Brick after brick yielded to the vigorous and well-timed efforts of Ulpius. He had already made a cavity, in an oblique direction, large enough to creep through, and was preparing to penetrate still further, when a portion of the rotten material of the interior of the wall suddenly yielded in a mass to a chance pressure of his iron bar, and slowly sunk down inwards into a bed which, judging by such faint sounds as were audible at the moment, must have been partly water, and partly marshy earth and rotten brick-work. After having first listened, to be sure that the slight noise caused by this event had not reached the ears or excited the suspicions of the careless sentinels, Ulpius crept into the cavity he had made, groping his way with his bar, until he reached the brink of a chasm, the depth of which he could not probe, and the breadth of which he could not ascertain. He lingered irresolute; the darkness around him was impenetrable; he could feel toads and noisome animals crawling over his limbs. The damp atmosphere of the place began to thrill through him to his very bones; his whole frame trembled under the excess of his past exertions. Without light, he could neither attempt to proceed, nor hope to discover the size and extent of the chasm which he had partially laid open. The mist was fast vanishing as the night advanced: it was necessary to arrive at a resolution ere it would be too late. He crept out of the cavity. Just as he had gained the open air, the sentinel halted over the very spot where the Pagan stood, and paused suddenly in his song. There was an instant's interval of silence, during which the inmost soul of Ulpius quailed beneath an apprehension as vivid, as that which had throbbed in the heart of the despised lizard, whose flight had guided him to his discovery at the wall. Soon, however, he heard the voice of the soldier calling cheerfully to his fellow sentinel, 'Comrade, do you see the moon? She is rising to cheer our watch!' Nothing had been discovered!--he was still safe! But if he stayed at the cavity till the mists faded before the moonlight, could he be certain of preserving his security? He felt that he could not! What mattered a night more or a night less, to such a project as his? Months might elapse before the Goths retired from the walls. It was better to suffer delay than to risk discovery. He determined to leave the place, and to return on the following night provided with a lantern, the light of which he would conceal until he entered the cavity. Once there, it could not be perceived by the sentinels above--it would guide him through all obstacles, preserve him through all dangers. Massive as it was, he felt convinced that the interior of the wall was in as ruinous a condition as the outside. Caution and perseverance were sufficient of themselves to insure to his efforts the speediest and completest success.