What was the ancient tool for measuring time?

In ancient times, the inventor of the sundial was ominous. The sundial looks like a top with an iron or stone inserted on it. The stone indicates the scale on the wheel to know the time.

Then, the copper pot is used to time. It is said that the earliest copper pots were produced in the Zhou Dynasty and the Bronze Age. The copper pot is full of water. By dripping water and timing, there is a ruler on the copper pot, and the water level drops and the wood falls, indicating the corresponding time.

PS The following is the development process of timing tools.

From sundial to cesium atomic clock

In ancient times, people didn't have tools to measure time, but only judged time by the rise and fall of the sun, so there was a saying that "the sun rises and sets, and the sun sets". However, the Chinese nation is a nation full of wisdom. As early as the Zhou and Han Dynasties, there were instruments for measuring time. The earliest timer was a kind of water meter-clepsydra. According to Sui Zhi, "The system of missing carving began in the Yellow Emperor." It means it appeared early.

Split sundial

Another kind of timer, called sundial, is an iron needle standing in the middle of a circular slate, and the time mark is engraved around the slate. As the sun rises and sets, the shadow of the iron needle can indicate the time. In the Yuan Dynasty, Guo Shoujing set up a stargazing platform in Dengfeng, Henan Province, which was 40 feet high, 128 feet long and weighed 18 tons, making the reading of the length of the sun shadow accurate to 0. 1 mm. The Forbidden City in Beijing still retains the excellent cultural heritage of ancient sundials.

/kloc-In the middle of the 6th century, Italian physicist Galileo was inspired by the chandelier in the church and invented the pendulum clock, which was born. However, the clock at that time was extremely simple, with only one hour hand indicating "time". The minute hand only appeared in the 18th century, and the second hand only appeared in the 19th century. People divide a day into 24 hours, 1 hour 60 minutes and 1 minute 60 seconds. One second is 1/86400 of an average solar day.

With the development of science and technology, the watch industry is also developing rapidly. From mechanical pendulum clocks to electronic watches, there are all kinds of clocks and watches. These clocks are enough for us to keep time every day.

But the earth's rotation is not exactly 24 hours a day, and there will be a difference of one second around 10 years. For example, 1992 will be wetted for one second. Therefore, a more accurate timing standard is imperative. 1967 the new time standard was adopted in the13rd international power conference:

1 sec = the time for cesium atom to vibrate 9 19263 1770 times.

This cesium atomic clock has been used for 300 thousand years, and the error is only one second! The running second of 1992 is determined by this cesium atomic clock. At present, scientists are exploring a higher standard time service system. Theoretically, it is predicted that the accuracy of the time standard established by laser can be improved by 10,000 times!