And in the light of the lanterns, the one Nort had carried being forever lost, it seemed they all could see the explanation for the apparently mysterious action of the underground stream; or, rather, it was an explanation of part of the mystery; for this was only the beginning. Beyond where they stood, in the direction of Pocut River, there flowed through the ancient channel a body of water larger than that which usually filled the underground course. This was accounted for, likely, by the fact that it had been stopped, or dammed, by some natural or artificial means, and had suddenly been released. Thus the channel was more fully filled than usual. But, as I have said, the water came up to the point where the members of the expedition then stood. From there it made a sudden turn to their right, as they stood facing the river end of the tunnel. And it was this sudden turn--this shift in the course of the underground stream--which prevented it from engulfing our friends. But it had engulfed Nort. "I see what happened--or, at least, part of it," spoke Bud while the others listened. "The waters were suddenly turned on again, or turned themselves on, and shot this way. Nort heard them and ran down here to jump across the stream-bed, which was then dry. But he must have fallen over the edge of this traverse ledge, or channel, as I nearly did, and down he went!" They looked, and agreed that this was very likely how it had taken place. "But can't we save him?" pleaded Dick. "I'm a good swimmer. Let me try to get him! Maybe he's lying down there--on the bottom!" He made as if to take off his coat, but Old Billee grabbed him by the arm. "You'd only go t' your death, boy!" said the old ranchman hoarsely. "It's bad enough--as it is!" "But what happened to Nort?" asked Dick, and there was a sob in his voice. "He must have been carried away--down that stream--wherever it goes," asserted Snake Purdee. "That's just the point, where does it go?" Dick asked. "Wait a minute," counseled Bud. "Let's see if we can reason this out." He paused to give it thought. "The way this stream is running now," he resumed, "wouldn't put any water into our reservoir, would it?" "No," answered Yellin' Kid, and for once his voice was softened. "Th' water is all being shunted down this passage--where Nort fell." "But," resumed Bud, "this passage has always been here. We didn't see it before, as we walked on the other side of the main channel. Then if this side channel has always been here, and we managed to get water through our pipe when it was here, it stands to reason that it must fill in time, enabling the water to run along here," and he indicated the regular channel that extended back of them out toward Flume Valley. "That's so!" cried Old Billee. "There's an end, or a bottom, t' this channel somewhere, and poor Nort can't be carried all the way through th' earth."