PART THREE 



IN THE FUTURE 



i: What the dolphin taught us 



ALL those who sail the Atlantic have seen schools of dolphins 

 frolicking near their ship. They dive and emerge : you would think 

 they were at play. Then, disappearing, they swim towards the ship. 

 From high on the bow, one can see them shooting along just under the 

 surface. Before the stempost, leading the ship by only a few yards, 

 they glide along, side by side, far enough away for the water not to be 

 churned by the ship. One thing struck us immediately : to swim at the 

 speed of the Scaldis they did not seem to make the slightest effort. 

 Now we were moving at lo knots. Even if the speed were double or 

 treble that, the sailors told me, the dolphins would still escort us with- 

 out difficulty. Their movements were barely perceptible : although they 

 were swimming near the surface, they did not produce any waves. 

 This proves that the energy developed by them is very slight: they 

 therefore must have a very efficient hydrodynamic shape. 



We know that every body which moves in water must overcome a 

 certain resistance. The energy necessary, in general, increases with the 

 square of the speed. Most of the energy expended is lost in the waves 

 produced. 



An experiment is called for : if one makes a model, in paraffin wax 

 for example, having exactly the shape of the dolphin, and it is towed 

 through water by means of a thread, one might expect that this model 

 too would move without resistance and without causing waves. But 

 this is not the case. The resistance met is considerable, and waves are 

 produced. The waves and the eddies show us where the energy 

 transmitted by our thread goes and is lost. Have we not copied our 

 living model with enough care, the slim body ending in a fish-tail.'^ 

 That is not the trouble. All attempts made to copy the best swimmers, 

 as for example the trout, have given the same result : but the trout has 

 the same skill and can move near the surface without producing a 

 furrow. But the phenomenon is easier to observe in the dolphin, which 

 has the curious habit of going ahead of a ship. What then is the secret 

 and the exact mechanism of the displacement of these swimmers.'* 



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