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With guns of luge calibre whciv (he bmrh -block in 

 of great weight, ii i. turned, pulled nut und drawn to 

 one side by hydraulic, pneumatic, or steam power. The 

 charge of powder u fired by means of a percussion 

 primer which is struck by a spring lock, pulled from a 

 distance of several feet by a string or laniard. 



A section of a breech-block is shown. The charge 

 ruts against a mushroom -shaped part, with a stem 

 running through the block proper. To prevent the 

 escape of the gas past the block a gas-check, or 

 obtunttrur, is employed. This consists of a linen 

 collar (C), filled with a mixture of 65 per cent asbes- 

 tos ana 35 per cent, mutton suet, fitting snugly around 



Oat-Check. 



and iust under the movable head. The collar IB en- 

 cased and protected by steel rings, maintaining the 

 form of the plastic material. When the gun is fired 

 the pressure upon the movable head is transmitted to 

 the gas-check, which is forced <>nt airainst the sides of 

 the chamber, causing perfect obturation. The second 

 method uf closing the breech, known as the Krupp 

 meehanism, is on the wedg_e plan. The breech of tne 

 pin is extended fora considerable distance in rear of 

 the chamber, and a hole is cut through the gun hori- 

 zontally, in which slides a cylindro-prismatic. or Q- 

 shapcd breech-block. The plane face slides across and 

 closes the end of the bore. On this lace a shallow 

 circular recess is cut, and in it placed a thin disc of 

 copper, over which is a steel plate. Against this| 

 presses a steel _ring, with annular grooves at the back. 

 which, expanding against the steel face of the plug and 

 the walls of the bore, prevents the ex-ape of the gas. 

 This wedge is a modification of the invention of Mr. 

 Broadwejl, an American, and the gas-check ring is like- 

 wise his invention, and is called tne Broadwell ring. 



Mortars are short, heavy pieces of ordnance, with 

 large bores, throwing shells at high angles, so that they 

 may fall upon an enemy's ship or into his forts, and 

 other places that cannot be reached by horizontal fire. 

 Howitzers are light .-shell guns firing large projectiles at 

 low angles with small charges of powder. They are 

 made both Booth-bore and rifled. 



Machine-guns, while not strictly coining under the 

 head of pfdauee, will be descriU'd. These are guns 

 with which rapid service is obtained by having the 

 projectile and p. iwder charge put up as a cartridge, so 

 that they need not be loaded separately. They are 

 termed machine-gutm, revolvim: cannon, and rapid-fire 

 gun*, the di-tinetion between the first two and the 

 rapid firing nun being the s.ime a* between a revolver 

 or magazine-rifle and a single-barrelled breech-loader, 

 which mn-t be loaded after every fire. 



' are cast either solid or hollow ; in the latter 

 case cooled from the inside, and are then turned to the ; 

 proper IDftpe on the exterior and bored. The terms! 

 bout-lip and " hoooed " arc applied to guns; 

 wberan the gun is made in parts whicn are afterwards 

 united by ihnnking one part on another. 



1 be l.iie-t English guns as well as our own arc built 

 on the >y,t. -in o| .Mr. J. Vavasscur, of England. The 

 gun i* couipoMcd of an inner tube of M. el :is thin a* 

 w consistent with Mrcngth. having a long jacket shrunk 

 "ii to provide' longitudinal strength, with layers of MI- 

 penmpoeed cylinders or hoops shrunk on, the number 

 varying with the *ir.o of the gun. The general method 

 of procedure us as Mows : 



The gun-tube, jacket, and hoops are obtained from 

 the steel maker, accepted only after the most rigid 

 tests, rough-bored and rough -turned. The tube is 

 turned to nearly the size required for receiving the 

 jacket, then temiKTcd in oil and then turned to the 

 proper finish. The tube is then placed veitieal in a 

 pit. muzzle down, and water is pumped in to keep it 

 cool. The jacket is then raised to a red heat, lifted 

 from the furnace and lowered over the tub.-. ( ias and 

 water jets are employed for hcatim: and cooling such 

 portions as require it. When cold the gun is put in a 

 lathe and the jacket turned for the first layer of hoops, 

 and these are shrunk on in the same manner as the 

 jacket, and after cooling are turned down for the next 

 layer, and so on till all are in place. The gun is then 

 finish-bored and ground, the trunnion band screwed on, 

 the l>orc turned out. rifled, and the breech-screw cut. 



(Inns are also made of east iron bodies with Drought- 

 iron and steel bands shrunk on to strengthen them. 

 I'a.-t-iron smooth-bore guns have been converted into 

 rifles alter various systems, the principal being those 

 of Major 1'alliscr, of England, und of Mr. Parsons, 

 an American. In the former, alter the gun has been 

 bored out, it has inserted from the muzzle a tube con- 

 sisting of two thin wrought-iron barrels, the outer a 

 short one shrunk on at the breech end. The end of 

 the tube is closed by a solid wrought-iron breech-screw. 

 The tube is held in place by a screw-locking ring at the 

 muzzle and a .screw passing through the cast-iron just 

 forward the trunnions. In the 1 'arsons method of 

 conversion the tube is made of steel having a solid 

 breech, the tube being reinforced by jackets of steel 

 shrunk on, the whole inserted from the rear end and 

 a plug screwed in behind it. 



Shell are projectiles tilled with an explosive, such as 

 gunpowder, generally fitted with a fuse which is 

 intended to ignite the explosive. Fuses are arranged 

 to explode the shell on striking or else are time-fuses, 

 whereby, by means of a slow-burning composition which 

 i- set on lire by the blast of the gun, the time of explod- 

 ing can be regulated. In spherical shells for smooth- 

 bore guns a wooden sabot or block is fastened to the 

 shell by iron straps so that the fuse is kept to the front. 



Various methods have been employed to impart ro- 

 tation to projectiles. Studs on the shell projecting 

 into the grooves of the bore, lead coating, flanged 

 rings on the base of the projectile, and the section 

 of both gun and projectile made hexagonal, as in 

 the Whitworth system, have all been tried. The 

 best practice at present gives rotation to the projectile 

 by means of a soft coper band forced into a score 

 sh 



near the base of the shell, projecting about .07 of an 

 inch beyond the sides of the shea. This band is 

 forced into the grooves of the gun as the projectile 

 passes along the bore. 



Ca.-t-iron shell are at present being made at the 

 Washington Gun Factory for the new naval guns, but 

 determined efforts are being made to manufacture ea-i 

 steel shell. Chrome-steel forcings have been found 

 sati.-faetory for ti-in. shell. Abroad forged and tem- 

 pered steel shells are made which pass through armor 

 plates or rebound with but little deformation. 



Besides shell, guns lire case-shot, or a collection of 

 small projec! d in a ease, the principal case- 



shot being grape, canister, and shrapnel. Shrapnel 

 are thin-sided shell containing a small burning charge 

 of powder, around which charge are placed a number 

 of small balls embedded in sulphur. A grape-shot is 

 composed of a number of small shot arranged around 

 a spindle and held in place by discs. A canister is a 

 metallic cylinder filled with balls, closed at the ends 

 with wooden or metallic discs. The balls arc packed 

 in ro.-in or coal-dust and for smooth-bores in saw-dust 

 were lir.-t used by the Kngli.-h at the battle ot 

 Werewater in lo'JT. In 1346 guns were used at the 

 battle of Cressy, where, guns being unknown to the 

 French, the English were victorious. Portable fire- 

 arms arc supposed to be the invention of the Italians 



