The slide is a centre-pivot resting on a circular track and on four rollers. It is traversed by a crank revolving gearing which works in a circular rack around the outside of the roller-circle. The carriage is similar to the ordinary type, except that it is much higher, in order to allow a greater angle of depression to the gun. Instead of in and out tackles, a runner is used which passes over a windlass fixed on the rear slide-transom. This runner throws the rear trucks in action, and then, according to its lead, runs the gun in or out. The elevating-gear for the 16-cm. gun consists of a heavy cross-bar underneath the breech, having sleeves at the extremities which clasp heavy upright screws. By revolving these screws, the bar is carried up or down. The elevating-gear for the 14-cm. gun is the old-fashioned telescopic elevating-screw. [Illustration: Training-Gear for Centre-Pivot.] [Illustration: Elevating-Gear for Centre-Pivot Carriage.] _Directing-Bar Carriage._ The carriage proper is of the ordinary rear-chock or Marsilly type, which when run out for firing is lifted from the deck on a slide or chariot, so that it may be easily and quickly trained. The chariot consists of a broad, short front-piece, mounted on two rollers; projecting forward from it is a pivot-flap which secures by a pivot-bolt just underneath the port, the rollers being canted for traversing about the pivot. Projecting to the rear from this front-piece is a tongue made of =T= iron, which is supported at its rear end on two trucks which are canted like the forward ones for traversing. When the carriage is run in, its rear end comes flush with the end of this tongue, and the forward trucks rest on the deck. In running out, however, two small rollers on the axle, inside of the brackets, catch on and mount two inclined planes which slope back from the top rear of the chariot, thus lifting the carriage completely from the deck. A breeching is used with this carriage, its bight going around a =B= block on the front of the chariot. There is also a friction compressor at the rear of the brackets, the compressor plates taking against the sides of the =T= iron, which are filled out with wood for that purpose. The forward edge of the =B= block serves as a hurter in running out. In all other respects the carriage is similar to the ordinary broadside rear-chock carriage. It is used on upper decks of large ships for light guns. _Four-Truck Carriage and Rear-Chock Carriage._ These are of the general type of old-fashioned wooden carriages. _Gun-Boat Carriages and Boat-Carriages._ These carriages are of the old-fashioned type. The former is the slide pattern, its only peculiarity being that its forward and rear rollers can be revolved for transportation on a vertical pivot. The carriage has no rear trucks. [Illustration: Directing-Bar Carriage.] [Illustration: Boat-Carriage.]