"Something like water running," replied Bud. "I have a notion that our stream--I call it ours for it doesn't seem to belong to anyone else--our stream may just trickle off, now and then, into some other underground course." "Maybe it does," agreed Dick. "But I don't hear any water running." "Nor I," added his brother. "Maybe I was mistaken," Bud admitted. "But I sure would like to come across that missing water of mine!" He little realized, nor did the others, what fruit his wish was to bear, and that very shortly. "I guess what you heard was the echoes," spoke Dick. "I never heard so many queer noises." "It's like the cave of the winds," murmured Nort. "But it's a great adventure all the same, Bud! I mean it would be great if we didn't have to worry about the water not coming back," he made haste to add, for he realized what it would mean to their new ranch in Flume Valley if no drink could be had for the cattle. "It beats the finding of the Triceratops all to slathers!" exclaimed Dick, "and that was no slouch of a happening, either." "Yes, no telling what's ahead of us," spoke Bud, as he walked along, unsteadily enough for the way was rough and filled with stones. And, as the boys tramped along in the tunnel, part of the time in the very bed of the stream that had gone dry, their lanterns cast fantastic shadows on the rocky walls. I have said that the stream was dry, but this was not strictly true, for in places, where the uneven bed formed depressions, there were pools of water. And, in some places, there were even little rills trickling along. But they never would reach the iron pipe that discharged into the reservoir. On and on tramped the boys, pausing, now and then, to hold up their lanterns and inspect the rocky walls of the underground tunnel which echoed so strangely to their footsteps, and through which swept strange, cold and clammy winds. "Well, I reckon we'll have to go all the way to the end before we discover anything, if we do find it," said Bud, when they had walked on for over an hour. Their pace was slow because of the uneven footing. "And when we get to the other end and find the water running into the pipe at the dam in Pocut River, what then?" asked Nort. "We'll hardly find that, I think," said Bud. "Or, I mean, we won't have to go all the way to the other end if the water is found running there." "Why not?" asked Dick. "Because, if the water's running in from the dam end of the pipe, we'll meet the stream before we get all the way through the tunnel," Bud explained. "I meant to call up on the telephone and find out if everything was all right at the river end before we started out, but I forgot. My theory is that the stream gets into this tunnel from the river all right, but is shunted off before it reaches us," he added. "How shunted?" Dick wanted to know.