Page:Victory at Sea - William Sowden Sims and Burton J. Hendrick.djvu/268

whatever depth it might be sailing, would be likely to strike one of these obstructions. This required such a large number of mines as to render the whole project impossible. We Americans may take pride in the fact that it was an American who invented an entirely new type of mine and therefore solved this difficulty. In the summer of 1917 Mr. Ralph C. Browne, an electrical engineer of Salem, Mass., offered a submarine gun for the consideration of Commander S. P. Fullinwider, U.S.N., who was then in charge of the mining section of the Bureau of Ordnance. As a submarine gun this invention did not seem to offer many chances of success, but Commander Fullinwider realized that it comprised a firing device of excellent promise. The Bureau of Ordnance, assisted by Mr. Browne, spent the summer and autumn experimenting with this contrivance and perfecting it; the English mining officers who had been sent to America to co-operate with our navy expressed great enthusiasm over it; and some time about the beginning of August, 1917, the Bureau of Ordnance came to the conclusion that it was a demonstrated success. The details of Mr. Browne's invention are too intricate for description in this place, but its main point is comprehensible enough. Its great advantage was that it was not necessary for the submarine to strike the mine in order to produce the desired explosion. The mine could be located at any depth and from it a long "antenna," a thin copper cable, reached up to within a few feet of the surface, where it was supported in that position by a small metal buoy. Any metallic substance, such as the hull of a submarine, simply by striking this antenna at' any point, would produce an electric current, which, instantaneously transmitted to the mine, would cause this mine to explode. The great advantage of this device is at once apparent. Only about one fourth the number of mines required under the old conditions would now be necessary. The Mining Section estimated that 100,000 mines would form a barrier that would be extremely dangerous to submarines passing over it or through it, whereas, under the old conditions, about 400,000 would have been required. This implies more than a mere saving in manufacturing resources; it meant that we should need a proportionately smaller number of mine-laying ships, crews, officers, bases, and supplies all those things which are seldom considered by the amateur in