LANTERN CLOCK Ca. 1770 Japan
The weight-driven movement is constructed between vertical bars and consists of going, striking and alarm trains. The going train has a vertical verge escapement and foliot. The movement can be regulated by moving the weights on the foliot. The striking, which is regulated by a count wheel, indicates the hours on a bell.
The copper dial plate has a copper alarm disc in the middle with holes to set the alarm. The time is indicated by a fixed steel hand in the shape of a flower. The painted outer black chapter ring is divided into 12 hours, revolving fully in 24 hours and indicating the time with red hour numerals and signs of the Zodiac. The inner track of the chapter ring is divided into 2 x 6 toki from 4 to 9, also with engraved Japanese characters.
The copper case has steel bottom and top plates, between which the steel movement is constructed. Front and back, as well as the side doors are made of copper and situated between the top and bottom plates. The clock is surmounted by a bell, embellished with a shaped top ornament and secured with a nut.
Duration 1 day
Height 2.5 cm.
Width 9.5 cm.
Depth 9 cm.
– W. Brandes, Alte Japanische Uhren.
– N.H.N. Mody, Japanese clocks.
Japanese timekeeping was very different from timekeeping in the western world. Instead of the hour having a fixed value, the length of an hour in Japan, called toki in Japanese, varies according to the length of day and night. Both day and night are divided into 6 toki, spread over the period from sunrise to sunset and from sunset to sunrise. In summer the days are longer than the nights and therefore a toki during the day is longer than one during the night. In winter this is the other way around. For this reason Japanese clocks have chapter rings with movable chapters, so that the length of the toki can be modified. There are also clocks with a fixed chapter ring. In this case the clock’s beat rate changes by moving the weights on the foliot to slow down or accelerate the clock. This is seen mainly in older clocks.
The numerals on the clocks run from 9 to 4. In Japan number 9 was holy. Each toki, 12 in total, also had its own zodiacal symbol which is depicted on the chapter ring, around the hour numerals.