“Let’s Make a Water Clock,” Friend, Jan. 1975, 26
Let’s Make a Water Clock
Did you know that you can tell time with a water clock?
All you’ll need is an empty milk carton, a two-or three-quart-size shallow pan, and food coloring.
Punch a small hole in the side of the carton near the bottom and fill the carton with colored water. Then place the water-filled carton inside the pan. The water will drip slowly out of the carton and into the pan.
To start the water clock, hold the carton up to the light or use a flashlight and mark the level of the colored water inside when it’s full. Then mark the level after every fifteen minutes.
Refill the carton with the colored water and you are ready to tell the time accurately with your water clock.