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Person

Zhang Heng

A man with a long black beard and hair tied back in a bun wears traditional Han-dynasty attire, including a dark robe over a light-colored inner garment, against a neutral background.

Han-dynasty polymath (78-139 CE) who served as chief astronomer at the imperial court in Luoyang. He catalogued 2,500 stars, built a water-powered armillary sphere, calculated pi to within a hundredth, wrote influential rhapsodies in verse, and in 132 CE unveiled the world's first known seismoscope. He is the figure most often invoked when historians of science argue that early Chinese instrumentation has been chronically underrated.

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