THEORY OF THE EARTH. 187 



in the positions, that, in the latitude of Upper 

 Egypt, at a certain epoch, and during a certain 

 number of ages, the year of Sirius was really 

 within very little of 365 days and a quarter ; so 

 that the heliacal rising of this star returned in 

 fact to the same day of the Julian year, the 20th 

 July, in the year 1322 before, and the year 138 

 after Christ *. 



From this actual coincidence, at this remote 

 period, M. Fourier, who has confirmed all these 

 accounts by new calculations, concludes, that, 

 since the length of the year of Sirius was so per- 

 fectly known to the Egyptians, they must have 

 determined it by observations made during a long 

 series of years, and conducted with great accuracy ; 

 observations which must be referred to at least 

 2500 years before the present time, and which 

 could not have been made long before or long af- 

 ter this interval of time f. 



* Petau. loc. cit. M. Ideler asserts that this concurrence 

 of the heliacal rising of Sirius also took place in 2782 be- 

 fore Christ. (Historical Researches in M. Raima's Ptolo- 

 mee, vol. iv. p. 37.) But with regard to the Julian year 

 1598 after Christ, which is also the last of a great year, Pe- 

 tau and Ideler differ much from each other. The latter 

 refers the heliacal rising of Sirius to the 22d July; the for- 

 mer to the 19th or 20th of August. 



t See, in the great work on Egypt, Antiq. Memoirs, 

 vol. 1. p. 803. the ingenious Memoir of M. Fourier, enti- 



