days. days. Mercury 87·9705 87·9692580 Venus 224·7 224·7007869 Earth 365·2564 365·2563612 Mars 686·99 686·9796458 Jupiter 4332·65 4332·5848212 Saturn 10759·4 10759·2198174 Somerville, p. 358. Herschel, p. 416. [143] “‘mundo;’ hoc est, cœlo inerrantium stellarum.” Hardouin, in Lemaire, ii. 242. [144] Our author supposes, that the spectator has his face directed towards the south, as is the case with the modern observers. We are, however, informed by Hardouin, that this was not the uniform practice among the ancients; see the remarks of Alexandre in Lemaire, ii. 242, and of Marcus in Ajasson, ii. 269. [145] The _constant revolution_ refers to the apparent daily motion; the _opposite direction_ to their annual course through the zodiac. Ptolemy gives an account of this double motion in his Magna Constructio, i. 7. [146] For the exact period, according to Somerville and Herschel, see note [142], p. 27. [147] Aristotle informs us, that Mars was also called Hercules or Pyrosis; De Mundo, cap. ii. p. 602. See also Apuleius, De Mundo, § 710. Hyginus is said by Hardouin to give the name of Hercules to the planet Mars, but this appears to be an inaccuracy; he describes the planet under its ordinary appellation; lib. ii. p. 62; and ii. 78, 9. [148] Cicero, speaking of the period of Mars, says, “Quatuor et viginti mensibus, sex, ut opinor, diebus minus;” De Nat. Deor. For the exact period, see note [142], p. 27. [149] “Sed ut observatio umbrarum ejus redeat ad notas.” According to the interpretation of Hardouin, “Ad easdem lineas in solari horologio.” Lemaire, ii. 243. [150] This is an example of the mode of computation which we meet with among the ancients, where, in speaking of the period of a revolution, both the time preceding and that following the interval are included.