"They know too much to bother with an aeroplane by now!" declared Frank,
laughing again. "Why I'm thinking those birds have hardly grown new
feathers in place of the lot they lost that time they fought us so
savagely."

The memory appeared to amuse his cousin also, for he could be heard
laughing heartily, even above the purr of the now steadily going motor
that sent the propellers whizzing around so rapidly; for there was one
fore and aft, as is the case with all biplanes, the engine being behind
the pilot and his companion.

"Tell me if you can remember, was that other aeroplane headed straight
up the lake the last you saw it in the early morning light?" Frank
asked.

"That's right, Frank; but then I couldn't say just how long they kept
along that same course. When those hundreds of old crows came sailing
along on the wind, cawing to beat the band, and going every-which-way, I
lost sight of the biplane. After that it would have to be just guess
work."

"But we've got a good pointer to start with," insisted Frank. "They
wouldn't be so apt to head toward the south, east or west, because in
those directions there are plenty of towns and villages, and these could
report seeing a strange biplane passing over, so giving the police a
clue. No, chances are ten to one they kept right on toward the north.
And there's where we've got to do all our searching today. We can just
comb the whole district over, and anything that looks like the stolen
aeroplane is sure to catch our attention from this height, don't you
think so, Andy?"