World History

How did the first seismograph work?
Answered by Discovery Channel
  • Discovery Channel

    Discovery Channel

  1. The world’s first seismograph – used to detect and measure earthquakes - was created by the Chinese imperial astronomer Chang Heng in the early second century. It was a vessel made out of heavy bronze, with nine dragons on the outside, facing downward. Facing upward, below each dragon, were nine frogs with open mouths. A pendulum hung inside the vessel, moved only by the movement of tremors in the earth. Then, the internal levers of the seismograph would trigger the ball to fall into the mouth of its respective frog, indicating some form of measurement. It would be 1,500 years before Western civilization came up with its invention of seismographs; the Richter scale was created in 1935, and that’s what we still use today.

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