It is believed that the Babylonians fist used a pole fixed in the ground to measure the passing of time. They noticed that the position of the shadow changed during the hours of sunlight. They found that the shadow was long at sunrise and that it slowly grew shorter until it reached a point when it started to lengthen again. They learnt to judge the time by looking at the shadow.
The simple shadow and pole arrangements were the basis of the various shadow clocks or sundials used by the ancient Egyptians. Eventually sundials were provided with the hour figures engraved on a metal plate.
The Egyptians also used a clepsydra or water clock. This was a basin-shaped, alabaster vessel filled with water that ran out through a hole in the bottom. The time was indicated by the level of water remaining inside.
Monks were the first to operate clocks by wheels and weights. Clocks of this type, found in monasteries, date back to the 14th Century. The first spring clock is dated about 1500.
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