The Geochron has been around since the mid-sixties and I only just learned about it this week. It’s an analog, electromechanical world clock and map. The backlit, translucent map is motorized: it scrolls from left to right to indicate the rotation of the earth. Noon is at the centre of the map. The terminators actually change to reflect the change in seasons, as does the position of the overhead sun, which moves in an analemma: these are physical objects behind the map that block the light and are geared to run on an annual cycle. Again: this thing is electromechanical.

The mind boggles, and not just at the (current) mid-four-figures price tag—which is to say that they’re still making these things. (They also have a digital version you can plug into a 4K TV [Amazon] which at $500 seems expensive for what it is. But then the Geochron itself always was. These things have never been anything other than executive- or installation-grade luxury goods.)

Anyway, Matthew Dockrey of Attoparsec managed to lay hands on a used one from the eighties and went through the process of restoring it—replacing worn parts, updating the maps and so forth—and documented it in this 21-minute video. [MetaFilter]