enormous pressure of the water from squeezing out, however slightly, 

 the edges of the washer, while the middle portion of the washer would 

 remain in place. The pressure between the two hemispheres will then 

 be decreased towards the edge of the joint and increased towards the 

 middle. This non-uniformity of stress would impair the strength of 

 the whole construction. So we had to give up the idea of an interposed 



Fig. 4. FNRS 2-FNRS 3. Clamp for the two hemispheres 



a. 



b. 



\ 

 / 



Hemispheres 



c. Rubber 



d. Steel clamp 



layer and make use of the autoclave joint. The principle is very simple : 

 the two hemispheres are placed directly one against the other, and on 

 the exterior of the cabin the joint is surrounded by a band of rubber. 

 The pressure of the water forces this rubber against the metal and it is 

 perfectly leak-proof provided that the two hemispheres are fitted 

 against each other exactly, in other words, on condition that the 



[47] 



