p
with some object in his hand at which the two boys stared with rising
curiosity. "I've got something here for you!"

"For me?" cried the youth addressed. "I'm ever so much obliged, but it
strikes me I've got beyond the point of playing with a toy balloon;
though honestly now, when I was a kid I used to be pretty fond of
sailing one of 'em at the end of a long string, until it would get away,
and leave me staring up while it climbed toward the clouds."

"Oh, this one is about past doing any climbing, I should say," replied
the pilot, laughing at Jack's description of his childish woes. "In
fact, it's been out during the night, and the heavy air forced it to
come down. Listen, and I'll tell you a strange story that will make you
believe in fairy tales."

"Go on then, please," urged Jack. "You've got me all worked up already.
So there's a history attached to this little balloon, is there?"

"There was _something_ attached to it, something that may mean much
or little to you fellows," came the reply. "This thing was found by a
French dispatch bearer on his way across country. Out of curiosity he
stepped aside to look at the bobbing red object he had noticed among
some bushes in an open field. When he found that it had a paper fastened
to it, which on the outside had an address, he concluded to bring the
whole business along with him. He came here half an hour back inquiring
for Jack Parmly, and on finding you were away at the time left the
balloon and the paper in my charge. Take it, and see what the message
is, Jack!"

CHAPTER V

THE STRANGE WARNING

"Open it, Jack, and see what the message is," urged Tom, as his chum
stood with the scrap of damp paper held between his fingers, having
allowed the sagging little toy balloon to fall at his feet.

Jack was thinking just at that moment of the other message his companion
and he had found attached to the homing pigeon. But of course they could
not possibly have any sort of connection!

He opened the small bit of paper. It had some writing in lead pencil.
Once it had doubtless been plain enough, but the dampness must have
caused it to become faint. Still, Jack could make it out without much
difficulty. This was what he read aloud, so that Tom and the other pilot
could hear:

"_Look carefully to your planes; examine every part. There is
treachery in the air!_"

"That's all, fellows," said Jack, much puzzled, as he turned the paper
over and over, lo