44 cosmos. 



The constant navigation of the Indian Ocean, washing the 

 shores of Eastern Africa, was the earliest means — especially 

 since the time of the Lagides and the Monsun-navigation — of 

 making mariners acquainted with the stars near the Southern 

 Pole. As early as the middle of the tenth century, we find, 

 as already observed, that the Arabs had given a name to the 

 larger of the Magellanic Clouds. This designation is, accord- 

 ing to Ideler's researches, identical with that of the White 

 Ox, el-bakar, of the celebrated astronomer Derwisch Abdur- 

 rahman Sufi of Rai, a city in the Persian province of Irak. 

 In his Introduction to the Knoivledge of the Starry Heav- 

 ens, which he composed at the court of the sultans of the dy- 

 nasty of the Buyides, he says that " below the feet of the Suhel 

 (by which he expressly means the Suhel of Ptolemy, Canopus, 

 although the Arabian astronomers named many other large 

 stars of Argo, el-sejina, Suhel) there is a ' white spot,' which 

 is invisible both in Irak (in the district of Bagdad and in 

 Nedsch, 'Nedjed') and in the more northern and mountain- 

 ous part of Arabia, but may be seen in the Southern Tehama, 

 between Mecca and the extremity of Yemen, along the coast 

 of the Red Sea."^ The relative position of the White Ox to 

 Canopus is here indicated with sufficient accuracy for the 

 naked eye ; for the Right Ascension of Canopus is 6h. 20m., 

 and the eastern margin of the larger Magellanic Clouds lies 

 in Right Ascension 6h. The visibility of the Nubecula ma- 

 jor in northern latitudes can not have been appreciably af- 

 fected by the precession of the equinoxes since the tenth cen- 

 tury, for the maximum distance from the north had already 

 been attained long before that period. If we follow the re- 

 cent determination of position for the larger cloud by Sir John 

 Herschel, we shall find that it was perfectly visible as far 

 north as 17° in the time of Abdurrahman Sufi ; at the pres- 

 ent time it is seen in about 18° north latitude. The south- 

 ern clouds must therefore have been visible throughout the 

 whole of southwestern Arabia, in Hadhramaut (noted for its 

 frankincense) as well as in Yemen, the ancient seat of civil- 

 ization of Saba, and the long-established colony of the Joctan- 

 ides. The southernmost extremity of Arabia, at Aden, on 



* Ideler, Untersuchwi gen uher den Ursprung vnd die Bcdeiitung der 

 Sternnamen, 1809, p. xlix., 262. The name Abdurrahman Sufi was 

 contracted by Ulugh Beg from Abdurrahman Ebn-Omar Ebn-Moham- 

 med Ebn-Sahl Abu'l-Hassan el-Sufi el-Razi. Ulugh Beg. who, like 

 Nassir-eddin, amended the Ptolemaic star-positions from his own ob- 

 servations (1437), admits that he borrowed from Abdurrahman Sufi's 

 work the positions of 27 southern stars, not visible at Samarcand. 



