All of these items have been used to measure time. Medieval kings used candles as clocks. Hourglasses use sand to drip through the glass bulb over a set duration.My picture is of our night light clock. It tells us the time digitally. Like the other 2 things it also measures time using a set calculation. There are 12 stars on the clock that disappear after a set number of minutes depending on long you set your sleep time for. When it is time to wake up the stars have disappeared the same way that the candle wax would melt away or the sand moves away.
