ur chance," his chum called.

As before, the grumbling began with an earth tremor. It was as though
some giant, whose mighty limbs were shackled, was trying to break
loose; and in so doing made things near him tremble.

Rapidly the noise increased, until it became terrifying. Bob had
dropped flat, and cowered there, almost holding his breath with awe.
Not so Frank, in whose care was the burning torch.

He had whipped off his coat at the first sign of the disturbance. This
he hastily arranged so as to partially protect the burning brand. Of
course in such a violent draught the suction was enough to make the
flame flare and flicker until at one time Frank feared it could not
stand the struggle. But just as he was ready to give up the attempt,
the furious wind seemed to slacken.

Bob raised his head to see the torch still burning, and it soon
recovered its full capacity for illumination.

"Bully!" he exclaimed, beginning to rise from his position of hugging
the rocky floor of the cave; "you did it that time, Frank. But hurry
up, and get your coat on. Gee! but this air feels chilly in here, and
damp too!"

Frank had found that out for himself. He was even shivering; and made
haste to don his jacket.

"Now let's be moving while we have the chance," he said. "I hope that
before the next rush comes we'll sight what we're looking for."

Perhaps his sharp eyes had discovered certain signs that told him they
were near the working part of the cave. Men cannot mine a lode of
precious ore without leaving many traces behind to tell of their
presence. And the stream of clear water that passed across the place
seemed to offer a splendid chance for panning any golden treasure that
might be found in the shape of soft quartz.

Now and again Frank would place the torch behind him. Bob wondered
what he did this for until he saw his chum bending his head forward as
though endeavoring to discover what lay ahead. Then he realized that
the light blinded him while it was before his eyes, and he sought to
avoid the trouble in this way.

"There's another bend ahead, Bob," Frank remarked, presently.

"Yes?" said the Kentucky lad, eagerly, suspecting what was coming.

"And I can see signs of light at the curve," Frank went on.

"Hurrah! Everything seems to be coming out just as you figured, Frank.
When I get back to the ranch I'm going to write to the president,
proposing that he put you in charge of the weather bureau.