I 

 *$ 61, 62] The Spanish School : Nassir Eddin 6 A 



the same school are due some improvements in instru- 

 ments and in methods of calculation, and several writings 

 were published in criticism of Ptolemy, without, however, 

 suggesting any improvements on his ideas. 



Gradually, however, the Spanish Christians began to drive 

 back their Mahometan neighbours. Cordova and Seville 

 were captured in 1236 and 1248 respectively, and with their 

 fall Arab astronomy disappeared from history. 



62. Before we pass on to consider the progress of 

 astronomy in Europe, two more astronomical schools of 

 the East deserve mention, both of which illustrate an 

 extraordinarily rapid growth of scientific interests among 

 barbarous peoples. Hulagu Khan, a grandson of the 

 Mongol conqueror Genghis Khan, captured Bagdad in 1258 

 and ended the rule of the Caliphs there. Some years 

 before this he had received into favour, partly as a political 

 adviser, the astronomer Nassir Eddin (born in 1201 at Tus 

 in Khorassan), and subsequently provided funds for the 

 establishment of a magnificent observatory at Meraga, near 

 the north-west frontier of modern Persia. Here a number 

 of astronomers worked under the general superintendence 

 of Nassir Eddin. The instruments they used were remark- 

 able for their size and careful construction, and were 

 probably better than any used in Europe in the time of 

 Coppernicws, being surpassed first by those of Tycho Brahe 

 (chapter v.). 



Nassir Eddin and his assistants translated or commented 

 on nearly all the more important available Greek writings 

 on astronomy and allied subjects, including Euclid's 

 Elements, several books by Archimedes, and the Almagest. 

 Nassir Eddin also wrote an abstract of astronomy, marked 

 by some little originality, and a treatise on geometry. He 

 does not appear to have accepted the authority of Ptolemy 

 without question, and objected in particular to the use 

 of the equant (chapter IL, 51), which he replaced by 

 a new combination of spheres. Many of these treatises 

 had for a long time a great reputation in the East, and 

 became in their turn the subject-matter of commentary. 



But the great work of the Meraga astronomers, which 

 occupied them 12 years, was the issue of a revised set of 

 astronomical tables, based on the Hakemite Tables of Ibn 



6 



