oard, and they expected to
start the next morning. In order to make sure that any stones which they
might succeed in getting from the diamond makers were real gems, a set
of testing apparatus was taken along. Mr. Parker had had some experience
in this line, and, in spite of the fact that he might make direful
predictions, Tom was rather glad, after all, that the scientist was
going to accompany them.

"But what is worrying me," said Mr. Damon, "is what we are going to do
after we get to Phantom Mountain. What are your plans, Mr. Jenks? Will
you go in, and demand your share of the diamond-making business?"

"I have a right to it, as I invested a large sum in it, and I am
entitled to more than a half-share. But, of course, I can't say what
I'll do until I get there. We may have to act very secretly."

"I'm inclined to think we will," said Tom. "My plan would be to gain
access to the cave, if possible, and watch them at work. We might be
able to discover the secret of making diamonds, and, after all, that's
what you want, isn't it, Mr. Jenks?"

"Yes, I paid my money for the secret, and I ought to have it. If I can
get it quietly, so much the better. If not, I'll fight for my rights!"
and he looked very determined.

"Bless my powder horn!" cried Mr. Damon. "That's the way to talk! And
so we're to go cruising about in the air, looking for a mountain shaped
like a man's head."

"That's it," a greed Mr. Jenks, "and when we find it we will be near
Phantom Mountain, and the diamond makers."

The final details were completed that night. The last of the supplies
had been put aboard, the larder was well stocked, the diamond testing
apparatus was stored safely away, and all that remained was for the
adventurers to board the Red Cloud in the morning, and soar away.

That night Tom was uneasy. Several times he got up, and looked toward
the shed where the airship was stored. He could not rid himself of
the idea that the men to whose interest it was that the diamond-making
secret remain undiscovered, might attempt to wreck the airship before
the start. Consequently both Eradicate Sampson and Engineer Jackson were
on guard. Tom looked from his window, to the shed where the Red Cloud
was housed. He saw nothing to cause him any uneasiness.

"I guess I'm just nervous," he mused. "But, all the same, I'll be glad
when we've started."

They were all up early the next morning, Mr. Damon beginning the day by
blessing the sunrise, and