ASrRONO MY of the BRAHMINS. 159 



28. This laft is one of the few coincidences between the aftro- 

 nomy of India and of Europe, which their ingenious hiftorian 

 has left for others to obferve. Indeed, fince he wrote, every 

 argument, founded on the moon's acceleration, has become 

 more worthy of attention, and more conclufive. For that ac- 

 celeration is no longer a mere empyrical equation, introdviced 

 to reconcile the ancient obfervations with the modern, nor a 

 fadt that can only be accounted for by hypothetical caufes, fuch 

 as the refinance of the ether, or the time neceflary for the 

 tranfmifhon of gravity ; it is a phenomenon, which M. de la 

 Place has *, with great ability, deduced from the principle of 

 univerfal gravitation, and fhewn to be neceflarily connedled 

 with the changes in the eccentricity of the earth's orbit, dif- 

 covered by M. de la Grange ; fo that the acceleration of the 

 moon is indiredly produced by the adion of the planets, which 

 alternately increafing and diminifhing the faid eccentricity, fub- 

 jedls the moon to different degrees of that force by which the 

 fun diflurbs the time of her revolution round the earth. It is 

 therefore a periodical inequality, by which the moon's motion, 

 in the courfe of ages, will be as much retarded as accelerated j 

 but its changes are fo flow, that her motion has been conftant- 

 ly accelerated, even for a longer period than that to which the 



obfervations of India extend. 



A 



bles be = na, then ma — na — 9(j(x+)), or x+y — := J^-'P; ■" ''^^ prefent 



i 

 cafe. It is certain, therefore, that whatever fuppofition be made with-re(peft to the inter- 

 val between x and j), their fum muft always be the fame, and muft amount to 5219 years. 

 But that, that interval may be long enough to give the mean motions with esaftneft, 

 it can fcarcely be fuppofed lefs than 2000 years ; and, in that cafe, x ~ 3609 years, 

 which therefore is its leaft value. But if 3609 be reckoned back from 1 700, it goes 

 up to 1909 years before Christ, nearly, as has been faid. 



It muft be remembered, that what is here inveftigated is the limit, or the moft mo- 

 dern date poffible to be affigned to the obfervations in queftion. The fuppofition that 

 x—y ■=. a, is the moft prob,ible of all, and it gives x — 4S01, which correfponds to 

 the beginning of the Calyougham. 



* Mem. Acad, des Scien. 1786, p. 235, &c. 



