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On The Duration Of Machinery
340. The time during which a machine will continue to perform...

Of Copying By Stamping
128. This mode of copying is extensively employed in the art...

Increase And Diminution Of Velocity
32. The fatigue produced on the muscles of the human frame d...

On The Future Prospects Of Manufactures As Connected With Science
453. In reviewing the various processes offered as illustrat...

Distinction Between Making And Manufacturing
163. The economical principles which regulate the application...

On The Position Of Large Factories
277. It is found in every country, that the situation of lar...

Copying With Elongation
140. In this species of copying there exists but little rese...

On Over Manufacturing
284. One of the natural and almost inevitable consequences of...

Of Copying With Altered Dimensions
147. Of the pentagraph. This mode of copying is chiefly used ...

Printing From Surface
91. This second department of printing is of more frequent a...

Of Printing From Cavities
83. The art of printing, in all its numerous departments, is ...

Exerting Forces Too Great For Human Power And Executing Operations Too Delicate For Human Touch
56. It requires some skill and a considerable apparatus to e...

On Combinations Amongst Masters Or Workmen Against Each Other
353. There exist amongst the workmen of almost all classes, ...

Sources Of The Advantages Arising From Machinery And Manufactures
1. There exists, perhaps, no single circumstance which disti...

Of Copying
82. The two last-mentioned sources of excellence in the work ...

Of Copying By Casting
105. The art of casting, by pouring substances in a fluid st...

On The Method Of Observing Manufacturies
160. Having now reviewed the mechanical principles which reg...

On The Division Of Labour
241. We have already mentioned what may, perhaps, appear par...

On The Effect Of Machinery In Reducing The Demand For Labour
404. One of the objections most frequently urged against mac...

On The Influence Of Durability On Price
197. Having now considered the circumstances that modify what...

Of Copying By Casting

105. The art of casting, by pouring substances in a fluid
state into a mould which retains them until they become solid, is
essentially an art of copying; the form of the thing produced
depending entirely upon that of the pattern from which it was

106. Of casting iron and other metals.--Patterns of wood or
metal made from drawings are the originals from which the moulds
for casting are made: so that, in fact, the casting itself is a
copy of the mould; and the mould is a copy of the pattern. In
castings of iron and metals for the coarser purposes, and, if
they are afterwards to be worked even for the finer machines,
the exact resemblance amongst the things produced, which takes
place in many of the arts to which we have alluded, is not
effected in the first instance, nor is this necessary. As the
metals shrink in cooling, the pattern is made larger than the
intended copy; and in extricating it from the sand in which it is
moulded, some little difference will occur in the size of the
cavity which it leaves. In smaller works where accuracy is more
requisite, and where few or no after operations are to be
performed, a mould of metal is employed which has been formed
with considerable care. Thus, in casting bullets, which ought to
be perfectly spherical and smooth, an iron instrument is used, in
which a cavity has been cut and carefully ground; and, in order
to obviate the contraction in cooling, a jet is left which may
supply the deficiency of metal arising from that cause, and which
is afterwards cut off. The leaden toys for children are cast in
brass moulds which open, and in which have been graved or
chiselled the figures intended to be produced.

107. A very beautiful mode of representing small branches of
the most delicate vegetable productions in bronze has been
employed by Mr Chantrey. A small strip of a fir-tree, a branch of
holly, a curled leaf of broccoli, or any other vegetable
production, is suspended by one end in a small cylinder of paper
which is placed for support within a similarly formed tin case.
The finest river silt, carefully separated from all the coarser
particles, and mixed with water, so as to have the consistency of
cream, is poured into the paper cylinder by small portions at a
time, carefully shaking the plant a little after each addition,
in order that its leaves may be covered, and that no bubbles of
air may be left. The plant and its mould are now allowed to dry,
and the yielding nature of the paper allows the loamy coating to
shrink from the outside. When this is dry it is surrounded by a
coarser substance; and, finally, we have the twig with all its
leaves embedded in a perfect mould. This mould is carefully
dried, and then gradually heated to a red heat. At the ends of
some of the leaves or shoots, wires have been left to afford
airholes by their removal, and in this state of strong ignition a
stream of air is directed into the hole formed by the end of the
branch. The consequence is, that the wood and leaves which had
been turned into charcoal by the fire, are now converted into
carbonic acid by the current of air; and, after some time, the
whole of the solid matter of which the plant consisted is
completely removed, leaving a hollow mould, bearing on its
interior all the minutest traces of its late vegetable occupant.
When this process is completed, the mould being still kept at
nearly a red heat, receives the fluid metal, which, by its
weight, either drives the very small quantity of air, which at
that high temperature remains behind, out very through the
airholes, or compresses it into the pores of very porous
substance of which the mould is formed.

108. When the form of the object intended to be cast is such
that the pattern cannot be extricated from its mould of sand or
plaster, it becomes necessary to make the pattern with wax, or
some other easily fusible substance. The sand or plaster is
moulded round this pattern, and, by the application of heat, the
wax is extricated through an opening left purposely for its

109. It is often desirable to ascertain the form of the
internal cavities, inhabited by molluscous animals, such as those
of spiral shells, and of the various corals. This may be
accomplished by filling them with fusible metal, and dissolving
the substance of the shell by muriatic acid; thus a metallic
solid will remain which exactly filled all the cavities. If such
forms are required in silver, or any other difficulty fusible
metal, the shells may be filled with wax or resin, then dissolved
away; and the remaining waxen form may serve as the pattern from
which a plaster mould may be made for casting the metal. Some
nicety will be required in these operations; and perhaps the
minuter cavities can only be filled under an exhausted receiver.

110. Casting in plaster. This is a mode of copying applied to
a variety of purposes: to produce accurate representations of the
human form--of statues--or of rare fossils--to which latter
purpose it has lately been applied with great advantage. In all
casting, the first process is to make the mould; and plaster is
the substance which is almost always employed for the purpose.
The property which it possesses of remaining for a short time in
a state of fluidity, renders it admirably adapted to this object,
and adhesion, even to an original of plaster, is effectually
prevented by oiling the surface on which it is poured. The mould
formed round the subject which is copied, removed in separate
pieces and then reunited, is that in which the copy is cast. This
process gives additional utility and value to the finest works of
art. The students of the Academy at Venice are thus enabled to
admire the sculptured figures of Egina, preserved in the gallery
at Munich; as well as the marbles of the Parthenon, the pride of
our own Museum. Casts in plaster of the Elgin marbles adorn many
of the academies of the Continent; and the liberal employment of
such presents affords us an inexpensive and permanent source of

111. Casting in wax. This mode of copying, aided by proper
colouring, offers the most successful imitations of many objects
of natural history, and gives an air of reality to them which
might deceive even the most instructed. Numerous figures of
remarkable persons, having the face and hands formed in wax, have
been exhibited at various times; and the resemblances have, in
some instances been most striking. But whoever would see the art
of copying in wax carried to the highest perfection, should
examine the beautiful collection of fruit at the house of the
Horticultural Society; the model of the magnificent flower of the
new genus Rafflesia--the waxen models of the internal parts of
the human body which adorn the anatomical gallery of the Jardin
des Plantes at Paris, and the Museum at Florence--or the
collection of morbid anatomy at the University of Bologna. The
art of imitation by wax does not usually afford the multitude of
copies which flow from many similar operations. This number is
checked by the subsequent stages of the process, which, ceasing
to have the character of copying by a tool or pattern, become
consequently more expensive. In each individual production, form
alone is given by casting; the colouring must be the work of the
pencil, guided by the skill of the artist.

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