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 (–) system is derived from
the position of the sun.
Dual hour: shí Each () was of the time between one midnight and the next, 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 " ().
Describing the time during daylight Both and were used to describe the time, through one of two ways: • Eight mode. Before the Tang dynasty, the were noted first, then each of the major were counted up to 8. Using the definition of
fēn as 14.4 seconds, each
miǎo was 144 milliseconds long.
Shùn and niàn In Buddhism, each
fen was subdivided into
shùn (), and
shùn were subdivided into
niàn (). The
Mahāsāṃghika, translated into Chinese as the
Móhēsēngzhī Lǜ (
Taishō Tripiṭaka 1425) describes several units of time, including
shùn or
shùnqǐng () 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 () which is 7.2 seconds long, a
luóyù () which is 2 minutes 24 seconds long, and a
xūyú (), which is of a day at 48 minutes long.
During night: gēng-diǎn system The
Gēng-diǎn (–) system uses predetermined signals to define the time during the night.
One-tenth of a day: gēng Gēng () 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 , 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 central 1 , or 19:12. The time between each
gēng is 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:
yì gēng () (alternately
chū gēng () for "initial watch");
èr gēng ();
sān gēng ();
sì gēng (); and
wǔ gēng (). 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 (); midmorning, (); noon, (); afternoon (); and evening (). 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. The Xia Calendar (), introduced in 102 AD, added or subtracted a to the start of night whenever the sun moved 2.5° north or south from its previous position.
Traditional units in context ==Modern applications==