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

WESTERN COUNTRIES UNDER ISLAM 13 make the contents of Ptolemy's work accessible to the less learned. In the nineteenth century this book gave rise to a long controversy, which we shall presently consider somewhat in detail. Western Countries under Islam In the eleventh and twelfth centuries we do not find any names of conspicuous astronomers in Muhammedan Asia. But the western countries under Islam had in the meantime become ready to do their share of the work of keeping the mathematical sciences alive. In the Fatimite kingdom of Egypt Ali ben Abi Said Abderrahman ben Ahmed ben Junis, generally called Ibn Junis (died 1009), was distinguished both as an astronomer and a poet. At Cairo a liberally equipped observatory enabled him to verify the planetary theories which had once been developed in the neighbouring Alexandria, and in token of his gratitude to the reigning sovereign, Al Hakim, he named his work the Hakemite Tables.¹ We have to pass to the farthest west to find the next astronomer of mark in the person of Ibrahim Abu Ishak, known as Al Zarkali (in Europe afterwards called Arzachel). He was a native of Cordova, lived about 1029-1087, and edited planetary tables called the Toledo Tables.² In the following century we find two celebrated astronomers of Seville, Gabir ben Aflah, known as Geber (died 1145, often mistaken for the great alchemist, Gabir ben Haijan, in the eighth century),³ and Nur ed-din al Betrugi (Alpetragius), both of whom raised objections to the planetary theories of Ptolemy, though they failed to produce anything better of their own. Spanish astronomy continued to flourish for a while, although the power of the Arabs in the Peninsula was rapidly declining, and it produced in the thirteenth century a very remarkable man, who, although a Christian king, must be included in this account of Arabian astronomy,

1. Caussin has published an extract in vol. vii of the Notices et Extraits des manuscrits (Le livre de la grande table Hakemite). Other Chapters, trans- lated by the elder Sedillot but never published, are reviewed by Delambre, Hist. de l'astr. du Moyen Age, p. 95 sqq.
2. Never published. Delambre, l. c. p 176, and Steinschneider, Etudes sur Zarkali, Bullettino Boncompagni T. xx. p. 1. 3 The word algebra has also sometimes erroneously been connected with his name.