A wisp of straw, which he had carelessly thrown against them the preceding day, as he paced to and fro, remained where he had cast it, though it must have been displaced by the slightest motion of either of the doors. This was evidence that could not be disputed; and it followed there must be some secret machinery in the walls by which a person could enter. He inspected them closely. They appeared to him one solid and compact mass of iron; or joined, if joined they were, with such nice art that no mark of division was perceptible. Again and again he surveyed them, and the floor and the roof, and that range of visionary windows, as he was now almost tempted to consider them: he could discover nothing, absolutely nothing, to relieve his doubts or satisfy his curiosity. Sometimes he fancied that altogether the dungeon had a more contracted appearance,—that it looked smaller; but this he ascribed to fancy, and the impression naturally produced upon his mind by the undeniable disappearance of two of the windows. With intense anxiety, Vivenzio looked forward to the return of night; and, as it approached, he resolved that no treacherous sleep should again betray him. Instead of seeking his bed of straw, he continued to walk up and down his dungeon till daylight, straining his eyes in every direction through the darkness, to watch for any appearances that might explain these mysteries. While thus engaged, and, as nearly as he could judge (by the time that afterward elapsed before the morning came in), about two o’clock, there was a slight, tremulous motion of the floors. He stooped. The motion lasted nearly a minute: but it was so extremely gentle that he almost doubted whether it was real, or only imaginary. He listened. Not a sound could be heard. Presently, however, he felt a rush of cold air blow upon him; and, dashing toward the quarter whence it seemed to proceed, he stumbled over something which he judged to be the water ewer. The rush of cold air was no longer perceptible; and, as Vivenzio stretched out his hands, he found himself close to the walls. He remained motionless for a considerable time; but nothing occurred during the remainder of the night to excite his attention, though he continued to watch with unabated vigilance.