Those of us who are no longer children can remember the first practical submarine, but the idea was by no means new, as we shall see. Of course the idea of a submarine boat was to be able to attack the enemy without being seen. Away back before the time of Christ the ancients had the idea of going down under water in a kind of diving bell. This was not a ship but it was a means of living under water.

Between three hundred and four hundred years ago an English gunner invented a submarine boat with leather joints so that he could make it larger or smaller by turning some screws inside. But why should he wish to make it smaller? Suppose he had it so arranged, when at its largest size, just to float nicely on the surface of the water. Then if he were to make it take up less room, it would still be as heavy but it would not be supported by so much water, so it would be less buoyant, and would therefore sink below the surface. But how could this old-time English gunner breathe when his strange boat went under the water? He had a long mast, which was in reality a tube through which he got air. Of course the top of this mast had always to be above the surface of the water.

Then in the time of King James I. a Dutchman invented a submarine which he tried in the River Thames. It is said that King James once went a trip with him, but possibly it remained upon the surface on that occasion. This same Dutchman proposed to King Charles I. that he should use submarines against the French, but this was not done.

The first time that any kind of submarine was actually used in war was in the American War of Independence, about one hundred and fifty years ago. An American made a small wooden submarine, by which he could go right under an enemy ship and attach an explosive bomb to the bottom of the ship. As you know from a previous chapter, the warships of these days were all wooden, and this enabled the man in the small submarine to fasten a large screw-nail into the bottom of the ship, and to this was attached a short piece of wire rope, at the end of which was the bomb. The bomb contained an explosive, and a clockwork which exploded the bomb in one hour after it was set.

This daring American succeeded in going right beneath one of our British warships and fastening a bomb to the bottom of the ship. He evidently found difficulty in fixing the screw; at least he did not make it very secure, which was fortunate for our sailors. One hour later there was an explosion, but it took place a long way from the ship, showing that the bomb had drifted away.

There were many other attempts to make submarines, but the inventors got very little encouragement. Some of these early submarines were rowed by oars under the water, while others had propellers which were driven by turning a crank either by the hands or by foot pedals.

A famous American, Robert Fulton, who invented the first American steamship, was also the inventor of a submarine, and he offered to make submarines by which Napoleon might attack Great Britain. The offer was not accepted.

Another American thought to rescue Napoleon from his imprisonment on the island of St Helena. This American actually constructed a submarine with this object in view, but the banished French Emperor died before the boat was ready. The submarine which the American used in the War of Independence in his attempt to blow up a British warship was called a "turtle." It was a small upright boat in which one man could sit. He could submerge this boat, and while under the water he could continue to row the boat with oars.

It is interesting to note that it was this American who invented a safety keel which he could let go if necessary if anything went wrong with his submarine. This idea was adapted later by the French and the Americans when they came to make practical submarines.

The attempt to blow up a British warship with the aid of one of these turtles took place in the American War of Independence (1775). Nearly a hundred years later, another and more successful attempt was made by an American in the American Civil War (1864). This new idea was to carry the explosive at the end of a spar projecting from the bow of the submarine, and then run under the water right against the warship, and thus blow it up. One warship was blown up in this manner during the Civil War, and others were damaged, but it is evident that the submarine and its occupants could not escape being blown up along with the ship. We shall see later that this arrangement was more like a torpedo with a man on board than like a submarine.

A Swedish engineer was the first to invent a submarine with a steam-engine. He could travel along on the surface with his steam-engine, but how could he travel under water? When he was ready to submerge (go under water) he put his fire out, and he had to depend upon what steam remained in the boiler and in some steam chests. Of course this meant that he could not travel very far under water. However, he was the first to make a ship go under water by means of an engine.

Then the French, in 1889, began in earnest to invent reliable submarines, and by this time electric motors had been invented. This was a great help. You know how electric motors can be driven by means of batteries which are not dependent upon the air as engines are.

The first French submarine was just about the size of an ordinary rowing boat, and could carry two, or at most three, men. It had now become apparent that to be useful a submarine must be larger, and so they went on experimenting with larger and yet larger boats until these were 100 feet in length.

One of the French submarines was able to approach a large French warship and fasten an unloaded torpedo to the bottom of the ship without being observed by those on board. In actual warfare the submarine could have sent the torpedo under water from some distance, which would have been a much easier thing than going right up to the ship, as was done in the experiment.

While the French were making these experimental submarines the Americans were also making practical experiments, and with equal success. Indeed, when our Navy saw that those could be really practical vessels, they too began to build some submarines on similar lines.

By this time the conning-tower had been invented. Then this was merely a sort of cupola about 2 feet in diameter and 18 inches in height, by which the men could enter within the boat. You know how this turret or conning-tower now stands right up like a tower. The men have to climb up from the deck by a ladder to get into the conning-tower.

Suppose we go an imaginary cruise on a modern submarine. We get on board while the boat is in harbour, and at this time the boat floats well out of the water, like an ordinary ship. Its high conning-tower stands up at the middle of the boat. There are several submarines in the harbour, and we watch one of these leaving; the crew have all gone below, with the exception of one or two men on deck, who keep at the base of the conning-tower. We see two officers in the conning-tower looking out. So long as she is travelling on the surface of the water the submarine uses her oil engines to drive her propellers, and she can go along at about 20 miles per hour.

Watching the submarine going out to sea, we find that she looks like a cloud of white spray moving quickly along the surface. Then after all the men have climbed in through the conning-tower, and the lid or cupola is securely fastened, we see her give a heave forward and dip under the water, leaving only her conning-tower visible above the surface. How did she manage to do this? By making herself heavier. This she does by partly filling her tanks with sea-water. In this position the submarine is said to be trimmed ready for diving right down under the water. Each sailor is now at his particular post, and he must remain there as long as the submarine is under water. The duty of some of the men is to remain at the pumps ready to fill the tanks with sea-water, and make her heavier and yet heavier, until she sinks down to the required depth. Other men are standing at the electric motors which drive the propellers and cause the ship to move along under the water like a great fish. Other men are at the tubes, ready to launch torpedoes whenever ordered to do so.

Suppose we are now on board a submarine and we have trimmed ready for diving. Perhaps we had expected to find a sort of awesome silence, but we find we can scarcely hear one another speak for the noise of the machinery. The men give their whole attention to their various duties; orders must be promptly obeyed. Only the officer at the periscope can see what is happening on the surface. We shall have a talk about the periscope when we get to the surface again.

Perhaps you wonder where is the cage of white mice that you have heard is always carried on a submarine. There are none. At first the sailors did always take some white mice with them, as these little creatures were able to detect the presence of any poisonous fumes long before the men could do so. If the mice began squealing, the men knew it was time they were going to the surface for fresh air. And why do they not carry the white mice with them now? Because the boats are made so safe that there is no need.

The sailors are perfectly calm, although they know very well that they are running great risks in cruising about under the water. They have volunteered for this work; no man need go on a submarine unless he desires to do so. There are always plenty of sailors willing to go.

Suppose you are a sailor on board a submarine which is taking part in a great naval war. We submerge and we have no idea where we are going; we are entirely at the mercy of the officer at the periscope; he decides when we may safely go to the surface, and when we must keep out of sight. After we have been travelling along for some time in the North Sea our officer at the periscope becomes puzzled. He sees a red buoy behind our boat, and this same buoy was there the last time he looked, and yet we have been travelling along.

It becomes evident to him that we are carrying the buoy along with us. He steers to the right and then to the left, yet this buoy follows us wherever we go. We must have caught the chain to which the buoy is attached. Just then the officer notices that a small steamer is following us and the buoy. Listening at the sounding apparatus, the officer hears the beats of several screw-boats, and he feels sure that a number of enemy torpedo boats are coming towards us. Very soon the officer is able to see by his periscope no fewer than five torpedo boats arranging themselves in a circle around us. The order comes to the men at the pumps to fill the water tanks, and down we go to a lower level.

Just then our boat begins to roll and heave in a most extraordinary manner. We are surprised, for even when it is rough on the surface we do not feel any motion whatever at this depth. It becomes evident that we are caught in an enemy net: a heavy wire netting set as a trap for submarines. We are becoming hopelessly entangled in the net, but our officer is not going to give in without putting up a good fight. For an hour and a half we try to shake off the net, but cannot. As a last attempt, our officer decides to make the submarine as heavy as possible, in the hope of breaking the netting. The men by the pumps get orders to pump in more water into the tanks, and still more. Some anxious moments, then a sudden shock, and we know that we are free once more.

But we remain down at a depth nearly 100 feet below, the surface. In the struggle our compass and some other instruments have been put out of order, so we must just wait under water till our officer thinks it safe to rise. It is a long wait. It seems like days and days, and we can scarcely believe that only eighteen hours have passed when the officer decides to go to the surface. Very gradually we let the water out of the tanks. We must not attract the attention of the enemy if he is still about. At last our periscope pops above the surface, and there is the enemy still patiently waiting. We try to steer round, but we find that our steering-gear is out of order, so we sink to the bottom again, and for six hours we work at the steering-gear and the damaged instruments, putting them into working order.

Once more we rise to the surface very quietly, but it is evident that our periscope is seen. For one of the torpedo boats makes straight for us, in an endeavour to ram us. We lose no time in diving under once more, and for two hours we remain hidden. Then we very cautiously turn round and steam away like a great fish. At nine o'clock in the evening we rise to the surface and find ourselves clear of the enemy; our adventure ends much more happily than we had expected at one time. The foregoing imaginary adventure has been based upon a description given to the American papers by an enemy submarine commander, and it serves to show to what a degree of perfection submarines have been brought.

I have heard boys and girls, when at the sea-coast, say that they wish they could walk along on the bottom of the ocean. Of course that is impossible, but you may be interested to know that some years ago an American built a sort of submarine car that could travel along on the bottom of the ocean. One boy suggests that if this machine were travelling along below the sea the occupants could not see where they were going, and therefore they might collide with some great rock, and damage the machine. But this submarine car had a powerful electric searchlight, which shone right in front and let the driver see where he was going.

This car was really a submarine boat with very large wheels, as large as those of an ordinary cart. The boat could travel along on the surface by means of a propeller, but when down on the bottom the wheels were driven round and the car could travel, but only at a smart walking pace. The vessel could not go down to a depth greater than 100 feet, as it was not strong enough to withstand the great water-pressure at a greater depth. If the car came upon a soft muddy bottom the propeller could be used instead of the wheels to drive her along.

Perhaps you think the inventor must have been "a little queer" to construct a submarine car of this kind, but he did not do this for amusement. His idea was to enable divers to work at a sunken wreck, using his submarine car as their base instead of a boat away up on the surface. He could take divers down to the bottom and drive his car to any desired position, then, by means of water-tight compartments, the divers could leave the car. The divers had telephones in their helmets, so that they could talk to those who watched them from the submarine boat. The divers could also talk to one another. Although this submarine car is not, properly speaking, a war invention, it was proposed that it could enter a harbour and blow up the enemy ships or destroy the mines protecting a harbour. Although this submarine proved to be able to travel 1000 miles without difficulty, it has remained merely an interesting experiment.

You know how it has become the custom to call submarines by a letter and a number instead of by a name, as we do the larger war vessels. In connection with warships we think of Hercules, Irresistible, Queen Elizabeth, and so on; our submarines are called E9, E12, D5, and such like. In the December (1915) number of the journal called The Navy there appeared some verses which made reference to this want of name. The submarine E9 had sunk some German ships, and the E3 had been sunk in the North Sea. Here are two of the verses: