1880.] 



Dr. G. Thibaut^O« the Suryaprajnapti. 



181 



On the Suryaprajnapti. — By Du. G. TiirBATTT, Principal, Benares College. 



Part II. 



{Continued from p. 127.) 



Although ancient Indian astronomy was cliieflj interested in 

 the moon and although the greater part of the Surjaprajnapti treats 

 of her, especially of the places she occupies at different times in the 

 circle of the nakshatras, a detailed connected account of her motions 

 is not given anywhere, and we must combine the hints we meet with 

 here and there, in order to understand the theory by which the old tirthan- 

 karas tried to explain to themselves her motion. In doing this we are 

 of course greatly aided by the full and unambiguous account given of the 

 sun's motion, since it will not be presuming too much that the theory 

 which had been applied to the one luminary would be applied to the 

 other one also. As we have seen above, the sun's daily apparent motion is 

 regarded to be his true one and considered to take 2)lace round Mount 

 Meru ; his yearly motion is the consequence of his moving more slowly 

 than the stars ; his motion in declination is the result of his describing 

 round Mount Meru circles of varying diameter. All this is applied to the 

 moon too. The moon describes (or the two moons describe) circles round 

 Mount Meru at the height of eight hundred and eighty yojanas above the 

 earth, so that her place is eighty yojanas above that of the sun. She moves 

 slower than the stars and slower than the sun ; while the latter describes 

 during one yuga 1,830 (or strictly speaking 915) circles, the moon describes 

 only 1,768 (or again on the assumption of two moons 884) such circles ; 

 the difference of the two numbers = 62 indicates the number of times the 

 moon enters into conjunction with the sun. During the same period, viz., 

 the quinquennial yuga, the moon completes sixty-seven sidereal revolutions. 

 Each of these revolutions is, analogously to the sun's revolutions, divided 

 into two ayanas, an uttarayana and a dakshinayana, according as the moon 

 is proceeding towards the north or the south (of the equator as we should 

 add). In reality, it is true, the motion of the moon is much more compli- 

 cated, as it is not only oblique to the equator, like the ecliptic in which the 

 sun is moving, but also inclined to the ecliptic itself at an angle of about 

 5°, while moreover at the same time the points in which the inoon's path 

 cuts the ecliptic are continually receding. One of the consequences of the 

 revolution of the nodes did, as we shall see below, not escape the observation 

 of the author of the Suryaprajiiapti, but he was manifestly vinable to 

 account for it by a modification of his theory. According to him the moon, 

 like the sun, simply describes concentric circles round Mount Meru, sonie- 

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