I shall now notice the mosaic work of Florence. It differs entirely from Roman mosaic, being composed of stones inserted in comparatively large masses; it is called work in _pietra dura_. The stones used are all more or less of a rare and precious nature. In old specimens the most beautiful works are those in which the designs are of an arabesque character. The most remarkable specimen of this description of pietra dura is an octagonal table in the _Gubinetto di Baroccio_, in the Florence Gallery. It is valued at £20,000 sterling, and was commenced in 1623 by Jacopo Detelli, from designs by Ligozzi. Twenty-two artists worked upon it without interruption till it was terminated in the year 1649. Attempts at landscapes, and the imitation of natural objects, were usually failures in former times, mere works of labour, which did not attain their object; but of late works have been produced in this art, in which are represented groups of flowers and fruit, vases, musical instruments, and other compatible objects, with a truth and beauty which excite the utmost admiration and surprise. These pictures in stone are, however, enormously expensive, and can only be seen in the palaces of the great. Two tables in the Pilazzo Pitti are valued at £7,000, and this price is by no means excessive. These are of modern design, on a ground of porphyry, and ten men were employed for four years on one of them, and a spot is pointed out, not more than three inches square, on which a man had worked for ten months. But Florentine mosaic, like that of Rome, is not merely used for cabinets, tables, or other ornamental articles; the walls of the spacious chapel which is used as the burial-place of the reigning family at Florence are lined with pietra dura, realising the gem-encrusted halls of the Arabian tales. Roman mosaic, as we have seen, is of great value as an ally to art; but Florentine mosaic can have no such pretensions, and time and money might be better bestowed. The effect is far from pleasing in the chapel I have alluded to, and I think that the art might be advantageously confined to the production of small ornaments, for which it is eminently adapted.--_The Civil Engineer and Architect’s Journal._ SEALS OF IRISH CHIEFS. An Essay read at a Meeting of the Royal Irish Academy, by George Petrie, R.H.A., M.R.I.A.