Paris's Pneumatic Clocks

Back 140 years ago, this wasn't so easy to get our clocks to match each other. Sure, we had electricity, but it was new, scary, and people weren't really sure what could be done with it. It was in this historic time period that Paris figured out a centralized system to keep all its clocks synchronized without having to depend on someone to wind up each clock. And the clocks didn't even have to have their own power source!

The system required burying pipes under the city, which would carry a burst of air every 60 seconds, moving all the clocks forward one minute. That sounds like an awful lot of trouble, but they ran those pipes existing tunnels, like the subway and the sewer system. The main clock that synched all the others ran on weights, but the system was designed so the machine lifted its own weights when needed! All the clocks in Paris depended on this system, whether public or private, and it kept time within a minute, depending on how far you were from the central clock. This video has a 65-second skippable ad at 3:45. (via Nag on the Lake)