52 and the true longitude of the Sun calculated (from the ahargana) for the middle of the day (without the application of the longitude-correction) give the longitude (correction for the Sun). This also is not so, because for people who live on the same parallel of latitude, the latitude (and therefore the shadow of the gnomon) is the same.¹ This rule has also been criticised by Sripati, who says: LONGITUDE-CORRECTION "Whatever is obtained here as the difference between the longitude of the Sun obtained from the midday shadow and that obtained by calculation (for midday, without the application of the longitude-correction) when multiplied by the (local) circumference of the Earth and divided by the (Sun's daily) motion gives the yojanas of the longitude (i.e., the distance in yojanas of the local place from the prime meridian). This is gross on account of the small change in the Sun's declination.". A rule for finding the longitude in time : 7. Those who have studied the astronomical tantra com- posed by (Arya)bhata and are well versed in Spherics state that the difference between the time of an eclipse calculated by the usual method from the longitudes of the Sun and the Moon (both) uncorrected for the longitude-correction and the time of the eclipse determined by observation is the more accurate value of the (longitude in) time.* "Choice is made, of course, of a lunar eclipse, and not of a solar, for the purpose of the determination of longitude, because its phenomena, being unaffected by parallax, are seen everywhere at the same instant of absolute time; and the moments of the total disappearance and first reappearance of the moon in a total eclipse are further selected, because 1 See also LBh, i. 28. The local circumference of the Earth is the circumference of the local circle of latitude. ³ Si Se, ii. 103. 4 Similar rules occur also in LBh, i. 29; Sise, ii. 106(i); TS, i, 31(ii)-32(i).
