Situation of Zones without Bain, and of Deserts. 367 



conrmerce, and of the Carthagenian power in Africa, and that 

 the English have endeavoured to secure its investigation by 

 their alliance with the Pacha of Tripoli. On the side of Alge- 

 ria, the route of Timbuctoo, by the oasis of Touat, is much less 

 convenient ; the stations are still rarer on the routes from 

 Tafilet to the same town. It results, moreover, from the in- 

 formation obtained by Consul Jackson, that the oases there are 

 liable to lose their springs, — a fact confirmed by the terrible 

 example of 1805, when a caravan of two thousand persons 

 and eighteen hundred camels perished entirely, from having 

 trusted to these subterranean waters. 



But this digression must not make us forget our principal 

 object. The mountains of this median portion of the Sahara 

 do not exercise a very sensible influence on the phenomenon 

 of rain. Thus, in those which are to the west of Mourzouk, 

 rains are so irregular that nine years sometimes elapse without 

 their occurrence ; the rough and rugged district of Haroudje 

 alone exhibits valleys of bright verdure on account of the fre- 

 quency of rain, but we must not forget that it is situated in 

 27° N. According to some travellers, rain is unknown even 

 at Mourzouk (lat. 25° 54' N.) ; and the small quantity of water 

 which falls in the whole of Fezzan is so subject to intermis- 

 sion, that it cannot be depended on for the cultivation of the 

 soil. Some garden products and com are obtained in Decem- 

 ber and January only by the assistance of these springs ; and 

 Captain Lyon only saw three springs which reached the sur- 

 face, the others being found at the bottom of holes dug to a 

 depth of from three to seven yards. The oasis of Fezzan thus 

 presents nothing else but a plain, generally sandy, steril, and 

 destitute of streams worthy of remark ; and this physiognomy 

 continues to Tegerry (lat. 24° 4' N.), where we have, at the 

 same time, the southern limit of the date, and the northern 

 of the Cucifera thebaica, and where, likewise, the rocky band 

 already described commences. 



Let us now place the facts relative to the opposite hemi- 

 sphere beside those regarding the Sahara. The sub-tropical 

 portion of Southern Africa presents to us, between the high 

 regions of the centre of this continent and the mountains of 

 the Cape of Good Hope, another series of deserts placed in a 



VOL. XXXVII. NO. LXXIV. OCTOBER 1844. 2 A 



