The art of making glass, which dates in Egypt at least as far back as the first Theban dynasty,[367] was invented in Mesopotamia, or imported into it, at a very early period. No glass objects have been found in the oldest Chaldæan tombs, but they abound in the ruins of the Assyrian palaces. A great number of small glass bottles, resembling the Greek _alabastron_ or _aryballos_ in shape,[368] have been dug up; many of them have been made brilliantly iridescent by their long sojourn in the earth.[369] A vase found by Layard at Nimroud, and engraved with Sargon’s name just below the neck, is generally quoted as the oldest known example of transparent glass (see Fig. 190).[370] It has been blown solid, and then the inside cut out by means of an instrument which has left easily-visible traces of its passage; this instrument was no doubt mounted on a lathe. Sir H. Layard believes, however, that many of the glass objects he found are much older, and date from the very beginning of the Assyrian monarchy, but their material is opaque and coloured.[371] Some bracelets of black glass, which were dug up at Kouyundjik, prove that common jewelry was sometimes made of that material; glass beads, sometimes round, sometimes flat, have also been found.[372] A glass cylinder or tube, of unknown use, was found by Layard at Kouyundjik; it is covered with a decoration made up of lozenges with a concave surface (Fig. 191). [Illustration: FIG. 190.--Glass vase or bottle. Height 3½ inches. British Museum.] [Illustration: FIG. 191.--Glass tube. Height 8¾ inches. British Museum.] It is curious that no cylinders or cones of terra-cotta or glass have come down to us from the Assyro-Chaldæan period. Clay was doubtless thought too common a material for such uses, and as for glass, they had not yet learnt how to make it a worthy substitute for _pietra dura_, as the Greeks and Romans did in later years.