ANTIQUITY OF ASTRONOMICAL WORKS. 303 



These are constructed on the principles of the European 



, Mr Bentlpy lays down this as a canon, " that the most 

 certain mode of investigating the antiquity of Hindoo astro- 

 nomical works is, by comparing the positions and motions 

 of the planets computed thence with those deduced from 

 accurate European tables ; for it must be obvious, that 

 every astronomer, be his system what it will, whether real 

 or artificial, must endeavour to give the true position of the 

 planets in his own time, or at least as near as he can or the 

 nature of his system will permit, otherwise his labour 

 would be totally useless. Therefore, havmg the positions 

 and motions of the sun, moon, and planets, at any proposed 

 instants of time, given by computation from any origmal 

 Hindoo system, and having also their positions and motions 

 deduced from correct European tables, lor the same in- 

 stant, ^y^ can thence determine the pomt or points of tune 

 back when their respective positions were precisely the same 



in both." , , . ■ 1 !,„ 



Proceeduitr on this apparently reasonable prmciple, he 

 finds the secular motion of the moon's apogee, accordmg to 

 the Surya Siddhanta, and the tables of Lalande, to be 4- 

 10 9" Now, suppose that Varaha (the real author ol the 

 Surm) had determined for his own time the position of the 

 apogee, it would follow that, at the end of 100 years, there 

 would be an error of 42' in the place of the moon ; 200 

 years after, the error would be double ; and accordmg to 

 ihis idea, the apogee must have been determined by obser- 

 vation 605 years before the epoch of 1799, that is, m 1134 



Bv like calculations on the node, he finds 580 years. The 

 equations since found by Laplace change somewhat these 

 detenninations ; besides, it is impossible to answer lor the 

 positions found by Varaha. 



By the motion of the sun's apogee, the time when the 

 observations were made on which the tables were con- 

 structed comes out 1 105 years. But the motion is so slow, 

 and so difficult to determuie, that this result ought not to be 

 reckoned with the others. 



Mercury, which separates so little from the sun, gives a 

 result with a contrary sign ; from this nothing can be de- 

 termined. 



