Model of a Lifting Screw; Model of a screw sleeve between the stern and the stern; with a part of the keel and the rear apostles. The screw light device consists of a loose frame with a screw that can be hoisted up and down in the sleeve on a rope that runs over a disc at the top of the screw sleeve and a disc in the screw frame. The screw is a Mangin screw; a four-blade propeller; composed of two two-blade screws that can be set in parallel for lifting. The propeller is released by pulling the shaft into the ship. The vertical rails against the stern and the stern over which the screw frame moves are provided with teeth; this includes catches of the screw window that prevent slipping back. The catches can be held back so that the screw window can be lowered. Bars against the stevens keep the screw window down and must be removed before lifting. Scale 1:10 (estimate).; Nederlandsche Stoomboot Maatschappij Fijenoord; Rotterdam; c. 1857; wood (plant material); brass (alloy); rope; h 114 cm x w 45 cm x d 28 cm