Chapter II 

 LOW PRESSURES 



The pressures discussed in this chapter have never reached 

 one atmosphere above normal pressure. Workmen employed on 

 the foundations of bridge piers, and divers in suits are evidently 

 also subjected frequently to these moderate pressures; but since 

 they do not experience any distress there (except pains in the ears 

 at the beginning) and since they come from them with no ill effects, 

 the attention of engineers or physicians has almost never been at- 

 tracted to the phenomena which they might have observed under 

 these conditions. 



The case is quite different for the low pressures which physi- 

 cians use frequently today for therapeutic purposes. Here, on the 

 contrary, delicate observations, of a purely physiological order, 

 have been accumulated, and a study has been made of the effect 

 of slightly compressed air with the same care and following the 

 same method as that of any medicinal substance: that is, on man 

 in good health at first, then in different pathological cases. 



To three French physicians, Junod of Paris, Tabarie of Mont- 

 pellier, and Pravaz of Lyons, is due the honor of having introduced 

 into therapeutics an agent the efficiency of which is noted every 

 day by practitioners and the use of which will become, we are 

 safe to state, more and more frequent. I do not wish to take sides 

 in the quarrel which has arisen among them on the subject of 

 priority of invention; as far as I can judge, it belongs to M. Junod; 

 at least it is he who first had publications on this subject. 



Today, the apparatuses intended for treatment by compressed 

 air are fairly numerous. Establishments are now found: in France, 

 two in Paris, others in Lyons, Montpellier, and Nice; in Germany, 

 at Hanover, Stuttgart, Wiesbaden, Johannisberg, Reichenhall, and 

 Ems; in Denmark, at Altona; in Sweden, at Stockholm; in Scot- 



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