GUNS V. ARMOUR-PLATE.

Pukekohe & Waiuku Times, Volume 5, Issue 141, 4 February 1916, Page 4 (Supplement)

GUNS V. ARMOUR-PLATE.

THE DOCKYARD'S gjNENDiNG WAR.

Omitting submarines, torpedo, and aircraft, na\al warfare consists of a test between guns and armour-plate. Offensive and defensive powers —embodied on the sea in the naval gun. its platform, the .ship, and armour the opposition to the guns—is, indeed, the essence of all war. Lord Armstrong, llie inventor of the breach-loading weapon which bore his name, declared that in the contest between .."ie.se offensive and defensive factors, the gun would always emerge superior. Given the gun, the plate can be four ' which will resist it; but given the plate., the gun can certainly be made which will smash the plate. There are limits to the developments of plates which do not apply to the gun. The naval architect who presides over the appointment ot the powers of offence and defence to a ship must call a halt to the increase in the thickness of armour, inasmuch as its weight affects the designs of tho ship. The stability of tiie vessel overrules all other considerations; hence the limit to heavy armour. Experience in the present war has emphasised more than ever the absolute supremacy of the gun. It has been demonstrated both on land and sea. No forts have withstood the fire of tiie Krupp siege guns; and although naval experiences have been less, the gun has nevertheless proven its supremacy. The tremendously extended ranges at which actions are fought—seven and miles—with the consequent increased curved trajectory of the projectile, obtained by greater elevation of the gun, have diminished the value of tide armour. The protection of the decks is of more importance. Other considerations, of which we may not speak, here, point to the correctness of a theory held by a certain school of opinion before the war that the chief value of armour-plate was the stiffened 'morale' which it gave the men. They imagined i they were safer behind armour. I

AN OLD STORY. This competition between the gun and expedients on warships to resist its effects goes back to distant days. It has been a prolonged struggle with success sometimes on 0110 side, sometimes the other; but with the gun in the end always demonstrating its supremacy. The floating rafts, or pontoons, which were employed at the siege of Gibraltar a century ago, are said to have had thin iron plates. The notorious privateer Alabama, which made ducks and drakes of American commerce, and involved Great. Britain in an indemnity of over £3,000,000, was finally sunk by a ship which was said to have adopted the plan of throwing heavy chains over her side in preparation for the fight.

As all veteran Clyde-workers know, the first armour-plate warships introduced into the British Navy were the Warspite on the Thames and the Black I'rinee, whcli was built at Napier's Vard. Govan, in 1862. In those days ordinary steamships were wooden buiit. The Clyde produced most of the early Cunarders, and these were wooden vessels. Such a violent departure—the loading of a vessel's sides with iron plates 4iin. in thickness, combined with her heavy guns—convinced many Clydesiders that the " theorists " —as they delighted to call the "high held yins"— had perpetrated some tragc blunder this time. Among the crowds which gathered on the river to witness flie launch of the Black Prince was a sceptical element assured of seeing her despatch—to the bottom. No doubt. 1 ke mo-t pessimists, they felt, sorry when their prediction failed to materialise. THE GROWTH OF ARMOUR. The only material available then for ''armour" was wrought iron. This possessed no great resistive power, and •iiin. on the Black Prince proved of little; service. As a consequence the thickness of armour plates on warships developed rapidly. Designers were urged at all costs to counter the effects of the gun by providing massive iron plates on the sides of lite battleship. Thicker and rtill thicke. - plates were demanded. The climax to this development was reached in 1881. The Inflexible came for*h then as the last word in battleships. This vessel played the leading part in the bombardment of Alexandria in 1882. and was regarded as the Queen Elizabeth of her day. She was equipped with guns of 80 tons —as lug as those on the "Lizzie," and was protected by side armour almost double the thickness of that on the Queen Elizabeth. But the necessity to protect the ship in this fashion involved the designer in profound complications, from which lie emerged by a unique compromise. He designed the vessel with engines, gun turrets, and all vitals within a "citadel," which extended to only 50 per cent, of her length. This citadel was converted into a fort. He placed armour 24 inches thick on the sides, and transverse, across the ship, he ran two belts of armour of 11 inches. This novelty was decribed as the "citadel" t\pe. The idea was that ii the unprotected ends were r.hot away the c tadel lyould remain afloat. Inside the unprotected ends were placed GOO tons of cork to assist in the preservation of stability in the event of their perforation.

Every new design in battleship construction brings its criticisms and answers. Many naval experts in England condemned the "citadel," alleging that if tl • ends were penetrated by gunfire she would turn turtle; while the French Navy essayed to take advantage of this defect by installing a large number of small guns in their ships, the object being to perforate these unprotected ends. And so the Indexible type was never repeated. Nevertheless the object lesson which this freak in design conveyed was not lost. The iron armour plate was doomed. THE END OF THE BIG GI N. At that date both artillerists and armour plate experts were ptocecding on wrong sc enlllie lin s. The artillerist thought only of increasing the eali-' lire of his gun. He did not stop in I: s craze for big guns until he reached the lGJ'n. weapon (larger by I'Jn. than

the Queen Elizabeth's) which was introduced in the Ben bow, one of the old i Clyde flagships. This gun, constructed on primitive scientific ideas, weighed 110 tons. It was very short; it ! speedily developed the defect of drooping at the muzzle, and was of poor serI vice. That sounded the death-knell tithe big gun. Like the Inflexible, which had sent the armour plate manufacturer to revise his methods of production, the Benbow obliged the artillerist ' to retrace his steps and consider better j methods of gun construction. Progress began in.mediately, and has not ceased ; even in our day. 'Developments of the | most extraordinary character, acliievJ ing undreamt-of results, were made. I Consideration began of the metallurgii cal side of things. The armour-plate ! manufacturer set about looking for ' some improvement upon wrought iron 'as a material; the artillerist experi- . merited al~o with materials and better methods of making a gun. A PARKHEAD DISCOVERY. I A first stop in the improvement of armour produced a composite ste >1 p'ate. This was a plate of hard steel I supported by a plate of mild steel. A j later idea was evolved by iiliam ■ Beardmore, of Parkhead, who had be- . gun the business of armour manufae--1 ture, of fusing together in alternate ; layers hard and soft plates. The idea was this. An outer face of great hard- , ness, capable of smashing up a projectile, must be obtained; to that must be given also a tough res.lient backing to absorb the concussion. A plate of universal hardness throughout would ' smash like a plate-glass miror. The ideal armour plate must be so hard on the surface as to smash a project.le. and be soft or tough behind, so as to aiworb the "shivering" effcts of the impact.

Next came an American process —the Harveyised nickel steel plate. Here tlie metal nickel was added to the composition, which gives greater strength, hut the essential development was the introduction of the process of "cementation."' or face-hardening. To the nickel steel was added l>y absorption in heated furnaces a percentage of carbon, which penetrated a certain depth into the plate. Every workman i ri aware that without the presence of a certain percentage of carbon he cannot get an edge on a tool. The steel weak in carbon will not temper. From this plate with the high percentage of carbon a surface of tremendous hardness was obtained by tempering with sprays of cold water. The hack of th plate remained soft and resilient. '1 his Harvey plate was so successful that nint. inches of it equalled in resist.ve power no less than twenty-four inches of wrought iron. The naval designer was now furnished with a material which at almost one-third the weight gave him as good a plate as that on the old Inflexible. Th s revolutionised the design of battleships. There was 110 more plating of a vessel for only parts of her length. An entire belt was now available. THE GUN RESUMES THE MASTERY.

For a time it looked as though the armour-plate manufacturer had won the day. The artillerist had now abandoned his absurd 10-inch guns, and was working patiently at improving a i2-inch gun. He had adopted the method of building up the gun in a series of tubes shrunken 011 each other, and of wire-winding the inner tubes under great tension —wire being capable of withstanding enormous stra n. Later the metallurgist added nickel and other ingredients to the steel, and so developed its strength enormously. The chemifit came forward also with a slowburning powder, the effect of which was greatly to increase the power of the gun. Th's discovery permitted of the explosive yielding up its gases, not all of an instant, but gradually, as the projectile was travelling along the tube; and these were evolved until the maximum pressure was attained as the projectile was leaving the gun. By this means a vastly increased charge of explosive became porsible, and the velocity of the projectile was correspondingly accelerated. The largest gun was, however, st 11 12 inches in calibre. Later developments, in view of the improvement in the slow-burning charge, permitted of tlie lengthening of the gun. Early weapons were 110 more than 3") calibres in length—that is, 35 times the bore of the gun. 35 feet long in the case of a 12-inch bore. The length as developed to 40 cal brcs, then to 45. and lastly to 50 calibres. These developments'likewise brought about enormously increas ng striking energy. The gun again resumed its mastery over the plate. PARKHEAD AGAIN TO THE FRONT. The last step in the perfection of armour plates was introduced by Krupps. Instead of soaking the plates in .1 iiirnace between layers of carbon they introduced gases charged with carbons, and in this way produced, after tempering, a better hardened surface. Messrs. Beardmore and Co., of Glasgow, also developed the manufacture of p'ates, the process of which is maintauied as a secret, and they succeeded in even bettering the Krupp plate. Theirs is the last word in armour plate. It was at least four times as good as the old wrought-iron deA modern battleship carrying 13A inches of this plate was as safe as one with feet of solid wrought iron 011 her sides. Compared to the present-day plate, that of Jit teen or twenty years ago is as cheese to iron. It may be interesting to the public to indicate that these modern armour plates possess a surface so hard that it is impossible to mark it by a bhnv from the heaviest hammer delivered on a steel punch. Belore be ng passed by the Admiralty, sample plates are tested before the gun, and the slightest appearance of defects entails rejection of the lot. There is 110 escape for a defective batch of plates, such as the Russians discovered in some of their ships during the Russo-.lapanesc war. In the days of their production, however, armour-plate makers were