132 CE (recorded construction year) / East Asia
Zhang Heng's seismoscope makes earthquakes an instrument problem
Historical accounts describe an instrument in Luoyang that indicated earthquake direction. Its original mechanism is lost and reconstructions remain debated.
The story
The History of the Later Han assigns construction to 132 and describes balls released from dragon heads. The aim was to register distant earthquakes, not predict future ones. No original survives, and the description does not uniquely determine its mechanism. Modern replicas are not archaeological proof of the original's operation.
Connections and context
Reliable instruments must distinguish a real signal from accidental motion. Modern seismographs developed a different technical system for doing this.
Dates and precision
132 CE (recorded construction year) Documented date
Positioned by the documented year, month or day. Missing precision is not inferred.
Representative map location
Han-period Luoyang
The recorded installation city; no original instrument or exact building location is implied.
Representative coordinates · 34.68°, 112.47°
A marker identifies one representative place, such as a manuscript collection, laboratory or observing site. It does not mean the work happened only there, or assign a shared discovery to one country.
Bibliography
- Chinese Academy of Sciences | Zhang Heng's seismoscope and reconstruction research
- 中国科学院自然科学史研究所｜《自然科学史研究》2005年第4期：张衡候风地动仪功能测试和感震原理的探讨
References are listed as plain bibliography titles. They support particular facts or context; a reference does not certify every interpretation in a story.