सिद्धान्तदर्पण (महामहोपाध्याय सामन्त चन्द्रशेखर सिंह - नग्न-नेत्र खगोल वेध एवं गणित महाकोश)

the modern Surya-Siddhanta Dr. Thibaut places the
period somewhere in the fifth century A.D. It is,
however, strange that he has omitted to discuss the
bearing of the Dhruvas of the seven stars he has
found in the old Surya-Siddhanta. Omitting Aslesha
which I cannot identify with certainty, the mean
general precession of the remaining six amounts to
about 24°. This implies, then, that astronomy as a
science began to be cultivated in India in the second
century A.D. at the latest.
We have already dwelt rather too long on the
determination of the starting point. But considering
the importance of the question in settling one of
the fundamental preliminaries to any possible
revision of on current almanacs, a word or two more
on the subject may be excused.
Chandrasekhara gives two methods for
determining the starting point. One is based upon
a verse of the modern Surya-Siddhanta, which he
takes to mean that the declination-circle passing
through the pole-star marks the junction between
Aries and Pisces (XII.61). He further cites his
authority for thus interpreting the verse from
Brahma-Jamala.
I am inclined to believe that he is mistaken in
thus interpreting the sloka of the Surya-Siddhanta,
though I have not seen Brahma-jamala, nor have I
an opportunity of doing so now. Taking, however,
the rule for granted it will be seen that the Dhruva
of the star was 21°-42' in Saka 1816. But from the
annual variation in the star's R.A. the change in its
Dhruva is nearly 3-3/4 minutes in a year. This fact
alone demolishes Chandrasekhar's view.
The other method suggested is an inverse