It does not have a touch-screen, nor can it play audio / video files or give audible instructions, but this is the world's first sat nav - invented in the 1920s. The Plus Fours Routefinder was designed to be worn on the wrist - relying on good old-fashioned paper maps wound around wooden rollers, which the driver turned en route. The tiny scrolls also showed the mileage and gave a "stop" instruction at the journey's end. It was intended to get the drivers around UK, but with the automobile revolution just picking up steam there were very few cars on the road and the gadget never took off.

Via - Annanova