Page:An Elementary History of Art.djvu/194

 1 64 Sculpture. may be seen in the old gateways of Hampton Court. At the present day it is very frequently employed in the ornamentation of important buildings. Plaster of Paris, gypsum, when burned and reduced to powder, forms a paste which immediately sets, or becomes firm, on being mixed with its own bulk of water ; for this reason it is much used in making casts and architectural decorations. Alabaster, a kind of gypsum found in Tuscany and also in Derbyshire, was at one time much used for vases and statuettes. Limestone and Sandstone, softer and less durable ma- terials than marble, are largely employed for architectural ornaments. Wood. — The principal woods employed for carving are, that of the lime, which though soft is tough and durable, the oak, and the cedar. Ivory. — The carving of ivory was practised by the Romans. It was carried to great perfection in the early days of the Christian Church, when it was used for statuettes, tablets, and other ornaments, many of which may be seen in the South Kensington Museum. The ivory chair of St. Maximian, made in the sixth century, is still preserved in the Cathedral at Ravenna. In the year 803 two beautifully -carved ivory chairs were presented to Charlemagne. Gems. — The principal gems used by ancient engravers were : carnelians, chalcedony, onyx, sardonyx, agates, jaspers, garnets, beryls, amethysts, sapphires, rubies, topazes, tur- quoises, etc. For cameos, the onyx was preferred above any other stone.