astronomy

Traditional Chinese timekeeping

Traditional Chinese timekeeping is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Traditional Chinese timekeeping rather than just read about it. In short: Traditional Chinese timekeeping refers to the time standards for divisions of the day used in China until the introduction of the Shixian calendar in 1644 at the beginning of the Qing dynasty. Han-era system Dating from the Han dynasty, the third chapter of the Huainanzi outlines 15 hours of daylight.

Key takeaways

Traditional Chinese timekeeping belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Traditional Chinese timekeeping to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Traditional Chinese timekeeping from memory before moving on to harder problems.

Reference excerpt

Traditional Chinese timekeeping refers to the time standards for divisions of the day used in China until the introduction of the Shixian calendar in 1644 at the beginning of the Qing dynasty.

Han-era system Dating from the Han dynasty, the third chapter of the Huainanzi outlines 15 hours of 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; 縣東), twilight (黄昏; 黃昏), rest time (定昏). These correspond to each hour from 06:00 to 20:00 on the 24-hour clock.

Eastern Han to Ming system The system used between the Eastern Han and Ming dynasties comprised 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.

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, 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, with midnight at the beginning. Starting from the end of the Tang dynasty into the Song dynasty, each shí was divided in half, with the first half called the initial hour (初) and the second called the central hour (正). The change of the midnight hour in the Song dynasty could thus be stated as going 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. kè literally means "mark" or "engraving", referring to the marks placed on sundials or water clocks 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 contains 81⁄3 kè, with 7 or 8 full kè and partial beginning or ending kè. These fractional kè are multiples of 1⁄6 kè, or 2 minutes 24 seconds. 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).

Describing the time during daylight Both shí and kè were used to describe the time, through one of two ways:

Eight kè mode. Before the Tang dynasty, the shí were noted first, then each of the major kè were counted up to 8. As an example, counting by major kè from the first shí to the second: zǐ (子), zǐ yī kè (子一刻), zǐ èr kè (子二刻), zǐ sān kè (子三刻), zǐ sì kè (子四刻), zǐ wǔ kè (子五刻), zǐ liù kè (子六刻), zǐ qī kè (子七刻), zǐ bā kè (子八刻), chǒu (丑). The time xū yī kè (戌一刻) would be read as "1 kè after xū shí", making the time 19:14:24. Four kè mode. After the Tang dynasty's division of the shí, it 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. This changes the first example above to: 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 (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). The time sì central 3 kè (巳正三刻) would be read as "the third kè in the second half of sì", corresponding to the time 11:31:12.

Smaller time units

Fēn kè were subdivided into smaller units, called fēn (分). The number of fēn in each kè varied over the centuries, but a fēn was generally defined as 1⁄6000 of a day. 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) subdivided each fēn into 100 miǎo (秒). Using the definition of fēn as 14.4 seconds, each miǎo was 144 milliseconds long.

Shùn and niàn

In Buddhism, each fēn 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. 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.

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 gēng in the night are numbered from one to five: yì 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. The gēng during daytime are morning (朝); midmorning, (禺); noon, (中); afternoon (晡); and evening (夕). 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.

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.

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Traditional Chinese timekeeping

Start with the simplest possible case. Write down what Traditional Chinese timekeeping claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Traditional Chinese timekeeping before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Traditional Chinese timekeeping ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Traditional Chinese timekeeping

In research: Traditional Chinese timekeeping appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Traditional Chinese timekeeping in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Traditional Chinese timekeeping is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomy in China, Decimal time, Metrication, so understanding it makes those chapters shorter.
In everyday life: Look for Traditional Chinese timekeeping outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Traditional Chinese timekeeping in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Traditional Chinese timekeeping means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Traditional Chinese timekeeping out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Traditional Chinese timekeeping in simple terms?

Traditional Chinese timekeeping refers to the time standards for divisions of the day used in China until the introduction of the Shixian calendar in 1644 at the beginning of the Qing dynasty. Han-era system Dating from the Han dynasty, the third chapter of the Huainanzi outlines 15 hours of daylig…

Why does Traditional Chinese timekeeping matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Traditional Chinese timekeeping?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Traditional Chinese timekeeping.