Page:Encyclopædia Britannica, Ninth Edition, v. 11.djvu/301

Rh MACHINE GUNS.] GUNMAKING 287 positions, is here represented in the act of clutching the base of the cartridge case, which is withdrawn as the locks retreat down the slope of the cam, till at X it falls through an aperture to the ground. The line ab marks the com mencement of the rifling. In fig. 20 the drum T consists of a number of vertical channels radiating from the centre. The cartridges are arranged horizontally, one above the other, in these channels, bullet ends inwards. The drum revolves on the pivot b (fig. 23), and the cartridges fall through the aperture B. When all the channels are emptied, a full drum is brought from the limber, and sub stituted for the empty one. Each barrel fires in turn as it comes to a certain position, so that by turning the handle quickly an almost continuous stream of bullets can be FIG. 27. Nordenfelt Machine Gun. 1-10, parts of frame; 11, breech plug; 12, striker; 13, extractor; 14, cartridge receiver; 15-18, 23-31, lock and trigger parts; 19-22, locking action; 32-35, load- ing action; 36-39, cartridge receiver; 40, cover ; 41-44, parts of hand-lever ; 45-49, traversing action; 50-55, elevating and trailing action ; 56, 57, hopper and slide. ejected. An experimental pattern of Gatling has been lately tried, fitted with a multiplying arrangement which could be made to fire nearly 1000 shots a minute. In fio-. 21 an automatic traversing arrangement is shown, which can be put in or out of gear as desired, and by means of which the amount of traverse can be regulated. The spindle gg turns the wheel A, projections on which act on the arm F, and traverse the breech through a small arc, thus spreading the bullets laterally over the required front. Effective though this piece is for land service, especially in defending approaches, it is scarcely suitable for the navy, as the mobility of the boats or vessels carrying it causes immense waste of ammunition, it being impossible to lire more than a, few rounds at the object before an important irden- change of direction occurs. The Nordenfelt machine gun, tgun. shown in figs. 27 to 31, is found specially suitable under these circumstances. The barrels are here placed horizon tally, and have no movement. A box containing the locks, bolts, strikers, and spiral springs, one of each correspond ing to each barrel, 28, moves straight back- Fig. 29. wards and forwards when worked by the handle of the lever on the right. When the box is drawn back the cartridges fall from the holder on the top into the carriers simul taneously. When the box is pushed forward the bolts push the cartridges into the barrel, cocking-catches compress the spiral springs, the lever releases the catches one after the other at very minute intervals of time, and the cartridges are fired in rapid succession. In this piece, careful aim can be taken from a moving platform, and at the right Fig. 30 Fig. 31. moment the barrels can be fired at the object almost simul taneously ; they could be made to fire at the same instant,