e original model. Some skill is required in making
moulds, in order to provide for projecting parts and under-cuttings;
practice alone can teach the artist how to deal with those difficulties
when they occur. The above general instructions sufficiently explain the
ordinary processes of moulding and casting in plaster.

"In metal-casting or founding great attention must be paid to the
strengthening of the parts to bear the weight of the metal; but the
principle described in plaster-moulding applies also to the preparation
for metal-casting. The mixture of metals to form bronze, the proper
heating of the furnace, burning and uniting parts, chasing and other
processes of founding cannot be fully described in this place. They
belong to a distinct practice, and to be well understood must be studied
in the foundry.

"If the model--now reproduced in plaster--is to be copied in marble or
stone, the first step is to procure a block of the required size. Two
stones, called _scale-stones_, are then prepared, upon one of which the
model or plaster cast is placed, and upon the other the rough block of
marble. The fronts of these stones have figured marks or 'scales,' to
use the technical term, exactly corresponding. An instrument capable of
being easily moved, and which is fitted up with socket-joints and
movable arms, is then applied to the scale-stone of the model, and a
projecting point or 'needle' is made to touch a particular part of the
model itself. This is carefully removed to the scale-stone of the rough
block, and the marble is cut away till the 'needle' reaches so far into
the block as to correspond with the 'point' taken on the model. A
pencil-mark is then made to show that the _point_ is found and
registered. This process is repeated all over the model and block,
alternately, till a rough copy or shape of the model is entirely made.
These 'pointing' machines are not always precisely alike in their forms,
but the principle upon which they act is exactly similar in all. The
statue being thus rudely shaped out, the block is placed in the hands of
a superior workman, called a 'carver,' who, having the plastic model
near at hand to refer to, copies the more minute portions of the work by
means of chisels, rasps, and files, the pencil-marks made by the
'pointer' showing him the precise situation of the parts and the limit
beyond which he is not to penetrate into the marble. When the carver has
carried the work as far as the