BREATHING IN COMPRESSED AND IN RAREFIED AIR 409 



The criterion of proper working conditions in the caisson is there- 

 fore the wet-bulb temperature. This should stand below 75 F. To 

 maintain this condition it is necessary to ventilate the caisson, pref- 

 erably with air that has been cooled by cold-water radiators; in any 

 case, the ventilation should be adequate to keep down the wet-bulb 

 temperature. The increased expense of ventilation with cooled air 

 would soon be balanced by the greater working efficiency of the men. 

 Constant circulation of the air in the caissons by means of fans assists 

 also in improving the conditions, for it helps to increase dissipation of 

 heat from the body. 



