March, 1835. passage of Cordillera. 393 



noticed at greater length." It would be extremely rash to 

 affirm that the eastern chain in Bolivia, like that of central 

 Chile, must be of subsequent origin to the western one, or 

 that nearer to the Pacific : but excepting through the explana- 

 tion above offered, the circumstance that rivers flowing from 

 a less elevated chain, should penetrate one far more lofty, 

 appears to me quite inexplicable. 



About noon we began the tedious ascent of the Peuquenes, 

 and then for the first time experienced some little difficulty in 

 our respiration. The mules would halt every fifty yards, and 

 then the poor willing animals after a few seconds started of 

 their own accord again. The short breathing from the rarefied 

 atmosphere is called by the Chilenos " puna ;" and they have 

 most ridiculous notions concerning its origin. Some say, 

 " all the waters here have puna ;" others that " where there 

 is snow there is puna ;" — and this no doubt is true. It is 

 considered a kind of disease, and I was shown the crosses 

 over the graves of some who had died " punado." Excepting 

 perhaps in the case of a person suffering from some organic 

 disease of the heart or chest, I should think this must be an 

 erroneous conclusion. A person near death, would probably 

 at this elevation experience a more unusual difficulty in 

 breathing than others ; and hence the effect might be assumed 

 as the cause. The only sensation I felt was a slight tight- 

 ness over the head and chest ; a feeling which may be ex- 

 perienced by leaving a warm room and running violently on 

 a frosty day. There was much fancy even in this; for 

 upon finding fossil shells on the highest ridge, I entirely 

 forgot the puna in my delight. Certainly the exertion of 

 walking was extreme, and the respiration became deep and 

 laborious. It is incomprehensible to me, how Humboldt 

 and others were able to ascend to the elevation of 19,000 

 feet. No doubt a residence of some months in the lofty 

 region of Quito would prepare the constitution for such an 

 exertion ; yet I am told that in Potosi (about 13,000 feet), 

 strangers do not become quite accustomed to the atmosphere 

 for an entire year. The inhabitants all recommend onions 



