Page:Sewell Indian chronography.pdf/111
199, the English year being a leap-year = July 17th. 2 = Monday. At mean sunrise that day (Jacobi calculates it as 5115). The moment of full-moon (5000) was 116 (=, by Table X., 1 h. 8 m.) 8 h. 13 m. before mean sunrise on Monday, or at 15 h. 47 m. Laṅkā time on 7 h. 5 m. Sunday, July 16th, A.D. 1144.
Professor Jacobi remarks that "it is likely there was a small lunar eclipse," and refers readers to von Oppolzer's Canon der Finsternisse. My own small volume, "Eclipses of the Moon in India,"[1] now contains all the information required, as it gives von Oppolzer's own figures converted to Indian, Laṅkā, time. Table E of that work shows that on Sunday, July 16th, A.D. 1144, there was an eclipse of the moon measuring 2.5 (in twelfths), and that von Oppolzer's determination of the moment of greatest phase, stated in Laṅkā time, is precisely the very moment determined by our own work above, viz., 15 h. 47 m. after mean sunrise. Continuing the calculation for absolute accuracy I find that the Hindū system fixes 15 h. 51 m., or 4 minutes later, as the moment of greatest phase.
This exact correspondence between Hindu computation and modern European science, while it is interesting, is not always to be looked for; though in lunar calculations we need never expect serious divergence, and it must not be forgotten that the time of occurrence of eclipses would generally be computed locally, i.e., taking count of the difference in latitude and longitude between Laṅkā and the principal place in the neighbourhood of the calculator.
Example 23.—To find whether a true tithi is repeated (adhika) or suppressed (kshaya).
Rule. Find, by the method shown in the last example, the tithi-index () at sunrise of the civil day concerned, and the beginning and ending times of the tithi then current. If the current tithi, which began before sunrise of that day, is also current at the next sunrise, so that the sun rose twice on it, it is added or repeated (adhika). If the tithi current at sunrise ended very shortly after sunrise, and the next tithi, beginning after sunrise and ending before the next sunrise, was therefore current at no sunrise, the latter tithi is expunged (or becomes kshaya). Sunrise was probably, for local almanacs, calculated as true or apparent sunrise, but for purposes of our general Tables is taken as mean sunrise. The "repetition" or "expunction" of a tithi does not concern the duration of the tithi itself, which always runs its course; but merely concerns the nomenclature of the civil day which takes its name from the tithi current at sunrise. (Text, "Adhika and kshaya tithis," §§ 86-89, "Hints," Nos. 15, 16.)
As an example we examine the adhika tithi noted in the Pañchāṅg extract on pp. 14, 15 of the Indian Calendar. We examine, that is, the tithis connected with the sunrises on the 11th, 12th and 13th September, A.D. 1894 (New Style), corresponding to the 12th, first 13th, and second 13th tithi of the bright or first fortnight of amānta Bhādrapada in Śaka 1817 current. The days concerned were Tuesday, Wednesday and Thursday. We accept the Pañchāṅg as accurate. The times are given in ghaṭikās and palas, and we convert them to hours and minutes by Table XXV. The 12th śukla tithi ended on the Tuesday at 56 gh. 44 p., or at 22 h. 42 m. after sunrise. The 13th tithi, that is, began at that moment, or at 1 h. 18 m. before sunrise on the Wednesday. It ended at 1 gh. 23 p., or 33 m. after sunrise on Thursday. It was therefore current on the two sunrises of Wednesday and Thursday. It had to give its number to both Wednesday and Thursday. Wednesday was connected with the "first 13th" śukla tithi and Thursday was connected with the second tithi of the same number, or the "second 13th." The first is generally called the "adhika 13th" and the second the "nija 13th." The 14th tithi was current at sunrise on the Friday, ending 5 gh. 18 p., or 2 h. 7 m. later, and it gave its number to that Friday.
- ↑ Published ten years later.