It was impossible for them to talk to one another now, as Jack had the motor going almost full speed, and the noise it made was deafening, or it would have been except for the warm, fur hoods that covered the ears of the fliers. They were warmly dressed for they did not know how high they might ascend, and it is always cold up above, no matter how hot it is on the earth.

Up and up they climbed, and then they flew on and over the enemy lines, keeping close lookout for anything unusual below that would indicate the presence of the battery. Behind them, and off to one side, a fierce aerial battle was going on.

Tom and Jack were eager to get into this and do their share. But they had orders to make their observations, and they dared not 'refuse. They could tell by looking back every now and then that the affair was going well for the Allies, including some of the American airmen, even if the Huns outnumbered them.

Back and forth over the German lines swept the gla.s.s-bottomed Spad, and at a certain point Tom, who was looking down, uttered an exclamation. Of course Jack could not hear, but he could feel the punch in the back his chum administered a moment later.

Jack turned his head, and saw his chum eagerly pointing downward. A moment later he motioned over his left shoulder, pointing backward, as though they had just pa.s.sed over something which would warrant a second inspection.

Jack swung the machine about in a big circle, banking sharply, and then, as he pa.s.sed over the ground covered a little while before, he, too, looked down, and with sharper glance than he had used at first.

What he saw was the ruins of a small French chateau. It had been under heavy fire from the Allied guns, for it had sheltered a German machine gun nest, and some accurate shooting on the part of the American gunners had demolished it a day or so before.

But what attracted the attention of Tom and Jack was that whereas the chateau before the bombardment had stood on a little hill without a tree near it, now there was a miniature forest surrounding it. It was as though trees and bushes had sprung up in the night. As soon as he had seen this, Jack turned to Tom, nodded comprehendingly, and at once started back over the American lines. They had no easy time reaching them, for by this time the fleet of Hun planes had been defeated by the Allies, and had turned tail to run for safety--that is what were left of them, several having been shot down, and at no small cost to the French, English and American forces.

But the defeat of their airmen seemed to anger the Germans, and they opened up with their antiaircraft batteries on the machine in which Tom and Jack were flying homeward. "Woolly bears" and "flaming onions," as well as shrapnel, was used against them, and they were in considerable danger. Jack had to "zoom" several times to get out of reach of the sh.e.l.ls.

They finally reached their aerodrome, however, and as soon as they had landed and their plane was taken in charge by the mechanics the two lads hurried to the commanding officer.

"Well?" he asked sharply, as they saluted. "Did you discover anything?"

"I think so, sir," returned Tom, for Jack had told his chum to do the talking, since the discovery was his. "You remember, sir, the old chateau we put out of business the other day?"

"Yes, I recall it. What about it?"

"This: It seems suddenly to have grown a wooded park around it, and the trees and bushes don't seem to be as fresh as natural ones ought to look."

"You mean they camouflaged the ruins, and have put another battery in the old, chateau?"

"I think so, sir. It wouldn't do any harm to drop a few sh.e.l.ls there.

If it's still a ruin the worst will be that we've wasted a little ammunition and may start the German guns up. And if it is what we think it is, we may blow up the battery."

The commander thought for a moment.

"I'll try it!" he suddenly said. "It's worth all it will cost."

He called an orderly and issued his instructions. Tom and Jack had not yet been dismissed, and now the commanding officer turned to them and said:

"Since you boys were sharp enough to discover this, I'll let you have a front seat at the show which will start soon. Go up and do contact work.

Let the gunners know when they make a hit."

The air service boys could not have wished for anything better.

"Once more for our bus!" exclaimed Jack delightedly, when they were outside.

Their Spad had been refilled with gasoline, or "petrol," as it is called on the other side, and oil had been put in, while the machine guns had been looked to.

"You seem to have spotted it all right, Tom," went on Jack, just as they were about to start, for word came that the American batteries were ready.

"Yes, I was looking down through the gla.s.s, 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 sh.e.l.led the place to drive out the German gunners, the American artillery forces knew just about where to plant the sh.e.l.ls.

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

A moment later the second sh.e.l.l--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 quant.i.ty 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 sh.e.l.l 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 sh.e.l.ls 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 consciousness--that is, he was getting awake. It was the morning after the successful discovery of the hidden German battery, and since this exploit the two lads had not been required to go on duty.

"What's the matter?" asked Jack, opening his eyes and looking at his chum. "Has the mail come in? Any letters?"

"No. I was just thinking," remarked Tom, and though his eyes were fixed on Jack it was clear that his thoughts were somewhere else.

"Thinking, Tom? That's bad business. Have you seen the doctor?"

"Oh, shut off your gas!" ordered Tom. "You're side slipping. First you know you'll come down in a tail spin and I'll have to be looking for a new partner."

"It's as serious as all that, is it?" asked Jack, as he began to dress.

"Well, in that case I withdraw my observation. Go ahead. How's the visibility?"

"Low. We won't have to go up to-day, unless it clears."

"Um. And I was counting on getting a few Huns right after breakfast.

Well, what's your think about, if you really were indulging in that expensive pastime?"

"I was," said Tom, and he got up and also proceeded to put on his clothes. "I was thinking about Harry."

"Oh!" and Jack's voice was decidedly different. It had lost all its flippant tone. "Say, he certainly is in tough luck. I wish we could do something for him--and his sister. Doubtless you were thinking of her, too," and a little smile curled his lips.