiler
Plates--French and English Weights and Measures, etc.
* * * * *
_The Principles of Mechanics and their Application to Prime Movers, Naval
Architecture, Iron Bridges, Water Supply, etc._ By W. J. MILLAR, C.E.,
Secretary to the Institution of Engineers and Shipbuilders, Scotland.
Crown 8vo, cloth, 4_s._ 6_d._
* * * * *
_A Practical Treatise on Mill-gearing, Wheels, Shafts, Riggers, etc._;
for the use of Engineers. By THOMAS BOX. Crown 8vo, cloth, _with 11
plates_, second edition, 7_s._ 6_d._
* * * * *
_Mining Machinery_: a Descriptive Treatise on the Machinery, Tools, and
other Appliances used in Mining. By G. G. ANDRÉ, F.G.S., Assoc. Inst.
C.E., Mem. of the Society of Engineers. Royal 4to, uniform with the
Author’s Treatise on Coal Mining, containing 182 _plates_, accurately
drawn to scale, with descriptive text, in 2 vols., cloth, 3_l._ 12_s._
CONTENTS:
Machinery for Prospecting, Excavating, Hauling, and
Hoisting--Ventilation--Pumping--Treatment of Mineral Products,
including Gold and Silver, Copper, Tin, and Lead, Iron, Coal,
Sulphur, China Clay, Brick Earth, etc.
* * * * *
_The Pattern Makers Assistant_; embracing Lathe Work, Branch Work, Core
Work, Sweep Work, and Practical Gear Construction, the Preparation and
Use of Tools, together with a large collection of Useful and Valuable
Tables. By JOSHUA ROSE, M.E. With 250 _illustrations_. Crown 8vo, cloth,
10_s._ 6_d._
* * * * *
_The Science and Art of the Manufacture of Portland Cement_, with
observations on some of its constructive applications, _with numerous
illustrations_. By HENRY REID, C.E., Author of ‘A Practical Treatise on
Concrete,’ etc., etc. 8vo, cloth, 18_s._
* * * * *
_The Draughtsman’s Handbook of Plan and Map Drawing_; including
instructions for the preparation of Engineering, Architectural, and
Mechanical Drawings. With _numerous illustrations in the text, and 33
plates (15 printed in colours)_. By G. G. ANDRÉ, F.G.S., Assoc. Inst.
C.E. 4to, cloth, reduced to 9_s._
CONTENTS:
The Drawing Office and its Furnishings--Geometrical
Problems--Lines, Dots, and their Combinations--Colours, Shading,
Lettering, Bordering, and North Points--Scales--Plotting--Civil
Engineers’ and Surveyors’ Plans--Map Drawing--Mechanical and
Architectural Drawing--Copying and Reducing Trigonometrical
Formulæ, etc., etc.
* * * * *
_The Railway Builder_: a Handbook for Estimating the Probable Cost of
American Railway Construction and Equipment. By WILLIAM J. NICOLLS, Civil
Engineer. _Illustrated_, full bound, pocket-book form, 7_s._ 6_d._
* * * * *
_Rock Blasting_: a Practical Treatise on the means employed in Blasting
Rocks for Industrial Purposes. By G. G. ANDRÉ, F.G.S., Assoc. Inst. C.E.
_With 56 illustrations and 12 plates_, 8vo, cloth, 10_s._ 6_d._
* * * * *
_Surcharged and different Forms of Retaining Walls._ By J. S. TATE. Cuts,
8vo, sewed, 2_s._
* * * * *
_A Treatise on Ropemaking as practised in public and private Rope-yards_,
with a Description of the Manufacture, Rules, Tables of Weights, etc.,
adapted to the Trade, Shipping, Mining, Railways, Builders, etc. By R.
CHAPMAN, formerly foreman to Messrs. Huddart and Co., Limehouse, and late
Master Ropemaker to H.M. Dockyard, Deptford. Second edition, 12mo, cloth,
3_s._
* * * * *
_Sanitary Engineering; a Series of Lectures given before the School of
Engineering, Chatham._ Division I. Air.--Division II. Water.--Division
III. The Dwelling.--Division IV. The Town and Village.--Division V. The
Disposal of Sewage. Copiously illustrated. By J. BAILEY DENTON, C.E.,
F.G.S., Honorary Member of the Agricultural Societies of Norway, Sweden,
and Hanover, and Author of the ‘Farm Homesteads of England,’ ‘Village
Sanitary Economy,’ ‘Storage of Water,’ ‘Sewage Farming,’ etc. Royal 8vo,
cloth, 25_s._
* * * * *
_Sanitary Engineering_: a Guide to the Construction of Works of Sewerage
and House Drainage, with Tables for facilitating the calculations of
the Engineer. By BALDWIN LATHAM, C.E., M. Inst. C.E., F.G.S., F.M.S.,
Past-President of the Society of Engineers. Second edition, _with
numerous plates and woodcuts_, 8vo, cloth, 1_l._ 10_s._
* * * * *
_A Practical Treatise on Modern Screw-Propulsion._ By N. P. BURGH,
Engineer. _Illustrated with 52 large plates and 103 woodcuts_, 4to,
half-morocco, 2_l._ 2_s._
* * * * *
_Screw Cutting Tables for Engineers and Machinists_, giving the values of
the different trains of Wheels required to produce Screws of any pitch,
calculated by LORD LINDSAY, M.P., F.R.S., F.R.A.S., etc. Royal 8vo,
cloth, oblong, 2_s._
* * * * *
_Screw Cutting Tables_, for the use of Mechanical Engineers, showing the
proper arrangement of Wheels for cutting the Threads of Screws of any
required pitch, with a Table for making the Universal Gas-pipe Threads
and Taps. By W. A. MARTIN, Engineer. Second edition, royal 8vo, oblong,
cloth, 1_s._
* * * * *
_Treatise on Valve-Gears_, with special consideration of the Link-Motions
of Locomotive Engines. By Dr. GUSTAV ZEUNER. Third edition, revised and
enlarged, translated from the German, with the special permission of the
author, by MORITZ MÜLLER. _Plates_, 8vo, cloth, 12_s._ 6_d._
* * * * *
_Cleaning and Scouring_: a Manual for Dyers, Laundresses, and for
Domestic Use. By S. CHRISTOPHER. 18mo, sewed, 6_d._
* * * * *
_A Treatise on a Practical Method of Designing Slide-Valve Gears by
Simple Geometrical Construction_, based upon the principles enunciated in
Euclid’s Elements, and comprising the various forms of Plain Slide-Valve
and Expansion Gearing; together with Stephenson’s, Gooch’s, and Allan’s
Link-Motions, as applied either to reversing or to variable expansion
combinations. By EDWARD J. COWLING WELCH, Memb. Inst. Mechanical
Engineers. Crown 8vo, cloth. 6_s._
* * * * *
_The Slide Valve practically considered._ By N. P. BURGH, Engineer. Ninth
edition, _with 88 illustrations_, crown 8vo, cloth, 5_s._
* * * * *
_A Pocket-Book for Boiler Makers and Steam Users_, comprising a variety
of useful information for Employer and Workman, Government Inspectors,
Board of Trade Surveyors, Engineers in charge of Works and Slips, Foremen
of Manufactories, and the general Steam-using Public. By MAURICE JOHN
SEXTON. Royal 32mo, roan, gilt edges, 5_s._
* * * * *
_Modern Compound Engines_; being a Supplement to Modern Marine
Engineering. By N. P. BURGH, Mem. Inst. Mech. Eng. _Numerous large plates
of working drawings_, 4to, cloth, 18_s._
The following Firms have contributed Working Drawings of their
best and most modern examples of Engines fitted in the Royal
and Mercantile Navies: Messrs. Maudslay, Rennie, Watt, Dudgeon,
Humphreys, Ravenhill, Jackson, Perkins, Napier, Elder, Laird,
Day, Allibon.
* * * * *
_A Practical Treatise on the Steam Engine_, containing Plans and
Arrangements of Details for Fixed Steam Engines, with Essays on the
Principles involved in Design and Construction. By ARTHUR RIGG, Engineer,
Member of the Society of Engineers and of the Royal Institution of Great
Britain. Demy 4to, _copiously illustrated with woodcuts and 96 plates_,
in one Volume, half-bound morocco, 2_l._ 2_s._; or cheaper edition,
cloth, 25_s._
This work is not, in any sense, an elementary treatise, or
history of the steam engine, but is intended to describe examples
of Fixed Steam Engines without entering into the wide domain of
locomotive or marine practice. To this end illustrations will be
given of the most recent arrangements of Horizontal, Vertical,
Beam, Pumping, Winding, Portable, Semiportable, Corliss, Allen,
Compound, and other similar Engines, by the most eminent
Firms in Great Britain and America. The laws relating to the
action and precautions to be observed in the construction of
the various details, such as Cylinders, Pistons, Piston-rods,
Connecting-rods, Cross-heads, Motion-blocks, Eccentrics,
Simple, Expansion, Balanced, and Equilibrium Slide-valves, and
Valve-gearing will be minutely dealt with. In this connection
will be found articles upon the Velocity of Reciprocating Parts
and the Mode of Applying the Indicator, Heat and Expansion of
Steam Governors, and the like. It is the writer’s desire to draw
illustrations from every possible source, and give only those
rules that present practice deems correct.
* * * * *
BARLOW’S _Tables of Squares, Cubes, Square Roots, Cube Roots, Reciprocals
of all Integer Numbers up to 10,000_. Post 8vo, cloth, 6_s._
* * * * *
CAMUS (M.) _Treatise on the Teeth of Wheels_, demonstrating the best
forms which can be given to them for the purposes of Machinery, such
as Mill-work and Clock-work, and the art of finding their numbers,
translated from the French. Third edition, carefully revised and
enlarged, with details of the present practice of Millwrights, Engine
Makers, and other Machinists. By ISAAC HAWKINS. _Illustrated by 18
plates_, 8vo, cloth, 5_s._
* * * * *
_A Practical Treatise on the Science of Land and Engineering, Surveying,
Levelling, Estimating Quantities, etc._, with a general description of
the several Instruments required for Surveying, Levelling, Plotting, etc.
By H. S. MERRETT. 41 _fine plates with Illustrations and Tables_, royal
8vo, cloth, third edition, 12_s._ 6_d._
PRINCIPAL CONTENTS:
Part 1. Introduction and the Principles of Geometry. Part 2. Land
Surveying; comprising General Observations--The Chain--Offsets
Surveying by the Chain only--Surveying Hilly Ground--To
Survey an Estate or Parish by the Chain only--Surveying
with the Theodolite--Mining and Town Surveying--Railroad
Surveying--Mapping--Division and Laying out of Land--Observations
on Enclosures--Plane Trigonometry. Part 3. Levelling--Simple
and Compound Levelling--The Level Book--Parliamentary Plan
and Section--Levelling with a Theodolite--Gradients--Wooden
Curves--To Lay out a Railway Curve--Setting out Widths. Part
4. Calculating Quantities generally for Estimates--Cuttings
and Embankments--Tunnels--Brickwork--Ironwork--Timber
Measuring. Part 5. Description and Use of Instruments in
Surveying and Plotting--The Improved Dumpy Level--Troughton’s
Level--The Prismatic Compass--Proportional Compass--Box
Sextant--Vernier--Pantagraph--Merrett’s Improved
Quadrant--Improved Computation Scale--The Diagonal
Scale--Straight Edge and Sector. Part 6. Logarithms of
Numbers--Logarithmic Sines and Co-Sines, Tangents and
Co-Tangents--Natural Sines and Co-Sines--Tables for Earthwork,
for Setting out Curves, and for various Calculations, etc., etc.,
etc.
* * * * *
_Saws: the History, Development, Action, Classification, and Comparison
of Saws of all kinds._ By ROBERT GRIMSHAW. With 220 _illustrations_, 4to
cloth, 12_s._ 6_d._
* * * * *
_A Guide for the Electric Testing of Telegraph Cables._ By Capt. V.
HOSKIŒR, Royal Danish Engineers. With _illustrations_. Second edition,
crown 8vo, cloth, 4_s._ 6_d._
* * * * *
_Laying and Repairing Electric Telegraph Cables._ By Capt. V. HOSKIŒR,
Royal Danish Engineers. Crown 8vo, cloth, 3_s._ 6_d._
* * * * *
_A Pocket-Book of Practical Rules for the Proportions of Modern Engines
and Boilers for Land and Marine purposes._ By N. P. BURGH. Seventh
edition, royal 32mo, roan, 4_s._ 6_d._
Details of High-Pressure Engine, Beam Engine, Condensing, Marine
Screw Engines, Oscillating Engines, Valves, etc., Land and
Marine Boilers, Proportions of Engines produced by the Rules,
Proportions of Boilers, etc.
* * * * *
_Table of Logarithms of the Natural Numbers, from_ 1 to 108,000. By
CHARLES BABBAGE, Esq., M.A. Stereotyped edition, royal 8vo, cloth, 7_s._
6_d._
To ensure the correctness of these Tables of Logarithms, they
were compared with Callett’s, Vega’s, Hutton’s, Briggs’,
Gardiner’s, and Taylor’s Tables of Logarithms, and carefully read
by nine different readers; and further, to remove any possibility
of an error remaining, the stereotyped sheets were hung up in the
Hall at Cambridge University, and a reward offered to anyone who
could find an inaccuracy. So correct are these Tables, that since
their first issue in 1827 no error has been discovered.
* * * * *
_The Steam Engine considered as a Heat Engine_: a Treatise on the Theory
of the Steam Engine, illustrated by Diagrams, Tables, and Examples from
Practice. By JAS. H. COTTERILL, M.A., Professor of Applied Mechanics in
the Royal Naval College, 8vo, cloth, 12_s._ 6_d._
* * * * *
_The Practice of Hand Turning in Wood, Ivory, Shell, etc._, with
Instruction for Turning such Work in Metal as maybe required in the
Practice of Turning in Wood, Ivory, etc., also an Appendix on Ornamental
Turning. (A book for beginners). By FRANCIS CAMPIN. Second edition, _with
wood engravings_, crown 8vo, cloth, 6_s._
CONTENTS:
On Lathes--Turning Tools--Turning Wood--Drilling--Screw
Cutting--Miscellaneous Apparatus and Processes--Turning
Particular Forms--Staining--Polishing--Spinning
Metals--Materials--Ornamental Turning, etc.
* * * * *
_Health and Comfort in House Building, or Ventilation with Warm Air
by Self-Acting Suction Power_, with Review of the mode of Calculating
the Draught in Hot-Air Flues, and with some actual Experiments. By J.
DRYSDALE, M.D., and J. W. HAYWARD, M.D. Second edition, with Supplement,
demy 8vo, _with plates,_ cloth, 7_s._ 6_d._
* * * * *
_Treatise on Watchwork, Past and Present._ By the Rev. H. L. NELTHROPP,
M.A., F.S.A. _Numerous illustrations_, crown 8vo, cloth, 6_s._ 6_d._
CONTENTS:
Definitions of Words and Terms used in
Watchwork--Tools--Time--Historical Summary--On Calculations of
the Numbers for Wheels and Pinions; their Proportional Sizes,
Trains, etc.--Of Dial Wheels, or Motion Work--Length of Time
of Going without Winding up--The Verge--The Horizontal--The
Duplex--The Lever--The Chronometer--Repeating Watches--Keyless
Watches--The Pendulum, or Spiral Spring--Compensation--Jewelling
of Pivot Holes--Clerkenwell--Fallacies of the Trade--Incapacity
of Workmen--How to Choose and Use a Watch, etc.
* * * * *
_Now in Course of Publication._
To be completed in about 30 Monthly Parts, each Part containing 64 pp.,
with _numerous illustrations_, super-royal 8vo, price 2_s._; or in 5
Divisions, cloth, price 13_s._ 6_d._ each.
DIVISIONS I., II, & III., NOW READY.
SPONS’ ENCYCLOPÆDIA OF THE INDUSTRIAL ARTS, MANUFACTURES, AND COMMERCIAL
PRODUCTS.
* * * * *
_Now in Course of Publication._
To be completed in about 18 Monthly Parts, each Part containing 64 pp.,
with _numerous illustrations_, super-royal 8vo, price 2_s._; or in 3
Divisions, cloth, price 13_s._ 6_d._ each.
DIVISIONS I. AND II. NOW READY.
A SUPPLEMENT TO SPONS’ DICTIONARY OF ENGINEERING,
Civil, Mechanical, Military, and Naval.
EDITED BY ERNEST SPON, MEMB. SOC. ENGINEERS.
* * * * *
London: E. & F. N. SPON, 16, Charing Cross.
New York: 446, Broome Street.
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