1UKI.KI' OHDNANCK 



ItlFLKD ORDNANCE. 



H 



4^ |a Mcfc fibr* U at flnt newly proportional to the extenaion. 

 Mr. HodgkiuKtt fwund that in cast-iron the reaiatanoe to extension 

 WM le than a quantity proportional to the xtiuion by a quantity 

 nearly proportional to the suuar* of the extenaion. If w represent 

 1 1 sfals rr to extension, and t the corresponding extenaion, te-=ae-lxf. 

 therefore evident that at a certain thickness of uii-Ul the cohesion 

 or tMMtle strength of the inner ring may be overcome, and the ring 

 tmnt before the outer ring receives any strain, ami therefore it is useless 

 to imriexi the thln^m** of metal beyond the puint at which the force 

 TTTrt~* oa the surface of the bore ia sufficient to rupture it before the 

 train acts to any extent on the exterior. With respect to the second 

 point, taking two spherical bullet* of 2 and 4 inches diameter, nttrrit 

 ffr&ut, the pressure required to give them the sumo initial velocities 

 will be as their weight*, that is, as the cubes of their diameter*, but the 

 surfaeaa of the bom will only increase as the squares of the diameters, 

 and therefore with larger calibres the strains on the guns will be 

 greatly increased. 



In order to obtain the requisite strength in rilled ordnance (espe- 

 cially in thie of a large calibre), where the strain in again increased by 

 the resistance to motion offered by the rifling, it is necessary to adopt 

 aaane mean* of equalising the strains through the metal. Different 

 waya of effecting this have been suggested. The object of all of them 

 is to give a certain initial tension to the outer rings the exterior 

 having the gnatost, and the tensions decreasing and resulting in com- 

 praaaiim in the interior. The rings can be shrunk on to an interior ! 

 cylinder or cure, that if, put on hot and then cooled, or they may be ' 

 put .n by hydraulic pressure, or the core or tube may be bound round 

 with wire, gradually increasing the strain of each layer. Captain 

 RUkcly; It. A., who appears to have investigated the subject fully, made 

 a gun in this last manner, which stood some moat sever* trials at Shoe- 

 buryness, in ISM and 1857. The ancient built-up guns, such as Moos 

 Meg. were often made with longitudinal bars, kept together with rings 

 shrunk on. This process was evidently adopted on account of the j 



imperfect state of manufacturing power, ns there could be no use in 

 not having the interior a homogeneous cylinder. A huge mortar of 

 30 inches diameter was, however, made in this way a few years ago by 

 Mr. Mall.-t. and failed. 



In 18M Sir \V. Armstrong brought forward a breech-loading rifle- 

 gun, hig plan was accepted, and a gun of email calibre having been 

 made according to it, was tried at Shoeburyness. With some modifi- 

 cations this description of gun has been adopted in the British service, 

 and found very efficient in the late China war. In fact it is the must 

 perfect gun yet adopted in any artillery. The following description of 

 the original gun tried at Shoeburyness, and at Sir W. Armstrong's 

 private factory at Newcastle, is taken from the minutes of ' Proceedings 

 of the Uoyal Artillery Institution,' given in the ' Elementary Lectures 

 on-Artillery for the Uoyal Military Academy/ by Major Owen, II \.. 

 and Captain Dauies, H.A. ; from which also, and a paper on the ' Con- 

 struction of Artillery,' printed by the Institution of Civil Engineers, 

 the description and drawings of gun, shell, &c , are taken : 



" A core or internal lining was formed of cast steel, to which the 

 requisite strength was given by encircling it with twisted cylinders of 

 wrought-iron made in a similar manner to gun barrels, and tightly 

 contracted upon the steel core by the usual process of cooling after 

 previous expansion by heat ; the parts are then in a state of initial 

 tension, which is necessary to bring their entire strength into operation. 

 The arrangement for loading at the breech consists of a powerful screw 

 having a hole through the centre in the prolonged axis of the bore, 

 through which hole the bullet and charge are delivered into the gun. 

 A " breech-piece " with a mitred face fitting a similar face at the end 

 of the bore, is dropped into a recess, and by the action of the screw 

 pressed tightly into its seat, so as to effectually close the bore. The 

 fitting surfaces which close the bore were at first made of unhanleued 

 steel : this failed ; hardened steel was next used, but this yielded to 

 the action of the powder more rapidly than before ; copper was then 

 tried, and no further difficulty was experienced. The breech-piece 



I. Armstrong Gun, scale j inch to 1 foot ( T y. 



contain, the vent. The bore of the gun was If inches in diameter, 

 and contained eight spiral grooves, having an inclination of one turn in 

 IS feet ; these grooves terminated at a distance of 16 inches from the 

 breech, and the bore then gradually expands in a length of 3 inches 

 from 1J inch to 1] inch in diameter." The gun weighed about 

 . 



The projectile, which is cylindro-conoidal in form, was 6J inches 

 Jong, and weighed 5 Ibs. ; it was of cast-iron coated with lead, and was 

 hollow, to as to be used either as shot or shell. It was slightly larger 

 la diameter than the bore of the gun, and being inserted at the breech 

 took it* rifling by being forced through the grooved bore 



Tbecharge was one^ighth weight of shot. The following results of 

 experiment* are given in the ' Lectures ' before mentioned : Fourteen 



""^fc^" !77 *,* b o? f wood 6 feet wide and 7 * hi g>> f 



adtttance of 1500 yards. Six shots were fired as trial shots to obtain 



wrrert elevation. The remaining eight hit the butt without 



C^ t ^ f ^ t> f . Ule P" 1 bein B 4 * 26> - and tl>e mean deletion 

 bom the centre line on the butt was only 111 inches. The experiments 

 w.th .hells fired at two target,, placed 30 feet apart, covering one 

 ^^Z'TT* ?? "^"We-nearlyall the she\ls passing through 

 Ihefirst target and bunting before reaching the second 



toga small gun was of course easy of manufacture, but Sir 

 W . Armstrong baa been equally successful in making 12, 25, 32, and 



is to say, the sides the projectile bears on in passing out of the gun, 

 are cut square, or at least radial, the other edges are rounded off. 



rbel2 pounder is the gun adopted for the field batteries and horse 

 arUllery. Those ted in Ch.na have weighed 6 cwt., with a charge of 

 lh fh% l n rob ' blC , U "i w f " ture " 8 cwt. gun, with a charge 



adopted. The guns are now made wholly of 

 Hfbt iron, and m ordtr to avoid the difficulty of fo 



wuTJ^hT "EV? pi T*- ^ from 2f * 



oVZ.Ll ^ OUl f r ' T, betl i b<M<lro formed y wn., 

 heated u-on round a roller, the coil is then brought to a 



^l^TJf'T 1 ??*"'' the - 1 "" of the coiU ^be 



been bevelled off, the tubes are welded together. The manu 



facture >. very complicated. The finirted gun is 



Th. groove, are very narrow and shallow. Th 



Fig. 2. Armstrong Shell, scale j. 

 The width of the lands and grooves being the same, they vary in 

 number according to the calibre of the piece, the 12 pounder has 



