u'll be saying things you
don't want to, Tom and not at all in keeping with your former silence."

"That's so," agreed the young inventor, with a sigh. "But if things go
right I'll not have to keep silent much longer. I may be able to tell
you everything."

"Don't tell me--tell Mary," advised his chum. "She feels your silence
more than I do. I know how such things are."

"Well, I'll be able to tell her, too," decided Tom. "That is, if Schwen
hasn't spoiled everything. Look here, Ned, these papers show he's been
in correspondence with Blakeson and Grinder."

"What about, Tom?"

"I can't tell. The letters are evidently written in code, and I can't
translate it offhand. But I'll make another attempt at it. And here's
one from a person who signs himself Walter Simpson, but the writing is
in German."

"Walter Simpson!" cried Ned. "That's my friend of the tree!"

"It is?" cried Tom. "Then things begin to fit themselves together.
Simpson is a spy, and he was probably trying to communicate with
Schwen. But the latter didn't get the information he wanted, or, if he
did get it, he wasn't able to pass it on to the man in the tree.
Eradicate nipped him just in time."

And, so it seemed, the colored man had done. By accident he had
discovered that Schwen had prevailed on one of the workmen in Shop 13
to change passes with him. This enabled the German spy to gain
admittance to the secret place, which Tom thought was so well guarded.
The man who let Schwen take the pass was in the game, too, it appeared,
and he was also placed under arrest. But he was a mere tool in the pay
of the others, and had no chance to gain valuable information.

A hasty search of Shop 13 did not reveal anything missing, and it was
surmised (for Schwen would not talk) that he had not found time to go
about and get all that he was after.

Soon after Schwen's arrest the "Spy Tree," as Tom called it, was cut
down.

"Eradicate certainly did better than I ever expected he would,"
declared Tom. "Well, if all goes well, there won't be so much need for
secrecy after a day or so. We're going to give her a test, and then--"

"Give who a test?" asked Ned, with a smile.

"You'll soon see," answered Tom, with an answering grin. "I hereby
invite you and Mr. Damon to come over to Shop Thirteen day after
to-morrow night and then--Well, you'll see what you'll see."

With this Ned had to be content, and he waited anxiously for the
appointed time to come.

"