PENETRATION OF IRON PLATES BY STEEL SHOT. 419 



plate and tore thi-ough it, bending the edges of the plate back, and forcing 

 them laterally into the backing. The penetration in this case was 22 inches ; 

 and if the shot had been a perfect casting it would probably have had a 

 greater effect. 



We see also from Table XII., in the Appendix, how much greater penetration 

 was obtained by a steel sheU wnth a soUd head in the form of a pointed 

 ogival, than where this form was not used. 



There is another disadvantage which the blunt-headed form labours under, 

 viz. the tendency to " set up " or bulge at the head ; and this result is 

 often ver}^ marked. A pointed head, on the contrary, does not " set up " 

 to anything like the same extent, and almost all those which have been 

 fired have preserved their points intact after passing through the plates. 



On the whole, it may be said that in the case where the projectile ought 

 to be capable of piercing the plate or target there is little difference between 

 the effects of a flat head and a hemispherical head ; but when the target is 

 beyond the power of the shot the hemispherical head makes the deepest indent. 

 This is clearly shown in the case of the experiments with a waU-piece at a 

 4-5-inch unbacked plate, and 12-pouuder Armstrong and Whitworth gims, at 

 the Scott- Russell target. In every case where the target could not be pene- 

 trated, the round gave a deeper indent than the flat head. 



The Tables in the Appendix give the results of some late experiments, 

 which clearly show the great superiority of the pointed head. 



In these experiments, both steel and Palliser's chilled shot were used. 

 All the projectiles were fired from the same gun, under the same circum- 

 stances, the velocity of each rovind being observed. The targets consisted 

 of a strong structure, representing the side of an iron-clad vessel protected 

 by solid plates of 6 inches thickness, backed by 18 inches of compact teak, 

 an iron skin of two half-inch plates, the usual iron ribs, tfcc. A second 

 target of unbacked 4-5 -inch plates, inclined at an angle of 38° with the 

 ground, was erected at the same distance. 



The projectiles were of a mean weight of 115 lbs., and of the following 

 forms of head, viz. : — 



For Palliser's Chilled Shot. 



1. Ogival, head struck with a radius of 1 diameter, and broiight to a point. 



2. Belgian form, head struck with a radius of 1-47 diameter, and pointed 

 in the shape of a cone. 



3. EUiptical, the height of the eUipse being equal to the diameter of the 

 projectile. 



For Steel Shot. 



1. Hemispherical. 



2. Ogival, head struck with a radius of 1 diameter, and brought to a 

 point. See Table XI., in the Appendix, round 1186 to 1201. 



From this it appears — 



1st. That hemispherical-headed steel shot, strildng the box target with 

 a " work " of 6S tons per inch of shot's circumference faUed to penetrate 

 completely: this result might be expected, as from calculation it would 

 require about 82 tons per inch of circumference to send a hemispherical- 

 headed shot completely thi-ough such a structure. 



2nd. That ogival-headed steel shot, the head being brought to a point, 

 striking the above target with a " work " of 68 tons per inch of shot's 

 circumference, penetrated completely, with some remaining force left. 



3rd. That pointed chilled shot, striking the above target with a "work " of 



2e2 



