when was the nilometer invented?
Stone steps uncovered at the ancient port city of Thmuis are part of a nilometer, a structure used in antiquity to monitor the level of the Nile River. American and Egyptian archaeologists have discovered a rare structure called a nilometer in the ruins of the ancient city of Thmuis in Egyptâs Delta region. Likely constructed during the third century B.C., the nilometer was used for roughly a thousand years to calculate the water level of the river during the annual flooding of the Nile. Fewer than two dozen of the devices are known to exist.