647 
MOUNTING HYDRO-PNEUMATIC DISAPPEARING 
GUNS. 
BY 
CAPTAIN L. C. M. BLACKER, R.A. 
As large numbers of these mountings are destined for coaliug stations 
and fortresses in nearly all our possessions, it may be of interest to 
some of the readers of this periodical to detail the process of putting 
the platform and carriage together, and raising the gun and shields on 
the same. 
In the first place it will be found that, as a rule, so little room is left 
in the central pit in which the roller ring rests that it is practically 
impossible to use jacks underneath the platform, and thus all the 
lowering must be done by overhead lifts with tackles, and altogether 
the mounting when fitted together is of such an awkward shape that 
considerable care is necessary throughout each step of the opera¬ 
tion. The first thing to be done is to fit the live roller ring 
together in its place. This presents no difficulties, care being taken 
that each of the rollers bears accurately on the upper surface of 
the racer. Baulks are then laid across the pit and each of the 
segmental pieces composing the platform is moved into position. 
This may be done on rollers, but as an overhead lift will be re¬ 
quired for the buffer of the heavier natures of guns, it will be as 
well to first plant the cheeks of a heavy gyn in position between the 
pit and the front of the emplacement, and fit it with a heavy gyn 
tackle and a back guy. The feet of the gyn must be placed close up 
to the edge of the central pit so as to give room for the levers to work. 
Even then the lever numbers will have to haul on the ropes from the 
top of the parapet. Fitting the trunnions of the buffer into the side 
pieces will require some management. The platform, elevator, and 
buffer having been put together, and the piston connected, the next 
step in the operation is lowering the whole mounting on to the roller 
ring. For this purpose an overhead lift presents the great advantage 
that it will enable the platform to be swung sideways if necessary so 
as to drop easily into its place when lowering with jacks, not to men¬ 
tion the difficulty in working in the confined space ; it will be found 
very hard to move such a heavy mass even an inch or two sideways 
in order to get the upper racer between the flanges of the rollers. 
Care, of course, is taken to follow up underneath with skidding so as 
to avoid damage in the event of a fall parting during lowering down. 
The slings can be passed down through the holes into which the 
standards for the shield fit. There is no necessity for connecting the 
13, VOL. XIX. 
