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.
The cattle, in rushing along to the water in the Mahabe, probably crossed a small patch of trees containing tsetse, an insect which was shortly to become a perfect pest to us. Shobo had found his way to the Bayeiye, and appeared, when we came up to the river, at the head of a party; and, as he wished to show his importance before his friends, he walked up boldly and commanded our whole cavalcade to stop, and to bring forth fire and tobacco, while he coolly sat down and smoked his pipe. It was such an inimitably natural way of showing off, that we all stopped to admire the acting, and, though he had left us previously in the lurch, we all liked Shobo, a fine specimen of that wonderful people, the Bushmen.
Next day we came to a village of Banajoa, a tribe which extends far to the eastward. They were living on the borders of a marsh in which the Mahabe terminates. They had lost their crop of corn ('Holcus sorghum'), and now subsisted almost entirely on the root called "tsitla", a kind of aroidoea, which contains a very large quantity of sweet-tasted starch. When dried, pounded into meal, and allowed to ferment, it forms a not unpleasant article of food. The women shave all the hair off their heads, and seem darker than the Bechuanas. Their huts were built on poles, and a fire is made beneath by night, in order that the smoke may drive away the mosquitoes, which abound on the Mababe and Tamunak'le more than in any other part of the country. The head man of this village, Majane, seemed a little wanting in ability, but had had wit enough to promote a younger member of the family to the office. This person, the most like the ugly negro of the tobacconists' shops I ever saw, was called Moroa Majane, or son of Majane, and proved an active guide across the River Sonta, and to the banks of the Chobe, in the country of Sebituane. We had come through another tsetse district by night, and at once passed our cattle over to the northern bank to preserve them from its ravages.
A few remarks on the Tsetse, or 'Glossina morsitans', may here be appropriate. It is not much larger than the common house-fly, and is nearly of the same brown color as the common honey-bee; the after part of the body has three or four yellow bars across it; the wings project beyond this part considerably, and it is remarkably alert, avoiding most dexterously all attempts to capture it with the hand at common temperatures; in the cool of the mornings and evenings it is less agile. Its peculiar buzz when once heard can never be forgotten by the traveler whose means of locomotion are domestic animals; for it is well known that the bite of this poisonous insect is certain death to the ox, horse, and dog. In this journey, though we were not aware of any great number having at any time lighted on our cattle, we lost forty-three fine oxen by its bite. We watched the animals carefully, and believe that not a score of flies were ever upon them.
A most remarkable feature in the bite of the tsetse is its perfect harmlessness in man and wild animals, and even calves, so long as they continue to suck the cows. We never experienced the slightest injury from them ourselves, personally, although we lived two months in their HABITAT, which was in this case as sharply defined as in many others, for the south bank of the Chobe was infested by them, and the northern bank, where our cattle were placed, only fifty yards distant, contained not a single specimen. This was the more remarkable, as we often saw natives carrying over raw meat to the opposite bank with many tsetse settled upon it.
The poison does not seem to be injected by a sting, or by ova placed beneath the skin; for, when one is allowed to feed freely on the hand, it is seen to insert the middle prong of three portions, into which the proboscis divides, somewhat deeply into the true skin; it then draws it out a little way, and it assumes a crimson color as the mandibles come into brisk operation. The previously shrunken belly swells out, and, if left undisturbed, the fly quietly departs when it is full. A slight itching irritation follows, but not more than in the bite of a mosquito. In the ox this same bite produces no more immediate effects than in man. It does not startle him as the gad-fly does; but a few days afterward the following symptoms supervene: the eye and nose begin to run, the coat stares as if the animal were cold, a swelling appears under the jaw, and sometimes at the navel; and, though the animal continues to graze, emaciation commences, accompanied with a peculiar flaccidity of the muscles, and this proceeds unchecked until, perhaps months afterward, purging comes on, and the animal, no longer able to graze, perishes in a state of extreme exhaustion. Those which are in good condition often perish soon after the bite is inflicted with staggering and blindness, as if the brain were affected by it. Sudden changes of temperature produced by falls of rain seem to hasten the progress of the complaint; but, in general, the emaciation goes on uninterruptedly for months, and, do what we will, the poor animals perish miserably.