568 ON THE ANTIQUITY OF 



57. The most correct and certain mode of inves- 

 tigating the antiquity of ///?2f/« astronomical works, 

 is by comparing the positions and motions of the 

 planets computed from thence, with those deduced 

 from accurate European tables. For, it must be 

 obvious that every astronomer, let the principle of 

 his system be what it will, whether real or artificial, 

 must endeavour to give the true positions of the 

 planets in his own time ; or at least as near as he 

 can, or the nature of his system will permit : other- 

 wise his labour would be totally useless. 1 here fore, 

 having the positions and motions of the Sun, Moon, 

 and planets, at any proposed instant of time, given 

 by computation from any original Hindu system ; 

 and having also their positions and motions deduced 

 from correct European tables for the same instant ; 

 we can from thence, determine the point or points 

 of time back, when their respective positions were 

 precisely the same by both. 



58. According to the ^y^/n/^ Siddlian fa, the mo- 

 tion of the Moon's apogee in 100 years of 265'^^- 15^°- 



31' 31" 24'" each ='-^^'^^ = 11 rev. 3 18" 21' 30" 



ByDE LA Laisde's tables for 



the same space of time, 



in the ///?;r/z^ sphere, =11 rev. 3 17 39 19,1 

 Difference, the former greater by 42 J 0,9 



Now, supposing the author of the 6'ujya Siddhantay 

 to have accurately determined the position of the 

 Moon's apogee, when he wrote that work ; it 

 must follow, that at the expiration of one hundred 

 Hindu years from that time, the computed place of 

 tlie apogee, would exceed the true by 42' 10,"9 ; and 

 at the end of two centuries, it would be double that 

 quantity ; so that the difference between the true, 

 and. computed places, has been ever since encreasing 

 in that proportion. Therefore, in order to ascertain 

 the age of the Kiurija Sidd/ianla, we must find what* 



the 



