Nicholson, the London engineer; long, quaint, kind-hearted ‘Roddy’ Owen—­all filled graves in Halfa cemetery or at the foot of Firket mountain.  At length the epidemic was stamped out, and by the middle of August it had practically ceased to be a serious danger.  But the necessity of enforcing quarantine and other precautions had hampered movement up and down the line of communications, and so delayed the progress of the preparations for an advance.

Other unexpected hindrances arose.  Sir H. Kitchener had clearly recognised that the railway, equipped as it then was, would be at the best a doubtful means for the continual supply of a large force many miles ahead of it.  He therefore organised an auxiliary boat service and passed gyassas and nuggurs [native sailing craft] freely up the Second Cataract.  During the summer months, in the Soudan, a strong north wind prevails, which not only drives the sailing-boats up against the stream—­sometimes at the rate of twenty miles a day—­but also gratefully cools the air.  This year, for forty consecutive days, at the critical period of the campaign, the wind blew hot and adverse from the south.  The whole auxiliary boat service was thus practically arrested.  But in spite of these aggravating obstacles the preparations for the advance were forced onwards, and it soon became necessary for the gunboats and steamers to be brought on to the upper reach of the river.

The Second Cataract has a total descent of sixty feet, and is about nine miles long.  For this distance the Nile flows down a rugged stairway formed by successive ledges of black granite.  The flood river deeply submerges these steps, and rushes along above them with tremendous force, but with a smooth though swirling surface.  As the Nile subsides, the steps begin to show, until the river tumbles violently from ledge to ledge, its whole surface for miles churned to the white foam of broken water, and thickly studded with black rocks.  At the Second Cataract, moreover, the only deep channel of the Nile is choked between narrow limits, and the stream struggles furiously between stern walls of rock.  These dark gorges present many perils to the navigator.  The most formidable, the Bab-el-Kebir, is only thirty-five feet wide.  The river here takes a plunge of ten feet in seventy yards, and drops five feet at a single bound.  An extensive pool above, formed by the junction of two arms of the river, increases the volume of the water and the force of the stream, so that the ‘Gate’ constitutes an obstacle of difficulty and danger which might well have been considered insurmountable.