Re: Propulsion of Jules Vernes' Nautilus

On Aug 10, 10:56 am, j...@xxxxxxxxx (John Dallman) wrote:
In article <Xns9AF5E21EC7BD0tsalagiNOSPAMasus...@xxxxxxxxxxx>,

tsalagiNOS...@xxxxxxxx (Dennis) wrote:
Most remarkable is that Verne says nothing that I can see on how
the battery would be recharged while underway. I can only conclude
that he thought or pretended that there would be enough energy in the
battery at the start that you could run at high speeds for months on
the initial charge, and then you would just construct a new battery!
That, of course, is completely unrealistic.

Science fiction writers do not usually design real breakthroughs in
engineering. They provide aids to the suspension of disbelief, to allow
their story to be told. Verne was probably perfectly well aware of this
flaw, and others: he was certainly aware of the major flaws in, for
example, _From the Earth To the Moon_, where a manned projectile is
launched to the moon by means of a an immense gun, sunk into the ground.
Issues like insufficient gun power, atmospheric friction, and the
reduction of the passengers to a thin layer of squishy red stuff, were
ignored in favour of story.

--
John Dallman, j...@xxxxxxxxx, HTML mail is treated as probable spam.

He usually picked the brains on an expert, I have seen the self-
contained breathing apparatus described in 20,000LUtS compared to a
contemprary (1860s) apparatus..

Here's the passages from the book:

"There is a powerful agent, obedient, rapid, easy, which conforms to
every use, and reigns supreme on board my vessel. Everything is done
by means of it. It lights, warms it, and is the soul of my mechanical
apparatus. This agent is electricity.''
"Electricity?'' I cried in surprise.
"Yes, sir.''
"Nevertheless, Captain, you possess an extreme rapidity of
movement, which does not agree well with the power of electricity.
Until now, its dynamic force has remained under restraint, and has
only been able to produce a small amount of power.''
"Professor,'' said Captain Nemo, "my electricity is not everybody's
and that is all I wish to say about it."
"I will not insist, sir, and I will be satisfied just to be
astonished by such a result. Only one question, however, which you
need not answer if it is indiscreet. The elements which you employ to
produce this marvelous agent must quickly wear out. Zinc, for example,
how do you replace it, since you no longer have any communication with
the surface world?
"Your question will have its answer", Captain Nemo responded, "I
will say to you, initially, that there exists on the sea-bed mines of
silver, iron, zinc, gold, whose exploitation would be doubtless
practicable. But I did not borrow anything from these metals of the
earth, and I wanted to take only from the sea itself the means of
producing my electricity."
"From the sea?"
"Yes, Professor, and I did not miss the means. I could, indeed, by
establishing a circuit between wires plunged to various depths, obtain
electricity by the difference in temperature; but I preferred to
employ a more practical system."
"Which is?"
"You know what sea-water is composed of. In a thousand grams are
found 96 1/2 per cent of water, and about 2 2/3 per cent of chloride
of sodium; then, in a smaller quantity, chlorides of magnesium and of
potassium, bromide of magnesium, sulfate of magnesia, sulfate and
carbonate of lime. You see, then, that chloride of sodium forms a
large part of it. So it is this sodium that I extract from the sea-
water, and of which I compose my ingredients.''
"Sodium?"
"Yes, sir. Mixed with mercury, it forms an amalgam that replaces
zinc in the Bunsen elements. The mercury never wears outs. Sodium
alone is consumed, and the sea itself provides it to me. I will say to
you, moreover, that the cells with sodium must be regarded as most
energetic, and that their electromotive force is double that of the
zinc cells."
"I understand well, Captain, the excellence of sodium under theses
conditions. The sea contains it. But it still must be manufactured,
extracted it in a word. And how do you do this? Your batteries could
obviously be used to power this extraction; but, if I am not mistaken,
the expenditure of sodium required by the electrical apparatus would
exceed the extracted quantity. You would consume more to produce it
than you would produce!"
"So, Professor, I do not extract it by the batteries, but quite
simply employ the heat of the pit coal."
"From the earth?" I insisted.
"Let us say 'coal of the sea', if you wish", answered Captain Nemo.
"And you can work underwater coal mines?"
"Mr Aronnax, you will see me do it. I ask you for an only little
patience, since you have time to be patient. I point out only this: I
owe all to the ocean; it produces electricity, and electricity gives
heat, light, motion, and, in a word, life to the Nautilus."

"There is a powerful agent, obedient, rapid, easy, which conforms
to every use, and reigns supreme on board my vessel. Everything is
done by means of it. It lights, warms it, and is the soul of my
mechanical apparatus. This agent is electricity.''
"Electricity?'' I cried in surprise.
"Yes, sir.''
"Nevertheless, Captain, you possess an extreme rapidity of
movement, which does not agree well with the power of electricity.
Until now, its dynamic force has remained under restraint, and has
only been able to produce a small amount of power.''
"Professor,'' said Captain Nemo, "my electricity is not everybody's
and that is all I wish to say about it."
"I will not insist, sir, and I will be satisfied just to be
astonished by such a result. Only one question, however, which you
need not answer if it is indiscreet. The elements which you employ to
produce this marvelous agent must quickly wear out. Zinc, for example,
how do you replace it, since you no longer have any communication with
the surface world?
"Your question will have its answer", Captain Nemo responded, "I
will say to you, initially, that there exists on the sea-bed mines of
silver, iron, zinc, gold, whose exploitation would be doubtless
practicable. But I did not borrow anything from these metals of the
earth, and I wanted to take only from the sea itself the means of
producing my electricity."
"From the sea?"
"Yes, Professor, and I did not miss the means. I could, indeed, by
establishing a circuit between wires plunged to various depths, obtain
electricity by the difference in temperature; but I preferred to
employ a more practical system."
"Which is?"
"You know what sea-water is composed of. In a thousand grams are
found 96 1/2 per cent of water, and about 2 2/3 per cent of chloride
of sodium; then, in a smaller quantity, chlorides of magnesium and of
potassium, bromide of magnesium, sulfate of magnesia, sulfate and
carbonate of lime. You see, then, that chloride of sodium forms a
large part of it. So it is this sodium that I extract from the sea-
water, and of which I compose my ingredients.''
"Sodium?"
"Yes, sir. Mixed with mercury, it forms an amalgam that replaces
zinc in the Bunsen elements. The mercury never wears outs. Sodium
alone is consumed, and the sea itself provides it to me. I will say to
you, moreover, that the cells with sodium must be regarded as most
energetic, and that their electromotive force is double that of the
zinc cells."
"I understand well, Captain, the excellence of sodium under theses
conditions. The sea contains it. But it still must be manufactured,
extracted it in a word. And how do you do this? Your batteries could
obviously be used to power this extraction; but, if I am not mistaken,
the expenditure of sodium required by the electrical apparatus would
exceed the extracted quantity. You would consume more to produce it
than you would produce!"
"So, Professor, I do not extract it by the batteries, but quite
simply employ the heat of the pit coal."
"From the earth?" I insisted.
"Let us say 'coal of the sea', if you wish", answered Captain Nemo.
"And you can work underwater coal mines?"
"Mr Aronnax, you will see me do it. I ask you for an only little
patience, since you have time to be patient. I point out only this: I
owe all to the ocean; it produces electricity, and electricity gives
heat, light, motion, and, in a word, life to the Nautilus."

At the bottom was a fourth partition that separated this office
from the engine-room. A door opened, and I found myself in the
compartment where Captain Nemo--certainly an engineer of a very high
order--had arranged his locomotive machinery. This engine-room,
clearly lighted, did not measure less than sixty-five feet in length.
It was divided into two parts; the first contained the materials for
producing electricity, and the second the machinery that connected it
with the screw.
When we entered I was surprised by the unique odor that filled the
compartment. Captain Nemo noticed my surprise.
"It is," he told me, "a gas discharge produced by the use of
sodium; but it is only a minor inconvenience. Moreover, each morning
we purify the ship's atmosphere by ventilating it with fresh air."
I examined everything with great interest, in order to understand
the machinery of the Nautilus.
"You see," said the Captain, "I use Bunsen's contrivances, not
Ruhmkorff's. Those would not have been powerful enough. Bunsen's are
fewer in number, but strong and large, which experience proves to be
the best. The electricity produced passes aft, where it works, by
electro-magnets of great size, on a system of levers and cog-wheels
that transmit the movement to the to the axle of the screw. This one,
the diameter of which is nineteen feet, and the thread twenty- three
feet, performs about 120 revolutions in a second."
"And you get then?"
"A speed of fifty miles an hour."
There was a mystery here, but I did not insist on solving it. How
could electricity act with such power? Where did this almost unlimited
force come from? Was this enormous tension obtained by coils of a new
kind? Was its transmission enhanced by an unknown system of levers (1)
that could increase ad infinitum? This is what I could not understand.

another passage from the book

http://www.technovelgy.com/ct/content.asp?Bnum=639

and

Although Nemo never did describe Nautilus's engines in detail, but he
may have let the secret slip accidentally. At one point during M.
Arronax's stay, Nautilus refuels with sodium. If sodium mixes with
water, it generates heat, and then decomposes the water into oxygen
and hydrogen, which recombine violently. The reaction does not require
atmospheric oxygen, and could theoretically be used to power a
submarine.

Standard translations of 20TL omitted over 20-percent of the French
text, including important passages of technical detail, such as
Captain Nemo's explanation about the batteries used on the Nautilus
(Bunsen batteries, a type of wet primary cell actually used at the
time, but operating at higher voltage due to the replacement of zinc
with sodium in one electrode) and Professor Arronax's actual questions
to Nemo about the thermodynamics of his power source

"You see," said the Captain, "I use Bunsen's contrivances, not
Ruhmkorff's. Those would not have been powerful enough. Bunsens are
fewer in number, but strong and large, which experience proves to be
the best. The electricity produced passes forward, where it works, by
electro-magnets of great size, on a system of levers and cog-wheels
that transmit the movement to the axle of the screw. This one, the
diameter of which is 19-ft, and the thread 23-ft, performs about 120
revolutions in a second." And you get then? "A speed of 50 mph."

What did these contrivances consist of? Oddly enough, Verne eschewed
the rotary electric devices of his time. Already, in 1825, English
scientist Michael Faraday had established the principle of the
rotating motor, and an American blacksmith, Thomas Davenport, had
patented a direct-current (DC) motor with all its essentials -
rotating coils, a commutator, and brushes - in 1837. Yet, despite the
fact that several motor-driven electric vehicles had been demonstrated
in both Europe and America by the 1850s, Verne's theoretical pattern
for the prime mover on Nautilus turns out to be the electrical analog
of a reciprocating steam engine, "where large electromagnets actuate a
system of levers and gears that transmit the power to the propeller
shaft." So, in spite of the fact that only a rotating motor could
transmit the projected high torque required to twirl the massive
propeller at a sufficient speed to shoot the boat along at 45-kts, the
main engine seems to be mechanically equivalent to a steam engine with
"large electromagnets" replacing conventional pistons. This is an
option that seems peculiarly conservative in light of Verne's
technological erudition.

In contrast, the "breakthrough" that enables Nemo to generate
virtually unlimited electrical power extrapolates electrical science
so far into the future that only the willing suspension of disbelief
keeps technically-astute readers onboard. Thus, although, as noted
above, some impulsive commentators have mistakenly represented
Nautilus as "nuclear-powered," the actual source for her vast reserves
of electricity is described as a hugely scaled-up amplification of a
well-known 19th-century primary battery, the Bunsen cell. Invented in
1841 by German physicist Robert Bunsen - better known for devising the
Bunsen burner - the Bunsen cell uses a carbon cathode in nitric acid
and a zinc anode in dilute sulfuric acid, with a porous separator
between the liquids. The device generates a potential of 1.89v, and
later versions added potassium dichromate as a depolarizer. Here is
Captain Nemo describing his fundamental modification:

et.seq.
http://findarticles.com/p/articles/mi_qa4442/is_200606/ai_n17177267/pg_5?tag=artBody;col1
.

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