50 ANNUAL OF SCIENTIFIC DISCOVERY. 



The target consisted of five and a half inches of the best plate iron, 

 fastened with through bolts upon a teak timber backing nine inches in 

 thickness. As an additional security, iron plates ten inches wide and 

 one and one-half inch thick were let into the teak backing, and placed 

 longitudinally at the back of the joints of the centre and top and 

 bottom armor-plates. The target was, moreover, further strengthened 

 by covering the joints of the skin plates, longitudinally, with five- 

 eighths plates eighteen to twenty inches wide, let into the back of the 

 teak, and bearing against the outside of the skin. 



Four round shot were fired from the 150-pounder Armstrong gun. 

 The first three were cast iron, weight one hundred and fifty-six 

 pounds; the last wrought iron, weight one hundred and sixty-two 

 pounds ; the charge in each case was fifty pounds of powder ; the 

 range, two hundred yards. No. 1 struck the centre-plate (which is nine 

 feet long and three feet and four inches wide) about two feet from the 

 port, midway between the top and bottom edges. It penetrated the 

 armor-plate, making a hole twelve inches in diameter, and, crushing 

 through the teak backing, burst the ship's skin-plate open, making 

 three large cracks, through which splinters of wood protruded behind, 

 split one of the frames across, broke off the points and nuts of four 

 armor-plate bolts, and four or five wood bolts. Several bolts of the 

 plate above were started by the shock. 



No. 2 hit the top plate (which, as well as the bottom plate, was 

 about eleven feet long and three feet four inches wide), made a hole 

 twelve inches in diameter through it, and forced a way through the 

 teak backing and skin-plate. Large fragments of the armor-plate, in- 

 cluding the front piece bearing the mark of the shot, were found on 

 the ground ten or twelve yards behind the target, and five or six bolt 

 ends and nuts were broken off. 



No. 3 made a hole, of the same diameter as before, clean through 

 the bottom plate. Large pieces of the shot and armor-plate passed 

 through the target ; the cone of the shot, imbedded in the portion of 

 plate carried away at the moment of impact, w r as picked up some yards 

 in the rear. In addition to the hole through the armor-plate, its upper 

 edge was split longitudinally a length of two or three feet, showing 

 the lamination of rolled iron. 



No. 4 struck the centre-plate, and, being of wrought iron, did not 

 break up like the cast-iron shot, which invariably fly into fragments, 

 but flattened and stuck fast in the armor-plate, leaving one-third of 

 its diameter outside. This effect arises from the ball squabbing out, 

 from its own force, and becoming too large to pass through the hole 

 made at the moment of impact. The diameter of the protruding 

 portion measured thirteen and a half inches, that of the shot being 

 ten inches. The effect of this missile was more destructive than that 

 of the cast-iron shot. Keeping entire, it does all its work in damaging 

 the target, whilst the latter expend part of their force in destroying 

 themselves. Large pieces of the armor-plate were driven through 

 the target, crushing the wood backing to shreds, bursting a great 

 opening through the skin-plates, and completely smashing two more 

 frames. 



The discharge of this shot brought the destructive action of the 

 150-pounder to a close, for the gun burst in firing the fourth round; 



