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

lxii सिद्धान्त दर्पण
and his image, would enable him to find the
distance. He hastened home, but before he looked
into any work for the Sun's true diameter, he saw
his error. For, was he not assuming the thing he
wanted to find out? And his exultation was followed
by despair.
At ths stage the problem rested for several
years, till he became acquainted with rules for
calculating eclipses. He found that the parallax of
the Sun assumed in the Siddhantas was too large
to make predictions of eclipses correct. The anular
and total eclipses, together with those in which the
Moon just grazes the shadow, were his landmarks
in the determination of the problem. He was for
sometime in a sea of doubt. Perhaps the Siddhantas
were wrong in the mater of parallax, as in many
other matters. Perhaps his observations were not
made with that degree of accuracy which was
demanded by such problems.
These questions were never out of his mind a
single day through a long year. An accident
favoured him. He was reading the Atharvan
Upanishad, and was surprised to find that the Sun's
diameter was not 6500 yojanas as given in the
Surya-Siddhanta, but 72000 yojanas. This gave him
a fresh basis for calculation, and he was satisfied
that this diameter did not shift his landmarks to
any extent which he could detect. This gave 22" for
the Sun's horizontal parallax, and with careful
calculation that of the Moon was found to be 56'28".
Repeated observations left no doubt in his mind
about the correctness of his figures. Besides, here
was an authority from Sruti itself.¹ Taking 72000

1. Lastely he learnt that European astronomers find the