construction of the dams. The statement of the priests about the height of the inundation in the reign of Moeris, which Herodotus has preserved for us, and from which he has drawn the conclusion that the soil of Lower Egypt must have risen since that reign from seven to eight cubits in height, is much exaggerated. The deposit of mud in consequence of the inundation raises the soil only about four inches in 100 years, that is, about three-and-a-quarter feet in 1,000 years. Supposing the basin of Amenemha to have been completed 1,500 years before Herodotus travelled in Egypt, the difference in the required height of the inundation might reach three or four cubits, but not seven or eight. Yet the raising of the soil, and more especially of the bed of the great basin, which rose far more rapidly than the surface of the land, brought about the decay, and at last the ruin, of this reservoir. The bed of the basin in which the water remained the whole year through, and not for three or four months only, must have been raised by the deposit at a peculiarly rapid rate; at the present time it shows a height of eleven feet as compared with the land outside the remains of the dams.[169] With this rise in the bed, the value of the basin diminished in proportion as the amount of water which the reservoir was capable of receiving was lessened. It was useless to raise the height of the dams, for the influx of the water from the Nile depended on the level of the bed of the connecting canal, and of the basin. These causes along with the disaffection of later times must have brought about the decay of the reservoir, the value of which Diodorus places so high, and which was in existence in the time of Tacitus. At a later period the dams must have been neglected, so that at the time of some extraordinary inundation, a breach was made towards the west, which filled the western and lowest part of Fayum with water. This is the origin of the Birket-el-Kerun, the water of which is still sufficient to convert the largest part of Fayum into one of the most fertile and blooming districts of Egypt. The level of the Birket-el-Kerun is seventy feet lower than the canal which once connected the reservoir with the Nile.[170]