78 
SPRINaS — BUSHMEN. 
Chap. IV. 
some are covered tliickly with shells. These shells are identical 
with those of the mollusca of Lake Ngami and the Zouga. There 
are three varieties—spu'al, univalve^ and bivalve. 
In every salt-pan in the country there is a spring of water on 
one side. I can remember no exception to this rule. The water 
of these springs is brackish, and contains the nitrate of soda. In 
one instance there are two springs, and one more saltish than the 
other. If this supply came from beds of rock salt the water would 
not be drinkable, as it generally is, and in some instances, where 
the salt contained in the pan in which these springs appear has 
been removed by human agency, no fresh deposit occurs. It is 
therefore probable that these deposits of salt are the remains of 
the very sHghtly brackish lakes of antiquity, large portions of 
which must have been dried out in the general desiccation. We 
see an instance in Lake Ngami, which when low becomes brackish, 
and tliis view seems supported by the fact that the largest quan¬ 
tities of salt have been found in the deepest hollows or lowest 
valleys, which have no outlet or outgoing gorge; and a fountain, 
about tliirty miles south of the Bamangwato—the temperature of 
which is upwards of 100°—wliile strongly impregnated with pm^e 
salt, being on a flat part of the country, is accompanied by no 
deposit. 
When these deposits occur in a flat tufaceous country hke the 
present, a large space is devoid of vegetation, on account of the 
nitrates dissolving the tufa, and keeping it in a state unfavourable 
to the growth of plants. 
We found a great number of wells in tliis tufa. A place called 
Matlomagan-yana, or the “ Links,” is quite a chain of these never- 
faihng springs. As they occasionally become full in seasons when 
no rain falls, and resemble somewhat in this respect the rivers we 
have abeady mentioned, it is probable they receive some water 
by percolation from the river system in the country beyond. 
Among these links we found many famihes of Bushmen; and, 
unlilve those on the plains of the Kalahari, who are generally of 
short stature and hght-yeUow colour, these were tall strapping 
fellows, of dark complexion. Heat alone does not produce black¬ 
ness of skin, but heat with moisture seems to insure the deepest 
hue. 
One of these Bushmen, named Shobo, consented to be our 
