SCULPTURE, in its strict sense, is the art of carving or cutting any material into a pro posed form or shape. In its more general acceptation it is the art of representing objects by form; and is thus applied to carving, mo delling (or the plastic art), casting, whether in metal or other materials, and to gem-en graving. Sculpture is practised in various ways ; namely, in forming entire or insulated figures, as statues or groups, called, in tech nical language, the round ;' or in represent ing objects more or less raised without their being entirely detached from a background. This latter is termed ' relief,' and the degrees of relief are defined by modern writers and artists by the expression alto-rilievo, when the object is so salient as to be nearly round; basso-Alley°, when it is slightly raised from the background ; and mezzo-rilievo, when a medium is preserved between the extremely high and the very flat relief. There is another variety of this manner of working basso -rillevo, Which is only or chiefly found in Egyptian sculpture ; the outline is sunk into the piano or ground, and the parts are then formed and rounded on the principle of basso-rilievb. By this mode of working there is usually no pro jection beyond the profile or face of the ori ginal ground ; to gain effect therefore in this kine of relieved intaglio, the Egyptian artists frequently painted the sculpture.
The materials for modelling used by the ancients, were clay, wax, and plaster. The clay model was usually baked, by which it acquired a hardness scarcely inferior to stone. These terra cotta works were generally painted. The materials used for carved works comprised every substance', hard or soft, that could by any poSsibility be employed for the purpose. The Egyptians, whose great objects were to render their works durable, chiefly employed porphyry, basalt, and granite. For gold, silver, copper, lead (and their compounds) wax, and plaster, were all used. [BaoxzE ; FOUNDING.) Polylithic Sculpture was the name given to the combination of different marbles in the same work. When painting or colour ing was resorted to it was called Polythromic Sculpture.
The consideration of the various schools and far-famed 'works' of sculpture, as produc tions of genius and high art, lies beyond the range of the presentvolume; but the mechan ical operations of sculpture come fittingly under notice here.
The technical or mechanical processes of Sculpture are for the most part extremely simple. The sculptor usually begins by mak ing a slight sketch of his subject, either draw ing it on paper or at once modelling it on a small scale, in clay or wax. • He next proceeds to build up his statue of the desired size. Tho first thing necessary is 'to construct a sort of nucleus, or skeleton, by which' the clay may be supported. This is made of wood or iron,
according to the strength required, and the limbs are usually made moveable by attaching the skeleton parts to the main support, or trunk, by wire joints.' The figure is then built up in clay; ; and whether it is ultimately to be draped or not, it should always be mo delled naked, in order that the true forms may be easily distinguished, and the drapery made to fall naturally.. In modelling in relief, a plane, or ground as it is called, is prepared, upon which the sculptor carefully draws his design. The _clay is then laid and pressed upon this, the outline of the figures being bounded by the lines of the drawing. When the work is completed it is east in plaster of paris, by Means of a mould taken in that 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 gradu ated 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 com posed 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 direction by means of ball and socket joints, is attached. This is made to touch a particular part of the model. The whole in strument is then removed to the scale stone on which the rough block is placed, and the 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, corre sponding throughout with the surface of the model, are attained, and a rough copy of the sculptor's original work is thus mechanically made. The practice of different sculptors has suggested various changes in detail ; but the principle 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 strokes, by retouching and im proving 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 constitutes what is termed harmony of effect.