772 



Experiments 



tube. The oscillations of the needle, which correspond to the re- 

 spiratory movements, are, as I have shown, caused by the changes 

 of the intra-thoracic pressure, and their size gives a relative meas- 

 ure of it. 



It is very simple then to examine the tracings one obtains, either 

 at normal pressure or in compressed air. The only precautions to 



