But luckily Peggy's childish strength was not put to the test, for Bobby accomplished the crossing in safety, and scrambled over the rocks which rose at the other side. Holding up the lantern, the children found they were in what seemed to be the entrance of a rough kind of passage. That it was not altogether of natural origin was evident from the traces of built-up stones, while here and there the walls showed the marks of the pick. The air was stale and damp and difficult to breathe, and the candle burnt so badly that several times Peggy feared it was going out altogether. They went stumbling along over the irregular floor, wondering whether their way was taking them to safety, or only into the bowels of the earth.