Model of a Gun Port of a Floating Battery

Model of a section of the ship's side with a gun port, on a baseboard. On the outside, two heavy plates are placed in a row on wheels, over which they can slide back and forth. On the rear side, the plates are fitted with a toothed rail: for both plates there is a gear wheel, operated from the inside with a crank, to move the plates back and forth. Scale 1:10 (derived).