to the main rotor of a helicopter, which will communicate to it a 

 vertical force directed downwards. Thus our mesoscaphe will be a 

 true helicopter in reverse. It will go down under the power of its pro- 

 peller. It will reach equilibrium somewhere near the bottom by decreas- 

 ing the speed of rotation of its propeller and, so as to rise slowly, it will 

 be enough for it to stop its motor. 



To avoid the situation where the reaction of the propeller would 

 make the mesoscaphe turn round on its own axis, we could provide it 

 with two helicopter propellers turning in opposite directions in the 

 style of the large aerial helicopters. I think, however, that it would be 

 better to give it, like the bathyscaphes, two small lateral propellers with 

 horizontal axes, turning normally in opposite directions and balancing 

 the torque of the large propeller. By regulating the speed of rotation 

 of the two small screws, the pilot will be able to steer his ship and move 

 it in all horizontal directions. 



Since the large propeller does not support the apparatus but gives it 

 the power of sinking, a breakdown of the motor would be without 

 serious consequences: it would automatically bring the mesoscaphe 

 back to the surface. 



However, if the particular aim is to explore the sea-bottom, there is 

 nothing to prevent us economizing our electrical energy during the 

 descent and even going down much faster than the propeller is capable 

 of. For this purpose we shall put aboard our little submarine some 

 releasable ballast, just as is done for its big brothers the bathyscaphes. 



As the cabin by itself shows much less resistance to the water than 

 the float of the bathyscaphe, it will be enough to have at our disposal a 

 relatively small quantity of ballast. As it approaches the bottom, the 

 pilot will throw overboard only a portion of the ballast, so as to stabilize 

 his machine as exactly as possible. The vertical manœuvres during 

 observations could then be conducted with a very small consumption of 

 electrical power by the large propeller. For the return journey it will 

 be possible to throw all the ballast overboard, in order to go up very 

 quickly. 



The entire mesoscaphe, fully equipped, would weigh about 5 tons. 

 Any little cargo-steamer would then be able to transport it easily, to 

 launch it and take it back on board, which would very much reduce 

 the cost of operation in comparison with the expenses of an expedition 

 with the bathyscaphe. 



As for the cabin, it could be made of steel like that of the bathyscaphes, 



[ 143] 



