now. If this is the landmark
Mr. Jenks was searching for, then we must be in the vicinity of Phantom
Mountain."

"I think we are," declared the diamond seeker. "Probably it is within
sight now, but there are so many peaks, and this is such a wild and
desolate part of the country that we may have trouble in locating it."

"We've got to make a beginning, anyhow," decided Tom, "and the sooner
the better. Come, we'll make up our camping kits, and start out."

It was something to know that they were on the right trail, and it was a
relief to be able to busy oneself, and not be aimlessly searching for a
mysterious landmark. They all felt this, and soon the airship was taken
to a secluded part of the valley, where it was well hidden from sight in
a grove of trees.

Tom and Mr. Damon then served a good meal, and preparations were made
to start on their search among the mountains--a search which they hoped
would lead them to Phantom Mountain, and the cave of the diamond makers.

The tent which would afford them shelter was in sections, and could
be laced together. They carried food, compressed into small packages,
coffee, a few cooking utensils; and each one had a gun, Tom carrying a
combination rifle and shotgun, for game.

"We can't live very high while we're on the trail," said the young
inventor, "but it won't be much worse than it was on Earthquake Island.
Are we all ready?"

"I guess so," answered Mr. Damon. "How long are we going to be away?"

"Until we find the diamond makers!" declared Tom, firmly.

Shouldering their packs, the adventurers started off. Tom turned for a
last look at his airship, dimly seen amid the trees. Would he ever come
back to the Red Cloud? Would she be there when he did return? Would
their quest be successful? These questions the lad asked himself, as he
followed his companions along the rocky trail.

"Perhaps we can find the road by which these men go in and out of the
cave," suggested Mr. Damon, when they had gone on for several miles.

"I fancy not," replied Mr. Jenks. "They probably take great pains to
hide it. I think though, that our best plan will be to go here and
there, looking for the entrance to the cave. I believe I would remember
the place."

"But why can't you follow the directions given by the miner who told you
about Phantom Mountain?" asked Mr. Damon.

"Because his talk was too indefinite," answered Mr. Jenks. "He was so
frightened by seeing what he believed to be a