ब्राह्मस्फुटसिद्धान्त (ब्रह्मगुप्त - शून्य, कुट्टक, बीजगणित एवं सम्पूर्ण २१ अध्याय सान्वय सटीक)

14 ASTRONOMY IN ANCIENT NATIONS as he owed all he knew about the science to the example and the teaching of Muhammedans and Jews. King Alfonso X, of Castille named el Sabio (1252-1284), followed the example of the Caliphs and called astronomers to his court to assist in the preparation of the renowned Alfonsine Tables. With Alfonso the study of astronomy disappeared from Spain, but not before it had been revived in the East. In 1258 the still existing but shadowy Caliphate of Baghdad was swept away by the Mongol conqueror Hulagu Khan, grandson of Genghis Khan; but already in the following year this great warrior liste- ned to the advice of his new vazier, Nasir ed-din al Tusi (born at Tūs in Khorasan in 1201, died in 1274), and founded a great and magnificient observatory at Merāgha, in the north-west of Persia, In this observatory, which was furnished with a large number of instruments, partly of novel construction, Nasir ed-din and his assistants observed the planets diligently and produced after twelve years labour, the " Ilokhanic Tables," Among the astronomers of Merāgha seems to have been Juhanna Abu 'l Faraj, called Bar Hebrāyā, or the son of a Jew. He was a Christian, born in 1226 and from 1264, till his death in 1286 Maphrian or Primate of the Eastern Jacobites. He left a well- known chronicle and an astronomical work, both written in Syriac, as well as other writings.¹ The observatory at Merāgha had not a long life, and Asiatic astronomy had to wait a century and a half, until the grandson of another terrible conqueror erected another observatory. Ulug Begh, grandson of Tamerlan, drew learned men to Samarkand and built an observatory there about the year 1420, where new planetary tables and a new star catalogue, the first since Ptolemy's, were prepared. Ulug Begh died in 1449, he was the last great Asiatic protector of astro- nomy; but just as the Eastern countries saw the star of Urania setting, it was rising again for Europe. In this review of Arabian astronomers we have only men- tioned a few, omitting several names of distinction, whose ¹ Le livre de l' ascension de l' esprit sur la forme du ciel et de la terre. Cours d' Astronomie redige en 1279 par Gregoire Aboulfarag, dit Bar Hebraeus. Publie par F. Nau, Paris, 1899-1900 (2 parts, Syriac and French). His chronicle is the chief authority for the fable about the burning of the Alexandrian Library by order of the Caliph Omar. For a very thorough refutation of this see Butler, The Arab Conquest of Egypt. Oxford, 1902 pp 401-426.