brush c rubbing against the cylinder gave in Morse code the signal a 



(• — ) when the bathyscaphe was rising and n ( ) 



when it was going down. These signals were transmitted to the cabin 

 and a luminous sparking indicated to us the direction and speed of 

 our movement, each revolution of the anemometer corresponding to 

 a determined height. We had thus a true tachometer (a time-speed 

 indicator). So that it would not be disturbed by the conductivity of 

 the sea water, the base of our shaft with its segment-bearing cylinder 

 was placed in a small vessel containing trioline. 



THE INTERIOR LIGHTING OF THE CABIN 



The lighting installation is more important than would be thought 

 at first sight: at all costs we had to prevent the observer from being 

 dazzled. 



I remember an excursion during which, on a day of brilliant sun- 

 light — it was in 19 16 — I penetrated into a grotto of the Jura Mountains 

 in Vaud, Switzerland. I had indeed a compass with a luminous needle ; 

 but without shining my flash lamp on it I could not observe it: my 

 retina retained a * memory ' of the daylight. I recalled this episode when 

 I installed the internal lighting of the cabin: the majority of phos- 

 phorescent animals are scarcely brighter than a luminous compass- 

 needle. 



I distributed in the top of the cabin six small incandescent bulbs, 

 thus lighting up only the white-painted ceiling, and achieving a system 

 of indirect lighting that looked quite up-to-date. Each bulb had its 

 own switch. One of the bulbs was of thirty watts : the five others of 

 5 watts. In our little cabin, where almost all the instruments were 

 painted white, a 5 -watt bulb would be quite enough for the occupants 

 to see by clearly. To carry out a delicate operation, the six bulbs would 

 have to be alight at the same time. For observation of the exterior, 

 they would generally all have to be out. 



We also had large independent flash lamps with which to throw a 

 bright light on a small area. They would be valuable in case of a break- 

 down of the electric current — which, however, never took place. 



During the Capri dive, at one moment I put out my flash lamp, 

 and finding myself in complete darkness placed it on a little shelf 

 within reach. As ill-luck would have it, this happened to be the battery 

 of accumulators controlling the ballast ! Immediately a shower of little 

 sparks appeared, and we heard the crackling of a short-circuit. It is 



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