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Zhang Heng
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Bronze replica of Zhang Heng's ancient seismoscope featuring a central ornate vessel with dragon heads around its sides and open-mouthed toads positioned below each dragon.
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Wade-Giles romanization:
Chang Heng
Born:
78 ce
Died:
139 (aged 61)
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Zhang Heng: seismoscope
Zhang Heng: seismoscope Model of Zhang Heng's seismoscope (seismograph), which he invented about 132 ce to detect earthquakes.

Zhang Heng

Chinese mathematician, astronomer, and geographer
Also known as: Chang Heng
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History

Zhang Heng (born 78 ceā€”died 139) was a Chinese mathematician, astronomer, and geographer. His seismoscope for registering earthquakes was apparently cylindrical in shape, with eight dragonsā€™ heads arranged around its upper circumference, each with a ball in its mouth. Below were eight frogs, each directly under a dragonā€™s head. When an earthquake occurred, a ball dropped and was caught by a frogā€™s mouth, generating a sound.

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