"But it wouldn't make any difference, Frank, seeing that we couldn't get away from here, even if we wanted to just now," remarked Bob.
"That's so," returned his chum; "just as Nick said; we're here, and we've just got to stick it out, no matter what comes."
"But do you take any stock in what Peg said about an avalanche?" asked Bob.
"Mighty little," Frank replied. "This mountain is made up mostly of solid rock. That's what makes lots of people believe in the volcano idea. A slide would be hard to start here, and it just couldn't carry much along with It. Where mountains have sides made up of earth and loose rocks, that happens sometimes."
"I'm glad to hear that," remarked the other. "But there comes another shake. Whew! feel how she trembles, Frank! Whatever sort of power can it be that makes this noise and shivering sensation?"
Frank waited until the convulsion had passed before replying.
"I've got a strong suspicion, Bob," He said, finally; "and it's something that came into my mind since feeling the sound, for that's the only way I can express it. Now, what does it make you think of, most of all?"
"I did think it was thunder," declared Bob; "but now it seems to me the only thing I can compare it to is the beating of the terrible billows against the coast away up in Maine, when a fierce northeast storm is blowing. They seemed to make the rocks quiver just as this does now."
If Frank had intended to reply to this remark he was prevented by something unexpected that happened just then. This time it was not the furious roar of the unknown force within the mountain that disturbed him; but a cry that rang out shrilly.
"Help! Help!"