Dating an accutron watch
Other regions of the world, including India and China, also have early evidence of water clocks, but the earliest dates are less certain.
Some authors, however, write about water clocks appearing as early as 4000 BC in these regions of the world.
Devices operating on several physical processes have been used over the millennia.
A sundial shows the time by displaying the position of a shadow on a flat surface.
In the hourglass, fine sand pouring through a tiny hole at a constant rate indicates an arbitrary, predetermined, passage of time, the resource is not consumed but re-used.
The timekeeping element in every modern clock is a harmonic oscillator, a physical object (resonator) that vibrates or oscillates repetitively at a precisely constant frequency.Instead, water clocks in ancient societies were used mainly for astrological reasons.These early water clocks were calibrated with a sundial.The Greek and Roman civilizations are credited for initially advancing water clock design to include complex gearing, which was connected to fanciful automata and also resulted in improved accuracy.These advances were passed on through Byzantium and Islamic times, eventually making their way back to Europe.