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A TEXTBOOK OF PHYSIOLOGY 



are steel chambers filled with compressed air, and provided with air- 

 locks, used for excavating tunnels and foundations of bridges under 

 water. Divers are encased in a dress into which air is umped 

 at a pressure just greater than that of the superincumbent water. 



A 



* *' ..A 

 ' ^'fV-, ****** 



f ^/c 



^ci^ ; ' 



7 v '. .V-'- ' '.' k* '. 

 -"" ".'v ,. ' ' ./' 



.) /&* x% ^ * JK 



/ 



A 



" v. 



FIG. 177. A, NORMAL KIDNEY OF CAT; B, KIDNEY OF CAT UECOMIT.ESSED RAPIDLY 

 FROM EIGHT ATMOSPHERES PREPARED BY SAME METHOD. 



At a pressure of 2 to 3 atmospheres it becomes impossible to whistle 

 or whisper, owing to the density of the air. There are no sensations, 

 beyond this disability, to indicate the abnormal pressure. The pressure 

 in the middle ear has to be equalized by opening the Eustachian 

 tube during the rise of atmospheric pressure. This can be effected 



