was erected at Murano; but the art of painting glass could not be unknown at this last place, where it originated. It is true, that in process of time the Florentine and Venetian glass appeared to be not sufficiently transparent for such purposes; and that a preference was given to that of France and of England, the clearness and transparency of which was better adapted for receiving the colours, without too much obscuring the light. It had this other advantage, that the colours were burnt in the glass, in the manner described by Vasari, instead of being laid on with gums or other vehicles; hence they had greater brilliancy, and were more capable of resisting the injuries of time. This was a Flemish, or rather a French invention, and the Italians unquestionably received it from France. Bramante invited from that country the two artists above mentioned, who, besides the windows of the Vatican palace, that were wrought with colours burnt into the glass, and destroyed in the sack of Rome, in the time of Clement VII. ornamented two in the church of S. Maria del Popolo, with those scriptural histories that yet remain perfectly brilliant in colour, after the lapse of three centuries. Soon after this Claude died at Rome. William survived him many years, and from that time continued to reside in Arezzo. He there was engaged in the service of the capital, where one of his painted glass windows is preserved in the Capponi chapel, at the church of S. Felicità; and he taught the art to Pastorino of Siena, who exercised it very skilfully in the state saloon of the Vatican, after the designs of Vaga, and in the cathedral of Siena. This artist is reckoned the best scholar of his master. Maso Porro, Michelagnolo Urbani, both natives of Cortona, and Batista Borro of Arezzo, were trained in the same school, and were afterwards employed in Tuscany and elsewhere. In ornamenting the old palace, Vasari availed himself of the assistance of two Flemish artists, Walter and George, who wrought after his designs. Celebrated equal to any artist is Valerio Profondavalle of Louvain, who settled at Milan after the middle of the sixteenth century, a man of fertile invention, and a pleasing colourist in fresco painting, but chiefly eminent in painting on glass, as we are informed by Lomazzo. Orlandi celebrates Gerardo Ornerio Frisio, and his windows executed about 1575, in the church of S. Peter at Bologna. This art afterwards declined, when custom, the arbiter of arts, by excluding it from palaces and churches, caused it gradually to be forgotten.