简体中文 ｜ English
Overview
Key data
| Item | Detail |
|---|---|
| Period of use | 1281 – 1644 CE |
| Compilers | Guo Shoujing, Wang Xun and others |
| Tropical year | 365.2425 days |
| Use | 363 years — the longest in Chinese history |
The scale of the reform
After the Yuan unification the old calendar had long drifted. In 1276 Kublai summoned Wang Xun, Guo Shoujing and others to reform it. The Shoushi calendar was promulgated in 1281, named from the “reverent bestowal of the seasons” in the Canon of Yao.
Guo Shoujing set up 27 observing stations, from latitude 15° north to 65° north — unprecedented in scale, known as the “survey of the four seas.” The measurements laid the foundation of its precision.
Four innovations
1. The grand epoch dropped. Reckoning began from a measured near epoch, without the empty computations of thousands of years.
2. Third-order interpolation. A cubic interpolation handled the uneven motions of sun and moon, more precise than the second-order methods before.
3. The arc-and-arrow method. Spherical arcs and versines were reduced to plane trigonometric relations — a Chinese geometrical invention applied to the calendar.
4. A tropical year of 365.2425 days, only about 0.0002 of a day from the modern value.
The length of its use
The Shoushi calendar was used 363 years, to the end of the Ming — the longest run of any Chinese calendar. The Ming Datong calendar carried on its methods unchanged.
A calendar used for more than three and a half centuries speaks for its precision and stability. The Shoushi is the summit of the traditional Chinese calendar and a landmark in world calendrical history.
Full text
No electronic full text of this work is available here. This calendar has no separate transmitted text; its methods survive scattered in the calendrical treatises of the standard histories. Among the histories held here, see Yuanshi, Calendrical Treatise.
The title, date, summary and index structure compiled here are offered under CC BY 4.0 (attribution: Chujia Kuang · kuangchujia.com).
Compiled and arranged by Chujia Kuang.