numerical increase in the air raids of the future. The author is inclined to believe that the tendency of the future will be towards machines of not too great size each dropping a comparatively few bombs, possibly no more than one large bomb being carried by each machine. This conclusion arises as a deduction from the fact that when machines are acting in great numbers it will not be possible (neither will it be politic) for any given machine to pass more than once over the object of attack, hence if a large number of bombs be carried they will need to be released almost simultaneously. Under these conditions a single large bomb of equal weight will possess a far greater potential capacity of destruction.
§ 118. Aircraft v. Submarine. Discussing the value of Aircraft as countering submarine activity in Chapter XI., the subject has perhaps been handled too much in detail, and some of the broader considerations have not been given sufficient prominence. It is not to be supposed that it will always be found possible on locating a submarine, to follow it up and immediately effect its destruction, since in the turbid waters of the Channel and parts of the North Sea (especially in rough weather) a submarine, by diving deeply and steering by gyro-compass, could frequently effect its escape. Quite apart from the method of attack it is the author's view that with a sufficiently numerous air reconnaissance, the enemy submarine will be subject to continuous and unremitting pressure to such an extent that, even where it may escape destruction, it will commonly fail in its object. Thus, taking the case of the large submarine having a great radius of action, it is impossible to make a long passage such as an incursion into the Atlantic from the Heligoland Bight round Cape Wrath, without steaming on the surface for a consider-
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