"The artist, having invented or conceived his subject, usually begins by making a small sketch of it in some soft and obedient substance, as clay or wax. He can change or alter this at his pleasure till he is satisfied with the lines and masses of the composition, and the proportions it will command of light and shadow. He then proceeds to copy this small but useful sketch, as his guide, in its general arrangement, for his full-sized model. Before commencing the larger model it is necessary to form a sort of skeleton or framework of iron and wood, with joints made of wire, to support the great mass of clay in which the figure or group is now to be executed. This iron frame is firmly fixed upon a turning bench, or banker, so that the model may be constantly moved without difficulty, so as to be seen in different lights and in various points of view. As the clay is likely to shrink as it gets dry, it is necessary occasionally to wet it. This is done by sprinkling water over it with a brush, or from a large syringe, and by laying damp cloths upon it. This is the ordinary process for making a model in the 'round.' "In modelling in _rilievo_ of either kind, _alto_ or _basso_, a plane or ground is prepared upon which the design is, or should be, carefully drawn. This may be made of clay floated or laid upon a board, or the ground may be of slate, or even of wood, though the latter is objectionable, in large works especially, from its liability to shrink and to be warped by the action of damp or moisture. The clay is then laid in small quantities upon this ground, the outline being bounded by the drawing, which should be carefully preserved; and the bulk or projection of the figures is regulated by the degree of relief the sculptor desires to give to his design. "If the final work is to be baked in clay (_terra-cotta_) there must be no iron or wooden nucleus, as it would interfere with the model drying regularly and uniformly, and probably cause it to crack in shrinking. The model is therefore prepared for drying without such support. When perfectly free from moisture the model is placed in an oven and baked slowly, by which it acquires great hardness and the peculiar brownish-red color seen in these works. This art has been brought to great perfection in England in modern days.