"Doesn't this sort of set you fellows back so you want to give up ranching?" Mr. Merkel asked his son and nephews. "Not a bit!" promptly answered Bud. "We're going to stick!" added Nort. "And find out what makes this water stop," contributed Dick. "We'll show up Hank Fisher, Del Pinzo and that other bunch of crooks, too!" "I don't see how Hank could have had anything to do with this water stoppage," said Mr. Merkel. "Of course it may develop that he hired Pocut Pete to infect our cattle, but even that is doubtful. Those fellows are pretty cute. Anyhow, Pocut Pete is where he can't do any harm for some time. He won't be tried until fall. "But it's my idea, boys, that this water stoppage is caused by some natural means. We are using an old underground river bed, you realize, and there may be what I'd call a 'hole' in it somewhere. The water that ought to come to you may drop down that hole." "But why doesn't it do it all the while?" asked Dick. "That's one of the mysteries," said his uncle, "one that you'll have to solve." "We went over it all before," spoke Bud, "and we couldn't see even a branch passage." "Well, some of the men are going with you this time," his father said. "They're more used to looking for signs than you fellows are, though I must say you've done fine, so far!" As Mr. Merkel had stated, it was decided to send several of the cowboys with Bud and his cousins on this expedition into the dark tunnel. Old Billee, Yellin' Kid and Snake Purdee would be of the party, which would thus consist of six. In this way, there being safety in numbers, it was hoped that accidents might be avoided, or, if they happened, there would be at hand help for the unfortunates. "If we could only take a boat," said Dick, when the preparations were almost completed, "it would be great!" "What could we do with a boat in that stream, which is hardly three feet wide in places?" asked his brother. A boat had been mentioned in the first excitement, however, but the idea was abandoned as impracticable. "Well, if the flood came, as suddenly as it did when we had to take refuge on the ledge, we could float out," answered Dick. "A boat to hold six men would be too big to carry," spoke Bud. "Even a folding canvas one wouldn't answer. But I know what we can do." "What?" asked Nort. "We can each take an inner automobile tire. Blown up, they are as good as life preservers, and with them fastened to us we can float and be carried along by the current, if a flood happens again." It was decided that this was a wise precaution to take, and from Diamond X some inner tubes were sent over--old ones that had outlived their usefulness on the car, but which still held air, and would, as Bud said, make excellent life preservers.