The Aryasta^ata contains all the leading features of a system the difference of which from the commonly received opinions was known to us from the accounts given of it by many of the Hindu astronomers. Aryabhata's curious system of arithmetical notation is taught in the Da^agïti, his theory of the earth revolving on its axis in the Siddhanta, and now that we know his date, we know at the same time that a Hindu astronomer had the boldness, as Whitney puts it, to withhold his assent from the commonly received theory. Another remarkable feature of the book is that the lunar mansions or naksatras are not taken notice of. The only word which reminds us of their existence is A$vayuja, not referring to the naksatra, but taken as the name of the first year in the revolution of Jupiter, whence further it may be deduced that Agvinï was the first in the order of the lunar mansions at the time the work was composed.
As yet only the two forenamed works of Aryabhata have been recovered, but we may reasonably hope that others will turn up in time. Albïrüni (Mém. sur 1'Inde, p. 371) quotes a whole passage from Aryabhata «le Cousoumapourien», which must have made part of a book different from the Dagagïti and the Aryastagata, it not being found in those two. It has been surmised by Fitz Edward Hall that there must have been two astronomers of the name of Aryabhata, a surmise which want of materials only prevented him from raising to a certainty. By my possessing a copy of an Aryabhatakrta-Mahasiddhanta or Aryabhatakhyo Mahasiddhanta, I am in a position positively to prove the correctness of Hall's shrewd guess. The Mahasiddhanta is an astronomical work in 18 Chapters, and more than 600 verses in Arya and Upagïti in irregular succession. The verses are altogether lame and pithless. The author distinctly states that he has written his work mainly on the principles of the «old» Aryabhata, and the truth of his assertion is born out, partly at least, by his employing the great Aryabhata's peculiar system of arithmetical notation. He informs us further that he had introduced corrections of his own; the necessity of applying such corrections to theold Aryabhata's works being one of the reasons that he, the younger, wrote his book. Another reason, so he adds, was the scarcity of those works. Let us hear himself.
Evam paropakrtaye svoktyoktam khecaranayanam |
Kimcit pürvagamasamasamam 1 uktam viprah pathantv idam nanye || «Thus I have given for the benefit of others, the calculation of the planets on my own authority, it being a little different(?) from ancient authorities. Brahmans, no others, should study it.»
1 There is something wrong in samasama; I cannot make a verse out of it, for agamasaroam uktam will not do,