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course of the Nile, and compare the discharges at Tewfikieh, Khartoum, 
Assuan, Cairo and at the tails of the Rosetta and Damietta branches 
during the time of low supply we can only admire the perspicacity of 
the greatest hydraulic engineer of the last century. 
26. Nile water. — For the following information I am principally 
indebted to M. J. Barois’ “ Les irrigations en Egypte” just published, 
and to an article by Mr Gf. P. Foaden in the Journal of the Khedivial 
Agricultural Society for January 1903. The colour of Nile water is 
generally a pale yellow, but in June, when the first indications of the 
coming flood are given by a continuous gentle rise of the river from 
its minimum gauge, the water changes to green and remains so for 
two or three weeks. This green water has a very disagreable taste and 
odour, and is especially objectionable when the Nile has been very low 
and the rise is a slow one. In June 1900 it was extraordinarily bad, 
and the river water was so poor in oxygen that standing on Kasr-el-Nil 
bridge at Cairo one could see the surface of the water covered with 
fish which apparently could only live near the surface. In the deep 
reaches near Ivalabsha in Nubia, the fish died in myriads. This green 
water is attributed by some to the immense amount of vegetable matter 
brought down by the White Nile from the Sudd region. Some say 
that it comes principally with the first rise of the Sobat river. But 
the generally accepted theory to-day is that the green water is the 
result of vegetable growths from germs is the water itself, and that 
wherever or whenever the current becomes exceedingly slack they 
multiply greatly. Upstream of the Assuan dam in June 1903 the 
water was extraordinarily green and exceedingly objectionable. As it 
was shot out of the upper sluices of the dam and broken up into spray 
on the downstream side of the dam it became so purified that I found 
it difficult to understand that the water flowing past Elephantine 
Island was what I had seen at Shellal. The green water is followed 
by the red water of the Nile flood, which has always thoroughly 
established itself at Cairo by the 1st of August. This red water comes 
from the scourings of the volcanic plateau of Abyssinia by the Blue Nile 
and the Atbara. Rich in mud and rich in manures, this red water is 
the creator of Egypt. Egypt is nothing more than the deposit left by 
the Nile in flood. The water is most heavily charged with detritus 
in August, less in September, and still less in October. 
Many analyses have been made of Nile water. Following M. Barois, 
I place side by side the analysis of Dr. Letheby of 1874/75 and 
