To provide for this, it would be necessary to double or treble the 

 quantity of emergency ballast available.' It is true. But let us not forget 

 that each of these occurrences is in itself very improbable. Supposing 

 that there is a chance in a thousand for one of them to arise at a given 

 moment, the probability of two simultaneous mishaps is one in a 

 million : it is then less than the danger that each of us runs when we 

 walk in a large city any day. Since we are not afraid to go about town, 

 why should we fear to go down in a bathyscaphe ? In fact, for reasons 

 which we shall see later, the quantity of ballast available in the Trieste 

 is several tons above the 18,260 lb., the sum of the two preceding 

 figures. 



TRAIL-ROPE AND PROPELLERS 



Our bathyscaphe is then endowed with its essential property : it can 

 move about vertically, it dives to the depths, then it rises to the 

 surface and can even remain stable between the two. In that, it re- 

 sembles the free balloon : but the analogy goes further still. 



Each free balloon is furnished with a trail-rope, that is to say, a 

 rope of a length between 33 and 55 yards and of a weight which 

 varies between 44 and 176 lb., which hangs from the car. If the pilot 

 is getting ready to land, he lets the balloon go down with some 

 rapidity: it is important, however, that the balloon should be un- 

 ballasted at the last moment to reduce the shock of contact with the 

 earth. But if the pilot throws overboard only a trifle too much ballast, 

 the balloon rises again. It is here that the trail-rope plays its part. 

 Automatically, when the balloon approaches the earth, the trail-rope 

 is thrown overboard ; but it is taken on board, if the balloon shows any 

 tendency to rise again. Also, if the balloon, in coming down, arrives 

 at a place unsuitable for landing, the pilot can let it 'run on the trail- 

 rope' until he finds a better place. During this last stage of the journey, 

 it is the trail-rope which stabilizes the balloon at a short distance 

 above the ground. In other cases again, even if it is not intended to 

 land, the trail-rope is allowed to trail in order to observe the ground 

 from close at hand. This procedure is above all entertaining, for it 

 gives the passengers much more variety than a trip at a high altitude. 

 I remember, for example, the delight that my passengers felt — they 

 were Swiss aviators, among whom was Bieder, the conqueror of the 

 Pyrenees and the Alps — when one winter day I dragged the trail-rope 

 for many miles above a beech forest which enabled us to discern a 



[35] 



