Letter from M. Humboldt to C. Delambres. 163 



greater rarity of the air. We ascended 500 toises higher 

 than Condamine (on Carazon), and on Chimborazo we 

 carried our instruments to the height of 3031 toises, where 

 we saw the barometer fall to 13 inches 11*2 lines : the ther- 

 mometer was at 1*3^ below zero. We still bled at the lips ; 

 our Indians deserted us as usual ; C. Bonpland, and M. Mon- 

 tiifar, son of the marc[uis de Salvalegre of Quito, were the 

 oulv persons who remained. We all experienced an unea- 

 siness, clLbility, and desire to vomit, which certainly arose 

 as much from the want of oxygen in these regions as from 

 the rantv of the air. At that immense height 1 found only 

 (V20 of oxvgen. A frightful chasm prevented us froni 

 reaching; the summit of Chimborazo, of which we were 

 within 236 toises. You know that a great uncertainty still 

 prevails in regard to the height of this colossus, which La 

 Condamine measured only at a very great distance, assign- 

 ing to it the height of nearly 3220 toises, whereas Don .Tuan 

 makes it 3380 toises ; nor does this difference arise from the 

 different heights which these astronoraeis adopted for the 

 signal of Carabura. I measured in the plain of Tapia a base 

 of 1702 metres. Pardon me if I speak sometimes of toises 

 and sometimes of metres, according to the nature of my in- 

 struments. You know that in publication every thing may 

 be reduced to the metre and centigrade thermometer. Two 

 geodosic operations gave me for Chimborazo 3267 toises 

 Above the level of the sea ; but the calculations must be recti- 

 fied by the distances of the sextant from the artificial horizon 

 and by other circumstances. The volcano of Tunguragua 

 has decreased a great deal since the time of La Condamine : 

 instead of 2620 toises I found no more than 2331 ; and, in 

 my opinion, this does not arise from an error in the opera- 

 tions, because in my measures of Cayambe, Antisana, Co- 

 topaxi, and Iliniza, I seldom differ ten or fifteen toises 

 from the results of La Condamine and liouguer. 'I'he iut 

 habitants of these unfortunate countries all say that Tungu- 

 ragua has visibly decreased in heiglit : on the other hand, I 

 find that Cotopaxi, which has been subject to such immense 

 ;.'xplosi(>ns, is of the same height as in 1744, or rather 

 somewhat higher. But the stony summit of Cotopaxi in- 

 dicates that ft is a chimney, which resists and retains its 

 figure. The operations we made from January to July in 

 the Andes of Quito gave to their inhabitants the dismal in- 

 telligence that the crater of Pinchincha, which La Conda- 

 mine saw full of snow, burns an:ain ; and that Chimborazo, 

 which was thought to he so peaceable and innocent, has 

 been a volcano, and perhaps will one day be so again. We 



found 



