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the other. Each depression may be 3 kilometres in width -where it is wide 
and a few hundred metres where it is narrow, so that the flooded valley 
may have a width of 6 kilometres in places. The ridges are about 3 metres 
wide, and broken by openings through which the water passes in and 
out of the side marshy depressions. The depressions are covered by 
a dense growth of reeds and papyrus. When the reeds are burnt one 
can traverse the marshes on foot. South of Kaka (200 kilometres 
north of the Sobat mouth) the depressions are lower than they are 
further north, which, to me, goes to prove that the channel of to-day is 
formed within the channel of old days when the Blue Nile was 
flowing south into the Sudd region. At Gebelain (250 kilometres 
north of Kaka) the side depressions contract and the forests come 
nearer the river. At the Abu Zeid ford, 50 kilometres further to the 
north, is a serious obstacle to navigation when the river is low, in 
the shape of a very broad sheet of shingle studded thick with fresh- 
water oysters. This bar is 6 kilometres long, as hard as stone, and 
has in very low summer supplies a depth of water over it of only 
50 centimetres. It is a wonder that a channel has not been blasted 
through it. The swamping now visibly decreases and the width of 
the river varies from 700 to 900 metres. Some 25 kilometres north 
of Abu Zeid the papyrus and sudd grasses disappear, and though 
there is flooding there are no swamps. We have now some well 
cultivated islands in the river for the negroes have come to an end and 
the Arabs inhabit the country. The summer channel may be now 
considered as 700 metres wide and the flood channel as 1300 metres. 
The summer depth of water is 4 metres. At Duem, 220 kilometres 
south of Khartoum, the width of the channel widens from 900 to 1000 
and further north to 1500 metres, and finally to 3000 metres. We 
are in a lake rather than in a river, and in flood when the waters of 
the Blue Nile travel 300 kilometres up the White Nile, and wait for a 
fall in the Blue Nile to discharge themselves into the Nile, we are indeed 
in a pulsating lake and not in a river. It must have been in September, 
when the discharge of the Blue Nile had fallen from some 11,000 to 
6,000 cubic metres per second, and the stored-up waters in the valley 
of the White Nile were forcing themselves down to take the place of 
those cut off from the Blue Nile, that Linant Pasha took his discharges 
of the Blue and White Niles and found them some 6000 and 5000 
cubic metres per second respectively. The same remark may be 
made about M. Chelu’s discharge of the White Nile at Khartoum of 
