On the 29th the forces remained halted opposite Um Teref, and only the Egyptian cavalry went out to reconnoitre. They searched the country for eight or nine miles, and Colonel Broadwood returned in the afternoon, having found a convenient camping-ground, but nothing else. During the day the news of two river disasters arrived--the first to ourselves, the second to our foes. On the 28th the gunboat Zafir was steaming from the Atbara to Wad Hamed, intending thereafter to ascend the Shabluka Cataract. Suddenly--overtaken now, as on the eve of the advance on Dongola, by misfortune--she sprang a leak, and, in spite of every effort to run her ashore, foundered by the head in deep water near Metemma. The officers on board--among whom was Keppel, the commander of the whole flotilla--had scarcely time to leap from the wreck, and with difficulty made their way to the shore, where they were afterwards found very cold and hungry. The Sirdar received the news at Royan. His calculations were disturbed by the loss of a powerful vessel; but he had allowed for accidents, and in consequence accepted the misfortune very phlegmatically. The days of struggling warfare were over, and the General knew that he had a safe margin of strength. The other catastrophe afflicted the Khalifa, and its tale was brought to the advancing army by the Intelligence spies, who to the last--even when the forces were closing--tried to pass between them. Not content with building batteries along the banks, Abdullah, fearing the gunboats, had resolved to mine the river. An old officer of the old Egyptian army, long a prisoner in Omdurman, was brought from his chains and ordered to construct mines. Two iron boilers were filled with gunpowder, and it was arranged that these should be sunk in the Nile at convenient spots. Buried in the powder of each was a loaded pistol with a string attached to the trigger. On pulling the string the pistol, and consequently the mine, would be exploded. So the Khalifa argued; nor was he wrong. It was resolved to lay one mine first. On the 17th of August the Dervish steamer Ismailia moved out into the middle of the Nile, carrying one of the boilers fully charged and equipped with pistol detonator. Arrived at the selected spot, the great cylinder of powder was dropped over the side. Its efficiency as a destructive engine was immediately demonstrated, for, on the string being pulled by accident, the pistol discharged itself, the powder exploded, and the Ismailia and all on board were blown to pieces.