NEW GARRISON CARRIAGES. 
337 
consists of a strong screw under each trunnion-block, resting in a 
bearing in the bracket of the carriage and passing through a nut 
by which it is moved, the latter having a large bevel wheel formed on it, 
into which a pinion, upon the front of a shaft lying longitudinally inside 
the bracket, gears. The longitudinal shafts are driven through a suit¬ 
able train of wheels by one of two cross shafts, with winch handles, at 
the rear of the carriage. The front cross shaft is used when the screw 
lift is required to raise the gun; the rear—which drives at greater 
speed than the front—when the screws are merely following up the 
hydraulic lift.* 
The height of the axis of the gun in the lowest position is 4 ft. ins., 
when from 2° to 9° of elevation can be obtained; in the highest posi¬ 
tion 5 ft. 5i ins., when from 4° of depression to 2° of elevation can be 
given. A marker is attached to the left trunnion-block, to show what 
elevation or depression can be given at any particular height. 
Elevating gear, of the worm-wheel pattern, is fitted on both sides of 
the carriage, the elevating bar being straight and attached to the gun 
by a link, to accomodate any alterations of level of the trunnions. 
The carriage has the usual rollers and minor fittings. 
II .—-The Platform. 
(Weight, 102 cwt.; tonnage, 5*510 tons.) 
The platform is the same, in general construction, as the first pattern 
10-in. casemate platform, but higher—taking 13-in. trucks in front and 
rear—and is fitted with the same traversing and running-back gear. 
The hydraulic lift of the carriage being central, necessitates the use 
of two hydraulic buffers on the platform—one at each side. They are 
of the service pattern, with 1‘08-in. holes in the piston. 
gun when fired ; these are of two different heights, giving with the bottom of the trunnion slots 
three different levels. Over this plan, screws may be said to possess two advantages—namely, 
“ instead of three particular, levels, any desired level may be obtained with them,” and “ the level 
can be arranged at extreme traverse of the platform,” (the screws being worked at the rear of the 
carriage, while a man must pass to the side to place the block.) This second advantage seems but 
of small consequence ; for if necessary to alter the level, it is easy to traverse the platform a little 
to give the required room. The first advantage, if of any moment (and it is evidently not so 
considered for sea service), becomes very doubtful when the complication and cost at which it is 
obtained are considered. The screw lift, no doubt, is alternative, in case of failure of the hydraulic ; 
but if not necessary for other reasons, common lifting jacks might possibly furnish a simpler. 
In M.P. carriages for 38-ton guns, about to be made, it is proposed to use screws merely for 
following up and for firing upon, giving them a quick speed but not sufficient power for lifting ; 
also, instead of one central hydraulic lift, to use two movable jacks, standing each on a base 
attached to the carriage bracket outside, and acting against a stud on the end of the trunnion of 
the gun. The advantage of using two independent instead of one single jack is, however, ques¬ 
tionable, on account of the difficulty of working them uniformly ; and the use of two jacks has for 
some time been abandoned in naval M.P. carriages. 
The hydraulic lift is much more rapid, as well as easier to work than the screws. For example, 
four men on the pump lever can, without relief, raise the gun from the lowest to the highest 
position in 1 min. 40 secs .; while eight men, with relief, cannot do the same with the screws under 
12 minutes. Again, in lowering from the highest to the lowest position with the hydraulic lift, 
one man pushes the lever handle and the gun sinks in 5 secs.; while with the screws, if the weight 
of the gun rest upon them, it takes about the same time as lifting—viz., 12 minutes—and if the 
weight be not on them, between 1 and 2 minutes. 
