Zhang Heng
Sciences & Discovery • Historical Archive • 🇨🇳 China • 10 views

Zhang Heng 🇨🇳

張衡 (Known as "The Polymath of the Han Dynasty")
Astronomer, Mathematician, Chief Astrologer, Inventor of Seismoscope
Born 78 CE 🇨🇳 Nanyang (Henan), China
Passed Away 139 CE Luoyang (Henan), China
Lifespan 60 years old
10 views
Notice / Correction
"The sky is like a hen's egg, and the earth is like the yolk within. Heaven is great and earth is small; inside and outside there is water."

Archival Overview

Han Dynasty polymath who invented the world's first seismoscope for detecting earthquakes, built the first water-powered celestial armillary sphere, and calculated Pi as sqrt(10).

Biographical Record

Zhang Heng (78–139 CE) served as Chief Astronomer and Minister at the imperial court of Luoyang during the Eastern Han Dynasty. A universal genius of ancient China, he synthesized poetry, painting, mechanical engineering, and cosmology.

In 132 CE, he invented the Houfeng Didong Yi ('Instrument for measuring seasonal winds and earth movements')—the world's first seismoscope. The bronze vessel used an internal pendulum to drop a ball from one of eight dragon mouths into a bronze toad below, detecting an earthquake hundreds of miles away in Gansu before riders arrived with the news. He also perfected the water-driven armillary sphere and charted 2,500 stars.

Key Life Milestones

117 CE

Invention of Hydraulic Armillary Sphere

Applied water power to an astronomical armillary sphere, creating the first mechanical planetarium rotating with the heavens.

132 CE

Invention of the First Seismoscope

Constructed the bronze dragon-and-toad seismoscope that accurately detected distant earthquakes across imperial provinces.

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Final Resting Place

Perpetual Memorial
Tomb of Zhang Heng Historical Park
Nanyang (Henan), China
GPS: 33.0086, 112.5283
View on Memory Atlas
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