*775• July- <sy>J Likewife Die kunfi natürlichen Brunnen nachzumachen-, (the art of imitating natural mineral waters) by M. Charles le Roi. Likewife Profeffor Bergman’s Opufiula, Vol. I. In the mean while, without denying the advantages that may accrue to any country from poffeflmg thefe warm fprings, it would not be amifs in this place to make fome enquiries concerning their origin. It is well known, that heat, earthquakes, and even fire are produced, when water comes into contaft with fir at a of fulphur mixed With iron. Subterraneous heat or fire produced by this or other caufes, is the occafion of the water exifting in the bowels o f the earth being forced upwards in the form of vapours. A collection of thefe impregnated with the fubftances which they may have diflolved in their way, compofe what we call mineral waters, So that it feems much to be feared, left in fuch confiderable diftillations the water flrould chance to boil over. And, indeed, experience ihows, that, in this cafe, warm fprings and volcanos for the moft part enfue. To conclude, from the number of baths there is at the Cape, and the confiderable degrees of warmth they are pofiefled of, it is probable, that there lies concealed in the bowels of the earth not a little of this burning and all-deftroying element. What gives farther caufe for this fufpicion, is a little rock or hill of ftone, fituated fifteen or twenty paces above the bathing-houfe. This confifts of a folidlava, in which there appear evident marks o f its having been once in a fluid ftate. It likewife perfectly refembles a lava which I had found before in great abundance on the ifland of Afcenfion. This lava too, is in like manner of a very dark colour and contains iron. A l i t — A little piece of road is carried over this fpot, and is diftin- guiihable by a blaekiih duft or powder, like charcoal ciuft, which probably proceeds from the lava or iron ore cruflied to pieces by the wheels of the waggons that pafs that way. But i f any fubterraneous heat or fire ihould be ft?tl concealed hereabouts to a confiderable extent, may it not fo far operate on the fheE or external cruft o f the earth, that much of the humidity of the latter ihall partly evaporate, and partly be dried up in the chinks and clefts which are formed here in its furface. What confirms me in this conjedure is, that though there falls a great deal o f rairr in this part o f Africa, fo that in the rainy feafon the rivers almoft overflow their banks, the greateft part o f them neverthelefs are quite dried up in fummer time. Here are no wells and very few fprings, but abundance of arid' plains covered with fand and heath, of bare mountains, &c. All thefe contribute to give this country the afpeCt of being the moft thirfty and dry trait of land that I have yet feen upon the whole face o f the globe. The warmth o f the Climate here is not fufficient to account for fo great a degree o f aridity ; but the fuppofition of its being occafioned by a fubterraneous heat appears to me by no means abfurd, as- on the ifle of fianna, though rendered fo fertile in other refpeCts by the aihes o f a burning volcano, I obferved two trads o f land fufficiently dry and arid, notwithftanding that a fmall fpot only upon each o f them was fenfibly heated by the fubterraneous fire. Near the" Hottentots Holland's Bath, herbs and fhrubs grow luxuriantly along the tepid ftrearns, which take their rife in the warm fprings, the' roots and items of fome of thefe vegetables being even' U a waihed
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