"Keep it up!" advised George. "That sounds exactly like a beaver's tail connecting with the surface of a stream!"
"Yes, keep it up!" cried a voice out of the darkness. "Keep it up, and perhaps some beaver'll come along and build a dam to get you out of that mess you're in! You're always getting into trouble, you two!"
"You've got your nerve with you!" exclaimed Will, half-angrily. "Here you go out in the night and get lost, and we come out after you, and the mine gets flooded, and we get tied up between the the solid wall and a bend in the passage, and then you blame us for getting into trouble!"
"Can you climb?" chuckled Tommy, throwing the rays of his searchlight on the boat. "If you can, just mount up on that pile of shale and work your way through the opening between the two levels. This might have been used as a sort of an air hole a few hundred years ago," he went on, "but I'll bet that not one out of a hundred of the miners of today know that there is an opening here!"
Leaving the boat, the boys mounted the pile of shale and were soon making their way up the rugged face of the shaft in the direction of the level, which ran along above the one now being flooded.
"Can you find your way out of this dump, now?" asked Will as the boys stood with their chums at the end of a long passage.
Chapter VII
A TREACHEROUS FOE
"There seems to be fewer twists and turns in this level than on the one below it," Tommy explained, "and I guess we can find our way out readily enough. If we don't," he went on, "I shall be obliged to eat a ton or two of coal to keep from starving to death."