ARMOUR AND ITS ATTACK BY ORDNANCE. 
98 
space it is very desirable to place a piece which plays an important 
part, and on which a besiegers'’ fire will be concentrated. In such a 
case, a gun in a disappearing shielded mounting or turret may be of 
great value. The difficulty is mainly one of space, weight, and 
expense. A powerful gun means a long piece with strong recoil, and 
this being awkward to deal with, the tendency of guns on disappearing 
turrets and mountings is to be lighter than would be expected, and 
hence no doubt it is necessary to watch against the expenditure of 
means out of proportion to the power obtained. Thus there are places 
where, as an alternative, a gun might be fairly concealed, especially 
with smokeless powder, but in a regular siege, concealment soon 
comes to an end, continued practice discovers everything, and protec¬ 
tion is then better than concealment. Here turrets and disappearing 
mountings have their field for action. A few definitions may be 
desirable to distinguish the classes of shields apart. In a turret the 
entire structure, walls and platform, as well as guns, generally revolves 
on trucks. In a shielded mounting , the shield or dome and gun revolve 
on a centre pivot. A disappearing shielded mounting only rises above the 
surrounding wall or glacis plate in coming into action, and after firing 
descends into the position of eclipse. In a shielded emplacement , the 
shield is a fixture, a mortar with a spherical body moves in a central 
hole in the shield, forming a ball joint on the top of a supporting 
pillar. 
Lastly, special attention is invited to the movable shielded mounting, 
which consists of a gun in a sheet steel cylindrical structure with an 
armoured roof, which is placed on wheels, and can be brought into a 
gun pit, where it assumes an extremely strong position. Thus, in the 
defence of a fortress fresh ground might be taken and a gun placed in 
a spot which might greatly annoy besiegers and prove a valuable 
element in defence. 
It may be noted that in all the trials smokeless powder was used, 
supplied by the United Rothweil Hamburg Company, from whom we 
in England obtained our first cocoa powder. The composition of the 
powder is a secret; it is almost wholly smokeless, and may be conjec¬ 
tured to resemble others which consist of gun-cotton in some form 
with a proportion of nitro-glycerine. 
Passing by the trials of quick-fire guns, certain specimens of shielded 
designs may be noticed as included in the subjects of the lectures. 
The 5‘7 cm (2’24-inch) 25-calibre quick-fire gun in disappearing 
shielded mounting, shown in Eig. 21, was exhibited to show its work¬ 
ing and powers. It is aimed and worked by one man, and another to 
assist and change round when required. He sits on a saddle so 
contrived as to set gear absolutely checking the recoil of the gun 
when turned down. In this position, he works the turret with his 
feet, and when the gun is run back, the hood with gun in it is raised 
or lowered very easily indeed, being well balanced by a counter-weight. 
Practice was made with ring shells against a line of 20 skirmishers 
with supports at 1300 ra (1640 yards) range. Twenty rounds were 
fired—10 with slow and 10 with quick-fire; 277 hits were made on the 
skirmishers and 22 on the supports. 
