418 REPORT— 1860. 



On the Material and Proper Form of ProjettUes for the Penetration of Iron 



Defences. 



"We have abeady seen that it is almost useless to fire cast-iron projec- 

 tiles against iron defences if penetration is required ; it will therefore be 

 neccssaiy to use a material which will effect our purjjose at a moderate cost. 



Steel is a most expensive material for shot ; and as we have proved that 

 Palliser's chilled iron is almost, if not entirely, as good as steel, all our 

 projectiles for battering-purposes wUl most probably be made of this material. 

 The proper form of front or head to be given to hardened projectiles for use 

 against iron plates is a subject of much importance. Various forms have 

 been proposed for this purpose. 



Mr. Whitworth relies on the flat-headed form, while most of Sir "Wm. 

 Armstrong's projectiles have been round-headed or hemispherical; Major 

 Palliser has used elliptical heads, and lately, in the projectiles for the 13- 

 inch gun, a sharp-pointed form. The flat-headed form is supposed to be 

 right, because it is generally used as the form of a punch. But although 

 a flat-headed punch, when used with a die, will make a nice dean hole in a 

 plate of iron, it by no means foUows that a sharp-pointed or " centre " punch 

 will not make a rugged hole of equal size, with the same, if not greater ease. 



The manufacturer uses the flat-headed punch in order that he may be 

 enabled to cut out a dean hole ; but the artilleryman docs not care what 

 shaped hole he makes so as it is made ; and if he has a preference at all, 

 it is for a ragged hole which it is difficult to mend or plug iip. 



We find in practice that the pointed form is the best for the artillery- 

 man, particularly when the iron plates are backed by wood. 



A consideration of the result of firing at a backed target will make this 

 evident. 



The flat-headed or round-headed shot punches out a jnece of the armour 

 plate, and diivcs it into the backing ; the shot, ho-\^^ever, has no means of 

 ridding itself of this piece of armour plate, and consequently it has to push 

 ■it in front of it through the hacTcing. Thus in targets penetrated by flat- 

 headed or round-headed shot, we invariably find that the piece of annour 

 plate has passed through the target along with the shot. It is needless to 

 remark that this piece of jagged armour plate must greatly increase the 

 resistance which the shot meets in passing through the backing. 



When, however, the shot is of the form of a pointed ogival, the results 

 of its action are far diff'erent : this projectile cuts through the armour 

 plate, or rather tears it through, and the plate is bent back and forced into 

 the backing round the edge of the hole. The shot thus passes through the 

 backing -without carrj-ing any jagged armour in front of it*. 



A very good illustration of this was obtained in the practice with the 

 13-inch ML gun at the 'Hercules' target; and the photographs of the 

 target taken when the plates were removed show the effect in the most marked 

 manner. 



Round 1141 : a steel round-headed shot penetrated the lower or 8-inch 

 plate of the ' Hercules,' forcing the piece of plate against the backing. On 

 the plate being removed, this piece of iron was foimd exactly as the shot 

 had punched it out, and endeavoured to force it forward. The total pene- 

 tration or indent was about 13 inches. 



Round 1145 : a chQled iron pointed-headed shot also struck the 8-inch 



* In practice with ogival-headed shot we seldom, if ever, find that any part of the 

 armour plate has passed through the target witli the i^rojoctile. 



I 



