This will also account for something more, that is, for the disuse and obliteration of the lake. The mud had at last taken the place of the water. The dykes had not been made of any great height at first, but, as the soil rose both within and on the outside, they had, in the course of two thousand years, been frequently raised correspondingly. Of course, the bed of the Nile, like that of the Po, gradually rises, but the amount of this rise is not great, and would bear but a small proportion to the rise of the bottom of the lake. Lake Mœris, therefore, contained in itself, as so many natural lakes have done, a suicidal element. What made it a lake was destined to make it one day, what it has long been, dry land. This was, from the first, only a question of time. Water could, of course, again at this day be dammed up upon the site of the old lake, but only by taking it from the river at a higher point than of old; higher, that is to say, than the inlet of the Bahr Jusuf Canal at the old Diospolis Parva; for instance, it might be necessary to take it now from above the Cataract of Philæ, though, indeed, if that could be engineered, we cannot suppose that it would pay, for the Faioum, including the bed of the old lake, is pretty well irrigated now, though, of course, it has no storage of water for the needs of the adjacent river-side lands. It is obvious that we must connect with these vast and scientifically-carried-out hydraulic works of the Faioum, the registration of the height of the annual inundation Herodotus mentions, and of which we have still existing evidence in the rock-cut records at Semnéh, we referred to in our first chapter. He says this registration was commenced in the time of Mœris. Now Mœris was that Amenemha III., who constructed these great reservoirs of the Faioum, and after whom they were ever afterwards called. The connexion between the yearly marking of the height of the rising at Semnéh, in Nubia, and the reservoirs of the Faioum might have been that the register at Semnéh was a detective apparatus for showing how much water ought each year to have been brought into the reservoirs; it would also indicate what was the need for irrigation in the contiguous departments outside the Faioum; and thus be a guide for the regulation of the amount of water that ought to be let out each year. In the waterworks of the Faioum there was a grand utility with which our thought is more than satisfied: in the Labyrinth was seen the architectural glory of the newly-created province; it was the greatest construction of the old Monarchy: the Pyramids had been a rude introduction to it; and it suggested to the younger monarchy the chief structures of Karnak. If we could now behold it, as it stood at the time when the Hyksos broke into Egypt to become its masters for between four and five centuries, we should regard it as one of the most historically interesting and instructive buildings ever erected in the world.