All Kinds of Clocks
In everyday life, we are probably most familiar with time from two sources: clocks, and our inner psychological experience of time.
Clocks are everywhere. There are grandfather clocks, watches, alarm clocks, even incense clocks that let you tell the time through scent.
There are also natural clocks.
But clocks existed well before the modern invention of portable artificial ones. Over four thousand years ago, the Egyptians used obelisk shadow clocks, sundials, and water clocks which measured time by the flow of water passing through a stone vessel. 4