"Steady," gasped Atherton, as his feet came in contact with the water. "Wade through it." He was hoping against hope. His practical eye had already noted that the water extended far beyond the limits of the little puddle they had encountered in the lowest level of the dip. This meant that there might be five feet or more of water in the tunnel, or there might be sufficient space between the surface and the top of the vaulting to enable the lads to proceed. "What's happened, I wonder?" asked Green, who, like the other, was knee-deep in water. "Don't worry: keep on," enjoined the Leader. "There's no current, luckily, but let's hang on to one another in case there's a pitfall. Keep the spare pieces of candle dry, Mayne, whatever you do. I've put the matches in my hat." Waist deep now. The rate of progress was visibly retarded by the resistance of the water. Peering ahead, Atherton could see that at less than twenty yards from where he stood the roof of the tunnel met and dipped below the surface of the newly formed lake. The Scouts were trapped. "No go, lads," announced Atherton, in a cheerful tone. "We must get back to the higher level. It must be raining pretty heavily, and the water soaks through." "A jolly good soak, I should say," added Green. "What do you propose doing now, Atherton?" "Exercise patience, and have another shot at that revolving stone. It's merely a question of time and an element of luck. Besides, when the water begins to subside it will do so pretty rapidly, I expect." "Why?" asked Green. "I don't know why, unless the floor of the tunnel is very porous. Don't you remember that within twenty hours of the time that Tassh was unable to leave Seal Island he was back again by means of this passage?" "That's so," agreed Green, stooping to wring the moisture out of his shorts. "How's the candle going, Atherton?" "It will last us a bit," replied the Leader; but he knew that in less than an hour at the outside their whole supply of candle ends would be consumed. "Let's shout altogether," suggested Mayne, after they had returned to the top of the spiral staircase and had made another unsuccessful attempt to discover the secret of the mechanism of the revolving stone. The Scouts gave a united yell. The echoes rang in their ears, but no answering sound came from the other side of the baffling granite wall. "Look here, you fellows," said Atherton, "it's no use our waiting here on the off chance of some one opening the door or whatever you call it, from the inside. One of us ought to stand by and watch for the water to subside. Who's game?" "It will mean that one of us will have to be in the dark," observed Mayne gloomily. "I'm not frightened of the dark, of course, but it's pretty miserable sticking about by yourself in a pitch-black hole." "That's so," agreed Green. "I vote we all keep together."