186 THEORY OF THE EARTH. 



ended in the 138th year of the Christian era*. 

 It had consequently commenced in the 1322d be- 

 fore Christ, and that which preceded it in the 

 2782d. In fact, the calculations of M. Ideler 

 shew, that Sirius was heliacally risen on the 20th 

 July of the Julian year 139, a day which corres- 

 ponded that year to the first of Thot, or the first 

 day of the Egyptian sacred year f . 



But not only is the position of the sun, with 

 relation to the stars of the ecliptic, or the side- 

 real year different from the tropical year, on ac- 

 count of the precession of the equinoxes. The he- 

 liacal year of a star, or the period of its heliacal 

 rising, especially when it is distant from the 

 ecliptic, differs still from the sidereal year, and 

 differs in various degrees according to the lati- 

 tudes of the places where it is observed. What 

 is very singular, however, and the observation has 

 already been made by Bainbridge J and Father 

 Petau , it happens, by a remarkable concurrence 



* The whole of this system is developed by Censorinus, 

 De Die Natali, cap. tv'ni. and xxi. 



t Ideler. Historical Researches regarding the Astrono- 

 mical Observations of the Ancients. M. Raima's transla- 

 tion, at the end of his Canon de Ptolomee, p. 32. et seq. 



J Bainbridge, Canicul. 



Petau, Var. Dios. lib* v. cap. vi. p. 108. Also, La 

 Nanze, Acad. de Bell. Lett. t. xiv. p. 346. 



