Owing to the delay in putting this report in press, after being submitted, consequent upon the large amount of congressional proceedings taking precedence of it at the Government Printing Office, I am enabled to add the results of the first firing of the S1-ton gun at the target at Shoeburyness. The target against which this gun has been proving its powers is the most formidable of any hitherto fired at. It is gigantic, even in comparison with those fired at by the 100-ton gun at Spezia, hereafter to be noticed. Its construction is beautifully and plainly shown by illustrations giving front elevation, horizontal and vertical sections, with accompanying figures and explanations, in the Engineer of February 2 and 9, and from which the accompanying figure has been taken. The target is altogether different from the Spezia targets, as may be seen by referring to the sketch. It is composed of four iron armorplates, each 8 inches thick, sandwiched between three layers of teak each 5 inches thick, amounting in all to 32 inches of iron and 15 inches of teak. The plates are 16 feet in breadth by 10 feet in height. Each plate weighs 23 tons, the collective weight of iron being thus 92 tons. The plates are secured together in pairs by bolts; that is to say, the front plate is bolted to the second one, the second to the third, the third to the fourth, and the fourth to the horizontal beams in the rear. The bolts employed are 3 inches in diameter. The shank of the bolt has the Palliser projecting screw-thread on it, while the head is made on the balland-socket principle, with the hole in the plate allowing play round the neck of the shank, so that one plate may move slightly on the next without shearing the bolt. The target is supported by a heavy frame-work of beams, mostly 14 inches square, and very firmly secured to the ground by strutted piles at the ends, and weighted with an old armor-plate on the top to keep the teak filling from escaping under the force of the blow of impact. The cost of the armor-plates and bolts was about $24,300 in gold, and the cost of the timber and labor about $1,000 more. The first shot was fired February 1. "The gun was charged with 370 pounds of powder, cubes of 1.5 inch, and a Palliser projectile filled with sand to 1,700 pounds' weight, including gas-check, and plugged. This projectile was of service-form, having an ogival head of 14 caliber radius. By reference to the cut, it will be seen that the projectile buried itself into the target, having penetrated through the first three plates and the three layers of wood, also about one inch into the rear plate; that is, it penetrated through 24 inches of iron, 15 inches of teak-wood, and was arrested with the point one inch into the fourth plate, thus leaving 7 inches of iron in front of it unpierced, which iron, being cracked and bent, would offer greatly diminished resistance to further penetration-the projectile itself being split. The horizontal beam at the base of the back of the target was crushed and split into ribbons, and the whole target-structure sprung and shaken. On the same day, a blind common shell was fired from the 81-ton gun at an old 8-inch unbacked armor-plate, which was completely demolished, being split and broken across and thrown out of its position, and the shell broken up and scattered. Doubtless the common shell from this gun would be terrible against any weak-armored ship." MOTIVE MACHINERY. The machinery was constructed by Messrs. John Elder & Co., of Glas Each screw will be driven by an independent set of compound engines with three vertical inverted cylinders of the collective power of 4,000 horses, giving an aggregate power of 8,000 horses (indicated) for both sets of engines. The diameter of the high-pressure cylinder is 70 inches, and the diameter of each low-pressare cylinder is 90 inches; the former is placed between the two latter. They are steam-jacketed and are connected together by stay-bolts continued to bulkheads, so as to serve as ramming-chocks. The pistons have a stroke of 4 feet, and the number of revolutions expected is 65 per minute. The piston. rods are double, and are connected by crank cross-heads. They are each 7 inches in diameter, the connecting-rods having a diameter of 9 inches and a length of 7 feet 6 inches. The valves are of the piston kind. They are worked by link-motions and levers, and are reversed by an ingenious combination of steam and hydraulic power. The engines at starting are assisted by auxiliary steam-gear, the valves of which are fitted to the receiver. The steam from the lowpressure cylinders is exhausted into independent surface-condensers, having a total cooling surface of 16,000 square feet. The steam is condensed in the interior of a series of tubes of 3-inch external diameter, of which each condenser has no less than 6,650. The condensers are constructed to be worked as common condensers. The circulatingpumps are actuated by separate engines, each having its own feed, bilge, and air pumps, worked by levers from the cross-heads. The air-pumps are made of gun-metal, with a diameter of 34 inches and stroke of 2 feet 3 inches, the water being discharged below the armor-deck. With respect to the centrifugal pumps, it may be mentioned that they are judiciously placed at so high a level in the vessel that in the case of leakage occurring, by which the ship's bottom may be flooded to as great a depth as 12 feet, they can be worked with perfect freedom. There are also double-acting hand-pumps, each two coupled; feed donkey engines, each with double-acting pumps 4 inches in diameter; bilge donkeys, each with double-acting pumps 6 inches in diameter, and fireengines, with double-acting pumps 8 inches in diameter. It may be mentioned that the engines which work the circulating-pumps are also made to pump out the bilge, in the event of the ship springing a leak or sustaining damage from being rammed; that the centrifugal pumps are to be sufficiently powerful to perform the same work in case of emergency; and that a Kingston valve is fitted through the bottom. in connection with each fire-pump. Each cylinder is fitted with an expansion-valve, having a variable cut-off, with an extreme range of from one-sixth to one-half stroke. These valves are cylindrical gridiron-valves, of phosphor-bronze,* 3 feet in diameter, working on cast-iron gridiron seats, and giving a minimum of clearance between the expansion-valve and main slide. They are worked by an eccentric on the crank-shaft and a slotted lever, and are all connected to a shaft in front of the engines, so that they may be This alloy is now gaining favor for cylinder valve-faces where high-pressure steam is used, and for bearings where heavy pressures are applied. Its component parts consist of copper, tin, and phosphorus, and it is capable of being made tough and malleable, or hard, according to the proportions of the several ingredients. It is rendered so liquid in the molten state by the addition of the phosphorus that it forms very clean castings. Messrs. Levi & Kingel, of the Val Benoit nickel works, near Liege, Belgium, have, for a number of years past, been engaged in making experiments for the purpose of improving bronzes of this kind. The results of their experiments are thus summed up by M. Dumas: "The color, when the proportion of phosphorus exceeds per cent., becomes warm and like that of gold largely mixed with copper. The grain and fracture approximate o those of steel, the elasticity is considerably increased, the absolute resistance under thrown out by a single handle. Each engine is also fitted with a common injection apparatus. The crank-shaft is formed of three pieces, the diameter of the bearings being 173 inches. The propellers will be about. 20 feet in diameter, and will be worked outwards, the thrust being at the after end. The shaft tubes are of wrought iron, supported by struts, while the shafting will be made of Whitworth fluid compressed steel, with solid couplings. It will be hollow, the inner diameter being 10 inches and the outer 16 inches. The faces of the high-pressure cylinders are formed of phosphor-bronze 2 inches thick; the liners of the cylinders are also constructed of the Whitworth compressed steel, which possesses properties rendering it not only extremely light, but at the same time much more trustworthy than the ordinary metal used for this and shafting purposes. Each engine will be fitted with a governor, to prevent racing in stormy weather; and in addition to the hand-gear, small auxiliary engines will be erected for turning the main engines. BOILERS. The steam is to be furnished by twelve boilers, eight single-ended and four double-ended. They are constructed of the best Lowmoor plates, tested to 21 tons lengthwise and 18 tons crosswise, and the pressure of steam will be 60 pounds per square inch. The four double-ended boilers are 17 feet long, 9 feet 3 inches wide, and 14 feet 3 inches high, with four furnaces in each. Four of the single-ended boilers are 9 feet long, 13 feet 7 inches wide, and 15 feet 6 inches high, with three furnaces each, and the four remaining single-ended boilers are 9 feet long, 11 feet wide, and 13 feet 4 inches high, with two furnaces, each having a separate fire-box. All the boilers are to be clothed with four thicknesses of boiler-felt, and covered with galvanized sheet-iron, and are stayed to prevent their moving by concussion when the ship is engaged in ramming. They are to be supplied with water by four feed-pumps, which are attached to each engine, the pumps being 7 inches in diameter, and having a stroke of 2 feet 8 inches. In the event of the feed-pumps receiving injury, the boilers are provided with four small auxiliary engines, (one in each boiler-room,) and having separate connections with the boilers. The two auxiliary engines which are used for washing the decks are also arranged to work the fire-engines in the engineroom. The safety-valves are fitted with springs upon an improved plan. The smoke-pipes, of which there will be two, are 65 feet high from the dead-plate of the lower furnaces. The bunkers, which are placed at the water-line along the unarmored sides of the ship, where the entrance of shot or water cannot injure them, are built to store 1,200 tons of coal, and are so disposed that their contents can be approached from the upper and lower compartments independently of each other. a fixed strain becomes more than doubled, the density is equally increased, and to such 1 RIG. The Inflexible is also to possess sail-power, with respect to the advantages of which, however, considerable diversity of opinion exists. She will be brig-rigged, having two iron masts, but no bowsprit or stay gear. The fore-mast will be 36 inches in diameter, and will measure 83 feet 6 inches from the deck to the head, while the main-mast will have a diameter of 37 inches, and a height of 96 feet. Each will have a topmast and top-gallant mast, with lower yard, top-sail yard, and top-gallant yard. The total area of sails will be 18,470 square feet. In time of war it is intended that the ship will carry no masts, except for signal purposes. The anchors, of which there are to be four, will be of Martin's selfcanting pattern. WEIGHTS. The estimated weight of the hull is 7,300 tons. The engines will weigh 614 tons. The propellers, shafts, and stern-fittings weigh 151 tons each; the boilers, smoke-pipes, casings, &c., 522 tons, and the water in the boilers when ready for steaming is estimated at 190 tons. The date named in the navy estimates for the completion of this ship is March, 1878. As a new type of a man-of-war, the leading features of the Inflexible may be summed up as follows: The armor is confined to the central fighting portion and to the main substructure which floats the ship. An armored deck 7 feet under water divides the vessel into two sep arate portions. The unarmored ends are so constructed that the vessel will float even when they are penetrated by shot. The ship has a wide beam and a comparatively light draught of water. The deck-houses give a high bow and stern, and the turrets are so arranged as to enable all four guns to be fired both ahead and astern, or on either beam. The Inflexible has been accepted as the type of the British future line-of-battle ships, and the Admiralty have determined on building others, two of which are already under process of construction, viz, the Agamemnon at Chatham, and the Ajax at Pembroke. These sister vessels are to be of reduced dimensions. They will be 280 feet long, 66 feet wide, and will have a displacement of 8,500 tons, with a mean draught of water of 25 feet. They are to carry armor 18 inches thick, and an armament of two 38-ton guns in each of the two turrets. The indicated horse-power is to be 6,000. In perusing the foregoing description of the Inflexible it has been seen that her double bottom is divided and subdivided into an unusual number of spaces, and that the water-tight bulkheads have been introduced to an extent not before attempted, and in fact almost every conceivable precaution has been taken to make her secure against the ram and the torpedo. If, however, she should be fairly struck by several powerful fish torpedoes it is quite probable she would be crippled, waterlogged, or possibly sunk. The question therefore presented is, whether two vessels of smaller dimensions, each carrying two 81-ton guns instead of four, would not have been a safer and in some respects a better investment. |