The flood of 1874 was an early one and the basins were discharged on a falling Nile, still they raised the Cairo gauge to 8·7 metres on the 5th October while it would have risen to 8·5 on the 15th September with perennial irrigation. The flood of 1878 was an exceedingly late one and the basins had to be discharged while the river was still very high. By the 10th October, the river had risen to 8·7 metres at Cairo when the banks were breached and all future rise stopped. With perennial irrigation, the maximum gauge of 8·6 metres would have been reached on the 10th October. The flood of 1892 was at Assuân 10 centimetres below that of 1874 and 20 centimetres below that of 1878, and midway between them in point of time. It was also under complete control owing to the new regulating works on the basins. It rose to 8·4 metres at Cairo on the 5th October and fell exceedingly slowly. With perennial irrigation, it would have risen to 8·4 at Cairo on the 30th September and then fallen rapidly. Speaking generally, we may say that with perennial irrigation the very high floods at Cairo will be 15 days in advance of what they are at present, that they will not rise higher, and that they will fall 15 days earlier than what they do now. With low floods there will be no appreciable difference as to date, but the floods will be slightly higher at Cairo. In ordinary floods, there will be an advance of from 20 to 25 days in the date of the maximum flood, and a maximum gauge at Cairo 50 or 60 centimetres under the maximum gauge at Assuân. We have so far considered Cairo only, as the Delta proper depends on the Cairo gauge. We now turn to the Nile in Upper Egypt itself: south of Sohag, there will be no serious change in levels, but the Sohagia and Ibrahimia canals between them carry at present 750 cubic metres per second in excess of what they would carry if there were perennial irrigation in Egypt, and the greater part of this water is not returned to the Nile until the Kushesha escape is reached. The reach of the Nile from Sohag to Kushesha is the one which will experience the greatest changes, and I calculate that there will be a rise of 40 centimetres as compared with the maximum gauges under basin irrigation.