84 NATURAL DIVISIONS OF AFRICA. 



that, but for the black skin and woolly hair, they would 

 take rank among the foremost Europeans. 



The next division, that which embraces the centre of 

 the continent, can scarcely be called hilly, for what hills 

 there are are very low. It consists for the most part of 

 extensive, slightly undulating plains. There are no lofty 

 mountains, but few springs, and still fewer flowing streams. 

 Rain is far from abundant, and droughts may be expected 

 every few years. Without artificial irrigation no Ruropean 

 grain can be raised, and the inhabitants (Bechuanas), 

 though evidently of the same stock, originally, with those 

 already mentioned, and closely resembling them in being 

 an agricultural as well as a pastoral people, are a com- 

 paratively timid race, and inferior to the Caffres in physical 

 development. 



The western division is still more level than the middle 

 one, being rugged only near the coast. It includes the 

 great plain called the Kalahari Desert, which is remark- 

 able for little water and very considerable vegetation. 



The reason probably why so little rain falls on this 

 extensive plain is, that the prevailing winds of most of the 

 interior country are easterly, with a little southing. The 

 moisture taken up by the atmosphere from the Indian 

 Ocean is deposited on the eastern hilly slope ; and, when 

 the moving mass of air reaches its greatest elevation, it 

 is then on the verge of the great valley, or, as in the case 

 of the Kalahari, the great heated inland plains ; there, 

 meeting with the rarefied air of that hot dry surface, the 

 ascending heat gives it greater capacity for retaining all 

 its remaining humidity, and few showers can be given to 

 the middle and western lands in consequence of the in- 

 creased hygrometric power. 



This is the same phenomenon, on a gigantic scale, as 

 that which takes place on Table Mountain, at the Cape, 

 in what is called the spreading of " the table-cloth." The 

 south-east wind causes a mass of air, equal to the diameter 

 of the mountain, suddenly to ascend at least three thousand 

 feet ; the dilatation produced by altitude, with its 

 attendant cold, causes the immediate formation of a cloud 

 on the summit ; the water in the atmosphere becomes 

 visible ; successive masses of gliding-up and passing-over 

 air cause the continual formation of clouds, but the top 

 of the vapoury mass, or " table-cloth," is level, and 

 seemingly motionless ; on the lee side, however, the thick 



