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KF5JRV > TECH 02.03.17 19:21l 28 Lines 1428 Bytes #999 (0) @ WW
BID : 11525_KF5JRV
Read: GUEST
Subj: Houfeng Didong Yi
Path: IW8PGT<IZ3LSV<IW2OHX<UA6ADV<CX2SA<N0KFQ<KF5JRV
Sent: 170302/1715Z @:KF5JRV.#NWAR.AR.USA.NA #:11525 BPQK6.0.13
In 132 AD, Chinese astronomer Zhang Heng created the Houfeng Didong Yi, a
device that detects the ground’s movement during an earthquake. It couldn’t
predict quakes but it did show what direction they were coming from — even when
they were hundreds of miles away!
Zhang was also a mathematician and mechanical engineer who constructed many
practical devices, including a cart for measuring the Chinese mile, and an
early armillary sphere, or globe-shaped model of the heavens. His seismometer,
the first known instrument built to detect earthquakes, was important, because
devastating quakes happened in many remote regions of China. So a detection
device helped the emperor know when and where to send timely aid from the
capital.
The bronze device featured eight metal dragons attached to what looked like a
big coffee urn. Each dragon’s head pointed in a different direction (north,
south, east, west, northeast, southeast, southwest, and northwest), and each
had a copper ball in its mouth. Below the dragons’ mouths were eight copper
toads with their mouths upraised.
Scientists think the mechanism inside the device was a type of pendulum system
that was very sensitive to vibrations. When an earthquake happened, an observer
could tell which direction it came from because the mouth of the dragon facing
that way would open and drop the ball into the mouth of the toad below.
73 Scott KF5JRV
KF5JRV.#NWAR.AR.USA.NA
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