54 LONGITUDE-CORRECTION = Thus the calculated time of moonrise T₂-T₁ ghatis. At the local place, the time of sunrise on that day will be (T₁-λ/6) ghatis; (1) and the time of moonrise will be (T₂/6) ghatis-(the time of rising at the local place of a portion of the ecliptic equal to > (Moon's daily motion in minutes - Sun's daily motion in minutes) 360 minutes of arc.) Therefore at the time of moonrise the time indicated by the water- clock will be. (T₂-T₁) ghatis- (the time of rising at the local place of a portion of the ecliptic equal to > (Moon's daily motion in minutes-Sun's daily motion in minutes) 360 minutes of arc). The difference between (1) and (2) gives the time of rising at the local place of a portion of the ecliptic equal to λ (Moon's daily motion in minutes - Sun's daily motion in minutes) 360 minutes of arc, which is evidently the time of rising at the local place of a portion of the ecliptic equal to the motion-difference of the Sun and Hence the Moon corresponding to the longitude of the local place. rule. To obtain the local longitude in ghatis we should multiply the above difference of (1) and (2) by 60 and divide the product (thus obtained) by the time in which an arc of the ecliptic equal to the difference between the daily motions of the Sun and Moon rises above the local horizon.¹ Criteria for knowing whether the local place is to the east or to the west of the prime meridian: 9. When the rising of a planet is observed before the comup- ted time or the first contact of an eclipse is observed after the 1 See Govinda Svāmi's commentary and the Siddhanta-dipikā.
