Theories and Experiments 445 



We see that his physiological attempt has been unsuccessful 

 and that he must return to explain, not the symptoms, but the re- 

 sistance of the diver to "this force whose principle is unknown, 

 but which changes the general law." It was really useless then 

 to take so much trouble to try to apply these laws. 



Further on, mentioning the two principal inconveniences of the 

 diving bell, the pains in the ears and the confinement of the air, 

 Brize-Fradin proposes as remedies: 



1. To put cotton in the auditory canal, to imitate "the Creator, 

 omniscient in his works, who distributed in the organ of hearing 

 this cerumen which . . . assists the harmony of the sound waves" 

 (p. 131); 



2. To bring oxygen into the bell by means of a force-pump 

 "when the sea has been drained out of the bell by these air- 

 drums"; but he recommends "that only exact quantities should be 

 introduced, which should never exceed a tenth of the quantity of 

 vital air ... . for an excess would produce a harmful sensitivity and 

 disturbance" (p. 183). 



I mention only for the sake of the record the passage in which 

 Halle and Nysten 5 speak of the effect of compressed air; in fact, 

 they merely say: 



In deep mines, the effects resulting from the compression of the 

 air would be more wholesome than harmful, because of the increased 

 quantity of air in the same volume. They would make respiration 

 less frequent, because each inspiration would take effect upon a 

 greater mass of this fluid. 



The increase in the weight of the atmosphere should, it seems, 

 produce less perceptible effects than its decrease, and the pressure 

 which tends to compress all its parts seems less harmful to our 

 organism than their excessive expansion. 



For the same reason I report the opinion of Jaeger, who does 

 not seem to base it on any direct observation: 



Air compressed to a very high degree may cause sudden death, 

 because it produces apoplexy with hemorrhage and prevents the re- 

 turn of the blood to the upper parts and the heart. (P. 97.) 



The experiments of Poiseuille 7 are much more important. 



In the course of his researches, so conspicuous for the scientific 

 spirit and the accuracy which he manifests in them, this author 

 asks himself whether variations in pressure have an effect upon 

 the circulation of the blood. To settle this important question, he 

 uses a pneumatic object-holder composed of an unyielding box, 



