Undersea Warfare The Official Magazine of the U.S. Submarine Force. Winter 2004 U.S. Submarines... Because Stealth Matters Cover for Winter 2004
On the Cover
Masthead
Submit Feedback
Submit An Article
Departments
Washington Watch
Downlink
Operational Depth. No article this issue.
Ships At Sea
Letters to the Editor. No article this issue.
Features

From Humble Origins
China’s Submarine Force Comes of Age

Submarine Force Links
Undersea Warfare Photo Contest
 
 
Undersea Warfare 2002 CHINFO Merit Award

Electricity – A “Powerful Agent”

With its imaginative technology, Nemo’s engineering plant for Nautilus is certainly the most extraordinary aspect of his design. On behalf of his nautical protagonist, Verne conceived what was essentially an “all-electric” ship at a time when the first practical applications of electricity were only a few decades old and a century before building any such ships became feasible. In Captain Nemo’s oft-quoted words,

 
Illustrations caption follows
Nautilus is powered entirely with electricity produced from the sodium found in seawater by scaled-up and modified “Bunsen cells.” This original engraving of Captain Nemo and Professor Aronnax inspecting the engine room seems to show large Bunsen cells to the right and a huge “Ruhmkorff coil” for stepping up the voltage overhead.

There is a powerful agent, obedient, rapid, facile, which can be put to any use and reigns supreme on board my ship. It does everything. It illuminates our ship, it warms us, it is the soul of our mechanical apparatus. This agent is – electricity.

And indeed, Nautilus uses electricity for cooking, lighting, distilling fresh water, running pumps and other auxiliaries, instrumentation, and, of course, main propulsion. The ship is fitted with a conventional four-bladed propeller at the stern, six meters (20 feet) in diameter and coaxial with the centerline of the hull. Consistent with the relative diameters of the hull and propeller and the freeboard prescribed by Captain Nemo, Aronnax observes that when surfaced, the propeller blades occasionally rise above the waves, “beating the water with mathematical precision.” Verne has Nemo claiming a speed of 50 knots at 120 revolutions per second – probably in error. 120 revolutions per minute makes much more engineering sense for a propeller that size, particularly in view of the type of engine that powers the submarine.

Curiously, the main propulsion engine on Nautilus is not a rotating electric motor. English scientist Michael Faraday (1791-1867) had established the principle of the rotating motor by 1825, 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 mid-century, Verne’s notional design for the prime mover on Nautilus emerges as 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.” In other words, the main engine seems to be mechanically equivalent to a steam engine with “large electromagnets” replacing conventional pistons – a choice that seems strangely backward-looking in light of Verne’s technical sophistication.

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. Although some hasty writers have wrongly portrayed Nautilus as “nuclear-powered,” the actual source for her vast reserves of electricity is described as a hugely scaled-up elaboration of a well-known 19th-century primary battery, the Bunsen cell. Invented in 1841 by German physicist Robert Bunsen (1811-1899) – 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 1.89 volts, and later versions added potassium dichromate as a depolarizer.6 Let Captain Nemo describe his fundamental modification:

Mixed with mercury, sodium forms an amalgam that takes the place of zinc in Bunsen batteries. The mercury is never consumed, only the sodium is used up, and the sea resupplies me with that. Moreover, I can tell you, sodium batteries are more powerful. Their electric motive [sic] force is twice that of zinc batteries.

Had this actually been tried, the reaction of metallic sodium with sulfuric acid would have been exciting to behold.

Despite some ambiguity in Verne’s description, it also appears that the relatively low voltage of the Bunsen cells is stepped up to a more useful level using a double-wound variant of the induction (i.e., “spark”) coil invented in Paris by another German, Heinrich Ruhmkorff (1803-1877), around 1850.7 This same combination of a sodium-based Bunsen cell, probably some kind of periodic interrupter, and a Ruhmkorff coil is described later in the novel as a high-voltage power source for portable undersea lights. Ultimately, Nemo replenishes his sodium supply by distilling seawater and separating out its mineral components at a secret operating base located inside the crater of a volcanic island near the Canary Islands. The energy for this process is derived by burning sea coal, which he and his men mine from the ocean bottom.

Drawing caption follows
The most advanced French submersible built prior to the publication of Twenty Thousand Leagues Under the Sea was Bourgeois and Brun’s Le Plongeur, launched in 1863. Powered by stored compressed air, the 140-foot craft achieved five knots submerged, but inadequate longitudinal stability forced its abandonment by the French Navy after three years of experiments.

Submerging, Surfacing, and Life Onboard

Similar to the approach adopted by subsequent submarine pioneers Simon Lake and Thorsten Nordenfeldt, the basic technique described for submerging Nautilus and maintaining a desired operating depth is to flood ballast tanks to establish net neutral buoyancy at the corresponding water density. The main ballast tanks are sized to bring the boat just under the surface when completely filled. For deeper submergence, additional water is introduced into supplementary tanks, which can increase the weight of the submarine by as much as 100 metric tons to match the increasing weight of its displacement with depth. As John Holland later established in his first successful submarine designs, a much more efficient depth-control technique is to establish slightly positive buoyancy and maintain depth using the dynamic forces generated by the boat’s forward speed. In fact, “with a view to saving [his] engines,” Captain Nemo also exploits dynamic forces, but only when he wants to take Nautilus below 2,000 meters. Then, two horizontal hydroplanes mounted at the center of flotation (that is, amidships) are used to angle the boat downward in response to the thrust of the propeller. Within a few decades of the appearance of Twenty Thousand Leagues Under the Sea, it had also been realized that stern planes are much more efficient for controlling depth dynamically, but Nautilus has no stern planes. In any event, Verne claims extreme depth capabilities for Nautilus – Aronnax reports reaching a depth of 16,000 meters (52,500 feet) in the South Atlantic – reflecting a time when it was not yet known that the world ocean reaches a maximum depth of nearly 36,000 feet in the Challenger Deep.

To regain the surface, the ballast tanks are emptied – not by compressed air, but rather by using powerful electric pumps, supposedly capable of working against even the highest back-pressure. Aronnax even describes what we would call today an “emergency surface blow”:

The Nautilus rose with terrific speed, like a balloon shooting into the sky. Vibrating sonorously, it knifed up through those waters. We could see nothing at all. In four minutes we traveled those four leagues between the bottom and the surface.8 After emerging into the air like a flying fish, the Nautilus fell back into the water, making it leap like a fountain to a prodigious height.

Although Nemo acknowledges that he has the scientific acumen to “manufacture” air for ventilating the submarine underwater, he opts instead to use electrically-driven compressors to store breathing air in special tanks, with periodic visits to the surface to replenish his supply. However, when Nautilus becomes wedged beneath an ice cap near the South Pole – another geographical misapprehension – this dependence on surface air puts the crew in extremis until they devise a clever way to free the boat by melting the surrounding ice – using electricity, of course.

Nemo’s crew are a strange, largely silent lot, and it’s never clear how many there are. The most Aronnax ever sees on deck at one time are about 20, but there are likely more below. However,
the crew’s berthing compartment on Nautilus is only 5 meters (16 feet) long, so unless the berths are stacked like cordwood – or there’s a lot of hot-bunking going on – it seems unlikely
that there could be more than 40. On the other hand, Captain Nemo’s quarters are quite lavish, consisting of a 5-meter bedroom, a 5-meter private dining room, a library of about the same size, and a 10-meter salon – 25 meters out of a total hull length of 70 meters. Moreover, the salon contains a priceless collection of European art, a small museum of unique biological specimens, and most famously, a pipe organ. Large observation windows, concealed by movable panels, are fitted into the outboard bulkheads, providing a close-up view of the passing underwater scene to both sides, illuminated as necessary by the external searchlight.

Nautilus as a Warship

Illustration caption follows
In his novel, Verne describes bottom excursions from Nautilus with passengers and crew clad in diving suits that accurately prefigure today’s SCUBA gear. Sustained by stored compressed air, assisted by powerful electric torches, and protected by air-powered small arms firing electric “bullets,” Verne’s undersea explorers opened the beauty and mystery of the deep to millions of armchair readers.

In its role as a combatant, Nautilus functions primarily as a high-speed ram, and for this purpose, its bow narrows finely to a reinforced steel point, triangular in cross section. In one harrowing chapter, Professor Aronnax describes its effectiveness in destroying a warship – presumably British – from initial detection and sparring for position; through “clearing for action” by retracting the pilothouse and searchlight to produce a smooth, projectile-like shape; diving the boat; running up to speed on a broadside collision course; and passing right through the victim “like a sailmaker’s needle through canvas!” There are no survivors.

From its encounter with Abraham Lincoln, we can also deduce that the submarine’s powerful ballast pumps can also be used as water cannon when “non-lethal force” is called for, but except for a substantial arsenal of unique small arms, Nautilus carries no other weapons. Nemo and his crew use highly advanced air rifles for hunting and self-defense both on land and underwater. These versatile guns are charged from portable compressed air tanks but instead of shooting conventional solid bullets, they launch small glass capsules,

…which are sheathed in steel and weighted with lead. They are veritable little Leyden jars charged with high-voltage electricity. At the slightest impact they discharge, and the animal, no matter how large or strong, falls dead.

Unfortunately, this novel technique of shooting what amounts to charged capacitors as bullets falls short in Nautilus’s celebrated encounter with a school of giant squid, because the projectiles pass right through the animals’ soft bodies without activating. Thus, Nemo’s crew and their “passengers” are reduced to hand-to-hand combat with the monsters, but that only makes for a more exciting story in which Ned Land can exhibit his prowess with the harpoon.

Captain Nemo as Scientist and Explorer

For underwater exploration, treasure-hunting, and gathering food from the ocean bottom, Captain Nemo has provided Nautilus with an integrated airlock and a suite of sophisticated diving equipment, which includes diving suits with a self-contained underwater breathing capability clearly recognizable in today’s SCUBA gear. Nemo credits the Rouquayrol-Denayrouze diving apparatus – a “demand-valve” system invented in France in 1864 – as the basis for his version, which uses back-packed tanks of highly-compressed air capable of sustaining underwater excursions ten hours long. For undersea illumination, spiral gas-discharge tubes – actually invented earlier in the century – are used as lanterns, with excitation by the high-voltage output of a portable version of the Bunsen-Ruhmkorff system described above.9 Outfitted in this way, Professor Aronnax, Conseil, and Ned Land join Nemo and his men for a series of vividly-depicted underwater expeditions, where they get to experience both the wonders and dangers of the deep.

Despite Nemo’s obsessive, vengeance-driven dark side, Verne credits him with unparalleled accomplishments as an underwater scientist and explorer. Among his many discoveries are the lost continent of Atlantis, a subterranean passage between the Red Sea and the Mediter-ranean (i.e., a subaqueous Suez Canal), countless new species of undersea life, and new findings in oceanography. He maps the ocean bottom, measures thermal profiles, and observes that in all the deeps of the world, the water temperature approaches the same limiting value of 4.5 degrees Centigrade. He skillfully conns Nautilus through the Strait of Gibraltar by taking advantage of the same deep-lying, outward-flowing current layer exploited by savvy submariners in two world wars decades later. In the wonderful world of Twenty Thousand Leagues, there is seemingly nothing that Captain Nemo cannot do.

The Undersea Legacy of Jules Verne

Accelerating progress in fielding undersea vehicles in the late 19th century – and rapid advances in both natural science and engineering technology – created the milieu within which Verne launched his “submarine novel.” For a non-specialist, Verne was unusually well-informed about recent progress in the science and technology of his times. Consequently, his reputation as a futurist rests not only on his imaginative predictions of things to come, but also on his uncanny skill in crafting convincing extrapolations of the technologies of his era to achieve those visions. Flying continental distances, journeying to the moon, penetrating to the center of the earth, exploring the depths of the ocean at will – all these had been thought of by other men. But it was Jules Verne who first popularized notional solutions to these challenges and created a sense of possibility that had been absent before.

So alive does Nemo become for us in Twenty Thousand Leagues Under the Sea that generations of readers have been tempted to credit him with creating Nautilus and stimulating our subsequent fascination with the undersea world. But it is really the broad erudition – and extraordinary imagination – of Jules Verne that illuminate these pages, much as Nemo’s Ruhmkorff lights illuminated the treasures of the deep. Verne died in 1905, just as the first generation of modern submarines reached fruition and less than a decade before they achieved their first lethal successes in undersea warfare. In foreseeing the possibilities inherent in the submarine 35 years before, he had been right about some things and wrong about others, but the likelihood of fulfilling all the essentials of his vision is now little doubted.


Authors note: The best modern translation of Twenty Thousand Leagues Under the Sea is that of Walter James Miller and Frederick Paul Walter (Naval Institute Press, Annapolis, 1993). This version restores all of the French text customarily deleted in earlier English translations, and it includes many helpful annotations. Another useful source of information on the technical details of Nautilus, as well as a fascinating survey of past and present represen-tations, is the website of Michael and Karen Crisafulli, http://home.att.net/~karen.crisafulli/nautilus.html.


Notes

1 That same year, the Franco-Prussian War broke out – much to France’s ultimate disadvantage – and Verne served briefly as commanding officer of a small coast guard vessel at Le Crotoy near the mouth of the Somme. Reportedly, during that period he wrote the drafts of four novels!

2 By Verne’s reckoning, 20,000 leagues is about 43,000 nautical miles.

3 In a subsequent Jules Verne novel, The Mysterious Island (1875), Captain Nemo reappears near the end of his life, he and Nautilus having survived their encounter with the Maelstrom to continue their underwater quest. It emerges that Nemo was born Prince Dakkar, an Indian rajah’s son of extraordinary intellect, who was provided a comprehensive education in Europe, where he developed unparalleled artistic and scientific capabilities. After he returned to India, Prince Dakkar became a leader of the gathering independence movement that erupted in the “Great Indian Mutiny” of 1857, which was brutally suppressed by the British. Although Dakkar’s family was massacred in the upheaval, he himself escaped, gathered an international band of what might be called today “freedom fighters,” and built Nautilus in secret as an instrument of vengeance against oppression world-wide – and particularly against the British.

4 Professor Aronnax contradicts himself in describing Nautilus’s hull plating. When first stranded on top, he notes, “That blackish back on which I was sitting was glossy and smooth, with nothing like overlapping scales.” Some days later, he says, “I noticed that its iron plates, slightly overlapping each other, resembled the scales covering the bodies of large terrestrial reptiles.” Moreover, the hull is described as iron in one passage and steel in another.

5 In size and shape, Nautilus is similar to the former experimental submarine USS Albacore (AGSS-569) launched in 1953: 203 feet long, 1,242 tons surfaced, 1,847 submerged. However, in comparing the ratio of surface to underwater displacement, Nautilus more closely approximates subsequent nuclear-powered attack submarines, such as the USS Los Angeles (SSN-688) class.

6 Interestingly, an electric boat powered by a Bunsen-cell pile was apparently demonstrated in Paris in 1871.

7 At one point, Verne refers to “Ruhmkorff cells,” but this is probably an error.

8 Covering four vertical leagues in four minutes corresponds to an average rate of rise of 130 knots – hardly likely!

9 An inconsistency appears in Captain Nemo’s description of his portable light source. There he speaks of “a Bunsen battery that I activate not with potassium dichromate but with sodium.” Previously, he described replacing the Bunsen cell’s zinc elements with sodium. Interestingly, Verne had already prognosticated such “Ruhmkorff lights” in Journey to the Center of the Earth and From the Earth to the Moon.