1917.] The Fourth Indian Science Congress. clxv 



the above limits, and contains the system which has been followed e\ it 

 since down to the present day. 



The system preserves some characteristic Indian features. The 

 period of the revolutions of the heavenly bodies is not defined by num- 

 bers of days but is fixed with reference to the Mah&yuga or cycle of 

 4,320,000 years. The number of revolutions completed in this period 

 fixes the duration of each revolution. The sun, the moon, Mars, Jupiter 

 and Saturn are dealt with in this fashion. For Mercury and Venus the 

 procedure and its explanation are different. Their mean positions (thi 

 in agreement with the system of the Greeks) are given as the mean posi- 

 tions of the sun ; their actual positions, now to the East and now to the 

 West of the sun are explained as due to the action of unseen beings 

 designated ** forms of time " which pass through the zodiac and continually 

 draw the planets to them by cords of air. These disturbing beings mak 

 the same number of circuits in a yuga as Mercury and Venus. 



In this system the use of the mahdyuga and the still greater kalpa . 

 which are out of all proportion to the periods required in astronomical 

 observation, shows the strong influence of religion on the scientific method- 

 of India. So dominant was this influence that one of the Siddhantas was 

 excluded from the Smriti simply because it made no use of these period 

 which enjoyed a religious sanction. This method of periods was essen- 

 tially unscientific. Instead of measuring the periods as multiples of th< 

 year, the year became a submultiple of a particular period and the accu- 

 racy of the determination of these smaller periods was sacrificed in the 

 interests of the mahdyuga into which a definite number of them must be 

 fitted. 



The mythological device employed to explain the libration of the 

 nodes of the moon and the apparent inequality in the motions of certain 

 planets is another illustration of the same characteristic. 



The question as to the dependence of this system on the teaching.- 

 of the Greek astronomers is one of long standing. It is natural that 

 India' should desire to establish its independence of foreign influence in 

 the development of its astronomical system. The weight of evidence seem 

 to be, however, in favour of the conclusion that the essential features 

 of the new svstem owe their origin to that contact with Greece which 

 established itself in commerce in the early centuries of our era. The new 

 and scientifically constructed system which is found m the Surya bid- 

 dhanta and which has remained practically unmodified ever since, is so 

 identical with that of Ptolemy's Syntaxis that it is difficult to imagine 

 that the two systems had an independent origin. Setting aside peculiari- 

 ties in the mode of explaining certain phenomena, features that are 

 characteristically Indian, there remains an identity of astronomical 

 method so complete that anyone following the rules of the Indian bicl- 

 dhanta is bound to arrive at practically the same results as he would 

 have reached by employing the formulae of the Ptolemaic astronomy 

 It is no argument against; the identity of the origin of the two systems t, 

 point to differences in some of the determinations given in each. This 

 discrepancy in some minor details is easily intelligible and cannot set 

 aside a conclusion based on complete and minute agreement m regard to 

 fundamental conceptions. It is true that Aryabhatta whose date -cannot 

 be fixed earlier than the third century nor later than the fifth, asserts the 

 doctrine of the rotation of the earth on its own axis as a sufficient expla- 

 nation of the apparent movements of the heavenly bodies- One can 

 imagine such a single conception arising independently in different minds 

 and it is found also among the predecessors of Ptolemy among the 

 Greeks ; but in Greece as in India this fruitful conception fell on unre- 

 ceptive soil. It was first controverted and then ignored. Only attei 

 the lapse of centuries did it succeed in gaining in the ^ of "onnon- 

 opposition, the place which it now permanently holds. It i not, how- 

 ever, possible toaccept such mutual independence in the ca*o of Mom* 

 plete elaborate systems both resting on the peculiar theory of opicyclic 



