The objections to the original tin feed ease were that it worked irregularly for different angles of elevation. and that the cartridges did not always fall in their proper position in the grooves. with the consequence ',hat jamming fre quently occurred. The •Bruce Feed' was designed to remedy this last defect. It was constructed on the gravity principle, and consisted of an upright bronze standard to which was attached a swinging piece containing two grooves, beneath which was an opening. which in turn connected with a wheel turning freely on its own axis. In action, the cartridges were fed into the opening f the breech cases above the carrier block, where they became engaged in the grooves of the swinging piece, and passed directly into the fixed mouth, so that as each cartridge made contact Nvith the wheel the latter was made to revolve by its impact and pressure and thus present the next groove for the next cartridge. As the wheel turned round it car ried and deposited the carriages in the grooves of the carrier block ready for discharge. The de vice answered its purpose with regard to the avoidance of jamming, but was as variable and uncertain so far as regards the different angles of elevation as was the old tin ease.
The 'Aceles' feed drum was designed to obviate this difficulty, and as it fed the gun without the aid of gravity, being in effect a positive feeder, it was independent of the angle of elevation.
defect, a feed has been introduced which leaves but a small surface exposed to lire and is in other respects entirely free from the defects of its predecessors. Long strips of sonic cheap flexi ble metal, tin preferably, having tongues or slits (one end of each of the former attached to the strips, while the other is separated, and so sur round the cartridge as to keep it in position on the strip), are fed into the opening of the hopper. The rotation of the crank compels the projections on the grooves of the carrier block acting upon the cartridges to force the strip through the hopper. Tints each cartridge is in turn de posited in the groove of the carrier block, the empty strips being discharged to the right. The Gatling gun with improved feed has attained a rate of fire about 20 rounds a The Gardner gun closely resembles the Gatling so far as regards the principle of rapid fire. It consists of two barrels parallel to each other and The invention consisted of a two-beaded drum, connected by a sheet-brass easing, the heads also being of brass, and the distance between the two equal in length to that of a cartridge. Each head was grooved in a spiral form. The car tridges are inserted in the drum through the month and rest in the spirals and between the radial arms. To fire the gun, the feed drum is inserted in position directly over the carrier block, the opening- of the drum resting over the grooves of the block \dill the planes of its heads in position with the axis of the barrels. The movement or rotation of the crank causes the lock cylinder, barrels, etc., to revolve: and at the same time the groove projections of the car rier block force the radial arms of the drum to rotate. The great objection to this device was that while the feed was perfectly regulated. caus ing no deviations of elevation, yet the weight of the drum was a serious drawback, besides which, a bullet striking its exposed surface instantly put it out of action. To avoid this very serious having their axis in the same horizontal plane. Its component parts other than the barrels are: the casing, bolts, firing, and extracting, mechan ism, cams, and feed valve and guide. The eas ing is of bronze and forms a support as well as protection for the barrels. A current of air is caused to circulate around the barrels by means of two openings made in the top and bottom. The rear part of the easing (box-shaped) con tains the mechanism. The two U-shaped bolts (one for each barrel) have a backward and for ward movement in the casing. The firing and extracting mechanism is both simple and in genious, the feed valve and guide closely re sembling the Bruce guide already explained in connection with the Gatling gun. except that it is without a wheel and is attached to the easing in the rear of the barrels. It is so arranged as to cause the cartridges to drop from the feed guide through the holes in the easing and from thence into the chamber, into which it is forced by the bolt. This action opens the other barrel, which
is loaded in turn, and so on until the ammuni tion is exhausted.
The guns of Class B that are now in use are (1) fully automatic, or (2) semi automatic. A gun is not automatic if it is operated by the rotation of spindle worked by hand, clockwork, or by motor; for the evident reason that the operating power is obtained from an outside or external source. But, if the power is derived from the explosion of a preceding cartridge, the gun would come under the heading of powder gas acting on the lug throws it back with force sufficient to give power to carry on all the operations of loading and tiring. The gun has no water jacket, but the barrel is very heavy more than an inch in diameter). The car tridge: are fed in a belt of woven cotton which carries 250: additional belts may be placed in position with the loss of but a few see, lids' time. The gun used in the United States Navy has a calibre of 0.236 or 0.3o Mph, and weighs 40 to 42 pounds. It is usually mounted on the automatic machine guns, and thus be differ entiated from those operated by a crank worked by hand, or a 'motor machine gun' worked by an electric or other motor. The term semi-auto matic when applied to ordnance is used to denote any gun in which the functions necessary to its employment are performed partly automatically and partly by external agents. The fully auto matie guns may he divided into (1a) those op erated by the powder gas acting upon a piston, and (lb) those operated by the recoil of the barrel or other parts when the piece is fired. All ship's rail or on the rail of a top. For service in the field a tripod mount weighing 50.25 pounds is supplied. The speed of fire is about 300 rounds per minute, but, owing to the necessity of changing the belt. about 250 is the practical limit. The Hotchkiss and Vainanonehi guns dif fer from the Colt chiefly in the method of uti lizing the pressure of the powder gas. Instead of pressing against a vibrating lever, the powder gas escapes from the hole in the barrel into the end of a cylinder underneath and presses back a piston which works the mechanism. As soon as semi-automatic pieces so far produced are oper ated by the recoil of the barrel or moving parts. The fully automatic guns of the la class are vety numerous, but those best known are the Colt ( Browning's pa tent ) , Hotchkiss, and Yamanouchi (Japanese). The mechanism of the Colt gun is driven by the action u f a vibrating lever which is pivoted on the gun and has a short cylindrical lug at its forward end resting in a socket in the easing and covering a hole in the barrel near the muzzle. When the bullet passes `beyond the hole in the barrel the pressure of the the bullet leaves the muzzle the pressure against, the piston is removed and it is free to come forward again and is returned by the action of a spring. The guns of the (lb) type are quite numerous. but the Maxim automatic. Min. the Maxim - Nordenfeldt automatic 1 - pounder, to which the mune of Pompom was given in the British-Boer War (1'399-D021. the Dawson-!-'zil verman (Vickers automatic 3-pounder. and the Skoda automatic !run are well known. in all except the Dawson-S'ilverman 3-pounder the re coiling barrel or breech-lock drives a train of mechanism and the pieces are loaded from a belt; in this 3-pounder the ammunition is placed in a hopper over the breech from which the cartridges fall into place by gravity, when the breech is open and empty, and are driven for ward into the breech' by a lug on the loading types. the Alaxim-Nordenfehlt, Driggs. Arm strong, etc. Of theve the first is by far the best known. It is adopted in the United States Navy and is the only semi-automatie gun used in any naval service. After the gun is tired the barrel recoils, compressing certain springs by which it is pushed to the front again. As it moves to the front the breech-lock is forced downward and the extractors eject the empty cartridge ease and then hold the breech-block open: the loader in serts the fresh cartridge, which trips the ex tractors as it slips into the bore and allows the breech-lock to rise and close the breech ready for firing. This semi-automatic mechanism is applied to guns which are considered too heavy for machine-gun mechanism; in the 'United States Navy it has been adopted for use in 3-inch (13 pounder) and 6-pounder (2.24-inch) guns.