"S-s-s-say!" sputtered Tubby, "I hope my horse doesn't stumble." Suddenly a voice close at hand struck in. It was one of the cow-punchers shouting to another. "Remember the last stampede, when Grizzly Sam was trampled?" "You bet I do. His pony's foot stuck in a gopher hole, and the whole stampede came lambasting on top of him." The boys began to look rather serious. Apparently they were off on a more dangerous errand than they had bargained for. It was too late to draw out now, however, and, anyhow, not one of them would, for this would have shown "the white feather." "Did you give the alarm to the rest of the boys?" asked Rob of Harry, after an interval of silence among the boys. "Yes. I only had time to call Simmons's place, but they'll get the others. Simmons's place is not far from the Graveyard Cliffs, and the boys will be there ahead of us, likely." "How about the others?" "They have to come from greater distances. They may not arrive till it's all over." It was impossible to see any of their surroundings in the thick cloud of dust. All about them, as far as the eye could penetrate the dense smother, were straining ponies and shouting cowboys. "How can we tell when we get to the place?" asked Tubby. "My father is riding up ahead," rejoined Harry; "that big bay of his can make two feet to a pony's one. He'll call a halt when we get there." In the meantime a rumor had been passed from mouth to mouth among the cow-punchers. Moquis had been seen near the far pasture the night before, and open accusations were made that the renegades had started the stampede so as to be able to make a feast off the dead cattle in case they swept over the cliffs. "Mr. Mayberry hasn't succeeded in rounding them up yet, then," said Rob. "No," rejoined Harry, "and I heard one of the punchers say yesterday that Indians for miles around are coming into the mountains. I guess they won't disperse till after the snake dance." Suddenly a wild yell from up in front caused them to halt. "Got there, I reckon," uttered one of the cowboys. As he spoke there was but one question in every mind. "Were they in time?" As the dust cloud settled, and they were able to make out their surroundings, the boys found that they had come to halt on a sort of plateau. Just beyond this was a sheer drop, as if a great hunk had been cut out of the ground. This drop--which was fully sixty feet deep,--formed the dreaded Graveyard Cliff, so called, although, as will be clear from our description, it was more properly a deep, narrow gulch. The distance across the yawning crack in the plateau--which was undoubtedly of volcanic origin--varied from a hundred feet or more to fifteen, and even less. A queerer place the boys had never seen. But they had little time to gaze about them. Blinky, who was one of the crowd of stampede arresters, gave a sudden shout as they came to a halt. "Hark!"