Image of the Day: the first portable navigation system, from 1920

This odd little wristwatch from the 1920s was designed to help drivers get where they needed to go. Sound familiar? That's because, it's the far distant relative of today's GPS.

Here's how it worked. The leather strap was outfitted with a small scroll with an even smaller map. As the car moved along, the scroll would rotate and show more of the route. I'm not exactly sure how it knew when to rotate, but it may not have mattered. There were so few motorists at the time that this "navigation system" never quite made it out on the road.