Knowra Water clock Water clock A timekeeping device that measures elapsed time through the regulated flow of water into or out of a vessel. Its accuracy depends on controlling how flow changes as water levels shift.
Clepsydra : An ancient water clock that measures time by the movement or level of water. The Greek name is commonly used for ancient inflow and outflow designs.
Ancient Egyptian timekeeping : The systems ancient Egyptians used to measure and organize time, including calendars, sundials, and water clocks. Egyptian outflow clocks are among the earliest known water-clock designs.
Athenian law courts : The civic courts of ancient Athens, where citizens tried cases under democratic legal procedures. Water clocks allotted limited speaking time to litigants and their representatives.
Sundial : A device that indicates time from the Sun’s apparent position by casting a shadow. Unlike water clocks, sundials require sunlight and indicate local solar time.
Escapement : A mechanism that controls the release of energy in a clock, advancing its timekeeping element at regular intervals. Mechanical clock escapements addressed the need for more regular timing than changing water flow could provide.
Hydrostatic pressure : The pressure exerted by a fluid at rest, increasing with depth below its surface. Changing water depth changes pressure and therefore the discharge rate from an outlet.
Karnak clepsydra : An ancient Egyptian outflow water clock found at Karnak and dated to the reign of Amenhotep III. Its vessel markings show how one early design accounted for seasonal changes in daylight.
Astronomical clock : A clock that displays astronomical information such as the positions of celestial bodies or calendar cycles. Water-powered mechanisms could coordinate timekeeping with moving astronomical displays.
Hourglass : A time-measuring device that tracks material passing through a narrow opening between chambers. Sand clocks measure a fixed interval through falling grains rather than water flow.
Hydraulic engineering : The engineering of systems that control, convey, and use water. Building reliable water clocks drew on precise control of reservoirs, channels, and outlets.
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