THE
USEFUL ARTS
EMPLOYED IN
THE CONSTRUCTION OF
DWELLING HOUSES.
_THE SECOND EDITION._
LONDON:
JOHN W. PARKER, WEST STRAND.
MDCCCLI.
LONDON:
SAVILL AND EDWARDS, PRINTERS,
CHANDOS STREET.
PREFACE.
The dwellings of mankind, at first rude and simple in the extreme,
increase in complexity as their inhabitants advance in civilization.
Primitive dwellings are scarcely distinguished by signs of superior
skill or sagacity above the holes and nests of the lower animals. The
hut of the Hottentot may be considered as an inverted nest, and it is
certainly not more ingenious than the nests of many birds; but where
man constructs such a habitation for himself, he is invariably in a
low state of civilization. The wants of the bird are few and simple,
and the nest is a temporary abode annually constructed and annually
deserted: the wants of man, in a state of nature, are almost as
limited, and thus the Hottentot’s hut affords him as good a nest as he
desires. But when he steps forth into the rank which the Creator has
destined him to fill; when he feels that he is a responsible being, the
creation of an Almighty Power to whom worship is due; when he finds
that the productions of the earth are capable of being rendered useful
to him by the exercise of his ingenuity, and that his own mental powers
are capable of being developed by communion with, and by the assistance
of his fellow-men;--then the hut--the inverted nest--is no longer equal
to his necessities. He makes implements, and he must have a place
to shelter them; he cultivates grain, and he requires a store-house
for it; he collects and records the thoughts and the wisdom of his
predecessors, and he must have a roof to cover these precious mementos:
unlike other animals, he requires _fire_ for the preparation of the
greater portion of his food; and his fire, as well as his utensils,
must be well defended from without:--in short, his wants are so
multiplied by the cultivation of his reason, that a _house_ has become
necessary to him. The beasts of the field and the birds of the air have
certain natural instincts given to them which guide them through life,
and are perpetuated in their offspring; the same routine goes on race
after race without the operation of what we term improvement. Not so
with man: he is a progressive being: he steps forth beyond the limits
of mere animal life, and has a mental existence, with wants created
by it, and depending on it; wants which are not known to him when
considered as a mere animal.
The building of houses has in all ages formed part of the employment of
man as he advanced from a state of mere barbarism to one of comparative
civilization. In devoting this little volume, therefore, to the subject
of the Application of the Useful Arts to the construction of Dwellings,
it is necessary to set a limit to so large a subject. A wigwam is
a house,--so is a palace, and examples of every possible gradation
between the two might be given. In order, then, to avoid the seeming
ambition of grasping the whole of this extensive subject we shall not
travel out of our own country; nor shall we ascend to the very highest,
or descend to the very lowest class of dwellings; but shall describe
the principal arts concerned in building a modern English house of
moderate rank. In so doing, we shall treat the subject under a few
simple heads, classified mainly according to the materials employed.
[Illustration]
CONTENTS.
PREFACE p. iii
CHAPTER I. THE WALLS--STONE AND STONE-WORK.
Introduction, 9--Principal varieties of building stone,
10--On quarrying stone, 13--The application of electricity to the
blasting of rocks, 17--Sawing the stones for the mason,
22--The processes of stone-masonry, 22.
CHAPTER II. ON THE DURABILITY OF STONE BUILDINGS.
On the choice of a stone for building purposes, 27--Examination of a
variety of buildings as to the durability of the stone employed
therein, 28--The stone for the new Houses of Parliament--how chosen,
32--An easy method of determining whether a stone will resist the
action of frost, 33--Directions for practising this method, 38.
CHAPTER III. THE WALLS--BRICKS AND BRICK-WORK.
Early use of bricks, 40--Floating bricks, 41--Making bricks by hand,
42--Varieties of bricks, 44--Tiles, 45--Making bricks and tiles by
machinery, 46--The Marquis of Tweeddale’s method, 46--Another method,
47--The processes of bricklaying, 48--Mortar, 48--Defects of modern
brick houses, 52.
CHAPTER IV. THE ROOF--SLATES AND OTHER ROOF COVERINGS.
Slate quarries, 54--The process of slating, 57--Paper roofs, 58--Their
advantages, 60--Terrace roofs, 61--Asphalte roofs, 61--Scotch fir
roofs, 61--Iron roofs, 62--Zinc and other metallic roofs, 63--Thatch
roofs, 63.
CHAPTER V. THE WOOD-WORK--GROWTH AND TRANSPORT OF TIMBER.
The oak as a timber tree, 66--The two chief varieties of oak,
67--Teak, 69--The fir and pine as timber trees, 69--The Norway spruce
fir, 70--The Scotch fir, 73--Transport of timber from the forests,
77--Historical notices, 78--Rafts on the Rhine, 80--The slide of
Alpnach, 81--Cutting the Norway deals, 83--The cutting and transport
of Canadian timber, 83--Lumberers, 83--Saw-mills, 84--Rafts on the
American rivers, 85--Miscellaneous kinds of timber, 86--Fancy woods,
87.
CHAPTER VI. THE WOOD-WORK--CARPENTRY.
Sawing timber, 89--Scarfing or joining timber, 89--Trussing or
strengthening, 90--Details of roof, 92--The mortise and other joints,
93--Distinction between carpentry and joinery, 95--The tools employed,
96--Glue, 98--A window sash, as an example of joiner’s work, 99--A
second example of joiner’s work, 100.
CHAPTER VII. THE FIRE-PLACE.
Open fire-places, 102--Philosophy of a chimney, 103--Defects of open
fires, 103--Remedies for some of these defects, 106--The register
stove, 108--Smoky chimneys, 108--Causes of, and cure, 108--Close
stoves, 111--The German stove, 112--Dr. Arnott’s stove,
113--Objections thereto, 115--Warming buildings by heated air,
116--The Russian stove, 116--Other methods, 117--Sir Stewart
Monteith’s stove, 118--Warming buildings by steam, 118--Warming
buildings by hot-water, 119--The high-pressure system, 120.
CHAPTER VIII. THE WINDOWS AND LEAD-WORK.
Introduction of glass windows, 122--The manufacture of crown glass,
122--The manufacture of plate glass, 129--Cutting glass, 133--The
process of glazing, 134--Sheet lead for roofs and cisterns, 135--Lead
pipes, 136--The process of plumbing, 136--Solder or cement for metals,
139--Autogenous soldering, 140--Its advantages, 144.
CHAPTER IX. THE INTERIOR--PLASTERING AND PAPER-HANGING.
Plastering walls and ceilings, 148--Plaster and papier-maché ornaments
for rooms, 149--Whitewashing and stuccoing, 150--Origin of
paper-hangings, 150--The manufacture of paper-hangings, 151--Stencil,
washable, and flock paper-hangings, 153--The process of paper-hanging,
155.
CHAPTER X. THE INTERIOR--PAINTING AND GILDING.
Reasons for painting a house, 158--Materials used in house painting,
158--Preparing the paint, 160--The process of painting, 160--Graining
and marbling, 162--Gilding as an interior decoration, 164--The process
of burnish-gilding, 165--The process of oil-gilding, 167--Gilding
enriched ornaments, 168.
CHAPTER XI. A MODEL DWELLING-HOUSE.
The late Sir John Robison’s house at Edinburgh, 170--The Interior,
170--Warming, 170--Ventilating, 171--Lighting, 172--Gas cooking
apparatus, 172--Flues, 173--Interior decorations by Mr. Hay,
173--A beau-ideal English villa, 174--Situation, 175--Style,
175--Arrangement of the interior, 176--The principal apartments,
bed-rooms, &c., 177--The kitchen, 179.
CHAPTER XII. FIRE-PROOF HOUSES.
Hartley’s method of making houses fire-proof, 181--Earl Stanhope’s
methods, 181--Pambœuf’s method, 183--Fire-proof paint,
184--Experimental trials, 184--Leconte’s method, 185--Varden’s method,
186--Frost’s method, 186--Loudon’s methods, 187--General remarks, 188.
CHAPTER XIII. MISCELLANEOUS PROCESSES.
Manufacture of nails, 188--Locks and keys, 188--Stoves and grates,
190--Bells, 190--Brass handles, ornaments, &c., 191--Preservation of
timber, 191--Various methods, 193--Kyanizing, 194--Soluble glass,
194--Its uses in preserving timber, &c., 197--Veneering, 198--Brunel’s
method of cutting veneers, 198--Russian method, 199--The process of
veneering, 199--Manufacture of glue, 201--The house decorator of
Italy, 201--Fresco painting as applied to the decoration of houses,
206--Nature and difficulties of the art, 207--Notices of the ancient
custom of decorating walls, 208--The practice of fresco painting,
208--The Cartoon, 209--The preparation of the wall, 210--The process
of painting, 210--The colours and implements, 211--A fresco painter at
work described, 212--General remarks on fresco painting, 214.
CONCLUSION 215
The Useful Arts Employed in the Construction of Dwelling-Houses.
CHAPTER I.
THE WALLS. STONE AND STONE-WORK.
The material mainly employed in the construction of buildings depends
partly on the purpose for which the buildings are intended, and
still more, perhaps, on the prevailing geological character of the
surrounding country. In such a place as London, where there is an
immense mass of tenacious clay beneath the vegetable soil, and where
solid stone is not to be had, except by bringing it, at a great
expense, from a distance of many miles, clay seems to be the natural
material for dwellings; and thus we find that almost all the London
houses are built of brick formed of clay. In other parts of Great
Britain, such as Glasgow or Edinburgh, the case is very different; for,
in those places, clay is scarce, and stone is plentiful. There are
quarries not far from Edinburgh, and others within the very precincts
of Glasgow, where an abundant supply of good building-stone is obtained
at a very low rate. Hence it follows as a natural consequence, that
the houses in those two cities exhibit a large proportion of stone
structures; so much so, indeed, that an inhabitant of London, who is
accustomed to see stone appropriated only to large important public
buildings, is apt to imagine that the houses in the two northern cities
must necessarily be very costly. This is by no means certain, however,
for the builders in each city make use of those materials which may be
most available.
Whether stone form the main portion of the walls of a house, as in the
cases just named, or whether it is only used in smaller degree, as in
London houses, the operations by which it is worked and fitted are
pretty much the same; and we will therefore devote this chapter to a
brief description of the principal kinds of building-stone, followed by
an outline of the _Mason’s_ operations.
Principal Varieties of Building-stone.
_Granites_ are rocks which have been formed by the union of three
different minerals in a state of fusion; these, on cooling, have
crystallized and become distinct from each other in the mass. It is on
the varied proportions in which these three constituents are combined,
that the colour, hardness, durability, and beauty of the various
granites depend. The light-red and rose-coloured granites contain the
felspar in greatest abundance and in the largest crystals; but this
mineral varies in hue from the purest white to nearly black; it is the
ingredient most acted on by the atmosphere; the rock, therefore, which
abounds in it, though it may be more beautiful to the eye, and more
easily worked at first, is not so durable as that which contains it
in smaller crystals, and with a larger proportion of _quartz_. It is
to this last-named mineral that granite owes the sparkling appearance
which it presents when the sun shines on it; quartz is the hardest and
most imperishable of the three minerals which form the granite-rock.
The third, _mica_, is distinguishable from the other two by its satiny,
shining, dark hue, and is very apparent in the coarse-grained, handsome
stone of our own country, brought from Cornwall.
When the felspar is replaced by another mineral called _hornblende_,
the stone is of a dark-greenish hue, and the component parts are in
a finer form and less distinguishable from each other. The Aberdeen
granite is an example of this kind, which is more durable than the
former, though not so pleasing to the eye.
Granite occurs in all the larger mountain-ranges, and in isolated
masses in every country; not being a stratified rock, and being
excessively hard, it is difficult to quarry and get out in manageable
masses. Blasting with gunpowder is the mode usually employed in this
country; the pieces detached by this means are hewn roughly into form
on the spot by a small pickaxe. Aberdeen granite is quarried by cutting
a deep line some yards long, and placing strong iron wedges at equal
distances in this line; these wedges are struck in succession by heavy
hammers till the mass splits down. This, or analogous modes, may always
be employed when the rock approaches a slaty or stratified structure,
as is the case with some nearly related to granite. Another method
of detaching masses of rock, is by driving wooden wedges into a deep
fissure, either natural or artificial; the wedges are then wetted, and
the consequent expansion of the wood bursts the rock asunder.
As granite has always to be brought from a great distance to the spot
where it is wanted, because its natural localities are far from the
places where edifices are usually constructed, and also on account of
its hardness, this rock is only used for important buildings, such
as bridges, markets, churches, &c., and not commonly even for these.
London and Waterloo bridges, Covent Garden and Hungerford markets, and
the York column in Pall Mall, are instances of its use in London.
The principal kinds of stone used in building are the LIMESTONES, or
_calcareous rocks_ of the geologist; of these it would be useless
to describe or enumerate more than a few. In our own country, the
_Portland stone_, so called from its principal quarries being in
Portland Island, in Dorsetshire, holds the first rank, and is that
almost exclusively used in London for building, and for the ornamental
parts of edifices. It unites the qualities of being easily sawn and
worked, when lately quarried, and of subsequently hardening by exposure
to the air; it is close and even in its texture, admitting of being
wrought into delicate work, and receiving a very smooth surface, which
it will retain for a considerable period, though it is surpassed in
durability by many other rocks. It is said that the Banquetting-house,
Whitehall, was the first building in London in which this stone was
employed. St. Paul’s, Westminster and Blackfriars’ bridges, Newgate,
and, indeed, most of the public buildings of the metropolis, are
examples of its use.
_Bath-stone_, so called from its being entirely used in the
neighbourhood of that city, is softer and far less durable than the
preceding. When recently quarried, it may be sawn with a toothed
saw, like timber, and can be carved with the greatest facility into
the richest ornaments; hence it is often employed, and, if sheltered
from the weather, is well adapted for such purposes, from its rich,
even cream colour; but though it hardens considerably by exposure,
it is acted upon, after a time, by the air, so as to render it very
perishable. The restoration of Henry the Seventh’s Chapel, Westminster,
is, unfortunately, made with this stone.
The two preceding, and many others, distinguished by names according
to the principal localities, as _Oxford_-stone, _Ketton_-stone,
&c., belong to what geologists term the _Oolitic_ formation, from
the resemblance of some kinds of the rock to fishes’ roe, which is
observable in that we have last mentioned. They all agree in their
principal qualities.
_Purbeck-stone_, also from Dorsetshire, is used for steps, paving,
door-sills, and copings; it is coarser, harder, and less uniform in
texture than the foregoing, and not, therefore, calculated for fine
buildings, except for the purposes we have specified.
_Yorkshire-stone_ resembles the last; it is used for the same purposes,
but especially for paving. The greatest part of the foot-paths in the
streets of London are laid with this or the preceding.
_Rag-stone_ is obtained from quarries on the banks of the Thames,
Medway, &c. It was the stone chiefly used for building in ancient
London, and a great deal is still used for paving.
The lower _chalk_, which is of a grey colour, and contains masses of
flint, was formerly much employed for building in the south-western
counties of England; its good qualities are proved by the perfect state
of many old churches in that part of the kingdom, which are known to be
from seven to nine hundred years old. It is now only sparingly used in
farm-building and cottages, but it is consumed in vast quantities to
burn into lime for mortar and other purposes, and as a manure.
Belonging to the same family of calcareous rocks, and next in utility
to those we have just enumerated, though far surpassing them in beauty
and value, stand the endless varieties of _Marbles_, essentially
characterized by their crystalline texture, superior hardness, and by
the absence of shells or organic remains found so abundantly in all
other limestones. The name of marble is, however, popularly given to
many stones not possessing these characters, but which are hard enough
to be susceptible of a high polish, and are ornamental when so treated.
In this country the finer kinds of real marble are only sparingly
employed in the decorative departments of architecture, such as, for
chimney-pieces, slabs, hearths, capitals of columns in halls, saloons,
monuments, &c. The secondary kinds are also employed for similar
purposes, but more abundantly. The cold white statuary marble is not
adapted for out-of-door use in our foggy and cloudy climate, under the
influence of which it would soon become dingy and disagreeable, as is
proved by the total failure in the effect of the little triumphal arch
erected before Buckingham Palace. In Italy many ancient and modern
edifices are faced with white marble, and in that clear and pure
atmosphere they retain the beauty of the material for ages. The use to
which the finest marbles of Greece and Italy are applied in sculpture,
is familiar to every one.
The last class of rocks employed in building, in those localities where
they occur, are the _Sandstones_, silex, or flint, in finely-comminuted
particles agglutinated together, being their principal ingredient; they
constitute excellent building-stone, and are abundantly used as such in
the West of England.
On Quarrying Stone.
A quarry is an excavation made in the ground, or among rocks, for the
purpose of extracting stone for building, or for sculpture. The name
appears to have originated in the circumstance that the stones, before
they are removed to a distance, are first _quadrated_, or formed into
rectangular blocks.
The following may be taken as an example of the general operations of
quarrying building-stones. If the stone be vertically below the surface
of the ground, the quarrymen first remove the earth and surface soil,
and then dig a perpendicular shaft, or pit, to afford access to the
stone; but if, as frequently happens, the stone be within the flank of
a hill, or mountain, the quarrymen excavate horizontal galleries into
the hill, leaving pillars here and there to support the superincumbent
mass. Supposing a large quarry about to be opened beneath the soil, the
earth is first removed, and then a sort of inferior stone called “rag,”
which generally lies between the soil and the good stone beneath. Large
masses of available stone generally consist of distinct strata lying
close together in a kind of cemented bulk, and the contiguous surfaces
forming _cleavages_, greatly assist the quarrymen in detaching blocks
from the mass. The block is always more easily separated in a direction
parallel to these planes of cleavage than in any other direction, and
the operations are, therefore, guided by this circumstance. The workmen
drive a series of iron wedges into the mass of stone parallel to the
cleavage-planes; and, after a few blows, a portion of the mass becomes
separated in that direction. They then measure off a portion equal to
the intended length and breadth of the stone, and drive their iron
wedges similarly in these directions, by which the piece is entirely
severed from the rocky mass. The cleavage-planes vary interminably in
direction, so that the quarrymen have to work in various positions,
according to the direction of stratification. The operations are more
easily conducted when the cleavage-planes are vertical, than in any
other direction. After the blocks have been severed, they are brought
to an irregularly square shape, by means of a tool called a _kevel_;
and are finally hoisted by cranes on to low trucks, and conveyed on
tram-ways out of the quarry; or else are hoisted to the surface of the
quarry at once, if the depth render that plan necessary.
In quarrying sandstone, and those rocks which consist of regular
layers, the pick, the wedge, the hammer, and the pinch, or lever, are
the chief tools. But for many kinds of limestone, and for greenstone
and basalt, recourse is had to the more violent and irregular effects
of gunpowder. Indeed, some of the primitive rocks, such as granite,
gneiss, and sienite, could scarcely be torn asunder by any other means.
The great objection to blasting by gunpowder is, that the blocks are
broken irregularly, and much of the stone is wasted; but it has the
advantage of being simple in its application, and powerful in its
effects. The grains of powder are suddenly converted into a permanently
elastic air, occupying about four hundred and seventy-two times more
space than their own bulk. The elastic fluid expands with a velocity
calculated at the rate of about ten thousand feet per second; and its
pressure or force, when thus expanding, has been estimated as equal to
one thousand atmospheres, that is, one thousand times greater than the
atmospheric pressure upon a base of the same extent. By applying this
product to a square inch, upon which the atmosphere exerts a pressure
of about fifteen pounds, the elastic fluid of the gunpowder will be
found, at the moment of the explosion, to exert a force equivalent to
six tons and a half upon the square inch of surface exposed to it; and
that with a velocity which the imagination can hardly follow.
[Illustration]
In boring a rock preparatory to blasting, it is necessary to consider
the nature of the stone, and the inclination or dip of the strata, in
order to decide upon the diameter, the depth, and direction of the hole
for the gunpowder. The diameter of the hole may vary according to the
nature of the rock, from half an inch to two and a half inches; and the
depth from a few inches to as many feet; the direction may vary to all
the angles from the perpendicular to the horizontal. The tools used
in this operation are very simple. The chisel, or _jumper_, as it is
called, varies in size according to the work to be performed, and its
edge is more or less pointed to suit the hardness of the rock to be
bored. If the hole is to be small and not deep, it may be bored by a
single person; with one hand he manages the chisel, which he turns at
every blow so as to cross the previous cut, and with the other hand he
strikes it with a hammer of six or eight pounds’ weight, occasionally
clearing out the hole by means of a _scraper_. But when the hole is
large and deep, one man in a sitting posture directs the jumper, pours
water into the hole, and occasionally cleans it out, while two or three
men, with hammers of ten or twelve pounds’ weight, strike successive
blows upon the jumper, until the rock is perforated to the required
depth. To prevent annoyance to the workmen, a small rope of straw or
hemp is twisted round the jumper, and made to rest in the orifice of
the hole. When the holes are to be made to a greater depth than about
thirty inches, it is common to use a chisel from six to eight feet
in length, pointed at both ends, having a bulbous part in the middle
for the convenience of holding it; it thus becomes a kind of double
jumper, and is used without a hammer, with either end put into the
hole at pleasure. The workmen holding this jumper by the bulbous part,
lift it, and allow it to drop into the hole by its own weight, and by
this simple operation, a hole to the depth of five feet and upwards
is perforated with ease and expedition. When the boring is completed,
the fragments are carefully removed, and the hole is made as dry as
possible, which is done by filling it partially with stiff clay, and
then driving into it a tapering iron rod, called the _claying bar_,
which nearly fills it. This, being forced in with great violence,
drives the clay into all the crevices of the rock, and secures the
dryness of the hole. Should this plan fail, tin cartridges are used:
these are furnished with a stem or tube, as shown in the following
figure, through which the powder may be ignited. When the hole is dry,
the powder is introduced, mixed sometimes with quicklime, which, it
is said, increases the force of the explosion. A long iron or copper
rod, called the _pricker_, is then inserted amongst the powder, and
is afterwards withdrawn, when the priming powder is introduced. The
hole is filled up with burnt clay, pounded brick, stone, or any other
substance not likely to produce a spark during the ramming. This is
called the _tamping_. In filling up the hole, the chief danger is the
production of a spark among the materials, a circumstance which has
occasioned the most fatal and distressing accidents to quarriers.
Prickers and rammers of copper, or of bronze, have been employed, but
their greater expense, and liability to twist and break, have prevented
their general introduction.
[Illustration]
The quarrier is, of course, accustomed to suppose that the more firmly
he rams in the powder, the greater will be the resulting effect. It
is, however, a curious property of sand, that it fills up all the void
spaces in the tube or hole, and for some rocks entirely supersedes the
necessity of ramming and pricking.
When the hole is fully charged with the powder and wadding, the pricker
is withdrawn, and the small tubular space, or vent-hole, which it
leaves, is sometimes filled up with powder; but, for the sake of
economy, it is more common to insert straws filled with powder, and
joined together, so as to reach the required depth. The lower straw is
one terminating in the root part, where a natural obstruction occurs,
or it is artificially stopped with clay to prevent the powder from
being lost. The lower part of the priming straw is pared quite thin,
so as to insure the inflammation of the charge of powder in the hole.
Sometimes the fire is conveyed by means of the large and long green
rushes, which grow in marshy ground. A slit is made in one side of the
rush, along which the sharp end of a bit of stick is drawn, so as to
extract the pith, when the skin of the rush closes again by its own
elasticity. This tube is filled up with gunpowder; it is then dropped
into the vent-hole, and made steady with a bit of clay. This being
done, a slow match, called a _smift_, consisting generally of a bit of
soft paper, prepared by dipping it into a solution of saltpetre, is
carefully applied to the priming powder. When this match is about to be
fired, the quarriers usually blow a horn or ring a bell, to give notice
to all around them to retire. The explosion commonly takes place in
about a minute; the priming first explodes, attended only with flame; a
short interval of suspense commonly ensues; the eyes of the bystanders
being anxiously directed towards the spot; the rock is instantly seen
to open, when a sharp report or detonating noise takes place, and
numerous fragments of stone are observed to spring into the air, and
fly about in all directions, from amidst a cloud of smoke. The quarrier
then returns with alacrity to the scene of his operations.
[Illustration]
The accompanying figure shows the plan of blasting the rock, and a
section of the hole ready prepared for firing. The portion of the rock
to be dislodged by the explosion is that included between A and B. The
charge of powder is represented as filling the bore to C, from which
point to the top, the hole is filled up with _tamping_. The _smift_ is
represented at D.
In the year 1831, a patent was taken out by Mr. Bickford, of Tucking
Mill, Cornwall, for an invention called “the Miner’s Safety Fuse.”
It consists essentially of a minute cylinder of gunpowder, or other
suitable explosive mixture, inclosed within a hempen cord, which
is first twisted in a peculiar kind of machine, then overlaid to
strengthen it; afterwards it is varnished with a mixture of tar and
resin to preserve the powder from moisture, and finally is coated with
whitening to prevent the varnish from sticking to the fingers, or the
fuses to one another. These fuses are said to have been used with good
effect, and to have greatly diminished the number of accidents.
The application of Electricity to the Blasting of Rocks.
Perhaps the greatest modern improvement that has been made in blasting
rocks has been by the introduction of the galvanic battery. It is
well known that by closing the circuit of a voltaic current by means
of thin platinum wire, or by fine iron or steel wire, the platinum
becomes red-hot, and the iron or steel becomes instantly fused. All,
therefore, that is necessary is to connect the two terminal wires of
a voltaic battery by means of a fine wire of platinum or iron, and to
bury this in gunpowder contained in a tin canister, or a fuse connected
with a deposit of gunpowder. This was the method adopted by Colonel
Pasley in removing the Royal George, which lay sunk at the bottom of
the water at Spithead. Canisters of gunpowder, sometimes to the extent
of three thousand pounds’ weight, were employed, and securely deposited
in the sunken vessel, by workmen who descended in the diving-bell; the
terminal wires of the battery, connected as above stated, having been
previously inserted in the canisters, and these wires being extended
to a great distance, the explosion took place the instant they were
connected with the voltaic battery. After the vessel was thus blown
to pieces by repeated explosions, divers descended to clear away the
wreck, and to attach guns, &c., to chains let down from a ship above,
and which were then hauled up by means of a crane.
Mr. Morgan, in the _American Journal of Science_, describes a fuse or
cartridge which he has used with success in connexion with the voltaic
battery. This cartridge is prepared by joining two pieces of clean
copper wire to the ends of a fine steel wire, about one quarter of an
inch in length, by means of waxed silk; a thin piece of wood is then
spliced to both copper wires, to protect the steel wire from accidents,
and to enable the maker to introduce it easily into a quill or small
paper tube, which is to form the cartridge. This tube is filled with
fine gunpowder, and made air and water-tight. Another piece of wood is
then attached to this arrangement, and one of the copper wires is bent
over so as to form an angle with the straight wire.
When it is required to use this cartridge, the copper wires are rubbed
with sand-paper, and twisted round the wires of the voltaic battery.
The cartridge is then placed deep in the hole made to receive the
gunpowder, and the charge is fired from any distance.
Mr. Morgan found this arrangement very useful in removing stumps of
trees; but one of his applications of it was curious and novel: he
exploded some powder in a pond at the depth of ten feet, with the
battery at the distance of two hundred and ten feet; the explosion,
which was instantaneous, had the effect of killing a large eel; and “I
have no doubt,” says Mr. Morgan, “that wild-fowl will yet be killed by
means of shells placed at low-water on the banks where they feed; and
by means of long connecting wires, the shells can be made to explode
simultaneously among the birds.”
But the grandest application of gunpowder and the voltaic battery to
the blasting of rocks, was made in the month of January, 1843, at
Dover. It was determined by these means to attempt the removal of an
enormous mass of the cliff facing the sea, which formed an obstruction
to the line of railroad. A portion of the cliff which was penetrated
by the tunnel made through Shakspeare’s Cliff gave way, about two
years previously. About fifty yards of the tunnel were carried away,
and a clear space was thus formed for the line of railroad, with the
exception of a projecting point, which, prior to the slip alluded to,
was the extremity of the part of the cliff pierced by the tunnel, and
to remove which was the object of the operation in question.
To clear away this mass by the tedious process of manual labour, would
have cost above twelve thousand pounds; and this consideration, as
well as the time that would have been lost, induced Mr. Cubitt, the
engineer, to try the bold expedient of blowing it away with gunpowder.
“It cannot be denied,” remarks Captain Stuart, whose account of this
great engineering operation we follow, “that there was apparent danger
in the undertaking, for the weight of the mass to be removed was
estimated at two million tons, and the quantity of powder used was
more than eight tons, or eighteen thousand pounds. The quantity used in
blowing up the fortifications of Bhurtpore was twelve thousand pounds,
and this is said to have been the greatest explosion that had ever
previously taken place for any single specific object.”
The front of the projection was about one hundred yards wide; this
front was pierced with a tunnel about six feet in height, and three
in breadth; three shafts, equidistant from each other, and from the
entrances to the tunnel, were sunk to the depth of seventeen feet, and
galleries were run, one from each shaft, parallel with each other, and
at right angles with the line of the tunnel. These galleries varied
in length, the longest having been twenty-six feet, and the shortest
twelve feet, and at their extremities chambers were excavated in a
direction parallel with the tunnel. This description will be the better
understood by reference to the following figure. 1. The tunnel. 2. The
shafts. 3. The galleries. 4. The chambers.
[Illustration]
In the chambers, the powder was deposited in three nearly equal
quantities; it was done up in fifty-pound bags, and the proportion
in each chamber was contained in a wooden case, nearly as large as
the chamber itself. Ignition was communicated by means of a voltaic
battery; the conducting wires, one thousand feet in length, were
passed over the cliff, one to each chamber, and the electricity was
communicated in a shed built for the purpose on the top of the cliff,
about fifty yards from the edge. The explosion was conducted by
Lieutenant Hutchinson, R.E., who was engaged with General Pasley in
blowing up the wreck of the Royal George. The time appointed for the
explosion to take place, was two o’clock P.M., 26th January, 1843, the
tide being then at its lowest ebb. The arrangements, to preserve order
and prevent danger, were good. A space was kept clear by a cordon of
artillery, and the following programme was issued:--
“Signals, January 26, 1843.
“1st. Fifteen minutes before firing, all the signal flags will be
hoisted.
“2nd. Five minutes before firing, one gun will be fired, and all the
flags will be hauled down.
“3rd. One minute before firing, two guns will be fired, and all the
flags (except that on the point which is to be blasted) will be
hoisted up again.”
These signals were given exactly at the specified times, and when
the expected moment arrived, a deep subterranean sound was heard, a
violent commotion was seen at the base of the cliff, and the whole mass
slid majestically down, forming an immense _débris_ at the bottom.
Tremendous cheers followed the blast, and a royal salute was fired.
The remarks of different intelligent observers, as to the effects of
this explosion, would of course differ according to their position with
respect to the scene of explosion. One observer states that “the earth
trembled to the distance of half a mile; a stifled report, not loud,
but deep, was heard; the _base_ of the cliff, extending on either hand
to upwards of five hundred feet, was shot as from a cannon, from under
the superincumbent mass of chalk seaward; and in a few seconds not less
than a million tons of chalk were dislodged by the shock, and settled
gently down into the sea below.”
But the most eminent observer who has described the effects of this
explosion is Sir John Herschel, from whose letter to the _Athenæum_ we
gather the following particulars. His position was on the summit of the
cliff, next adjoining the scene of operations, to the southward, the
nearest point to which access was permitted.
Sir John Herschel was particularly struck with “the singular and almost
total absence of all those tumultuous and noisy manifestations of
power, which might naturally be expected to accompany the explosion
of so enormous a quantity (19,000lbs.) of gunpowder.” He describes
the noise which accompanied the immediate explosion as “a low murmur,
lasting hardly more than half a second, and so faint, that had a
companion at my elbow been speaking in an ordinary tone of voice, I
doubt not it would have passed unheeded.”
The fall of the cliff, the ruins of which extended over no less
than eighteen acres of the beach, to an average depth of fourteen
feet, was not accompanied with any considerable noise. “The entire
absence of smoke was another and not less remarkable feature of the
phenomenon. Much dust, indeed, curled out at the borders of the vast
rolling and undulating mass, which spread itself like a semi-fluid
body, thinning out in its progress; but this subsided instantly; and
of true smoke there was absolutely not a vestige. Every part of the
surface was immediately and clearly seen--the prostrate flagstaff
(speedily re-erected in the place of its fall)--the broken turf,
which a few seconds before had been quietly growing at the summit of
the cliff--and every other detail of that extensive field of ruin,
were seen immediately in all their distinctness. Full in the midst of
what appeared the highest part of the expanding mass, while yet in
rapid motion, my attention was attracted by a tumultuous and somewhat
upward-swelling motion of the earth, whence I fully expected to see
burst forth a volume of pitchy smoke, and from which my present
impression is, that gas, purified from carbonaceous matter in passing
through innumerable fissures of cold and damp material, was still in
progress of escape; but whether so or not, the remark made at the
moment is sufficient to prove the absence of any impediment to distinct
vision.”
The amount of tremor experienced by Sir John Herschel at the point
where he was standing was so slight, that he thinks he has felt
it surpassed by a heavy waggon passing along a paved street. “The
impression, slight as it was, was single and brief, and must have
originated with the first shock of the powder, and not from the
subsequent and prolonged rush of the ruins.” We have already noticed
the remark of one observer, that “the earth trembled to the distance of
half a mile;” but this seems to be a mistake; the writer fancied that
it must have been so, and that he should be suspected if he were to
state it otherwise. It is to be regretted that people do not endeavour
to describe what they see and hear, without the embellishment of the
imagination.
This grand experiment was no less grand from the absence of noise,
smoke, earthquake, and fragments hurled to vast distances through
the air. “I have not heard of a single scattered fragment flying out
as a projectile in any direction”--continues Sir John Herschel--“and
altogether the whole phenomenon was totally unlike anything which,
according to ordinary ideas, could have been supposed to arise from the
action of gunpowder. Strange as it may seem, this contrast between the
actual and the expected effects, gave to the whole scene a character
rather of sublime composure than of headlong violence--of graceful ease
than of struggling effort. How quietly, in short, the gigantic power
employed performed its work, may be gathered from the fact, that the
operators themselves who discharged the batteries were not aware that
they had taken effect, but thought the whole affair a failure, until
reassured by the shout which hailed its success.”
Sawing the Stones for the Mason.
Whatever may be the purpose to which the stone is to be applied, the
larger blocks obtained from the quarry must be cut into smaller and
more manageable pieces; this is done by _sawing_. The saw used is a
long blade of steel without teeth, fixed in a heavy wooden frame,
similar in principle to that which holds the finer spring-saws employed
by cabinet-makers. The stone-saw, from its great size, however,
requires a more powerful contrivance for drawing it to the proper
degree of tension: this consists of a long screw-bolt fixed to a piece
of chain, which hooks over one of the upright arms of the frame; a
similar chain from the other carries a swivel-joint with a screw-nut
to receive the screw: by turning the swivel by a lever, the nut on the
screw draws up or tightens the chains, and that draws the blade tight,
which is contained between the other ends of the arms.
These huge saws are worked by one or two men, who, in London
stone-yards, sit in watch-boxes, in order to be sheltered from the sun
and rain. Barrels filled with water, which is allowed to drop out at a
tap, are mounted on the block of stone, so that the water may drip into
the cut and facilitate the motion of the saw by removing some of the
friction, as well as prevent it becoming hot, and so losing its temper
by the same cause.
In some large establishments, the sawing is effected by machinery. The
block is fixed in a proper position, and a group of saws brought to act
on it. These saws are all arranged parallel, according to the thickness
of the pieces into which the stone is to be cut; and a steam-engine
being brought to bear on the whole group, the cutting is effected with
great rapidity.
The Processes of Stone-Masonry.
When the stone is sawed to the proper size, the surfaces which are
exposed to view, have to be made smooth and even. The tools used by the
mason for this purpose consist of iron chisels of different widths, and
principally of a sharp-pointed one called a _pointer_; these chisels
are struck with a mallet made of a conical-formed lump of hard wood,
fixed to a short handle.
[Illustration: Stone-Sawyer.]
The _pointer_ is used for chipping off the principal roughnesses on the
face and edges, and for working the whole face over to bring it level,
the workman trying his work by applying a _straight-edge_ occasionally
to it. When the front and edges are made _true_, the face is sometimes
_tooled_ over, so as to leave regular furrows in it, according to
certain forms, by which the different kinds of work are distinguished.
But this practice is going out of use, now that soft free-stone is
so much employed in building. In old edifices, such as St. Paul’s,
Whitehall, &c., &c., the stone will be found to be wrought on its face
in the manner alluded to.
Stones in buildings are not only fixed with mortar, as bricks are, but
are further secured in their places by being clamped together with iron
clamps. These are short iron bars, from seven to twelve inches long,
one and a half wide, and half an inch thick, according to the size of
the stone; the ends of the clamps being turned down a little, to afford
a better hold. A channel is cut in the two contiguous stones deep
enough for the clamp to lie in, and the ends of the channel are sunk
deeper, to receive the turned-down ends of the clamp; when this is put
into the channel, molten lead is poured in to fill up the interstices,
to keep the clamp in its place, and to prevent it from rusting.
From the expense of carrying and working stone, the walls of buildings
at a distance from a quarry, such for example as those in London, are
seldom now built of solid stone, but a facing of this material is
applied only on the external surface of the wall, which is built of
brick. This kind of work is called _ashler_ work, and both the brick
and stone-work must be executed with considerable care, to enable
a wall composed of two materials to preserve its perpendicularity;
it being obvious, that if the brick part yielded to the weight, it
must, from its construction, do so more than the stone facing, and,
therefore, the wall would bend inwards and become crippled.
The width of the courses of ashlers must, therefore, be made equal
exactly to a certain number of courses of bricks with the intervening
mortar, and the brick-work must be executed with such care, that this
number of courses may be everywhere of the same width in the whole
height of the wall. In every course of ashler there must be solid
stones laid quite, or nearly quite, across the width of the wall to
form a _bond_ to the stone facing, and all the stones of the ashler
must be fixed with iron cramps to one another and to these bond-stones.
But, however carefully a faced wall may be executed, it is never so
firm or durable as one built entirely of either material; indeed,
if well executed, of good materials, and of competent thickness in
proportion to its height, a brick wall is the most durable, light, and
efficient structure that can be erected.
When stone is to be cut into cornices, mouldings, &c., the blocks
having been sawed, the ends, top and bottom, are worked very true and
parallel, or perpendicular to each other, and one edge or _arris_ cut
to a perfectly straight line; a thin wooden mould of the section of the
cornice is then applied to each end, and the profile of the mouldings
marked out on the stone. The workman being guided by this figure, cuts
away the stone down to the general surface of the mouldings, and then
proceeds to get the flat fillets of the mouldings perfectly straight
and true by the rule; these again guide him in working the curved
mouldings, such as _ovolos_, _cavettos_, _cyma rectas_, and _ogees_;
when these are cut nearly to their profile, and perfectly straight on
the _bed_ line, they are finished off by being rubbed down smooth by
thin long straight-edges of stone.
Foliage and carved work is executed by a better kind of workman,
possessing some of the taste of an artist, and he works on the same
general principles as a sculptor when executing a statue; it would be
foreign to our present object, therefore, to dwell on this branch of
the mason’s art.
It often, or even most commonly occurs, that the distance between
two columns of a portico, is of greater length than a stone can be
obtained, and if the architrave, or that part of the _entablature_
immediately over the capitals of the columns, be looked at attentively,
a stone will be perceived between the columns apparently unsupported,
for neither end rests on the column, and the joints of those ends are
upright, not presenting any character of a voussoir-stone or arch. The
contrivance by which such an architrave stone is supported deserves to
be described.
[Illustration]
The stone in question has a projecting part, wrought at each end, of
the form shown in the annexed figure; this projection is received into
a corresponding cavity, cut in the end of the stone supported by the
column, and the joint is thus really an arched or wedge-shaped one,
though the bevel line is concealed, and the two stones, when put
together, present only a vertical joint.
The mason uses _squares_, _levels_, _plumb-lines_, and _straight-edges_
to set out his work, and trowels and mortar to set the stones with;
but the latter is rather used to make the joints water-tight than
to keep the stones together, this being effected by their weight or
by iron clamping. Formerly the mason required far more accurate and
extensive knowledge of geometry than is possessed by persons of the
trade at present; this was when he was called on to construct groined
and vaulted roofs, enriched with carved work and pendent corbels,
where the nicest workmanship was required, to ensure the stability of
the light and graceful columns and vaulting of a Gothic cathedral. It
was this possession of superior skill and knowledge that caused the
establishment of the Society of Freemasons, which dates its rise from
the tenth or eleventh century.
Marble, from its costliness, and the difficulty of working it, is
seldom, if ever, used in solid pieces in buildings; thin facings of
it are set upon stone _backings_, much as rare woods are used in
_veneering_ by the cabinet-maker. The marble is sawn into thin slabs,
like other stone, and the face is polished by rubbing on it the surface
of another piece, fine sand, mixed up with water, being used to cause
abrasion.
Various contrivances are resorted to for cutting marble, and
building-stones generally, into _curved_ forms. In some cases a lever
is made to work at one end on a pivot, while at the other end is
attached a curved piece of sheet-iron, which passing backwards and
forwards over the stone, cuts it in a circular form. In other cases
a cylinder of sheet-iron is formed; and this being allowed to fall
vertically on the surface of the stone, and rotated rapidly, cuts out
a piece of stone of the diameter of the cylinder. Sometimes, when a
large circular piece of stone is required, a kind of wheel is employed,
furnished on its under surface with four curved cutting-irons,
and these cutters, when the wheel revolves, cut the stone. By a
modification of the arrangements, an oval instead of a circular curve
may be given to the piece of stone.