degrees 30 minutes, and by the Atbara, in lat. 17 degrees 37 minutes.
The Blue Nile during the dry season is so reduced that there is not
sufficient water for the small vessels engaged in transporting produce
from Sennaar to Khartoum; at that time the water is beautifully clear,
and, reflecting the cloudless sky, its colour has given it the
well-known name of Bahr el Azrak, or Blue River. No water is more
delicious than that of the Blue Nile; in great contrast to that of the
White river, which is never clear, and has a disagreeable taste of
vegetation. This difference in the quality of the waters is a
distinguishing characteristic of the two rivers: the one, the Blue Nile,
is a rapid mountain stream, rising and falling with great rapidity; the
other is of lake origin, flowing through vast marshes. The course of the
Blue Nile is through fertile soil; thus there is a trifling loss by
absorption, and during the heavy rains a vast amount of earthy matter of
a red colour is contributed by its waters to the general fertilizing
deposit of the Nile in Lower Egypt.

The Atbara, although so important a river in the rainy season of
Abyssinia, is perfectly dry for several months during the year, and at
the time I first saw it, June 13, 1861, it was a mere sheet of glaring
sand; in fact a portion of the desert through which it flowed. For
upwards of one hundred and fifty miles from its junction with the Nile,
it is perfectly dry from the beginning of March to June. At intervals of
a few miles there are pools or ponds of water left in the deep holes
below the general average of the river's bed. In these pools, some of
which may be a mile in length, are congregated all the inhabitants of
the river, who as the stream disappears are forced to close quarters in
these narrow asylums; thus, crocodiles, hippopotami, fish, and large
turtle are crowded in extraordinary numbers, until the commencement of
the rains in Abyssinia once more sets them at liberty by sending down a