Twice the defenders of the cité endeavoured to sally forth from their retrenchments to drive off the assailants and destroy their works; they met with a warm reception, especially as the Franks could avail themselves of the ruins as a rampart. On their side projectile engines were hurling stones and darts on the rampart walks of the extremities of the curtains that remained standing, and made it impossible for the defenders to remain there. As soon as anyone showed himself, showers of arrows were aimed at him. These rampart walks were repeatedly furnished with mantelets, which were soon thrown down by the stones from the engines. The wooden tower of the besiegers was rising rapidly, and at the end of the second day overtopped that of the retrenchment. An engine was planted at the top, which incessantly discharged heavy stones on the works of the Burgundians. The latter kept the old countermine gallery on the north front; but they had not been able to extend it, because blocks of stone had been thrown by the besiegers into the connecting opening, and were replaced by others when the besieged ventured to remove them. The enemy's miners were no longer heard on this side. The reason was that Secondinus, having become better acquainted with the nature of the soil, had perceived that by digging deeper he found a stratum of sand easy to work in and carry away. From the old abortive gallery, however, which the besieged could not speedily enter, he had conducted two oblique tunnels, in an inverse direction and at a deep level, descending into the sand, under the foundations of the curtain; one of them, A, gradually rose again obliquely as far as the inner side of the ramparts (Fig. 34). He expected in this way to make an entrance into the cité in any case. [Illustration: FIG. 34.] But a thick bed of limestone prevented the ceiling from being speedily penetrated. The gallery was far enough from that marked B, intended to undermine the curtain wall, not to be destroyed by its fall, and he reckoned on making use of it on occasion.