Yi Xing's meridian arc survey
Medición del arco de meridiano de Yi Xing
- Date
- 724-725 · confidence high
- Place
- Yangcheng (Gaocheng), Dengfeng, Henan, China
- Credited to
- Yi Xing and Nangong Yue
- People
- 👤 Yi Xing683–727
- Field
- Cosmos & Earth
What was discovered
A network of stations from Mongolia to Vietnam that measured the gnomon's shadow and the pole's altitude to relate terrestrial distance and latitude. It refuted the traditional rule of one inch of shadow per thousand li.
It is the largest geodetic campaign of its time; the value obtained (about 132 km per degree) is inaccurate.
What it led to
- calculation of the length of a degree of meridian
- Dayan calendar of 729