126 The Rev. Dr. Wall on the Nature, Age, and Origin of the 



inadequate idea of the great clearness and ability with which they have been 

 composed. 



The main foundation of Mr. Bentley's discovery respecting the Hindoo 

 astronomy, and which he has established in the most convincing manner, is, that 

 every known system of it, excepting, indeed, those grounded upon methods 

 obviously borrowed from modern European science, is constructed on the follow- 

 ing principle. The framer of each system selected ad libitum as the epoch from 

 which the celestial motions were to be calculated, some very remote point of time, 

 with no other restriction than that, according to his notion of the length of a 

 year, the sun must have been then exactly in the vernal equinox ; and arbitrarily 

 assumed that, at that very instant, the moon and planets, with the nodes and 

 apsides of their orbits, were in conjunction with the sun (that is, that as seen 

 from the earth they were then in the imaginary right line passing through the 

 centres of the earth and sun). Such a coincidence most probably never occurred, 

 and certainly did not occur, as Mr. Bentley has clearly shown, at the commence- 

 ment of the Cali yuga of the system of Veraha, (in the year B. C. 3102), to 

 which instant of time it is ascribed, as well as to the epoch from which the system 

 is made to begin.* In this, as well as in the other purely Hindoo systems, the 

 number of revolutions performed by each celestial object during the Calpa, or 

 grand cycle, is fixed ; consequently the mean motion of each is determined ; and 

 the calculation of its mean heliocentric longitude at any assigned time is greatly 

 simplified by the above described assumption. For as the whole length of the 

 Calpa is to the part of it elapsed up to any assigned instant, so is the number of 

 revolutions performed by any planet in the former space of time to the number 

 performed by it in the latter space ; from which, deducting the integers, the 

 fractional remainder gives, according to the assumption in question, the sought 

 longitude. It is, however, certain that every such system being founded on a 



* To express myself more accurately, an actual conjunction is assumed to have taken place only 

 at the commencement of the great cycle (or Calpa') of this system ; and a mean conjunction at the 

 commencement of its Call yuga. What the actual positions of the heavenly bodies at the remoter 

 point of time were (supposing them to have been then in existence), it vpould be impossible now to 

 ascertain ; but their positions at the nearer epoch, calculated according to their mean motions, are 

 easily determined, and come out altogether different from what they should be, to verify the Hindoo 

 assumption respecting them. 



