eastward in the mornings. At noon, the device was turned around so that it could cast its shadow in the evening direction.

Alarm clocks reportedly first appeared in ancient Greece with a water clock made by Plato that would set off a whistle. The hydraulic alarm worked by gradually filling a series of vessels with water. After some time, the water emptied out of a siphon. Inventor Ctesibius revised Plato's design; the water clock uses a