Close up of an ancient East Han Chinese seismograph dragon head replica. Invented by Zhang Henge
In 132 CE, after several earthquakes in China, astronomer Zhang Heng invented this instrument to warn people of the next one. When the ground shook, it moved a pendulum inside the jug. The pendulum pushed a lever that opened one dragon's mouth. A ball rolled out and into the toad's mouth below, sounding an alarm. The open dragon mouth pointed in the direction of the earthquake, notifying the Emperor.
Size: 4256px × 2832px
Location: Unspecified
Photo credit: © Rick Rudnicki / Alamy / Afripics
License: Licensed
Model Released: No
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