f 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 3,000 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 1,000 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 1,500 lbs. 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 1,000 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 mlles 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."

"To steer this boat to starboard or port, to turn, in a word, following
a horizontal plan, I use an ordinary rudder fixed on the back of the
stern-post, and with one wheel and some tackle to steer by. But I can
also make the Nautilus rise and sink, and sink and rise, by a vertical
movement by means of two inclined planes fastened to its sides,
opposite the centre of flotation, planes that move in every d