BYZANTIUM. Constantine, on transplanting his capital to Byzantium (A.D. 330), selected the best artisans in glass, and not only gave them studios in a quarter of the city called 'glass-making,' but caused them to be exempt from the tax levied by previous emperors. Accordingly glass-makers flocked from fallen Rome, carrying the fame and skill of the Imperial city to the East, and Byzantium supplied all Europe with verre de luxe until the rise of Venice. Factories were re established in Greece, Macedonia, Phoenicia, and Alexandria, and after the Arab conquest they continued to be the sole sotrees of artistic glass through the Middle Ages. The early Byzantines followed classic models, often badly, but later a Byzantine school arose which prevailed through out Europe until the thirteenth century. Mosaic art, under the impetus of Christianity, was de veloped to its greatest glory for mural decora tion, as the Byzantines believed and demon strated that "mosaic is the only painting for eternity." Their world-renowned specimens at Ravenna (A.D. 440) are superior to those of the Romans. In the Saint Sophia are mo saics made in the sixth century. On the lower walls these mosaics are of marble, and of glass cubes or tesserfe on the upper walls and ceiling. These and its colored windows caused Justinian, its builder, to say, "I have surpassed thee, 0 Solomon." The Church of the Transfiguration, Mount Sinai, is adorned with precious Byzantine mosaics of the seventh and eighth centuries. The Byzantine churches were usually lighted by a series of small windows around the base of the dome. Some of the original plates of cast glass still remain at Saint Sophia. Colored window glass is not mentioned till toward the end of the eighth century. A common method of inserting it, which is still practiced in the East, was to perforate slabs of marble, or even the plaster, in patterned openings and place the glass in these.
One of the terms of peace at the beginning of the eighth century between Caliph \Valid and Justinian II. was that the latter should furnish a quantity of mosaic for his mosque at Damascus. A series of Byzantine mosaics extends from Con stantine to Charlemagne. So late as the eleventh century, Pope Victor III. sent to Constantinople for workers in mosaic. Imitation stones were also made wonderfully well there. The blue cup at Monza (A.D. 600), three inches in diameter, said to be made of a single sapphire; the celebrated emerald table captured at Toledo in the four teenth century, long believed to be cut from a single emerald, inlaid with gold and precious stones, and valued at 100,000 dinars; and the famous Sacro Catino of Genoa, a shallow dish which passed as one of the most sacred relics of Christendom, the veritable `Sangraal,' the ransom of a captive king, and supposed to be cut from an emerald until pronounced green glass, in 1761, by a French chemist—were all from Byzantine fac tories. The precious sacrament cups of glass, used in the Church service, were theirs. They made the glass medallions circulated as test weights for money throughout the large estates of the Fatimite princes, which have been mis taken for coins. These were abolished in 888, but Venice continued to make glass weights in 1279, as the old Greeks had done. From Byzantine centres the Crusaders brought back into Europe the manufacture of glass, and it is probably from this source that Venice received its early impulse and first lessons in glass-mak ing.