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

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the necessity for knowing the value of CN at any subse-
quent moment arises. β, of course, could be computed,
knowing the hourly variation of β, which in its turn could
be known, by a knowledge of the hourly variation in λ, the
longitude of the Sapātachandra.
The magnitude of CN is calculated by the rule of
three "If by the Sparsa-Sthiti-Khanda we have initially
the initial value of CN, what shall we have for (T –t) ?"
The result is [(T–t) × CN] / T where CN is the initial value
of CN and T the Sparsa-Sthiti-Khanda. Substituting the
values of CN and T from verse 12, where
CN = √((R+r)²–β²) and T = [√((R+r)²–β²) × 60] / (m₁–s₁)
we have the required Bhuja as
[(T–t) (√(R+r)²–β²)] / [60 (√(R+r)²–β²)] × (m₁–s₁) = [(T–t) {m₁–s₁}] / 60 minutes
= (T–t) (m₁–s₁) degrees as given.
Similarly we could find the Bhuja with respect to
'totality' ie. the 'Marda-Bhuja' as it is called.
Note. One might mistake M₁ M₂ of fig. 74 (M₁ per-
taining to a subsequent moment) to be the Bhuja defined
above, which is the join of the centre of the eclipsing body
and the foot of the latitude at the middle of the eclipse.
That is why Bhāskara uses the word 'Madhya-Sarāgra-
Chihna' in the commentary, meaning thereby not the
foot of the actual latitude at the middle of the eclipse but
only the point N of fig. 77 which 'signifies' it.
Second half of verse 16 and first half of verse 17.
Taking the latitude of the Moon at a given time as
Koti, and Bhuja as the Bhuja of the moment defined
above, we have the Karṇa of the moment as √(Bhuja² + β²);
R+r–Karṇa gives the Grāsa at the moment.