Traditional Chinese timekeeping 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.
Dating from the Han dynasty, the third chapter of the Huainanzi outlines 15 hours of daylight. These are dawn (), morning light (), daybreak (), early meal (), feast meal (), before noon (), noon (), short shadow (), evening (), long shadow (), high setting (), lower setting(), sunset (), twilight (), rest time (). These correspond to each hour from 06:00 to 20:00 on the 24-hour clock.
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 shÃÂ-kè standard, and at night were measured using the gÃÂng-diÃÂn standard.
The (–) system is derived from the position of the sun.
Each () was 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 . This first 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 was divided in half, with the first half called the initial hour () and the second called the central hour (). The change of the midnight hour in the Song dynasty could thus be stated as going from the central hour of the first () to the initial hour of the first ().
Days were also divided into smaller units, called (). One was usually defined as of a day until 1628, though there were short periods before then where days had 96, 108 or 120 . literally means "mark" or "engraving", referring to the marks placed on sundials or water clocks to help keep time.
Using the definition of as of a day, each is equal to 0.24 hours, 14.4 minutes, or 14 minutes 24 seconds. Every contains 8 , with 7 or 8 full and partial beginning or ending . These fractional are multiples of , or 2 minutes 24 seconds. The 7 or 8 full within each were referred to as "major " (). Each of a was called a "minor " ().
Both and were used to describe the time, through one of two ways:
were subdivided into smaller units, called fÃÂn (). The number of fÃÂn in each varied over the centuries, but a fÃÂn was generally defined as of a day. Using this definition, one fÃÂn is equal to 14.4 seconds. This also means that a fÃÂn is of a major and of a minor .
In 1280, Guo Shoujing's ShòushàCalendar () subdivided each fÃÂn into 100 miÃÂo (). Using the definition of fÃÂn as 14.4 seconds, each miÃÂo was 144 milliseconds long.
In Buddhism, each fen was subdivided into shùn (), and shùn were subdivided into niàn ().
The MahÃÂsÃÂá¹Âghika, translated into Chinese as the MóhÃÂsÃÂngzhë Là(Taishà  Tripiá¹Âaka 1425) describes several units of time, including shùn or shùnqÃÂng () 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 tánzhà() which is 7.2 seconds long, a luóyù () which is 2 minutes 24 seconds long, and a xà «yú (), which is of a day at 48 minutes long.
The GÃÂng-diÃÂn (–) system uses predetermined signals to define the time during the night.
GÃÂng () 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 gÃÂng , literally meaning "rotation" or "watch", comes from the rotation of watchmen sounding these signals.
The first gÃÂng theoretically comes at sundown, but was standardized to fall at central 1 , or 19:12. The time between each gÃÂng is of a day, making a gÃÂng 2.4 hoursâÂÂor 2 hours 24 minutesâÂÂlong.
The 5 gÃÂngs in the night are numbered from one to five: yì gÃÂng () (alternately chà « gÃÂng () for "initial watch"); èr gÃÂng (); sÃÂn gÃÂng (); sì gÃÂng (); and wàgÃÂng (). The 5 gÃÂngs 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 (); midmorning, (); noon, (); afternoon (); and evening ().
As a 10-part system, the gÃÂng are strongly associated with the 10 celestial stems, especially since the stems are used to count off the gÃÂng during the night in Chinese literature.
DiÃÂn (), or point, marked when the bell time signal was rung. The time signal was released by the drum tower or local temples.
Each diÃÂn or point is of a day, making them 0.4 hours, or 24 minutes, long. Every sixth diÃÂn falls on the gÃÂng, with the rest evenly dividing every gÃÂng into 6 equal parts.
GÃÂng and diÃÂn were used together to precisely describe the time at night.
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. The official start of night thus had a variation from 0 to 1 gÃÂng.
This variation was handled in different ways. From the start of the Western Han dynasty in 206 BC until 102 AD, yìgÃÂng was moved back one every 9th day from the winter solstice to the summer solstice, and moved forward one every 9th day from summer solstice to the winter solstice. The Xia Calendar (), introduced in 102 AD, added or subtracted a to the start of night whenever the sun moved 2.5ð north or south from its previous position.
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Chinese still uses characters from these systems to describe time, even though China has changed to the UTC standards of hours, minutes, and seconds.
is still used to describe the hour. Because of the potential for confusion, xiÃÂoshà(, literally "small hour") is sometimes used for the hour as part of a 24-hour cycle, and shÃÂchen () is used for the hour as part of the old 12-hour cycle. DiÃÂn is also used interchangeably with for the hour. It can also be used to talk about the time on the hourâÂÂfor example, 8 o' clock is written as 8 diÃÂn ().
FÃÂn is now the standard term for the minute. Sometimes the word fÃÂnzhà Âng () is used to clarify that one is talking about modern minutes. The time 09:45 can thus be written as "9 , 45 fÃÂn" () or "9 diÃÂn, 45 fÃÂn" ().
has been defined as of a day since 1628, so the modern equals 15 minutes and each double hour contains exactly 8 . Since then, has been used as shorthand to talk about time in of a double hour or 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 diÃÂn, 3 " ().
MiÃÂo is now the standard term for a second. Like fÃÂn, it is sometimes written as miÃÂozhà Âng () to clarify that someone is talking about modern seconds.