Their eyes were fixed on the debating crowd, and they were wondering what the next move of the Kachins would be, when they heard a low call behind them. Both whirled round at once, and saw that it was their companion who was attracting their attention. She was kneeling on the floor, and they ran to her at once. She knelt beside a large stone which was sunk three or four inches below its fellows and shook easily under the touch. "This is strange," said Jack. "We dried our meat and ate our meal just about here, and the stone was not out of its place then." "Perhaps our movements loosened it," replied his father. He spoke with the native woman for a little, then turned to his son. "It sank a moment back when she stepped on it," he said. "Just when she cried out. She feared she was going to fall through the floor." Jack knelt down and pressed heavily on the stone. It slid away from his hands, and, had he not grasped the edge of the hole quickly, he would have rolled after it The stone vanished, and was heard to land with a heavy ringing crash on stone below. "By Jove, I nearly went head first after it," said Jack. "It was as loose as possible. Where does this lead to?" Mr. Haydon knelt down and looked carefully around the sides of the square hole left in the floor. "It's a secret entrance to some place or other," he said. "See, Jack, the wooden bar on which this stone worked. It has rotted through, and the stone held its place, as you may say, by clinging to the neighbouring stones. But a slight weight was sufficient to start it moving." "What's underneath, I wonder?" murmured Jack. "Some chamber built in the thickness of the floor between this room and the vault below," replied his father. "We ought to have a look into this," remarked Jack. "We will," said his father; "but I hardly see how it will avail us. There might be a chance to make it useful if we could get the stone into place, but it is very heavy, and the machinery on which it worked has rotted away." Jack took a half-burned torch, whose flare had been quenched upon their regaining the room from the raid in which they had secured the buck, and relighted it. He held it as far into the darkness as he could, and the red light showed that a ladder, built of heavy beams of teak, ran downwards from the edge of the hole. Mr. Haydon sniffed cautiously. "The air doesn't smell bad," he remarked; "close and musty, but no mephitic vapours. I think we'll go down." Jack swung himself over the lip of the hole, dropped his feet on the stout ladder, and went down first, holding the torch before him, and his father followed. They found themselves in a low room of fair size, but not one-half as large as that above and below.