The boy promised to heed their warnings, and began firing up again. The tank was completely filled with water, and the wagon filled nearly full of wood, so that the two were capable of running the contrivance for the entire day, provided there was no cessation, and that he was on the 'go' continually. Before starting, it was thoroughly oiled through and through, and put in the best possible condition, and then waving them all a pleasant farewell, he steamed gayly toward the mountains. The ground was admirable, and the steam man traveled better than ever. Like a locomotive, he seemed to have acquired a certain smoothness and steadiness of motion, from the exercise he had already had, and the sharp eye of the boy detected it at once. He saw that he had been very fortunate indeed in constructing his wonderful invention, as it was impossible for any human skill to give it any better movement than it now possessed. The first three or four miles were passed at a rattling gait, and the boy was sitting on the front of his wagon, dreamily watching the play of the huge engine, when it suddenly paused, and with such abruptness that he was thrown forward from his seat, with violence, falling directly between the legs of the monster, which seemed to stand perfectly motionless, like the intelligent elephant that is fearful of stirring a limb, lest he might crush his master lying beneath him. The boy knew at once that some accident had happened, and unmindful of the severe scratch he had received, he instantly clambered to his feet, and began examining the machinery, first taking the precaution to give vent to the surplus steam, which was rapidly gathering. It was some time before he could discover the cause of difficulty, but he finally ascertained that a small bolt had slipped loose, and had caught in such a manner as to check the motion of the engine on the instant. Fortunately no permanent injury was done, and while he was making matters right, he recollected that in chatting with the trapper as he was on the point of starting, he had begun to screw on the bolt, when his attention had been momentarily diverted, when it escaped his mind altogether, so that he alone was to blame for the accident, which had so narrowly escaped proving a serious one. Making sure that everything was right, he remounted the wagon, and cautiously resumed his journey, going very slowly at first, so as to watch the play of the engine. Everything moved with its usual smoothness, and lifting his gaze he descried three buffaloes, standing with erect heads, staring wonderingly at him. 'If you want a chase you may have it!' exclaimed the boy as he headed toward them. CHAPTER XI. THE STEAM MAN ON A BUFFALO HUNT. WITH A WILD snort of alarm, the three buffaloes turned tail and dashed over the prairie, with the shrieking steam man in pursuit.