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.