(A. D. 1742 to 1761), and it is not clear whether the details given for earlier years represent what was actually observed or not.
11. The Arakanese follow the rules of Makaranta, in which fractions are reduced to their lowest terms, and very small remainders are neglected. Intercalary months are regulated by the Metonic cycle of 19 years, the use of which was propounded in the 10th book of Raja-Mathan, a Hindu astronomer.
12. The Makaranta is probably derived from the original Surya Siddhanta, because it defines the length of the year as 365 days, 15 nayi, 31 bizana 30 kaya (365 days, 6 hours, 12 minutes and 36 seconds), and because it uses mean reckoning. It is probable that the Burmese followed the same rules from Poppasaw's time down to 1100 B. E. (A. D. 1738).
13.The book which is now used in Burma is Thandeikta, the origin of which is involved in some obscurity. According to one account it was written about 1100 B. E., according to another about 1200. At any rate the change from Makaranta to Thandeikta reckoning was not effected all at once. From 1100 to 1200 the intercalary months are still regulated by the Metonic cycle, as in Arakan, but the intercalary days are not placed in the same years as in Arakan, and it is not clear by what rule they were fixed. During that century the growing discrepancy between the civil solar and luni-solar Years attracted attention. Much controversy ensued, the party of reform being led by a princess afterwards the chief Queen of King Mindon. The first departure from the rule of the Metonic cycle was made by putting an intercalary month in 1201 instead of in 1202, but the rules of Thandeikta do not appear to have been fully introduced untill 1215.
14. Thandeikta is based chiefly, if not entirely, on the present Surya Siddhanta, but applies its rules only to a limited extent. According to one account the present Surya Siddhanta was not known in Burma until one Bhavani Din, a learned pandit of Benares, brought it to Amarapura in 1148 B. E. (A. D. 1786), and about fifty years later it was translated into Burmese. Thandeikta does not adopt the system of apparent reckoning; mean years and mean months are still used. The practice of placing the intercalary month always next after Wazo and the intercalary day always at the end of Nayon, and only in a year which has an intercalary month, is still adhered to. But the new Surya Siddhanta was followed in small alterations of the length of the year and the month, and the Metonic cycle was abandoned, and intercalary months so fixed as to prevent further divergence between the solar and luni-solar years.
