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

Introduction xxix
set required, and the result obtained is what
Chandrasekhara has given us in the present work.
For easy reference, the sidereal periods as he
ascertained them, are given below side by side with
those of European astronomy, the Surya-Siddhanta
and the Siddhanta-Siromani. It is not my object to
criticise how far the constant employed in these two
Siddhantas were true when they were observed,
though it will be clear from the comparison that
they are certainly erroneous for the present time. It
is easy to follow when someone has led the way;
but it needed the art of a rural Pandit, guiltless of
western "fire" to prove their incorrectness and to
pave the way for further progress in this
department. (See table 1)
It will be seen from the above that Chandra-
sekhara has practically assumed the sidereal periods
of the Sun and the Moon, as given in the
Surya-Siddhanta, but has materially advanced upon
it as regards the periods of the other planets.
Having regard to the comparatively slow motion of
Jupiter and of Saturn, and the nature of the
instruments used, it would have been a surprise if
closer approximation to their true periods were
made.
Let us now compare the mean inclinations of
the orbits of the planets to the ecliptic.(See Table 2)
On account of the difference in the planetary
theories and in the method of calculation between
modern astronomy and our Siddhantas, the
eccentricities of the planetary orbits cannot be
compared with advantage. But as they made no
difference in the case of the Sun and the Moon,
their greatest equations are given here for
comparison. (See Table 3)