American inventors were therefore well qualified to deal with this problem of communicating by sound under the water. A listening device placed on board ship, which would reveal to practised ears the noise of a submarine at a reasonable distance, and which would at the same time give its direction, would come near to solving the most serious problem presented by the German tactics. Even before the United States entered the war, American specialists had started work on their own initiative. In particular the General Electric Company, the Western Electric Company, and the Submarine Signal Company had taken up the matter at their own expense; each had a research department and an experimental station where a large amount of preliminary work had been done. Soon a special board was created at Washington to study detection devices, to which each of these companies was invited to send a representative; the board eventually took up its headquarters at New London, and was assisted in this work by some of the leading physicists of our universities. All through the summer and autumn of 1917 these men kept industriously at their task; to such good purpose did they labour that by October of that year several devices had been invented which seemed to promise satisfactory results. In beginning their labours they had one great advantage: European scientists had already made considerable progress in this work, and the results of their studies were at once placed at our disposal by the Allied Admiralties. Moreover, these Admiralties sent over several of their experts to co-operate with us. About that time Captain Richard H. Leigh, U.S.N., who had been assigned to command the subchaser detachments abroad, was sent to Europe to confer with the Allied Admiralties, and to test, in actual operations against submarines, the detection devices which had been developed at the New London station. Captain Leigh, who after the armistice became my chief-of-staff at London, was not only one of our ablest officers, but he had long been interested in detection devices, and was a great believer in their possibilities.