PEOPLE

Zhang Heng pictured with a scale model of his “earthquake weathercock”

movements of the ground more sensitively Use a toad to than a human could. To add to the uncertainty, we can never know if the seismoscope’s famous quake detection happened as chronicled in the Hou catch a quake Han Shu, which was completed around 440, centuries after Zhang’s death. Suspiciously, the detection goes unmentioned in an earlier history, the Hou Han Ji, source of the Hou Han The world’s first seismoscope was created in AD 132 by Shu’s description of the device. Moreover, polymath Zhang Heng, but did his legendary device really work? the later document lists seven earthquakes between 132, when the seismoscope was made, The evidence is shaky, finds Andrew Robinson and 139. And although one of these quakes, in 138, caused destruction in Longxi, the record clearly states that the tremors were also felt in the capital. Cullen suspects the detection story is “fan fiction”, inspired by admiration for CLANG! An ornate dragon’s head suddenly mountains. The chief reason for detecting audience were prime candidates, but glared at spat a metal ball into the mouth of a bronze earthquakes, thought Zhang, was because they Zhang so menacingly that he thought better of “Was the quake-detection toad crouching patiently beneath it, and were heavenly omens indicating misconduct nominating them. Nevertheless, they later story ‘fan fiction’ inspired by officials at the court of the Han emperor were of government officials. “The heavens crack, slandered him to the emperor, so it was not astonished. And sceptical too: this supposedly and the earth shakes,” is one of many Chinese surprising that his career encountered his mechanical creativity?” revealed that an earthquake was happening sayings about high politics and everyday life. periodic setbacks. He reflected upon his elsewhere in China, yet they felt no tremors in After a particular earthquake shook the travails in some of his many poems, which Zhang’s undoubted mechanical creativity. the capital Luoyang. Sure enough, just a few capital, Zhang submitted a statement to won him literary fame, such as these closing These doubts haven’t stopped many experts days later, galloping horsemen brought news Emperor Shun describing the disaster as a lines from his final composition, written in China, Japan and elsewhere attempting to of a destructive earthquake in Longxi, divine comment on the failure of a new policy during his retirement: “If I set my mind free reconstruct the seismoscope. In China, 700 kilometres away. “Upon this everyone for recruiting the talented and virtuous for beyond the common world / Why care for museum curator Wang Zhenduo modelled it admitted the mysterious power of the office. If movements within the earth were worldly glory or disgrace?” twice: in 1936 with a conventional pendulum instrument,” or so the story goes. From then portents of corruption within the court, an and in the 1950s with an inverted pendulum. on, officials in the Bureau of Astronomy and instrument to detect earthquakes might Neither responded to real earthquakes, Calendar were required to note the occurrence greatly assist the emperor. The imperial Heavenly inspiration ock including the devastating Tangshan quake of rst e and direction of earthquakes in the imperial eunuchs – advisers with the ear of the Zhang spent the first few decades of his life tt 1976, which killed hundreds of thousands of u realm indicated by this, the world’s first emperor – probably felt differently. On one far from the centre of imperial power. He h people. This quake caused tremors in Beijing, X/S E /R

seismoscope. occasion, the young emperor was said to have was born in AD 78 to a distinguished but not t where the second of Wang’s models was kept. China has kept records of earthquakes summoned Zhang to his chambers and asked wealthy family and it wasn’t until 112 that he During the past decade or so, a Chinese -Violle since at least 780 BC – longer than any other him to name the most despised men in the was summoned to the capital by Emperor An r Academy of Sciences team led by retired

country – and has suffered the two deadliest kingdom. The eunuchs present during the to become a junior official, as a result of his Roge geophysicist Feng Rui has built and tested a quakes in history. So perhaps it’s unsurprising broad learning. Zhang then worked his way up handsome new model with a conventional that a Chinese official, Zhang Heng, should One of many variations on the seismoscope, in the ranks, including taking a stint as imperial according to some apocryphal teachings akin the Hou Han Shu speaks volumes on the pendulum that is now prominently displayed have been the first to create a seismoscope, London’s Natural History Museum collection astronomer/astrologer. Inspired by the to the prophecies of Nostradamus. In 136, device’s outer appearance, it contains only a in Beijing’s Science and Technology Museum. around AD 132. His striking story is told in the heavens, he wrote the first clear Chinese perhaps as a result of increasing political minimal description of the innards: “A central But it has yet to detect an earthquake, chronicles of the Hou Han Shu (the history of description of the celestial sphere including pressure, Zhang left the capital and became column capable of lateral displacement along including the great Sichuan quake of 2008. the Later Han dynasty). the equator and sun’s apparent path during the chief administrator of a princely kingdom, tracks in the eight directions [so arranged as to Another model, in London’s Natural History And what a device it was. Shaped like an urn the year. He is also said to have designed the and in 138 retired to a peaceful life of operate] a closing and opening mechanism” Museum collection (pictured, left), made for a some 2 metres across, its curved bronze case world’s first water-powered armillary sphere – scholarship in his home town. But not for in the dragons’ mouths. According to historian BBC TV programme in the 1970s from Wang’s was adorned with eight dragons’ heads and the earliest in a long line of water-driven long. He was recalled to the capital, now with Christopher Cullen, an authority on ancient 1936 design, has failed to detect an earthquake, toads oriented in the directions of the compass. astronomical clocks in China. Zhang finally the rank of imperial secretary, but died shortly Chinese science, “The description of the device too – less surprisingly, given the UK’s seismic The position of the dragon that released its became a palace attendant in 134, allowing thereafter, in 139. Whether the dramatic that has come down to us is sufficiently stability. Nevertheless, the model’s popularity ball indicated the direction of an earthquake’s him to offer personal advice to the emperor. success of his houfeng didongyi was a factor detailed to have led to numerous attempts at suggests that the puzzle of Zhang’s unique epicentre. Zhang called it houfeng didongyi: Despite his many talents, Zhang’s attitude in his recall is, alas, unrecorded. reconstruction, but not clear enough to enable invention continues to fascinate not only literally, a “wind-observing earth-movement to authority prevented his becoming the Whatever the truth, the enigmatic any of the attempts to be taken as definitive.” China, but also the rest of the world. instrument”; less literally, an “earthquake official court historian. He opposed the idea – seismoscope is his enduring legacy. It remains Surely, the central column was a sensitive weathercock”. He believed earthquakes were favoured by the emperor and certain officials – a mystery partly because it vanished without pendulum. Yet, seismologists have no clue Andrew Robinson is the author of Earth-Shattering linked to air movement, especially storm of revising the Chinese calendar and trace and partly because seismologists still how the complete mechanism could have kept Events: Earthquakes, nations and civilization winds encountering obstacles, such as compiling the history of the Han dynasty cannot agree on its inner mechanism. While mechanical friction low enough to detect tiny (Thames & Hudson)

42 | NewScientist | 3 December 2016 3 December 2016 | NewScientist | 43