"Guess it doesn't work any more," he said in a low tone.
"Twist it!" cried Ned. "Twist it like a door knob."
In a flash Tom did so. For a moment no result was apparent, then, from somewhere far off, there sounded a low rumble, above the roar of the black stream.
"Something happened!" cried Mr. Damon.
"Back to the river!" shouted Tom, for they were some distance away from it now. "If it's rising we may have a chance to escape."
They hurried to the edge of the stone channel, and Ned uttered a cry of delight.
"It's going down!" he yelled, capering about. "Now we can go on!"
And, surely enough, the river was falling rapidly. It no longer roared, and it was flowing more slowly.
"The water is shut off," remarked Tom.
"Yes, and see, there are steps which lead across the channel," spoke Ned, pointing to them as the receding water revealed them. "Everything is coming our way now."
In a short time the water was all out of the channel, and they could see that it was about twenty feet deep. Truly it would have been a formidable stream to attempt to swim over, but
