The Opus Alexandrinum and Sculptured Stone Roudels in the Retro-Choir of Canterbury Cathedral

AND SCULPTURED STONE ROUNDELS. 191 works of art and, according to the Chronicle of Leone, Bishop of Ostia, founded, in 1066, a school of mosaic work under the direction of Greek masters, and so revived an art " which had been for more than 500 years extinct in Italy." These mosaics of Monte Cassino have disappeared, but we know from Leone of Ostia that those of the pavement of the Church were made of marble of different colours (cf. Gersprach : La Mosaique, p. 152). The art of mosaic, thus revived, flourished during the twehth and thirteenth centuries, gradually losing its Byzantine influence and taking on a Western European, or Gothic character.1 These mediaeval mosaics may be divided into four classes :— (1) Mosaics used for decorating waUs and vaults. (2) Mosaics used • for decorating columns, pulpits, altars, etc. (3) Pavement mosaics made partly of large pieces of marble, and partly of smah tesserae, the former being used for the ground work and the latter for the main hnes. (4) Wood mosaics. (These were largely used in Mahometan buildings between the fourteenth and seventeenth centuries.) Mosaics in which glass, or enamel, was principally employed were known in the thirteenth century as " Cosmati " work from the name (Cosmas) of the family of artists who were its chief exponents. There is work of this kind in Westminster Abbey in the Shrine of Edward the Confessor (1269) which was wrought by " Petrus civis Romanus," who was probably a pupil of the Cosmati. The tomb of Henry III is also a fine specimen of this land of work.2 Another Roman artist, named Odericus, decorated the space in front of the high altar with mosaic in the latter hah of the thirteenth century. 1 J. RomiHy Allen, Barly Christian Symbolism. 2 There is a pavement of this kind in the Baths of Caracalla, Rome. Vide the article by Mr. Nesbitt already cited.