The jailer continued his search and on the other side of the trousers waist band found another piece of steel identical with the first. The edges showed where they had been worn against the bars of the window.
"You couldn't saw a way through those bars with these," said the warden.
"I could have," said The Thinking Machine firmly.
"In six months, perhaps," said the warden, good-naturedly.
The warden shook his head slowly as he gazed into the slightly flushed face of his prisoner.
"Ready to give it up?" he asked.
"I haven't started yet," was the prompt reply.
Then came another exhaustive search of the cell. Carefully the two men went over it, finally turning out the bed and searching that. Nothing. The warden in person climbed upon the bed and examined the bars of the window where the prisoner had been sawing. When he looked he was amused.
"Just made it a little bright by hard rubbing," he said to the prisoner, who stood looking on with a somewhat crestfallen air. The warden grasped the iron bars in his strong hands and tried to shake them. They were immovable, set firmly in the solid granite. He examined each in turn and found them all satisfactory. Finally he climbed down from the bed.
"Give it up, professor," he advised.