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Babbage, Charles, 1792-1871

"On the Economy of Machinery and Manufactures"

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.


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