Although we still cannot accurately predict earthquakes, we have come a long way in detecting, recording, and
measuring seismic shock. Many don't realise that this process began nearly 2000 years ago, with the invention of
this seismoscocope in 132 AD by a Chinese inventor called Zhang ('(Chang') Heng. The device was remarkably accurate in detecting earthquakes from afar, and did not rely on shaking or movement in the location where the device was
situated.
The ancient Chinese did not understand that earthquakes were caused by the shifting of tectonic plates in the
Earth's crust; instead the people explained them as disturbances with cosmic yin and yan, along with the heavens
displeasure with acts committed (or the common people's grievances ignored) by the current events were important
signs from heaven, it was occurring anywhere in their kingdom.
Zhang Cheng was an astrologer, mathematician, engineer, geographer and inventor during the Han Dynasty (25 - 220
AD), He is credited with developing the world's first earthquake detector. Zhang's seismoscocope was a giant bronze
vessel, resembling a savovar almost 6 feet in diameter. eight dragons snaked face - down of the barrel, marking
the primary compass directions. In each dragon's mouth was a small bronze ball. Beneath the dragons sat eight
bronze toads, with their broad mouths gaping to receive the balls.
The exact mechanism that caused a ball to drop in the event of an earthquake is still unknown. One theory is that
a thin stick was set loosely down the centre of the barrel. An earthquake would cause the stick to topple over in
the direction of the seismic shock, triggering one of the dragons to open its mouth and release the bronze ball.
The sound of the ball striking one of eight toads would alert observers to the earthquake and would give a rough
indication of the earthquake's direction of origin .
23rd Feb, 2014-By April Holloway-Ancient origins.net