I had never thought of such a thing! I had often seen the work of frost on stones, but to take advantage of nature in this manner never occurred to me.
Eagerly and cautiously I set to work with my little steel pick, to drill what holes I might before Bishop came. But it was heart-breaking labour, and so slow that at the end of a week I had not loosened a single bar.
The next week the weather was bitterly cold. I had drilled some few holes around the base of an iron stanchion, and now I filled them with water and plugged them with a paste of earth from beneath my flooring, threads from my towel, and some soap.
At dawn I was at my window, and to my delight found the stone cracked; but the iron bar was as firm as ever, so I set to drilling my holes deeper.
At the end of that week Dulcima let me know that Jack had loosened one bar of his window, and could take it from its socket whenever I was ready. So I worked like a madman at my bar, and by night was ready to charge the holes with water.
It was now the middle of March; a month only remained to us in which to accomplish our liberty, if we were to escape at all.
That night I lay awake, rising constantly to examine my work, but to my despair the weather had slowly changed, and a warm thaw set in, with rain and the glimmer of distant lightning. In vain I worked at my bar; I could see the dark sky brighten with lightning; presently the low mutter of thunder followed. An hour later the rain fell hissing into the melting snow in the prison yard.
I sent word to Mount that I could not move my bar, but that he must not wait for me if he could escape from the window. He answered that he would not stir a peg unless I could; and the girl choked as she delivered the message, imploring me to hasten and loose the bar.
I could not do it; day after day I filled the cracks and holes, waiting for freezing weather. It rained, rained, rained.
Weeks before, Mount had sent the girl to seek out Mr. Foxcroft and tell him of my plight. I also had sent by her a note to Silver Heels.