CHAPTER 13: Some Figures
"The two hulls are manufactured from boilerplate steel, whose relative
density is 7.8 times that of water. The first hull has a thickness
of no less than five centimeters and weighs 394.96 metric tons.
My second hull, the outer cover, includes a keel fifty centimeters high
by twenty-five wide, which by itself weighs 62 metric tons; this hull,
the engine, the ballast, the various accessories and accommodations,
plus the bulkheads and interior braces, have a combined weight
of 961.52 metric tons, which when added to 394.96 metric tons,
gives us the desired total of 1,356.48 metric tons. Clear?"
"Clear," I replied.
"So," the captain went on, "when the Nautilus lies on the waves
under these conditions, one-tenth of it does emerge above water.
Now then, if I provide some ballast tanks equal in capacity
to that one-tenth, hence able to hold 150.72 metric tons, and if I
fill them with water, the boat then displaces 1,507.2 metric tons--
or it weighs that much--and it would be completely submerged.
That's what comes about, professor. These ballast tanks exist
within easy access in the lower reaches of the Nautilus. I open
some stopcocks, the tanks fill, the boat sinks, and it's exactly
flush with the surface of the water."
"Fine, captain, but now we come to a genuine difficulty. You're able
to lie flush with the surface of the ocean, that I understand.
But lower down, while diving beneath that surface, isn't your
submersible going to encounter a pressure, and consequently
undergo an upward thrust, that must be assessed at one atmosphere
per every thirty feet of water, hence at about one kilogram per
each square centimeter?"
"Then unless you fill up the whole Nautilus, I don't see how you
can force it down into the heart of these liquid masses."
"Professor," Captain Nemo replied, "static objects mustn't be
confused with dynamic ones, or we'll be open to serious error.
Comparatively little effort is spent in reaching the ocean's
lower regions, because all objects have a tendency to become 'sinkers.'
Follow my logic here."