376 Historical 



In compressed air, our pulmonary capacity increases, and the 

 movements of our ribs lessen. The excessive pressure which dissolves 

 the oxygen in our finest vasculo-sanguine ramifications makes the 

 action of the thorax unnecessary, and for this reason, our coordinating 

 nervous center reduces it to its minimum of amplitude. 



Economy of strength and time, such is the law which the human 

 spirit follows in the numerous combinations which it makes to keep 

 us in harmony with the world, even when it is a matter of our 

 vegetative life. 



The laborers, when they are working in the caissons, feel fatigue 

 less than in the open air, and do not become so breathless. Hunger 

 seizes them quickly; they sweat a great deal and yet are never thirsty. 



This is the reason for all these phenomena, which are contra- 

 dictory only in appearance. 



The absence of thirst, in spite of enormous loss by sweat, is the 

 result of the great quantity of water which the compressed air holds 

 in solution and forces into the organism. 



The sweat is due to the assistance which our outer tegument 

 never refuses to the lungs, especially in a warm atmosphere, when it 

 is a matter of throwing off much of the muscular materials broken 

 down by work. 



Hunger results from the enormous consumption of our various 

 tissues by the excess of oxygen which penetrates them and by the 

 more energetic contractions of some of them. 



The lessened breathlessness is caused by the circulatory slacken- 

 ing which brings back (towards the lungs, the liver, and the spleen) 

 only a very little venous blood, since there is hardly any, to tell the 

 truth. 



Finally, the absence of fatigue results precisely from the richness 

 of this same nourishing liquid, which unceasingly repairs our muscles 

 at the same time that their own contractions destroy them. 



In compressed air, our secretions are modified; those of the lungs 

 and the skin increase considerably. Those of the alimentary canal, 

 the kidneys and the liver, their converse in many circumstances, do 

 not change, or rather, generally diminish. (P. 12 and 13.) 



When leaving the compressed air, when no illness is to follow, 

 one immediately has a feeling of comfort. It seems as if one breathes 

 as if in spite of himself, that one's chest is full of air, and that one 

 is lighter. That is because there is no longer the heavy weight upon 

 you. (P. 17.) 



Such are the effects produced by the passing action of com- 

 pressed air. According to M. Foley, the workmen who are frequently 

 subjected to it experience phenomena of another sort: 



Any too long period of work within the caisson is divided into 

 two stages: one of benefit, the other of organic loss .... 



As long as the first lasts, the caisson worker has an increased 

 appetite, leaves his work without fatigue, and returns to the open air 

 more alert, more lively, and more eager than usual. He feels stronger 

 and boasts of it with reason, for then the richness of his blood profits 

 him. 



