92 LITERATURE OF THE ARABS. 



the introduction of observatories. Appended to the 

 celebrated mosque at Seville was the lofty tower of 

 the Giraldo, built under the superintendence of the 

 famous mathematician Geber (A. D. 1196), which 

 long served this purpose, and which still remains 

 one of the most noble and ancient monuments, per- 

 haps, in Christendom, in honour of this science. 

 The learned Bailly attributes the revival of astron- 

 omy to the Spanish Arabs, and the translations of 

 the works of Alfragani. He affirms that Kepler 

 drew the ideas that led to his discovery of the ellip- 

 tical orbits of planets from Nureddin Petrucci, whose 

 Treatise on the Sphere is preserved in the Escurial. 

 From Lalande and Andres we learn that Alfonso X., 

 king of Castile, who has immortalized himself by 

 his astronomical pursuits, and whose tables have 

 contributed so much to promote the knowledge of 

 the heavenly bodies, received his information chiefly 

 from the Moors, whom his liberality induced to 

 settle at Toledo. 



The schools of Bagdad and Cordova did not neg- 

 lect the study of optics. Alfarabi, Ibn Haitim, and 

 Alhazen devoted their attention to this subject ; but 

 the works of the two former are lost. The treatise 

 of the latter, who wrote in the twelfth century, has 

 been frequently noticed. It is cited by our distin- 

 guished countryman Roger Bacon ; and was illus- 

 trated by Vitellio, a native of Poland, who lived in 

 the thirteenth century. In mathematics, though 

 the Saracens did not ascend to the higher branches, 

 yet in the other division of the science their know- 

 ledge was far from being inconsiderable. The 

 works of the most eminent Greek geometricians 

 were translated, and the schools of the East sup- 

 plied in their vernacular tongue with versions of 

 Euclid, Theodosius, Hypsicles, Menelaus, and Apol- 

 lonius of Perga. 



How highly these studies were valued by Alma- 

 moim, may be imagined from his liberal offer of 100 



