We know that the column of the Nilometer has been frequently repaired, which fact explains the apparent discrepancy between the height of the gauge as given in Benjamin's narrative and the figures just mentioned.
"The Itinerary of Benjamin of Tudela"
Benjamin of Tudela
Old Cairo is a village some three miles from the city, higher up the river; and here, close to the Nilometer, by which the golden increase of the river is measured, tourists going to the Pyramids are ferried over the river.
"The Bertrams"
Anthony Trollope
In order better to understand the rise of the Nile, to fix the amount of the land-tax, and more fairly to regulate the overflow through the canals, the Nilometer on the Island of Elephantine was at this time made.
"History Of Egypt From 330 B.C. To The Present Time, Volume 11 (of 12)"
S. Rappoport