"Me, either," added his brother, and together they looked at the depression in the ground, filled with scalding hot water. At times it bubbled up, like some great kettle over a fire, and then the steam was as thick as the smoke at some camp fire when green wood is used. Again the spring was comparatively quiet. "I've seen 'em before," remarked Bud, "though I didn't know we had any so near Happy Valley. There's lots of 'em out in the Yellowstone Park region, and in other places, some not many miles from here." "Any volcanoes?" asked Nort. "Or geysers?" Dick queried. "Not that I know of," Bud answered. "You don't need volcanoes to make boiling springs, though I suppose the hot water must be boiled over some internal fire beneath the earth's surface. And these same fires do, sometimes, make volcanoes. "But I've never seen any volcanoes around here; have you, fellows?" and he appealed to the cowboys. "Not since I came up from Mexico," one answered. "I was close to one there. And I've seen Old Faithful, and some of the other geysers in the Yellowstone." "They put soap in some to make 'em spout, don't they?" asked Dick, who remembered to have read something to that effect. "So I've heard," the cowboy said, "though it isn't supposed to be done. It sort of wears out the geyser, I believe, though I don't know much about such things. Anyhow, I don't know of any around here, though I have seen a few boiling springs, farther to the south." "Yes, I have, too," Bud admitted. "Well, here's one, and she sure is hot," he added, as a sudden activity on the part of the phenomenon sent up another cloud of steam. "We could boil eggs there if we had any." "We brought some along," Dick said, "but they're hard-boiled already. No use doing the job over. Say, but this is interesting!" he added, as the spring suddenly spouted up a little way, almost like a miniature geyser. "It would be more interesting if we could get closer on the trail of that gang of cattle thieves, and take away our steers," said Bud. "I wonder if the poor animals hurried in here for water, and couldn't drink it because it was hot?" He recalled days of helping haze cattle on long trails, when the creatures were tormented by thirst, and he knew how they suffered. "There are a few signs that they've been in here," remarked Slim, as the party was gathered around the boiling spring. "But they aren't here now." "Not much use in us staying here, either," commented Bud, as he looked around on the bleak and cheerless prospect. Except for the boiling spring there was no sign of natural life. All about were great and small rocks, piles of shale and jagged stones, as though the place had been swept by a prehistoric fire. They were in one of the twists and turns of the rocky defile, and it was a rocky pass, with no trees or grass growing except near the top, and these appeared to be a sort of overgrowth from the grass and foliage growing down above.