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. [Illustration: A MINE-PLANTING SUBMARINE DESIGNED IN BERLIN BY SIMON LAKE IN 1895 FOR THE RUSSIAN GOVERNMENT] Twentieth Century Submarines. We have given an epitome of the development of the submarine vessel up to the opening of the twentieth century. It had now reached a successful status of achievement and during the early years of that century was to display a remarkable progress. Holland and Lake may be looked upon as the parents of the modern development of the submersible boat, their designs being at the base of the great European progress. France took up the work actively, its most successful early vessel being the “Narval,” built in 1899. This was 118 feet long by 8 feet 3 inches beam, 106 tons surface and 168 submerged displacement. She was a double-deck vessel controlled by Lake hydroplanes, and had installed steam power for surface travel and electric power for undersea work. The French at this time kept their methods secret, and no useful type had been developed in England, the result being that a plant was provided for the building of Holland boats in that country. Germany used the Lake devices, which had not been patented in that country and were made use of by the Krupps. Thus it appears that the modern submarines, as now built and used in the navies of the world, owe their success to principles of construction and devices for control originated and developed by American inventors. Engine Power.