NABUNKEN NEWS vol.45

Treasured Article of the Asuka Historical Museum --- A model of rokoku presiding over everlasting history

　Currently, a model of “Rokoku" is being exhibited in the lobby of the Asuka Historical Museum. The Rokoku means a water clock using a siphon effect. The model exhibited at the Museum was made consulting the original of the Qing dynasty owned by the Palace Museum in Beijing, China. There was probably a four-step type rokoku similar to this at the Mizuochi site, Asuka capital, telling the hour to the Asuka and Fujiwara people.

　However, the rokoku model exhibited in the lobby of the Museum is not simply a replica reproducing only the form and shape. If you carefully observe the “Ya” (a graduated bar held by the Rokoku doll), then you will see that this Ya is raised extremely slowly by pooling water in the lowest water bath. This mechanism aims to visually show the partial function of the Rokoku by circulating water inside the Rokoku model at a speed 48 times faster than actual flow speed. In the Asuka period, people saw the time with this Ya. Although the Ya’s motion along the graduations of the bar is extremely small, its significance in presiding over the time management of the capital was very large.

　It is almost assuredly likely that the ancient Rokoku doctors belonging to the Ying-yang Bureau in the Asuka period were also closely observing the Ya moving by slow degrees to measure the hours, just as you are now. It would be fun to feel like an ancient technocrat, while watching the Rokoku announcing the hours of the Asuka period.

(NARITA Satoshi, Asuka Historical Museum)