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Show 218 HYPSOMETRIC ADDENDA. French, or 2851 English feet too high, there are in the western chain of the same country, according to Pentland's map of Titicaca (1848), four peaks to the east of Arica and between lat. 18° 7' and 18° 25', all of which are higher than Chimborazo, which is 21,422 English or 20,100 French feet. These four peaks are- Pomarape - Gualateiri - Parinacota - Sahama 21,700 English feet, or 20,360 French feet. 21,960 20,604 22,030 20,670 22,350 20,971 Berghaus has applied to the eastern and western chains of the Andes of Bolivia the investigation published by me in the Annales des Sciences Naturelles, t. iv. 1825, pp. 225-253, of the proportion (very different in different mountain chains), which the general height of the ridge, the crest, or kamm (the mean height of the passes), bears to the highest summits or culminating points. He finds, following Pentland's map, the mean height of the passes in the eastern chain 12,672 French, or 13,506 English feet; and in the western chain 13,602 French, or 14,895 English feet. The culminating points are 19,972 and 20,971 French, 21,286 and 22,350 English feet; consequently the ratio of the height of the ridge to that of the culminating point is, in the eastern chain, as 1 : 1.57, and in the western chain as 1 : 1.54. (Berghaus, Zeitschrift fur Erdkunde, band. ix. s. 322-326.) This ratio, which is, as it were, the measure of the subterranean elevating force, is very similar to that which exists in the Pyrenees, but very different from the Alps, where the mean height of the passes is less as compared with Mont Blanc. The ratios are, in the Pyrenees, = 1 : 1.43, and in the Alps, = 1 : 2.09. But, according to FitzRoy and Darwin, the height of the Sahama is still surpassed by 796 French, or 850 English feet, by that of the volcano of Acongagua, on the northeast of Valparaiso, in Chili, in S. lat. 32° 39'. The officers of the Adventure and Beagle, in Fitz Roy's Expedition, found, in August 1835, the summit of Acongagua between 23,000 and 23,400 English feet. If we take it at 23,200 (equal to 21,767 Paris feet), this volcano would be 1667 French, or |
