Anything was better than being left alone in the dark, cavernous room, and Dean followed the negro, who was so short that he could readily look over his head, till at the end of the passage he emerged into another apartment, which was fitted up as a kitchen, and contained a stove. From the stove rose an upright funnel, which pierced the roof, providing a vent for the smoke when there was a fire, and allowing air to come in from above. It flashed upon Dean that it was through this funnel had come the mysterious sounds which puzzled him so much when he was reclining in the wood. CHAPTER XXXI. THE VALUE OF A HARMONICA. About the middle of the forenoon Pompey curled up on a pallet in one corner of the room, and went to sleep. There was nothing in particular to do, and it seemed rather a sensible way of spending the time. Dean, however, felt too anxious to follow his example. It occurred to him that it would be a good time for him to gratify his curiosity by examining the cavern in which he was immured, and devise, if possible, some method of escape. First he went up close to Pompey, and examined him carefully to see whether he was really asleep, or only shamming. But the negro's deep breathing soon satisfied him that there was no sham about his slumber. So Dean felt at liberty to begin his exploration. He went back to the entrance, which he knew by the staircase he had descended with Kirby and Dan. He mounted to the top, and found his way barred by a trap-door which he tried, but unsuccessfully, to raise. It appeared to be secured by a lock, and, not having the key, there was no hope of escape. He gazed ruefully at this door, which shut him out from liberty. "I wonder if there is any other way out of the cave," he asked himself. It didn't seem probable, but it was of course possible, and worth while to investigate. If there were it would be at the other end, no doubt. He retraced his steps, and found Pompey still fast asleep, and utterly unconscious of the movements of the prisoner under his charge. Dean took a lamp and went farther into the cave. There seemed to be a series of excavations, connected by narrow passages. In one of these was a large box, constructed like a sailor's chest. It occurred to him that it might belong to Pompey, and be used by him to contain his clothing. But a little thought suggested that the negro was not likely to have a large stock of clothes. Probably the suit he had on was about all he possessed. What, then, did the chest contain? At each end was a handle. Dean took hold of one and tried to lift the chest. But he found it very heavy, much heavier than it would have been had it contained clothing. He rose to his feet and eyed it with curiosity. There was nothing elaborate about the lock, and it struck Dean that a key which he had in his pocket might possibly unlock it. Upon the impulse of the moment he kneeled down and inserted it in the lock.