machining is faultless. If anything should penetrate the fissure, it would 

 be the rubber. Let us add, to be exact, that this sort of joint, however, 

 should not be used under pressure much greater than those in question 

 in our case, for then the rubber would become hard and brittle. 



While the Trieste was resting on the bottom of the Tyrrhenian Sea 

 under a pressure of 325 atmospheres, I carefully examined the great 

 joint of the cabin : I did not find a single drop of water in it. 



THE FLOAT 



It is the petrol contained in the float which must carry the whole 

 weight of the bathyscaphe. The cabin with its contents has a weight 

 of 1 1 tons : but it only displaces 5 • 5 tons of water. Its apparent weight 

 is then only 5 • 5 tons — the weight that the float must carry. If, in round 

 figures, the density of the petrol is 0-65 tons per cubic metre, and that 

 of the water at the surface of the sea is i -02 tons per cubic metre, each 

 cubic metre of petrol will carry 0-370 of a ton. The volume of petrol 

 necessary to carry the cabin and its contents should then be 



^ '^t 

 — ^-^—- = 14-8 cu. m.= 522-7 cu. ft. 



o-37t/m^ 



One must also take into account the weight of the metallic parts 

 of the float, of the heavy storage batteries and of other loads, and 

 lastly of the contraction of the petrol due to the low temperatures and 

 to the pressures of the great deeps. On the other hand we had to have 

 a reserve of petrol to take care of a possible leak, or to free us if we 

 were caught in floating seaweed, the mud at the bottom or any other 

 obstacle, or again to compensate a possible difference of density 

 between the petrol allowed for and the petrol supplied. All these 

 considerations reckoned in, we were led to fix the volume of the float 

 at 1059 cu. ft. (30 cu. m.).l 



All this petrol was contained in six upright cylindrical tanks, as is 

 shown in Fig. 5. Between these cylinders was placed the small vessel 

 containing the driving petrol and the ballast tanks. All this was sur- 

 rounded by a casing of iron sheeting 0-04 in. thick which should in a 

 certain measure protect the petrol tanks, decrease the hydraulic 

 resistance opposing the movements of the bathyscaphe and retain 

 any petrol which might leak from a reservoir: finally, one could by 



1 For the Trieste the volume was increased to 3742 cu, ft., this last bathyscaphe 

 being stronger and therefore heavier. 



[48] 



