plug and the watertightness is perfect for all pressures ; it is an auto- 

 clave closing. The rubber ring which surrounds the upper rim of the 



/ 



/, 



-k 

 -J 



Fig. 22. Passage of the schnorkel tube through the cabin wall 



plug (drawn in solid black) would, by itself, effect an autoclave closing. 

 It is there to make the safety doubly sure. 



A.fter the bathyscaphe has risen again to iihe surface, the crew 



[ 170 ] 



