Suddenly Jack pricked his ears and raised his head, emitting at the same time a slight whiff through his nostrils. No words could have said more plainly: "Beware, master! I have discovered something." The rider's natural supposition was that the danger, whatever it might be, was on the crest of the ridge he was approaching; but, when he shaded his eyes and peered forward, he was unable to detect anything at all. Enough light remained in the sky for him to use his excellent eyes to the best advantage, but nothing rewarded the scrutiny. Jack continued advancing, though his gait was now a slow walk, as if he expected his master to halt altogether; but the latter acted like the skilful railway engineer, who, seeing the danger signal ahead, continues creeping slowly toward it, ready to check his train on the instant it becomes necessary to do so. He allowed the pony to step tardily forward, while he strove to locate the point whence peril threatened. "What the mischief do you see, Jack?" he asked, in a half-impatient tone; "if I didn't know you never joked, I would believe you were trying some trick on me to get me to camp for the night." Once the horseman fancied he caught the faint outlines of a thin column of smoke climbing into the sky from the crest of the ridge, but closer study convinced him that he was wrong. If such a signal were kindled, it must be clear enough to be recognized from the farther elevation, which was more distant than the horseman. "I shall observe the vapor as soon as they," he thought, "for my eyes are as sharp--helloa! that beats the mischief!" At last Warren Starr learned what it was that had alarmed his pony. CHAPTER II. THE VOICELESS FRIEND. The keen eyes, instead of looking at the crest of the rocky ridge on his right, were now centred on the ground, where they detected a small dark speck swiftly approaching the horseman. At the first glance, the object suggested a cannon-ball rolling with great speed toward the pony, that was now standing still, with head erect, ears thrown forward, and the appearance of perplexed interest in the thing, whatever it might be. For a minute Warren Starr was unable to guess the meaning of the singular sight. Whatever its nature, it was evident that it was aiming to reach the rider with the least possible delay. The latter drew his Winchester around in front, so as to be ready to receive it, his first thought being that it was some Sioux stratagem designed to do him ill. But while he gazed, he discovered its identity; it was a dog, running as if its very life were at stake. The next instant young Starr perceived something protruding from the front part of its body, resembling the ornamental feather in an Indian's head-dress. "It is an arrow!" he exclaimed. "The poor creature is badly wounded, and is striving to reach me before he dies. By gracious, it's Bruno!" he added, as a closer approach enabled him to identify the creature. "He brings me some message."