Hindu Astronomical Tables. 25 



These epochs are connected with the mean motions of the sun, 

 moon, and planets, in such a manner, that, setting out from the 

 position which the Indian tables assign to all the stars at this 

 second epoch, and reascending to the first by means of these 

 tables, the general conjimction which they suppose at this pri- 

 mitive epoch is found. Bailly, the celebrated astronomer, already 

 alluded to, endeavours, in his Indian Astronomy, to prove that 

 the first of those epochs is founded on observation. Notwith- 

 standing all the arguments are brought forward with that perspi- 

 cuity he knew so well to bestow on subjects the most abstract, 

 I am still of opinion, that this period was invented for the pur- 

 pose of giving a common origin to all the motions of the heavenly 

 bodies in the zodiac. Our last astronomical tables being render- 

 ed more perfect by the comparison of theory with a great num- 

 ber of observations, do not permit us to admit the conjunction 

 supposed in the Indian tables ; in this respect, indeed, they made 

 much greater differences than the errors of which they are still 

 susceptible, but it must be admitted that some elements in the 

 Indian astronomy have not the magnitude which they assigned 

 to them, until long before our era ; for example, it is necessary 

 to ascend 6000 years back to find the equation of the centre of 

 the sun. But, independently of the errors to which the Indian 

 observations are liable, it may be observed, that they only con- 

 sidered the inequalities of the sun and moon relative to eclipses, 

 in which the annual equation of the moon is added to the equa- 

 tion of the centre of the sun, and augments it by a quantity 

 which is very nearly the difference between its true value and 

 that of the Indians. Many elements, such as the equation of 

 the centre of Jupiter and Mars, are very different in the Indian 

 tables from what they must have been at their first epoch. 



" A consideration of all these tables, and particularly^the im- 

 possibility of the conjunction at the epoch they suppose, prove, 

 on the contrary, that they have been constructed, or at least rec- 

 tified, in modern times. This also may be inferred from the 

 mean motions which they assign to the moon, with respect to its 

 perigee, its nodes, and the sun, which, being more rapid than 

 according to Ptolemy, indicate that they are posterior to this as- 

 tronomer ; for we know, by the theory of universal gravitation, 

 that these three motions have accelerated for a great number of 



