y from a camp located a few miles within the Boche
lines.

There was a harried consultation of the officers, and then orders were
given for a half score of the Allied machines to get ready. Two veteran
French aces were to be in command, with Tom and Jack as helpers, and
some of the American aviators were to go into the battle of the air for
the first time.

"The Huns are evidently going to try to bomb some of our ammunition
dumps behind our lines,"' said one officer, speaking to Tom. "It's up to
you boys to drive 'em back."

"We'll try, sir," was the answer. "We owe the Huns something we haven't
been able to pay off as yet."

Tom referred to the loss of Harry Leroy. So far no word had been
received from him, either directly or through the German aviators, as to
whether he was dead or a prisoner. Letters had passed between Bessie and
Nellie and Jack and Tom, and the sister of the missing youth begged for
news.

But there was none to give her.

"Unless we get some to-day," observed Tom as he and his chum hurried
toward the hangars where their machines were being made ready for them.

"Get news to-day? What makes you think we shall?" asked Jack.

"Well, we might bring down a Fritzie or two who'd know something about
poor Harry," was the answer. "You never can tell."

"No, that's so," agreed Jack. "Well, here's hoping we'll have luck."

By this time there was great excitement in the American aviation
headquarters. Word of the oncoming Hun planes had spread, and not a
flier of Pershing's forces but was eager to get into his plane and go
aloft to give battle. But only the best were selected, and if there were
heart-burnings of disappointment it could not be helped.

Two classes of planes were to be used, the single seaters for the aces,
who fought alone, and the double craft, each one of which carried a
pilot and an observer. In the latter cases the observers were the new
men, who had yet to receive their baptism of fire above the clouds.

Tom and Jack were each detailed to take up one of the new men, and the
air service boys were glad to find that, assigned to each of them,
was the very man he would have picked had he had his choice. They were
eager, intrepid lads, anxious to do their share in the great adventure.

Quickly the machines were made ready, and quickly the fighters climbed
into them. The roar of the motors was heard all over the aerodrome, and
soon the machines began to mount. Up and up they climbe