DISAPPEARING CARRIAGES. In the United States disappearing carriage for seacoast guns (the Crozier-Buffington) the gun's trunnions rest in the upper ends of two levers which have an axle at their centres resting in a top carriage and pins at their lower ends supporting a counterweight in vertical guides. The motion of the gun's trun nions in recoil is a resultant of the horizontal motion of the gun-levers' centre and the vertical motion of their lower ends—therefore an ellipse. The breech is held up at the proper height by a rod pivoted at bottom in a slide raised or lowered to change elevation. In recoil, there fore, the breech moves in a circular are. The gun's muzzle moves to the rear almost hori zontally until it clears the parapet—then sharp ly downward. In the loading position, the breech (the most exposed part) is protected from fire over the parapet of less than 7° angle of fall. The motion of the top carriage is controlled by a constant resistance hydraulic brake. The recoil is also somewhat absorbed by raising the counter weight, hut this is incidental, as the counter weight's function is simply to return the gun to the firing position. Pawls catch on teeth on the counterweight crosshead holding the gun in the recoiled position for loading until released by a lever. Entirely protected from the enemy's fire, the cannoneers load the gun and traverse and elevate by means of hand cranks or electric motors. This may be directed from a distance by telephone, or by one man on the sighting plat form—the only one exposed to fire—who, in the later models of carriages, can himself perform the training by electric controllers within reach.
This carriage was invented in principle by Gen. A. R. Buffington in 1872, and developed into the present form, about 1S90, by Gen. William Crozier (both of the Ordnance Department, United States Army).
The only other disappearing carriage of any importance now in use is the English Elswick carriage, in which the gun levers have fixed pivots at their lower ends and are controlled in rotation by a rod from their centres carrying at its lower end the piston of the hydro-pnemnatic cylinder, which by oil-flow softens recoil, and by air-compression stores up energy to return the gun to the firing position.
Mommt CARRIAGES. Mortar carriages have the turntable and chassis as in the preceding, but no top carriage. As they are for high angle fire and recoil necessarily downward, springs are necessary for return to firing position. In the United States model of 1896 the mortar rests on the end of a lever pivoted at its bottom to the turntable and with spring columns and hydraulie buffel be neath. Previous to the adoption of such types as these mortar carriages had been simple iron boxes with trunnion beds. See Plates of CoAsr ARTILLERY and ARTILLERY.