What is a sundial?

Many friends don't know the sundial. Its invention has been used by human beings for thousands of years. Today, let's take a look at what a sundial means to solve your doubts.

1, sundial is an ancient time-measuring instrument.

2. In ancient times. At first, people used their eyes to observe the changes in the height of the sun to determine the time. There is no sun at night, and you can also observe the heights of the moon and stars to determine the local time. This method is called visual inspection. Later, it was found that it was more accurate to judge the time according to the shadow length of the object cast by the sun on the ground: erect a wooden pole in the open space and observe the change of the shadow length. The shadow of the pole is getting shorter and shorter in the morning, shortest at noon and gradually longer in the afternoon. This method is called Guice method. According to this principle, various sundials were made.

3. 7th century BC. China invented Tugui, and he measured the shadow with a vertical rod. The Greeks also made different sundials. Without the sun, the sundial can't be used. People invented the clepsydra (water clock) and the sand clock, and until now, the mechanical clock and the electronic watch.

The above is an introduction to what a sundial is.