Partly influenced by such considerations, and partly that they were occupied with pleasanter matters, the authorities had resolved on leaving him where he was for the night, though Carlos was ignorant of this. He had, however, prepared himself for either contingency. Should they convey him back to the Presidio, he would seek the best opportunity that offered, and risk his life in a bold effort to escape. Should he be permitted to remain in the Calabozo, he would wait till the guard had visited him--then set to work upon the wall after they had gone out. In the event of being detected while at work, but one course remained,--run the gauntlet of the guard, and cut his way through their midst. His escape was not an affair of such improbability. A determined man with a long knife in his grasp--one who will yield only to death--is a difficult thing to secure under any circumstances. Such an one will often effect his freedom, even when hemmed in by a host of enemies. With Carlos, however, the probabilities of escape were much greater. He was individually strong and brave, while most of his enemies were physically but pigmies in comparison. As to their courage, he knew that once they saw him with his hands free and armed, they would make way for him on all sides. What he had most to fear was the bullets of their carbines; but he had much to hope from their want of skill, and the darkness would favour him. For more than an hour he lay along the banqueta, turning over in his mind the chances of regaining his liberty. His reflections were interrupted by an unusual stir outside his prison. A fresh batch of soldiers had arrived at the door. Carlos' heart beat anxiously. Was it a party come to conduct him to the Presidio? It might be so. He waited with painful impatience listening to every word. To his great joy it proved to be the arrival of the relief-guard; and he had the satisfaction of hearing, by their conversation, that they had been detailed to guard him all night in the Calabozo. This was just the very thing he desired to know. Presently the door was unlocked and opened, and several of the men entered. One bore a lantern. With this they examined him--uttering coarse and insulting remarks as they stood around. They saw that he was securely bound! After a while all went out and left him to himself. The door was of course re-locked, and the cell was again in perfect darkness. Carlos lay still for a few minutes, to assure himself they were not going to return. He heard them place the sentries by the door, and then the voices of the greater number seemed borne off to some distance. Now was the time to begin his work. He hastily cast the cords from his hands and feet, drew the long knife from his breast, and attacked the adobe wall.