dimensions as well as weight, we had to use special bulbs much smaller 

 than those normally needed by a filament of looo watts. This obliged 

 us to fill the cases with water to obtain a sufficient cooling of the bulb. 

 The case was provided with a little plexiglas window and an ellip- 

 soidal reflector concentrated the light on this window. Then, a 

 second reflector, parabolic, concentrated the light in a small conical 

 beam. 



Finally, as well as the projectors, we arranged on the outside of the 

 cabin some small incandescent lamps of 35 watts. 



THE ELECTRICITY SUPPLY 



We had to have a source of electrical energy for operating our 

 equipment such as the ventilator, the small lamps, the tachometer, the 

 unballasting apparatus and particularly the driving gear and flood- 

 lamps. In the beginning we had intended to have a lead-acid battery of 

 14 cells and 900 ampere-hours, given to us by Hensemberger. It 

 weighed 2640 lb. and was consequently too cumbersome to be placed 

 in the cabin. Therefore we put it on the deck of the bathyscaphe, in a 

 large vessel filled with petrol. 



As we had cause to regret, the sun of Italy is not an unmixed 

 blessing. Lying in the port of Castellammare, the battery was over- 

 heated to such a point that its polythene cell jars were affected. As there 

 was insufficient time to make new polythene cell jars, we temporarily 

 replaced this large battery by a smaller battery placed in the cabin. It 

 was powerful enough to operate all our lighting apparatus, but the 

 time during which we could operate the motors and projectors, which 

 take a great deal of current, was reduced. 



For our next undertaking Hensemberger furnished us with new cells 

 in silver-zinc. Providing the same energy, they take a quarter of the 

 space and are only a quarter the weight. We could therefore carry in 

 the cabin batteries of the same capacity as at the beginning had had to 

 be placed outside. This made it a lot easier. These cells could be 

 charged in the cabin, since they give out very little gas, and are not 

 corrosive, being free from sulphuric acid. They are not affected if they 

 are completely run down and one does not have to recharge them as 

 soon as they are discharged. This was a great asset to us. We had also 

 a small lead-acid battery placed in the cabin to supply the unballasting 

 apparatus : this was necessary to prevent the loss of ballast and tubs 

 even if the principal battery became completely discharged, as it might 



[lOl] 



