Zeno had found time to look about him during the conversation, as far as the light of the lanterns and the men who crowded upon him allowed him to see. He had understood very soon that he was not in the cellar of a ruined house, as he had at first supposed, but in one of those great disused cisterns, of which there are several in Constantinople, and of which two may still be seen. Centuries had passed since there had been water in this one, and the dust lay thick on the paved floor. Two or three score columns of grey marble supported the high vaulted roof, in which Zeno guessed that there was no longer any visible opening to the outer air. Yet air there was, in abundance, for it entered by the narrow entrance through which Zeno had been carried in, and probably found its way out through the disused aqueduct which had once supplied the water, and which still communicated with some distant exit. Zeno could only guess at this from his experience of fortresses, which always contained some similar cistern; every one he had seen was provided with openings, almost always both at the top; a few had staircases in order that men might more conveniently go down to clean them when they were empty. His captors left him reluctantly at the bidding of their chief. They set one lantern against a pillar and filed out, carrying away the other. Zeno listened to their departing footsteps for a moment, when the last man had gone out, and then he went quickly to the entrance and listened again. In two or three minutes he heard what he expected; a heavy door creaked and was shut with a loud noise that boomed down the inclined passage. Then came another sound, which was not that of bolt or bar, and was worse to hear. The men were rolling big loose stones against the door to keep it shut--two, three, more, a dozen at least, a weight no one man could push outward. Then there was no more noise, and Zeno was alone. His situation was serious, and his face was very thoughtful as he went back to the lantern and picked up one of the two cloaks Tocktamish had left him. He put it on and drew it closely round him, for he was beginning to feel cold in spite of the heavy guardsman's tunic he wore over his own clothes.