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The correspondence includes an interesting letter from M.
Humboldt, dated Lima, Nov. 25. 1802, containing an accountof his travels in South America; from which we shall extract ashort description of the province of Quito.
‘This province, which is situated on the most elevated plain in theworld, and which has been rent by the grand catastrophe of Feb.
|483| 4. 1797, has opened a most extensive field of physical observation.Here are volcanoes so enormous as to cause the flame often to ascend3000 feet; which nevertheless do not produce one drop of runninglava, but which vomit forth water, sulphuric hydrogene gas, mud,and carbonated argil. Since the year 1797, the whole of this partof the world has been in agitation: we experience at every instantfrightful shocks: and the subterraneous noise in the plains of RioBamba resembles that of a mountain falling to pieces under our feet.Atmospheric air, and moistened earth, (for all these volcanoes are in adecomposed porphyry,) appear to be the grand agents in these com-bustions and subterraneous fermentations.’
‘It was till now believed at Quito that the rarefaction of the air,at the elevation of 2,470 toises, was the greatest which men could en-dure. In the month of March 1802, we passed some days on thevast plains surrounding the volcano of Antisana, at 2,107 toises ele-vation, where the oxen, when we chased them, vomited blood. On the16th of March, we discovered a path in the snow on which we mount-ed to the height of 2,773 toises. The air contained 0,008 of car-bonic acid, 0,218 of oxygene, and 0,744 of azote. It was not cold, butthe blood gushed out from our lips and eyes. In my expedition of June23, 1802, to Chimboraço, we proved that, with patience, man mightsustain a very great rarefaction of the air. We carried our instru-ments on Chimboraço as high as 3,031 toises, and saw the mercurydescend in the barometer to 13 inches and 11,2 lines.’
By two operations, M.
Humboldt
found the top of Chimbo-raço to be 3,267 toises above the level of the sea. It has oftenbeen asserted, he adds, that this mountain is of granite, but hefound not a single atom. It is a bed of porphyry, 1,900 toisesthick, intermixed with vitreous feld-spath, &o.
The letter closes with a reference to the botanical trea-sures which the writer had discovered: but here we must notdilate; though we cannot help congratulating our readers that,to the bread-fruit-tree and the butter-tree, M.
Humboldt
hasadded the milk-tree, or, as the Indians call it, the vegetable cow.
