How is the ancient time calculated?

First, the calculation of ancient time.

1, China ancient people's daily diary methods mainly include 16: 00, 10: 00, 100: 00 and 12: 00, and the 60-point method introduced with Buddhism. Among them, the twelve-hour system is the most widely used.

Twelve time nodes (starting points) at twelve o'clock are twelve o'clock. In the Han Dynasty, it was named Midnight, Crow, Pingdan, Sunrise, Food Time, Horn, Japan-China, Sundial, Sunset, Dusk and Man's Decision.

With the diversification of people's work and life, their words are gradually unsatisfactory, so they are represented by twelve earthly branches, including eleven o'clock in the evening, one o'clock in the morning, three o'clock in the morning, five o'clock in the morning, seven o'clock in the morning, nine o'clock in the morning, eleven o'clock in the afternoon, three o'clock in the afternoon, five o'clock in the evening, seven o'clock in the evening and nine o'clock in the evening.

2. Conversion between twelve o'clock and twenty-four hours

Midnight 23:00- 1:00, 1:00-3:00 ugly, 3:00-5:00 Yin Shi, 5:00-7: 00 Shi Mao, 7:00 Chen Shi, and so on.

Second, the definition of age, month and day in ancient calendars

In ancient China, the lunar calendar was generally used. In astronomy, the lunar calendar mainly refers to the calendar arranged according to the moon phase cycle, in which the moon orbits the earth once (based on the sun, the actual moon orbits more than once). ) is January, that is, the calendar based on the moon, with twelve calendar months in a year.

In the process of calendar development and evolution, the emergence of 24 solar terms was used to scientifically guide agricultural production, and the lunar calendar (Han calendar) was formed.

The lunar calendar determines the moon according to the law of its movement: the orbit of the moon is called the white road, and both the white road and the ecliptic are two great circles on the celestial body, which intersect at five degrees and nine minutes. The moon goes around the earth and appears on the ecliptic twice, which lasts for 7 hours and 43 minutes 1 1.5 seconds on the 27th, and is called "Stellar Moon".

Only when the moon revolves around the earth, the position of the earth also changes. The forward count is more than 27 degrees, and the moon runs 13 degrees 15 minutes every day, so it takes 12: 44: 2.8 to return to the moon on the 29th, which is called "the first moon", and it is called the moon according to custom, which means the first moon.

Extended data

Ancient timing tools

First of all, the standard table

A sundial is also called a sundial. The "table" in the standard table is a pole or stone pillar standing vertically on the ground; "Gui" is a slate extending horizontally from the heel of the watch to the north.

Whenever the sun turns due south, the shadow falls on the water of Guiyu. By measuring the length of the shadow, we can calculate the time of each solar term, such as winter solstice and summer solstice. When the shadow is the longest, the solstice of winter comes; In the shortest time, the summer solstice came. It is the oldest and most common astronomical instrument in China.

Second, lettering and missing words

Carving leakage is also called carving leakage and pot leakage. There are two main types of clepsydra: drainage type and water receiving type. Most of the early water leaks were drainage type. The bottom side of the leaky kettle leaks water, and the grid fork and the closing tongue rise again, so that the leaking arrow floating on the surface of the leaky kettle drops with the water surface, and the scale on the leaking arrow indicates the time.

Later, the water-receiving type was created. Water is injected from the leaky kettle into the receiving kettle at a constant flow rate, and the leaking arrow floating on the water surface of the receiving kettle indicates the time with the rise of the water surface, thus improving the timing accuracy.

Third, the hourglass

The hourglass is driven by quicksand, because it leaks in winter and freezes easily. Tian Wenzhi of Shi Ming records that Zhan Xiyuan created the "five-wheel hourglass" in the early days. Later, in order to prevent congestion, Zhou Shuxue enlarged the quicksand cave and replaced it with six wheels.

Song Lian (1310 ~1381) wrote "songji", which recorded the hourglass structure, with the size of parts and the number of teeth of each wheel of the reduction gear, and said that the shaft tip of the fifth wheel had no teeth, but it was equipped with a landscape disk indicating time.

Fourth, the water armillary sphere

Water-borne armillary sphere is an instrument which can run by water power, imitate the operation of celestial bodies and measure time. This armillary sphere improved the design of Zhang Heng, a scientist in Han Dynasty, and injected water into the wheel to make it turn day and night. Besides the movement of the stars, it can also show the rising of the sun and the setting of the moon. Of course, it is more exquisite and complicated than Zhang Heng's water transport armillary sphere.

Therefore, when making the water-borne armillary sphere, put it in front of the Wucheng Hall, and watch it by officials of civil and military affairs. All of them are beautifully made, and the measurement and timing of the northern moon are accurate, impressive and wonderful.