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Nilometer, Rhoda Island
A Nilometer is an ancient instrument used to measure the level of the Nile river and predict its behaviour. Several existed in ancient times, with one still surviving on Cairo’s Rhoda Island. This Nilometer is essentially a marble column surrounded by stairs, from which priests would take readings of the water levels. While Nilometers existed some 5,000 years ago, this particular model was built in 861 AD, replacing an older model on the same site.
