CHAP. XIX. 3I0UNTAIN SICKNESS. 383 



Prof. Bert, in mentioning them, got close au fond du sujet, and 

 then skipped away from an nnpleasant topic. Was this because 

 the facts did not agree with his theory ? He seemed to fail to 

 perceive that the released gas was only that which found a ready 

 outlet, and to take no note of that which remained in the body, 

 without the possibility of immediate escape. 



There are strong grounds for believing that the sudden dizziness 

 and headaches, the slight hemorrhages, the ' mortal pangs ' and 

 ' drunken sensation,^ of which so many have had experience either 

 on land, in balloon, or when sustaining artificial diminution in 

 pressure, and the insensibility and fatal hemorrhages which have 

 occurred in the most extreme cases, have all been caused by 

 internal pressure ; and that the degree of intensity of the effects, 

 and their earlier or later appearance, depend upon the extent of the 

 diminution in pressure, the rate at whicli it is reduced, and tlie 

 leiigth of time it is experienced. An unlimited number of combina- 

 tions can be produced when to these are added the complications 

 arising from the effect on respiration of rarefaction of the air, and 

 differences in individual constitutions. 



The various affections which have been classed together, con- 

 fused and confounded, under the single term Mountain-sickness, 

 are fundamentally caused, as I see the matter, by diminution 

 in atmospheric pressure, which operates in at least two ways ; 

 namely, (A), by lessening the value of the air that can be inspired 

 in any given time, and (B) by causing the air or gas within the 

 body to expand, and to press upon the internal organs. The 

 results which ensue from A are permanent {i.e. so long as the 

 cause exists), and are aggravated the more pressure is reduced. 

 The effects produced by B may be temporary and pass away when 

 equilibrium has been restored between the internal and external 

 pressure ; or they may be fatal, under very large and rapid reduc- 

 tion in pressure.' 



' Of nausea and vomiting I have no experience. Tliey did not happen in the 

 Andes, and they have never occurred either to myself, or to men in my employment, 



