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2FTraditional Japanese Clocks

Introduction of this section
Here we are exhibiting various Traditional Japanese Clocks or Wadokei, made during the Edo era, when the seasonal time system was in operation. In this system, each year was devived into 24 seasons. Both day and night were defined by sunrise and sunset, and split into six equal hours, so that the length of one hour in both day and night changes from season to season. During the Edo period, many different types of clocks were made with full of Japanese ideas to tell time using this system. These clocks were rendered redundant after 1873, when the fixed time system was adopted.
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Lantern Clock with Double Foliot Balance

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Automatic switching between day & night
This is a Lantern Clock with a Double Foliot Balance, made in the mid Edo era. The weight-driven double foliot balance clock automatically switched over two foliot balances at sunrise and sunset, by incorporating automatic arms connected with the hour wheel, so that adjustment of the position of the two weights of each balance was required only once every season or every two weeks, so as to regulate the speed of the wheels and the hand. In contrast, the conventional single foliot balance clock required the repositioning of the two weights twice a day, at both sunrise and sunset. This clock is also equipped with an hourly striking bell and alarm function. Wadokei manufacturing during the Edo era required very high technology and great skills and it is widely believed that this resource was a major factor behind Japan's rapid industrial development during the Meiji Restoration and later.