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

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But we have taken 13° as our latitude, so that tan ϕ = .2309.
Since s/12 = tan ϕ = .2309 ∴ s = 2.7708; let us take
this as 2.8″ so that the charas 10, 8, 3⅓ found for one inch
are to be multiplied by 2.8 to give the local charas. They
are in Vinādis, 28, 22.4, 9⅓ or in asus 168, 134·4, 56; for
convenience let us take 134.4 as 134, so that the charas
are 168, 134, 56. Thus the rising time of Sāyana Meṣa
at this locality is 1670 − 168 = 1502 asus i.e. 250 Vinādis
= 4-10 Nādis. Then let rS now represent 60°, instead of
subtracting EA from rA to get the combined rising time
of Meṣa and Vṛiṣabha, the Hindu practice is to subtract
the chara pertaining to Vṛiṣabha from the equatorial
rising of Vrishabha i.e. rE = 1793 − 134 = 1659 as got
before. Here it must be noted that EA° is the chara not
pertaining to Vṛiṣabha alone but to Meṣa and Vṛiṣabha
put together. That is why for ease, the chara to Meṣa,
the increase in chara for Vṛiṣabha, and the increase in
chara for Mithuna as well as their individual equatorial
rising times are given. The increments in the charas are
called chara-khandas just as the increments in the H sines
are called Jyā-khandas (khands means segments). Simil-
arly the rising time of Sāyana Mithuna is equal to 1937 −
56 = 1881 asus = 313.5 Vinadis = 5-14 Nadis. Now with
respect to Karkataka, its equatorial rising time is 1793,
for, from fig. 25, the equator at the equatorial place being
prime Vertical, if rM be Meṣa, its time of rising is given
by rE where E is the foot of the declination circle of M.
Similarly if MV represents Vṛiṣabha, when V comes to
the horizon, N the foot of the declination circle comes to
the horizon. Thus the rising time of any arc of the
ecliptic at an equatorial place is given by the correspond-
ing arc of the equator, which is intercepted between the
declination circles of the ends of the arc. So from fig. 26
if r ed ≃ be the equator, rED. ≃ the ecliptio, A the
Ayana or Summer solotice, P the pole rE, ED, DA etc.
the Sāyana Rasis Meṣa etc. a, b, c etc. the feet of the