aculated half aloud. "It's from Abe Abercrombie, that
miner I met when we were after the diamond-makers! He says he is on
his way east to get ready to start on the quest for the Alaskan
valley of gold, in the caves of ice. I had almost forgotten that I
promised to make the attempt in the big airship. How did this letter
come, Mrs. Baggert?" he asked.

"By special delivery. The messenger brought it a few minutes ago."

"Then we may see Abe any day now. Guess I'd better be looking over
the RED CLOUD to see if it's in shape for a trip to the Arctic
regions."

Tom's attention for the moment was taken off his little monoplane,
and his memory went back to the strange scenes in which he and his
friends had recently played a part, in searching for the cave of the
diamond-makers on Phantom Mountain. He recalled the promise he had
made to the old miner.

"I wonder if he expects us to start for Alaska with winter coming
on?" thought Tom.

His musings were suddenly interrupted by the entrance into the yard,
surrounding the aeroplane shed, of a lad about his own age.

"Hello, Ned Newton!" called Tom, heartily.

"Hello, yourself," responded Ned. "I've got a day off from the bank,
and I thought I'd come over and see you. Say, have you heard the
latest?"

"No. What is it?"

"Andy Foger is building an airship."

"Andy Foger building an airship?"

"Yes, he says it will beat yours."

"Humph! It will, eh? Well, Andy can do as he pleases as long as he
doesn't bother me. I won't be around here much longer, anyhow."

"Why not, Tom?"

"Because I soon expect to start for the far north on a strange
quest. Come on in the shed, and I'll tell you about it. We're going
to try to locate a valley of gold, and I guess Andy Foger won't
follow me there, even if he does build an airship."

Tom and his chum started toward the shed, the young inventor still
holding the letter that was to play such an important part in his
life within the next few months. And, had he only known it, the
building of Andy Foger's airship was destined to be fraught with
much danger to our hero.

CHAPTER II

ANDY FOGER'S TRIPLANE

"Going to look for a valley of gold, eh?" remarked Ned Newton as he
and Tom took seats in a little room, fitted up like a den, where the
young inventor frequently worked out the details of the problems
that confronted him. "Where is this valley, Tom? Anywhere so I could
have a chance at it?"

"It's up in Alaska. Just