Summary and Discussion 493 



sometimes a few hours after leaving the caissons or the diving 

 suits; in one case observed by M. Gal, the paraplegia did not begin 

 until twenty-four hours after the decompression had been made. 

 The time given to decompression is, moreover, extremely variable; 

 in divers, it takes place with a speed which the good advice of M. 

 Denayrouze could not reduce; for the caisson workers, it was at 

 most three or four minutes per atmosphere. 



Slight disturbances, cutaneous, muscular, and articular pains 

 always disappear in a rather short time. The same thing is often 

 true of more serious symptoms, and even of loss of consciousness. 

 But too frequently the paralyses of the lower limbs are persistent, 

 and we have reported numerous observations which make a sad 

 picture of these unhappy men whose sufferings death almost always 

 ends after a period of variable length. In none of the cases which 

 we reported was a paraplegia which lasted more than two days 

 ever completely cured. 



The irregularity between different persons in regard to the 

 effects of decompression is one of the strangest circumstances 

 revealed to us by this study. We have seen by many examples 

 that, of several persons subjected to the same pressure and de- 

 compressed at the same rate, some remained absolutely immune, 

 others had only slight symptoms, whereas one among them might 

 be attacked severely. Similar variations occur in many other cir- 

 cumstances, even a mere departure from the ball shows similar 

 irregularities. But the strange fact about the present case is that 

 these symptoms are attributed, and justly, as we shall prove, to a 

 purely physical cause, and physics should be the same for everyone. 

 But the irregularity does not exist merely between different in- 

 dividuals; it exists in the same person, following circumstances 

 not well determined. It is not rare to see a workman, hitherto 

 spared, attacked when leaving a pressure the same as, sometimes 

 even lower than, those the removal of which he had already 

 endured without any ill effect. The commonplace and ready excuse 

 of alcoholic or other excesses has often been advanced to explain 

 these facts; but sometimes this explanation, which is not one at all 

 from the standpoint of physics, was completely wanting. The only 

 circumstance on which observers agree is the length of the stay in 

 compressed air; the longer it is, the more are the symptoms to be 

 feared, so that certain authors have concluded that the shifts, that 

 is, the intervals of work in the caissons, should be made more 

 numerous, without considering that the decompressions, which 

 cause the symptoms, would thus be increased in number also. 



