were about to start, for word came that the American batteries were
ready.

"Yes, I was looking down through the glass, and when I saw the old
chateau it struck me that it had suddenly grown a beard. I remembered
it before, as being on a bare hill. I thought it was funny, and that I
might be mistaken. But when you agreed with me I knew I was right."

"Oh, the Huns have brought up trees and bushes to disguise the place all
right," declared, Jack. "The only question is whether or not the battery
is hidden there."

But there was not long a question about that. Their machine was equipped
with wireless to signal back the result of the shots, and Jack and
Tom were soon in position. From the maps used when they had previously
shelled the place to drive out the German gunners, the American
artillery forces knew just about where to plant the shells.

There was a burst of fire from the designated battery. Up aloft Jack and
Tom watched the shell fall. It was a trifle over, and a correction was
signaled back.

A moment later the second shell--a big one sailed over the German first
lines, and fell directly on the chateau partly hidden in the woods.

There was a burst of smoke, and with it mingled clouds of dust and
flying particles. Faintly to Tom and Jack, above the noise of their
motor, came the sound of a terrific explosion.

There had been a direct hit on the old ruins, as was proved by the fact
that not only was the German battery put out of commission, but a great
quantity of ammunition hidden in the trees and bushes was blown up, and
with it a considerable number of Germans.

And that it was a place well garrisoned was evident to the air service
boys as they saw a few Huns, who were not killed by the shell and
resultant explosion of the ammunition dump, running away from the place
of destruction.

"That was it all right," said Jack, as he and Tom landed back of their
own lines.

"Yes, and it couldn't have been hit better. I hope that was the battery
they wanted put out of business."

And it was, for no more shells came from that vicinity of the Hun
positions for a long time. The aeroplane observations had given the very
information needed, and Tom and Jack were congratulated, not only by
their comrades, but by the commanding officer himself, which counted for
a great deal.

CHAPTER XIII. A DARING SCHEME

Tom sat up on his bunk and looked across at Jack, who was just showing
signs of returning consci