Projection Background. In this picture the interior of a railway carriage is being filmed; and to give the impression of the landscape passing by the ingenious "projection background" is used. This background consists of a large opaque glass screen; upon which; from behind; is thrown a moving picture actually taken from a train; perhaps many months before. This picture is then photographed again; through the window; and the illusion is complete. The projector is enclosed in a sound-proof box; on wheels and with a chimney to let out the heat. Illustration for one of a set of cigarette cards on the subject of How Films are Made; issued by B Morris in 1934.