Tónghú lòujiàn zhìdù 銅壺漏箭制度
System of the Bronze-Pot Clepsydra and its Indicator-Rod
About the work
The Tónghú lòujiàn zhìdù is a Sòng-period anonymous technical monograph in one juǎn describing the construction and graduation of the tónghú lòujiàn 銅壺漏箭 — the standard bronze-pot Chinese water-clock with a floating “arrow” indicator (jiàn 箭) that emerges through a graduated kèchǐ 刻尺 (“notch-rule”) as the water level rises in the receiving tank. The catalog note “Zeitmessung” identifies it as a horological treatise. It is the companion text to KR3fa006 Zhǔnzhāi xīnzhì jǐlòu túshì of 孫逢吉.
Abstract
The work is undated and anonymous in the catalog. The textual style and technical terminology place it firmly in the Sòng (Northern or Southern, with a Southern-Sòng date most plausible given the parallels with the Zhǔnzhāi of 孫逢吉). It belongs to the official-bureau tradition of horological instrument-making by which the Sòng Sītiānjiān 司天監 supplied and standardised water-clocks for capital and provincial use. The tónghú design treated here uses a multi-tank cascade (typically four tanks: rìtiān 日天 → yètiān 夜天 → píngshuǐ 平水 → shòushuǐ 受水) with a píngshuǐ compensating tank to maintain constant head and therefore constant flow into the shòushuǐ (receiving) tank where the jiàn (indicator-rod) rises.
The text describes: (a) the dimensions, materials and casting of the bronze pots; (b) the geometry of the connecting pipes (tōngshuǐ 通水) and overflow channels; (c) the graduation of the indicator-rod into 100 kè (the standard Sòng day-division — Sòngshǐ tiānwénzhì preserves the same standard); (d) the seasonal substitution of summer- and winter-graduated rods to compensate for the 漢-orthodox unequal-hour scheme; and (e) the operational procedure for refill and reset at noon by sundial observation.
The text is one of the principal sources for Needham’s reconstruction of the medieval Chinese water-clock in Science and Civilisation in China vol. III (and the Heavenly Clockwork monograph). It is also the immediate antecedent of the Yuánshǐ tiānwén zhì 元史天文志 description of the imperial astronomical bureau under Guō Shǒujìng 郭守敬 (KR3fa024 and related YuánMíng works).
Translations and research
- Joseph Needham, Wang Ling and Derek J. de Solla Price. 1986 [1960]. Heavenly Clockwork: The Great Astronomical Clocks of Medieval China. 2nd ed. with supplement by John H. Combridge. Cambridge: CUP. — the principal Western study of medieval Chinese horology; uses the present text and the Zhǔnzhāi for its reconstruction of the Sòng standard tóng-hú.
- 華同旭 Huà Tóngxù. 1991. Zhōngguó lòukè 中國漏刻. Hefei: Anhui kēxué jìshù.
- Combridge, John H. 1975. “The Celestial Balance: A Practical Reconstruction.” Horological Journal 117/8 (Feb 1975): 1–7. — practical reconstruction.
Links
- Companion: KR3fa006 Zhǔnzhāi xīnzhì jǐlòu túshì 準齋心制幾漏圖式.
- Background: Sòngshǐ 律曆志 and 天文志 sections on imperial horology.