Traditional Chinese timekeeping

The traditional Chinese time systems refers to the time standards for divisions of the day used in China until the introduction of the Shixian calendar in 1628 at the beginning of the Qing dynasty.[1][2]

Explanatory Chart for Chinese time

Han-era system

The third chapter of the Huainanzi outlines 15 hours during daylight. These are dawn (晨明), morning light (朏明), daybreak (旦明), early meal (早食; 蚤食), feast meal (宴食), before noon (隅中), noon (正中), short shadow (少还; 小還), evening (𫗦时; 餔時; 'evening mealtime'), long shadow (大还; 大還), high setting (高舂), lower setting(下舂), sunset (县东; 縣車), twilight (黄昏; 黃昏), rest time (定昏).[3] These are correlated to each hour from 06:00 to 20:00 on the 24-hour clock.

East Han to Ming system

This system used two standards to measure the time in a solar day. Times during daylight were measured in the Shí-kè standard, and at night were measured using the Gēng-diǎn standard.

Stems & Branches in traditional Chinese time

Heavenly stems					Earthly branches
	Stem		Gēng			Branch		Shí (traditional)	Shí (Song dynasty)
1	jiǎ	甲	19:12	yīgēng	1	zǐ	子	23:00	00:00
2	yǐ	乙	21:36	èrgēng	2	chǒu	丑	01:00	02:00
3	bǐng	丙	00:00	sāngēng	3	yín	寅	03:00	04:00
4	dīng	丁	02:24	sìgēng	4	mǎo	卯	05:00	06:00
5	wù	戊	04:48	wǔgēng	5	chén	辰	07:00	08:00
6	jǐ	己	07:12	morning	6	sì	巳	09:00	10:00
7	gēng	庚	09:36	midmorning	7	wǔ	午	11:00	12:00
8	xīn	辛	12:00	noon	8	wèi	未	13:00	14:00
9	rén	壬	14:24	late afternoon	9	shēn	申	15:00	16:00
10	guì	癸	16:48	evening	10	yǒu	酉	17:00	18:00
					11	xū	戌	19:00	20:00
					12	hài	亥	21:00	22:00

During daylight: Shí-kè

The Shí-kè (時 - 刻) system is derived from the position of the sun.

Dual hour: Shí

Each shí (時; 时) was ​¹⁄₁₂ of the time between one midnight and the next,[2] making it roughly double the modern hour. These dual hours are named after the earthly branches in order, with midnight in the first shí. This first shí traditionally occurred from 23:00 to 01:00 on the 24-hour clock, but was changed during the Song dynasty so that it fell from 00:00 to 02:00.[2]

Starting from the end of the Tang Dynasty into the Song Dynasty, each shí was divided into two, with the first half of each shí called the initial hour (初) and the second called the central hour (正).[2] Using the change of the midnight hour and the first shí above, you could say that during the Song Dynasty midnight went from the central hour of the first shí (子正) to the initial hour of the first shí (子初).

One-hundredth of a day: Kè

Days were also divided into smaller units, called kè (刻). One kè was usually defined as ​¹⁄₁₀₀ of a day until 1628, though there were short periods before then where days had 96, 108 or 120 kè.[2] Kè literally means "mark" or "engraving", referring to the marks placed on sundials[4] or water clocks[5] to help keep time.

Using the definition of kè as ​¹⁄₁₀₀ of a day, each kè is equal to 0.24 hours, 14.4 minutes, or 14 minutes 24 seconds. Every shí will contain 8​¹⁄₃ kè, with 7 or 8 full kè and partial beginning and/or ending kè. These fractional kè are multiples of ​¹⁄₆ kè, or 2 minutes 24 seconds.[lower-alpha 1] The 7 or 8 full kè within each shí were referred to as "major kè" (大刻). Each ​¹⁄₆ of a kè was called a "minor kè" (小刻).[6]

Describing the time during daylight

Both shí and kè would be used to describe the time accurately. There are two ways of doing this.

1. Eight kè mode. Before the Tang dynasty, the shí were noted first, then each of the major kè were counted up to 8.[6]
   1. As an example, counting by major kè from the first shí to the second would look like this: zǐ (子), zǐ 1 kè (子一刻), zǐ 2 kè (子二刻), zǐ 3 kè (子三刻), zǐ 4 kè (子四刻), zǐ 5 kè (子五刻), zǐ 6 kè (子六刻), zǐ 7 kè (子七刻), zǐ 8 kè (子八刻), chǒu. (丑).
   2. Given the time xū 1 kè (戌一刻), this would be read as "1 kè after xū shí", making the time 20:09:36.
2. Four kè mode. After the Tang dynasty's introduction of "initial" and "central" parts of the shí, the shí was still noted first, but with an added description of which half of the shí the kè was taking place in. Since this narrowed the range of the possible major kè down to four, it was only necessary to specify the major kè between one and four.[6]
   1. This would change our first example above to look like this: zǐ initial (子初), zǐ initial 1 kè (子初一刻), zǐ initial 2 kè (子初二刻), zǐ initial 3 kè (子初三刻), zǐ initial 4 kè (子初四刻), zǐ central[lower-alpha 2] (子正), zǐ central 1 kè (子正一刻), zǐ central 2 kè (子正二刻), zǐ central 3 kè (子正三刻), zǐ central 4 kè (子正四刻), chǒu initial (丑初).
   2. Given the time sì central 3 kè (巳正三刻), this would be read as "the third kè in the second half of sì", making the time 11:31:12.

Fēn

Kè were subdivided into smaller units, called fēn (分). The number of fēn in each kè varied over the centuries,[2] but a fēn was generally defined as ​¹⁄₆₀₀₀ of a day.[6] Using this definition, one fēn is equal to 14.4 seconds. This also means that a fēn is ​¹⁄₆₀ of a major kè and ​¹⁄₁₀ of a minor kè.

Miǎo

In 1280, Guo Shoujing's Shòushí Calendar (授时曆) had each fēn subdivided into 100 miǎo (秒).[7] Using the definition of fēn as 14.4 seconds, each miǎo was 144 milliseconds long.

Shùn and niàn

Each fen was subdivided into shùn (瞬), and shùn were subdivided into niàn (念).

The Mahāsāṃghika, translated into Chinese as the Móhēsēngzhī Lǜ (Taishō Tripiṭaka 1425) describes several units of time, including shùn or shùnqǐng (瞬頃; 'blink moment') and niàn. According to this text, niàn is the smallest unit of time at 18 milliseconds and a shùn is 360 milliseconds.[8] It also describes larger units of time, including a tánzhǐ (彈指) which is 7.2 seconds long, a luóyù (羅豫) which is 2 minutes 24 seconds long, and a xūyú (須臾), which is ​¹⁄₃₀ of a day at 48 minutes long.[lower-alpha 3]

During night: Gēng-diǎn system

The Gēng-diǎn (更 - 點) system uses predetermined signals to define the time during the night.

One-tenth of a day: Gēng

Gēng (更) is a time signal given by drum or gong. The drum was sounded by the drum tower in city centers, and by night watchman hitting a gong in other areas. The character for gēng 更, literally meaning "rotation" or "watch", comes from the rotation of watchmen sounding these signals.

The first gēng theoretically comes at sundown, but was standardized to fall at yǒu shí central 1 kè, or 19:12. The time between each gēng is ​¹⁄₁₀ of a day, making a gēng 2.4 hours—or 2 hours 24 minutes—long.

The 5 gēngs in the night are numbered from one to five: yī gēng (一更) (alternately chū gēng (初更) for "initial watch"); èr gēng (二更); sān gēng (三更); sì gēng (四更); and wǔ gēng (五更). The 5 gēngs in daytime are named after times of day listed in the Book of Sui, which describes the legendary Yellow Emperor dividing the day and night into ten equal parts. They are morning (朝); midmorning, (禺); noon, (中); afternoon (晡); and evening (夕).[9]

As a 10-part system, the gēng are strongly associated with the 10 celestial stems, especially since the stems are used to count off the gēng during the night in Chinese literature.[9]

One-sixtieth of a day: Diǎn

Diǎn (点; 點), or point, marked when the bell time signal was rung. The time signal was released by the drum tower or local temples.

Each diǎn or point is ​¹⁄₆₀ of a day, making them 0.4 hours, or 24 minutes, long. Every sixth diǎn falls on the gēng, with the rest evenly dividing every gēng into 6 equal parts.

Describing the time during the night

Gēng and diǎn were used together to precisely describe the time at night.

Counting from the first gēng to the next would look like this: yīgēng (一更), yīgēng 1 diǎn (一更一点; 一更一點), yīgēng 2 diǎn (一更二点; 一更二點), yīgēng 3 diǎn (一更三点; 一更三點), yīgēng 4 diǎn (一更四点; 一更四點), yīgēng 5 diǎn (一更五点; 一更五點), èrgēng (二更).

Given the time sāngēng 2 diǎn (三更二点; 三更二點), you would read it as "two diǎn after sāngēng", and find the time to be 00:48.[lower-alpha 4]

The night length is inconsistent during a year. The nineteenth volume of the Book of Sui says that at the winter solstice, a day was measured to be 60% night, and at the summer solstice, only 40% night.[10] The official start of night thus had a variation from 0 to 1 gēng.

This variation was handled in different ways. From the start of the Western Han dynasty in 206 BC until 102 AD, yīgēng was moved back one kè every 9th day from the winter solstice to the summer solstice, and moved forward one kè every 9th day from summer solstice to the winter solstice.[10] The Xia Calendar (夏历; 夏曆), introduced in 102 AD, added or subtracted a kè to the start of night whenever the sun moved 2.5° north or south from its previous position.[10]

Traditional units in context

Relationships between traditional Chinese time units

Diǎn	00:00:00 Sāngēng										00:24:00 Sāngēng 1 diǎn										00:48:00 Sāngēng 2 diǎn										01:12:00 Sāngēng 3 diǎn										01:36:00 Sāngēng 4 diǎn										02:00:00 Sāngēng 5 diǎn										02:24:00 Sìgēng										02:48:00 Sìgēng 1 diǎn										03:12:00 Sìgēng 2 diǎn										03:36:00 Sìgēng 3 diǎn										04:00:00 Sìgēng 4 diǎn										04:24:00 Sìgēng 5 diǎn										04:48:00 Wǔgēng										05:12:00 Wǔgēng 1 diǎn										05:36:00 Wǔgēng 2 diǎn										06:00:00 Wǔgēng 3 diǎn										06:24:00 Wǔgēng 4 diǎn										06:48:00 Wǔgēng 5 diǎn										07:12:00 Morning										07:36:00 Morning 1 diǎn										08:00:00 Morning 2 diǎn										08:24:00 Morning 3 diǎn										08:48:00 Morning 4 diǎn										09:12:00 Morning 5 diǎn										09:36:00 Midmorning										10:00:00 Midmorning 1 diǎn										10:24:00 Midmorning 2 diǎn										10:48:00 Midmorning 3 diǎn										11:12:00 Midmorning 4 diǎn										11:36:00 Midmorning 5 diǎn										12:00:00 Noon										12:24:00 Noon 1 diǎn										12:48:00 Noon 2 diǎn										13:12:00 Noon 3 diǎn										13:36:00 Noon 4 diǎn										14:00:00 Noon 5 diǎn										14:24:00 Afternoon										14:48:00 Afternoon 1 diǎn										15:12:00 Afternoon 2 diǎn										15:36:00 Afternoon 3 diǎn										16:00:00 Afternoon 4 diǎn										16:24:00 Afternoon 5 diǎn										16:48:00 Evening										17:12:00 Evening 1 diǎn										17:36:00 Evening 2 diǎn										18:00:00 Evening 3 diǎn										18:24:00 Evening 4 diǎn										18:48:00 Evening 5 diǎn										19:12:00 Yīgēng										19:36:00 Yīgēng 1 diǎn										20:00:00 Yīgēng 2 diǎn										20:24:00 Yīgēng 3 diǎn										20:48:00 Yīgēng 4 diǎn										21:12:00 Yīgēng 5 diǎn										21:36:00 Èrgēng										22:00:00 Èrgēng 1 diǎn										22:24:00 Èrgēng 2 diǎn										22:48:00 Èrgēng 3 diǎn										23:12:00 Èrgēng 4 diǎn										23:36:00 Èrgēng 5 diǎn
Gēng	00:00:00 Sāngēng																																																												02:24:00 Sìgēng																																																												04:48:00 Wǔgēng																																																												07:12:00 Morning																																																												09:36:00 Midmorning																																																												12:00:00 Noon																																																												14:24:00 Afternoon																																																												16:48:00 Evening																																																												19:12:00 Yīgēng																																																												21:36:00 Èrgēng
Kè (only major kè)	00:00:00						00:14:24						00:28:48						00:43:12						00:57:36						01:12:00						01:26:24						01:40:48						01:55:12						02:09:36						02:24:00						02:38:24						02:52:48						03:07:12						03:21:36						03:36:00						03:50:24						04:04:48						04:19:12						04:33:36						04:48:00						05:02:24						05:16:48						05:31:12						05:45:36						06:00:00						06:14:24						06:28:48						06:43:12						06:57:36						07:12:00						07:26:24						07:40:48						07:55:12						08:09:36						08:24:00						08:38:24						08:52:48						09:07:12						09:21:36						09:36:00						09:50:24						10:04:48						10:19:12						10:33:36						10:48:00						11:02:24						11:16:48						11:31:12						11:45:36						12:00:00						12:14:24						12:28:48						12:43:12						12:57:36						13:12:00						13:26:24						13:40:48						13:55:12						14:09:36						14:24:00						14:38:24						14:52:48						15:07:12						15:21:36						15:36:00						15:50:24						16:04:48						16:19:12						16:33:36						16:48:00						17:02:24						17:16:48						17:31:12						17:45:36						18:00:00						18:14:24						18:28:48						18:43:12						18:57:36						19:12:00						19:26:24						19:40:48						19:55:12						20:09:36						20:24:00						20:38:24						20:52:48						21:07:12						21:21:36						21:36:00						21:50:24						22:04:48						22:19:12						22:33:36						22:48:00						23:02:24						23:16:48						23:31:12						23:45:36
Shí (post-Tang)	00:00:00 Zǐ initial																									01:00:00 Zǐ central																									02:00:00 Chǒu initial																									03:00:00 Chǒu central																									04:00:00 Yín initial																									05:00:00 Yín central																									06:00:00 Mǎo initial																									07:00:00 Mǎo central																									08:00:00 Chén initial																									09:00:00 Chén central																									10:00:00 Sì initial																									11:00:00 Sì central																									12:00:00 Wǔ initial																									13:00:00 Wǔ central																									14:00:00 Wèi initial																									15:00:00 Wèi central																									16:00:00 Shēn initial																									17:00:00 Shēn central																									18:00:00 Yǒu initial																									19:00:00 Yǒu central																									20:00:00 Xū initial																									21:00:00 Xū central																									22:00:00 Hài initial																									23:00:00 Hài central
Shí (ancient)	00:00:00 Zǐshí																									01:00:00 Chǒushí																																																		03:00:00 Yínshí																																																		05:00:00 Mǎoshí																																																		07:00:00 Chénshí																																																		09:00:00 Sìshì																																																		11:00:00 Wǔshí																																																		13:00:00 Wèishí																																																		15:00:00 Shēnshí																																																		17:00:00 Yǒushí																																																		19:00:00 Xūshí																																																		21:00:00 Hàishí																																																		23:00:00 Zǐshí

Modern applications

Chinese still uses characters from these systems to describe time, even though China has changed to the UTC standards of hours, minutes, and seconds.

Shí is still used to describe the hour. Because of the potential for confusion, xiǎoshí (小时; 小時, literally "small hour") is sometimes used for the hour as part of a 24-hour cycle, and shíchen (时辰; 時辰) is used for the hour as part of the old 12-hour cycle.

Diǎn is also used interchangeably with shí for the hour. It can also be used to talk about the time on the hour—for example, 8 o' clock is written as 8 diǎn (八点; 八點).

Fēn is also used for minutes. To avoid confusion, sometimes the word fēnzhōng (分钟; 分鐘, literally "clock minute") is used to clarify that one is talking about modern minutes. The time 09:45 can thus be written as "9 shí, 45 fēn" (九时四十五分; 九時四十五分) or "9 diǎn, 45 fēn" (九点四十五分; 九點四十五分).

Kè has been defined as ​¹⁄₉₆ of a day since 1628, so the modern kè equals 15 minutes and each double hour contains exactly 8 kè.[2] Since then, kè has been used as shorthand to talk about time in ​¹⁄₈ of a double hour or ​¹⁄₄ of a single hour. Their usage is similar to using "quarter hour" for 15 minutes or "half an hour" for 30 minutes in English. For example, 6:45 can be written as "6 diǎn, 3 kè" (六点三刻; 六點三刻).

Miǎo is now the standard term for a second. Like fēn, it is sometimes written as miǎozhōng (秒钟; 秒鐘, literally "clock second") to clarify that someone is talking about modern seconds.

See also

• Chinese calendar
• Decimal time
• Hour
• Date and time notation in Asia
• Chinese units of measurement
• Chinese Buddhism, the texts from which the smallest units of traditional Chinese time are derived

Notes

1. 600 is the LCM of 100 and 24, so the time between kè and shí scale may be ​¹⁄₆, ​¹⁄₃, ​¹⁄₂, ​²⁄₃, or ​⁵⁄₆ major kè. The ​¹⁄₆ major kè is the common factor
2. Note that the beginning of the central hour doesn't occur at the same time as the fourth major kè. The difference between the start of the central hour and the fourth major kè is always between 1 and 5 minor kè.
3. This 30-part day is identical to the Hindu muhūrta.
4. This assumes that the diǎn haven't moved; or if they have, that sāngēng still falls at exactly midnight.

References

1. Kiyoshi Yabuuchi (1963). "Astronomical tables in China, from the Wutai to the Ch'ing dynasties". Japanese Studies in the History of Science. 2: 94–100. ISSN 0090-0176.
2. Sôma, Mitsuru; Kawabata, Kin-aki; Tanikawa, Kiyotaka (2004-10-25). "Units of Time in Ancient China and Japan". Publications of the Astronomical Society of Japan. 56 (5): 887–904. Bibcode:2004PASJ...56..887S. doi:10.1093/pasj/56.5.887. ISSN 0004-6264.
3. "Tiānwén xùn" 天文訓 [Patterns of Heaven]. Huainanzi. 日出于暘谷，浴于咸池，拂于扶桑，是謂晨明。
   登于扶桑，爰始將行，是謂朏明。
   至于曲阿，是謂旦明。
   至于曾泉，是謂蚤食。
   至于桑野，是謂晏食。
   至于衡陽，是謂隅中。
   至于昆吾，是謂正中。
   至于鳥次，是謂小還。
   至于悲谷，是謂餔時。
   至于女紀，是謂大還。
   至于淵虞，是謂高舂。
   至于連石，是謂下舂。
   至于悲泉，爰止其女，爰息其馬，是謂縣車。
   至于虞淵，是謂黃昏。
   至于蒙谷，是謂定昏。
4. Stephenson, F. Richard; Green, David A. (2002). Historical supernovae and their remnants. Oxford: Oxford University Press. pp. 15–16. ISBN 0-19-850766-6.
5. Xu Shen (ed.). "Volume eleven". Shuowen Jiezi. 漏：以銅受水，刻節，晝夜百刻。 Translation: The water clock holds the water in the copper pot, and marks the scale on the rule. There are 100 marks which represent a day.
6. 曆象彙編/曆法典/第099卷 [Calendar compilations/Calendar quotations/Volume 99]. Gujin Tushu Jicheng.
7. Martzloff, Jean-Claude (2000). "Chinese mathematical astronomy". In Selin, Helaine (ed.). Mathematics across cultures. Dordrecht: Kluwer. pp. 373–407. ISBN 0-7923-6481-3.
8. "Taishō Tripiṭaka 1425". Móhēsēngzhī Lǜ 摩訶僧祗律 [Mahāsāṃghika]. 須臾者，二十念名一瞬頃，二十瞬名一彈指，二十彈指名一羅豫，二十羅豫名一須臾。日極長時有十八須臾，夜極短時有十二須臾，夜極長時有十八須臾，日極短時有十二須臾。 Rough translation: Definition of xūyú: 20 niàn is 1 shùnqǐng. 20 shùn is 1 tánzhǐ. 20 tánzhǐ is one luóyù. 20 luóyù is one xūyú. In the longest day there are 18 xūyú, and in the shortest night there are 12 xūyú. In the shortest day there are 12 xūyú and in the longest night there are 18 xūyú.
9. "Zhì dì 14 tiānwén shàng" 志第14 天文上 [Treatise 14, On Astronomy]. Book of Sui. "Water clocks" (漏刻). 晝有朝，有禺，有中，有晡，有夕。夜有甲、乙、丙、丁、戊。 Rough translation: Daytime has morning, midmorning, noon, late afternoon, evening. Night has first, second, third, fourth, fifth.
10. Petersen, Jens Østergård (1992). "The Taiping Jing and the A.D. 102 Clepsydra Reform". Acta Orientalia. Copenhagen. 53: 122–158.

Bibliography

• Ronan, Colin (1999). "Astronomy in China, Korea and Japan". In Christopher Walker (ed.). Astronomy before the telescope. London: British Museum Press. pp. 247–250. ISBN 0-7141-2733-7.
• Stephenson, F. Richard (1997). Historical Eclipses and Earth's Rotation. Cambridge: Cambridge University Press. ISBN 9780521461948.