सिद्धान्तशिरोमणि: गणिताध्याय (भास्कराचार्य - ग्रहगणित, मध्यमाधिकार व स्पष्टाधिकार सटीक)

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Verse 24. Conversion of liptas into what are called
Angulas.
H cos z of the eclipsed body at the moment of eclipse
being divided by the radius and the result being added to
2½ gives the number of liptas per angula. The time
elapsed after the rise of the body being divided by the
rising hour angle (both being expressed in the same units of
time) and the result being added to 2½ also gives the same.
Comm. While a parilekha or a geometrical drawing
of the eclipse is attempted at, the problem arises as to
how many liptas or minutes of arc giving the measure of
the disc are to be taken to be equivalent to one angula.
For example, suppose the diameter of the disc is 30'. With
what radius shall we draw the disc on a board or paper?
In this behalf, a convention based on observations is being
mentioned. The discs of the Sun and the Moon are
observed to be big at rise and small when they are on the
meridian. So, taking the measure of the disc to be 30'
for example, if the eclipse takes place at the rise of the
disc, it is laid down to draw the disc with a radius of 15/2½
ie. 6 angulas at the rate of 2½ liptas per angula. {The
word angula here mentioned might not be what we take
it to be today in our daily parlance as one inch. The
gnomon or S'anku was taken in those days to be of a
length equal to 12 angulas. Bhāskara mentions in the
beginning of Lilavati that 8 Yavas are together equal to
one Angula, twentyfour angulas to one hasta, four hastas
to one danda and 2000 dandas to one Kros'a, and 4 Kros'as
to one Yojana. Also a vamsa is equal to ten hastas. This
system discloses that, a Yojana equals 5 modern miles
according to Bhāskara's estimate of the diameter of the
Earth as compared with its modern estimate. (The method
given by Bhāskara as to how the diameter of the Earth
could be measured is found to be quite scientific as men-
tioned by us before).
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