Tunnel visions

Timothy Cowin of Shropshire wants to make underground train journeys more
entertaining (GB 2 317 985). The wall of a tunnel is divided into a series of
screens, each displaying one frame of a moving picture sequence. The displayed
images change at a rate determined by the speed of the train, so passengers see
a rapid succession of different images. If the display runs at 15 images a
second or more, the images merge into a reasonably smooth action sequence.