"I do not think it," retorted Benvenuto, with the confident smile which caused his host to use strong language. The governor went out, cursing Benvenuto roundly, and the next morning he issued orders that his cell should be inspected every two hours, night and day. This rigid inspection was continued for a month; but at the end of that time, as there was no apparent reason to believe that Benvenuto was even thinking of escape, the vigilance of his keepers was somewhat relaxed. Benvenuto, however, had employed the month in accomplishing a terrible task. As we have said, he minutely examined his cell immediately after he was first consigned to it, and from that moment his mind was made up as to the manner of his escape. His window was barred, and the bars were too strong to be removed with the hand or with his modelling tool, the only iron instrument he possessed. The chimney narrowed so toward the top that the prisoner must needs have had the fairy Melusine's power of transforming herself into a serpent to pass through it. The door remained. Ah, the door! Let us see how the door was made. It was a heavy oaken door two fingers thick, secured by two locks and four bolts, and sheathed on the inside with iron plates kept in place by nails at the top and bottom. It was through that door that the escape must be effected. Benvenuto had noticed in the corridor, a few steps from the door, the stairway leading to the platform. At intervals of two hours he heard the footsteps of the relieving sentinel going up, then the steps of the other coming down; after which he would hear nothing more for another two hours. The question for him to solve, then, was simply this: how to reach the other side of that door, which was secured by two locks and four bolts, and furthermore sheathed on the inside with iron plates kept in place by nails at the top and bottom. The solution of this problem was the task to which Benvenuto had devoted the month in question. With his modelling tool, which was of iron, he removed, one by one, the heads of all the nails, save four above and four below, which he left until the last day: then, in order that his work might not be detected, he replaced the missing heads with exactly similar ones, modelled in clay and covered with iron filings, so that it was impossible for the keenest eye to distinguish the false from the true. As there were, at top and bottom together, some sixty nails, and as it took at least one hour, and sometimes two, to decapitate each nail, the magnitude of the task may be understood. Every evening, when everybody had retired, and nothing could be heard save the footsteps of the sentinel walking back and forth over his head, he built a great fire on the hearth, and piled glowing embers against the iron plates on his door; the iron became red hot, and gradually transformed to charcoal the wood upon which it was applied; but no indication of the carbonizing process appeared on the other side of the door.