So Tom tried to look dull, which was not at all his natural appearance. He studied the floor as if he expected to find diamonds upon it. He yawned so prodigiously as to attract the attention he was trying to escape. An amateur actor is apt to overact his part. And all the time he was listening with a passionate interest to Colonel Rose's story of the way to freedom. Of course he was glad to try to help make the hope a fact. That night the work began. The kitchen dining-hall was deserted from 10 P.M. to 4 A.M., so it was selected as the field of operation. Below the kitchen was the carpenter-shop. No opening could be made into that without instant detection. On the same floor with the kitchen and just east of it was the hospital. That room must be avoided too. Below the hospital was an unused cellar, half full of rotting straw and all full of squealing rats. It was called "Rat Hell." Outside of it was a small sewer that led to a larger one which passed under the canal and emptied its contents into the James River. These sewers were to be the highway to freedom. The first step must be to get from the kitchen to Rat Hell. To do this it was necessary to dig through a solid stone wall a reversed "S," like this: [Illustration: Reverse S] The upper end of the secret passage was to open into the kitchen fireplace, the lower into Rat Hell. There were fourteen men in the secret, besides Tom. Between them, they had just one tool, an old knife. One of them owned a bit of burlap, used sometimes as a mattress and sometimes as a bed-quilt. It had a new use now. It was spread upon the kitchen hearth in the midnight darkness and a pile of soot was pulled down upon it. Then the mortar between a dozen bricks at the back of the fireplace was cut out with the knife and the bricks pried out of place. This was done by Major A. G. Hamilton, Colonel Rose's chief assistant. He carefully replaced the bricks and flung handfuls of soot over them. He and Rose crept upstairs, carrying the sooty bit of burlap with them, and slept through what was left of the night. The next day was an anxious time for them. When they went down to the kitchen, where a couple of hundred men were gathered, it seemed to them that the marks of their toil by night were too plain not to be seen by some of them. Their nervousness made them poor judges. Nobody saw what had been done. That night, as soon as the last straggler left, Rose and Hamilton again removed the bricks and attacked the stubborn stone behind the fireplace. Fortunately the stones were not large. Bit by bit they were pried out of the loosened mortar.