the surface. We may presume that in any operations of the description contemplated, one or more destroyers or light cruisers will accompany the aircraft scout, and the conning-tower of the submarine will be blown away within a few seconds of its appearance.
§ 75. Attack on Submarine by Aeroplane. Destruction by Bomb. It is not in any sense certain or likely that the operations of aircraft in relation to the submarine will be confined to observation. In the opinion of the author, aircraft, whether aeroplane or dirigible, will prove to be the submarine's most dangerous enemy, the submarine being attacked by bombs charged with high explosive while submerged. Owing to the absence of any danger of counter-attack the aeroplane may fly as low as deemed desirable to obtain the necessary accuracy of aim, and much of the difficulty commonly associated with bomb-dropping will accordingly vanish. Such an attack is depicted (somewhat diagrammatically) in Fig. 16, in which, for the purpose of illustration, the machine is shown as flying at a quite low altitude of about 60 ft., and when at the point A to drop a bomb, which, having the velocity of the machine in flight, describes the trajectory A B whilst the machine is travelling to the point C; the motion of the submarine in the intervening time is indicated by the dotted outline. It is not to be anticipated that in practice it will be found necessary to come down to as low an altitude as that shown in order to ensure the degree of accuracy required.
The type of bomb appropriate to the duty in question, although not greatly different from that required in connection with land service, will need a certain amount of consideration. In view of the fact that the size of the hole blown in the skin of the submarine is not important, the charge of explosive may be quite moderate; probably 10 lb, or 15 lb, of wet gun-
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