Overview
Key data
| Item | Detail |
|---|---|
| Period | Sixteen Kingdoms · Later Qin |
| Compiler | Jiang Ji |
| Year head | Jian-yin |
Jiang Ji and the Sanji calendar
The Sanji calendar was made by Jiang Ji of the Later Qin and used in the Guanzhong region. Though it was used in only one corner and never widely, its methods have value.
Testing the sun by lunar eclipses
Jiang Ji proposed checking the sun’s position by lunar eclipses: at an eclipse sun and moon are opposite, so the moon’s place gives the sun’s. The idea was taken up by later calendrists and advanced the method of the field.
Calendrists had long lacked a direct way to observe the sun’s place among the stars. Reasoning back from a lunar eclipse was an indirect means to a direct result — an ingenious turn.
Transmission
The Sanji calendar is long lost; its methods survive in fragments in the Jin shu and the Kaiyuan Zhanjing, from which only its outlines can be recovered.
Compiled and arranged by Chujia Kuang.