Engineering Wonders of the World
Volume I

THE ARMOUR OF A BATTLESHIP. 401 A BARBETTE SHIELD FOR TWO 12-INCH GUNS. Note how the sides are sloped to diminish the force of a shell’s impact. to withstand the blows upon the steel outer surface. Thus, in the Majestic class of battle- ship the 9-inch armour-belt has 15-inch plate- frames worked across it, 2 feet apart, with, in addition, horizontal stiffening girders. Barbettes, although well fitted by their shape to withstand blows, are supported inside the double thickness of plating by closely-spaced vertical girders. Behind armour, where men are likely to be employed in action, the in- side of the framing is also covered with plating. When armour is struck, rivets are likely to break and their heads to fly off, so that this lining gives a necessary protection to the men inside. of the ore. After all action has ceased, the metal is tapped through a hole in the side of the furnace into a large ladle holding 40 or 50 tons, and, while it is running out, ferro-manganese in a finely divided form is thrown into the ladle, where it melts and combines with the purified iron, its function being finally to remove all oxides and leave the residue in an almost pure metallic state. From the ladle the metal is tapped into rect- angular cast-iron moulds, in which it cools to form blocks known as “ ingots.” These ingots are easily converted, and rolling, into any desired article. by reheating Backing of Armour. solid steel framing is placed (1,408) The method of fixing armour to its backing and the main framework of the ship is not generally known. With hard-faced armour, such as is universally used to-day, the surface must not be pierced for bolts, since it would be liable, if struck in action, to crack badly from hole to hole. Armour bolts are now screwed into holes driven into the back of the plate, about one bolt being allowed to every 7 square feet. In order to diminish the liability of bolts to break under the im- pact of projectiles, the shank, or end farthest The belt armour of warships is based upon a “ backing ” and “ supports.” A massive system of framing is provided behind the ar- mour, with a layer of picked teak, usually about 4 inches in thickness, to form a bed at the back of the plates. In all cases the skin or hull plating of a ship behind armour is arranged in two thicknesses. In addition to this wood, a away from the screw-thread fitting into the {Photo, S. Cribb.) A SIDE BARBETTE ON H.M.S. “ DREADNOUGHT.” 26