about Eradicate?"

Tom smiled.

"Rad would get homesick for his mule Boomerang, and I'd have to bring
him back just when we'd found the diamonds," replied the young inventor.
"No, we'll have to think of some one else. I'll ask Mr. Damon, and then
I'll consider matters further. I expect to see Mr. Jenks to-night, and
he may have some one in mind."

"Perhaps that will be a good plan. Well, Tom, I trust you will take good
care of yourself, and not run into unnecessary danger. Is the Red Cloud
in good shape for the voyage?"

"It needs looking over. I'm going to get right at it."

"It's a pretty indefinite sort of a quest you're going on, Tom, my son.
How do you expect to find Phantom Mountain?"

"Well, it's going to be quite a task. In the first place we'll head for
Leadville, Colorado, and then we'll go to Indian Ridge and make some
inquiries. We may get on the track of the place that way. If we don't,
why I'll take the airship up as high as is necessary and sort of
prospect until we see that big cliff that's shaped like a head. That
will give us something to go by."

"Well, do the best you can. If you can discover the secret of making
diamonds it will be a valuable one."

"I guess it will, dad; and Mr. Jenks is entitled to know it, for he paid
his good money to that end. He has promised to go halves with me, as
payment for the use of the airship, and I must say the two diamonds he
gave me last night have proved very valuable."

"Two diamonds, Tom? You only showed me one, an uncut gem;" and Mr. Swift
looked at his son.

"Oh, the other--er--the other is--I left it with a jeweler," and Tom
blushed a trifle, as he thought of the present he contemplated making to
Mary Nestor.

That afternoon, as Tom was out in the shed of the Red Cloud looking over
the airship, to see what would be necessary to do to it in order to get
it in shape for a long trip, he heard voices outside.

"Yes--yes, I know the way in perfectly well," he caught. "You needn't
bother to come, my good fellow. Just step this way, and I'll show you
something worth seeing."

"I wonder if it's that mysterious man coming back?" thought Tom. He
dropped the tool he was using, and hurried to the door. As he approached
it he heard the voice continue.

"Why bless my shoe laces, Mr. Parker! You'll see a wonderful airship, I
promise you. Wonderful! Bless my hatband, but I hope Tom is here!"

"Mr. Damon!" exclaimed our hero, as he recognized the tones of h