Formerly there was in Venice another "chair of St. Peter," of which there is a sketch from a photograph in Mrs. Oliphant's "Makers of Venice." It is said to have been a present from the Emperor Michael, son of Theophilus (824-864), to the Venetian Republic in recognition of services rendered, by either the Doge Gradonico, who died in 864, or his predecessor, against the Mahommedan incursions. Fragments only now remain, and these are preserved in the Church of St. Pietro, at Castello. There is also a chair of historic fame preserved in Venice, and now kept in the treasury of St. Mark's. Originally in Alexandria, it was sent to Constantinople and formed part of the spoils taken by the Venetians in 1204. Like both the other chairs, this was also ornamented with ivory plaques, but these have been replaced by ornamental marble. The earliest of the before-mentioned chairs, namely, the one at Ravenna, was made for the Archbishop about 546 to 556, and is thus described in Mr. Maskell's "Handbook on Ivories," in the Science and Art series:--"The chair has a high back, round in shape, and is entirely covered with plaques of ivory arranged in panels carved in high relief with scenes from the Gospels and with figures of saints. The plaques have borders with foliated ornaments, birds and animals; flowers and fruits filling the intermediate spaces. Du Sommerard names amongst the most remarkable subjects, the Annunciation, the Adoration of the Wise Men, the Flight into Egypt, and the Baptism of Our Lord." The chair has also been described by Passeri, the famous Italian antiquary, and a paper upon it was read by Sir Digby Wyatt, before the Arundel Society, in which he remarked that as it had been fortunately preserved as a holy relic, it wore almost the same appearance as when used by the prelate for whom it was made, save for the beautiful tint with which time had invested it. Long before the general break up of the vast Roman Empire, influences had been at work to decentralise Art, and cause the migration of trained and skilful artisans to countries where their work would build up fresh industries, and give an impetus to progress, where hitherto there had been stagnation. One of these influences was the decree issued in A.D. 726 by Leo III., Emperor of the Eastern Empire, prohibiting all image worship. The consequences to Art of such a decree were doubtless similar to the fanatical proceedings of the English Puritans of the seventeenth century; and artists, driven from their homes, were scattered to the different European capitals, where they were gladly received and found employment and patronage. It should be borne in mind that at this time Venice was gradually rising to that marvellous position of wealth and power which she afterwards held.