[11] But Fulton’s _Nautilus_ could not possibly have made the dives with which she is credited except by the use of the horizontal rudders which she possessed in conjunction with the push of her man-power propellor. Holland had carefully studied the plans and letters of Bushnell and Fulton. [12] Mr. J. F. Waddington used vertical propellers in tubes through the vessel for keeping her on an even keel or submerging when stationary, on a small electric submarine he invented, built and demonstrated at Liverpool in 1886. [13] Quotations in this chapter are from Mr. Lake’s articles published in “International Marine Engineering,” and are here reprinted by his kind permission. [14] Electric current. [15] From an article by Admiral Selfridge in the “Outlook.” [16] The velocity of sound in dry air at a temperature of 32 degrees Fahrenheit is about 1087 feet a second, in water at 44 degrees, about 4708 feet a second. [17] The sound of the first gun of the salute fired by the Russian fleet in Cronstadt harbor to celebrate the coronation of Alexander II in 1855 was the signal for the crew of the submerged submarine _Le Diable Marin_ to begin singing the National Anthem. Their voices, accompanied by a band of four pieces, were distinctly heard above the surface. This novel concert had been planned by Wilhelm Bauer, the designer of the submarine and one of the earliest students of under-water acoustics. He succeeded in signaling from one side of the harbor to another by striking a submerged piece of sheet-iron with a hammer. [18] “Scientific American,” January 28, 1911, page 87. [19] “Scientific American,” November 23, 1912. [20] Titherington’s History of the Spanish-American War, p. 139. [21] _Ibid._, page 202. [22] He had done notable work with mines himself, during the Russo-Turkish War of 1878. [23] This was a very popular type with the Confederate Torpedo Service in the Civil War. [24] London, Jan. 4.--A British official statement issued to-day says: “Sir Edward Grey, secretary for foreign affairs, has answered the complaint by the Germans through the American embassies regarding the destruction off the coast of Ireland of a German submarine and crew, by the British auxiliary _Baralong_, by referring to various German outrages. “Sir Edward Grey offers to submit such incidents, including the _Baralong_ case, to an impartial tribunal composed, say, of officers of the United States navy.