12 , MEAN LONGITUDES OF THE PLANETS [CH. I (according as the local place is to the east or to the west of the prime meridian). Application of the longitude correction to the mean longitude of a planet for mean sunrise at Lanka gives the longitude of the planet for mean sunrise at the place where the local meridian intersects the equator. The place where the local meridian intersects the equator is called svaniraksa (i.e., "local equatorial place"), Justification of the longitude correction : 34. The method of adding or subtracting motion corres- ponding to the longitude (of the local place) in ghatis (taught above) is the cause of the decreased or increased tithi 1 (i.e., the local time of observation of the eclipse); seeing is unaffected by that correction. • Sankaranarayarta comments on this verse as follows : "The rule which has been stated here in accordance with which the correction obtained from the longitude, in ghatis or yojanas, is to be subtracted from or added to the mean longitude of (the Sun and) the Moon according to the direction of the local place (east or west of the prime meridian) is the cause of the decrease or increase of the tithi (i.e., of the local time of observation of an eclipse). Therefore the previous remark that by those who are situated to the east of the prime meridian an eclipse is seen after the time calculated for its occu- rence (on the meridian of Lanka), and by those who are situated to the west of the prime meridian it is seen in advance (of the calculated time) remains unaffected. How ? For the time of occurrence of an eclipse as obtained by subtracting the longitude of the Sun from that of the Moon without making allowance for the longitude correction is certainly less or greater than the local time which is obtained by properly subtracting or adding the longitude correction. Therefore at new moon or full moon an eclipse is naturally seen on the two sides (of the prime meridian) after or before the time calculated for its occurrence (on the meridian of Lanka), Otherwise (i.e., if the longi- tude-correction be not made), the difference between the times of observation of an eclipse by those situated to the east and to the west (of the prime meridian) would not be explained." Paramesvara observes : "That is the reason for the calcula ted time (of occurrence of an eclipse on the meridian of Lanka) being less or greater than 1 See Glossary.
