LONGITUDE-CORRECTION AND ITS APPLICATION 55 computed time, the observer is to the east of the prime meri- dian. In the contrary case, he is to the west (of the prime meridian). 2 The longitude correction and its application: 10(i). Multiply the (mean) daily motion of a planet the Sun, or the Moon's ascending node by the longitude in ghatis and divide by 60. Apply the resulting correction to the (corres- ponding) mean longitude of the planet, the Sun, or the Moon's ascending node (calculated for mean sunrise at Lankā) posi- tively or negatively according as the local place is to the west or east of the prime meridian. (Thus is obtained the mean longi- tude of the planet, the Sun, or the Moon's ascending node for mean sunrise at the svaniraksa place³).4 Rule for finding the length of the local circle of latitude and the distance of the local place from the prime meridian: 10(ii). Multiply the number of (yojanas in) the Earth's circumference by the Rsine of the colatitude and divide by the radius; (the result is the number of yojanas in the local circle of latitude). Multiply that by the longitude in ghatis and divide by 60; the result (thus obtained) is stated to be the (distance in) yojanas (of the local place from the prime meridian).5 ¹ The computed time corresponds to the place lying at the intersection of the local circle of latitude and the prime meridian. 2 Cf. LBh, i. 29; SuSi, i. 63; Sise, ii. 105(i)-106(i). 3 The svanirakṣa place is the place where the local meridian intersects the equator.
- This rule occurs also in LBh, i. 31 and Sise, ii. 106(ii).
5 Cf. SūSi, i, 60(i), 64(ii)-65,
