The best known examples of this glass veneering come from the ruins of a building some four miles to the north of Rome, generally known as the Villa of Lucius Verus; there are many fine pieces from this source in our museums. In private houses this veneering of glass was above all in favour for the bath-chamber. ‘_Vitro absconditur camera_’ says Seneca, instancing this practice as a sign of the advancing luxury of the age. In the earlier methods each slab or tile is built up of pieces of glass of geometrical outline; in rarer cases the adjacent pieces have been fused together or again pressed into a base of glass by a plan similar to that formerly used in Egypt. But when the individual pieces of glass have been cut into shapes and then fitted together to form the design, we have the _opus sectile_ of the Romans. We are here dealing with something nearly approaching in character to a true mosaic, and therefore outside the limits we have given ourselves. But it is impossible to pass over without mention the marvellous examples of this class of work which covered the walls of the basilica erected at Rome by Junius Bassus, consul in the year 317. Although this building no longer exists, important remains of the _opus sectile_ which once covered its walls are preserved in a private palace at Rome, and some smaller compartments may be seen in the Church of St. Antonio Abbate on the Esquiline. These have been described in a paper read by the late Mr. Nesbitt before the Society of Antiquaries (_Archæologia_, vol. xlv.; see especially the coloured plate XVIII.). The main subjects, indeed, and the ground are executed chiefly in coloured marbles, but for us the most interesting part is the band representing embroidery below the large picture of Hylas and the Nymphs. This frieze of small figures is formed entirely of glass, and it will be noticed that in this part both the subject and the treatment are Egyptian. We have here the copy of a wall-hanging—probably of one of the heavy embroidered _tapetia Alexandrina_. It must be borne in mind that although this work was nearly contemporary with the Christian mosaics of the time of Constantine, the designs must, in part at least, have been copied from some earlier composition. The frieze of figures indeed takes us back to the Egyptian renaissance of Hadrian’s time. The glass of which the larger plaques of this Roman veneer were made was probably poured out upon an even surface, rolled while hot, and at times, but not always, subsequently polished. It may be regarded as a primitive form of what the French call _verre coulé_, a term which includes our modern plate-glass. The thick heavy glass that the Romans used for their slit-like windows belongs to the same class; it is well known that slabs of considerable size have been found in position at Pompeii, but we are not concerned here with this purely practical application of the material.[31]