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

Introduction lxi
Chandrasekhara is in the Sun's parallax. The history
of his attempts at determining it is no less
interesting than the results he actually obtained.
The ancient astronomers of India were satisfied with
taking for the parallax of each planet, 1/5th part of
its mean daily motion. Accordingly, the Sun's
horizontal parallax was considered to be 3'56", and
that of the Moon 52' 42". With rough instruments
at their disposal, the ancient observers could not
but assign wrong values. But awkwardly enough,
the parallaxes of the Sun and Moon come into every
prediction of their eclipses. So while modern
astronomy increases the distance of the Sun to
something like 400 times the distance of the Moon,
our ancient astronomers placed him no farther than
14 times this distance. Chandrasekhara has removed
him to a distance of about 154 times the mean
distance of the Moon.
Chandrasekhara told me that before he got the
parallax, he had passed many an unhappy day. He
was then very young, but was anxious to know the
Sun's distance. He could not even imagined how
the distance could ever be known. The ancient
works were dogmatic in their assertions, and did
not say a word about the method employed. By his
failure in approaching the problem, he became
disheartened. One day thus dejected in mind, while
he was coming home, he noticed an image of the
Sun projected through a narrow aperture in a fence
of palm leaves close to his house. This phenomenon
well known to every tyro in physical science made
him reflect, and he thought that he had got a
solution of his problem. Could he but get the Sun's
real diameter. This similar triangles on the two sides
of the aperture, with their bases formed by the Sun