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Rh If a percussion or impact-fuse were available sufficiently sensitive to explode with certainty on encountering balloon-cloth, the 1-pounder would be an excellent weapon for the destruction of the airship or dirigible. Every part of a shell exploding within the envelope is effective, and the fragments of a shell leave wounds in the envelope and give rise to loss of gas of a more serious character than that due to the rifle or machine-gun bullet. Beyond this the danger to the crew (and structure in the case of a Zeppelin) is considerably greater under these conditions than under equivalent machine-gun fire. It may be some time, however, before the impact-fuse reaches the required degree of perfection.

In the author's opinion there is room for a well-designed light-weight automatic to fire 14-oz. shell at a moderate velocity, say 1,200 ft. per second, with a maximum rate of 100 rounds per minute, the weight of the gun to be kept, if possible, under 100 lb; the length should be kept as short as the requirements of the internal ballistics permit. The value of such a weapon, however, would depend almost entirely upon the development of suitable ammunition, and in particular, as already pointed out, the perfection of the impact-fuse to a point not yet within sight.

§ 54. Armour in its relation to Armament. We have already given considerable attention to the question of armour in connection with the primary function of the aeronautical Arm — the attack on and co-operation with the other Arms of the Service. It is now time to extend our study to the secondary function of the Arm, and discuss the question in relation to problems of aerial attack and defence. The first instalment of the conditions which need to be fulfilled by the aeroplane constructor arises directly from the consideration of the primary function; thus, it is already given us that the armament