(Ἵππαρχος). We must give a few words to the explanation of our reason for deferring all such account of Hipparchus as his fame requires to another article. The first and greatest of Greek astronomers has left no work of his own which would entitle him to that character: it is entirely to Ptolemy that our knowledge of him is due. In this respect, the parallel is very close between him and two others of his race, each one of the three being the first of his order in point of time. Aesop and Menander would only have been known to us by report or by slight fragments, if it had not been for Phaedrus and Terence: it would have been the same with Hipparchus if it had not been for Ptolemy. Had it happened that Hipparchus had had two names, by the second of which Ptolemy, and Ptolemy only, had referred to him, we should have had no positive method of identifying the great astronomer with the writer of the commentary on Aratus. And if by any collateral evidence a doubt had been raised whether the two were not the same, it would probably have been urged with success that it was impossible the author of so comparatively slight a production could have been the sagacious mathematician and diligent observer who, by uniting those two characters for the first time, raised astronomy to that rank among the applications of arithmetic and geometry which it has always since preserved. This is the praise to which the Hipparchus of the is entitled; and as this can only be gathered from Ptolemy, it will be convenient to refer the most important part of the account of the former to the life of the latter; giving, in this place, only as much as can be gathered from other sources. And such a course is rendered more desirable by the circumstance that the boundary between the discoveries of Hipparchus and those of Ptolemy himself is in several points a question which can only be settled from the writings of the latter, if at all.

Strabo, Suidas, &c., state that Hipparchus was of Nicaea, in Bithynia; and Ptolemy (De Adpar. Inerrant. sub fin.), in a list in which he has expressly pointed out the localities in which astronomers made their observations, calls him a Bithynian. But the same Ptolemy (Syntax. lib. v. p. 299, ed. Halma) states that Hipparchus himself has noted his own observation of the sun and moon, made at Rhodes in the 197th year after the death of Alexander. Hence some have made the Rhodian and the Bithynian to be two different persons, without any reasonable foundation. There is a passage in the (lib. iii. p. 60, ed. Halma), from which Delambre (Astron. Anc. Disc. Prel. xxiv. and vol. ii. p. 108) found it difficult to avoid inferring that Ptolemy asserted Hipparchus to have also observed at Alexandria, which had been previously asserted, on the same ground, by Weidler and others. But he afterwards remembered that Ptolemy always supposes Rhodes and Alexandria to be in the same longitude, and therefore compares times of observation at the two places without reduction.

As to the time at which Hipparchus lived, Suidas places him at from B. C. 160 to B. C. 145, but without naming these epochs as those of his birth and death. Of his life and opinions, independently of the astronomical details in the Syntaxis, we know nothing more than is contained in a passage of Pliny (H.N. 2.26), who states that the attention of Hipparchus * It was a similar circumstance which gave as remarkable an impulse to the astronomical career of Tycho Brahe, whose merits, as far as practical astronomy is concerned, much resemble those of Hipparchus. It is frequently stated that both were originally led to astronomy by the sight of new stars, which is certainly not true of the former, nor have we any reason to infer it from what Pliny says of the latter. was first directed to the construction of a catalogue of stars by the appearance of a new star, and a moving one (perhaps a comet of unusually star-like appearance). Hence he dared, rem Dco improbam, to number the stars, and assign their places and magnitudes, that his successors might detect new appearances, disappearances, motion, or change of magnitude, coelo in haereditate canctis relicto. Bayle has a curious mistake in the interpretation of a part of this passage. He tells us that Hipparchus thought the souls of men to be of celestial origin, for which he cites Pliny as follows: " Idem Hipparchus nunquam satis laudatus, ut quo nemo magis approbaverit cognationem cum homine siderunli, animasque nostras partem esse coeli." This means, of course, that Pliny thought that no one had done more than Hipparchus to show the heavenly origin of the human mind.