2: The Cabin 



AFTER the cabin oîÛïqFNRS 2 had been handed over by the Belgian 

 Fonds National to the French Navy, we went to Terni to build a 

 new bathyscaphe. 



Terni, about 60 miles north of Rome, is an industrial centre on the 

 banks of the Marmora, a tributary of the Tiber. In the beginning, 

 before the era of electricity, the falls of the Marmora supplied power to 

 a forge. This developed and became one of the greatest industrial 

 enterprises of Italy, the S octet à per F Indus tria e V Elettricità (Industrial 

 and Electrical Company), which now operates in its original centre 

 vast steel-mills of a very modern type. 



This company bent all its energies to the building of a really 

 faultless cabin.l 



The first, that of the FNRS 2 and the FNRS j, was in cast steel. 

 For the Trieste^ however, it was decided to make it in forged steel, 

 which is stronger and more malleable. 



As a matter of fact every solid that is subjected to stress is deformed. 

 If the stress has not exceeded the elastic limit the part takes its original 

 form again as soon as the load is removed. If this limit has been ex- 

 ceeded, the part, after the unloading, retains a certain deformation, 

 called * permanent deformation'. A still greater stress produces 

 breakage. For certain materials, like glass, this ultimate stress is almost 

 identical with the elastic limit: glass does not sustain permanent 

 deformation, without breaking. Other materials sustain a very great 

 deformation before breaking : they are malleable. Among the ordinary 

 metals, lead presents the greatest malleability. When by accident a 

 component breaks, it is not generally because the load has exceeded 

 that which the broken section should be able to bear : the cause of it is 

 more often that the stresses were not uniformly distributed over the 

 whole section. When an overloaded part breaks, its load passes 

 entirely to the neighbouring parts: these, overloaded in their turn, 

 break. Thus step by step a whole part can yield, although rough 

 reckoning has led one to believe that it was strong enough. If, how- 

 ever, the material shows a sufficient malleability, the overloaded part 



1 Here I should like to express my great gratitude to this company and 

 especially to the engineer, Mr. Flagiello, Director of the Professional School of 

 Terni, who devoted his energy and his art to the manufacture of this component. 



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