"As we progressed in our work we experienced great difficulty from the want of pure air to breathe, and to sustain our candles, which refused to burn. Consequently, one of our party was compelled to stand at the opening, fanning pure air into the tunnel with his hat. Our atmospheric difficulties were the more increased by the small size of the hole, which was a little less than two feet in diameter, quite irregular in consequence of large stones, and descended in a line below the horizontal. This severe labor was carried on without much interruption for more than three weeks, when, at last, the plan came near being a failure on account of a sad mistake in our measurement. Our intention was to reach the yard of an old shed, or warehouse, in which were then stored the boxes sent us by the Christian and Sanitary Commissions, and by our friends at the North. "Thinking we had reached the desired point, an opening was made to the surface, when it was found we were still in the street, outside the fence, and within a few yards of the sentries. Not discovered by this mishap, the hole was quickly filled with a pair of old pants and some straw, and the work of excavation continued to the spot intended. "The selection of this point was very fortunate, as the guards used to skulk about this building at night for the purpose of plundering the boxes, and on the night of the escape, as it happened, they saw every man that came out; but, supposing them to be friends, only whispered to each other, that 'the boys were going through the _Yankee boxes_ mighty fast.' "These whisperings," adds Captain Glazier, "were distinctly heard by some of our men. The tunnel was about sixty-five feet in length, and was ready for use February ninth, 1864. "The company of diggers had arranged that they should make their egress first, and inform the others just as they were going out. But each man had a particular friend whom he wished to notify, and, as we were seen packing our clothing, it soon became suspected among our fellow-prisoners that something unusual was in the wind. Curiosity, once on the alert, soon discovered the secret, and then all were jubilant with the hope of escape, and forthwith commenced packing their poor wardrobes. But egress was so slow that it soon became evident to the cool calculator that, at best, but a comparatively small proportion of our number would be fortunate enough to take their departure from 'Libby' before daylight would forbid any further efforts in that direction.