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 - - . " - 21,700 English feet, or 20,360 French feet. 



Gualateiri - '- 21,960 " 20,604 



Parinacota ... - 22,030 20,670 " . 



Sahama ..... 22,350 ' Jf 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, Zeits- 

 chrift 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 north-east 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 



