著者

佐々木 勝浩

出版者

国立科学博物館

雑誌

Bulletin of the National Science Museum. Series E, Physical sciences & engineering (ISSN:03878511)

巻号頁・発行日

vol.26, pp.21-31, 2003-12

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Rokoku is the water clock used in ancient China, and the origin goes back to thousands years ago. The multistage type Rokoku which has several vessels as the typical form can be mentioned, and the first vessels is for water supply, the middle vessels are for control of flow rate of water, and the last vessel is for time measurement. The last vessel has a float with the time scale which we can read and know time. Although researches of J. Needham or D. Price were known, the sufficient interpretation about the accuracy and the usage of Rokoku as a clock was not carried out. In this research, first the physical character of a single vessel was observed, subsequently the change of the water level of each vessel was calculated numerically, and then the static and dynamic characteristics of Rokoku were examined. Consequently, in multistage type Rokoku it was able to confirm that the vessels play an important role in controle of a water flow, a fixed quantity of water is supplied periodically when actual using, for example 2 times everyday (in the morning and in the evening), and in the case of that sufficient accuracy is secured, etc.