“20000 Leagues Under the Sea” Part2 Ch01

Question 1: Was Captain Nemo more of a Hermit or a Terrorist?  Consider the following quote from Part2 Ch1 when answering this question:

I could no longer content myself with the hypothesis which satisfied Conseil.

That worthy fellow persisted in seeing in the commander of the Nautilus one of those unknown savants who return mankind contempt for indifference.  For him, he was a misunderstood genius, who, tired of earth’s deceptions, had taken refuge in this inaccessible medium, where he might follow his instincts freely.  To my mind, this hypothesis explained but one side of Captain Nemo’s character.

Indeed, the mystery of that last night, during which we had been chained in prison, the sleep, and the precaution so violently taken by the Captain of snatching from my eyes the glass I had raised to sweep the horizon, the mortal wound of the man, due to an unaccountable shock of the Nautilus, all put me on a new track.  No; Captain Nemo was not satisfied with shunning man. His formidible apparatus not only suited his instinct of freedom, but, perhaps, also the design of some terrible retaliation.

Question 2: The arc lamp used as the great lantern of the Nautilus operated in a vacuum and its graphite points wasted imperceptibly.  How does an arc lamp work?  Do they really work in a vacuum?  And what rate do the points of an arc lamp ordinarily break down?

Answer 2: Arc lamps historically haven’t worked in a vacuum.  In pgs. 481-482 of Audel’s Handy Book of Practical Electricity with Wiring Diagrams by Frank D. Graham (published by Theo. Audel & Co., 49 W. 23rd St., New York, U.S.A, copyright 1942) it mentions enclosed arcs where the arc is enclosed in glass bulbs, but makes no mention of those bulbs being devoid of air.  It states of the enclosed arcs:

The enclosed arc is the result of various attempts to reduce the rapid consumption of the carbons in the case of open arc, by enclosing the arc in a globe bulb of refractory glass protected by a large outer globe.

As to the life of such enclosed carbon electrodes, it states that enclosed carbon alternating current arcs have an electrode life of 100-125 hours.  The arc is about 3/8 inches long and requires 70 to 80 volts.  The electrode ends are nearly flat (because the current is a.c. as opposed to d.c.).  If direct current (d.c.) is used then the positive electrode has a characteristic crater and is consumed twice as fast as the negative electrode.  As to how the electric arc lamp works, this same book gives the following description:

The Electric Arc. — If two carbon rods be connected electrically to the terminals of a dynamo and the free ends of the rods brought together, the current from the dynamo will flow through the closed circuit thus established.  Now, if the carbon rods be drawn apart so as to form a slight break of one-eighth of an inch or less in the circuit, the current will jump from one rod to the other and the arc thus formed will be maintained across the gap in the circuit, by the conductivity of a bridge of carbon vapor allowing a continuance of current. 

Either d.c. or a.c. may be used, but the two carbon rods must be first brought into contact with each other and then separated in order to establish the arc, otherwise a pressure of several thousand volts would be required to make the current jump the air gap.

The arc usually consumes 10 amperes at 45 volts or 450 watts; its temperature is about 6,300 degrees Fahrenheit.

In order to maintain a constant arc length as the electrodes burn away, there are various carbon rod feed mechanisms, the simplest being a solenoid attached to the upper electrode that works as states on pg 482 of the same book:

In operation, gravity tends to keep the carbons in contact while the pull of the solenoid tends to keep them apart.  Equilibrium is established between these two opposing forces because of the weakening of the solenoid pull due to increased resistance interposed as the upper carbon is drawn away from the lower or fixed carbon.  The weight of the carbon and plunger, or the ampere turns on the solenoid must be so adjusted that an arc of proper length is established when equilibrium is reached.

Question 3: Do sea birds rest upon the waves when fatigued?  How do they keep their wings dry enough to fly with after resting upon the waves?

Question 4: What are the pectoral fins on a fish?

Answer 4: The pectoral fins on a fish are analogous to flippers on a dolphin, attached to the breast.

Question 5: Do modern submarines use inclined planes to vary their depth as they travel through the water?

Question 6: Do molluscs move by jet propulsion?

Question 7: Do Indians still float their dead on the Ganges River out to sea?

Question 8: Is there really such a thing as a milk sea?  What other changes in sea water color are due to biological organisms?

Question 9: How are the fish of the family Ostraciontidae like the tortoise?

Answer 9: Like the tortoise, these related species of fish have body armour.  Also known as trunkfish, these fish live among the corals in the bottom regions of warm tropical waters around the world.  They have bodies fully protected except on the tail by a box made of walls of closely fitting six-sided bony plates.  This box is flat bottomed and either 3,4 or 5 sided in cross-section. 

They bite off chunks of coral in order to eat the coral polyps and other small invertebrates within.

(information from pgs 238-241 of “Encyclopedia of Fish” by Maurice and Robert Burton, Copyright 1970, BPC Publishing Ltd.)

Question 10: What are tunnies?

Answer 10: Tunnies is the plural form of “tunny” or bluefin tuna of the Atlantic.  They can grow up to 14 feet long and weigh up to 1800 pounds, however only smaller specimens make up shoals of similar sized tuna.  Their migrations are often dependent upon the migrations of their prey and seasonal water temperatures.  Tuna swim almost continuously at speeds of up to 50 mph, with their mouths slightly open in order to supply enough oxygen via water movement across their gills.

(information from pgs 242-243 of “Encyclopedia of Fish” by Maurice and Robert Burton, Copyright 1970, BPC Publishing Ltd.)


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