On and on they flew, changing their height occasionally, and, when they were fired at, which was the case not infrequently, they "zoomed" to escape the flying shrapnel.

But on the whole, they fared very well, and in a comparatively short time they found themselves over the country where, on the maps, was marked the location of Harry Leroy's prison camp.

"There it is!" suddenly exclaimed Tom, but of course Jack could not hear him. However, a punch in Jack's back served the same purpose, and he took his eyes from his instruments long enough to look down. Then a confirmatory glance at the map made him agree with Tom. The air service boys were directly over the prison camp.

This, like so many other dreary places set up by the Germans, consisted of a number of shacks, in barrack fashion, with a central parade, or exercise ground. About it all was a barbed wire stockade and, though the character of these wires did not show, there were also some carrying a deadly electric current.

This was to discourage escapes on the part of prisoners, and it succeeded only too well.

But the camp was in plain sight, and in the central s.p.a.ce could be seen a number of ant-like figures which the boys knew were prisoners.

Whether one of them was Leroy or not, they were unable to say.

But they had reached their objective, and now it was time to act. High time, indeed, for below them batteries began sending up sh.e.l.ls which burst uncomfortably close to them. They were of all varieties, from plain shrapnel to "flaming onions" and "woolly bears," the latter a most unpleasant object to meet in mid-air.

For the Germans were taking no chances. They knew the vulnerable points of their prison camp lay above, and they had provided a ring of anti-aircraft guns to take care of any Allied, machines that might fly over the place. Whether any such daring scheme had been tried before or not, Tom and Jack could not say.

Of course it was out of the question that any great damage could be done in the vicinity of the camp without endangering the inmates, so it was not thought, in all likelihood, that any very heavy air raids would have to be repelled. But in any case, the Huns were ready for whatever might happen.

"Better drop the bombs, hadn't we?" cried Jack to Tom, as he slowed down the motor a moment to enable his voice to be heard.

"I guess so--yes. Drop 'em and then shoot over the camp again and let the packages fall. It's getting pretty hot here."

And indeed it was. Guns were shooting at the two daring air service boys from all sides of the camp.

In the camp itself great excitement prevailed, for the prisoners knew, now, that it was some of their friends flying above them.

There was another danger, too. Not many miles away from the prison camp was a German aerodrome, and scenes of activity could now be noticed there. The Huns were getting ready to send up a machine--perhaps more than one--to attack Tom and Jack.

It was, then, high time they acted, and as Jack again started the engine, he guided the machine over a spot where the anti-aircraft guns were most active.

"There's a battery there I may put out of business," he argued.

Flying fast, Jack was soon over the spot, or, rather, not so much over it, as in range of it. For when an aeroplane drops a bomb on a given objective, it does not do so when directly above, but just before it reaches it. The momentum of the plane, going at great speed, carries any object dropped from it forward. It is as when a mail pouch is thrown from a swiftly moving express train or a bundle of newspapers is tossed off. In both instances the man in the train tosses the pouch or his bundle before his car gets to the station platform, and the momentum does the rest.

It was that way with the bomb Jack released by a touch of his foot on the lever in the c.o.c.kpit of the machine. Down it darted, and, wheeling sharply after he had let it go, the lad saw a great puff of smoke hovering directly over the spot where, but a moment before, Hun gums had been belching at him.

"Good! A sure hit!" cried Tom, but he alone heard his own words. Jack's ears were filled with the throb of the motor. He had two more bombs, and these were quickly dropped at different points on German territory outside the camp.

At the time, aside from the evidences they saw, Jack and Tom were not aware of the damage they inflicted, but later they learned it was considerable and effective. However, they guessed that they had created enough of a diversion to try now to deliver the packages containing the letters and other comforts.

Jack swung the machine at a sharp angle over the prison camp, and as he cleared the barbed wire fence Tom, who had been given charge of the packets, let one go. It fell just outside the barrier, caused by some freak of the wind perhaps, and the lad could not keep back a sigh of dismay. One of the three precious packages had fallen short of the mark, and would doubtless be picked up by some German guard.

But Tom had the satisfaction of seeing the two other bundles fall fairly within the prison fence, and there was a rush on the part of the unfortunate men to pick them up.

"I only hope Harry's there," mused Tom. "That's tough luck to wish a man, I know," he reflected, "but I mean I hope he gets the letters and things."

However, he and Jack had done all that lay in their power to make this possible, and it was now time to get back to their own lines if they could. The place was getting too dangerous for them.

Swinging about in a big circle, and noting that groups of prisoners were now gathered about the place where the packets had fallen, Jack sent the machine toward that part of France where they had spent so many strenuous days.

"They're going to make it lively for us!" cried Jack, as he noted two swift German planes mounting into the air. "It's going to be a fight."

But he and Tom were ready for this. Their Lewis and Vickers guns were in position, and they only awaited the approach of the nearest Hun plane to unlimber them. They mounted steadily upward to get beyond the range of the anti-aircraft batteries and were soon in comparative safety, since the Huns, at this particular sector at least, were notoriously bad marksmen.

With the German planes, that would be a different story, and Tom and Jack soon found this out to their cost.

For one of the Boche machines came on speedily, and much more quickly than the boys had believed possible was within range. The German machine guns--for it was a double plane--began spitting fire and bullets at them. They replied, but did not seem to inflict much damage.

Suddenly Tom saw Jack give a jump, as though in an agony of pain, and then the young pilot crumpled up in his seat.

"Badly hit!" exclaimed Tom with a pang at his own heart. "Poor Jack is out of it!"

The machine, out of control for a moment, started to go into a nose dive, but Tom let go the lever of his machine gun, and took charge of the craft, since it was one capable of dual manipulation. Tom now had to become the pilot and gunner, too, and he had yet a long way to go to reach his own lines, while Jack was huddled, before him, either dead or badly wounded.

CHAPTER XVI. JUST IN TIME

It was with mingled feelings of alarm and sorrow that Tom Raymond sent the speedy Spad aeroplane on its homeward way toward the French lines.

He was worried, not chiefly about his own safety, but on account of Jack; and his sorrow was in the thought that perhaps he had taken his last flight with his beloved chum and comrade in arms. He could not see where Jack had been hit, but this was because the other lad lay in such a huddled position in the c.o.c.kpit. Jack had slumped from his seat, the safety straps alone holding him in position, though he would not have fallen out when the machine was upright as it was at present.

"One of those machine gun bullets must have got him," mused Tom, as he started the craft on an upward climb, for it had darted downward when Jack's nerveless hands and feet ceased their control. For part of the steering in an aeroplane is done by the feet of the pilot, leaving his hands free, at times, to fire the machine gun or draw maps.

Tom had a double object in starting to rise. One was to get into a better position to make the homeward flight, and another was to have a better chance not only to ward off the attack of the Hun planes, of which there were now three in the air, but also to return their fire.

It is the machine that is higher up that stands the best chance in an aerial duel, for not only can one maneuver to better advantage, but the machine can be aimed more easily with reference to the fixed gun.

In Tom's case he did not have access to this weapon, which was fixed on the rim of the c.o.c.kpit where Jack could, and where he had been controlling, it. With Jack out of the fight, through one or more German bullets, it was up to Tom to return the fire of the Huns from his swivel mounted Lewis gun. He was going to have difficulty in doing this and also guiding the craft, but he had had harder problems than this to meet since becoming an aviator in the great war, and now he quickly conquered his worrying over Jack, and began to look to himself.

He gave one more fleeting glance at the crumpled-up figure of his chum, seeking for a sign of life, but he saw none. Then he swung about, turning in toward the nearest Hun airman, and not away from him, and opened up with the machine gun, using both hands on that for a moment, while he steered with his knees.

It was not easy work, and Tom hardly expected to make a direct hit, but he must have come uncomfortably close to the Boche, for the latter swerved off, and for an instant his plane seemed beyond control. Whether this was due to a wound received by the aviator, or to a trick on his part was not disclosed to Tom. But the machine darted downward and seemed to be content to veer off for a while.

The third plane Tom soon saw was not going to trouble him, as it had not speed equal to his own, so that he really had left only one antagonist with whom to deal. And this plane, containing two men, with whom he had not yet come to close quarters, was racing toward him at great speed.

"I guess there's only one thing to do," mused Tom, "and that's to run for it. I won't stand any show at all with two of them shooting at me, while I have to manage the machine and the gun too. If I can beat 'em to our lines I'd better do it and run the chance of some of our boys coming out to take care of 'em. I'd better get Jack to a doctor as soon as I can."

And abandoning the gun to give all his attention to the motor, Tom opened it full and sped on his way. The other machine's occupants saw his plan and tried to stop it with a burst of bullets, but the range was a little too far for effective work.

"Now for a race!" thought Tom, and that is what it turned out to be.

Seeing that he was going to try to get away, the Hun plane, which was almost as speedy as the one Tom and Jack had started out in, took after them. The other German craft was left far in the rear, and the one Tom had shot at appeared to be in such difficulties that it was practically out of the fight.

Thus the odds, once so greatly against our heroes, were now greatly reduced, though not yet equal, since Jack was completely out of the game--for how long Tom could only guess, and he seemed to feel cold fingers clutching at his heart when he thought of this.

But Tom soon discovered, by a backward glance over his shoulder now and then, that his machine, barring accidents, would distance the other, and this was what his aim now was. So on and on he sped, watching the German occupied French territory unrolling itself below him, coming nearer and nearer each minute to his own lines and safety.

Behind them, he and Jack--for the latter had done his share before being wounded--had left consternation in the German ranks. The bombs had done considerable damage--as was learned later--and the dropping of packages within the prison camp was fraught with potential danger to an extent at which the Boches could only guess.