248 SPECIAL RESULTS IN THE UEANOLOGICAL 



the nubecula major in northern latitudes cannot have been 

 materially altered since the tenth century by the precession 

 of the equinoxes, for in the course of the next ten centuries 

 it reached its maximum distance from the north. Taking 

 the most recent determination of the place of the larger 

 cloud by Sir John Herschel, we find that in the time of Ab- 

 durrahman Sufi it was perfectly visible as far north as 17 

 N. Lat. ; at present it is so nearly to 18. The nubeculae 

 might therefore have been seen throughout the whole of the 

 south-west of Arabia, the incense-producing country of Had- 

 hramaut, as well as in Yemen, the ancient seat of civilization of 

 Saba and of the early immigration of the Joctanides. The 

 extreme southern point of Arabia, at Aden on the Straits of 

 Bab-el-Mandeb, is in 12 45', and Loheia is only in 15 44/ 

 North Lat. The rise of many Arab settlements on the inter- 

 tropical east coast of Africa, both north and south of the 

 equator, also naturally led to a more complete and detailed 

 acquaintance with the southern constellations. 



Of civilised navigators, the first who visited the West Coast 

 of Africa beyond the Line were Europeans, and first, and more 

 especially, Catalonians and Portuguese. Undoubted docu- 

 ments, i. e. the Map of the World of Marino Sanuto Torsello, 

 of the year 1306; the Genoese "PortulanoMediceo"of 1351; 

 the "Planisferio de la Palatina," 1417; and the "Mappa- 

 mondo" of Fra. Mauro Camaldolese, between 1457 and 

 1459, shew that 178 years before the reputed first discovery 

 of the Cabo Tormentoso (the Cape of Good Hope) by Bar- 

 tholomew Dias, in the month of May 1487, the triangular 

 configuration of the southern extremity of the African con- 

 tinent was already known ( 44 ) . After Gama's expedition, 

 the rapidly increasing importance of the commercial route 



