Measuring a River:
The Nilometer on Rawda

July 26, 2006

Egypt is dependent on the Nile to an extent that is difficult to communicate. I have been in Cairo for close to three months, and I have not felt a single drop of rain. The closest I come to the experience of rain is when walking underneath someone's drippy A/C. The empty deserts on either side of the Nile valley offer a portrait of Egypt without the Nile. Throughout Egypt's history.. at least until the construction of the High Dam in Aswan, which regularized this natural process.. the year revolved around the annual Nile inundation, which crested in September. A low inundation.. or too high of an inundation.. meant failure of crops. The tax rates were historically aligned with the inundation level: low water level = low taxes. This economic management of the Nile and the Egyptian economy made necessary the use of some kind of measuring system, and thus the importance of the Nilometer on the island of Rawda.

Egyptians knew that the Nile had been measured far back into their history. Al-Maqrizi cites Ibn 'Abd al-Hakam, the earliest historian of Egypt whose work survived to our own time:

The first person who measured the Nile in Egypt was Joseph, upon him peace, who founded a gauge at Memphis. Then the old woman Daluka, daughter of Zabawahi, originator of the "Wall of the Old Woman", founded a gauge at Esna (although it was small of measure) and one also at Akhmim. 'Abd al-Aziz ibn Marwan founded a gauge at Helwan (although small). Usama ibn Zayd al-Tunukhi also set up a gauge on the island, which was the largest of the gauges. [1:57]

The original measurement is thus traced back to a biblical prophet: Joseph. But finally we reach the gauge built by Tanukhi, which was constructed on the island.. which here means Rawda. William Popper in his study on the Nilometer identifies this as taking place in 715 AD. Popper also clarifies that what we now know as the Nilometer is largely the result of the construction ordered by the Caliph Mutawakkil around 860 AD.

The Andalusian traveler Ibn Jubayr gives a description of the Nilometer from the year 1183 AD:

Beside this mosque is the Nilometer, which measures the Nile's increase at the time of its yearly flooding. The beginning is expected in the month of June, the maximum in August, and the ending in the beginning of October. This measuring instrument is a is a white octagonal column of marble set in a place which confines the water as it flows into it. It is divided into twenty-two cubits, subdivided into twenty-four parts called 'fingers'. [Broadhurst translation, 47]

This can be better understood with a look at a picture:

You can see how the pole itself is divided into cubits, which in turn are divided into 24 spans (count them!). Within the arch is an inlet so that the water running outside can flow into the well and therefore be weasured. Three such inlets are present along the vertical wall of the well.

While everything about the well itself appears to be quite old.. the structure that lies over the well is much more recent.. Ottoman or later. From the outside you see an unusual pointed dome.. to my eyes reminiscent of the top of a pointed Ottoman minaret:

Looking out from the other side of this structure, you find the broad expanse of the Nile. To the right is Giza, and straight ahead is yet another island.. this reachable only by boat and devoted largely to agriculture:

Looking at that other island I have wondered if the island of Rawda once looked just like that.. a couple places of development, but mostly green with agriculture. When I looked through the French illustrations to the Description de l'Egypte I found a drawing of Rawda:

What a romantic island.. ruins, pastoral fields, and the pyramids in the distance. That was 200 years ago. Along the island of Rawda you will find no scene like this. For the most part Rawda looks just like the rest of Cairo: