rapid advance of the Allies across Belgium had prevented their use. 

 It would have been a curious trick of fate if these vessels, instead of 

 helping to propel engines of death and destruction through the strato- 

 sphere, had been used for the scientific exploration of the submarine 

 deeps. One can see here another example of the analogy between 

 aeronautics and submarine navigation. (These remains of the Vis 

 unfortunately were lost to us at the last moment.) 



A fresh analogy: the tanks were supplied to us in the end by the 

 Etablissements Georges L'Hoir of Liège, who had previously con- 

 structed the aluminium cabins for the stratospheric balloon FNRS. 



The seven aluminium tanks were placed vertically upon a steel 

 framework which supports the cabin (Fig. 5). The Mercantile Marine 

 Engineering Company, of Antwerp, generously took upon itself to 

 supply the envelope and arrange the whole rigging of the bathy- 

 scaphe.l 



THE SOURCES OF THE ELECTRIC CURRENT 



To supply the current needed for the lighting and propulsive 

 equipment we had to have a considerable source of power: a lead 

 acid battery of 14 cells and 900 ampere-hours as well as a small reserve 

 battery of 12 cells. The large battery, arranged in two iron caissons, 

 was held beneath the float by two electro-magnets, as we have already 

 said. The caissons were filled with oil and were connected with the 

 sea : this oil was consequently at the same pressure as the water. The 

 pressure could have no influence on the electro-chemical reactions of 

 the batteries because the volumetric variations which accompanied 

 them were slight: for the rest, the tests which we had made in our 

 pressure chamber had proved it. There is no point in spending any 

 more time on the special details of the FNRS 2. All the principles of 

 its construction were repeated in that of the Trieste and above all in 

 the FNRS 3. Profiting by experience we naturally introduced im- 

 provements into the two latter, which we shall mention later. 



1 We take this opportunity of thanking them cordially, as well as their 

 director and chief engineer, M, de Bièvre. 



[5°] 



