"Sure," was the reply. "Say, it took my breath away at first, but it's all right now. This is going some!"
Faster and faster the boys were whirled along. The water was beginning to chill them now, and they were wet through. Once or twice a sudden change in the direction of the sluiceway nearly brought them to grief, and on one occasion Nat slipped off his plank. It was floating away from him, but his cry warned Jack, who managed to stop it, while Nat struggled forward, stooping to avoid the braces, and secured it again.
This occurred in a comparatively level place, where the current, after a quick descent, was not so rapid, otherwise there might have been a different ending to this story. For a mile farther the two boys floated along at an easy pace.
"I guess we've left 'em behind," Nat observed. He was riding his plank alongside of Jack now, as the flume was broad enough to permit this.
"Yes, but they're not going to give up so easily," Jack rejoined. "There's too much at stake. They'll chase us, but it's another thing to catch us. Hark! What's that?"
From down below in the moonlit valley, into which the flume dipped there came a roaring sound. It was like a mighty wind blowing, and, as the boys were carried on and on, it increased in intensity.
"Sounds like a waterfall," observed Nat.
"So it does. I hope this flume doesn't do any stunts like that. We'll be dashed to pieces."
"Maybe we'd better stop now, and get out," said Nat. "I wonder where we are?"
"Haven't the least idea. We must have come about three miles though.
Let's see if we can stop ourselves,"