72 Account of the Founding of a 



long series of years. It was in the portico of the Museum, 

 which was placed close to the palace of the king, in the Bni- 

 chion, that Eratosthenes fixed his armillary spheres, by which 

 to follow the motions of the stars. A hundred years later, the 

 same apparatus was employed by Hipparchus, the greatest as- 

 tronomer of antiquity ; and by Ptolemy, 150 years after the 

 Christian era. Hipparchus had fixed in the same place his ce- 

 lestial sphere, which exhibited a representation of the stars, ar- 

 ranged according to the discoveries which he had made. Here, 

 too, was found the Alidade of this same philosopher, as also 

 the Astrolabe of Ptolemy, and his parallel rulers. After a flou- 

 rishing existence of 400 years, in which the basis of practical as- 

 tronomy was established, the Observatory of Alexandria began 

 to decline, and it is probable it was entirely destroyed at the 

 time that the Arabian conquest overthrew all the scientific esta- 

 blishments of that country. 



If the period which succeeded, of nearly a thousand years du- 

 ration, until the revival of letters, was truly a dark age for the 

 most of the sciences, this is, at the same time, less true of as- 

 tronomy than of any other. The Arabian caliphs and the Mon- 

 gul khans vied with each other in their application to the study of 

 this science, and in endeavouring to promote it by the esta- 

 blishment of observatories. The caliph Almamoura founded 

 one observatory at Damas and another at Bagdad ; and, at a 

 later period, there was another established at Bagdad by the 

 Egyptian caliph Hakem. At the overthrow of the caliphat, in 

 the thirteenth century, astronomy found protection with the vic- 

 torious Monguls. Holagu-Ilekan, the grandson of Gengiskan, 

 the conqueror of Mostazem, the last of the Abassides, was a zea- 

 lous patron of this science. Nassireddin de Thous, the greatest 

 astronomer of his time, then flourished in the East. He had 

 been banished the court of the caliph Mostazem by a low cabal. 

 The brother of Holagu, and his predecessor in the khanate, 

 Mangu by name, had previously declared his intention of found- 

 ing an observatory, and had instructed his brother Holagu, who 

 acted as his general against the caliphate, to send him the illus- 

 trious astronomer, as soon as he had made himself master of 

 Irak. iNIangu did not survive to sec the accomplishment of 

 this event ; but as soon as Holagu had terminated his campaigns, 



