58 JOURNAL, BO MB A Y NA TURAL HISTOR Y SOCIETY, Vol. XV 111. 



The annual rainfall at Aden rarely exceeds 6 or 7 inches, while 

 occasionally there falls no rain for a year and a half. The subjoined 

 readings give the registered rainfall in the Crater since 1871; previous 

 to that year the maximum recorded in the preceding eleven years was 

 8"03 inches in 1870, while in 1871 the fall amounted to 24 cents only. 1 

 Rainfall registered at the Civil Hospital in the Crater. 



Mouths. 



1872-73. 



3873-7-1. 



1874-75. 



1875-76. 



April 



May 



June 



July 



Augu8t 



September 



October 



November 



December 



January 



Februaiy 



March 



Total 



Inches. 

 1 

 

 

 

 

 

 

 

 

 

 

 4 



Cents. 

 

 

 

 

 58 

 



Inches. 

 

 

 

 

 

 



Cents. 

 o 



2 

 

 

 

 

 

 22 

 18 



17 

 65 



73 



As the hills on the western side of the Crater are precipitous, the 

 rain-water descending from them is carried rapidly to the sea by means 

 of a number of long narrow valleys unconnected with each other; 

 on the eastern side the hills are quite as abrupt, but the descent is 

 broken by a large tableland occurring midway between the summit 

 and the sea-level, which occupies about one-fourth of the entire 

 superficies of Aden. The plateau is intersected with numerous ravines, 

 nearly all of which converge into one valley, which thus receives a 

 large proportion of the drainage of the peninsula. Thus we can 

 easily understand how the steepness of the hills, the hardness of the 

 rocks, and the scarceness of the soil upon them combine to prevent any 

 great amount of absorption. Almost perpetual drought is, of necessity, 

 the consequence of such physical and meteorological conditions. 



Aden has been described by Ibn Batuta as a large city without 

 either seed, water, or tree. 2 But it is not so entirely destitute of 



~ *~Cf. H mter, E. C. 



2 Travels of Ibn Batuta ; translated by the Rev. Samuel Lee, London, 1 829, page 55 . 



