His meditations, however, were interrupted by the report of a gun in the distance and the faint sound of a shout that came across the sands. Glancing hastily in the direction from which the hail had come, Reuben saw that soon after his friend had appeared to join in the chase the black horse had swerved in his course and instead of continuing on his way had turned backward and now was directly approaching the place where Reuben was standing. And still the horse was running easily and apparently without fatigue. To overtake him seemed almost a hopeless undertaking. Again Reuben assured himself that never before had he seen such strength combined with swiftness and grace. Aware, however, that he must do something now to help, Reuben leaped upon the back of his tired horse and urged it once more to join in the pursuit. A challenging neigh now came from the swiftly running black horse, and almost as if he ignored the puny efforts of his foes to overtake him, the course he was following again was changed and with a sudden burst of speed the animal, like a thunder-bolt, dashed past the place where Reuben was standing. The young trapper now joined in the shouts and he, too, discharged his gun as a warning to Kit Carson, who was doubtless waiting at the place where he had abandoned the chase. The efforts, however, were useless, as in a brief time once more, swiftly swerving to his left, the black horse dashed into what at first seemed to Reuben to be an unbroken mass of rocks. In an instant the animal had disappeared from sight. As rapidly as his horse was able to bear him, Reuben rode to the place where the leader had so strangely disappeared. As he came near he discovered a narrow opening or gorge apparently caused by some great crack in the formations centuries before. As Reuben entered the narrow place he saw eight or ten feet below him a stretch of more level land, though it was dotted here and there with stones and boulders. It seemed impossible to the young scout that a horse could have leaped to the ground below. However, at that moment he heard the sound of a defiant neigh and in a brief time was able to discern the outline of the form of the black horse speeding along a narrow trail which was at least twenty-five feet above the plain on which he was riding. It was plain that the horse was familiar with every foot of the region. Along this narrow ledge the black horse now was running with confidence unbroken, although the pathway was not more than a yard wide. Indeed in several places it seemed to the astonished Reuben that the width was still less.