which the plug is forced by a nut m and, on the outside, by six screws. 

 The rubber ring k doubles the security. The essential thing is that the 

 cable should not be driven into the cabin by outside pressure. With 

 this in view, it is brazed to the conical ring c which rests on the inside 

 of the plug d. At a depth of 3 J miles the longitudinal force that the 

 water exerts upon the cable is 2640 lb. If the cone c has a height of 

 •4 in. the brazing is extended over a surface of 0-77 sq. in., and 

 it is then subject to a shearing stress of 3410 lb. per sq. in. If the 

 brazing is well done there is no danger whatever there. My son him- 

 self superintended the carrying out of the brazing. He ascertained that 

 in every case the silver ran well into the joint. For additional security, 

 another ring b was brazed to the cable : furthermore, the cable was held 

 tight on the outside by a steel clamp. The jaws of this clamp had had 

 small grooves machined in their faces to prevent the cable from sliding 

 between them. In the laboratory we attempted to force a ' Pyrotenax ' 

 cable through a clamp of the same construction. A force of 13,200 lb. 

 was not enough to displace it. After this test we observed that the 

 machined jaws of the clamp had become embedded in the copper of the 

 cable. No sliding was therefore possible. I think that in this construc- 

 tion we carried security farther than was necessary. But the practical 

 result is that during the dives, seated before the porthole, the idea 

 didn't even occur to us that the cables could be transformed into a 

 deadly projectile. 



It was not only necessary to see that the entire cable was not dis- 

 lodged. We also had to be sure that the core of the cable would not 

 slide in its sheath. This danger is avoided by the friction that the com- 

 pressed insulating asbestos produced all along the cable. Besides, a 

 certain number of bends in the cable would alone have prevented any 

 displacement of the core and finally the extremity of the core was 

 made safe. 



We are therefore certain that the passage of our cable offers all the 

 necessary strength. But we must also prevent all infiltration of water. 

 It is here that we made use of Araldite D, poured into the plug g. 

 As this resin is very hard, it is necessary to anticipate the possibility of 

 its cracking as a result of a deformation of the metal. That is why we 

 poured in upon the Araldite a soft wax h that the engineers of the 

 Pirelli Company made specially for us and which has been given the 

 name of 'bathycire'. This wax, liquid at high temperatures, is soft at an 

 ordinary temperature. It offers an extraordinary adhesiveness to solid 



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