tinuous and hot engagement of about a quarter of an hour's duration. From the point of view of recoil the machine-gun is quite harmless; the mean recoil of the Lewis gun firing Mark VII, ammunition amounts to slightly less than 2.5 lb, per shot per second, or at 600 per minute the recoil reaction is about 25 lb.
§ 48. Rapid Fire. Machine-Guns Multiply Mounted. In view of the advantages of rapid fire, it would seem desirable to increase the speed of fire of the machine-gun to the maximum extent possible. When, on land, the obvious thing to do under similar circumstances would be to bring two guns into action, a similar course is not possible on a flying machine, owing to the weight of the additional gunner. An extra man must either mean the sacrifice of a couple of thousand rounds of ammunition or a couple of hours' petrol supply, neither of which alternatives can be entertained. The conditions indicate the mounting of machine-guns in pairs, or the design of double or triple-barrel guns, the breech actions of which would be independent, but so arranged that they could be fired one, two, or three at a time; by this means a "burst" of twenty-five or thirty bullets could be got off in less than one second. It may be found that a gun designed to take the 0.45 service revolver or automatic-pistol ammunition will be better suited to the conditions than the present weapon, in which the service rifle (Mark VII.) ammunition is employed. Such a gun would be far more handy, owing to the shortness of the cartridge, and would be furnished with a comparatively short barrel; also the magazine could be made of more compact form better to permit of the multiple-barrel design. Beyond the above, the shattering effect of the round-nose pistol bullet is known to be far greater than that of the 0.303 spitzer, so that greater injury will be inflicted on any spars or other structural members that may be hit.
