The next procesa is " casting." The model being completed, a mixture is made of plaster of Paris and water, which is thrown over the whole. When this is " set," or hardened, the clay within it is picked out, and there remains an exact mould of the model. This is washed, and the interior is brushed over with any greasy substance, usually a composition of oil and soap, to prevent the fresh plaster, with which it is next to be filled, from adhering too firmly to it. After the mould is thoroughly filled in all its parts with this piaster, mixed to about the consistency of cream, the latter is left to set. The mould is then " knocked off" with chisels, and a " cast" of the model is pro. diced entire. If it is intended to execute the work In bronze, the tome gem ral Is ober-reed in the moulding ; but there are particular praceesee to be attended to, in order to enable the mould to bear the *eight of the metal, and to ensure the soundness of the " cant" [11noszra] In copying a model in marble, the first step is to prepare two stones of the same size, or at least with an exactly corresponding graduated scale marked on the front of each, on which the block of marble and the model are respectively to be placed. The fronts of the two scales are so constructed or fitted up, that a " pointing" instrument can be applied to them. This instrument is usually composed of a pole or standard, to which a long brass or steel " needle "—capable of being extended and withdrawn, loosened or fixed, and moved in every direc tion by means of ball-and-socket joints—is attached. This is made to touch a particular part of the model. The whole instrument is then removed to the scale-atone on which the rough block is placed, and tho marble is cut away till the needle reaches as far into the block as it had been fixed at upon the model. A pencil mark is then made upon
the two corresponding parts of the model and block, and thus what is technically called "a point" is taken. This process is repeated till the numerous points at fixed depths, corresponding throughout with the aurface of the model, are attained, and a rough copy of the sculptor's original work is thus mechanically made. These instruments for pointing marble statues are not always constructed in precisely the same manner. The practice of different sculptors has suggested various changes in detail, by which either the movement of the whole machine from one scale-atone to the other is facilitated, or a greater rapidity and security in taking points is attained; but the principle on which they act seems to be exactly similar in all. The statue being rudely blocked out or pointed, the marble is in this state put into the hands of a superior workman called a carver, who copies the minuter portions of the work, by means of chisels of various sizes, rasps, and files; the pencil marks or points showing him the limits beyond which he is not to penetrate into the marble. When the carver has carried the work as far as the sculptor desires, he proceeds himself to give it the finishing stroke, by retouching and improving the details of form and expression, by producing varieties of texture and surface, and by giving that general quality or appearance to the whole which consti tutes what is termed harmony of effect.