Mayhew figured that they would be able to reach the spot he had picked out for a stand, if nothing happened to upset his plans. Once there, if they poured a deadly volley in among their pursuers, and followed that up with a second from their small arms, the Indians might become demoralized. It might have worked as he hoped, but the chances were that the Indians would have immediately dodged, and in this way escaped the full effect of the bombardment. Then, when the firearms were empty, they would push their advantage, and numbers must surely tell. The yells were still rising discordantly behind them, when Dick began to notice a decided change to their intonation. What had before seemed only an outbreak of savage rage now had turned to wonder, and even deadly fear. [Illustration: "BEFORE THEM THEY SAW A MIGHTY COLUMN OF STEAMING WATER"] There was also something else that caused the boy to turn his head, in order to cast a backward look. No sooner had he done this than Dick came to a full stop, his loud shouts attracting the attention of his two companions, and causing them to copy his example. No longer were the eager Indian braves chasing madly after their intended quarry; on the contrary, each and every warrior seemed bent on running like mad in the opposite direction, as though pursued by a legion of evil spirits. To the whites there was no mystery in regard to the fright of the ignorant and superstitious Blackfoot braves, for before them they saw a mighty column of steaming water gushing fully a hundred feet up into the air, to descend in an imposing flood. As if an unseen hand had directed it, the giant geyser had spouted just in time to come between the hostile Indians and their intended victims! CHAPTER XIII DEEPER INTO THE WONDERLAND "OH! it must all be true, Dick!" These words burst from Roger's lips as he stood gazing at the wonderful sight. Of course he referred to the strange tales which they had heard from some of the Mandans, and which also passed current among the frontiersmen connected with the expedition. Dick was hardly less staggered than his cousin, and, as for Mayhew, he had the look of one who believed himself face to face with the spirit world. As they shrank back and watched the amazing fountain pour its flood toward the sky, and heard the thunder of the falling water, strange thoughts flitted through their minds. "Look, Dick, it's slackening now!" cried Roger, presently, though he had to exercise his vocal cords considerably in order to make himself heard above the tumult of the gushing geyser. "Yes, I believe it is about to stop!" echoed the other boy, not without perceptible relief in his tones. All at once they realized that the flow of steaming water had ended as abruptly as it had begun. The pool was still agitated at the spot where the base of the pillar of water had been located, but the terrible geyser had ceased to flow. (Note 3.)