The Development of the Hourglass Timer
Jul 12, 2022
The earliest timekeeping devices were used to judge time by the length and direction of the sun's projection, but such real-time devices were limited, so the hourglass was invented. If used in the cold season, water would easily freeze, so it was driven by sand. The famous old sand clock with five wheels was created by Zhan Xiyuan in the early Ming Dynasty. The sand watch calculates and measures t...