Who first thought of an under-sea boat, nobody knows. It certainly was not Fulton, for David Bushnell was floating about New York Bay in the days of the Revolutionary War, in his primitive submarine, the Turtle. This boat, so-called from its resemblance to a turtle, floating tail downward and with a conning tower for a head, was literally a one-man boat. Two "oars" or "screws" worked from the inside by a crank propelled it, and the operator directed its course by means of a rod attached to the rudder, which he held under his arm.

This absurd little submarine, however, came near blowing up the British frigate Eagle, as she lay at anchor with her guns trained on Manhattan Island. On the after deck of the Turtle were two hollowed-out pieces of oak filled with gunpowder, arranged to explode, after the operator had bored a hole in the frigate, had deposited his crude torpedoes, and was far enough away to be out of range. But the Eagle was copper sheathed, and it was impossible to bore into the hull. Two other attempts were made to blow up British ships with the aid of Bushnell's boat, but both failed. The boat finally came to a sad end, when a sloop carrying her, sank, submarine and all. We have David Bushnell to thank, however, for the idea of the conning tower and the propeller, and the actual beginnings of the torpedo.

The Civil War aroused new interest in the submarine. The Hundley, operating in Charleston harbor, actually torpedoed and sank the Housatonic, but the rush of water from the exploding torpedo sank the Hundley  with all her crew. So the first victim of the submarine, and the first under-sea boat to sink a warship prior to 1914, lay side by side at the bottom of the sea.

The first man to succeed in making a practicable submarine was John P. Holland, who was born in Ireland in the year 1842.

Holland was busy on an under-sea boat in 1862. On coming to Paterson, New Jersey, in 1873, where he became a teacher, he continued to work away at his plan after school hours. He built altogether seven submarines, none of which amounted to much. Finally, in 1898, he launched the Holland No. 8. This was a porpoise-like craft, fifty-three feet long and ten feet wide, with a single torpedo tube. It plunged head on, like a duck, when water was let into specially arranged compartments, and it rose to the surface when the water was driven out by compressed air,—all in five seconds. It could be held at any desired depth under water, where it moved about like a fish. When afloat it had a speed of eight miles an hour, and a cruising radius of 1500 miles. After seeing the Holland, Admiral Dewey said, "If they (the Spaniards) had had two of these things at Manila, I could not have held it."

Within the next few years Holland sold plans for submarines to the United States, England, Japan, and Germany.

The submarines in use at present are often 200 to 300 feet long, with crews of from twenty-five to eighty men. They cross and recross the Atlantic Ocean with ease. The Deutschland brought over the first cargo of freight from Europe, landing at Baltimore in 1916.

When afloat, heavy oil-burning engines drive the submarine along at a rate of twenty to thirty miles an hour. When submerged, electricity is used, as it makes less heat and throws off fewer odors to pollute the air, which has to be safeguarded, lest the crew suffocate. A submarine can remain under water twenty-four hours at a time, but to be comfortable for the crew, it needs to come to the surface five or six times a day, to pump in a supply of fresh air.

Submarines no longer dive straight down. After everything is shut tight to keep out the water, the bow of the submarine is tipped slightly, and the boat glides gently down to the desired depth. Fifty feet is the ordinary depth, but they can dive to a depth of two hundred feet. Submerging is more or less dangerous, however, and frightful accidents have occurred. Something may go wrong with the machinery. Or if they dive too deep the great pressure of the sea may crush the hull. Or, as happened with the American F-4, when the entire crew was lost, acids from the electric batteries may eat away the rivets so that the hull may cave in.

The latest submarines have both eyes and ears. The eye is the periscope, so necessary to submergence. The periscope consists of a system of mirrors inside a tube, which is extended, when the boat is submerged, to a distance of fifteen to twenty feet above the surface of the water. By looking into the mirror at the bottom of the periscope, the captain sees everything that happens above. The periscope thus enables the submarine to locate ships, and to aim its deadly torpedoes without unnecessary exposure.

When afloat, a wireless outfit serves for ears. But submarines can also hear when under water. A steel disk, eighteen to twenty inches in diameter, is attached to the hull, and this disk by means of an electric current acts as an under-sea wireless. The steel ear has still another use. The engines of vessels in motion make considerable noise. This is carried through the water and vibrates the submarine's ear. After a little practice it is easy for the listener to tell the direction from which the noise comes, and the locality of the ship.

Submarines now carry both torpedoes and cannon. When it is safe for the submarine to be afloat, the vessel to be destroyed is more likely to be shelled by cannon and afterwards torpedoed at short range.

The submarine is thus a monster that dives, and floats, and moves with animal-like quickness; that sees, and hears, and has mile-long-arms of more than giant strength.