Although these curious spots seem perfectly level, all those in this direction have a gentle slope to the northeast: thither the rain-water, which sometimes covers them, gently gravitates. This, it may be recollected, is the direction of the Zouga. The salt dissolved in the water has by this means all been transferred to one pan in that direction, named Chuantsa; on it we see a cake of salt and lime an inch and a half thick. All the others have an efflorescence of lime and one of the nitrates only, and some are covered thickly with shells. These shells are identical with those of the mollusca of Lake Ngami and the Zouga. There are three varieties, spiral, 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 slightly 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 this view seems supported by the fact that the largest quantities of salt have been found in the deepest hollows or lowest valleys, which have no outlet or outgoing gorge; and a fountain, about thirty miles south of the Bamangwato--the temperature of which is upward of 100 Deg.--while strongly impregnated with pure salt, being on a flat part of the country, is accompanied by no deposit.
When these deposits occur in a flat tufaceous country like the present, a large space is devoid of vegetation, on account of the nitrates dissolving the tufa, and keeping it in a state unfavorable to the growth of plants.
We found a great number of wells in this tufa. A place called Matlomagan-yana, or the "Links", is quite a chain of these never-failing springs. As they occasionally become full in seasons when no rain falls, and resemble somewhat in this respect the rivers we have already mentioned, it is probable they receive some water by percolation from the river system in the country beyond. Among these links we found many families of Bushmen; and, unlike those on the plains of the Kalahari, who are generally of short stature and light yellow color, these were tall, strapping fellows, of dark complexion. Heat alone does not produce blackness of skin, but heat with moisture seems to insure the deepest hue.
One of these Bushmen, named Shobo, consented to be our guide over the waste between these springs and the country of Sebituane. Shobo gave us no hope of water in less than a month. Providentially, however, we came sooner than we expected to some supplies of rain-water in a chain of pools. It is impossible to convey an idea of the dreary scene on which we entered after leaving this spot: the only vegetation was a low scrub in deep sand; not a bird or insect enlivened the landscape. It was, without exception, the most uninviting prospect I ever beheld; and, to make matters worse, our guide Shobo wandered on the second day. We coaxed him on at night, but he went to all points of the compass on the trails of elephants which had been here in the rainy season, and then would sit down in the path, and in his broken Sichuana say, "No water, all country only; Shobo sleeps; he breaks down; country only;" and then coolly curl himself up and go to sleep. The oxen were terribly fatigued and thirsty; and on the morning of the fourth day, Shobo, after professing ignorance of every thing, vanished altogether. We went on in the direction in which we last saw him, and about eleven o'clock began to see birds; then the trail of a rhinoceros. At this we unyoked the oxen, and they, apparently knowing the sign, rushed along to find the water in the River Mahabe, which comes from the Tamunak'le, and lay to the west of us. The supply of water in the wagons had been wasted by one of our servants, and by the afternoon only a small portion remained for the children. This was a bitterly anxious night; and next morning the less there was of water, the more thirsty the little rogues became. The idea of their perishing before our eyes was terrible. It would almost have been a relief to me to have been reproached with being the entire cause of the catastrophe; but not one syllable of upbraiding was uttered by their mother, though the tearful eye told the agony within. In the afternoon of the fifth day, to our inexpressible relief, some of the men returned with a supply of that fluid of which we had never before felt the true value.