which was launched in Barcelona, Spain in 1864. The submarine became a potentially viable weapon with the development of the Whitehead torpedo, designed in 1866 by British engineer Robert Whitehead, the first practical self-propelled or "locomotive" torpedo. The spar torpedo that had been developed earlier by the Confederate States Navy was considered to be impracticable, as it was believed to have sunk both its intended target, and probably H. L. Hunley, the submarine that deployed it. The Irish inventor John Philip Holland built a model submarine in 1876 and in 1878 demonstrated the Holland I prototype. This was followed by a number of unsuccessful designs. In 1896, he designed the Holland Type VI submarine, which used internal combustion engine power on the surface and electric battery power underwater. Launched on 17 May 1897 at Navy Lt. Lewis Nixon's Crescent Shipyard in Elizabeth, New Jersey, Holland VI was purchased by the United States Navy on 11 April 1900, becoming the Navy's first commissioned submarine, christened . Discussions between the English clergyman and inventor George Garrett and the Swedish industrialist Thorsten Nordenfelt led to the first practical steam-powered submarines, armed with torpedoes and ready for military use. The first was Nordenfelt I, a 56-tonne, vessel similar to Garrett's ill-fated (1879), with a range of , armed with a single torpedo, in 1885. A reliable means of propulsion for the submerged vessel was only made possible in the 1880s with the advent of the necessary electric battery technology. The first electrically powered boats were built by Isaac Peral y Caballero in Spain (who built ), Dupuy de Lôme (who built ) and Gustave Zédé (who built Sirène) in France, and James Franklin Waddington (who built Porpoise) in England. Peral's design featured torpedoes and other systems that later became standard in submarines. Commissioned in June 1900, the French steam and electric employed the now typical double-hull design, with a pressure hull inside the outer shell. These 200-ton ships had a range of over underwater. The French submarine Aigrette in 1904 further improved the concept by using a diesel rather than a gasoline engine for surface power. Large numbers of these submarines were built, with seventy-six completed before 1914. The Royal Navy commissioned five s from Vickers, Barrow-in-Furness, under licence from the Holland Torpedo Boat Company from 1901 to 1903. Construction of the boats took longer than anticipated, with the first only ready for a