AN ARTIFICIAL LUNG. 247 



This pipe is furnished with a valve, which perinite 

 the expulsion of air, but opposes the entrance of 

 water. The steel reservoir is separated from the 

 air-chamber by a conical valve opening from the 

 air-chamber towards the reservoir in such a manner, 

 as to open only by the influence of an exterior 

 pressure — the pressure of the air in the reservoir 

 tending to close it. 



It is obvious that the use of this apparatus renders 

 the regular working of the air-pump unnecessary. 

 The air which it transmits to the diver is stored up 

 in the steel reservoir. From this store the diver 

 can supply his needs without fatigue in the following 

 manner. 



The air-chamber is closed by a moveable lid, to 

 which is attached the tail of the conical valve. The 

 diameter of the lid is somewhat less than the interior 

 diameter of the chamber, and it is covered with caout- 

 chouc to render it airtight. It yields to both 

 interior and exterior pressure — the former causing 

 it to rise, the latter to fall. 



When exterior pressure is exerted on this lid, 

 the valve is immediately affected through the in- 

 termediary tail or rod ; communication between the 

 reservoir and the air-chamber is opened, and 

 a portion of the compressed air flows into the 

 chamber. Should the latter contain an excess of 



