[189] Hipparchus is generally regarded as the first astronomer who prosecuted the science in a regular and systematic manner. See Whewell, C. 3. p. 169 _et seq._, 177-179. He is supposed to have made his observations between the years 160 and 125 B.C. He made a catalogue of the fixed stars, which is preserved in Ptolemy’s Magn. Const. The only work of his now extant is his commentary on Aratus; it is contained in Petau’s Uranologie. We find, among the ancients, many traces of their acquaintance with the period of 600 years, or what is termed the great year, when the solar and lunar phænomena recur precisely at the same points. Cassini, Mem. Acad., and Bailly, Hist. Anc. Astron., have shown that there is an actual foundation for this opinion. See the remarks of Marcus in Ajasson, ii. 302, 303. [190] Seneca, the tragedian, refers to this superstitious opinion in some beautiful verses, which are given to the chorus at the termination of the fourth act of the Thyestes. [191] We have an account of this event in Thucydides, Smith’s trans. ii. 244, and in Plutarch, Langhorne’s trans. iii. 406. It is calculated to have happened Aug. 27th, 413 B.C.; Brewster, _ut supra_, p. 415, 421. [192] The elegant lines of Ovid, in his Fasti, i. 297 _et seq._, express the same sentiment: “Felices animos, quibus hoc cognoscere primis,” &c. [193] I have already remarked upon the use of this term as applied to the eclipses of the moon in note [164], p. 31. [194] According to the remarks of Marcus, it appears probable that this sol-lunar period, as it has been termed, was discovered by the Chaldeans; Ajasson, ii. 306, 307. [195] “coitus.” [196] “Hoc enim periodo (223 mensium) plerumque redeunt eclipses, non multum differentes, denis tamen gradibus zodiaci antecedentes;” Kepler, as quoted by Alexandre, in Lemaire, ii. 238. [197] The terms “sub terra” and “superne” are interpreted, by most of the commentators, below and above the horizon respectively; see Marcus in Ajasson, ii. 307. [198] “globo terræ obstante convexitatibus mundi.” The term _convexus_, as applied to the heavens, or visible firmament, simply signifies _arched_; not opposed to _concave_, like the English word _convex_. [199] This point is discussed by Ptolemy, Magn. Const. vi. 6; “De distantia eclipticorum mensium.” See also the remarks of Hardouin in Lemaire, ii. 260, 261; and of Poinsinet, i. 67. [200] These are styled horizontal eclipses; they depend on the refractive power of the atmosphere, causing the sun to be visible above the horizon, although it is actually below it. Brotier states, that eclipses of this description occurred on the 17th July, 1590, on the 30th November, 1648, and on the 16th January, 1660; Lemaire, ii. 260. [201] This is supposed to have been in the year 72 of our æra, when it is said that the sun was eclipsed, in Italy, on the 8th, and the moon on the 22nd of February; see Hardouin and Alexandre, in Lemaire, ii. 261.