The outcome of the great war that is now being waged in Europe hinges largely on the ability of the Central Powers[1] to sink the ships of the Allies[2] by means of submarines, and of the Allies to destroy the enemy U-boats,[3] as the German submarines are commonly called.

Now, while a U-boat is a submarine, all submarines are not U-boats; for the word submarine means any and everything that lives, is done, or works beneath the surface of the sea. Thus, a fish is a submarine, and so is a boy while he is under water—though his clothes may be on the shore.

How the Submarine Came to Be.—Yes, the fish of the Paleozoic[4] era, see Fig. 1, was the earliest submarine, in that it moved in and through the water under its own power, and that was millions of years before the human race and the monkey tribe branched off from a common ancestor.

Not only has the shape of the fish—or ichthyoid form, as it is called—served as a model for inventors of the submarine boat to go by, but the air-bladder in the fish, which aids it in keeping its place below the surface of the water, finds its counterpart in the ballast tanks of the modern submarine.

When the first real boy parted from his monkey cousin—that is, when the boy came down from his tree-top house and left the monkey up there to eat a banana all alone—Nature had fitted him with long legs and flat feet so that he might swiftly run away from his enemies on land.

But in those days when the earth was young there were not only gigantic, long-necked animals with cross-cut saw tails and cunning little heads, but terrifying winged lizards[5] flew around everywhere like airplanes do now, and monstrous and inconceivable things swam in the sea. He could easily outwit and outdistance his animal foes on land, but he could not fly away from those that sailed the air, nor could he venture far into the water for fear of his aquatic enemies. But he learned to swim in spite of them and when he could dive down here and come up over there he became the second submarine. (See Fig. 2.)

From the time he learned to swim and grew to be a man he nursed the idea of making some kind of device that he could get into and swim about with, not only so that he might be protected from the monsters that sought him as food but that he might destroy them as well.

And even after all the prehistoric beasts became extinct and so were no more on the face of the earth to menace his safety, he still kept thinking over the idea of the submarine, and it kept getting stronger within him as the convolutions of his brain grew deeper.

The Development of the Submarine.—By hard thinking and long experimenting, and the other way about, and always working to the end that he might invent some kind of boat by which he could travel under and through the water (or, as the French have it, sous marin—sous meaning under and, of course marin means sea) like the swiftest of fish and quite as easily.

His reason for wanting a submarine boat now that the animals he had so feared in the past had disappeared, was to find treasure ships that had sunk to the bottom of the old ocean, or, more likely because it seemed more practical, to attack, unseen and without warning, merchantmen that carried precious cargoes—in a word, he would a submarine pirate be.

But like everything else that needs mechanical devices and electrical apparatus the development of the submarine from the first crude attempts to the powerful and perfectly controlled U-boat as we know it to our sorrow to-day took many men working through many years to make it sea-worthy and practical.

In each one of these inventors the thought that ruled him was to make a boat which would sink or swim, as he wanted it to; and though none of the earlier workers succeeded in building a really good submarine, it was not their fault but their misfortune, for the vital mechanical and electrical appliances they needed had yet to be invented.

But the efforts of each one of these pioneers served as a stepping-stone to the building of the first practical boat, in 1901, which could be used successfully as an undersea destroyer. This was the Holland, which you will read more about presently; and the British Admiralty purchased five of the first ones built.

The First Submarine Boat.—Away back there in the very year when the Pilgrims landed from the Mayflower on Plymouth Rock—that is to say, in 1620—a Dutchman named Van Drebel, who happened to be living at that time in England, worked out the idea that originated in the brain of his prehistoric ancestor, and that was to build a submarine boat.

Of course in those days there were no such things as steel boats, nor had engines to propel them been invented, but men were adept builders of wooden boats and, as much or more to their credit, they were past masters of the art of sailing them.

But the lack of steel, of engines, and of other recent inventions didn’t daunt the dauntless Van Drebel in the least; for he went right ahead and built his underwater craft of such materials as he could get hold of. His submarine was nothing more nor less than a regular wooden boat which was completely decked over, covered with leather, and smeared with tallow to make it watertight.

The submarine was propelled through the water by means of a pair of oars on each side as shown in Fig. 3, very much in the same fashion as were the far-famed Grecian galleys of old; but in this boat the oars passed through watertight flexible covers fastened over the portholes.

A hollow mast was stepped into the deck to supply air to the crew when the submarine was under water, and it was also used to spread a little canvas on when the boat was running afloat and the wind was good.

Now, you may think this submarine of Van Drebel’s was a mighty crude attempt, and no one will say you nay, but just bear in mind, please, that it was the granddaddy of the modern submarine and that it traveled submerged down the Thames River, carrying in it no less a personage than King James the First, and covering a distance of seven miles from Westminster to Greenwich.

After this first and very successful attempt at submarine building it was not long until others began to make improvements and to build underwater boats which would outdo the spectacular performance of Van Drebel’s submarine. It ought to send a thrill of pleasure through you to know that most of these inventors were Americans, but in your feeling of pride don’t forget that the oversea workers along submarine lines followed closely on the heels of our own in ingenuity, building, and operative ability.

A Submarine of the Revolution.—The first submarine designed to destroy enemy ships was invented and built by an American named David Bushnell, just about the time that Liberty Bell was ringing out the Independence of the United States.

His submarine, had it not been for an accident, and of which I will tell you later, would now be exploited in every school history of our country. But even the accident showed that the submarine had great inherent possibilities and dynamic power stored up in it which warring nations of the future must reckon with.

Different from all past ideas and present conceptions of submarines, and far removed from any design which is ordinarily thought of in connection with boats, Bushnell’s submarine, instead of going through the water with its long axis horizontal to the top, moved through it vertically.

The way in which this strange craft was submerged—that is, sunk—is fundamental, which means that it is the simple, natural way and the one that is used in all submarines that have been built since then.

A number of empty tanks were so fixed in the vessel that when the pilot wanted to submerge it he could let the water into them, and when he wanted to rise to the surface again he could pump the water out with a hand force-pump. This scheme is used in all of the submarine boats of the present time, though of course the pumps are power-driven.

A heavy weight that could be detached was fixed to the bottom of the craft, which helped it to maintain its upright position and also aided in submerging it. In case an accident happened to the pumps the weight could be released, when the craft would come to the surface.

Another good feature of this submarine was the valves which let fresh air into the vessel when it floated on top of the water but which closed automatically—that is, without the help of the pilot—when the submarine sank below the water line.

The way the first submarine of Bushnells was driven was just as primitive as the one built by Van Drebel; indeed, it was a shade worse, for a solitary oar sticking through the rear end of the shell provided the means for going ahead while another oar on one side helped to raise and lower it.

He later designed, built, and successfully operated another submarine, which was far superior to his first model. It had the same shape as his first one but it was propelled by two screws which were turned by hand; one of these moved the submarine forward and backward through the water, and the other one moved it up and down—all of which is clearly shown in Fig. 4. Hence the credit for the invention of the screw-driven submarine belongs to Bushnell.

The First Torpedo Fired by a Submarine.—Bushnell, though, did more than to invent a workable submarine, for he also devised and used a torpedo; or it would be better to call it a bomb, since it was timed to explode by clock-work, instead of by concussion. He intended to hang this submarine bomb on the bottom of an enemy ship—and thereby hangs a tale.

The British man-of-war Eagle had anchored in New York Harbor close to Staten Island sometime in the famous year of 1776.

The inventor was a patriot and offered his services and the use of his submarine to the new United States Government; the latter accepted them and ordered him to blow up the warship. As the inventor became sick he gave a sergeant, named Lee, the honor of using his submarine and blowing up the ship. Lee worked the submarine without a hitch until he reached the man-of-war, and then his troubles began.

Try as he would, he could not drive the screw into the tough English oak of which the hull of the ship was made, and this he must needs do in order to fasten the bomb to the bottom of it.

Finally, just as the clock-work of the torpedo was about to explode it, he set it adrift, and the young officer made off just in time to save himself. As it was, the bomb exploded close to the stern of the boat, but it did not do any serious damage.

Robert Fulton’s Submarine.—About the year 1800, Robert Fulton, the Famous American inventor, who built the first successful steamboat, designed and built a submarine that was far ahead of either of those I have just described.

It was cigar-shaped, to begin with, and this lessened the resistance it offered to the water, and it was fitted with a keel, a rudder, a propeller, and a conning tower, so that the pilot could see where he was going. Fulton did not attempt, though, to use a steam engine to drive the propeller, but turned it by hand. His submarine is shown in Fig. 5.

Another big improvement that Fulton made was to cover the hull of his submarine with copper plates. Taken altogether it came as near being a real submarine as could have been made with the materials and inventions which were available at that time.

After offering his submarine to the French, British, and American Governments in turn, and after it was turned down by all of them because they failed to see in it a useful weapon of war, Fulton turned his thoughts toward home and craft of a more peaceful nature.

Had any one of these governments been able to see the wonderful possibilities of the undersea craft that Fulton had so greatly improved upon, the submarine would have been perfected long before it was.

Fulton’s remarkable experiment, with his Nautilus, as he called his boat, on the Seine River, which flows through Paris, attracted much attention, and a plan was set on foot to use his submarine to rescue the exiled Napoleon from the Island of St. Helena. Again Fulton was doomed to disappointment, for the Great Emperor died before the scheme could be carried out.

It was then that Fulton returned to the United States and set about the more peaceful task of building a steam propelled river boat, or steam boat as it is called, and which won for him much money and undying fame.

The Earliest Steam Propelled Submarine.—It was eighty years after Fulton made his classic underwater experiments that Garrett, an English inventor, designed, built, and operated a submarine which used steam as its source of power.

This later submarine had all the good features of Fulton’s craft, besides the history-making improvement of using a steam engine to drive her—not only when she was afloat but when she was submerged as well.

The way it was done was like this: a regular boiler was set in the boat and this had a telescopic funnel, as a ship’s smoke-stack is called. When running on the surface the water in the boiler was changed into steam and the smoke poured out of the funnel. But when the craft was submerged, the funnel was drawn under the deck, the fire doors, which were made air tight, were closed, and the steam pressure already generated in the boiler was high enough to run the boat for several miles.

The Coming of the Torpedo-Tube Submarine.—Clear up to the time of the Centennial Exposition held at Philadelphia in 1876, the only idea that inventors of submarines seem to have had was to use a bomb of some sort which could be attached to the submerged hull of an enemy ship and which would blow her up.

This crude scheme, as you have seen, was not only uncertain but it was at once a difficult piece of work and very dangerous to the operator. About this time, or perhaps a little later, a Swedish engineer, named Nordenfelt, invented a torpedo which could be shot from a tube in the head of the submarine.

His early submarine had a length of 100 feet and could make 12 knots[6] on top of the water; she could be submerged to a depth of about 50 feet, when, of course, her speed was considerably reduced. She was steam-driven and had two propellers.

But the great improvement of this submarine craft over all the others that had been built before her was her torpedo tubes through which torpedoes[7] could be shot from the inside of the boat and aimed at the enemy. Besides the torpedoes, she carried two rapid-fire guns, and these made her an engine of destruction greatly to be feared. She is shown in Fig. 6.

The Invention of the Electric Submarine.—What with the amazing uses to which electricity was being put, it is small wonder that as soon as the storage battery was invented and electric motor was discovered,[8] inventors became imbued with the idea of using the mighty invisible power for running their submarine boats.

The first submarine to be propelled solely by electricity was designed and built about 1886 by Campbell and Ash, of England. The outstanding features of this undersea craft were the storage batteries, which were formed of 104 cells, and the electric motors, of which there were two and each one developed 45 horsepower.

The boat had a speed of 6 knots, and it had a cruising radius of 80 miles, without recharging the batteries. She is shown in Fig. 7. The electric submarine never got out of the experimental class, because of the imperfections of the storage battery at that early date and in virtue of the fact that its range of travel was very limited.

But the experiments were not without value, though, for they led to the use of electricity as the ideal power for undersea propulsion, as you will presently learn.

What the Gas Engine Did for the Submarine.—Greater effort to use electricity as a motive power for submarines would doubtless have been made had not the gas-engine been invented in 1888.

This new kind of engine was the ideal motive power for propelling a submarine on the surface of the sea, and at the same time it could drive a dynamo which would generate an electric current to charge the storage batteries with.

And when the boat was submerged the engine could be stopped and there was no smoke or burnt gases to escape; the storage battery then gave up its electric current, this energized the motors, and these in turn drove the propellers. This combination system of gas and electric power is used in all submarine boats at the present time.

The first engineer to combine a gas and an electric power plant in a submarine as described above was Depuy de LÔme. This French engineer turned out a wonderfully successful submarine; and this was still further perfected by another Frenchman, named Gustave ZÉdÉ. Many of the submarines used in the French Navy at the present time are of the Depuy de LÔme-ZÉdÉ type.

The Two Types of Submarines.—Two American inventors, name Lake and Holland, were working independently of each other—that is, neither knew the other was working on submarines—and each developed a different type of undersea boat. This was about 1896.

The Lake Submersible.—The first underwater boat built by Simon Lake was shaped very much like a ship. The hull was mounted on wheels, so that it could travel on the bottom of the sea if need be, for it was originally intended to be used by pearl divers and oystermen.

In the early part of this chapter I told you that the word submarine means anything that lives in, is done, or works beneath the water-line of the sea. Now, in naval engineering, submarine has come to mean an undersea craft that can dive, while an undersea boat that simply sinks on an even keel is called a submersible. So the Lake shown in Fig. 8 is a submersible, for it is not intended to dive.

The Holland Submarine.—The Holland undersea boat is a real submarine, for it can dive. The hull of this boat looked more like a whale with its tail twisted up than like a boat, as you will see in Fig. 9.

The Combined Holland and Lake Types.—The shape of the Holland submarine makes it a good undersea boat; the Lake submersible has a large deck and roomy quarters, and its shape makes it good for surface going. The result is that naval architects have combined the two types so that the new model submarines have the advantages of the older types and are without their disadvantages.

Nearly all of the boats of the submarine flotilla of the United States Navy are of the Holland and Lake types combined, as shown in Fig. 10. You will find more about these craft in another chapter.