The Earliest Hourglass Sand Clock
Jul 12, 2022
The Chinese hourglass is an ancient instrument for measuring time. Timing sand clock hourglass is made in much the same way as a clepsydra, measuring the time it takes for quicksand to pass from one container to another.
In China, there were sundials and clepsydra, but sundials could only be used in the daytime and sunny days. The reason for using quicksand instead of water is that the air in northern China is cold in winter and water is easy to freeze.
The most unique sand clock hour glass is the "five-wheeled hourglass" created by Zhan Xiyuan in 1360. Quicksand flows from the funnel-shaped sand pool to the sand bucket on the edge of the primary wheel, driving the primary wheel, which drives the rotation of mechanical gears at all levels. The last gear turns the middle wheel, which rotates horizontally, on an axis with a pointer that turns around a notched instrument disk to show the time. This method is almost identical to the surface structure of modern clocks.
In addition, Zhan cleverly added a mechanical toggling device to the middle wheel to alert the two wooden figures standing on the five-wheel hourglass to beat a drum to tell the time. Every hour or a moment, two wooden people will come out, beat the drum to report the time. The hourglass has become a mechanical clock structure without the help of astronomical instruments. This sand watch timer is more accurate than a clepsydra due to the lack of water pressure.
