[165] We have some interesting remarks by Marcus respecting Endymion, and also on the share which Solon and Thales had in correcting the lunar observations; Ajasson, ii. 288-290. [166] “Lucem nobis aperuere in hac luce.” [167] “Cardo.” [168] Astronomers describe two different revolutions or periods of the moon; the synodical and the sidereal. The synodical marks the time in which the moon passes from one conjunction with the sun to the next conjunction, or other similar position with respect to the sun. The sidereal period is the time in which the moon returns to the same position with respect to the stars, or in which it makes a complete revolution round the earth. These numbers are, for the synodical period, 29ᵈ 12ʰ 44ᵐ 2·87ˢ, and for the sidereal, 27ᵈ 7ʰ 43ᵐ 11·5ˢ; Herschel, pp. 213, 224. [169] Our author, as Marcus remarks, “a compté par nombres ronds;” Ajasson, ii. 291; the correct number may be found in the preceding note. [170] It was a general opinion among the ancients, and one which was entertained until lately by many of the moderns, that the moon possessed the power of evaporating the water of the ocean. This opinion appears to have been derived, at least in part, from the effect which the moon produces on the tides. [171] “quantum ex sole ipsa concipiat;” from this passage, taken singly, it might be concluded, that the author supposed the quantity of light received by the moon to differ at different times; but the succeeding sentence seems to prove that this is not the case; see the remarks of Alexandre in Lemaire, ii. 249. Marcus, however, takes a different view of the subject; Ajasson, ii. 291, 292. He had previously pointed out Pliny’s opinion respecting the phases of the moon, as one of the circumstances which indicate his ignorance of astronomy, _ut supra_, ii. 245, 246. [172] This doctrine is maintained by Seneca, Quæst. Nat. lib. ii. § 5. p. 701, 702. From the allusion which is made to it by Anacreon, in his 19th ode, we may presume that it was the current opinion among the ancients.