NORTHERN LIMITS OF THE TROPICAL RAINS. 347 



routes in some of the more waterless tracts having" 

 to be entirely closed for traffic at some seasons: thus 

 the Egyptian Government at one time closed the ancient 

 caravan road across the Nubian Desert, from Korosko 

 to Abou Hammed, on account of the dreadful mortality 

 which took place upon it, but it was reopened upon 

 the application of foreign consuls, as the most direct 

 route to the Soudan. * 



In Northern Africa the Desert Zone may be held 

 to attain its greatest proportions, and the French traveller 

 Count D'Escayrac de Lauture, who had extensive 

 experience of desert travelling in the Sahara, and in 

 the region to the southwards known as the Soudan, 

 thinks that the regular tropical rains do not reach 

 higher than to about Lat. 17 N.,f while a later 

 authority, Mr. Keith Johnston, in the last issue of his 

 Royal Atlas, fixes the limit of these rains, at the parallel 

 of Lat. 1 8 N. An examination of the map will 

 show that this line passes as nearly as possible through 

 the important town of Berber, on the Nile, and slightly 

 to the southwards of the western limit of the great 

 bend of that river, near Korti, now celebrated as having 

 been the British store depot and point of departure 

 for the force which marched across the Bayuda Desert, 

 for the relief of General Gordon, at Khartoum, in 1885. 

 The objects of that expedition, as we may all remember, 

 were frustrated, not through any fault committed by 

 the distinguished general who commanded it, but through 

 the fatal influence of civil politicians at ,home, who 



* See The Xile Tributaries of Abyssinia, by Sir Samuel Baker, 1867, p. 15. 



f Le Desert et Le Soudan, Etudes sur L'Afrique au Nord de 1'Equateur, 

 par M. Le Comte D'Escayrac de Lauture, Paris 1853, p. 60. 



See Keith Johnston's Royal Atlas, published 1884, Map No. 42. 

 (Egypt and Nubia.) 



