MOSAIC, an imitation or reproduction of a painting or ornamental design, formed gener ally by means of pieces of opaque glass of dif ferent colors; also by colored stones (espe cially marbles and precious stones) placed side by side, and attached by being bedded in a ce ment. The art originated in the East, but re ceived its perfection from the Greeks, and was thus conveyed to the Romans. In Italy many floors ornamented with mosaic work have been found among ancient ruins. Afterward, when the art was revived in Italy, the Venetian school becoming very celebrated, Clement VIII, in the 17th century, had the interior of the dome of Saint Peter's decorated with this kind of work. The art was largely employed for copying painting by famous artists, and thus rendering permanent their original freshness and beauty. The Roman school of mosaicists is still the most famous, though excellent works have been produced in recent times by Vene tian and also by Russian artists. There is a studio for the production of mosaics in the Vatican at Rome. The most important works ex ecuted here in recent times are a series of por traits of the popes. In the most costly mosaics precious stones have been cut to furnish mate rials; but in common works of this art enamels of different colors, manufactured for the pur pose, are the material employed. Roman enam els are made of small rods of opaque colored glass. In the first place cakes of glass are made of every variety of color and shade likely to be required. As many as 10,000 shades are said to be in use. These cakes are drawn out into rods thicker or thinner, according as they are to be used for finer for coarser work, a great number being mere threads. They are kept in bundles, and arranged in sets corre sponding to their colors. For a work of mod
erate size a piece of dark slate or marble is prepared by being hollowed out like a box and filled with plaster of Paris; upon this plaster the artist draws the design or pattern, and the workman proceeds with his work by removing small squares of the plaster, and filling in these with pieces cut from the glass rods, the pieces being fixed in their places by a cement. Gradually, in this manner, all the plaster is re moved, and a picture is formed by the ends of the pieces of colored glass. It will easily be understood that this is a very slow process, and there are large pictures that have taken as many as from 12 to 20 years to produce. When mosaic pictures are to he viewed near at hand they are polished perfectly smooth with a flat stone and emery, and present a glossy surface similar to that of paintings in oil. When they are to he viewed at a distance the surface is left rough, when they present an appearance similar to pictures in fresco. Inlaid works, of agate and other costly stones, are executed on the same principle as mosaic, except that the stones are larger, and cut to the shape of dif ferent parts of the object to be represented. Works of this class are known as Florentine mosaics. Flowers and ornamental designs are the chief objects of this branch of the art. A mode has been invented of sawing the plate with the mosaic pictures into two or three sheets, and thus increasing the number of works produced at one time. Consult Barwell and Druitt, (Mosaics and Stained Glass) (New York 1909); Furnival, W. J.,