Quote: “The Chinese philosopher Zhang Hêng invented the earliest known seismoscope in 132 A.D. The instrument was said to resemble a wine jar of diameter six feet. On the outside of the vessel there were eight dragon-heads, facing the eight principal directions of the compass. Below each of the dragon-heads was a toad, with its mouth opened toward the dragon. The mouth of each dragon held a ball. At the occurrence of an earthquake, one of the eight dragon-mouths would release a ball into the open mouth of the toad situated below. The direction of the shaking determined which of the dragons released its ball. The instrument is reported to have detected a four-hundred-mile distant earthquake which was not felt at the location of the seismoscope.” Neat.

11.30. filed under: history. people. science.