Decreased Pressure 979 



I shall end this review of works published since the publica- 

 tion of the principal results obtained in my research by a short 

 analysis of the new book of M. Jourdanet.- 2 This important work, 

 whose appearance I announced and some passages of which I 

 quoted in the first part of my present work, is divided into five 

 parts. In the first (vol. I, p. 3-84), entitled "Preliminary Baro- 

 metric Studies", I shall only mention here, without being able to 

 dwell on it, the curious chapter on the modifications of barometric 

 pressure in the geological ages, and their influence on living beings. 

 The second (p. 85-367) , "Climates of Altitudes", contains, besides 

 a masterly description of lofty, inhabited regions of the globe and 

 important statistics about Mexico, a summary of my own experi- 

 ments, and the study of the influence exerted by decompression 

 on travellers (mountain sickness) and on the inhabitants of lofty 

 regions. In the third part (vol. II, p. 3-154) "Pathological Consti- 

 tution of Altitudes", M. Jourdanet develops and supports by very 

 interesting medical observations his remarkable discovery of the 

 depressing influence of great heights, of the anemic state (anoxy- 

 hemic) of the dwellers in high places when they are attacked by 

 some disease. The fourth part (p. 155-204) deals with "Mountain 

 Climates". M. Jourdanet explains in the following terms the mean- 

 ing he attributes to this word, opposed to that of the climate of 

 altitudes: 



I call altitude climates those which a sufficient elevation, com- 

 bined with the distance to the Equator, characterizes by the certain 

 signs of a respiratory alteration, as a consequence of the diminution 

 of the density of the surrounding air. 



Below this physiological limit, since the barometric decompres- 

 sion does not act in a way harmful in itself, and may on the contrary 

 produce effects beneficial to health, I apply the term mountain cli- 

 mates to the conditions prevailing at moderate heights and on the 

 lower elevations of the soil in mountainous countries. (Preface, p. 2.) 



In this fourth part are found data and particularly statistics of 

 such a sort as to cause sceptical reflexions on the vivifying air and 

 the fortifying effect of the mountains. Finally, in the fifth part 

 (p. 205-292), under the title of "Natural and Artificial Barometric 

 Transitions", the brief sojourn in mountainous places is very 

 cleverly contrasted with the effect of a prolonged abode; very in- 

 teresting observations are made there, besides, on the therapeutic 

 use of rarefied air. 



We see that only the second part of this important work deals 

 with ground on which we ourselves are quartered. In this book, 



