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

425
pertaining to the formula H sin δ = (H sin λ × H sin 24) / R ,
(4/R) H cos ZV = Para = the H sine of the declination of
that point whose longitude is equal to Vitribha-Sanku.
In other words Para is termed as the Vitribha-Sanku-
Rūpa-Krānti-Vṛttiya-Bhujajyājanita-Krāntijyā.
Now take E₁ E₂ = Para defined above. Draw circles
of equal radii with E₁ and E₂ as centres. Call (E₁) and
(E₂) as the Chandra-Kakshāmandala and Ravi-Kaksha
Mandala. Para by its formulation as (4/R) H cos ZV, is equal
to the maximum parallax in longitude for a given
H cos ZV ie. for a given position of V with respect to Z.
This being so, the parallax in longitude for an arbitrary
position of ☉ with respect to V will be
[Para × H sin (☉ - v)] / R according to the previous formu-
lation thereof. This form of the formula by its similarity
with the formula (a/R) H sin m, pertaining to the eccentric-
circle-theory, suggested to Bhāskara that the parallax in
longitude could be derived from the theory of the eccen-
trics or Prati-Vṛtta-Bhangi. In fig. 95, it will be noted
that E₁, E₂ are not the centre of the Earth and the position
of the observer on the surface of the Earth but such
points as E₁ E₂ is made equal to (4/R) H cos ZV or (a/d) H cos ZV
of the modern figure 4/R being equal to a/d, so that E₁ E₂
is of a variable magnitude varying with H cos ZV.
Comm. When H cos ZV = R ie. when V coincides
with Z, we have the maximum parallax. What then will
54