multitude of hares and roe-deer which, caught unawares, ran off in all 

 directions. 



The trail-rope has another important function. At the moment of 

 landing, it directs the balloon into a position suitable for operations. 



The bathyscaphe, too, is provided with a trail-rope which plays the 

 same part as with the free balloon : it unballasts the submarine at the 

 moment when it approaches the bottom and thus decreases the landing 

 shock. It maintains the submarine in stable equilibrium in the vicinity 

 of the bottom and if a light current of water moves the ship, it allows 

 the passengers to observe the bottom from close at hand, while the 

 cabin moves about slowly at an altitude of a fathom or so following 

 the folds of the ground. During this trip the trail-rope attached to the 

 stern of the float also orientates the bathyscaphe in such a fashion as 

 to place the observation window in front. That is why I equipped the 

 FNRS 2 and the Trieste with a trail-rope and why I have recommended 

 its use to the French Navy. 



The trail-rope of the free balloon is generally made of hemp: 

 as ours had to be weighty, even under water, I used metallic cables; 

 as it had to be more flexible than would be a single cable of the right 

 weight, I employed a series of relatively thin cables which, combined, 

 formed what I have called a ' horse-tail '. The FNRS j, on the other 

 hand, was provided with a heavy chain which offers the advantage of 

 great flexibility. However, on a soft terrain, the friction of the chain 

 is considerable: this can in certain cases bring the bathyscaphe to a 

 complete standstill. 



If, as is generally the case in the Atlantic, the water, even at great 

 depths, is moving at a certain speed, the bathyscaphe will be able with- 

 out any other aid to prospect a long strip of terrain. In many places, 

 however, for example in the Mediterranean, the current is too weak 

 to overcome the friction of the trail-rope : sometimes indeed there is 

 no current at all. In such a case the observers, during the whole extent 

 of the dive, could not observe more than a few square yards of the 

 bottom : the scientific results from such a dive would be almost nil. To 

 remedy this, the bathyscaphe should be endowed with its own power 

 of movement. It must then, from being a free balloon, be transformed 

 into a dirigible balloon. That is why we equipped each of the three 

 bathyscaphes with two electrically driven propellers, one to port and 

 one to starboard. The pilot operates each of these two propellers 

 separately and can vary the direction and speed of rotation. Thus he 



[36] 



