The history of timekeeping is the story of the search for ever more consistent actions to regulate the rate of a clock, which needs a repetitive process to mark off equal increments of time. Early examples of such processes included movement of the sun across the sky, candles marked in increments, oil lamps with marked reservoirs, and sand glasses.

The first water clocks were simple containers designed to slowly fill with water coming in at a nearly constant rate. The water level reaching markings on the inside surfaces allows for measuring the passage of time.

On the other hand, the decay of radioactive elements is a random, rather than a repetitive process, but the statistical reliability of the disappearance of any given fraction of a particular element can be used for estimating longer time intervals.

Accuracy in timekeeping has improved steadily since the first mechanical clocks. Early ones, like the Dover Castle, were regulated by weighted bar called the foliot, which pivoted back and forth to move a single hand. But foliot mechanism still varied by several minutes a day until the pendulum clocks came into general use.

George Graham was the first to compensate for the fact that temperature changes cause steel pendulums to vary in speed. His clock had a temperature-independent mercury-vial pendulum, which varied only by one second a day. Accuracy continued to improve as pendulums were superseded by quartz crystals that vibrated so precisely that they made possible a clock accurate to a few thousandths of a second a day.

Atomic clocks paced by vibrating cesium atoms were perfected until they were precise to about one second every 350,000 years. The best accuracy *of all time* has been achieved by the JILA's strontium clock which would neither gain nor lose a second in more than 200 million years."

________________________

The science (logos) of time (chronos) is represented on the table as a chronology starting with a sundial's arrow pointing to the word "DATE", and leading to the modern digital display. In the mid-19th century (lower-right of the evolution print), Foucault presented his famous pendulum, which is not a clock because it has a regular tempo. It indicates time progression because the stationary base moves, while rotating around Earth's axis every 24 hours. It appears as though the pendulum changes direction, but this is an illusion.

On the other side of the table, the Newton's cradle stands for the free-swinging pendulum era, the masonic triangular pendulum (on the floor), the Cuckoo's (and/or Grandfather's) pendulum, and of course the 5 clocks of the chronology.

Finally, a spiritual triangle connects the chair, the cradle, and the light source. The chair is used for meditation. One has to drink a glass of water before any ritual to symbolize inner purification.

Please sit down, take the time to feel the time one more time. Ponder over the triangular pendulum, the one which is below and the one which is above, and keep on listening to the ticking sound of time flow