At a sundial the time is indicated by a rod or a protruding stone that throws a shadow on a dial.
The first known sundials were used in China at about 2679 BC.
Approx. 1800 BC on public squares and in front of temples large sun pillars (obelisks) were erected, whose shadow indicated the hours on colored plates. Around 1100 BC also Chou Kong, Emperor of China, used to measure time with such a device when the sun shined.
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