had to be replaced by a pin in the shape of a truncated cone in ' in- 

 defatigable' steel, having the apex of the cone coinciding with the 

 centre of the sphere. The stresses being everywhere perpendicular to 

 this conic surface, the strength of the sphere was in no way affected. 



The sample taken out showed bubbles with diameters rising to 

 J in., but which, in the opinion of specialists in steel, would not too 



Fig. 3. Cabin of the FNRS 2, the FNRS 3 and the Trieste^ without the clamping 



device 

 a. Forward porthole b. Passages for electric cables c. Door porthole 



greatly impair the strength of the cabin. I agreed with this, while still 

 making up my mind to have the bathyscaphe make dives while empty, 

 down to a depth which would exceed by 50% that to which we in- 

 tended to descend ourselves. I considered this an elementary pre- 



caution. 



1 



Fig. 3 shows the cabin in section. The casting as well as the machin- 

 ing would have been impossible if the cabin had had to be in a single 



1 I wish here to express my gratitude to the Établissements Henricot and thank 

 them for the trouble they have taken. 



[43] 



