Having no confidence in the bulk of his force, it is not surprising that Gordon resorted to every artifice within engineering science to compensate for the shortcomings of his army. He surrounded Khartoum--which on one side was adequately defended by the Nile and his steamers--on the remaining three sides with a triple line of land mines connected by wires. Often during the siege the Mahdists attempted to break through this ring, but only to meet with repulse, accompanied by heavy loss; and to the very last day of the siege they never succeeded in getting behind the third of these lines. Their efficacy roused Gordon's professional enthusiasm, and in one passage he exclaims that these will be the general form of defence in the future. During the first months of the siege, which began rather in the form of a loose investment, the Nile was too low to allow of his using the nine steamers he possessed, but he employed the time in making two new ones, and in strengthening them all with bulwarks of iron plates and soft wood, which were certainly bullet-proof. Each of these steamers he valued as the equivalent of 2000 men. When it is seen how he employed them the value will not be deemed excessive, and certainly without them he could not have held Khartoum and baffled all the assaults of the Mahdi for the greater part of a year. After this experience Gordon would risk no more combats on land, and on 25th March he dismissed 250 of the Bashi-Bazouks who had behaved so badly. Absolutely trustworthy statistics are not available as to the exact number of troops in Khartoum or as to the proportion the Black Soudanese bore to the Egyptians, but it approximates to the truth to say that there were about 1000 of the former to 3000 of the latter, and with other levies during the siege he doubled this total. For these and a civilian population of nearly 40,000 Gordon computed that he had provisions for five months from March, and that for at least two months he would be as safe as in Cairo. By carefully husbanding the corn and biscuit he was able to make the supply last much longer, and even to the very end he succeeded in partially replenishing the depleted granaries of the town. There is no necessity to repeat the details of the siege during the summer of 1884. They are made up of almost daily interchanges of artillery fire from the town, and of rifle fire in reply from the Arab lines. That this was not merely child's play may be gathered from two of Gordon's protected ships showing nearly a thousand bullet-marks apiece. Whenever the rebels attempted to force their way through the lines they were repulsed by the mines; and the steamers not only inflicted loss on their fighting men, but often succeeded in picking up useful supplies of food and grain. No further reverses were reported, because Gordon was most careful to avoid all risk, and the only misfortunes occurred in Gordon's rear, when first Berber, through the treachery of the Greek