After a preliminary ten rounds had been fired, the wall was closely inspected. It was seen that infantry might have clambered over the debris to the top of the structure and jumped down upon the other side. A strange feature was that wherever the "Lyddite" explosive failed to detonate the stones and ground around had been transformed to a deep chrome colour. The battery was moved closer, to about 350 yards from the wall, and the firing was recommenced at that range. Much better results were obtained, and the upper part of the wall was knocked away, and easy, practicable breaches made. One of the other advantages of these new guns is that with reduced firing charges they become reliable mortars, and the high explosive shells can be dropped over a wall or building, so as to drive the defenders from their works. Not a man would have escaped injury had there been an enemy behind the wall, for blocks of stone were scattered in all directions. When the howitzers had finished their practice, six rounds were fired from two 40-lb. Armstrong guns, which were also ordered to assist in breaching Omdurman's walls. Next to the 7-lb. screw guns the 40-lb. Armstrong is reputed to be the most accurate shooting cannon in the British service. Mounted on lofty carriages, these siege guns were laid to fire at 800 yards range. Oddly enough, one of the 40-lbs. scored as high a percentage of misses as the howitzers. The great velocity of the 40-lb. shells, filled with the slower-bursting gunpowder, carried them well into the part of the wall aimed at, with the result that, in a few seconds, they made a good breach. The morning's experiments were concluded by a detachment of the Royal Irish Fusiliers, under Captain Churches, firing their Maxims against targets representing bands of dervishes, the dummy enemy being, as usual, riddled with bullets. From Cairo to Dakhala, evidence was not lacking that the form and movement of preparations for the general advance were growing apace. Every train and boat going south was overloaded with officers, men, and transport animals, together with munitions of war galore for the campaign. The gunboats and deserters brought in reports that the dervishes were concentrating at Omdurman. The strongly defensible positions of Shabluka, together with the mud forts, had been evacuated by the dervishes. Very quickly the Sirdar sent small bodies of troops up stream to occupy suitable positions for wood-cutting and forming advance camps. In that way the river pass at the Sixth Cataract was seized without the long anticipated fight for that difficult bit of country. The Nile highway was at length in the Sirdar's undisputed possession up to within thirty miles of Omdurman.