In a fortnight the besiegers' tunnels were near enough for the workmen to hear the blows of the pickaxes in the rock. Clodoald was then in a condition to leave his dwelling; he examined what had been done, stopped the work, and listened attentively. He judged that the enemy's miners were digging obliquely under the wall, near the north gate (Fig. 29), while the countermine of the besieged followed the direction A B. [Illustration: FIG. 29.] He thought he also perceived that the enemy's tunnel was on a higher level than his own. This seemed favourable to the plan he was intending to adopt, and with a view to greater safety, he sunk the floor of the countermine-tunnel still lower. On visiting the base of the ramping wall he heard no noise at this point, although his lieutenants said they had heard mining towards the upper third of the wall during the preceding days. The countermine-tunnel was also commenced opposite to the place where they thought they had heard the enemy's miners. Clodoald ordered a suspension of the work till the besiegers' operations were clearly understood. Next day, on the north front, it became evident that the countermine-tunnel was crossing that of the enemy, for the steps of the pioneers were heard above the ceiling. Clodoald then had the ceiling shored up along the sides of the tunnel, and ordered that the layers of stone forming the ceiling should be noiselessly removed by levers and crowbars, so as to render it as thin as possible below the point where footsteps had been heard. When this had been done to the extent of leaving only a very thin layer of rock, Clodoald had dry faggots, resin, tar, and all the inflammable materials that could be got, heaped up in the countermine tunnel; then, promising the most skilful of his miners a large reward on succeeding, he told him to break down this crust, and as soon as he perceived an opening, however small, to set fire to the faggots, retiring towards the entrance. In fact, a few minutes after the order had been given, the miner appeared at the entrance of the shaft, followed by a thick smoke. He reascended quickly, and this opening was stopped with planks and earth. From the hole made below the floor of the besiegers' gallery the smoke was rising into the tunnel, and suffocating the miners. They tried to stop up this orifice, but the necessary materials were not at hand; and the flame soon mounted high, as the hole produced a draft. The heat burst the stone to pieces, and the opening was becoming larger. The mining gallery was soon so filled with smoke that it was no longer possible to stay there and some of the miners fell suffocated before they could gain the somewhat distant mouth of the tunnel.