Scale: Unknown. Sectional design model depicting the midship gun deck for an iron cased ship, including a gun and gun port, as proposed in 1866. The side of the ship depicted slopes at an inclined angle of approximately 40 degrees, out of which projects the proposed gunport. The ship's side, gunport, gun, gun carriage and slide are painted black. The gunport casing has a hand written label applied to it and can be removed to show the cylindrical gunport. When the gun is fully retracted, the cylinder can be turned 90 degrees, effectively closing the gunport. The roof of the casing is slated to show the gun and its operation. The gun is mounted on a sliding carriage, which in turn sits on a pivoting slide and can be turned in an arc on a brass rail secured to the wooden deck. A rammer has been mounted next to the gun. The laminated wooden deck resembles planking, and three museum labels have been applied to it. The model is inscribed "D J 2174-66 Geo: Johnson - Ballew." and "Model showing a plan for working guns on board iron cased ships and doing away with ordinary portholes by cylinders of iron turning on the centre after the gun has been fired and run in, the cylinder is turned round and closes the port, Mr G Johnson 1866." The model is mounted on a baseboard which has a decoratively carved frieze running around three sides of it.