"It does rather look that way," answered the mine boss, "but I'd rather risk it, under the circumstances, than face those fellows just now. They have had a chance to recover from their surprise at our appearance, and some of them are as mad as hornets to think they let us go. A moment's hesitation when we opened that door and found ourselves among them would probably have cost us our lives. Our very boldness was all that saved us. A danger boldly faced is robbed of half its terrors. "By-the-way, Derrick, our coming on those fellows as we did was a most remarkable thing. I thought your tracing was leading us to the top of the air-shaft instead of to the chamber at its bottom. We must be on a lower level than we thought. How do you account for it? Can you have made a mistake in regard to the plans?" Derrick's heart sank within him as he remembered the weak spot in his tracing; but he answered, "I don't think so, sir; though it does look as if something was wrong." Here conversation was interrupted by the difficulties of the road, for they had reached the mass of fallen debris that blocked Job Taskar's way a little later. As they crawled on hands and knees over the obstruction, the mine boss said, hoarsely, and with great difficulty, "Hurry, boy! there's gas enough here to kill us if we breathe it many minutes. If we had naked lights instead of safeties we'd be blown into eternity." After they had safely passed this danger he said, "I hope with all my heart that those fellows won't come that way looking for us; there's sure to be an explosion if they do. I don't believe they will, though," he added, after a moment's reflection; "they're too old hands to expose themselves needlessly to the fire-damp." They had again waded through the icy water, which the mine boss said he must have drawn off before it increased so as to be dangerous, and were well along towards the opening into the break, when the muffled sound of the explosion reached their ears. "There's trouble back there!" exclaimed Mr. Jones, as he relighted their lamps, which the rush of air had extinguished, "and I'm afraid that somebody has got hurt. You go on out, Derrick, and I'll go back and see. No, I won't, either. I can get there as quickly, and do more good, by going round outside and down the slope. Come, let us run." In a few minutes they had reached the bottom of the break, climbed the rickety ladder, and once more they stood in safety beneath the starlit sky of the outer world. "Eight o'clock," said Mr. Jones, looking at his watch. "We've been in there three hours, Derrick, and seen some pretty lively times. What I can't understand, though, is how we got in on that lower level. Never mind now; we must run, for I'm anxious about that explosion."