There is, at any rate, one point on which prophecy as to the future of submarines (if they are allowed by International Law to continue to develop) is safe: at present a boat has to travel submerged by electric power, because that is the only form of propulsion we know which does not consume air. When an engine arrives which can propel a boat under water by abstracting the necessary oxygen from the surrounding sea, we will have made the submersible a commercial proposition. A properly streamlined body moves faster under than on the surface of water, and with a submersible internal combustion engine there would be in all probability a doubling of the speed of ships. That such a type of engine will come there is little doubt, and when it is remembered that water is a far cheaper protection from shells than is armour-plate, a field for prophecy is opened which is much too big and tempting to venture into here. Whatever happens, the German policy of torpedoing merchant ships without warning must be made not only illegal, but unsafe for a nation adopting it; the use of this weapon by the enemy has made the word "submarine" one of reproach; the submarine personnel of every allied navy feels that an honourable weapon has, on its first appearance in a great sea war, had its name degraded by a section of its users. If these notes of mine serve no other purpose, they will at any rate do something towards differentiating between the submarine and the U-boat. If the name of the weapon is to become a term of reproach, it is better to particularise and to spare the honour of the Allied Navies. I am going to relate an incident which occurred during the war. It was not in the presence of the enemy, and so there is little direct connection between it and a War History. But it is illustrative of the ideas of the Submarine Service in that it evoked little comment among the Flotillas, the standard shown by the personnel being considered to be normal, and in accordance with accepted practice.