218 SPECIAL RESULTS IN THE UEANOLOGICAL 



The history of our knowledge of nebulae, if we regard 

 principally therein the number of discovered objects, their 

 thorough examination by the telescope, and an extensive 

 generalization of views, may, like that of double stars, be said 

 to begin with William Herschel. Until his time there were 

 in both hemispheres (including Messier's meritorious la- 

 bours), only 120 unresolved nebulae whose positions were 

 determined ; whilst as early as 1786, the great Astronomer of 

 Slough published his first catalogue containing 1000. 1 have 

 noticed in detail in the earlier part of this work that what were 

 called by Hipparchus and Geminus in the Catasterisms of 

 the Pseudo-Eratosthenes, and by Ptolemy in the Almagest, 

 "nebulous- stars/'' (ve^eXoei^e), are clusters of telescopic 

 stars, which, seen by the naked eye, have the appearance of 

 patches of nebulous light ( 361 ). The same appellation, under 

 the Latinised form of " Nebulosse," passed in the middle of the 

 33th century into the Alphonsine Tables ; probably through 

 the predominating influence of the Jewish Astronomer, Isaac 

 Aben Sid Hassan, chief of the wealthy synagogue at 

 Toledo. The Alphonsine Tables first appeared in print at 

 Venice in 1483. 



We find in an Arabian astronomer of the middle of the 

 tenth century, Abdurrahman Sufi, of Irak in Persia, the 

 first notice of what is now known to be a wonderful assem- 

 blage consisting of a countless host of true nebulae inter- 

 spersed with star clusters. The "White Ox" which 

 Abdurrahman saw shining with a milky brightness far down 

 below Canopus, was doubtless the larger Magellanic Cloud, 

 which has an apparent breadth of almost twelve diameters of 

 the moon, and covers a space of 42 square degrees in the 

 heavens; and which is first mentioned by European tra- 



