Gun v. Armour.

Te Aroha News, Volume V, Issue 206, 11 June 1887, Page 7

Gun v. Armour.

An important success has been scored on board the Nettle, target-ship, at Portsmouth, in favour of tho defence against the gun. The English service has uniformly confessed a preference for compound, or steel-faced, armour as compared with solid steel plates, for, while steel armour possesses great rigidity, it stars under the attack of guns of light nature, and cracks through beneath heavier impacts, being only held in placB by tho bolts. Compound armour, on the other hand, though it seldom, cracks under the sen ice test beyond tho weld, and pulverises the shot as effectually as solid steel armour, is (says the " Times ") not quite so rigid. It bends slightly under repeated impacts, or, as it is technically termed, "dishes." In order to surmount this defect various expedients have been tried. Mild steel has been used as a backing, while in another instance two steel plates have been sandwiched by a strake of iron. But in these experiments, while bulging has been reduced, tho liability to cracking has been perilously increased, and up to the present time nothing has been found to give such satisfactory results as ordinary iron backing. The plate which has lately been tested for experimental purposes in the interests of the manufacturers, Messrs. CamJ mell and Co. , of Sheffield, was made specially, not only for tho purpose of securing rigidity under attack and resisting penetration under the ordinary attack of chilled projectiles, but of resisting steel shot. This was the first experiment of the kind delivered against compound armour, and great interest was manifested in tho result. The plate was constructed in accordance with a new patent which has been taken out by Mr Alexander Wilson, of Cammell's firm. It measured Bft by Bft, and was of the total diameter of lO^in — a thickness which has hitherto been sufficient to resist the heaviest gun in tho Nettle with ordin ary charges. The face was specially hard ened to withstand penetration, and, in addition to the customary iron backing, ife was further strengthened by a third strake of ingot iron. The plate was also subjected to peculiar treatment known only to the manufacturers. Tho target was first attacked by Captain Domville, of the Excellent, gunnery ship, with three rounds from the lOin. 18-ton gun at a range of 30ft., tho charge being 701b., and the projectile, a chilled shot, weighing 4001b. This, which is the usual Admiralty test for armourplates of the same thickness, represents a muzzle velocity of 1,36-ift. per second, a muzzle energy of 5,288 foot tons, and a penetration of iron of 12.7 in. at 500 yards. The three impacts, which were disposed triangularly, produced no penetration, the projectiles being broken up into small fragments ; and no damage was inflicted beyond some lamination of the steel face. The ordinary test having thus resulted in favour of the defence, the plate was next attacked near the edges by a stoel-forged shell, a steel cast shell, and a cast iron shell, all of foreign manufacture. But, though the armour was taken at a manifest disadvantage, none of the projectiles managed to penetrate, the steel shells being completely broken up, while the cast-iron projectile was actually reduced to powder.