The Greeks knew nothing of the art, though they possessed the substance. Prometheus, in Eschylus, claims the honour of almost every invention--glass is not enumerated among his titles to the hatred of Jupiter. Socrates, in “The Clouds,” tricks a bum-bailiff out of his wit by means of a burning-glass.[114] From the Scholiast we learn, that these were sold at the apothecaries. This burner may now seem of another substance, of which the Phœnicians had possession--amber. I have seen it so used on the coast of the Baltic, being formed in the most primitive manner by rubbing between the palms of the hands. Amber was supposed to attract the sun’s rays, as it did various substances, whence its name, ἔλεκτρον. The word was also applied to glass,[115] from its possessing a similar quality. There may be more in the association than we have yet discovered. Pliny mentions the magnet as used in the preparation of glass. The Tyrians employed glass as artillery; they discharged what was called “melted sand” at Alexander’s troops in storms which inflicted torture, and carried dismay and agonies against which no defensive armour could avail. The Venetians, following in their steps, likewise made glass their artillery. The first shells, and perhaps the most effectual, were of glass; they are still to be seen used as ink-bottles. But the art seems to have extended from burning glasses to microscopes and telescopes, or they must have had eyes differently constituted from ours; for without such aid we could not make out valleys and mountains in the Moon; the milky-way[116] to be composed of stars; or count, as there is reason to believe they had done, the satellites of Jupiter and Saturn: and, supposing reflectors, and not lenses, were employed to survey the heavens, we can hardly escape from acknowledging their claim to microscopes and magic lanterns.[117] Their gems could not have been engraved without such aid; indeed, we require glass to make out the figures of some of them.[118] Eye-glasses we know they had, from Nero, who, being short-sighted, used one in the amphitheatre: it is called an emerald. One of the personages on the Greek stage had eyes of different colours, which was represented in his mask, and of course by coloured glasses. All these were the “wares of Tyre.” In after times the manufacture of glass was transferred to Rome; but in the early period the Phœnicians must have supplied glass to Greece and Italy, as they did to Egypt, Assyria, Spain, and Africa.