“Professor, you must not confound statics with dynamics or you will be exposed to grave errors. There is very little labour spent in attaining the lower regions of the ocean, for all bodies have a tendency to sink. When I wanted to find out the necessary increase of weight required to sink the _Nautilus_, I had only to calculate the reduction of volume that sea-water acquires according to the depth.” “That is evident.” “Now, if water is not absolutely incompressible, it is at least capable of very slight compression. Indeed, after the most recent calculations this reduction is only .000436 of an atmosphere for each thirty feet of depth. If we want to sink 3000 feet, I should keep account of the reduction of bulk under a pressure equal to that of a column of water of a thousand feet. The calculation is easily verified. Now, I have supplementary reservoirs capable of holding a hundred tons. Therefore I can sink to a considerable depth. When I wish to rise to the level of the sea, I only let off the water, and empty all the reservoirs if I want the _Nautilus_ to emerge from the tenth part of her total capacity.” I had nothing to object to these reasonings. “I admit your calculations, Captain,” I replied; “I should be wrong to dispute them since daily experience confirms them; but I foresee a real difficulty in the way.” “What, sir?” “When you are about 1000 feet deep, the walls of the _Nautilus_ bear a pressure of 100 atmospheres. If, then, just now you were to empty the supplementary reservoirs, to lighten the vessel, and to go up to the surface, the pumps must overcome the pressure of 100 atmospheres, which is 1500 pounds per square inch. From that a power——” “That electricity alone can give,” said the Captain, hastily. “I repeat, sir, that the dynamic power of my engines is almost infinite. The pumps of the _Nautilus_ have an enormous power, as you must have observed when their jets of water burst like a torrent upon the _Abraham Lincoln_. Besides I use subsidiary reservoirs only to attain a mean depth of 750 to 1000 fathoms, and that with a view of managing my machines. Also, when I have a mind to visit the depths of the ocean five or six miles below the surface, I make use of slower but not less infallible means.” “What are they, Captain?” “That involves my telling you how the _Nautilus_ is worked.” “I am impatient to learn.”