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tion or for sale. It is situated in a plain considerably elevated above the level of the sea, is of an oval form, and about three miles in circumference. It is named Zoutpan or Saltpan, an appropriate name, as the sun and wind do here what is effected in salt-works by artificial heat. When Mr Barrow examined it, the greatest part of its bottom was covered with one continued body of salt, like a sheet of ice, the crystals of which were so united that they formed a solid mass as hard as rock. The dry south-easterly winds of summer, agitating the water of the lake, produce on the margin a fine, light, powdery salt, like flakes of snow. This is equally beautiful as the refined salt of England. Another salt lake, according to Lichtenstein, occurs on the western coast of the colony near to Elephant River, from which the inhabitants of the district supply themselves with this necessary of life. A salt lake of considerable extent is said to occur in about S. lat. 30°, in the upper part of the river-district of the Orange River. The most northern, of which I have been able to gain any intelligence, says Burchell, is one about the 27° S. lat., eastward of Lattakoo. Karroo clay, as already mentioned, is probably a deposite from lake water, at a time when the tracts where it occurs were covered with water.
Particulars to be attended to in investigating the Natural History of Lakes.-Travellers, in examining and describing lakes, ought to ascertain their relations to rivers and springs, their magnitude, depth, temperature at the surface and at various depths, their colours, occultations, and agitations. The water of the lake ought to be submitted to chemical analysis, in order to ascertain whether it is
fresh water, salt water, alkaline water, calcareous water, &c. Their mode of formation ought also to be considered, and the peculiar characters of lakescenery and climate should be attended to.
SOUTH AFRICAN SPRINGS.
The springs of Southern Africa may be divided into common, hot, and mineral.
Common Springs. Although much rain falls in the Cape district, it affords but comparatively few springs. This paucity of springs may be explained, as Mr Barrow remarks, by attending to the nature of the rocks, and their mode of arrangement. Where two of the formations of the district occur together, as sandstone and granite for example, and the sandstone lies upon the granite, whose upper surface is above the level of the neighbouring country, springs will occur abundantly around the line of junction of the two formations. In this case the water percolates through the sandstone, which is a porous rock; but its farther progress downwards is arrested by the granite, which is a dense and compact rock, and therefore, when it reaches the surface of the granite, it accumulates there, and either remains stationary, or flows along its surface, until it finds an opening at the surface, where it issues forth in the form of springs. On the contrary, if the sandstone deposite rests upon granite, whose upper surface is below the level of the surrounding country, the percolating water, on reaching the granite, will accumulate there, and flow off by rents into the lower and distant parts of the country, but few springs will be observed issuing from the sandstone.
Hot Springs. The only hot springs particularly
described by travellers are those of Brand Valley and Zwarteberg.
Brand Valley.-The hot spring here is larger than that at Zwarteberg. It forms a shallow pond of about fifty feet across, of the most transparent water, in the middle of which several strong springs bubble up through a bottom of loose white sand, and afterwards, flowing in a very copious stream, become a rivulet, which, for at least a mile and a half, continues so hot, that its course along the valley may, at any time of the day, but more particularly early in the morning, be traced by the steam which perpetually arises from it. The pond is sheltered by a small clump of white poplars, which thrive perfectly well, although growing at the very edge of the water, and bedewed with the hot steam, which ascends to their highest branches. No plant, it seems, can grow in the water itself; but the margins of the bank are thickly covered with sedge, particularly cyperus fascicularis. Royena glabra, a species of Rhus, and a variety of plants, stand within the influence of its heat. The thermometer, when plunged into the pond, rose only to 144° Fahrenheit, but to the hand it felt nearly scalding hot; so that the immersion could scarcely be endured for a few seconds. The water is pure and tasteless, and is used for all domestic purposes. Nothing resembling a deposition is anywhere observable; nor are its banks or channel at all discoloured. The hill, from the foot of which it issues, has no remarkable appearance; at least, there is none of that black, ponderous iron ore, or earth, noticed at the Zwarteberg baths. At the distance of about 300 yards from the source, two bath-houses have been built over the stream,
the heat of which, even here, is almost greater than can be borne by a person not gradually inured to it. Between the spring and the bath, where the stream has run a sufficient distance in the open air to allow it time to become a few degrees cooler, the bottom of the rivulet is covered with a beautiful sea-green conferva, waving gracefully beneath the water, like long tresses of hair. Specimens of rocks from this district, sent me by Dr Smith, show that the waters of this spring issue from quartz rock, containing grains of white felspar in the state of porcelain earth.
Warm Bath at Zwarteberg.-This is a short mountainous ridge, running east and west, and of secondary height. From the lower part of its southern front projects a small flat hill, out of the upper part of which issue, in several places, hot springs, the waters of which raise the thermometer to 118° of Fahrenheit. The water deposites, in the channels along which it runs, an orange-coloured ochre of iron; but, after a course of 200 or 300 yards, ceases to discolour the ground. It contains iron and sulphur, and hence has a slightly chalybeate taste. Within three yards of these hot springs there rises another, the water of which is pure and tasteless, but is not warmer than that of the common springs of the country. Probably the springs here, as at Brand Valley, issue from quartz rock. In the vicinity of the springs, as I observe by inspection of specimens from Dr Smith, bog-iron ore occurs.
Warm springs also occur in the valley of the Western Elephant River; others near the Eastern Elephant River, in Kamnasi Land; and a third behind Kokman's (Kogman's) Kloof; but all are of lower temperature than those of the Zwarteberg
and Brand Valley. There is also a warm spring on the northern side of the Gariep, in Great Namaqualand.
Springs of mineral waters, of the common temperature, have been noticed in various places; one near Graaf-Reynet, and another not far from Uitenhage, and one also in the Tarka; but their chemical composition has not been accurately ascertained.
Remarks on the Importance of a Knowledge of the Natural History and Chemical Composition of Springs. The springs of the African continent have hitherto been almost entirely neglected by travellers and naturalists, either through indifference or ignorance. Now, however, that scientific men have settled in different parts of that quarter of the globe, particularly in Southern Africa, accurate details may be expected in regard to their various kinds, whether temporary, perennial, intermittent, periodical, spouting, sublacustrine, subfluvian, or submarine; their magnitude and colour; the temperature of common springs at different elevations above the level of the sea, and during different seasons of the year; and the range of temperature of warm and hot springs. But in order to complete the history of the springs of the country, we must, besides, describe not only the rock or rocks from which they flow, but also ascertain the various relations of these rocks to those of the neighbouring mineral formations. Chemical investigations will afford the necessary details as to the different mineral matters that enter into their composition. The remarkable animal substance met with in some European springs, and probably of more frequent occurrence