Theophilus, writing a few generations later, probably in Germany, knew nothing of this cemetery glass. He describes, however, the process by which the Byzantine Greeks made their gold mosaics by sprinkling a layer of powdered glass over the gold leaf covering the surface of the tesseræ; this coating was then fused on. But this was an enameller’s process, and the coating must have consisted of a somewhat fusible glass, perhaps containing lead. The Greeks employed, he tells us, a similar process in decorating their glass cups.
Signor Andrea Rioda, the art director of the Impresa Venezia-Murano, tells me that in the case of some clever imitations of fondi d’oro made by his firm, the gold leaf was fixed upon a thickish sheet of glass, a thinner sheet was then placed over it, and the whole heated to the softening-point. A third method has been adopted in the preparation of some experimental imitations made by Mr. Westlake: that gentleman soldered together the two sheets of glass round the edges only, by means of a flux.
In the general treatment of the figure, and in the choice of the subject, we are reminded in the case of this cemetery glass of the reliefs upon contemporary Christian sarcophagi—that is to say of the more rudely executed of these reliefs. But among these fondi d’oro there is a small class of portrait heads, highly finished by means of a sort of pointillé or stipple process, which are of a somewhat superior artistic merit. In these circular medallions—miniatures, we might call them[[62]]—the large eyes, the small mouth, and a peculiar affable but sad and ‘worn-out’ expression, remind us of the portrait heads on late mummy cases brought from the Fayum. These highly finished miniatures are probably of somewhat earlier date than the typical glass from the catacombs.
We find occasionally in this cemetery glass a sparing use of coloured enamels, above all on the draperies.[[63]] In others the outlines, it would seem, were cut into the glass and filled up with coloured pastes, a process of great technical interest; I have not, however, myself seen an example of such work.
A few rare pieces with Jewish symbols have been found, but not in any case, I think, from Jewish cemeteries. We see the scrolls of the law lying on the aron, and the seven-branched candlestick. I have already pointed out that at this time in Rome the working of glass was very probably to some extent in the hands of Jews and Judaising Christians.[[64]]
The cemetery glass dates, it would seem, from the fourth and from the first half of the fifth century, but some of the finer pieces may be a little older. The disasters of the fifth century and the rapid decline of Rome after the time of Honorius help to explain the total extinction of this genre soon after the latter period.
Apart from these gilt medallions, the examples of glass that may be classed as early Christian present no special feature. There is in the British Museum a series of cameo medallions, some of hæmatinum and others of sapphire-blue glass paste. In these the treatment of the figures—the Virgin and Child and St. George (or possibly St. Theodore) are the favourite subjects—is quite Byzantine in character. In the Vatican Museum, among many other such medallions, are some cast from the same moulds as our English examples. The little pendeloques of stamped glass remind one of the late Roman and Saracenic glass weights found in Egypt; they have formed probably parts of a necklace, or they may have been attached to drapery.
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.