On September 1st the Japanese, finding that they could not take Port Arthur by assault, settled down to reduce it by an engineering siege. This latter was carried on by means of “sapping and mining,” supported by heavy bombardment, its object being to shake the defense by terrific artillery fire, blow up the parapets and other defenses by subterranean mines, and capture the fortress by fierce assaults delivered from concealed trenches close to the fortifications. Sapping and mining may be described as a method of attack by tunneling. The Japanese found that they could not get into the forts by a rush above ground, so they determined to burrow in below ground. The main attack was directed against the line of forts to the east of the city, or the Russian right center. The first operation was to cut a deep trench, not less than six feet in depth and a dozen or more feet in width, roughly parallel with the line of forts, and at a distance of about 1,000 yards therefrom. From this trench three lines of zigzag trenches were dug in the direction of the principal forts of Ehrlung, Keekwan, and Panlung. These trenches were about six feet deep (deep enough to hide the sappers from view) and eight feet wide (wide enough to allow the troops to march to the assault four abreast). The zigzag consisted of an alternate approach and parallel, the former extending diagonally toward the fortification, the latter parallel with it. The angle of the diagonal approaches was always carefully mapped out by the engineers, and was so laid with reference to the enemy’s forts that it could neither be seen nor reached by shell fire. The digging was done chiefly at night, and the soil was carried back through the excavated trenches in gabions and on stretchers, and dumped out of sight of the enemy. As the parallels were advanced across the valley or level spaces, they were roofed at intervals, with planks covered with soil and grass, so that as the Russians looked out toward the ravine in which the army was supposed to be encamped, there was nothing to indicate that the enemy was cutting a series of covered roadways, right up to the base of the forts themselves. Of course in many cases the trenches were located, and desperate night sorties were made in the endeavor to break up the work. But it went remorselessly forward. When the foot of the fortified slopes was reached, a second great parallel, extending around the whole face of the fortified eastern front, was cut--this latter for the purpose of assembling the troops for the final dash upon the forts. From this parallel the Japanese cut tunnels straight through the hills until they found themselves immediately below the massive parapets of such forts as they wished to reach. Here cross tunnels were cut, parallel with the walls and immediately below them, in which tons of dynamite were placed and the wires laid ready for the great explosion--much of this being done, it must be remembered, entirely unknown to the Russians,