If we suppose this water husbanded and made use of only during the 100 days of summer, when its want is most felt, the lake would give an average daily discharge to the Nile of 31½ million cubic metres, that is, the low Nile discharges would be doubled and raised from 30 millions to 60 millions. But by a careful distribution of this stored-up water between the months of April, May, and June, and ten days of July, it would have been possible to keep up the discharges constantly to seventy millions, as shown in the table below:— --+-----------+-------------------+-------------+----------------+-- | | Average Nile | Supplied by |Total Increased | | Month. |Discharge, without | reservoir. | Discharge. | | | reservoir. | | | +-----------+-------------------+-------------+----------------+ |March | 70,000,000 | Nil | 70,000,000 | | | | | | |April | 45,000,000 | 25,000,000 | 70,000,000 | | | | | | |May | 34,000,000 | 36,000,000 | 70,000,000 | | | | | | |June | 34,000,000 | 36,000,000 | 70,000,000 | | | | | | |July 1 to 8| 45,000,000 | 25,000,000 | 70,000,000 | --+-----------+-------------------+-------------+----------------+-- The supply from the reservoir will thus be (36 million × 61 days) + (25 million × 38 days) = 3146 million cubic metres. Such an increase of the summer supply would probably have the effect of doubling the area under summer crops in the Delta, if it could be obtained now, but it is not clear how it could have been utilised without a barrage to raise the water-level, and without, as far as we know, any Sêfi (summer) canals. It is not, however, imagined that in the days of Lake Mœris there was any such scientifically economical control of the Nile waters, as supposed in the foregoing calculations, but they are given to show what the _possibilities_ of a lake under the conditions assumed would be. My aim has been to establish its utility, in answer to Linant’s argument against the developed Lake Qurûn theory, which consisted in a demonstration that this lake could have served no useful purpose, such as the historians credited it with. Possibly the needs of navigation were a more important consideration in those days than summer irrigation, though not given the first place now. An increased volume supplied at low water to the shallowing water-routes would even for this object have been a gain.