Ke (unit)

The traditional time system is the time system in ancient China. Shi-ke and G-P system are typical systems which were used in ancient China for over 2000 years. Shi-ke describes the time according to the readings on a time meter, such as sundial, ruler of the water clock, clock, etc. G-P system is describes the time according to a predetermined signal, such as a drum, bell, gong, or bioclock.

The shi-ke system is derived from time measurement. The shis are the scales on the sundial, and the kes are the scales on the sundial or ruler of the water clock.

時 shi are 12 milestones in a day, which are used to stamp the time. The 12 shi are: midnight, crowing, dawn, sunrise, breakfast, ante, noon, post, dinner, sunset, dusk, and quieting. The earthly branches are used to name the 12 shi: 子 zi, 丑 chou, 寅 yin, 卯 mao, 辰 chen, 巳 si, 午 wu, 未 wei, 申 shen, 酉 you, 戌 xu, 亥 hai. The time length of a shi is two hours.

The first shi covered the time around midnight from 23:00 to 1:00 until the Tang dynasty and from 0:00 to 2:00 during the Song dynasty.

The time between two scales is a centiday or 14.4 minutes (14 minutes 24 seconds). When the shi scales and centiday scales are marked on the ruler of the water clock, the shi scales are smaller, and be called as snicks. The time between the scales and snicks is the multiple of 2.4 minutes (2 minutes 24 seconds), which is the common factor time between centiday scale and shi scale.

Although the day was subdivided into 100 刻 ke, there were short periods in the Chinese history where there were 96, 108 or 120 ke.

The shi and ke are matched to describe the time. There're two expression mode:

The gongs are the drum/gong time signal. The time signal is drum beat by the Bell and Drum Tower in the city, and gong beat by watchman in the town. The first gong is at 1 ke, a.xu shi. The time between gong beats is 2.4 hours or a deciday. The 5 gongs in the night are named by number, such as yi, er, san, si, and wu. The 5 gongs in daytime are morn, ante, noon, post, and eve.

The points are the bell time signal. The time signal is released by the Bell and Drum Tower or temples. There are 60 points within a day.

Gong and point are matched to describe the time in the night.

Each ke was subdivided into 60 分 fen. Therefore, each shi consisted of 8 ke 20 fen (= 8 1/3 ke).

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