convinced that success in my Nile expedition would be impossible without
a knowledge of Arabic. My dragoman had me completely in his power, and I
resolved to become independent of all interpreters as soon as possible.
I therefore arranged a plan of exploration for the first year, to
embrace the affluents to the Nile from the Abyssinian range of
mountains, intending to follow up the Atbara river from its junction
with the Nile in lat. 17 degrees 37 minutes (twenty miles south of
Berber), and to examine all the Nile tributaries from the southeast as
far as the Blue Nile, which river I hoped ultimately to descend to
Khartoum. I imagined that twelve months would be sufficient to complete
such an exploration, by which time I should have gained a sufficient
knowledge of Arabic to enable me to start from Khartoum for my White
Nile expedition. Accordingly I left Berber on the 11th June, 1861, and
arrived at the Atbara junction with the Nile on the 13th.

There is no portion of the Nile so great in its volume as that part
situated at the Atbara junction. The river Atbara is about 450 yards in
average width, and from twenty-five to thirty feet deep during the rainy
season. It brings down the entire drainage of Eastern Abyssinia,
receiving as affluents into its main stream the great rivers Taccazy (or
Settite), in addition to the Salaam and Angrab. The junction of the
Atbara in lat. 17 degrees 37 minutes N. is thus, in a direct line from
Alexandria, about 840 geographical miles of latitude, and, including the
westerly bend of the Nile, its bed will be about eleven hundred miles in
length from the mouth of its last tributary, the Atbara, until it meets
the sea. Thus, eleven hundred miles of absorption and evaporation
through sandy deserts and the delta must be sustained by the river
between the Atbara junction and the Mediterranean: accordingly there is
an immense loss of water; and the grandest volume of the Nile must be
just below the Atbara junction.