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How the iron plates for the great warThe London ‘"Engineer"’ gives the following interesting account of the process by which the iron plates for the new English war steamer Warrior are constructed: The tests which were applied to the plates furnished by the builders of the Warrior were of the most trying character. Some plates were fired at with 68-pounders, at 200 yards range, and were literally cut in halves by balls, fired one after another, on a line drawn on the surface, each ball striking immediately below its predecessor. Upon some other plates the balls made a circular indentation upon the surface nearly as deep as the plates, exactly of the form of the projectile, and as though a mould had been taken of it in some soft and yielding substance. It was only after repeated trials that it was decided that the plates should be of annealed scrap iron. The labor involved in building up these plates is enormous. In the first instance, small scraps of iron are thrown into the fires, and, when in a state of red heat, are subjected to severe hammering, under the steam hammer, until the whole is beaten and amalgamated into a solid mass of about half a ton weight. This lump is then placed on the top of a similar mass, the whole made red hot, and hammered and welded together. Repeated additions of this kind are made until about five tons of metal are thus welded together in one huge, shapeless body. This is then brought to a glowing white heat and placed under the huge hammer, the thundering blows of which gradually reduce it into shape. Again and again the enormous slab is put into the furnace and hammered into one piece, 15 feet long, 3 feet wide, and 4½ inches thick. From ten to a dozen men are engaged in the work of moving these ponderous masses of iron, which are moved about apparently with the most perfect ease. Powerful cranes swing the molten mass from the furnaces to the hammer; a nicely-adjusted balance is provided by a massive iron lever, one of which is welded into and forms part of the metal, and this is provided with a dozen or more of horns or handles, by which the iron can be turned in any direction; for the plates are not only hammered on the broad surface, but at the sides and at the top and bottom.--The plates, after having been roughly formed into shape, are completely planed and squared. Planing machines of enormous size hug these plates in their resistless arms and bear them slowly and silently under the sharp cutting edges of the tools, and thin shavings of the metal, which, as they are cut off, coil up in long, bright ringlets of iron, attest the tremendous power of hese noiseless and all but omnipotent machines. When the edges and surfaces are made perfectly smooth, like the finest work of the cabinet maker, the plates are placed on an end, gripped firmly by a mortising machine, and as they travel slowly backward and forward in the framework against a small tongue of steel, a groove of about one inch in width and depth is formed, into which the corresponding projections formed on the side of another plate will fit with the most perfect accuracy, the plates all being made to dovetail on each of the four sides.
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