re conducted and lesser agents sent
forth.

Jack had got no further in his deduction when he saw the tall man
returning. He carried a bundle that was wrapped in a cloth, and depended
from his hand by means of a heavy cord, or some sort of handle.

This he set down on the landing, while he passed further words with the
captain; and now it was Potzfeldt who asked the questions, as though he
wished to learn how things were going at the front.

Between queries and guttural replies the hidden air service boys heard a
series of sounds that gave them sudden light. Jack's hand pressed on
Tom's arm, as though in this manner he wished to call the attention of
the other to the noise.

Many times both of them had listened to similar sounds while watching
some pigeon on the barn roof dare a rival to combat, or when wooing his
mate. And as they could easily trace this to the covered package which
Carl Potzfeldt had just brought out of the house, the meaning was
obvious.

Of course there were pigeons in that cage, homing pigeons at that, like
the one Tom had shot! Doubtless had that one escaped its tragic fate the
message it carried would have been delivered to the owner of this lonely
house, in turn to be handed over to one of the messengers from German
headquarters.

And now the German captain, stooping over, took possession of the cage
containing at least two of the trained birds. They would be carried to
some point from which, on another night, a daring Boche airman would
attempt to take them far back of the French front, to hand over to the
agent who was in communication with the master spy, Carl Potzfeldt.

It was all very simple. Nevertheless it was also amazing to realize how
by what might be called a freak of fate the air service boys had been
enabled to discover these facts. But for the accident to the motor they
would not have dreamed of making a landing short of the aviation field
at Bar-le-Duc. Then, had they not caught that woeful sound of loud
sobbing, the idea of looking around would never have occurred to them.

The officer was now starting back to his car, which would carry him
post-haste to German headquarters, where the fresh message in a cipher
code from beyond the French lines might be translated, and the valuable
information it possibly contained be taken advantage of.

Presently the military chauffeur started to swing around a curve that
would allow them to leave the grounds by the same gates through