How was the ancient time calculated?

First of all, the calculation of ancient time

1, China ancient people kept diaries every day mainly by 16 hour system, 10 hour system, 100 hour system, 12 hour system, and the 60-point method introduced with Buddhism. Among them, the twelve-hour system is the most widely used.

Twelve o'clock Twelve time nodes (starting points) are twelve o'clock. In the Han dynasty, it was named midnight, crow, pingdan, sunrise, food time, corner, day, sundial, sunset, dusk and people's decision.

With the diversification of people's work and life, the words are gradually unsatisfactory, so they are represented by twelve earthly branches, 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

At midnight, it is ugly from 23: 00 to 1: 00, 1: 00 to 3: 00, Yin Shi from 3: 00 to 5: 00, Shi Mao from 5: 00 to 7: 00, Chen Shi from 7: 00, and so on.

Second, the definition of years, months and days 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 (taking the sun as a reference, the actual moon orbits more than once). ) is January, which is a calendar based on the moon. There are twelve calendar months in a year.

In the process of calendar development and evolution, the emergence of 24 solar terms was used to guide agricultural production scientifically, 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 road are two great circles on the celestial body, which intersect at five degrees and nine minutes. The moon goes around the earth once, and those moons that appear on the ecliptic twice. The calendar on the 27th is 7 hours and 43 minutes 1 1.5 seconds, which is called "sidereal moon".

Only when the moon revolves around the earth, the position of the earth changes, counting forward more than 27 degrees, and the moon runs at the speed of 13 degrees 15 minutes every day, so it takes 29 days 12: 44: 2.8 to return to the moon. This is called "the first moon", which is called a month by custom, meaning

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; "Reed" is a stone slab extending horizontally from the heel of the watch to the north.

Whenever the sun turns due south, the shadow will fall 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 winter solstice is here; At the shortest time, the summer solstice came. It is the oldest and most familiar astronomical instrument in China.

Second, carving and leakage.

Engraved leakage is also called engraved leakage and leaky pot. There are two main types of clepsydra: drainage type and water receiving type. Most early leaks are drainage type. Water leaks from the bottom side of the leaky kettle, and the lattice fork and the closing tongue rise again, so that the leaky arrow floating on the surface of the leaky kettle falls with the water surface, and the time is indicated by the scale on the leaky arrow.

Later, the water receiving type was created. Water is injected from the leaky kettle into the receiving kettle at a constant flow rate. As the water level rises, the leaking arrow floating on the water surface of the receiving kettle indicates the time, which improves the timing accuracy.

Third, the hourglass

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

Song Lian (1310 ~1381) wrote Song Shi Xue Ji, which recorded the structure of the hourglass, 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 that operates by water power, which can 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 rotate 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 delicate and complicated than Zhang Heng's water transport armillary sphere.

Therefore, when the water armillary sphere was made, it was placed in front of Wucheng Hall and watched by civil and military officials. They were all beautifully made, and it was amazing to measure Wang Shuo and accurately report the time.