Something about Tunneling.
We grew very familiar with the occult science of tunneling. Its modus operandi is this: the workman, having sunk a hole in the ground three, six, or eight feet, as the case may require, strikes off horizontally, lying flat on his face, and digging with whatever tool he can find—usually a case-knife. The excavation is made just large enough for one man to creep through it. The great difficulty is, to conceal the dirt. In Salisbury, however, this obstacle did not exist, for many of the prisoners lived in holes in the ground, which they were constantly changing or enlarging. Hence the yard abounded in hillocks of fresh earth, upon which that taken from the tunnels could be spread nightly without exciting notice.
After the great influx of prisoners of war in October, a large tunneling business was done. I knew of fifteen in course of construction at one time, and doubtless there were many more. The Commandant adopted an ingenious and effectual method of rendering them abortive.
In digging laterally in the ground, at the distance of thirty or forty feet the air becomes so foul that lights will not burn, and men breathe with difficulty. In the great tunnel sixty-five feet long, by which Colonel Streight and many other officers escaped from Libby prison, this embarrassment was obviated by a bit of Yankee ingenuity. The officers, with tacks, blankets, and boards, constructed a pair of huge bellows, like those used by blacksmiths. Then, while one of them worked with his case-knife, progressing four or five feet in twelve hours, and a second filled his haversack with dirt and removed it (of course backing out, and crawling in on his return, as the tunnel was a single track, and had no turn-table), a third sat at the mouth pumping vigorously, and thus supplied the workers with fresh air.
The Tunnelers Ingeniously Baffled.
At Salisbury this was impracticable. I suppose a paper of tacks could not have been purchased there for a thousand dollars. There were none to be had. Of course we could not pierce holes up to the surface of the ground for ventilation, as that would expose every thing.
Originally there was but one line of guards—posted some twenty-five feet apart, upon the fence which surrounded the garrison, and constantly walking to and fro, meeting each other and turning back at the limits of each post. Under this arrangement it was necessary to tunnel about forty feet to go under the fence, and come up far enough beyond it to emerge from the earth on a dark night without being seen or heard by the sentinels.
When the Commandant learned (through prisoners actually suffering for food, and ready to do almost any thing for bread) that tunneling was going on, he tried to ascertain where the excavations were located; but in vain, because none of the shaky Unionists had been informed. Therefore he established a second line of guards, one hundred feet outside of those on the fence, who also paced back and forth in the same manner until they met, forming a second line impervious to Yankees. This necessitated tunneling at least one hundred and forty feet, which, without ventilation, was just as much out of the question as to tunnel a hundred and forty miles.