[250] As Alexandre justly remarks, our author refers here to the aspects only of the planets, not to their phases; ii. 284.
[251] “centrum terræ;” the equator, the part equally distant from the two poles or extremities.
[252] It may be remarked, that the equinoxes did not actually take place at this period in the points mentioned by Pliny, but in the 28th degrees of Pisces and Virgo respectively; he appears to have conformed to the popular opinion, as we may learn from Columella, lib. ix. cap. 14. The degrees mentioned above were those fixed by the Greek astronomers who formed the celestial sphere, and which was about 138 years before the Christian æra. See the remarks of Marcus in Ajasson, ii. 246 & 373, 374.
[253] The same remark applies to this as to the former observation.
[254] “siderum.”
[255] The hypothesis of the author is, that the excess of moisture in the orbit of Saturn, and the excess of heat in that of Mars, unite in the orbit of Jupiter and are discharged in the form of thunder.
[256] Alexandre remarks, that Pliny mentions this, not as his own opinion, but that of many persons; for, in chap. 21, he attempts to prove mathematically, that the moon is situated at an equal distance between the sun and the earth; Lemaire, ii. 286.
[257] Marcus remarks upon the inconsistency between the account here given of Pythagoras’s opinion, and what is generally supposed to have been his theory of the planetary system, according to which the sun, and not the earth, is placed in the centre; Enfield’s Philosophy, i. 288, 289. Yet we find that Plato, and many others among the ancients, give us the same account of Pythagoras’s doctrine of the respective distances of the heavenly bodies; Ajasson, ii. 374. Plato in his Timæus, 9. p. 312-315, details the complicated arrangement which he supposes to constitute the proportionate distances of the planetary bodies.
[258] Sulpicius has already been mentioned, in the ninth chapter of this book, as being the first among the Romans who gave a popular explanation of the cause of eclipses.
[259] “Διὰ πασῶν, omnibus tonis contextam harmoniam.” Hardouin in Lemaire, ii. 287.