[165] Origin. xvi. 7. [166] Goguet, ii. p. 111. Fabricii Biblioth. Græca. vol. i. p. 70. [167] Keyssler, i. pp. 17 and 441. [168] Lib. xxxvii. cap. 7. [169] De Lapid. § 61. [170] [This stone acquired its name from its being much used in ornaments by the Incas or Princes of Peru.] [171] De la Vega, ii. 28. [172] Montamy in Abhandlung von den Farben zum Porzellan, Leipzig, 1767, 8vo, p. 222, asserts that he saw, in a collection of antiquities, glass mirrors which were covered behind only with a black foil. [173] Lib. xxxvi. cap. 26, p. 758. [174] Lib. xxxiii. cap. 9, p. 627. [175] Trebell. Pollio, Vita Gallien. cap. 12. [176] Chemical Essays, vol. iv. p. 246. [177] Plin. lib. xxxiii.: Æs inaurari argento vivo, aut certe hydrargyro, legitimum erat. The first name here seems to signify native quicksilver, and the second that separated from the ore by an artificial process. [178] Hist. Nat. Supplem. i. p. 451. [179] Stob. Eclog. Antv. 1575, fol. p. 56. [180] De Placitis Philos. ii. cap. 20. [181] In Aratum, cap. 19. [182] Lib. i. cap. 8. [183] It is undoubtedly certain, that ὕαλος, which is translated _vitreous_ or _glassy_, means any smooth polished body capable of reflecting rays of light. Originally it signified a watery body; and because watery bodies have a lustre, it was at length used for glass. See Salmas. ad Solin. p. 771. [184] More observations respecting the opinion of Philolaus may be found in the edition of Plutarch’s work De Placitis Philosophorum by Ed. Corsinus, Flor. 1750, 4to, p. 61, and p. 23. [185] Professor Heeren having given me his opinion on this passage of Stobæus, I shall here insert it for the satisfaction of the learned reader. The critics, says he, will hardly be persuaded that the words καὶ τὸ ἀπ’ αὐτοῦ πυροειδὲς κατὰ τὸ ἐσοπτροειδὲς are correct, as they can be translated different ways. With regard to the explanation of the matter, I build only on the plain meaning of the words. The author tells us, that Philolaus thought the sun to be a mirror; but we must conclude that he speaks of a mirror such as were then in use; a smooth plate of metal, and not a globe. In this case the first explanation of a glass globe falls to the ground. This is confirmed by Eusebius, who calls it ὑαλοειδὴς δίσκος, though it is possible that the latter word may be a gloss added by some grammarian, or by Eusebius himself. If we enter further into the explanation, we must adopt the plain idea, that the rays of the sun fall upon this plate, and are reflected to us. I am however of opinion, that ὕαλος ought to be translated _glass_, ὑαλοειδὴς _glassy_ or _vitreous_; for the intention of Philolaus evidently was to define the substance of the sun’s body. The result of the whole is, Philolaus considered the sun as a plain plate of glass which reflected the rays or brightness of the æthereal fire. But that he was acquainted with a proper glass mirror does not thence follow with certainty.