"It's a regular hide-and-seek game, this locating a mine among these rocks."
For a long time the three boys sat by themselves, talking about days at Oak Hall, and about the folks left at home and about those now traveling through Yellowstone Park. It seemed a long time since they had received letters.
"I suppose there are letters at the hotel in Butte," said Dave, with a little sigh.
"I'd give something to have them here," added Phil.
"If only I knew how dad was making out," murmured the senator's son. "I suppose he is waiting every day to hear from me!"
"I hope the folks in the Park are having a good time," said Dave, after a pause. "I suppose the main body of tourists have started for home by now."
"Yes, they went yesterday, according to the advertised plan," answered Phil.
"I've got an idea," said our hero, after another pause. "Do you see that hollow just below here? Well, we haven't looked around that much. Why not try it to-morrow?"
"Abe Blower and Mr. Dillon both seem to think the opening to the mine was above that, Dave," said Roger.
"True, but the landslide changed things, remember. We may now find an opening down
