112 ON THE REVOLUTIONS OF 



At the present day it does not rise heliacally till more than a month 

 after the solstice. The Egyptians would have had a decided prefer- 

 ence in finding an epoch which would aiFord a coincidence between 

 the commencement of the sacred year, with that of the actual tropical 

 year ; and then they would discover that their great period should be 

 1508 sacred years, and not 1461.* We certainly do not find any 

 trace of this period of 1508 years in antiquity. 



Can we, generally speaking, defend ourselves with the idea that if 

 the Eg}T)tians had such long series of obser^-ations, and exact observ- 

 ations, their disciple Eudoxus, who studied amongst them for thirteen 

 years, would have carried a more perfect system of astronomy, maps 

 of the heavens less inaccurate, and even congruous in their different 

 parts ?t 



How was it that the precession of the equinoxes was not kno^\-n to 

 the Greeks but from the works of Hipparchus, if it had been inserted 

 in the registers of the Egyptians, and written in such manifest charac- 

 ters on the ceilings of their temples ? 



How is it that Ptolemseus, who wrote in Egypt, did not deign to 

 make use of any of the observations of the Egj^ptians } X 



Besides, Herodotus, who dwelt with them so long, says nothing of 

 these six hours v/hich they added to the sacred year, nor of that great 

 sothaic period which resulted from it. He, on the contrary, positively 

 says, that the Egyptians making their years three hundred and sixty- 

 five days, the seasons return at the same periods; so that at his time 

 there was no appearance that they had as yet suspected the necessity 

 of this quarter of a day§. Thales, who had visited the priests of 

 Egypt less than a century before Herodotus, in like manner did not 

 make knoM^n to his fellow-countrymen any other than the year of three 

 hundred and sixty-five days only ; || and,' if we reflect that the colo- 

 nies that went from Egypt, fourteen or fifteen centuries before Christ, 

 the Jews and the Athenians carried with them the lunar year ; we 

 may perhaps judge that tl;e year of three hundred and sixty-five days 

 itself did not exist in Egypt at a period so remote. 



I know that Macrobius^ attributes a solar year of three hundred 

 and sixty-five days and a quarter to the Egyptians. But this author, 

 comparatively modern, and who lived long after the fixed year of Alex- 



* See Laplace, Systeme du Monde, 3d. edit. p. 17, and Annuaire of 1818. 



■f See M. Delambre, on the inaccuracy of the determination of the Sphere, by 

 Eudoxus, in the 1st vol. of his History of Ancient Astronomy, p. 120, et. seq. 



X See M. Delambre's Preliminary Discourse on the History of the Astronomy of 

 the Middle Age, p. 8, et seq. 



§ Euterpe, ch. iv. 



II Diog. Laert. lib 1, inThalet 

 11 Saturnal, lib. 1, ch. sv. 



