The early Christian engraved glass is of more importance, but it in no way differs in technique from that carved with pagan subjects; some of the vases may possibly have served as chalices for use in the service of the Eucharist. In the British Museum is a conical cup from Cologne; the figures are roughly cut with the wheel, and the subjects from the Old and New Testaments are the same as those found on contemporary sarcophagi. The design on the Podgoriza bowl,[65] perhaps the finest example of early Christian engraving on glass, shows the influence of the northern barbarians; there is a Viking air about some of the subjects. Notice especially the ship from which Jonah is being thrown, and the gaping monsters in the sea, more like dragons than whales. (See Mr. Arthur Evans’s paper in _Archæologia_, vol. xlviii.) As I have already said, the gap which exists between the later Roman and the great school of enamelled Saracenic glass of the thirteenth century can only be filled by a few scattered examples from widely distant sources. The tombs now fail us, and we are thrown back for the most part upon the treasures and relics preserved in the churches of Italy, France, and Germany. Such objects represent but one aspect of the glass produced at the time: they reflect above all the skill now acquired in staining glass so as to imitate precious stones. We shall see later that there has been preserved an interesting literary record bearing especially on such imitations. The alchemists now begin to come into touch with the glass-workers—a connection that has been maintained even to quite recent times. The Jews, too, were early occupied with the manufacture of coloured pastes, and their interest in the subject has continued, as we know, up to the present day. It would be impossible to neglect the importance of Constantinople when treating of the art of the early mediæval—the so-called dark ages. But so far as glass, in our narrower sense of the word, is concerned, there is little that can be definitely attributed to that city. For us, however, the interest of the Greek Empire lies in the fact that we have in it a common middle term with which to correlate the art of the Copts in Egypt, of the Sassanians in Persia, and at a later time, in some measure, that of the early Saracen dynasties and even of the Anglo-Saxons and the Franks in the north. At two widely separated periods the influence of Constantinople has been more directly felt. The first centres round Justinian in the sixth century; we are brought at that time into relation with the Copts and the Sassanian rulers of Persia. The other is the time of the great revival of Byzantine power in the tenth century, when, chiefly through alliances with the emperors of the Saxon house, the renewed art of the Greeks spread through Germany and even reached, not for the first time indeed, the shores of England.