190 THEORY OF THE EARTH. 



of the commencement of the sacred year, with 

 that of the true tropical year, and then they would 

 discover that their great period must have heen 

 1508 sacred years, and not 1461.* Now, we 

 assuredly do not find any traces of this period of 

 1508 years in antiquity. 



In general, we may defend ourselves with the 

 idea, that, if the Egyptians had possessed so long 

 a series of observations, and of accurate observa- 

 tions too, their disciple Eudoxus, who studied 

 among them for thirteen years, would, on his re- 

 turn, have brought into Greece a system of astro- 

 nomy more perfect, and maps of the heavens less 

 erroneous, and more coherent in their different 

 parts, f How should it happen that the preces- 

 sion of the equinoxes was not known to the 

 Greeks, but through the works of Hipparchus, if 

 it had been marked in the registers of the Egyp- 

 tians, and inscribed in characters so manifest up- 

 on the ceilings of their temples ? And how comes 

 it that Ptolemy, who wrote in Egypt, should not 



* See Laplace, Systeme du Monde, 3d edition, p. 17; 

 and the Annuaire of 1818. 



t See on the Inaccuracy of the Determinations of the 

 Sphere of Eudoxus, M. Delambre, in the first volume of 

 his History of the Astronomy of the Ancients, p. 120. 

 et seq. 



2 > /X>f ,T" : - 



