— 15 — 
The White Nile falls 14 metres in 840 kilometres and has two slopes 
in flood ; 5 5 7 77 in its upper reach, and then iooooq - 
The Blue Nile falls 1370 metres in 1370 kilometres, which may 
roughly be divided into three reaches. The first from Lake Tsana to 
Rosaires on a length of 750 kilometres 777 , the second Rosaires to 
Sennaar 7777 , an d the third 7777 . These are very approximate indeed. 
The Atbara falls 1640 metres in 880 kilometres. In the first 300 
kilometres the slope is 777 ; i n the next 300 kilometres the slope is 7777 ^ 
and in the last reach of 280 kilometres it is 7 ^ 77 . These are approximate. 
The Main Nile from Khartoum to Assuan falls 295 metres in 1810 
kilometres; the so-called six cataracts occupy 565 kilometres with a 
slope of 3 77 7 ; and the ordinary channel occupies 1245 kilometres and 
has a slope of 12 ^ . From Assuan to the Barrage, on a length of 970 
kilometres, the Nile falls 76 metres with a mean slope of ^ 3 * 00 . The 
Rosettaand Damietta branches are each about 240 kilometres long and have 
a slope in flood of l 3 q 0Q -, and of 77577 in extraordinarily high floods. 
From the sources of the Kagera river to the sea, on a length of 6350 
kilometres, the Nile falls 2000 metres, or has a slope of 7777 . From 
Lake Victoria to the sea the length is 5535 kilometres and the fall 
1129 metres, or the slope is 7777 . 
Table III of Appendix C. gives the velocities of the river in flood 
and low supply, in metres per second and kilometres per day, and also 
the time occupied in traversing the different reaches. There are two 
breaks. The first is at Lake Choga and the second is at Lake Albert. 
As the Victoria Nile traverses the eastern arm of the many-armed and 
peculiar Lake Choga with a perceptible current, and as, moreover, the 
lake is very shallow, we may give some figure to the velocity and make 
it half that of the Bahr Gazelle which is *20 metres per second and is 
considered perceptible. With a velocity of TO metres per second or 8 
kilometres per day, the 80 kilometres of the lake would be traversed 
in 10 days. The time of traverse from Lake Victoria to Lake Albert 
would be 15 days. With Lake Albert it is very different. A reference 
to Plate V will show that it takes the Victoria Nile 5 months to fill up 
Lake Albert before the Albert Nile can carry off the waters of the 
Victoria Nile, gauge for gauge. Under these conditions it will be wise 
to stop at Lake Albert and begin a new calculation from this lake. 
The Albert Nile takes 22 days in flood and 25 days in low supply to 
traverse the distance from Lake Albert to the Sobat mouth. The White 
Nile takes 21 days in flood and 28 days in low supply to reach Khartoum. 
