A nilometer was a structure for measuring the Nile River's clarity and water level during the annual flood season. There were three main types of nilometers, calibrated in Egyptian cubits: (1) a vertical column, (2) a corridor stairway of steps leading down to the Nile, or (3) a deep well with culvert. If the water level was low, the fertility of the floodplain would suffer. If it was too high, the flooding would be destructive. There was a specific mark that indicated how high the flood should be if the fields were to get good soil.
Measuring shaft of the nilometer on Roda Island, Cairo
Nilometer shown c.1800 at the southern tip of Roda Island
Palermo Stone, 5th Dynasty (2392 B.C.E-2283 B.C.E)
Conical structure covers the nilometer on southern tip of Roda Island in the Nile River at Cairo. The structure is modern but the nilometer dates from 715 AD.
The flooding of the Nile has been an important natural cycle in Nubia and Egypt since ancient times. It is celebrated by Egyptians as an annual holiday for two weeks starting August 15, known as Wafaa El-Nil. It is also celebrated in the Coptic Church by ceremonially throwing a martyr's relic into the river, hence the name, The Martyr's Finger. The flooding of the Nile was poetically described in myth as Isis's tears of sorrow for Osiris when killed by his brother Set.
The festival of the Nile as depicted in Norden's Voyage d'Egypte et de Nubie
View in the Delta during the inundation of the Nile, 1847
