Nilometers, as the name literally suggests, were used to measure the level of the river Nile in Egypt. Nilometers were large structures built by ancient Egyptians along the Nile river to measure impending water rise during annual floods. The Nilometers were calibrated with markings in cubits (1 cubit is approximately 50 cms) to interpret the water level.
16 cubits meant the right amount for an abundant harvest, while too low or too high levels meant devastation due to famine and over flooding respectively.
The conical ceiling of the Nilometer at Rhoda Island near Cairo, Egypt |