everyday lifetimekeepingmeasurement
Hourglass
A device used to measure the passage of time, consisting of two glass bulbs connected vertically by a narrow neck that allows sand to flow from the upper bulb to the lower one at a constant rate.
A device used to measure the passage of time, consisting of two glass bulbs connected vertically by a narrow neck that allows sand to flow from the upper bulb to the lower one at a constant rate.