The nilometer, or "mikyās," on the island of Rôda, now visible, is stated to have replaced one which was brought thither from Memphis at some unrecorded date. Makrīzī in 1417, according to Ebers, saw the remains of the older nilometer.
SCALE OF THE NILOMETER AT RÔDA.
The present mikyās is within a covered vault or chamber, the roof being supported on simple wooden pillars. In a quadrangular tank in communication with the river by a canal is an octagon pillar on which the Arabic measurements are inscribed. These consist of the pic (variously called ell or cubit) = 0·54 metre, which is divided into twenty-four kirats. In consequence of the rise of the river bed in relatively recent times, the nilometer is submerged at high Nile to a depth of two cubits.
The rise of the Nile can now be carefully studied, as gauges are distributed along the river. We have the Aswân gauge from 1869, the Armant gauge from 1887, the Suhag gauge from 1889, and the Asyût gauge from 1892. The distances of these gauges from Aswân are as follows:—
| Kilometres. | |
|---|---|
| Aswân | 0 |
| Armant | 200 |
| Suhag | 447 |
| Asyût | 550 |
| Rôda | 941 |
The Rôda gauge is not to be depended on, as the movements of the barrage regulation destroy its value as a record. The heights of these gauges above mean sea-level are as follows:—
| Metres. | |
|---|---|
| Aswân | 84·158 |
| Armant | 69·535 |
| Suhag | 56·00 |
| Asyût | 53·10 |
| Rôda | 13·14 |
THE ISLAND OF RÔDA.