AND USEFUL ARTS. 83 



as large, though it differed somewhat in shape, according to the an- 

 gle. They could only account for this fact by supposing that the 

 damage was done by the instantaneous concussion, and not by the 

 shot boring or punching a hole through. 



The Committee also tried experiments with a target composed of 

 iron bars ; but they found that the resistance offered was not nearly 

 so great as by the iron plates. 



The velocity of this shot from the Armstrong gun was found to be 

 about eleven hundred feet per second. 



On the same occasion, in order to test the different plans of iron 

 plating, two differently formed targets were used. One of these was 

 constructed of f-inch wrought iron placed upon ribs to represent an 

 iron ship, and the shield, five inches thick, was placed directly upon 

 what would be the outer skin of the ship. The other target was made 

 of timber eighteen inches thick, to represent a wooden ship. This 

 was covered with iron plates three inches in thickness, of angular 

 form, like a wide letter V. 



In both cases, the plates were found practically shot-proof, but the 

 fastenings gave way by which the plates were secured to the target. 

 The plates were fastened to the iron target by rivets passing through 

 the skin and entering the plate, like tapped screws, to the depth of 

 an inch and a half. These screws were nearly all broken toy the 

 shots. The 3-inch plates were fastened to the target by f-inch bolts 

 eighteen inches apart. These bolts were the first things to yield in 

 this target. It was found also that when the plates were broken 

 the fracture generally commenced at a bolt-hole. 



In another instance, an experimental vessel, called the " Trusty," 

 was covered with thick iron plates, and exposed to solid shot from 

 Armstrong's and Whitworth's rifled ordnance. On the first dav four 



/ 



shots were fired at four hundred yards' distance with Armstrong 80- 

 pounders, and each broke the plating so as to expose the inner lining 

 of wood. The fifth shot did not penetrate ; the sixth was a bolt of 

 puddled steel, weighing eighty-eight pounds ; it penetrated the plate, 

 and passed in a slanting direction to an upper deck beam, where it was 

 broken into several pieces. Ten shots were fired at this distance, two 

 of which missed, but aH the others broke the outer plates, yet did little 

 damage to the interior lining. 



On the second day's firing, the distance was two hundred yards, 

 with an Armstrong 100-pound iron conical bolt for the three first 

 shots. The first started a plate half an inch at one end ; the second 

 fractured a plate the whole of its length ; the third struck a joint and 

 passed completely through the plates, opening the joint three-fourths 

 of an inch. The fourth was a bolt of homogeneous metal (fine steel) 

 weighing eighty pounds. It struck the started joint of the plates, 

 passed through it, struck an iron knee, tore it away, and drove a piece 

 of the iron plate into the water-way on the opposite side. The next 

 shot was a 100-pound bolt of homogeneous metal. It forced in a 

 piece of plate nineteen inches long and seventeen inches broad, to a 

 depth of eight and one-half inches. Nine shots were fired, one of 

 which missed. They either broke or greatly damaged the plates, but 

 the inner planking of oak, twenty-five inches thick, was little in- 

 jured. 



