We live in a world where time is all important. Nanoseconds mark the difference between success or failure to make an electronic transaction and where we are continuously reminded of “the time”: of being early or late, of having missed an appointment or arriving “before time”. In today’s world, time now governs our life.
The Ancient Egyptians used simple sundials and divided days into smaller parts, and it has been suggested that as early as 1,500BC, they divided the interval between sunrise and sunset into 12 parts.
Our familiar divisions of time are more recent and current terminology about time and time-keeping originated from the Babylonians and the Jews.
The sundial was refined by the Greeks and taken further by the Romans a few centuries later. The Romans also used water clocks which they calibrated from a sundial and so they could measure time even when the sun was not shining, at night or on foggy days. Known as a clepsydra, it uses a flow of water to measure time. Typically a container is filled with water, and the water is drained slowly and evenly out of the container – markings are used to show the passage of time.
But the changing length of the day with the seasons in the Roman world made time measurement much more fluid than today: hours were originally calculated for daytime and based on a division of the day. The water clock made it possible to measure time in a simple and reasonably reliable way.
In the 18th century the clock emerged as a scientific instrument in its own right, notwithstanding its conventional role to mark the passing of the hours.
A pendulum clock is a clock that uses a pendulum, a swinging weight, as its timekeeping element. It was invented in 1656 by Christiaan Huygens. From the year 1656 until the 1930s, the pendulum clock was the world's most accurate way of keeping time.
The pendulum clock owes is refinement to Galileo noticing the regularity of a suspended lamp swinging back and forth in the cathedral of Pisa, when he was still a student there.