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which actually moves over the celestial vault; for hesays, “ If I beheld the sun when it shined or themoon walking in brightness ” (Job xxxi. 26) ; and therecognition of the sun’s annual circuit of the heavensmost probably preceded the discovery of the motionsof the planets. Be this, however, as it may, astro-nomers must quite early have ascertained that amongthe more conspicuous orbs not one travels so quicklyover the celestial vault as the moon. Accordingly,we find that even in the very earliest ages of astro-nomy the moon was regarded as the orb whichtravels nearest to the earth; and in the system ofPythagoras , in which musical tones were supposedto be produced by the revolution of the spheresbearing the planets, we find the neate, or highesttone of the celestial harmonies, assigned to themoon.
Whether the Chaldsean astronomers ever ascertainedthe moon’s distance observationally, is a question wehave no means of answering satisfactorily. If they did,it is probable that the determination arose from thecareful study of the moon’s peculiarities of motion,—undertaken with the object of rendering the predictionof eclipses more trustworthy. So far as is known,however, the first actual determination of the moon’sdistance (as compared with the dimensions of theearth’s globe) must be ascribed to the astronomersof the Alexandrian school. Aristarchus of Samos (b.c. 280) had attempted to compare the distances ofthe sun and moon by a method of observation