World’s Earliest SatNav

"Satellite navigation (SatNav) is a lot older than previously thought. In fact, it’s even decades older than man-made satellites themselves. This fantastic contraption, called the ‘Routefinder’, showed 1920s drivers in the UK the roads they were travelling down, gave them the mileage covered and told them to stop when they came at journey’s end."

http://strangemaps.wordpress.com/2008/09/28/314-watch-the-road-worlds-earliest-satnav/