“20000 Leagues Under the Sea” Part1 Ch14

Question 1: What was the Rouquayrol apparatus? 

Answer 1: In Volume 12 “Man Reenters the Sea” of “The Ocean World of Jacques Cousteau” series of books, copyright 1975 by Jacques-Yves Cousteau published by The Dansbury Press it explains the Rouquayrol apparatus:


In 1869, Jules Verne’s Twenty Thousand Leagues Under the Sea foresaw at least a two-dimensional freedom of men reentering the sea. Captain Nemo, skipper of the submarine Nautilus, remarks to Professor Aronnax, “You know as well as I do, Professor, that man can live under water providing he carries a sufficient supply of breathable air.”

But already in Verne’s time, practical steps were being made toward freedom.  Four years before the publication of Verne’s classic, Benoit Rouquayrol and Auguste Denayrouze unveiled a device which allowed a diver to store a small amount of compressed air on his back, disconnect his air hose to the surface, and walk free on the floor of the ocean.  The freedom was short-lived and the apparatus primitive, but those first steps had been taken in 1865.  The key to the Rouquayrol-Denayrouze device was a regulator which helped control the flow of air from the underwater reservoir to the diver’s mouth.

Question 2: How many psi is 50 atmospheres?

Answer 2: 50 atmospheres = 735psi

Question 3: Captain Nemo’s diving apparatus stored enough air for 9-10 hours of diving.  How long can modern scuba divers stay underwater with their air tanks?

Answer 3:  In Volume 12 “Man Reenters the Sea” of “The Ocean World of Jacques Cousteau” series of books, copyright 1975 by Jacques-Yves Cousteau published by The Dansbury Press it mentions typical time limits of air tanks depending on diving depth:

pg 104:

The conventional open-circuit, self-contained compressed-air breathing apparatus has opened the world of the sea to millions of people.  Of all the breathing devices available it is by far the easiest and safest for the novice diver to use.  But in addition to the restrictions imposed by oxygen and nitrogen in a compressed-air system, there are limitations in the device itself.  It is bulky, and out of water it is quite heavy – about 50 pounds.  The valve that releases air from the compressed-air cylinder operates noisily underwater, where sound is conducted much better than in air, and the exhalations of the diver are not only noisy, but the bubbles are conspicuous enough to frighten some marine creatures.  And because of the open circuit, a large volume of gas is used in relatively short periods when the diver is at great depths.  A big two-tank unit is good for nearly two hours of work at 30 feet, but less than 30 minutes of light work at 200 feet, excluding decompression time, which for such a dive would total an hour and a half.

To extend the capability beyond that of the open-circuit breathing apparatus, it would be necessary to recycle the neutral gas, since it is not contaminated and does not need to be vented.  Oxygen must be provided at a partial pressure of between 20 percent and 40 percent of one atmosphere.  Exhaled carbon dioxide must be removed from the system in order to keep the diver healthy.

Question 4: How far can you shoot a bullet under water?

Answer 4: Not very far.  Tests done shooting from air straight into water typically slow down to nonlethal speeds as the bullet passes the 8 feet depth.  Furthermore, high velocity rounds, e.g. hollow point bullets often disintegrate when they hit water after being shot from air.  See: http://wiki.answers.com/Q/How_far_would_a_bullet_penetrate_water_before_it_stops_in_water.

Question 5: How dense is water compared to air?  Is it 855 times denser?

Answer 5: The density of water changes very little with depth while air’s density depends greatly on temperature and pressure due to elevation.  At sea level and at 20 degrees Celsius air is about 800 times less dense than water at sea level.  See http://en.wikipedia.org/wiki/Density_of_air.

Question 6: Are there bullets today that incapacitate or kill via electricity?

Answer 6: There are non-lethal shock-bullets available.  See: http://www.impactlab.com/2004/02/26/announcing-non-lethal-electric-bullets/.

Question 7: Can one make paper from the zostera marina?

Answer 7: According to the following website about Eelgrass (zostera marina) found off the Washington State coast: 


Eelgrass has historically been used for a variety of human needs such as food, basket weaving, compost, bedding, insulation and high-grade paper. 

It also mentions where eelgrass can be found:

Eelgrass grows in the muddy or sandy substrate of the shallow sub-tidal zone, down to a depth of approximately 22 feet in the Northwest. Eelgrass grows throughout the Puget Sound, the Pacific and Atlantic Coasts, and in Europe. 

Question 8: 

By degrees the fog disappeared under the action of the sun’s rays, the radiant orb rose from behind the eastern horizon.  The sea flamed under its glance like a train of gunpowder.  The clouds scattered in the heights were coloured with lively tints of beautiful shades, and numerous “mares tails,” which betokened wind for that day.  But what was wind to this Nautilus which tempests could not frighten!”

What literary tools does Jules Verne use here to paint such a rich picture of the play of the sun, ocean and wind at sunrise.  Does he use metaphore and simile?

Answer 8: Paraphrasing the Encarta Dictionary, the first definition of the word metaphor is: 

an implicit comparison used to describe someone or something using figurative expressions, e.g. saying that somebody is a snake (which could imply that they are slithering, sneaky, and/or evil).

A simile is defined by the same dictionary as:

a figure of speech that draws a comparison between two different things, especially a phrase containing the word “like” or “as,” e.g. “as white as a sheet”

Question 9: How long does it take the sun to rise by its own height above the horizon?  How does this compare to the moon rising by its own height above the horizon?

Answer 9: You can get the time of the next sunrise at the website:


Then measure how long it takes for the sun or moon to be completely above the horizon after they first break above it.  CAUTION: Be sure not to stare directly at the sun since this will damage your eyes!

Question 10: Is there really an Island of Crespo at 32 degrees 40 minutes North Latitude and 157 degrees 50 minutes West Longitude?  According to “20000 Leagues Under the Sea” this island was marked in ancient Spanish maps as Rocca de la Plata, “The Silver Rock”.

Answer 10: We could convert the degrees, minutes, seconds version of latitude,longitude to an equivalent decimal form using the online calculator at the website:


Then we can use google maps to search for this location (32.6667,-157.8333), e.g.:


Note: This location is in open sea about 700-800 miles North of the Hawaiian islands.

Question 11: Nemo’s divers using the Rouquayrol apparatus had air tanks under a pressure of 50 atmospheres.  How much pressure is in a scuba diver’s air tanks?

Answer 11: According to the website:


the pressure of scuba tanks can vary between 2400 psi and 3440 psi.  Air tanks can be aluminum or steel.  Steel tanks can be low pressure or high pressure.  High pressure tanks require a different kind of valve than the lower pressure ones.  Since 1 atmosphere = 14.7 psi at sea level, 50 atmospheres is 50 times this or 735 psi.  So Captain Nemo’s scuba tanks were only about a third of the pressure of modern low-pressure scuba air tanks.

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