We now come to the third, which is the historical, stage. By a series of enormous dykes, some of them several miles in length, the enclosed space having a breadth also of some miles, the inflowing water was confined to certain portions of the upper plateau; perhaps the whole of the upper plateau was by these means formed into a lake. The water thus retained and secured, was amply sufficient for the perennial irrigation of the whole of the descent reaching from the upper southern plateau down to the Birket el Keiroon, and for a district to the west and south, and, when the effects of the inundation began to be exhausted in the valley of Egypt, for the contiguous departments of Memphis and Heracleopolis. In this way the creation of the Faioum, the most fertile province in Egypt, was far from being the whole of the benefit derived from these vast waterworks. The lake, or series of connected lakes, formed on the summit of the plateau may have been twenty miles long, and two or three wide. This was the famous Lake Mœris. The water was made to enter the lake by a channel, which probably commenced at the modern Howarah, and was drawn off for irrigation outside the Faioum by a channel which appears to have passed out at Illahoun. In each of these a sluice was constructed. The extreme costliness of opening and shutting these sluices shows that they must have been enormous structures: but this was only in proportion to the vast volume of water that passed through them. To fill such lakes during the time of the high water of the inundation nothing less than a considerable river would have sufficed. We can only think it very much to the credit of these primæval engineers that they managed such sluices at all. Nothing like either the slatts, or the locks, on some of our rivers for holding back the water, would have answered their purpose. They wisely made the channel for letting out the water quite distinct from that for letting it in; for, if one of the sluices got out of order, then the other might be used while the damages of the injured one were being repaired. In a matter of life and death to so many it would not have done at all to have had only one string to their bow.