470 
THE DEVELOPMENT OF ARMOUR. 
Capped 
shot. 
the 10-in. Projectiles made at the Putilof works on Holtzers system 
broke up when fired direct or within 10 degrees of the direct line. 
Certain so-called secret process shot, however, perforated direct and 
in one case at 25 degrees with the direct or normal line. It was easily 
surmised that these shot had caps for the following reasons :—Because 
they were concealed from view. Screens were employed to catch any¬ 
thing becoming detached. The secret was said to be a process 
applied to existing shot. The energy was found to be calculated for 
a slight addition in weight. The experiments which had obtained 
success with wrought iron caps ceased. During the firing some¬ 
thing was accidentally seen in an officer’s hand for an instant 
that looked like a cap, with other slight confirming incidents. 
Subsequently it became more certainly known that caps of hard 
steel instead of iron were employed. Supposing the shot to weigh 
90*9 lbs. at 1850 f.s. velocity, they should perforate 11*8 in. of 
iron and at 2,400 f.s. 17*4 in., which should carry them through the 
6-in. and 10-in. plates respectively if their points were not broken, 
that is if the plates behaved like ordinary steel, not exceeding 9*4 and 
11*9 in. thick. This is what took place on this occasion. 
Subsequently the subject was taken up in the United States as well as 
in England, and it may be well to deal with the whole question here as 
far as possible and with this object the inserted tables are given. 
Group I. consists of selected cases when shot without caps perforated 
plates with hardened faces in an unusually successful way. It will be 
seen that it is made up of single results, no two occurring on the same 
day or with the same plate. Group II. consists of results obtained in 
England and the United States with capped shot and Group III. of the 
secret process or Russian capped shot. It may be seen in the last 
column but one, that the uncapped shot obtained a slightly better 
result than the capped in Group II. This column gives the relation 
of the thickness of the plate perforated to the thickness of wrought 
iron which the shot would be calculated to perforate. The larger this 
decimal is, the more nearly the shot disposed of the plate as if it were 
wrought iron. 
Although at first sight, it may seem strange that the uncapped shot 
capped shot thus slightly beats the capped, it will be seen on reflection to be what 
might be expected, if as the writer believes, the action of the cap is simp¬ 
ly to prevent fracture of the point. 1 For this involves the slight ad¬ 
ditional work of crushing or otherwise disposing of the cap. In shot the 
function of the cap is to secure that the shot is not robbed of its effec¬ 
tive energy by fracture, but a very small fraction of energy is necessarily 
expended on the cap itself. Without a cap, the shot nearly always 
breaks its point and is either defeated or greatly crippled; but in the 
very rare cases when its point escapes fracture, it ought to be a shade 
better than a capped shot, so that there is nothing surprising that a 
table of such rare exceptional results should compare favourably with 
the normal results of capped shot. If this is correct it is only by 
accident that this series is not better than the series in Group III. also. 
1 It has been held that the cap spreading acts as a sort of lubricant. 
Capped 
and tin- 
