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

90 ence of the earth pertaining to the locality. If d be this distance then the rule of three to be used is “ If the length of the rectified circumference viz. C rotates by the time the planet moves a distance δm, what is the arc traversed through by the planet if an arc ‘d’ of C rotates through ? ’’ The answer is (d × δm) / C which is the cor- rection required. Verses 4, 5, 6. The Correction Desāntara expressed in time. The eclipse of the Moon occurs at a place situated on the east of the primary meridian later than on the primary meridian and vice versa. The time in between the two moments is the Deśāntara expressed in time. The distance of Desāntara ie. the distance of the locality from the pri- mary meridian measured along a parallel to the terrestrial equator or Niraksha Rekhā is obtained by multiplying the rectified circumference by the Desāntara measured as above in ghatis and dividing by 60. Also the above time in ghatis multiplied by the planets’ daily motion and divided by 60, gives the correction in arc in the computed mean planetary motion. Further the week-day begins after or before the local Sun-rise by that Desāntara expressed in time according as the locality is on the east or west of the primary meridian. Also the week-day begins after or before the local Sunrise by the ghatis of the correction known as chara according as the Sun is in the northern or Southern hemisphere. Comm. An eclipse is first computed for the primary meridian. If an observer wants to know whether he lies east or west of the primary meridian and to know the Desāntara correction in time, the following procedure is to be adopted. Let a lunar eclipse begin x ghatis after the Sun-rise of the primary meridian. Let the observer note the time y ghatis which have elapsed after Sun-rise at his own place when the eclipse begins. Since a lunar eclipse