180: REPORT—1862. 
No. of | Crushing | Ultimate Pressure Pressure 
Experi- | weight in | compression |per squareinch|persquareinch Remarks. 
ments. lbs. in inches. in lbs. in tons. 
1 73,428 122,115 54°51 
2 68,062 125,787 Both ends flat. 
WMEATOMIE ecw | | webene 123,951 Areas 5674 and *7088. 
3 35,540 62,636 
4 40,916 57,725 One end rounded. 
ECR 1) sscece |) eimauwrece 60,180 Areas *7088 and ‘7088. 
Lt 5. 38,260 53,978 
6. 37.580 53,030 Both ends rounded. 
Mean 37,920 Areas *7088 and °7088. 
From the above experiments, it is evident that the round-ended shot loses 
more than one-half its power of resistance to pressure in the direction of its 
length ; and this may be accounted for by the hemispherical end concentrating 
the force on a single point, which, acting through the axis of the cylinder, 
splits off the sides by a given law of cleavage in every direction. On the other 
hand, the flat-ended specimens have the support of the whole base in a vertical 
direction ; and from these we derive the following comparative results :— 
Taking the resistance of the flat-ended shot at 54°82 tons per square inch, 
and that with hemispherical ends at 26:86, we have a reduction from the 
mean of the flat-ended columns of 27:96 tons, being in the ratio of 100: 49; 
or, in other words, a flat-ended shot will require more than double the force to 
crush it than one with one of its ends rounded. Now, as the same results 
were obtained at Shoeburyness, in the appearance of the fractured ends, when 
similar shot was fired from a gun, we arrive at the conclusion that the same 
law is in operation whether rupture is produced by impact or statical pressure. 
In the experiments on cast-iron shot, the mean compression per unit of 
length of the flat-ended specimen was ‘0665, and of the round-ended +1305. 
The ratio of the compression of the round- to the flat-ended was therefore 
as 1:96: 1, or nearly in the inverse ratio of the statical crushing pressure. It 
has been correctly stated that it requires a considerable amount of force to 
break up shot when delivered with great velocity against an unyielding 
object, such as the side of an iron-cased ship, or a target representing a por- 
tion of that structure; and it may be thence inferred that the force expended 
in thus breaking up the shot must be deducted from that employed in doing 
work on the plate. This is confirmed by experiment, which shows that though 
the whole of the force contained in the ball, when discharged from a gun at a 
given velocity, must be delivered upon the target, the amount of work done, 
or damage done to the plate, will depend on the weight and the tenacity of 
the material of which the shot is composed. 
Tf, for example, we take two balls of the same weight, one of cast iron and 
the other of wrought iron, and deliver each of them with the same velocity 
upon the target, it is obvious that both balls carry with them the same pro- 
jectile force as if they were composed of identically the same material. The 
dynamic effect or work done is, however, widely different in the two cases, 
the one being brittle and the other tough: the result will be, that the cast 
iron is broken to pieces by the blow, whilst the other either penetrates the plate 
or, what is more probable, flattens its surface into a greatly increased area, and 
