Their splendid physical development and form of skull show 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 European 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 comparatively 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 remarkable 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 increased 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".