The Fortification Board in their report say: “It is not generally considered possible to bar the progress of an armored fleet by the mere fire of a battery; some obstructions sufficient to arrest the ships within effective range of the guns is necessary. The kind of obstruction now relied upon is the torpedo, in the form of a submarine mine, and, except in special cases, exploded by electric currents which are so managed that the operator on shore can either ignite the mine under the ship’s bottom, or allow the ship to explode it by contact. In deep channels the submarine mines are buoyant; in comparatively shallow waters they are placed upon the bottom—the object in both cases being to touch or nearly approach the hull of the vessel. Submarine mines are not accessaries to defence, but are essential features wherever they can be applied.” The Senate Committee on Ordnance and War-ships reported: “Concerning another class of torpedoes, ‘fixed’ or ‘anchored’ or ‘planted,’ technically known as submarine mines, there is a great popular misapprehension. Their value is greatly overestimated. They require picked and trained men for their management, electrical apparatus for their discharge and for lighting up the approaches, stations on shore secure against sudden assault, a flanking fire of canister and case shot and of machine guns (themselves protected), light draught picket-boats, and the overshadowing protection of armored forts and heavy guns. None of these things can be extemporized. The submarine mine alone is of little use, and it must accompany, not precede, more costly and less easily prepared means of defence.” There is, however, a more definite agreement as to the value of torpedo-boats. The Fortification Board declare: “Among the most important means of conducting an active defence of the coast is the torpedo-boat, which, although recently developed, has received the sanction of the nations of Europe, each one of which now possesses a large number of these vessels. Their use will be quite general. First, in disturbing blockades, and preventing these from being made close, as no fleet would like to lie overnight within striking distance of a station of these boats; secondly, in attacking an enemy’s ship enveloped in fog or smoke; thirdly, in relieving a vessel pursued by the enemy; and fourthly, in defending the mines by night and by day against attempts at counter-mining, and in many other ways not necessary to recapitulate.” Impressed with the utility of this mode of defence, the Board recommended the construction of one hundred and fifty of these boats, and the organization of a special corps of officers and men from the navy trained to their use.