The , was a universal clock designed by the Japanese inventor

Hisashige Tanaka was a Japanese businessman, inventor, mechanical engineer, and rangaku scholar who was prominent during the Bakumatsu and early Meiji period in Japan. In 1875, he founded what became the Toshiba Corporation. He has been called the "Thomas ...

in 1851. It belongs to the category of Japanese clocks called '' Wadokei''. This clock is designated as an Important Cultural Property and a Mechanical Engineering Heritage by the Japanese government. The clock is driven by a spring. Once it is fully wound, it can work for one year without another winding. It can show the time in 7 ways (such as usual time, the day of the week, month, moon phase, Japanese time, Solar term). Since the time system in Japan at that time was temporal hour, a day was 12 hours, and a day was divided into day and night, and each divided into 6 equal parts was regarded as 1 hour. Because the length of the day and night changes according to the season, the time dial was automatically movable, and it was linked with the other six clocks, making it an extremely complicated mechanism. It also rings chimes every hour. It consists of more than 1,000 parts to realize these complex functions, and it is said that Tanaka made all the parts by himself with simple tools such as files and saws. It took more than three years for him to finish the assembly. In 2004 the Japanese government funded a project aimed at making a copy of this clock. More than 100 engineers joined the project and it took more than 6 months with the latest industrial technologies. However, even then it was not possible to make exact copies of some parts, such as the brass metal plate used as its spring, before the presentation at Expo 2005. The original clock is displayed at the

National Museum of Nature and Science The is in the northeast corner of Ueno Park in Tokyo. The museum has exhibitions on pre-Meiji period, Meiji science in Japan. It is the venue of the taxidermied bodies of the legendary dogs Hachikō and Taro and Jiro. A life-size blue whale mod ...

, while a copy is at Toshiba Corporation. The clock was listed in the Japanese Mechanical Engineering Heritage as item No. 22 in 2007.

Notes

Sources

* Frumer, Yulia. Making Time: Astronomical Time Measurement in Tokugawa Japan. University of Chicago Press, 2019.

External links

National Project to Restore Man-nen Jimeisho
Individual clocks Japanese inventions Astronomical clocks {{Measurement-stub