THE BIG GUN.

Taranaki Herald, Volume LXII, Issue 144360, 26 March 1914, Page 8

THE BIG GUN.

HOW IT IS MADE. Emm the old-fashioned cast-iron gun witfi a range reckoned in lect to the great gun or modern times with a range ol' miles is a lar cry, but the results of expcrinients (jy seieiiliiie men ol all nations during tno past HM) years luivc given ns to-day what is practically perfection in the art of gumuaking, says tlie Philadelphia Record.

Over 100 years ago guns wore cast in solid iron or a combination of bronze and iron, and were always liable to explode if overcharged, due not to any fault in the material, bur chielly to tho fad that they were cooled irom the outside, and in consequence when tho gun was fired the inside or Imre would explode quickly, cracking the whole piece. A later method was used by which tin* inside was cooled first, and solidifying, was fompre.wscd and supported by the contraction of the exterior when il was cool;d down. Still Inter a system of building up guns was devised u beroi>y each portion of the metal was made to bear a fair share ot the strain.

I Nearly all big guns are now entirely ! ol steel made l y the open hearth prol cess. Months n:v required to buit-i up i one of these guns, which aiv'conI stnu-K-d in Mvtiom: —i.c., the liner or ! barrel, the jackets which lit over the ! breechblock which closes the opening i tnrough which tite projectile is thrust. ; ’The jackets add extra strength ui : Ilu* portion .of the. gun in which the explosion takes place The composition : of 1 lie metal vanes little, the greatest ! care being taken fa produce a me J M | free from bubble,-.. ! After the ingot is cast and cooled it is removed to a large furnace heats*! by g;u> or oil. securely bricKcd in so that very little heal is lost, and sub--1 jeeuil to 1 steady (lame, which gradually ’’eats it to the ctntre. It i.» tin 11 lakon to a pr»s-. with a pressure of ’jt.oAi tons, where from a great olock it i- by degiecs reduced In a Ion;; bar alcnr sixty feet in length and two tern in diameter. Jins ih d<me w!n!e ' luc ni 'al in hot.

p’rom the prerfi tlm forging, as it inow know*., goes to tho wood anneal ;ng. wb. r<* it is given r ball: 01 fir;

(:it:r**ly o? wood, .tn<l brought (pncr.lv 1., a !dgb »emj;*. rd ore. ’));(•> lemperaruio is lich{ seme tirue. after witich tho Ic-ging eeoU ?tmvly in air.

Tile forging next goes to the machine shop, where il is placed upon a •at ho and re<wives its liiv.i nmgn in;'-

over the out.dde. It is than bored «o the proper -u'.e on a bor;ng b. Ins The bormg, is a nuttier of weeks, and the boring bar one:' >:arted requires id lie attention other than the changdig of (In-- cutters on the end: •veg'-r pinning through tic bar tluslie-v out the cbi|>e and keeps the cutters

.rom heating. "When the forging is known ns a liner. a»'d removed to the oil anneal-

ing ;bop, wlrnr- d is stood upright in a f ;:ni;io‘ r 1 id made hot with nil mimes. M’liile hot il is slowly lowered Tdo a pit of oil and alk'-v M d» cool. Absorhijig the oil the metal beromes vorv louglg allowing it to expand but little when i ; lU<l with the gnses which force the proj«'ctiles cut. Mack again to the machine shop it goes, where it vs machined to the true size.

Tho jacket,•> are made aed treated in exactly the same nmnne.”, with the exception of the o : l hath. When tho parts ere ready thov are carefully lifted together ami hound with hoops of bronze or copper. Tho breech of a gun is the mod important part, for unless it fits perfectly the gases will leak, causing hack firing. Nearly all guns are rihed to give greater accuracy in liriag. Rifling is n system of grooves in live surface of the bore which gN'cs a rotary motion to the projectile, which revolves while passing through the air. thereby lessening the resistance.

'The eompletixl gun is thoroughly i>olislmd bv hand, the muzzle closed with a wooden block, the whole gun oiled t-o prevent weather damage, and shipped to the nmving grounds to he tested bv the Government, If up to the ivnuirouienls it is accepted and goes to heii) make up the armament of a battleship.