Friday Seismometer Blogging: Houfeng Didong Yi
This is a replica of the world’s first seismometer, which was built in China, AD 130-ish. I haven’t been able to find a good diagram of the internal mechanism, but there’s some kind of pendulum in there, which jiggles in response to earthquakes. This moves a little lever on the dragon’s head, so that the ball drops from its mouth into that of a waiting toad.
Then it goes “ping”.