Discovering the Routefinder

All Backbytes readers will be heading down to the British Library's exhibition of weird inventions, and clustering round the "Plus Fours Routefinder" to gawp at the world's first sat nav. Albeit without a sat, so it's really just a nav.

Created in the 1920s, you wore the Plus Fours on your wrist. Tiny scrolls show the route as you motor along the roads of Britain, which you wind on to show the bit of the road you are on. There's even a little "Stop" instruction at the end of the route. Now the Routefinder has been resurrected, we're secretly hoping Plus Fours will make a comeback too.