to them as their headquarters while the search
for the big gun was in progress. Sad at having to leave without having
some word of Mr. Raymond, and without knowing the fate of Bessie and her
mother, Tom and Jack, nevertheless, bore up well and left with their
comrades, going out of Paris on a train that would eventually bring them
to their headquarters.

In a way their mission was a secret one. Yet it was a question if the
Germans did not guess that something like what really was afoot would be
undertaken in order to silence the super-cannon. They were up to all the
tricks of war, and they must have realized that the French would do as
the Germans themselves would do under similar circumstances.

"Well, this sure is some place!" exclaimed Tom, as they reached the camp
where they were to stay until the gun had been destroyed, or until some
other change in plans was necessary. "It's the best aerodrome we've
struck since we began flying in this war."

"I believe you!" echoed Jack.

The place, though newly established just back of the French lines, where
they opposed the German trenches, was well fitted up for the purpose to
which it was to be devoted.

There were a number of canvas hangars for the aeroplanes, there were
living quarters for the men, a wireless station and a well defended camp
where the aviators might live in comfort during the periods between
their flights.

Of course the place was open to attack by German fliers, but this was
true of every place along the line. Sufficient camouflaging had been
done, however, to render the spot reasonably secure from bombing. Of
course a direct attack from in front would be met by the admirable
French system of defense, and there were plenty of reserves that could
be brought up if a general advance were attempted by the Germans. But as
there was no particular place of any military or strategic importance on
that sector, the worst that was to be feared was an attack from the air.

And this would be guarded against both by the French fliers themselves
and by a battery of the newest type of anti-aircraft gun.

"They don't seem to have forgotten much," observed Tom, as he and Jack,
with the others, went to the quarters assigned to them.

"You said something!" exclaimed Jack, admiringly.

Thus had been set up in this locality, where heretofore no aircraft
activities had been carried on to any extent, a most perfect
escadrille.

It was designed to destroy the big Ge