gasoline to help them follow us."

The air service boys turned their backs on the chateau, but Jack hoped
it would be only a temporary absence for them. He was already beginning
to worry about something else, and of course could not keep his troubles
to himself very long. Consequently when they were about half way back he
again broke out.

"Just happened to think of a thing that's going to bother us some, I'm
afraid, Tom," he suggested.

"What now?" demanded the other.

"If we chuck this stuff into our gas tank, why, out she's bound to pour
through those two holes the bullet made, and that's a fact, Tom."

"Is that all?" asked the other indifferently. "I've got everything handy
to repair those holes in almost two shakes of a lamb's tail. You leave
it to me, Jack."

"You better believe I will, and mighty glad of the chance. Why, do you
know, just the idea scared me stiff. But I do remember now that you
always make it a point to carry along several wooden plugs and some wax
calculated to make an air-tight joint. With that outfit you can soon
have the tank plugged so it won't leak a drop. Bully for you, Tom!"

"I should have looked after that before we left the plane," admitted
Tom. "But the fact was I wanted to take a turn around first; and then
when we struck the road it sort of led us on and on. But it's all right,
Jack."

CHAPTER XXI

AT THE OLD CHATEAU

THE air service boys had no difficulty in retracing their steps,
especially since Tom, with his usual caution, had been careful to
remember the spot where the main road was joined by that coming from the
country cemetery.

Once again they made their way past the ghostly looking stones.

"I can see our boomer now, Tom!" Jack cried, as if he had been a little
afraid that something had happened while they were absent, and that they
would find the airplane missing.

"You want to be mighty careful of that stuff," his chum warned him, as
Jack stumbled over some unnoticed object, and only retained his balance
by a supreme effort.

"That's a fact," mumbled the other. "Especially as there's no more where
this lot came from. I attended to that, all right. But here we are, and
now to get the holes plugged up."

"At last my time to make use of that little outfit has arrived!" Tom
exclaimed. "I've carried it for months, thinking I'd need it badly some
day or other. Well, that time is on us, and this repays me for all my
trouble. Set that pail down, and b