ARTILLERY AND-IRON PLATES.

Otago Daily Times, Issue 180, 25 June 1862, Page 5

ARTILLERY AND-IRON PLATES.

The most important experiments with iron plates which have been m.ide since the introduction of armour into ship building, havo taken place at Shoe- , bnryne.'s, when a target made in exact imitation of the Warrior was smashed to atoms by a new gun, which was then tried for the first.titne. We take from the.Times an account of the proceedings : — During the course of all the experiments at Shoeburyness it has been noticed that the injury inflicted upou.the iron plates by the old smooth bore GS-poun-der was greater than that effected by the shot from the riiled Armstrong 110-poundcr. The cause of this apparent superiority of the old gun wns due to the heavier charge of powder, and therefore to the initial velocity, or, in plain terms, the speed with which the old spherical missile left the mouth of the cannon. With the Armstrong gun the velocity of the shot is from 1150 feet to 1200 feet per second, .With the old smooth-bore muzzle-loaders the velocity is, as nearly as possible, at the rate of 1600 feet per secoud, or more than one-fourth greater. But the important difference between the two kinds of ordnance is, that the old smooth-bore gun after 500 j yards loses its velocity, owing to the resistance of the I air, with alarming rapidity, till at 3000 yards it ! tout'has the ground, while, on the other hand the cor'cal form of the Armstrong shot, and the rotory motion communicated to it by the rifling, enable it to maintain almost its initial velocity over a flight of 7000 yards, or even more. Tims it is that if the Armstrong and the old smooth-bore gun are fired at the si'-ne instant, the shot A-om the latter is instantly ahead of the rifled projectile, but at 700 yards their velocities are the same, at 1200 yards or so the rifled shot is ahead, and at 2000 or 3000 the old shot has mide its graze against the earth, while the Armstrong is stiil in mid career, and can strike with four times the force of the CS. But when firing at the iron targets.at short distances two massive shots, one travelling'l6oo feet a second and the other 1200 have each to be stopped dead in the fractional paio of a second, and it therefore followed, as a matter of ci.'Ui-se, that the projectile going the fastest inflicted a damage exactly in proportion, to the velocity of its flight and tiie charge with which it was propelled. At close point-blank ranges, therefore, the old smooth bore li.S-pijiinder was,-weight for weight, more destiuelive to iron plates than the 110-poundcr ArmsLroog.

it: hits, therefore, been ohought that wrought-iron giios uf largo calibre, and strong enough to stand the heaviest shot and heaviest charges, would, at close range,' easily penetrate any thickness of iron plates tiiat a. vessel could safely venture to sea with, and the experiments of Tuesday afternoon proved the truth of tha conjecture. Sir' William Armstrong has niade a 300-ponnder on his own admirable principle of \viou--lit iron coils. This gun is about 14 feet in Jeng.ii, its weight is 12 tons, and its diameter at the rmizule lO.\ inches. It has not been rifled, and, therefora, during tho experiments of Tuesday, it only threw round solid shot of loGlb. weight. If rifled for tho Ai aistrong shot, which is about two and a 'half tiaies the length of its diameter, it would be a 800-pownde:1. This gun, unrifled and with plain shot, was tiied against that great champion of heavy weight which has hitherto come off victorious in all euemi(>l;prc—the redoubtable Warrior target. His Royal Highness the Duke of Cambridge, the Duke of Somerset, the Duke of Sutherland, Lord Clarence Paget, Admiral Grey, Commodore Druininond, Capt. S:r J. D. Hay, Captain Hewlett, Captain Yelverfcon, Mr. Fairbairn, sen., Mr. Laird, Mr. Samuda, Sir Wiliiam Armstrong, and other noblemen and gentlemen connected with the War Office and Admiralty," or intorsated ii the success of artillery or iron ships, were present; though, on the whole, the attendance was small, and the experiments were conducted with en usual privacy. T-ho great interest was concentrated on the effect of the first shot. With the high speed which our Warriors s>~e known to possess, and thec-'ore the quickness with which they can steam pn"4 batteries-or iron ships, it was reasoned, with perfect truth, that it was next to impossible in a running fight that they could be hit twice in the same place. If tho target kept out one shot, there was every hope of a ship keeping out all.; The first shot, a ]66 pounder, was lived with a charge of 401b of powder, at :i distance of 200 yards. This solved all double. With an indescribable crash, that mingled feiirfe'ly with, the report of the gun, the shot struck upon a comparatively uninjured 2)iate, shattering the iron mass before it into little crumbs of metal, splintering the teak into fibres literally as small as pins, and, though not passing quite through the side, yet bu'jiugVind rending the inner skin of the ship in a way that would have rendered it almost impossible to stop the leakage. The second shot (still with a forty pound charge) struck close by the first, making the previous damage tenfold .worse, if possible. To those who did not actually seethe experiment it would be

difficult.to describe the manner in which the iron oppo that it more resembled tangles of fine twine than even the remains of woodwork; and how, above all, the inner-iron skin was ripped into gaps like torn paper. These two shots were quite conclusive as to the power of the gun. Had they struck an iron frigate at the water line, no means could have prevented her from sinking in half an hour. Still, however, the' shot had not'gone completely through the side, which it was the great object of the experiments to accomplish. The charge of powder was, therefore, increased from -10 1b to 59 lb., and the gun levelled at the uppermost plate of the target, which had been left untouched in previous tests. On this plate a white spot was painted to gii'de the artillerymen, and so true was their, aim,—so exactly was the centre of the mark struck,- that every 'vestige of the paint was obliterated. With this increased charge the shot passed, not only through, armour plate, teak, and inner skin, but buried itself in the massive timbers tlmt supnori. the target, and even loosonoi the ( blocks of nran its by which the whole is backed up. Had it been the side of the Warrior against which this | imbai'e was directed, it would not only.have gone j throivh the side, but nearly through the opposite j side as well. Another white mark was then made on Hie lowest plate of the target, and again the artillery men hit it with the same marvellous precision and with Ihe same result. The shot went through everythi.)", and even the fondest believers in the invul-. nerability of our present iron sides were obliged to cmfess that against suck-artillery, at such ranges, their' plates and sides were almost as penetrable as wooden phi os are now to the plain old-fashioned long 82's. Of course, after such decisive results, no further experiments were tried ; indeed, they could not bs as the 150-pounder evidently thought it had done enough work for the day, and at the last discharge r, 3Ci>;fed so much as to get off its wooden platform aid imbed ths hind wheels of its carriage in the stift vot watery clay, for the production of which in the :a'ves6 quantities at the shortest notice Shocburv.iess slant's unrivalled. But quite enough had beeii accomplished, and admiralty officials and armour _ shipbuilders could only admit to each other in a Hud of confidential dismay, that artillery had at last proved too much for them, and that if invulnerable ships were to b3 constructed they must begin de novo. ' The Warrior, Black Prince, Defence, and llesistance—the only four armour frigates which we have yet afloat—are coated with4J inch plates of iron, wiui Wo layers of 10-inch teak beams placed transversely, and with an inner skin of n /ought iron nearly an men thick, ft was against this powerful, combination of male ills that the 156-pounder gun was tried on Tuesday with such complete success. The now frigates bu-'din", the Achilles, Hector, Valiant, Agmcourt, Northumberland, and Minotaur, are all to be coated with SJ-inch iron plates, with 10 inches of teak, ami the same inner skin of wrought iron. In these it is hoped that reducing the teak backing and increasing the armour plate will add to the strength ofthe ship ; but long, very long before these vessels are launched the present 156-pounder will be rifled to throw a 300----pounder flat-headed shot, against which-not six or even eight inches ot armour may be able to otter resistancl at short ranges. What, in fact, is to be dono whan-we are at the same time exerting, our efforts and spending our money to construct indestructible ships and invent irresistible guns? Tho guns must carry the day. We have nearly reached the limits of the thickness of iron plates which sea-going vessels can carry with safety. There is practically no limit to the size of the coiled wrought-iron gun. To-day a 156-pounder wins-a month hence and the sarae gun will be a rifled 300-pounder, and a 600-pounder may be ready before Midsummer; but with thicker than 6-inch armour plates no sea-going vessel can be coated. The Americans are now making two *rought-ion puns, unrifled, each to throw a 1,100-pound shot When we Let such results with a plain 156-pounder, what may not the Federals expect to accomphshwitji gigantic ordnance of this description ? Armour, plates I foot thick would be destroyed by the blow of a wrought-iron 1,100-pound shot fired at short range. The utmost promptitude has been displayed by the Government^ experimenting at Shoeburyness upon all new inventions connected with artillery and armour TiHiin" It may surprise our readers to learn that even the construction ofthe Monitor has not escaped their vigilance. A section of it has been erected and nrd atat Shoeburyness, and proved to be as vulnerable a'most as timber, even to our commonest muzzle-lo-idins auns. Even now, that no chance may be neglected* a target is being made of railway bars dovetailed and rivetted together in the same ingenious manner as the coating ofthe Merrimac, and this also will bo tried in a few days, and beyond a doubt_with much the same results as attended the trials at the Monitor target. ■ . '.'■. ■