— 93 — 
not any inherent viciousness in the Albert Nile itself. The Albert 
Nile has a good section, and, if it were trained in conjunction with 
the Zeraf river, would, I feel confident, discharge all the water required 
with a very moderate expenditure of money. This, I always understood, 
was Sir William’s own opinion. In such projects it is wise to remem- 
ber Horace’s saying, “ Naturam furca expellas tamenusque recurrit. ” 
38. Project for converting the basin irrigated lands of 
Upper Egypt into perennially irrigated lands.- — No conside- 
ration of this question would be complete without first examining into 
the changes which would be made in the regimen of the Nile flood by 
the contemplated conversion of basin irrigation into perennial irri- 
gation. This question was examined very thoroughly by me in 1892 
and 1893 and I give here my arguments for not anticipating any 
serious difficulties. 
We have to consider the effect of the introduction of perennial irri- 
gation on the regime of the Nile. The perfection of the perennial 
irrigation of the Delta north of Cairo will in no way affect the Nile 
in flood. The canals will continue to run as they do at present, 
and the question of conversion in Lower Egypt is therefore quite 
independent of the subject of flood protection. In Upper Egypt, 
however, we have 1,460,000 acres of basin irrigation ; and as each 
acre receives in a low flood 80 cubic metres of water per day, in an 
ordinary flood 130 cubic metres per day, and in an extraordinary flood 
170 cubic metres per day, while the demands of perennial irrigation 
are only 25 cubic metres per acre per day, it will readily be understood 
that we are dealing with a quantity of water which demands the greatest 
attention. 
To foretell with exactitude the anticipated changes in the regime 
of the Nile, it is necessary to know first the daily gauges of the Nile 
at Assuan and Cairo for a period of at least twenty years, and the 
discharges corresponding to these gauges. The difference between 
these discharges represents the consumption of water. We have next 
to determine the amount of water which passes into the canals, the 
amount utilised in filling up the trough of the Nile and covering the 
berms, and the amounts evaporated and absorbed. We know that 
the last three items are constant while the canal discharges are variable 
and depend on the system of irrigation and, if our data are correct, we 
can tell with moderate certainty what changes in the level of the Nile 
will follow certain changes in the system of irrigation. 
