the force of the stream to a
depth of twenty or thirty feet below the level of the bed. Accordingly
these holes become reservoirs of water when the river is otherwise
exhausted. In such asylums all the usual inhabitants of this large river
are crowded together in a comparatively narrow space. Although these
pools vary in size, from only a few hundred yards to a mile in length,
they are positively full of life; huge fish, crocodiles of immense size,
turtles, and occasionally hippopotami, consort together in close and
unwished-for proximity. The animals of the desert--gazelles, hyenas, and
wild asses--are compelled to resort to these crowded drinking-places,
occupied by the flocks of the Arabs equally with the timid beasts of
the chase. The birds that during the cooler months would wander free
throughout the country are now collected in vast numbers along the
margin of the exhausted river; innumerable doves, varying in species,
throng the trees and seek the shade of the dome-palms; thousands of
desert grouse arrive morning and evening to drink and to depart; while
birds in multitudes, of lovely plumage, escape from the burning desert
and colonize the poor but welcome bushes that fringe the Atbara River.

After several days' journey along the bank of the Atbara we halted at a
spot called Collodabad, about one hundred and sixty miles from the Nile
junction. A sharp bend of the river had left a deep pool about a mile in
length, and here a number of Arabs were congregated, with their flocks
and herds.

On the evening of June 23d I was lying half asleep upon my bed by the
margin of the river, when I fancied that I heard a rumbling like
distant thunder. I had not heard such a sound for months, but a low,
uninterrupted roll appeared to increase in volume, although far distant.
Hardly had I raised my head to listen more attentively when a confusion
of voices arose from the Arabs' camp, with a sound of many feet, and
in a few minutes they rushed into my camp, shouting to my men in the
darkness, "El Bahr! El Bahr!" (the river! the river!)

We were up in an instant, and my interpreter, Mahomet, in a state of
intense confusion, explained that the river was coming down, and that
the supposed distant thunder was the roar of approaching water.

Many of the people were asleep on the clean sand on the river's bed;
these were quickly awakened by the Arabs, who rushed down the steep bank
to save the skulls of two hippopotami that were e