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

xxxii . सिद्धान्त दर्पण
It will be needless to compare the rates of
motion of the nodes and apsides. It is possible for
modern European astronomy, with instruments
enabling it with ease to measure the three thousand
and six hundredth part of a degree and with its
engines of higher methematics to handle intricate
problems, unheard of before, to deduce the
elements of orbits from a very few observations
made at no distant dates. But it requires the lapse
of years - nay centuries - to do the same with
primitive instruments and equally primitive
mathematics. The motions of the nodes and apsides
are so slow that Bhaskara despaired of ever
measuring them. Chandrashekhara was equally in
despair in these cases. But as the positions of the
Moon's nodes and perigee are often required, and
their motions comparatively rapid, I quote their
side-real period in mean solar days.
              Eng. Ast.   Surya S.   Siromani   Darpana
Node      6798.279   6794.395   6792.254   6792.644
Perigee   3232.575   3232.094   3232.734   3232.657
The reader will notice that Chandrasekhara has
devised a correction to be applied to the
Mandochcha of the planets, Mercury, Mars and
Saturn. He has called it Parochcha and the greatest
amounts are 11' 20', 7° 30' and 5° for the three
planets respectively (Siddhanta Darpan V.76).
It is, however, in computing the Moon's place
that Chandrasekhara has discovered some original
correction, - original in the sense of their having
been unknown to the ancient astronomers of our
country. It is curious to note that they failed to
discover the perturbation, known as Evection which
is said to have been detected by Hipparchus about