Water Clock

A water clock, or clepsydra, is a timepiece that measures time by the regulated flow of liquid into or out of a vessel, among the oldest time-measuring instruments known. Simple forms existed in several ancient civilizations, including Babylon, Egypt and Persia, by around the 16th century BC. The oldest surviving physical example dates to about 1417 to 1379 BC in the New Kingdom of Egypt, during the reign of Amenhotep III, and the oldest documented attribution is a tomb inscription of the 16th-century BC Egyptian court official Amenemhet, which names him as its inventor.