Many brilliant ideas were due to Captain Ryan's clever brain.
I doubt whether the debt due to Admiral Duff and Captain Fisher and their staff for their great work can ever be thoroughly appreciated, but it is certainly my duty to mention it here since I am better able to speak of it than any other person.

In saying this I do not wish to detract in the least from the value of the part performed by those to whose lot it fell to put the actual schemes into operation.

Without them, of course, nothing could have been accomplished.
When the Anti-Submarine Division started in December, 1916, the earlier devices to which attention was devoted were: (1) The design and manufacture of howitzers firing shell fitted to explode some 40 to 60 feet under water with which to attack submarines when submerged.
(2) The introduction of a more suitable projectile for use against submarines than that supplied at the time to the guns of destroyers and patrol craft.
(3) The improvement of and great increase in the supply of smoke apparatus for the screening of merchant ships from submarines attacking by gunfire.
(4) A great increase in the number of depth charges supplied to destroyers and other small craft.
(5) The development of the hydrophone for anti-submarine work, both from ships and from shore stations.
(6) The introduction of the "Otter" for the protection of merchant ships against mines.
(7) A very great improvement in the rapidity of arming merchant ships defensively.
(8) The extended and organized use of air craft for anti-submarine work.
(9) A great development of the special service or decoy ship.
(10) The introduction of a form of net protection for merchant ships against torpedo fire.
Other devices followed, many of which were the outcome of work in other Admiralty Departments, particularly the Departments of the Director of Naval Ordnance and the Director of Torpedoes and Mines, working in conjunction with the Anti-Submarine or the Operations Division of the Naval Staff.

Some of the new features were the development of depth-charge throwers, the manufacture and use of fast coastal motor-boats for anti-submarine work, the production of mines of an improved type for use especially against submarines, very considerable developments in the use of minefields, especially deep minefields, including persistent mining in the Heligoland Bight and the laying of a complete minefield at varying depths in the Straits of Dover; also, after the United States entered the war, the laying of a very extensive minefield right across the northern part of the North Sea.

The provision of "flares" for illuminating minefields at night, and a system of submarine detection by the use of electrical apparatus were also matters which were taken up and pressed forward during 1917.