He and his cousins rode their horses up the rather steep and winding trail that led from the bottom of the reservoir to the top, where a big iron pipe, sticking out under the mountain like the head of some great serpent, brought from the distant Pocut River a stream, without which it would have been impossible to raise cattle in the valley the boy ranchers claimed as particularly their own. "Who you reckon it is?" asked Nort, as his pony scrambled up between the animals of Dick and Bud. "Oh, some prowler that may have been rustling our grub while we were over at the round-up," was the answer. "They couldn't get any cattle, for there aren't any to get," observed Dick. This was true, as all the animals had been driven from Happy Valley over to Diamond X. Later such as were not shipped away, and many of the calves and mavericks would be returned to fatten up and grow in readiness for the spring tallying. "I don't just like this!" murmured Bud, as he again urged his pony forward. "Have your guns ready, fellows!" And while they are thus riding toward the place where a strange tunnel pierced Snake Mountain, I shall take this opportunity to present, more formally than I have yet had a chance to do, my new readers to the boy ranchers. For that is what Bud Merkel, and Nort and Dick Shannon called themselves, being that, in fact. Bud was a western lad, the son of Henry Merkel, who had been a ranchman all his mature years. He lived at Diamond X ranch, with his wife and daughter Nell. Some time before this present story opens Bud's cousins from the east had come to spend the summer with him, while their father and his wife made a trip to South America. Nort and Dick, though "tenderfeet" at the beginning, had quickly fallen into the ways of the west, and in the first volume of this series, "The Boy Ranchers," I was privileged to tell you how they helped solve a mystery that revolved around Diamond X. This mystery had to do with two college professors, and a strange, ancient animal. But it would not be fair to my new readers to disclose, here, all the secrets of that book. So successful was the first summer which Nort and Dick spent at their uncle's ranch, that they were allowed to repeat it the following season. But this time there was a change. As related in the second volume, "The Boy Ranchers in Camp," Mr. Merkel had, by utilizing an ancient underground water-course beneath Snake Mountain, and by making a dam in Pocut River, brought water to a distant valley he owned.