The ancients possessed a species of bastard emerald, found in vast blocks, so that we read of an emerald obelisk in Egypt, which, though consisting of but four pieces, rose to the height of sixty feet.[[844]] Of this stone, probably, was the famous pillar which adorned the entrance of the temple of Heracles at Tyre.[[845]] Of real emeralds the largest known does not exceed six inches in length, and two in diameter. It may be observed, that much pains and labour were expended in bringing the emerald to its lustre.[[846]]
The lyncurios or modern hyacinth is enumerated among the seal gems.[[847]] Its colour is that of flame with an intermixture of deep red, though it is sometimes found of a full saffron hue, or even resembling amber. It has by several writers been supposed to be the tourmaline. The lyncurios was exceedingly hard and difficult to work. They likewise cut and engraved for seals the amber, which Theophrastus describes as a native mineral; the hyaloides, the omphax, the crystal,[[848]] the sardonyx, the agate, the onyx, and the amethyst.[[849]] A gem of extraordinary beauty was once found in the gold mines of Lampsacos, which, having been engraved by a Tyrian lapidary, was presented to the Persian King.[[850]]
Respecting the various processes by which precious stones were engraved, the ancients have left us but a few scattered hints. It appears certain, however, that they polished precious stones with emery,[[851]] and possessed the lapidary’s wheel, with all the finer tools at present in use, including the diamond point,[[852]] which there is reason to believe they likewise fixed on the wheel.[[853]] At any rate, they contrived with the instruments they possessed to engrave figures, as of lions, heroes, bacchantes, caryatides, trophies,[[854]] both in relief and intaglio, which for beauty and delicacy have never yet been equalled. It was at one time a question whether or not they were acquainted with the microscope,[[855]]—though how they could engrave without it figures which we require its assistance distinctly to perceive, seems somewhat difficult to comprehend. The gem, for example, called the seal of Michael Angelo, in the French king’s cabinet, though it does not exceed half an inch in diameter, contains fifteen figures most elaborately[elaborately] wrought.[[856]] A private gentleman at Rome possessed a wolf’s tooth on which was a representation of the twelve gods.[[857]] Cicero commemorates an individual who had written the whole Iliad in characters so minute and in so small a compass, that it could be contained in a walnut-shell.[[858]] Myrmecides, the Milesian, and Callicrates, the Lacedæmonian, manufactured ivory chariots so small, that they could be covered with the wing of a fly; and wrote two verses in gold letters on a grain of sesame.[[859]]
We find mention, however, of burning-glasses as early as the age of Socrates;[[860]] and a number of lenses, more powerful than those employed by our own engravers, have been found among the ruins of Herculaneum.[[861]] We may here, also, remark by the way, that the Greek astronomers appear to have been acquainted with the telescope.[[862]]
[632]. Demosth. in Olymp. § 3. Athen. i. 33. Poll. vii. 177.
[633]. Herod. iii. 20. Pignor. De Serv. 192. Schol. Aristoph. Acharn. 1015. 1027. Athen. xv. 39. Poll. x. 119.
[634]. Lucian. Amor. 39.
[635]. Horat. Carm. ii. 723. Dœring, however, supposes vessels in the shape of shells to be meant.
[636]. Poll. x. 126.