The type of these vessels was what became known as the "diving." They were controlled by a rudder placed at the stern of the vessel and acting in both a horizontal and a vertical direction, the force of the screw propeller driving the boat forward in the direction desired. In 1904 the navy of the United States possessed eight Holland boats and there were also a number of them in the British navy.

Mr. Lake's design, offered in 1893 but not accepted, had as its novel feature a plan by which a door could be opened in the bottom of the ship and the crew leave and enter it in diving suits, the water being kept out by the force of compressed air. To maintain the vessel on an even keel he introduced four vanes, called 'hydroplanes," for regulating the depth of descent. By aid of these and the horizontal rudder it was found that the vessel would run for hours at a constant depth and on a level keel. There were other devices for diving or rising to the surface.

In 1901 Mr. Lake built a large vessel of this type which was sold to the Russian government and was in commission at Vladivostock during the Russian-Japanese Wai. He afterwards received orders from this and other governments for a number of vessels of the even-keel type, and his principles of control have since been generally adopted as the safest and most reliable controlling agency for under-water craft.

We have not in the above brief statement described all the efforts to invent a satisfactory under-water boat. In several of the nations of Europe experiments, more or less available, had been tried, but the most practical results were achieved by the American inventors, Bushnell, Fulton, Davy, Holland and Lake. It will suffice here to say that the most successful of submarines were those constructed by Holland and Lake. An important addition was made in 1901 in a French boat, the "Morse," built at Cherbourg. The difficulty of navigators telling where they were when under water, and of changing their course safely without coming to the surface to reconnoitre, was in a large measure overcome by the addition of a "periscope." This, rising above the water, and provided with reflecting lenses, enabled the steersman to discover the surface conditions and see any near vessel or other object. The "Morse" was able to sink in seventy seconds and her crew could remain under water for sixteen hours without strain.

A Mine-planting Submarine Designed in Berlin by Simon Lake in 1895 for the Russian Government.