IT is a cruel and poignant certainty that the children who died in the wreckage of their school during the earthquake this week in Dujiangyan, China, knew all too well that their country once led the world in the knowledge of the planet’s seismicity. k
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They would have been taught, and proudly, that almost 2,000 years ago an astronomer named Chang Heng invented the world’s first seismoscope. It was a bizarrely imagined creation, with its centerpiece a large bronze vessel surrounded by eight dragons, each holding a sphere in its mouth. k0v&U@+-J
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A complex system of internal levers ensured that if an earthquake ever disturbed the vessel, a ball would drop from a dragon’s care into the mouth of a bronze frog positioned underneath. By observing which dragon had dropped its ball, Chang Heng could ascertain the location of the quake. And always, as the emperor for whom Chang Heng fashioned the device noted, the earthquakes came from the mountains in the west, where Dujiangyan lies. =j~vL`d2]
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