Before Batteries: The Forgotten Engineering of Ancient Sand Clocks ⏳ #AncientEngineering#STEMUSA#usa

Hinzugefügt: 2026-05-25

[00:00:00]If you take a wooden beam from your house and stand it on a high platform, you can tell the time by the beam's shadow. But once it gets dark, you can no longer get an accurate read. Being clever, you realize you can mark measurements inside a funnel and measure time by the flow of fine sand. However, keeping time this way is still very inconvenient. How can we make [music] time more precise? Being clever, you realize you can install a wooden wheel under the sand glass. When the flowing sand drives the wooden wheel to complete one full rotation, that equals 10 minutes. But there are 1,440 minutes in a day and counting every 10 minutes [music] is too tedious. So you attach a 10-tooth gear to the wooden wheel and bring in five sets of gears with different numbers of teeth to [music] interlock with it. This way, through the step-by-step deceleration of the five gear stages, you successfully [music] reduce the rotation speed to a 1:144 ratio. This means that for the final gear to complete one rotation, the flowing sand needs [music] to drive the wooden wheel to rotate 144 times. And 144 [music] rotations exactly equal 1,440 minutes, which is 24 hours. This way, you only need to attach a pointer to the final gear and pair it with a dial marked with the 12 traditional hours, shichen. You can then get the accurate time day or night based on the pointer's position. Well, congratulations. You've successfully invented the ancient [music] timekeeping device.