It is, I think, evident that, when Lake Mœris ceased to be, Hawârat-el-Maqta was the key to the position and the point where the problem of the Fayûm irrigation had to be solved. It was necessary for the irrigation of the whole province, that the water-level should be held up at this point, so as to flow along the ridge between Hawârat-el-Maqta and Medineh, from which the whole province, with the exception of the land on the right of the north drainage line, was commanded. For the irrigation from the Bahr Sêlah or from the ancient canals, of which the Bahr Sêlah is the modern representative, it was necessary also that the water should not be allowed to run to low levels down the ravine at the back of Hawârat-el-Maqta. The principal operation then to be performed was to bar this ravine to the passage of the water, and to make the water flow forward along the ridge to Medineh at a high enough level at least to pass over the rocky bed, which is now found in the modern Bahr Yûsuf about a kilometre beyond Hawârah. This end being attained, the water would flow along the ridge, from the sides and end of which it would be distributed into the different branch canals covering the face of the province. Works to control the quantity of water given to each branch, and weirs to head-up the water at intervals along the canals of too rapid a slope would have been added as the want of them made itself felt. The lake level would become lower year by year, and more land would be reclaimed and brought under cultivation. At some period of this process, probably after a breach at Hawârat-el-Maqta, or on the failure of the regulator supposed to have formerly existed at Hawârah, the Lahûn bank and its old regulator would have been formed to exclude the excess of water and to control the discharge admitted into the Fayûm. (For sections of these banks, see Plate XXVII.) I have suggested before that the part of the Lahûn bank which runs east and west was made in the time of Lake Mœris, and that the part from Lahûn to the south side of the gap, which crosses the Bahr Yûsuf at the old Lahûn Bridge, was subsequently made to shut out the Nile floods, when for some reason the means of regulation within the Fayûm at Hawârah ceased to be efficient. The old Lahûn Bridge has three openings of 2·67 width, the floor level of two of them being at R.L. 21·97 and of the third at R.L. 20·72, so that this bridge could only have been constructed _after_ the discharge required by the Fayûm had fallen to the amount of its present requirements, or to even less, as the waterway is somewhat under what is desirable for the passage of 7 million cubic metres a day, the maximum discharge utilised in the Fayûm at the present day during floods. [Illustration: PLATE XXVII. BANK RIGHT OF LAHÛN BRIDGE, OR GISR GADALLAH.] [Illustration: BANK LEFT OF LAHÛN BRIDGE, OR GISR BAHLAWÂN. CROSS SECTIONS OF LAHÛN BANKS.]