Scale: Unknown. Model of a muzzle-loading gun, complete with pivoting carriage, from the armoured broadside ironclad HMS Northumberland (1866). The model is mounted on a wooden base board with rounded corners painted black, and incorporates the pivoting point and a pair of brass tracks, the rear most of which is inscribed with calibrations in degrees from zero to 25 degrees. The gun is mounted on a carriage which can slide backwards and forwards on a pivoting carriage. The gun and the carriage are realistically modelled in brass and steel with many working parts.