came to the air-chamber, as I had calculated, and found it six feet wide
by four feet high, and running the entire length of the range of cells.
The cement and brick taken out in effecting an entrance to the chamber
were placed in my bed-tick, upon which I slept during the progress of
this portion of the work, after which the material was removed to the
chamber. We found the chamber heavily grated at the end, against which a
large quantity of coal had been heaped, cutting off any chance of exit
in that way. We then began a tunnel, running it at right angles from the
side of the chamber, and almost directly beneath my cell. We cut through
the foundation wall, five feet thick, of the cell block; through twelve
feet of grouting, to the outer wall of the east wing of the prison;
through this wall, six feet in thickness; and four feet up near the
surface of the yard, in an unfrequented place between this wing and the
female department of the prison.

[Illustration: EXTERIOR OF THE PRISON. B--EXIT FROM TUNNEL.]

During the progress of the work, in which we were greatly assisted by
several of our comrades who were not to go out, notably among them
Captain Thomas W. Bullitt of Louisville, Kentucky, I sat at the entrance
to my cell studiously engaged on Gibbon's Rome and in trying to master
French. By this device I was enabled to be constantly on guard without
being suspected, as I had pursued the same course during the whole
period of my imprisonment. Those who did the work were relieved every
hour. This was accomplished, and the danger of the guards overhearing
the work as they passed obviated, by adopting a system of signals, which
consisted in giving taps on the floor over the chamber. One knock was to
suspend work, two to proceed, and three to come out. On one occasion, by
oversight, we came near being discovered. The prisoners were taken out
to their meals by ranges, and on this day those confined in the first