Theories and Experiments 279 



basis of his whole physiological argument, we see that his position 

 is untenable. 



I should certainly not have spent so much time on a work 

 which has had far too much publicity, if it was not still quoted 

 as an authority by persons who preferred to trust to its peremptory 

 conclusions rather than to make the painful analysis through the 

 meanderings of which we have led our readers. And the latter 

 have had the opportunity to see that even if the a priori asser- 

 tions and the statements of conclusions are clear, the experiments 

 themselves and the calculations based on them contain only ob- 

 scurity, confusion, or error. 



M. Gavarret 116 did not adhere to the theory which we reported 

 above, and which he had given in the form of advice to M. Leroy 

 de Mericourt. When he wrote the article Atmosphere for the 

 Dictionnaire Encyclopcdique, he was led to investigate the effects 

 of decreased pressure, without the addition of fatigue, exertion, 

 and the production of carbonic acid imposed by mountain ascents. 

 Reaching the study of causes, as an experienced physicist, he first 

 opposes the opinion that the lessening of the weight sustained by 

 the body may have some effect; he properly invokes against this 

 error the principle of the incompressibility of liquids, and conse- 

 quently of the body. But in giving his attention to this point, 

 strangely enough, he returns to the ideas of Robert Boyle: 



The disturbance which accompanies the decrease of the barometric 

 column is really the effect of the pressures from within outward 

 exerted by the vapors and the gases imprisoned with the body .... 

 We must fix our attention upon the gases of the blood which, under 

 the effect of a considerable and very rapid drop of the barometric 

 column, may cause serious symptoms. The blood, in fact, contains 

 oxygen, nitrogen, and carbonic acid in the state of simple solution. 

 When the outer pressure diminishes, these gases tend to separate from 

 the blood, push the walls of the vessels from within outwards, and 

 distend the pulmonary and general capillaries, the walls of which may 

 be ruptured because of their thinness and lack of resistance. Such 

 is the mechanism of the production of hemorrhages, sometimes slight 

 and temporary as their determining cause when they appear on ex- 

 ternal surfaces, sometimes serious and even fatal, when they have the 

 interior of some vital organ as their seat. (P. 153.) 



But M. Gavarret makes haste to apply a proper restriction to 



this: 



Symptoms of this sort may no doubt be produced in persons who 

 are very rapidly moved to great altitudes; but that is not the case 

 with travellers who gradually ascend from sea level to the highest 

 plateaux on earth. In the latter, the laws of physics governing gases 

 and their solubility .... reestablish harmony .... (P. 154.) 



