The boat-carriage is made up of two ⅝-inch plate brackets, having narrow stiffening pieces along the front and upper edges. The brackets are riveted to a bottom plate by angle-irons on the outer sides, and are connected in front by a transom of plate riveted to angle-irons, and in rear by another transom. It has two outside holding-down clips on each side. The elevating-screw admits of 10° elevation and 2° depression. The slide consists of two sides of girder-iron, 6½ inches deep, and are joined by a connecting plate, three bottom plates, and a rear transom. These bottom plates have metal friction-plates attached beneath them. The centre as well as the front is fitted with a pivot-bolt. The transporting axle bolts beneath the slide. The hydraulic buffer lies upon the centre and rear transoms, to each of which it is secured by a band. This buffer is nothing more than the ordinary type of long cylinder and piston.[3] The cylinder is nearly filled with oil through a hole in the upper rear part. In case it is desired to empty the cylinder, there is a hole for the purpose in the lower forward end. Holes of a certain diameter are bored through the piston, and the recoil is checked in proportion to the resistance of the oil in passing through these holes. The cylinder not being quite full leaves an air-cushion to ease the strain. The piston-rod is secured to the carriage, and a slight vertical play is allowed in its fastenings to prevent the jump of the gun from bending it. [3] See cut, page 203. _Carriage for Light Upper-Deck Guns._ [Illustration: Slide for Light Upper-Deck Guns.] The carriage consists of two ½-inch plate brackets connected by a bottom plate and transom. This carriage has no rollers. It is fitted with the elevating hand-wheel, pinion, and ratchet in use with the heavier calibre.[4] The toothed ratchet bolts to the side of the breech of the gun. The toothed edge of the ratchet gears to a pinion, while the back is supported by a friction-roller attached to the bracket. The pinion being inside the bracket connects with a hand-wheel on the outside, which is held by a friction-brake. The peculiarity of the slide is that it slopes to the front at an angle of 10°. It is provided with a hydraulic recoil buffer (see Boat-Carriage), and also with plate compressors. There are two rubber buffers at the front of the slide to catch the gun in running out, and an in-tackle is fitted underneath the slide. A pivot-flap projects from the front of the slide, the pivot-bolt being close to the gun-port. [4] See cut, page 199. _Carriage and Slide for 7-inch M. L. R._ [Illustration: 7-inch Carriage.]