“So many opinions have been broached about Lake Moiris that an account of antiquities in the Fayûm without mentioning it would seem impossible. So, although my work has not been in that line, yet it will be well to state what seems to be the truth about it, in order that some collateral questions should be the better understood. For the following view of the use of the great dyke I am indebted to Colonel Ross, R.E., C.M.G., who has professionally considered the subject. The Fayûm is one of the oases of the Libyan Desert, lying close to the Nile Valley; and the intervening ground is low enough for the Nile to pour into the basin. The fall from the Nile Valley to where the channel widens out into the Fayûm is about 12 feet; and the water flows over the province by canals and ravines, worn through the rock and its superincumbent mud, until the streams finally collect in the Birket Kurûn at more than 200 feet below the Nile level, and, indeed, 130 feet below the sea. The present area of cultivation is about 20 miles in each direction; but the whole basin, geographically speaking, is about 40 miles across on an average. This does not include the secondary basin of the Wadi Raian to the south, which never had any connection with the Fayûm basin in historic times, the ground rising over 100 feet above Nile level between the two depressions. “In pre-historic times the Nile Valley was full of water to a far greater depth than at present, probably 100 to 200 feet deep of water filled it right across. A river of such a size seems almost incredible, and we naturally should suppose it to have been an estuary; but this must not be too hastily assumed, as there are evidences over the whole country of an enormous rainfall, which ploughed up the cliffs with great ravines; while the bare bed of the old Nile in the eastern desert at Silsileh is some miles in width, showing what a large volume of water has filled it; a lesser stream would have cut down a deep channel in the old bed, and would never have filled that and topped the rocks to force its present cut. This pre-historic high Nile is not, however, pre-human, as I found a palæolithic flint high up on the hills to the west of Esneh, clearly river-worn. The geologic conditions, then, in the pre-historic time prove that the Fayûm Basin must have been a vast lake, connected by a broad arm with the Nile Valley. Thick beds of Nile mud exist beneath 10 to 20 feet of deposits washed down from the desert hills; and even this desert detritus is strewn with felspar and quartz pebbles brought in by the Nile from Assuan, and now lying high above the present Nile level. As the rainfall ceased, and the Nile fell, the neck of water was reduced, but it still sufficed as a channel for the filling of the Fayûm, in all probability, in the time of the earliest dynasties. The Nile bed has risen, it is true, 4 inches a century by its deposits; and hence at the time of the XIIth