What tools were used to calculate time in ancient times?

The earliest timekeeping instrument used by human beings is to judge time by the projection length and direction of the sun. The former is called a standard watch, which is used to measure the time between Japan and China, determine the season and identify the direction; The latter is called a sundial and is used to measure time. Both are collectively referred to as sun clock.

sundial

A "standard watch" is a tool for measuring time by calculating the length of the sun shadow. It consists of two parts: the benchmark or stone pillar standing upright on the ground to measure the sun shadow is called the watch, and the rigid flat plate placed in the north and south to measure the sun shadow is called the watch. Time is also called "time", which refers to the shadow left by the sun on the ground. The word time has something to do with standards. The standard table is to determine the length of the noon shadow to determine the solar terms and the tropic year or solar calendar year. For a long historical period, the accuracy of the tropical year determined by China ranks first in the world. Through further research and calculation, ancient Han scholars also mastered the length of the sun shadow in the standard table of 24 solar terms. In this way, the standard table can not only be used to formulate festivals, but also be used to discharge the dates of the future solar calendar year and the twenty-four solar terms in the almanac, as an important basis for guiding the agricultural activities of the working people of the Han nationality.

sundial

On the basis of this standard, people invented the "sundial", also known as "sundial". The original meaning refers to the shadow of the sun or the projection of light to judge time. A sundial consists of hands and a dial engraved with lines. When the direction of the sun changes, the projection of the pointer on the dial points in different directions. According to long-term observation, the ancients established the position of the sun shadow corresponding to twelve o'clock, and judged the time accordingly. For example, "3 noon" refers to the third scale of the sundial at noon. This invention has been used by human beings for thousands of years.

Standard watches and sundials are both methods of timing by the sun. But how do you time when it rains? The ancients invented the method of "missing engraving". "Missing carving" is to use the principle of water balance to hold water in the pot and judge the time by observing the position of the ruler (called carving arrow) engraved with time on the pot. The method of "missing engraving" has been widely used in China for a long time because it is not affected by the weather and climate. China also had mechanical timers in ancient times. In Song Dynasty, Su Song rebuilt the water armillary sphere invented by Zhang Heng, which can accurately tell the time and display twelve o'clock.

Qi Yue

It is a sundial-like tool to indicate time. The most basic sundial is the same as the sundial, except that time can only be displayed correctly on a full moon night. Because the time of moonrise is delayed by 48 minutes on average every day, assuming there is enough moonlight reading time, the time indicated after the full moon will be 48 minutes faster on average every day. Therefore, a week before and after the full moon, the time displayed by the sundial will differ from the actual time by 5 hours and 36 minutes. More advanced sundials will include a chart showing how to calculate the correct time, and a turntable to adjust the longitude and latitude.

water clock

Also known as "leaky pot". According to the principle of isochronism, there are two kinds of dripping time: one is to record the time of water leakage with a special container (drainage type), and the other is to record how long it takes to fill with water with a container without an opening at the bottom (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.

Five-wheel hourglass

Also known as the sand clock, it is a device for measuring time. Because water freezes easily in winter, it is driven by quicksand. 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. The hourglass measures time by the time it takes a glass ball filled with sand to flow into the bottom glass ball from above through a narrow pipe. Once all the sand flows to the glass ball at the bottom, the hourglass can measure the time backwards. The nominal running time of an ordinary hourglass is 1 min.

Water transport altimeter

In ancient literature, Luo was said to be an armillary sphere of Emperor Wu of the Han Dynasty (140 ~ 87 BC), but its structure was not mentioned.

Jin Zhi records that Zhang Heng (AD 78 ~ 139) made the armillary sphere, saying that it was driven by water leakage in the secret room, and the time of the stars indicated by the instrument was consistent with the astronomical observation results.

The Book of the New Tang Dynasty, Tian Wen Zhi, records in detail the armillary sphere designed by the monks and their party by Liang Lingzan in the 13th year of Tang Kaiyuan (725). The instrument is equipped with two wheels, namely the sun and the moon, and the waterwheel drives the elephant. The elephant turns once a day and the sun turns 1/365 times. The instrument is also equipped with two puppets, which drum and carve respectively. This is a wooden building with a narrow bottom and a large width.

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.

In particular, there are two wooden figures on the water-borne armillary sphere, which are driven by gears. One wooden statue automatically rings the drum every moment (in ancient times, it was 100 minutes a day and night), and the other wooden statue automatically rings the bell every morning (now two hours). Of course, these two wooden figures should be said to be robots made by mechanical principles in ancient times. This is a very clever timing machine, the earliest mechanical clock device in the world and the ancestor of modern mechanical clocks. It was six centuries earlier than the wicker clock that appeared in the West in 1370, which fully showed the intelligence of the working people and scientists in ancient China.

Although this kind of water-borne armillary sphere was used for some time, it could not be rotated and entered the museum because of the gradual astringency of copper and iron. However, the monk, his party and Liang Lingzan went down in history forever because they got the invention right of astronomical clock. Dr Joseph Needham, a famous British historian of science and technology, said in the fourth volume of the History of Science and Technology in China: The parallel linkage device invented by monks and Liang Lingzan is essentially the earliest mechanical clock, the ancestor of all escapements, and the first mechanical clock in Europe before14th century; It is completely wrong to say that western clock devices were invented in Europe at the beginning of14th century.

The water-borne armillary sphere is engraved with 28 nights, and water is injected into the wheel once a day, which is exactly the same as the apparent motion of the celestial body on Sunday. Half of the water-borne armillary sphere is in the water tank, and the box on the water tank is like the ground, naturally ringing the bell. The whole water-borne armillary sphere can not only demonstrate the apparent motion of the sun, moon and stars, but also automatically tell the time. There are two Woodenhead, who play drums every moment (in ancient times, a day and night was divided into 100 minutes =0.24 hours = 14, 4 minutes) and ring the bell every hour (now it is two hours). This is the earliest application of escapement mechanism in timekeeping in the world, more than 600 years before the appearance of foreign chimes. A group of people have achieved more than Zhang Heng. It was also the first robot to tell the time.

A group of people observed the movements of the five stars of the sun, the moon and the ecliptic with the newly-made zodiac navigator, and measured the equatorial coordinates of some stars and their relative positions with the ecliptic. It was found that the positions of these stars changed greatly from those measured in the Han Dynasty.

Water transport image table

Yuan You three years in the Northern Song Dynasty (1088) was written by Su Song, Han Gonglian and others. In the early years of Shao Sheng's life (1094 ~ 1097), they wrote "An Outline of New Devices", which contained several general plans and component drawings. This watercraft is more than three feet high and two feet wide. This is a narrow and wide wooden building. There is a water lifting device on the lower floor of the platform, and the upper wheel and the lower wheel (pipe truck) are driven by manpower to lift the water to Tianhe (receiving pool) and inject it into Tianchi (reservoir). The water level of the flat kettle in the platform is kept constant, and a constant flow of water is discharged to the kettle on the pivot wheel (waterwheel) through a water pipe with a certain section to push the pivot wheel. The pivot wheel drives the day and night wheel, the elephant and the armillary sphere through the transmission gear.

There is a complex gear transmission system in the image platform of water transport instrument. There is a "Tianheng" device-escapement mechanism above and around the pivot wheel, which is the continuation of a great creation in the history of world timing machinery, and it turns the continuous rotation of the pivot wheel into intermittent rotation.

There is a "balance" device-escapement mechanism above and around the pivot wheel. This is a great creation in the history of timing machinery. It transforms the continuous rotating motion of the pivot wheel into intermittent rotating motion. The picture of "Tianheng" in the New Image Law does not show the pivot wheel and the kettle mounted on it, and the description in the book is only a few words: "The diameter of the pivot wheel is one foot and one foot, and 72 spokes are planted on a hub to make 36 floods and tie three rims. There are 36 pots in each flood, each pot is one foot long, five inches wide and four inches deep. " Put iron shifting teeth on the side of the pot to shift the balance and close the tongue. "So there are different speculations about the structure of the kettle, especially the working principle. One of them uses a tilting kettle. When the water in the kettle receiving water injection on the circumference of the pivot wheel is less than a certain weight, the left-hand lock blocks the spokes of the pivot wheel so that the pivot wheel cannot rotate. When the accumulated water reaches a certain weight, and the fulcrum weight (heavy hammer) is not enough to balance the gravity of the kettle, the kettle inclines downward around the rotating shaft. The iron shifting teeth installed on the side of the pot press the grid fork and the tongue to descend, and the tongue is driven by the ejector rod to lift the top door and the left top door lock, and the pivot wheel can rotate. After turning a kettle, the grid fork and the closing tongue rise again, the skylight and the left skylight lock fall, and the next pair of spokes of the pivot wheel are blocked again. The function of the right lock is to prevent the pivot wheel from bouncing when it rotates. Natural force and pivot force are two balancing forces. Tianquan is used to balance the partial gravity of the left Tissot and the crown, which can adjust the working sensitivity of the Tianheng mechanism. Pivot weight is used to adjust the period of intermittent movement when the pivot wheel rotates a pair of spokes, so as to correct the timing error.

? Xiangzhuanzhong

The ancient timer, a legend, is little known. According to the book Xiang Zhuan Zhong written by Xue, a scholar in the Song Dynasty, Xiang Zhuan Zhong was an ancient timepiece that was popular in China in the middle of A.D.12nd century. In the legend of the Emperor's Judgment, it is also described that the court in the Tang Dynasty used a seal clock to time: the seal clock is a plum-shaped brass plate with five plum blossoms in it, and each plum blossom is wrapped in a circle of incense. According to the burning degree of incense after burning, it is called "Five Pregnant Xiangyun".

A large number of lamps leak

1276, Guo Shoujing, a famous scientist in Yuan Dynasty, created the big leaky lamp. It is an automatic timer driven by water power, which drives the puppet to ring bells, engrave drums, ring cymbals, ring cymbals and ring cymbals through a gear train and a rather complicated cam mechanism. Because it looks like a palace lantern, it is placed in the Daming Hall of the Forbidden City, so it is called the Daming Hall.

In addition, there are timing tools such as oil lamp clock and candle clock. /kloc-after the 0/7th century, the west introduced more sophisticated clocks and watches, and people gradually gave up the original timing tools. In terms of timing method, the ancients used the centenary method, that is, a day and night were divided into centenary, and a moment was about 14.4 minutes. Twelve-hour timing was invented in Sui and Tang Dynasties. After the introduction of western clocks into China, in order to adapt to the 24-hour timing method, the hundred-engraving system was changed to 96-engraving system; An hour is two hours, and an hour is four quarters.

reference data

Zhihu, Zhihu [citation time 20 18-3-8]