118 ANNUAL OF SCIENTIFIC DISCOVERT. 



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the backing; the shot, however, has no means of ridding itself of 

 this piece of plate, and, consequently, has to push it in front of it 

 through the backing. It is needless to remark that this piece of 

 jagged armor-plate must greatly increase the resistance which 

 the shot meets in passing througii tlie backing. When, however, 

 the shot is of the form of a pointed ogival, the results of its action 

 are far different; this projectile cuts, or rather tears, through tlie 

 armor-plato, and the pieces of Iiroken plate are bent back and 

 forced into the barking round tiie edge of the hole ; the shot then 

 passes througii witiiout carrying any jagged armor in front of it. 

 Captain Noble then proceeded to give a short detail of some late 

 experiments witli pointed shot and Alderson's solid-lieaded steel 

 slull, Avhich goes to prove that this foi-m is much superior to any 

 hitlierto tiitnl. 



The subject of iron-clad ships was then entered on, and a brief 

 summary given of the experiments against targets representing 

 actual vessels. The conclusions wiiicli might be drawn from the 

 whole of tlie experiments were ; 1st, Where it is required to perfo- 

 rate the jilatc, tlie projectile should be of a hard material, such as 

 steel or chilled iron. 2d, The form of head best suited for the 

 perforation of iron plates, Avliether direct or oblique, is the ])()inted 

 ogivtil. 3d, The best form of steel shell is that in which tlie 

 powder can act in' a forward direction, and which is furnished 

 Avith a solid steel head, in the form of a pointed ogival. 4th, 

 When chilled iron can be made of the best quality, it is almost, if 

 not quite, as etfective as steel for solid shot, and, where the pro- 

 jectile can perforate with ease, the chilled shot is more formidable 

 than steel, as it enters the ship broken up, and would act as 

 grape. 5th, To attack Avell-Iiuilt iron-clads effectually, the guns 

 should be, if possible, not under 12 tons weight and 9-inches 

 calibre, fii-ing an elongated projectile of 250 lbs., with about 40 

 lbs. of powder. 6th, When the projectiles are of a hard material, 

 such as steel, the perforation is directly projiortional to the "work" 

 in the shot, and inversely jiroportional to the diameter of the 

 projectile; and it is immaterial Avhetlier this " work" be made up 

 of velocity or weight, within the usual limits which occur in prac- 

 tice. 7th, The resistance of wrought-iron ^ilates to perforation by 

 steel projectiles varies as the square of their thickness. 8th. 

 A plate at an angle diminished the effect as regards power 

 of perforation in the pi'oportion of the sine of the angle of inci- 

 dence. 9th, The resistance of wrought-iron plates to perfora- 

 tion by steel shot is not much, if at all, increased by backing simjily 

 of wood ; it is, however, much increased by a rigid backing, either 

 of iron combined with wood, or of gi-anite, iron, bricks, etc, 

 10th, Iron-built shijis, in Avhich the backing is composed of com- 

 pact oak or teak, offer much more resistance than similarly clad 

 Avooden ships. 11th, The best form of backing seems to be that 

 in Aviiich Avood is combined with horizontal plates of iron, as in 

 the " Chalmers," " Bellerophon," and " Hercules " targets. 12th, 

 An inner iron skin is of the greatest possible advantage ; it not only 

 has the effect of rendering the back more compact, but it prevents 

 the passage of many splinters which would otherwise find their Avay 



