68 Tableau of High Asia. [No. 1, 
the atmospheric pressure is, at a height of about 18,600 or 18,800 ft., 
one-half of that at the level of the sea. At an elevation of 22,200 ft. 
(so trivial a height when compared with the extreme upper limit of the 
atmosphere), we observed a barometrical pressure of 13.364 inches, so 
that nearly three-fifths of the weight of the atmosphere lay below the 
point reached by us at the time. 
Tt is evident that there must be a limit beyond which the degree of 
rarefaction is mcompatible with the conditions of human existence ; 
but it will ever remain extremely difficult to determime the line of 
demarcation, with any approach to scientific precision. 
The influence* which height exercises upon man, varies with 
the individual ; a man in good health having the chance of less suffer- 
ing. The difference of race has apparently no appreciable importance. 
Our Hindu servants suffered far more from the cold than our Tibetan 
companions, though not more from the diminished pressure. For the 
generality of people the influence of height begins at 16,500 ft., a 
height nearly coinciding with that of the highest pasture grounds 
visited by shepherds. 
The complaints produced by diminished pressure are,—headache, 
difficulty of respiration, and affection of the lungs, the latter even pro- 
ceeding so far as to occasion blood-spitting, want of appetite and even 
sickness, muscular weakness, and a general depression and lowness of 
spirits. Bleeding of the nose we experienced ourselves, though very 
rarely, the loss of blood on such occasions being insignificant; but 
bleeding of the ears and lips we neither experienced personally, nor 
observed in others during our travels in High Asia. Humboldt,+ 
however, states, that on the Antisana, at a height of 18,141 ft., his 
companion, Don Carlos Montufar, bleeded heavily from the lips, and 
that during the ascent of the Chimborazo, every one suffered from 
bleeding of the lips and even the gums. 
The effects here mentioned, which disappear in a healthy man 
almost simultaneously with his return to lower regions, are not sen- 
sibly increased by cold, but the wind has a most decided influence for 
* Notices and remarks on this subject are to be found in “ Gleanings in 
Science,” Vol. 1., p. 330; Gerard’s “ Koonawur ;” Hooker's “ Himalayan Jour- 
nals,’ Vol. II., p. 413; Thomson’s “ Western Himalaya and Tibet,” p. 185 and 
p. 433. 
+ “ Kleinere Schriften,’ Vol. I., p. 148. 
