time are set down in the fifth volume of this series, entitled: "Air Service Boys Flying For Victory."

Frequently they had found themselves in serious trouble, and their escapes were both numerous and thrilling. Through it all they had been highly favored, since neither of them had thus far met with a serious accident. Numbers of their comrades had been registered as "missing," or were known to have been shot down and lost.

It was no unusual thing a few days after a flier had gone out and failed to return at evening, for a Hun pilot to sail over and drop a note telling that he had fallen in combat, and was buried at a certain place with his grave so marked that it could be easily found.

There seemed to be a vein of old-time chivalry among the German airmen even up to the very last, such as had not marked any other branch of their fighting forces, certainly not the navy. And the Americans made it a point to return this courtesy whenever an opportunity arose.

Tom was proud of his ability to execute that difficult feat known as a "nose-dive." More than once it had extricated him from a "pocket" into which he found himself placed by circumstances, with three or more enemy planes circling around and bombarding him from their active guns.

At such times the only hope of the attacked pilot lay in his ability to drop down as if his machine had received a fatal blow and when once far below the danger point again to recover an even keel.

Jack never doubted what the result would be, having the utmost confidence in his comrade. The wind rushed past his ears as they pitched downward; and just when objects on the ground loomed up suggestively there was the expected sudden shift of the lever, a consequent change in the pointing of the plane's nose, and then they found themselves on the new level, with the motor again humming merrily.

Jack was on the alert and quickly discovered the object that just then enlisted their whole attention. As he had suspected when using the glasses from the higher level, it was a Yankee bomber that lay partly hidden among the bushes where it had fallen. He could easily see the Indian head marking the broken wing.

The pilot was sitting near by as though unable to make a run for it, although Jack imagined he must suspect the approach of danger, for he gripped something that glinted in the sunlight in his right hand. It was, of course, an automatic pistol.

Looking hastily around Jack glimpsed the creeping figures of the two Germans who, having seen the fall of the Yankee plane, must have come out from some place of concealment and were bent on finishing the pilot, or at least taking him prisoner. They had almost reached a point where it would have been possible for them to open fire on the wounded American.

Jack looked in vain for any second figure near the fallen plane. If the pilot had had an observer with him, which was most likely, considering the fact that he had been using a bombing machine, the latter must have been dispatched for relief some time before.

"There they are, Tom!" burst from the one who crouched close to the machine gun, and pointing as he spoke. "Swoop down and let me give them a volley!"

The Huns evidently realized what was coming, and feared that their intended victim might after all escape their hands. Even as Jack spoke there came a shot from below, and a bullet went screaming past close to the ears of the Air Service Boys. It was followed by a second and a third in quick succession.

What the marksmen hoped to do was either to kill the pilot or else to strike some vulnerable part of the engine, thus disabling it and wrecking the plane. Those were chances which had to be taken continually; but as a rule the rapidity of flight rendered them almost negligible.

Jack waited no longer. The two men were about to fling themselves behind friendly trees, and but a small chance remained that he might catch them before they were able to shield themselves by these close-by trunks.

Jack, in his most energetic fashion, commenced to spray the vicinity with a shower of leaden missiles. The chatter of the machine gun drowned any cries from the two men below. The Yankee plane swooped past the spot where the injured pilot still sat at bay, ready to sell his life dearly if the worst came.

CHAPTER II

THE RESCUE

The rat-tat-tat of gunfire suddenly ceased. Jack could no longer cover the spot where the two Huns were hiding behind the tree-trunks, and consequently it would be a sheer waste of ammunition to continue firing.

But already Tom had commenced to circle, and soon they would be swooping down upon the scene from another direction. Jack kept on the alert, so as to note quickly any possible movement of the enemy.

Again he poured a hot fire on the place where he knew the Germans were cowering, tearing up the ground with a storm of bullets as though it had been freshly harrowed. But the sturdy trees baffled him once more.

"Nothing doing, Tom!" he called out, vexed. "We've got to drop down and go it on foot if we want to save that pilot!"

"I see a good landing place!" announced the other almost instantly.

"Great luck! get busy then!"

The ground chanced to be unusually smooth, and the plane, after bumping along for a short distance, came to a stand. Meanwhile, both young fliers had succeeded in releasing themselves from their safety belts.

Together they jumped to the ground and started on a run toward the spot where those crouching figures had last been seen. Of course, the Huns must already know of their landing and would be ready to defend themselves, if not to attack; but, nothing daunted by this possibility, the pair pushed ahead through bushes and past trees.

"Better separate, and attack 'em from two different angles, hadn't we, Tom?" panted Jack presently, as a shot was heard and something clipped a twig from a bush within a foot of his hand.

"Take the left, and I'll look after the right!" snapped out Tom.

Both were armed with automatic pistols, for airmen can never tell when their lives may depend upon their ability to defend themselves, and so seldom make a flight without some such weapon in their possession.

"They're on the run!" cried Jack, in a tone of disgust; for he had really hoped to have a further brush with the skulking enemy.

He sent several shots in their direction whenever he caught glimpses of the bounding figures, but without much hope of striking either of them. Still, they had undoubtedly accomplished the business in hand, which was to save the Yankee pilot.

"He's over this way, Jack," observed Tom, moving to the right still further, after being joined by his comrade. "I can see the opening where he must have struck. The Hun flier didn't bother to follow him down and find out if he'd made a count. He may have been here for some time."

"I see him now," continued Jack eagerly. "And it strikes me there's something familiar about his looks. Yes, we've met that pilot before, Tom. It's Lieutenant Colin Beverly, one of the cleverest Yankee aces of the newer squad."

The aviator had already discovered the Air Service Boys' presence. Doubtless all that had occurred had been noted by him as he sat, waiting for anything that might happen; and the swoop of the American plane, as well as Jack's firing, had of course told him help was near.

"He's waving his hand to us," continued Jack, answering in kind.

"Keep your gun ready for business,"