In ancient times, there were no tools such as clocks and watches that could tell time at any time. During the day, you can calculate the time by the sun or the sundial. At night, there is no light, and all these things are useless, but everyone still needs to know what time it is. At this time, people can generally rely on external objects, such as burning incense or hourglass, or some more powerful people can know the time by looking at the stars. But the hourglass is not something that ordinary people can afford, and the way to see the stars is not something that ordinary people can master. Therefore, in order to let the people know the time at night, the occupation of playing overtime came into being.

In ancient times, there were few recreational activities, and most people went to bed as soon as it got dark. However, some people need to do activities in the evening or early morning, so they can only know the time by listening to the beat. Although this method is a bit inaccurate and inaccurate, it is better than nothing.

People who work overtime are generally called night watchman. They all have their own unique equipment. They go to work at night all year round in monsoon rains, rain or shine. When they go to work, it's not just like a TV series. They just shouted that the sky was dry and things were dry. Be careful of the fire. If this is the only slogan, how do people know what time it is? It is impossible to stay up all night. Count how many slogans they said. So they actually have many different slogans to correspond to different times besides this sentence. For example, from 7: 00 pm to 9: 00 pm, dry and dry, and be careful with candles. 9: 00 to 1 1: 00 will become closed doors and windows to prevent theft, so listen to different slogans to know what time it is at night.