l conclusion.

"Well, if we don't find the platinum mine we'll rescue your brother, if
there's a possible chance!" exclaimed Tom one day, as he sat in the
pilot house with the exile. "Jove! it will be great to drop down, pick
him up, and fly away with him before those Cossacks, or whoever has
him, know what's up."

"I'm afraid we can't make such a sensational rescue as that," replied
Mr. Petrofsky. "We'll have to go at it diplomatically. That's the only
way to get an exile out of Siberia. We must get word to him somehow,
after we locate him, that we are waiting to help him, and then we can
plan for his escape. Poor Peter! I do hope we can find him, for if he
is in the salt or sulphur mines it is a living death!" and he shuddered
at the memory of his own exile.

"How do you expect to get definite information as to where he might
be?" asked Tom.

"I think the only thing to do is to get in touch with some of the
revolutionists," answered the Russian. "They have ways and means of
finding out even state secrets. I think our best plan will be to land
near some small town, when we get to the edge of Siberia. If we can
conceal the airship, so much the better. Then I can disguise myself and
go to the village."

"Will it be safe?" inquired the young inventor.

"I'll have to take that chance. It's the only way, as I am the only one
in our party who can speak Russian."

"That's right," admitted Tom with a laugh. "I'm afraid I could never
master that tongue. It's as hard as Chinese."

"Not quite," replied his friend, "but it is not an easy language for an
American."

They talked at some length, and then Tom noticing, by one of the
automatic gages on the wall of the pilot house, that some of the
machinery needed attention, went to attend to it.

He was rather surprised, on emerging from the motor compartment, to see
Mr. Damon standing on the open after deck of the Falcon gazing
earnestly toward the rear.

"Star-gazing in the day time?" asked Tom with a laugh.

"Bless my individuality!" exclaimed the odd man. "How you startled me,
Tom! No, I'm not looking at stars, but I've been noticing a black speck
in the sky for some time, and I was wondering whether it was my
eyesight, or whether it really is something."

"Where is it?"

"Straight to the rear," answered Mr. Damon, "and it seems to be about a
mile up. It's been hanging in the same place this ten minutes."

"Oh, I see," spoke Tom, when the speck had been pointed