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                      AIR SERVICE BOYS OVER THE RHINE

                       OR, FIGHTING ABOVE THE CLOUDS

                           BY CHARLES AMORY BEACH

            AUTHOR OF "AIR SERVICE BOYS FLYING FOR FRANCE,"
            "AIR SERVICE BOYS OVER THE ENEMY'S LINES," ETC.


    ILLUSTRATED BY
    ROBERT GASTON HERBERT

    THE SAALFIELD PUBLISHING CO.
    AKRON, OHIO       NEW YORK

    MADE IN U.S.A.

    COPYRIGHT, 1919, BY
    GEORGE SULLY & COMPANY


[Illustration: BLOWING UP THE GERMAN MUNITION FACTORY.]




CONTENTS


I DOUBLE NEWS

II ANXIOUS DAYS

III ON TO PARIS

IV SUSPICIONS

V THE BOMBARDMENT OF PARIS

VI THE RUE LAFAYETTE RUINS

VII TOM'S FATHER

VIII WHERE IS MR. RAYMOND?

IX VARIOUS THEORIES

X THE "DUD"

XI A MONSTER CANNON

XII FOR PERILOUS SERVICE

XIII THE SPY

XIV WITH COMRADES AGAIN

XV THE PICKED SQUADRON

XVI MISSING

XVII SEEKING THE GUN

XVIII A CLOUD BATTLE

XIX QUEER LIGHTS

XX THE BIG GUN

XXI DEVASTATING FIRE

XXII OVER THE RHINE

XXIII OFF FOR GERMANY

XXIV PRISONERS

XXV THE ESCAPE




AIR SERVICE BOYS OVER THE RHINE




CHAPTER I

DOUBLE NEWS


"Here they come back, Tom!"

"Yes, I see them coming. Can you count them yet? Don't tell me any of
our boys are missing!" and the speaker, one of two young men, wearing
the uniform of the Lafayette Escadrille, who were standing near the
hangars of the aviation field "somewhere in France," gazed earnestly up
toward the blue sky that was dotted with fleecy, white clouds.

There were other dots also, dots which meant much to the trained eyes of
Tom Raymond and Jack Parmly, for the dots increased in size, like
oncoming birds. But they were not birds. Or rather, they were human
birds.

The specks in the sky were Caudrons. A small aerial fleet was returning
from a night raid over the German ammunition dumps and troop centers,
and the anxiety of the watching young men was as to whether or not all
the airmen, among whom were numbered some of Uncle Sam's boys, had
returned in safety. Too many times they did not--that is not all--for
the Hun anti-aircraft guns found their marks with deadly precision at
times.

The Caudrons appeared larger as they neared the landing field, and Tom
and Jack, raising their binoculars, scanned the ranks--for all the world
like a flock of wild geese--to see if they could determine who of their
friends, if any, were missing.

"How do you make it, Tom?" asked Jack, after an anxious pause.

"I'm not sure, but I can count only eight."

"That's what I make it. And ten of 'em went out last night, didn't
they?"

"So I heard. And if only eight come back it means that at least four of
our airmen have either been killed or captured."

"One fate is almost as bad as the other, where you have to be captured
by the Boches," murmured Jack. "They're just what their name
indicates--beasts!"

"You said something!" came heartily from Tom. "And yet, to the credit of
airmen in general, let it be said that the German aviators treat their
fellow, prisoners better than the Hun infantrymen do."

"So I've heard. Well, here's hoping neither of us, nor any more of our
friends, falls over the German lines. But look, Tom!" and Jack pointed
excitedly. "Are my eyes seeing things, or is that another Caudron
looming up there, the last in the line? Take a look and tell me. I don't
want to hope too much, yet maybe we have lost only one, and not two."

Tom changed the focus of his powerful glasses slightly and peered in the
direction indicated by his chum. Then he remarked, with the binoculars
still at his eyes:

"Yes, that's another of our machines! But she's coming in slowly. Must
have been hit a couple of times."

"She's lucky, then, to get back at all. But let's go over and hear what
the news is. I hope they blew up a lot of the Huns last night."

"Same here!"

The aircraft were near enough now for the throbbing of their big motors
to be heard, and Tom and Jack, each an officer now because of gallant
work, hurried across the landing field.

It was early morning, and they had come, after a night's rest, to report
for duty with others of the brave Americans who, during the neutrality
of this country in the great conflict, went to France as individuals,
some to serve as ambulance drivers, others to become aviators.

The Caudron is the name given to one type of heavy French aeroplane
carrying two or more persons and tons of explosive bombs.

An air raid on the German lines by a fleet of these machines had been
planned. It had been timed for an early hour of the night, but a mist
coming up just as the squadron of heavy machines, each with two men and
a ton or more of explosives, was ready to set out, the hour had been
changed. So it was not until after midnight that the start had been
made.

And now the boys were coming back--that is all who were able to return.
One machine was missing. At least, that was the assumption of Tom and
Jack, for they could count but nine where there should have been ten.
And of the nine one was coming back so slowly as to indicate trouble.

One by one the machines, which ordinarily came back before daybreak,
landed, and the pilot and the observer of each climbed clumsily down
from their cramped seats. They were stiff with cold, in spite of the
fur-lined garments they wore--garments that turned them, for the moment,
into animated Teddy bears, or the likeness of Eskimos.

Their faces were worn and haggard, for the strain of an airship bombing
raid is terrific. But they were quiet and self-possessed as they walked
stiffly across the field to make a report.

"Any luck?" asked Tom, of one he knew; a Frenchman noted for his skill
and daring.

"The best, _mon ami_," he replied with a smile--a weary smile. "We gave
Fritz a dose of bitter medicine last night."

"And he gave us a little in return," sadly added his companion. "Quarre
and Blas--" he shrugged his shoulders, and Tom and Jack knew what it
meant.

They were the men in the missing machine, the Caudron that had not come
back.

"Did you see what happened?" asked Jack.

Picard, to whom Tom had first spoken, answered briefly.

"They caught them full in the glare of a searchlight and let them have
it. We saw them fall. There didn't seem to be any hope."

"But the battery that did the firing--it is no more," added De Porry,
the companion of Picard. "The bombs that Quarre and Blas carried went
down like lead, right on top of the Hun guns. They are no more, those
guns and those who served."

"It was a retributive vengeance," murmured Picard.

Then they passed on, and others, landing, also went to make their
reports.

Some of them had reached their objectives, and had dropped the bombs on
the German positions in spite of the withering fire poured upward at
them. Others had failed. There is always a certain percentage of
failures in a night bombing raid. And some were unable to say with
certainty what damage they had caused.

The last slowly flying machine came to a landing finally, and there was
a rush on the part of the other aviators to see what had happened. When
Tom and Jack saw a limp form being lifted out, and heard murmurs of
admiration for the pilot who had brought his machine back with a
crippled engine, they realized what had happened.

The two brave men had fulfilled their mission; they had released their
bombs over an important German factory, and had the terrible
satisfaction of seeing it go up in flames. But on their return they had
been caught in a cross fire, and the observer, who was making his first
trip of this kind, had been instantly killed.

The engine had been damaged, and the pilot slightly wounded, but he had
stuck to his controls and had brought the machine back.

There was a little cheer for him, and a silent prayer for his brave
companion, and then the night men, having made their reports, and having
divested themselves of their fur garments, went to rest.

"Well, what's on the programme for to-day, Tom?" asked Jack, as they
turned back toward the hangars where they had their headquarters with
others of their companions in the Lafayette Escadrille and with some of
the French birdmen.

"I don't know what they have on for us. We'll have to wait until the
orders come in. I was wondering if we would have time to go and see if
there's any mail for us."

"I think so. Let's go ask the captain."

They had, of course, reported officially when they came on duty, and now
they went again to their commanding officer, to ask if they might go a
short distance to the rear, where an improvised post-office had been set
up for the flying men.

"Certainly, messieurs," replied the French captain, when Tom proffered
the request for himself and his chum. "Go, by all means." He spoke in
French, a good mastery of which had been acquired by our heroes since
their advent into the great war. "Your orders have not yet arrived, but
hold yourselves in readiness. Fritz is doubtless smarting under the dose
we gave him last night, and he may retaliate. There is a rumor that we
may go after some of his sausages, and I may need you for that."

"Does he mean our rations have gone short, and that we'll have to go
collecting bolognas?" innocently asked a young American, who had lately
joined.

"No," laughed Tom. "We call the German observation balloons 'sausages.'
And sometimes, when they send up too many of them, to get observations
and spoil our plans for an offensive, we raid them. It's difficult work,
for we have to take them unawares or they'll haul them down. We
generally go in a double squadron for this work. The heavy Caudrons
screen the movements of the little Nieuports, and these latter, each
with a single man in it, fire phosphorus bullets at the gas bags of the
German sausages.

"These phosphorus bullets get red hot from the friction of the air, and
set the gas envelope aglow. That starts the hydrogen gas to going
and--good-night to Mr. Fritz unless he can drop in his parachute. A raid
on the sausages is full of excitement, but it means a lot of
preparation, for if there has any rain or dew fallen in the night the
gas bags will be so damp that they can't be set on fire, and the raid is
off."

"Say, you know a lot about this business, don't you?" asked the young
fellow who had put the question.

"Nobody knows a _lot_ about it," replied Jack. "Just as soon as he does
he gets killed, or something happens to him. We're just learning--that's
all."

"Well, I wish I knew as much," observed the other enviously.

Tom and Jack walked on toward the post-office, being in rather a hurry
to see if there was any mail for them, and to get back to their stations
in case their services were needed.

As they went along they were greeted by friends, of whom they had many,
for they had made names for themselves, young as they were. And, as a
matter of fact, nearly all the aviators are young. It takes young nerves
for the work.

"Here's one letter, anyhow!" observed Tom, as he tore open a missive
that was handed to him. "It's from dad, too! I hope he's all right. He
must have been when he wrote this, for it's in his own hand."

"I've got one from my mother," said Jack. "They're all well," he went
on, quickly scanning the epistle. "But they haven't received our last
letters."

"That isn't surprising," said Tom. "The mail service is fierce. But I
suppose it can't be helped. We're lucky to get these. And say!" he
exclaimed excitedly, as he read on in his letter. "Here's news all
right--great news!"

Jack looked at his chum. Tom's face was flushed. The news seemed to be
pleasurable.

Jack was about to ask what it was, when he saw a messenger running from
the telephone office. This was the main office, or, at least, one of the
main offices, in that section, and official, as well as general, news
was sometimes sent over the wire.

The man was waving a slip of paper over his head, and he was calling out
something in French.

"What's he saying?" asked Jack.

"Something about good news," answered Tom. "I didn't get it all. Let's
go over and find out. It's good news all right," he went on. "See!
they're cheering."

"More news," murmured Jack. "And you have some, too?"

"I should say so! Things surely are happening this morning! Come on!"
and Tom set off on a run.




CHAPTER II

ANXIOUS DAYS


While Tom and Jack were hastening toward the man who seemed to have
received some message, telephone, telegraph or wireless, from the
headquarters of this particular aviation section, a throng of the
aviators, their mechanicians, and various helpers, had surrounded the
messenger and were eagerly listening to what he had to say.

"I wonder what it can be, Tom," murmured Jack, as the two fairly ran
over the field.

Those of you who have read the two preceding volumes of this series will
remember Tom Raymond and Jack Parmly. As related in the first book, "Air
Service Boys Flying for France; or The Young Heroes of the Lafayette
Escadrille," the youths had, some time previously, gone to a United
States aviation school in Virginia, their native state, and there had
learned the rudiments of managing various craft of the air. Tom's father
was an inventor of note, and had perfected a stabilizer for an
aeroplane that was considered very valuable, so much so that a German
spy stole one of the documents relating to the patent.

It was Tom's effort to get possession of this paper that led him and,
incidentally, his chum Jack into many adventures. From their homes in
Bridgeton, Virginia, they eventually reached France and were admitted
into that world-famed company--the Lafayette Escadrille. Putting
themselves under the tuition of the skilled French pilots, the Air
Service boys forged rapidly to the front in their careers.

It was while on a flight one day that they attacked a man in a motor
car, who seemed to be acting suspiciously along the sector to which our
heroes were assigned, and they pursued him, believing him to be a German
spy.

Their surmise proved correct, for the man, who was hurt when his machine
got beyond control, was none other than Adolph Tuessig, the German who
had vainly tried to buy Mr. Raymond's stabilizer from him, and who had,
later, stolen the paper.

In our second volume, entitled, "Air Service Boys Over the Enemy's
Lines; or The German Spy's Secret," Tom and Jack found further
adventures. On their way to England, whence they had gone to France,
they had met on the steamer a girl named Bessie Gleason. She was in the
company of Carl Potzfeldt. The girl seemed much afraid of him, though he
was her guardian, said to have been so named by Mrs. Gleason, a distant
relative of his. Mrs. Gleason had been on the ill-fated _Lusitania_, and
it was related by Potzfeldt, for purposes of his own, that Bessie's
mother had been drowned. Moreover, he declared that before she died she
had given him charge of Bessie.

Tom and Jack, the latter especially, grew very fond of Bessie, but there
seemed to be a mystery about her and something strange in her fear of
her guardian.

When the two young men reached England, they lost sight, for a time, of
their fellow passengers, but they were destined to meet them again under
strange circumstances.

During one of their flights they landed near a lonely house behind the
German lines. They were traveling in a Caudron, which contained them
both, and on investigating the building after dark they found, to their
surprise, that Bessie and her mother were kept there, prisoners of Carl
Potzfeldt, who was a German spy.

Bessie and her mother were rescued and then departed for Paris, the
latter to engage in Red Cross work, and the boys, remaining with their
fellow aviators, longed for the time when they might see their friends
once more.

But they had enlisted to help make the world safe for democracy, and
they intended to stay until the task was finished. Over a year had
elapsed since the sensational rescue of Bessie and her mother. The
United States had entered the war and the Air Service boys were thinking
that soon they might be able to join an American aviation service in
France.

"What is it? What has happened?" Tom demanded of one of the aviators on
the outskirts of the throng about the messenger. "Have we won a victory
over the Germans?"

"No, but we're going to," was the answer. "Oh, boy! It's great! We're in
it now sure! Hurray!"

"In it? What do you mean?" asked Jack.

"I mean that Uncle Sam has at last stepped over the line! He's sure
enough on the side of the Allies now, and no mistake."

"You mean--" cried Tom.

"I mean," answered Ralph Nelson, another American aviator, "that the
United States has made a big success of the Liberty Bonds loan and is
going to send a million soldiers over here as soon as possible! Say,
isn't that great?"

"Great? I should say so!" fairly yelled Tom. "Shake!" he cried, and he
and his chum and everybody else shook hands with every one whose palm
they could reach. And there were resounding claps on the back, and wild
dances around the green grass, even the French joining in. No not that
word "even," for the French, with their exuberance of spirit, really
started the joy-making.

To the brave men, who, with the British, had so long endured the brunt
of the terrible blows of the Huns alone, the efforts of the United
States of America meant much, though it was realized that it would be
some time before Uncle Sam could make his blows really tell, even though
an Expeditionary Force was already in the field.

"Say, this is the best news ever!" said Jack to Tom, when quiet, in a
measure, had been restored. "It's immense!"

"You said something, old man! It's almost as good news as if you had
come in and told me that you had downed a whole squadron of German
aircraft."

"I wish I could, Tom. But we'll do our share. Shouldn't wonder, before
the day is out, but what we'd get orders to go up and see what we can
spot. But I'm almost forgetting. You had some news of your own."

"Yes, I have. And now I have a chance to finish reading dad's letter."

"But first you can tell me what the special news is, can't you?" asked
Jack. "That is, unless you think it will be too much for me to stand
all in one day--your news and that about Uncle Sam's success in raising
funds and troops."

"Oh, I guess you can stand it," said Tom with a smile. "It's this. Dad
is coming over!"

"He is? To fight?"

"Well, no, not actively. He's a little too old for that, I'm afraid,
though he's anxious enough. But he left for Paris the day he wrote this.
He ought to be here now, for he would, most likely, get off ahead of the
mail, which, sometimes, seems slower than molasses."

"That's right!" exclaimed Jack, with such energy that Tom asked:

"What's the matter? Haven't you heard from Bessie lately?"

"Oh--that!" murmured Jack, but Tom noticed that his friend blushed under
his coat of tan. "Go on," Jack said, a moment later, "tell me about your
father. Is the French government going to give him a big order for his
stabilizer, now that we got that paper away from that sneak of a
Tuessig?"

"Well, I guess dad's trip here has something to do with his aeroplane
device, but he hints in his letter about something else. He said he
didn't want to write too much for fear a spy might get hold of the
information. But you know my father is an expert on ordnance matters and
big guns, as well as in other lines of fighting."

"That's so, Tom. He certainly is a wonder when it comes to inventing
things. But what do you suppose his new mission is?"

"I can't quite guess. But it is for the service of the Allies."

"And you say he's on his way to Paris now?"

"He ought to be there by this time," Tom answered. "I'm going to see if
I can't get permission to send a message through, and have an answer
from dad. Maybe he might get out here to see us."

"Or we could go in and meet him."

"Not for a week. You know we just came back from leave, and we won't be
over our tour of duty for seven days more. But I can't wait that long
without some word. I'm going to see what I can find out."

Tom and Jack, like all the other American fliers, were in high favor
with the French officers. In fact every aviator of the Allied nations,
no matter how humble his rank, is treated by his superiors almost as an
equal. There is not that line of demarcation noticed in other branches
of the service. To be an aviator places one, especially in England and
France, in a special class. All regard him as a hero who is taking
terrible risks for the safety of the other fighters.

So Tom readily received permission to send a message to the hotel in
Paris mentioned by his father as the place where Mr. Raymond would stay.
And then Tom had nothing to do but wait for an answer.

Nothing to do? No, there was plenty. Both Tom and Jack had to hold
themselves in readiness for instant service. They might be sent out on a
bombing expedition at night in the big heavy machines, slow of flight
but comparatively safe from attack by other aircraft.

They might have the coveted honor of being selected to go out in the
swift, single Nieuports to engage in combat with some Hun flier. To
become an "ace"--that is a birdman who, flying alone, has disposed of
five enemies--is the highest desire of an aviator.

Tom and Jack, eager and ambitious, were hoping for this.

Again, in the course of the day's work, they might be selected to go up
in the big bi-motored Caudrons for reconnoissance work. This is
dangerous and hard. The machines carry a wireless apparatus, over which
word is sent back to headquarters concerning what may be observed of the
enemy's defenses, or a possible offensive.

Often the machines go beyond the range of their necessarily limited
wireless, and have to send back messages by carrier pigeons which are
carried on the craft.

By far the most dangerous work, however, is that of "_relage_" or fire
control. This means that two men go up in a big machine that carries a
large equipment. Their craft is heavy and unwieldy, and has such a
spread of wing surface that it is not easily turned, and if attacked by
a German Fokker has little chance of escape. A machine gun is carried
for defense.

It is a function of those in the machine to send word back to the
battery officers of the effect of the shots they are firing, that the
elevation and range may be corrected. And those who go out on "_relage_"
work are in danger not only from the fire of the enemy's batteries, but
often, also, from their own.

Tom and Jack had their share of danger and glory during the week they
were on duty following the receipt of the two pieces of news. They went
up together and alone, and once, coming back from a successful trip over
the enemy's lines, Tom's machine was struck by several missiles. His
cheek was cut by one, and his metal stability control was severed so
that his craft started to plunge.

Tom thought it was his end, but he grasped the broken parts of the
control rod in one hand, and steered with the other, bringing his
machine down behind his own lines, amid the cheers of his comrades.

"And I'm glad to be back, not only for my sake, but for the sake of the
machine. She's a beauty, and I'd have hated like anything to set fire to
her," remarked Tom, after his wound had been dressed.

He referred to the universal practice of all aviators of setting fire to
their craft if they are brought down within the enemy lines, and are not
so badly injured as to prevent them from opening the gasoline tank and
setting a match to it. This is done to prevent the machine, and often
the valuable papers or photographs carried, from falling into the hands
of the enemy.

The end of the week came, the last of seven anxious days, and it was
time for Tom and Jack to be relieved for a rest period. And the days had
been anxious because Tom had not heard from his father.

"I hope the vessel he was coming on wasn't torpedoed," said Tom to his
chum. "He's had more than time to get here and send me some word. None
has come. Jack, I'm worried!" And Tom certainly looked it.




CHAPTER III

ON TO PARIS


Those were the days--and they had been preceded by many such--when
travel across the Atlantic was attended with great risk and uncertainty.
No one knew when a lurking German submarine might loose a torpedo at a
ship carrying men, women and children. Many brave and innocent people
had found watery graves, and perhaps suffered first a ruthless fire from
the German machine guns, which were even turned on lifeboats! So it was
no wonder that Tom Raymond was worried about his father.

"It's queer we can't get any word from the authorities in Paris,"
remarked Jack, as he and his chum were speculating one day on what might
have happened.

"Yes, and that helps to bother me," Tom admitted. "It isn't as if they
weren't trying, for the officers here have done all they can. They've
gotten off my messages, but they say there is no reply to them."

"Then it must mean that your father, if he is in Paris, hasn't received
them."

"Either that, Jack; or else he doesn't dare reply."

"Why wouldn't he dare to, Tom?"

"Well, I don't know that I can give a good reason. It might be that he
is on such a secret mission that he doesn't want even to hint about it.
And yet I can't understand why he doesn't send me at least a message
that he has arrived safely."

As Tom said this he looked at his chum. The same thought was in the mind
of each one:

Had Mr. Raymond arrived safely?

That was what stirred Tom's heart. He knew the danger he and Jack had
run, coming across to do their part in flying for France, and he well
realized that the Germans might have been more successful in attacking
the vessel on which his father had sailed, than they had the one which
had carried Tom and Jack.

"Well, what are we going to do?" asked Jack of his chum. "You know we
arranged, when we should get our leave, to go back to that pretty little
French village, which seemed so peaceful after all the noise of battle
and the roar of the aeroplane engines."

"Yes, I know we planned that," said Tom, reflectively. "But, somehow, I
feel that I ought to stay here."

"And not take our relief?"

"Oh, no. We'll take that," decided Tom. "We must, in justice to
ourselves, and those we work with. You know they tell us an airman must
always be at his best, with muscles and nerves all working together. And
a certain amount of rest and change are necessary, after a week or so of
steady flying. So we'll take our rest in order to be in all the better
shape to trim the Fritzies. But I was thinking of staying right here."

"And not go back into the country?" asked Jack.

Tom shook his head.

"I'd like to stay right here until I get word from my father," he said.
"He may send a message at any time, and he knows I am stationed here. Of
course I could send him word that we're having a little vacation, and
give him our new address.

"But the mails are so mixed up, and the telegraph and telephone systems
are so rushed, that he might not get it. So I think the best thing will
be to stay right here where I'll be on hand to get it the moment word
comes. But don't let me keep you, Jack. You can go, if you want to."

"Say, what do you think I am?" cried his chum. "Where you stick, I
stick! We'll both wait here for word from your father. I have a sort of
feeling that he is all right."

"Well, to tell you the truth, I suppose he is. But, at the same time,
I'm worried. I can't explain it, but I have a sort of sense that he is
in danger."

"Not if he is in Paris, Tom. The German's haven't gotten within striking
distance of that city yet, in spite of their boasts--the boasts of the
Kaiser and of the Crown Prince."

"No, if dad were in Paris I'd feel that he was comparatively safe. But
first I want to know that he is. And yet, even if he has put up at that
house in the Rue Lafayette, where he said in his letter he'd stay, there
may be some danger."

"Danger in Paris? What do you mean, Tom?"

"Well, Paris has been bombed from the air, you know."

"True, Tom. But, say! we've almost come to disregard such mild things as
that from the Huns, haven't we?"

"Well, we'll just stay right on here," decided Tom. "I don't mean to say
that we'll stay around our hangar all the while, but we'll keep in
touch, throughout the day, with the communication headquarters. Dad may
send a message at any time, and I want to get it as soon as it arrives."

Jack could understand his chum's feelings, and so the Air Service boys,
who, some time previous, had sought and received permission to go back
several kilometers into the country for a rest, announced that they
would stay on at the aerodrome.

Nor did they lack excitement. The place where they were stationed was a
busy one. For every twenty pilots and observers there are detailed about
one hundred men as helpers. There are cooks, photographers, mechanics of
various sorts, telephone, telegraph and wireless operators, orderlies
and servants.

Of these Tom and Jack had their share, for it is the business of an
airman to fly and fight, and he does nothing except in that line. He is
catered to and helped in every possible way when not in the air. He has
some one to wait on him, to look after his machine, and to attend to his
hurts, if he is unlucky enough to get any. Of course each flier goes
over, personally, his own craft, but he has oilers and mechanics to do
all the detail work.

"Well, there they go!" exclaimed Tom to Jack one morning, the second of
their "vacation," as they observed a number of "aces" about to go up
and search above the clouds for some Hun to attack.

"Yes, and I wish I was with them!" said Jack.

"Waiting isn't much fun," agreed his chum. "I'm sure I can't understand
why dad doesn't send some word. If this keeps up much longer--Say, Jack,
look at Parla!" he suddenly cried. "What's the matter with him?"

Jack looked. The men, in their machines, had started off to get momentum
for a rise into the air. But there had been a rain and the ground was
soft, which kept down the speed. All the pilots seemed to get off in
fairly good shape except one, Parla by name, who had only recently
secured the coveted designation of "ace."

And then occurred one of those tragedies of flying. Whether he was
nervous at taking a flight in such distinguished company, or whether
something went wrong with Parla's machine never would be known.

He was the last in the line, and as it was rather misty he might have
been anxious not to lose sight of his companions. He did not take a long
enough run, and when he reached the end of the field he was not high
enough to clear the line of hangars that were in front of him.

Some one shouted at him, not stopping to realize that the noise of the
motor drowned everything else in the ears of the pilot.

The luckless man tried to make a sharp turn, to get out of danger. One
of his wing tips caught on the canvas tent, or hangar, and in another
instant there was a crash and a mass of wreckage. From this, a little
later, poor Parla was carried.

But the others did not stay, for though the shadow of death hovered over
the Escadrille, the business of war went on.

After three days Tom and Jack could not stand it any longer. They begged
for permission to go up into the air. It was granted, though officially
they were still on leave. Ascending together in a Caudron, on a
photographing assignment, they were attacked by two swift German
Fokkers.

Tom worked the gun, and to such good effect that he smashed one machine,
sending it down with a crash, and drove the second off. So other laurels
were added to those the boys already had.

"If this keeps on we'll be soon wearing the chevrons of sergeants," said
Jack, as they landed.

"Well, I'd almost give up hope of them to hear from dad," announced
Tom. "I'm going to see if some word hasn't come."

But there was no message. Still the strange silence continued, and Tom
and his chum did not know whether Mr. Raymond had reached Paris or not.
Through his own captain, Tom appealed to the highest authority at the
Escadrille, asking that a last imploring message be sent to the address
in the Rue Lafayette.

This was done, and then followed another day of waiting. At last Tom
said:

"Jack, I can't stand it any longer! This suspense is fierce!"

"But what are you going to do about it?"

"I'm going to Paris! That's what! We'll go there and find my father if
he has arrived. If he hasn't--well, there is still some hope."

"Go to Paris!" murmured Jack.

"Yes. It's the only place where I can make uncertainty a certainty. Come
on, we'll go to Paris!"




CHAPTER IV

SUSPICIONS


Tom Raymond started across the field toward headquarters. Jack followed,
but there was a strange look on the latter's face.

"I don't see how you're going to Paris," remarked Jack, at length. "Do
you mean we're to go in separate machines, or together?"

"Oh, nothing like that!" exclaimed Tom. "We won't go in machines at all.
We'll go by train, if we can get one, or by motor."

"But you're heading for the Escadrille Headquarters office, and--"

"We've got to get official permission to go," explained Tom. "We can't
rush off, whenever we like, as we used to go fishing together."

To his captain Tom explained matters more fully than he had done before.
In effect he related the fact of having received the letter, stating
that Mr. Raymond had started for Paris, presumably to engage in some
work for the French government, or at least for the Allies. Whether he
had arrived or not, and, in the former case, to ascertain why he had
not sent some word to his son, was the object of Tom's quest.

"I've tried and tried, from this end, to get in touch with him,"
explained Tom; "but something seems to happen to my messages. I know
they leave here all right, but after that they are lost. Now I have an
idea that there is so much going on in Paris--so much necessary war
work--that the ordinary lines of communication are choked. But if I
could go to the capital in person I could soon find out whether my
father was at the address he gave."

"And you want, do you, to go together?" asked the kindly French captain,
smiling at Tom and Jack.

"We'd like to go," said Tom.

"And go you shall. I will write the necessary order. You have done well,
and I understand you have some days of leave coming. To them I shall add
more. But come back to me," he added, as he filled out the pass form.
"Come back. We need you Americans now more than ever!"

"We'll come back," promised Tom. "All I want to go to Paris for is to
find out about my father."

"Ah, I envy you," said the captain softly. "Both in the possession of a
father, who must be proud to have such a son as you, and also because
you are going to Paris. It is the most beautiful--the most
wonderful--city in the world. And to think--to think that those
barbarians would sack her! Ah, it is terrible!" and with a sad nodding
of his head, following the shaking of an avenging fist toward the German
lines, he waved Tom and Jack an adieu.

The two Air Service boys lost little time in making their preparations
to leave for the French capital. They had to get certain passes and
papers, and they wished to say good-bye to some of their comrades in
arms. For, more than any other branch of the service, is aviation
uncertain as to life or death. Tom and Jack well knew that some, perhaps
many, of those who wished them "_au revoir_," and "_bonne chance_,"
would not be alive when they returned. And Tom and Jack might not return
themselves. True, their chances were comparatively good, but the
fortunes of war are uncertain.

And so, after certain preliminaries, Tom and Jack, their pet machines in
the hangars, left behind their beloved comrades and were taken by motor
to the nearest railway station. There they secured their tickets and
took their places to wait, with what patience they could, their arrival
in Paris.

The train was well filled with "_permissionnaires_," or soldiers on
leave for a few days of happiness in the capital, and at certain
stations, where more got on, the rush was not unlike that at a crowded
hour in some big city.

"I see something good," remarked Jack, as they sat looking out at the
scenery, glad, even for a brief moment, to be beyond the horrors of war.

"What?" asked his companion.

"There's a dining-car on this train. We sha'n't starve."

"Good enough, I almost forgot about eating," said Tom. "Now that you
speak of it, I find I have an appetite."

They ate and felt better; and it was as they were about to leave the
dining-car to go back to their places, that Jack nudged Tom and
whispered to him:

"Did you hear what he said?"

"Hear what who said?"

"That man just back of you. Did you have a good look at him?"

"I didn't, but I will have," said Tom, and, waiting a moment so as not
to cause any suspicion that his act was directed by his chum, Tom turned
and looked at the person Jack indicated. He beheld a quietly dressed
man, who seemed to be alone and paying attention to no one, eating his
lunch.

"Well, what about him?" asked Tom. "I don't see anything remarkable
about him, except that he's a slow eater. I admit I bolt my food too
much."

"No, it isn't that," said Jack in a low voice. "But don't you think he
looks like a German?"

Tom took another casual glance.

"Well, you might find a resemblance if you tried hard," he answered.
"But I should be more inclined to call him a Dutchman. And when I say
Dutchman I mean a Hollander."

"I understand," remarked Jack. "But I don't agree with you in thinking
that he may be from Holland. Of course men of that nationality have a
right to go and come as they choose, where they can, but I don't believe
this chap is one."

"Why not?"

"Because I heard him mutter something in German."

"Well, lots of Hollanders can speak German, I have no doubt. I can
splutter a few words myself, but not enough to hurt me. I began to pick
up some from the prisoners, after we had that experience with Potzfeldt,
when we realized that even a little knowledge of the Hun's talk, much as
we hate him, would be of service. And so you think you heard this fellow
speak German?" asked Tom, as he pretended to tie his shoe lace, to make
an excuse for pausing.

"I'm sure I did," said Jack.

"What did he say?"

"Something about wishing he had a plate of _metzel suppe_. Of course I
don't guarantee that pronunciation, but--"

"Oh, it'll do," said Tom, graciously. "Well, there's nothing very
suspicious in that, though. I might wish for some _wienerwurst_, but
that wouldn't make me a German spy."

"No. But take one other thing and you'll have to admit that there is
some ground for my belief."

"What's the other thing, old top?" asked Tom, in imitation of some
Englishmen.

"He was making drawings of the railroad line," asserted Jack.

"How do you know?"

"I saw him. He pretended to be looking at the _carte de jour_, and I
caught a glimpse of a sheet of paper on which he was making certain
marks. I'm sure he was sketching out something about the railroad, for
use, maybe, in a future air raid."

"Nonsense!" exclaimed Tom. "As a matter of fact, I don't doubt that the
German secret agents know every foot of ground in and about Paris. They
must have maps of this railroad the same as the French have of some of
Germany's, only you've got to hand it to the Huns! They certainly went
into this thing well prepared the more discredit to us, in a way. But
are you sure of what you say, Jack?" he added, after a moment's thought.

"Positive! I'm sure that man is a German spy, masking as a Hollander or
possibly a Swiss. He's sighing for some of his country's good
cooking--though that's one of the few good things about it--and he's
making some sort of a map."

Tom thought over the matter a moment. The man did not appear to notice
the two chums.

"I'll tell you what we can do," Tom said. "We'll soon be in at the Gare
de l'Est, and we can tip off some of the officers around there. They can
follow this fellow, if they think it's worth while."

"Well, I think it's worth while," said Jack. "If that fellow isn't a spy
I'm a Dutchman!"

As Jack spoke the man looked up and full at the two lads, almost as if
he had heard the words.




CHAPTER V

THE BOMBARDMENT OF PARIS


"There, Jack! what did I tell you? I win! You lose, and it's me for a
fine dinner at your expense! You lose! Do you hear?"

Tom Raymond, with a hearty laugh, clapped his chum on the shoulder, and
seemed mirthfully excited over something. As for Jack Parmly he looked
first at his chuckling comrade and then at the man he suspected of being
a German spy. The latter, who had glanced keenly at the boys, with
something akin to anger on his face, now was plainly puzzled.

"Do you understand?" demanded Tom in a loud voice, which attracted the
attention of many in the car. But a look at the two, showing them to be
Americans and, therefore, to the French mind, capable of any
eccentricity, seemed to make matters right. Most of the diners resumed
their meals.

"See what I mean, Jack?" went on Tom. "You lose! Understand?"

"No, I don't understand," was the low-voiced and somewhat puzzled
answer.

"Then for the sake of your gasolene tank _pretend_ that you do!"
fiercely whispered Tom in his chum's ear. "Play up to my game! Don't you
see that fellow's suspicious of us? He thinks we've been talking about
him. I win, do you understand?"

"Oh, yes," answered Jack, and then, in a louder tone, intended to allay
suspicion on the part of the suspect, he added: "You win all right, Tom!
I'll buy the dinner. I didn't think the train would get in so soon! It's
one on me all right!"

And then, laughing and talking in seeming carelessness, as though they
had not a thought in the world but the friendly wager they had made,
they went back to their coach.

"That was a narrow squeak," observed Tom. "He was getting suspicious all
right, and in another moment might have made an indignant demand of the
guard that we cease observing him. It might have made trouble for us.
We're not members of the secret police, remember."

"Well," remarked Jack, "he might have made trouble for us, but I could
do the same for him. I'd let fall a hint about the map of the railway he
was sketching."

"You mean all right, Jack, but I don't believe your plan would work. If
that fellow really is a German spy, which I doubt, he'd destroy the
map, if he made one, the moment he thought himself in danger."

"Maybe you're right, Tom," agreed his chum, a bit dubiously. "But I
certainly think there is something wrong about that man."

"Maybe you think he is Carl Potzfeldt, disguised, Jack."

"No, nothing like that. Though I wouldn't be surprised if he happened to
be friendly with that sneaking spy. And, speaking of Potzfeldt, Tom,
though he isn't by any means a pleasant subject, do you know we are soon
to be in Paris where--"

"Where Bessie and her mother are, you mean. You're right, old chap, I
haven't forgotten that, and I'll wager one chance for promotion that you
haven't forgotten it either."

Jack's blush was sufficient answer to his friend.

"I couldn't quite understand what you meant, Tom, by talking so suddenly
and loudly about you winning and me losing," went on Jack, as they got
their baggage ready, for the train was about to enter the Paris station.

"That was camouflage, Jack, pure and unadulterated camouflage," answered
Tom with a laugh. "I had to do something in a hurry to get that fellow's
gaze off us, or he might have made a scene, and we don't want that. But
if I had made a wager with you about the time, I'd have won, for here
we are, right on the dot, which is unusual in these days, I believe."

"You said something, Tom. But what are we going to do about our spy?"

"Well, if you insist that's what he is, I think the best thing would be
to notify some secret service official. There must be plenty of them
around the station. Every passenger, before he leaves the station, has
to have his papers stamped by the military authorities. Then's your
chance to tip them off about this chap."

"I'll do it, Tom. I'm not going to lose any chances of putting German
enemies out of the way."

It was about five o'clock when the train pulled into the Gare de l'Est,
and the passengers, including many soldiers on leave, prepared for the
joys of Paris. Tom and Jack, proceeding as did the others to the place
designated for the official stamping of papers, found a chance to tell
their suspicions to an officer, and to point out the man Jack suspected.

"The matter shall be attended to," said the military official, treating
the information with the utmost respect, and evidently considering it of
more importance than Tom imagined would be attached to it. "We are
greatly indebted to you, not only because you are of our beloved
aviators, but because you also think to do this for France--to protect
her from enemies within as well as from those who are without. France
thanks you, gentlemen!" and the aged officer saluted the two young men
as though he considered them his equals.

"Well, now that's off our minds we can get down to the real business
that brought us to Paris," suggested Tom. "And that's to find my
father--if he's here. After that we can look up Bessie and her mother,
if you like, Jack."

"Of course I'll be glad to do that, Tom, and I should think that you--"

"Oh, of a surety, yes, as a Frenchman would say. I'll be happy also, to
see our friends again, but I know Bessie will consider--"

"Oh, drop it, will you?" begged Jack, for he could see that his chum was
about to start to rally him about the girl.

"Then," went on Tom, "the first thing to do, in my opinion, is to get to
this address in the Rue Lafayette where dad said he would make his
headquarters, and see why he hasn't answered any of my messages. When I
once see him, and know he's all right, I'll feel better."

"Even capable of eating that dinner you claim to have won from me?"
asked Jack.

"Of course."

The two Air Service boys had the satisfaction of seeing the "tip" they
gave acted on, for as they left the station they observed the officer
to whom they had reported, detailing a man in plain clothes, evidently
one of the secret police, to follow the man they had watched in the
dining car.

"We can leave the rest to the military," said Tom. "And now let's get to
where we're going."

"Hadn't we better arrange for hotel accommodations, or to stop at a
pension?" asked Jack. "You know Paris is crowded now, even in war times,
and we've got to stay here all night, even if we learn that your father
hasn't yet arrived."

"That's so," agreed Tom. "Maybe we had better get a place to bunk
first."

It would not have been an easy task had they not worn the uniforms of
aviators. But once these were noted, they were welcomed with smiles, and
though at the first place they applied there was no room, the proprietor
busied himself to such advantage that the boys were soon settled in a
big double room with a fine view of a busy section of Paris.

On every side was seen evidence of the joy and satisfaction felt at the
showing made by the progress of the United States in her war programme.

The stars and stripes were seen floating from many staffs, mingled with
the tricolor of France and the English union jack. That Uncle Sam had
at last gotten beyond the bounds of patience with a ruthless and
sneaking enemy and was making energetic warfare against him was welcome
news to those who had so long borne the unequal brunt of battle.

"Americans? Ah, everything that I have is yours!" the hotel proprietor
told Tom and Jack. "You have but to ask. And now come, I will show you
the way to the cellar."

"But we don't care to see the cellar," remarked Tom in wonder. "No doubt
it is a very fine one, monsieur," he added in his best French, which was
nothing to boast of. "No doubt it is most excellent, but we don't care
for cellars."

"Ah, I know, but it is for protection in case of an air raid that I show
it to you. It is there we all take shelter. There have been raids, and
there will be more. It is well to be prepared. It is a well-protected
cellar."

"Oh, well, that's different," observed Jack. "Come on, Tom, we'd better
learn the best and quickest route to the basement. No telling when we
might want to use it."

They descended with the proprietor and saw that he had arranged the
cellar with a false roof of beams, on top of which were sand bags. In
case a bomb was dropped on the hotel or in its vicinity the cellar would
offer almost certain protection.

The boys arranged for a stay of at least a week in Paris, having told
the proprietor their errand to the capital. By the time they had
finished their dinner they found it was too late to set out in search of
Mr. Raymond, as in the changed, war-time Paris little could be done in
the evening. So Tom and Jack retired to their room and their bed.

"Are you going right to the Rue Lafayette?" asked Jack of his chum, the
next day.

"Yes, and if we can't get any news of him there we'll appeal to the
military authorities. I have a letter of introduction to persons high in
authority from our captain."

The boys hailed a taxicab and gave the chauffeur the necessary
directions. They were bowling along through the beautiful streets of
Paris, noting on all sides the warlike scenes, and their thoughts were
busily occupied, when they suddenly became aware that something had
happened.

Like a thunderbolt from a clear sky there sounded a terrific explosion,
and at no great distance. The concussion shook the ground, and they
could feel the taxicab tremble under the shock, while the chauffeur
instantly threw on all brakes, making the machine skid dangerously.

"What is it? What's the matter?" yelled Jack.

"Airship raid most likely!" shouted Tom. "Boches are dropping bombs on
Paris! Oh, where's our cellar, Jack?"

The taxicab driver jumped down and opened the door.

"You had best alight, gentlemen," he said. "You must seek shelter."

"Is it an airship raid?" asked Tom.

"No, there is not an airship in sight. No such alarm has been sounded by
the police. I fear the bombardment of Paris by the Germans has begun!"




CHAPTER VI

THE RUE LAFAYETTE RUINS


Tom Raymond and Jack Parmly alighted from the taxicab more quickly than
they had gotten in. The chauffeur was anxiously scanning the sky.
Excited men, women and children were rushing about, and yet it was not
such excitement as might be caused by the first shelling of the
beautiful city. It was more, as Tom said afterward, as though the
populace had been taken by surprise by a new method in the same kind of
warfare, for an occasional German Zeppelin or a bombing aircraft had,
before this, dropped explosives. To these the French had become as much
accustomed as one ever can to such terrible means of attack.

But this was different. There was no sign of a Hun aircraft, and, as the
chauffeur had said, no police warning had been sounded.

"What is it?" asked Jack.

"It is a bombardment, that is all I know," replied the taxicab driver.
He spoke in French, a language which the two boys used fairly well,
though, as has been said, their accent left much to be desired.

"You had best seek shelter until it is over," went on the man. "I shall
do so myself." He seemed to pause suggestively, and Jack handed him some
money.

"_Merci_," he murmured, and an instant later was careening down the
street at full speed.

"He isn't losing any time," said Jack.

"No. And perhaps we hadn't better, either. Where'd that shell fall?"
asked Tom.

"I don't know, but it must have been somewhere about here, judging by
the noise. Look, the crowd's over that way," and he pointed to the left.

It was true. Careless of the danger of remaining in the open, men, and
women, too, as well as some children, were rushing toward the place
where, undoubtedly, the shell from the German gun had fallen.

"Might as well take it in," suggested Jack. "I don't want to crawl down
into a cellar or a subway quite yet, even if there's one around here; do
you?"

"No," answered Tom, "I don't. Go on, I'm with you."

They followed the throng, but could not resist the impulse to gaze
upward now and then for a possible sight of another shell, which, they
half hoped, they might observe in time to run for shelter. But of course
that would have been out of the question. However, quiet succeeded the
din of the explosion, which had been close to the spot where the taxicab
had stopped and the boys had alighted.

Following the crowd, Tom and Jack came to a side street, and one look
down it showed the havoc wrought by the German engine of death. The
shell, of what kind or calibre could not be even guessed, had fallen on
top of an establishment where a number of women and girls were employed.
And many of these had been killed or wounded. There were heart-rending
scenes, which it is not good to dwell upon. But, even in the terror and
horror, French efficiency was at the fore.

Ambulances were summoned, a guard was thrown about the building, and the
work of aiding the injured and tenderly carrying out the dead was begun.
A vast and excited throng increased in size about the building that had
been hit and there was much excitement for a time.

Tom and Jack managed to get to a place where they could get a view of
the havoc wrought to the structure itself, and the first thing that
impressed them was mentioned by Jack, who said:

"They didn't use a very big shell, or there wouldn't have been such
comparatively slight material damage done."

"The force was mostly expended inside the building," suggested Tom.

"Even so, if it had been a big shell, the kind they fired at Verdun and
Liège, there'd be a crater here big enough to put a church in. As it is,
only the two top stories are wrecked."

"That's right," agreed Tom. "I wonder what sort of explosive they are
using? Must have been one from a bombing aeroplane."

"No, monsieur," interrupted a _gendarme_ who was standing near. "Pardon,
for speaking," he went on, with a salute, "but there was no airship
observed over Paris at all. The shell came out of the clear sky."

"But it couldn't have," insisted Jack, in reply to this policeman. "If
the Germans are firing on Paris they must have some place from which to
shoot their gun. Either on the ground or from an airship."

"It was not an airship," insisted the _gendarme_. "Excuse me for
insisting this to one who is in the air service," and he pointed with
pride to the uniform the boys wore, "but I have seen several air raids,
and I know! There was no airship seen, or I would have blown the alarm,"
and he motioned to his whistle which he carried for that purpose.

"It could have come from an immense airship, so high up as to be beyond
observation," suggested Jack. "That's possible. Probably the Germans
didn't want to be bombarded themselves by aircraft guns here, and they
flew high."

The police officer shook his head. He was not convinced.

"But, man, how else could it be?" asked Tom, in some heat. "The Huns
have to rest their gun somewhere, and you--Say, Jack!" he suddenly
exclaimed, his face paling slightly, "you don't suppose they have broken
through, do you?"

"Through our lines about Paris? Never!" cried the police officer. "They
shall not pass! Our brave soldiers have said it, and they will maintain
it. They shall not pass!"

"And yet," mused Tom, as he looked at the rescue work going on, "what
other explanation is there? It's a bombardment of Paris all right, by
German shells. If they don't come from an aeroplane, high up, they must
come--"

His words were drowned by another great concussion, but farther off. The
ground trembled, but there was no sign of flying debris.

"Another!" cried the _gendarme_. "There goes the gun again!"

"I didn't hear any gun," observed Jack. "What we heard was the explosion
of the shell. Look up, Tom, and see if there's a Hun plane in sight. If
there is, pity we haven't our machines right now."

The boys carried, slung over their shoulders, powerful binoculars, and
with these they swept the sky. Others about them were doing the same. By
this time the most seriously injured had been carried to the hospitals,
and the dead had been removed, while those only slightly hurt, as well
as those in the factory not at all injured, were telling their
experiences. The second explosion seemed to create great terror.

"There isn't a sign of a hostile plane," said Tom, as he swept the sky
with his glasses.

"I can't see any either," observed Jack. "And yet--"

There sounded the unmistakable roar of an aircraft's propeller.

"There she is!" cried some one.

But it was one of the first of a series of French planes that had
hastily ascended to search the heavens for a sight of the supposed
German craft that had dropped the bombs.

"What a chance we're missing!" murmured Jack.

"Yes," agreed Tom. "But they're going to have some flight before they
locate that Hun. There isn't so much as a speck in the sky except the
French craft."

"Let's go and see where that other explosion was," suggested Jack, when
they had observed several of the French planes scurrying to and fro over
the city, climbing higher and higher in search of the enemy.

"I'm with you," announced Tom. "I wonder what dad thinks of this?"

"It'll be something new for him," said Jack. "He'll have a good chance
to see how his stabilizer works, if they're using it on these planes
here. And maybe he can invent a better one."

"Perhaps," returned Tom. "But, Jack, do you know I'm worried about one
thing."

"I have more than that on my mind, Tom. There are mighty serious times
all about us, and it's terrible to think of those poor women and girls
being killed like rats in a trap. I'd just like to be in my plane, and
with a full gun, and then have a go at the Hun who did this."

"So would I," agreed Tom, as they made their way out of the crowd and in
the direction in which many of the populace were hurrying to go to the
scene of the second explosion. "But, Jack, do you know I shouldn't be
surprised to learn that the shell was not from an airship at all."

"Where would it be from then?"

"The Germans may have massed such a lot of troops at some point opposite
the French lines, that they have broken through and have brought up
some of their heavy guns."

Jack shook his head.

"I don't believe they could do it," he said. "You know the nearest
German line is about seventy miles from Paris. If they had started to
break through, and had any success at all, the news would have reached
here before this. And reinforcements would be on the way. No, it can't
be. There must be some other explanation."

"But what is it?" asked Tom. "They've got to get nearer than seventy
miles to bombard Paris. You know that."

"I don't think I really _know_ anything about this war," said Jack
simply. "So many strange, things have happened, so many old theories
have been discarded, and so many new things have been done that we don't
know where we are."

"Well that's true. And yet how could the Germans get near enough to
bombard Paris without some word of it coming in?"

"I don't know. But the fact remains. Now let's get to where the second
shell fell. Maybe we can see a fragment of it and--"

Once again the words were interrupted by an explosion. This time it was
closer and the shock was greater.

"That's the third!" cried Jack.

"Yes," added Tom, looking at his watch, "and it's just half an hour
since the first one fell. That indicates they're firing every fifteen
minutes. Jack, there's something weird about this."

"You're right. That last one came rather close, too. I wonder where it
fell?"

A man, passing them, running in a direction away from the sound of the
last explosion, heard Jack's question. He paused long enough to say;
"That shell fell in Rue Lafayette. Several buildings are in ruins. Many
have been killed! It is terrible!"

"Rue Lafayette!" gasped Jack. "That--"

"That's where my father is supposed to be staying!" exclaimed Tom.
"Come! We must see what happened!"




CHAPTER VII

TOM'S FATHER


With anxious hearts the Air Service boys ran on. There was no need to
ask their way, for they had but to follow the throng toward the scene of
the most recent exhibition of the Hun's frightfulness and horror.

As they drew near the Rue Lafayette, where Mr. Raymond had said he
intended to stay while in Paris, the boys were halted by an officer on
the outskirts of the throng.

"Pardon, but you may not go farther," he said, courteously enough.
"There is danger. We are about to sound the alarm so that all may take
to shelter. The Boches are raiding Paris again."

"We know it," said Tom. "But it is no idle curiosity that takes us on."

"No?" politely questioned the policeman.

"No. I am seeking my father. He wrote to me that he would stop in the
Rue Lafayette, and I have not heard from him since. I was told that the
last shell fell in that street."

"It did," assented the officer, "and it demolished two houses and part
of another. Many were killed and injured."

"Then I must see if my father is among them!" insisted the young
aviator.

"Pardon, monsieur, it is not possible. I have my instructions, and--"

He stopped, and for the first time seemed to become aware of the
uniforms worn by Tom and Jack. Then the officer saluted as though proud
to do it.

"Ah," he murmured. "Of the Lafayette Escadrille! You may go where you
will. Only I hope it is not into danger," he said, as he drew aside for
them to pass. "Pardon, I did not at first sense who you were. France
owes you much, messieurs. Keep your lives save for her!"

"We will," promised Tom, as he hurried on, followed by Jack.

They came to the head of the street they sought, and, looking down it,
beheld ruins greater than they had seen before. As the officer had said,
two buildings had been completely demolished, and a third partly so, the
wreckage of all mingling. And amid these ruins police and soldiers were
working frantically to get out the injured and remove the dead, of whom
there was a sad number.

Tom's face was white, but he kept his nerve. He had been through too
many scenes of horror, had been too near death too often of late, as had
his chum, to falter now, even though his father might be among those
buried in the wreckage caused by the German shell.

"Do you know what number your father was to stop at?" asked Jack.

"Yes, I have his letter," Tom answered. "I'm afraid, Jack, it was in one
of those buildings that have been blown apart."

"No, Tom!"

"I'm afraid so. But, even at that, he may have had a chance for his
life. He may have been out, or, after all, he may not have arrived yet.
I'm not going to give up hope until I have to."

"That's the way to talk, old man. I'm with you to the last."

They pressed on, and populace and officers alike gave way before them as
they saw the uniforms.

"We've got to help!" declared Tom. "We must pitch in, Jack, and lend a
hand here. The soldiers seem to be in charge. Let's report to the
commanding officer and offer our services."

"But your father?"

"That's the best way to find him if he's in those ruins. Let us help get
the unfortunates out. I hope I don't find him, but I must make sure."

Making their way through the press of people, which, under order of the
police and military authorities, had begun to disperse in some small
measure, Tom and Jack reported to the officer in charge, giving him
their names and rank, at the same time showing their papers.

"We want to help," the lads told him.

"And I ask no better," was the quick response. "There are dead and dying
under that pile. They must be gotten out."

And then began heart-rending scenes. Tom and Jack did valiant work in
carrying out the dead and dying, in both of which classes were men,
women and children.

The German beasts were living up to the mark they had set for themselves
in their war of frightfulness.

Each time a dead or injured man was reached, to be carried out for
hospital treatment or to have the last sad rites paid him, Tom nerved
himself to look. But he did not see his father, and some small measure
of thankfulness surged into his heart. But there were still others
buried deep under the ruins, and it would be some time before their
bodies, dead or alive, could be got out.

As the soldiers and police worked, on all sides could be heard
discussions as to what new form or manner of weapon the Germans were
using thus to reach Paris. Many inclined to the theory that it was a new
form of airship, flying so high as to be not only beyond ordinary
observation, but to be unreachable by the type of planes available at
Paris.

"If we could only find a piece of the shell we could come nearer to
guessing what sort of gun fired it," remarked Tom, as the two Air
Service boys rested a moment from their hard, terrible labors.

"Do you mean if it was dropped from an airship it wouldn't have any
rifling grooves on it?" asked Jack.

"That's it. A bomb, dropped from an aeroplane, would, very likely, be
only a sort of round affair, set to explode on contact or by a time
fuse. But if it was a shell fired from a long-range gun, there might be
enough of it left, after the explosion, to observe the rifling."

"There isn't a gun with a range long enough to reach Paris from the
nearest German lines, unless they have broken through," said Jack.

"Well, the last may have happened; though I should think we'd have got
some word of it in that case. There'd be fierce fighting if the Germans
tried that, and we'd rush reinforcements out in taxicabs as the Paris
soldiers went out once before."

"Do you think then," asked Jack, as they went back, after their brief
respite, to their appalling labors, "that they have a gun long enough
to fire from their nearest point, which is about seventy miles from this
city?"

"I don't know what to think," remarked Tom. "It seems like a wild dream
to speak of a gun that can shoot so far; and yet reality is over-topping
many wild dreams these days. I'm going to reserve judgment. My chief
concern now, though of course I'm not going to let it interfere with my
work, is to find my father. If he should have been in here, Jack--"

Tom did not finish, but his chum knew what he meant, and sympathized
with his unexpressed fear for the safety of Mr. Raymond.

Digging and delving into the ruins, they brought out the racked and
maimed bodies, and there was more than one whose eyes were wet with
tears, while in their hearts wild and justifiable rage was felt at the
ruthless Germans.

Ten had been killed and nearly twice that number wounded in the third
shell from the Hun cannon.

From a policeman Tom learned that one of the two buildings that had been
demolished was the number given by Mr. Raymond as the place he would
stay.

"The place he picked out may have been full, and he might have gone
somewhere else," said Tom. "We've got to find out about that, Jack."

"That's right. I should think the best person, or persons, to talk to
would be the janitors, or '_concierges_,' as they call 'em here."

"I'll do that," responded Tom.

Aided by an army officer, to whom the boys had recommended themselves,
not only by reason of their rank, but because of their good work in the
emergency, they found a man who was in charge of all three buildings as
a renting agent. Fortunately he had his books, which he had saved from
the wreck.

"You ask for a Monsieur Raymond," he said, as he scanned the begrimed
pages. "Yes, he was here. It was in the middle building he had a room."

"In the one that was destroyed?" asked Tom, his heart sinking.

"I regret to say it--yes."

"Then I--then it may be all up with poor old dad!" and Tom, with a
masterful effort, restrained his grief, while Jack gripped his chum's
hand hard.




CHAPTER VIII

WHERE IS MR. RAYMOND?


Tom Raymond, having gone through a hard school since he began flying for
France, soon recovered almost complete mastery of himself. The first
shock was severe, but when it was over he was able to think clearly.
Indeed the faculty of thinking clearly in times of great danger is what
makes great aviators. For in no other situation is a clear and quick
brain so urgently needed.

"Well, I'm sure of one thing, Jack," said Tom, as they walked away from
the fateful ruins. "Of those we helped carry out none was my father. He
wasn't among the injured or dead."

"I'm sure of that, too. Still we mustn't count too much on it, Tom. I
don't want you to have false hopes. We must make sure."

"Yes, I'm going to. We'll visit the hospitals and morgues, and talk with
the military and police authorities. In these war times there is a
record of everybody and everything kept, so it ought to be easy to trace
him."

"He arrived all right, that's settled," declared Jack. "The agent's
record proves that."

"Yes. I'd like to have a further talk with that agent before we set out
to make other inquiries."

This Tom was able to bring about some time later that day. The agent
informed the lad that Mr. Raymond, contrary to his expectations, had
arrived only the day before. Where he had been delayed since arriving in
Europe was not made clear.

"But was my father in the building at the time the shell struck here?"
asked Tom. "That's what I want to know."

Of this the man could not be certain. He had seen Mr. Raymond, he said,
an hour or so before the bombardment, and the inventor was, at that
time, in his room. Then he had gone out, but whether he had come back
and was in the house when the shell struck the place, could not be said
with certainty.

But if he had been in his apartment there was little chance that he had
been left alive, for the explosion occurred very near his room,
destroying everything. Tom hoped, later, to find some of his father's
effects.

"There is just a chance, Jack," said the inventor's son, "that he wasn't
in his room."

"A good chance, I should say," agreed the other. "Even if he had
returned to his room, and that's unlikely, he may have run out at the
sound of the first explosion, to see what it was all about."

"I'm counting on that. If he was out he is probably alive now. But if he
was in his room--"

"There would be some trace of him," finished Jack.

"And that's what we've got to find."

The police and soldiers were only too willing to assist Tom in his
search for his father. The ruins, they said, would be carefully gone
over in an endeavor to get a piece of the German shell to ascertain its
nature and the kind of gun that fired it. During that search some trace
might be found of Mr. Raymond.

It did not take long to establish one fact--that the inventor's body was
not among the dead carried out. Nor was he numbered with the injured in
the hospitals. Careful records had been kept, and no one at all
answering to his description had been taken out or cared for.

And yet, of course, there was the nerve-racking possibility that he
might have been so terribly mutilated that his body was beyond all human
semblance. The place where his room had been was a mass of splintered
wood and crumbled masonry. There was none of his effects discernible,
and Tom did not know what to think.

"We've just got to wait," he said to Jack, late that afternoon, when
their search of the hospitals and morgues had ended fruitlessly.

Meanwhile the French airmen had been scouring the sky for a sight of the
German craft that might have released the death-dealing bombs on the
city. But their success had been nil. Not a Hun had been sighted, and
one aviator went up nearly four miles in an endeavor to locate a hostile
craft.

Of course it was possible that a super-machine of the Huns had flown
higher, but this did not seem feasible.

"There is some other explanation of the bombardment of Paris, I'm sure,"
said Tom, as he and Jack went to their lodgings. "It will be a surprise,
too, I'm thinking, and we'll have to make over some of our old ideas and
accept new ones."

"I believe you're right, Tom. But say, do you remember that fellow we
saw in the train--the one I thought was a German spy?"

"To be sure I remember him and his _metzel suppe_. What about him? Do
you see him again?" and Tom looked out into the street from the window
of their lodging.

"No. I don't see him. But he may have had something to do with shelling
the city."

"You don't mean he carried a long-range gun in his pocket, do you,
Jack?" and Tom smiled for the first time since the awful tragedy.

"No, of course not. Still he may have known it was going to happen, and
have come to observe the effect and report to his beastly masters."

"He'd be foolish to come to Paris and run the chance of being hit by his
own shells."

"Unless he knew just where they were going to fall," said Jack.

"You have a reason for everything, I see," remarked Tom. "Well, the next
time we go to headquarters we'll find out what they learned of this
fellow. You know we started the secret service agents on his trail."

"Yes, I know. Well, I was just sort of wondering if he had anything to
do with the bombardment of Paris. You've got to look for German spies
now, even under your bed at night."

The boys felt they could do nothing more that day toward finding Mr.
Raymond. A more detailed and careful search of the ruins might reveal
something. Until this was accomplished nothing could be done.

They ate a late supper, without much in the way of appetites, it must be
confessed, and then went out in the streets of Paris. There seemed to be
few signs of war, aside from the many soldiers, and even the
bombardment of a few hours earlier appeared to have been forgotten. But
of course there was grief in many hearts.

It was early the next morning, when Tom and Jack were getting ready to
go back to the ruins in the Rue Lafayette, that, as they left their
lodgings, they heard in the air above them the familiar sounds of
aeroplanes in flight, and the faint popping of machine guns, to which
was added the burst of shrapnel.

"Look!" cried Jack. "It's a battle in the air. The Huns are making
another raid. Now we'll see how they bomb the city."

But it did not turn out to be that sort of raid. The German craft were
flying low, apparently to get a view of the havoc wrought the day
before. Possibly photographs were being taken.

But the French aeroplanes were ready for the foe, and at once arose to
give battle, while the anti-aircraft guns roared out a stern order to
retreat. It was a battle above the city and, more than once, Tom and
Jack wished they could be in it.

"We'll have to get back to our hangars soon," mused Tom, as they watched
the fight. "We can't be slackers, even if I can't find my father," he
added bravely.

The French planes were too much for the Germans, and soon drove them
back beyond the Hun lines, though perhaps not before the enemy aviators
had made the observations desired.

"Well, they didn't see much," remarked Jack. "As far as any real damage
was done to Paris it doesn't count, from a military standpoint."

"No, you're right," agreed Tom. "Of course they have killed some
noncombatants, but that seems to be the Boche's principal form of
amusement. As for getting any nearer to the capture of Paris this way,
he might as well throw beans at the pyramids. It's probably done for the
moral, or immoral, effect."

And this seemed to be the view taken of it by the Paris and London
papers. The method of bombardment, however, remained a mystery, and a
baffling one. This was a point the military authorities wished to clear
up. To that end it was much to be desired that fragments of the shell
should be found. And to find them, if possible, a careful search was
made, not only in the ruins of the Rue Lafayette, but at the other two
places where the explosions had occurred.

In no place, however, was a large enough fragment found to justify any
conclusive theories, and the Parisians were forced to wait for another
bombardment--rather a grim and tense waiting it was, too.

But the careful search of the Rue Lafayette ruins proved one thing. The
body of Tom's father was not among them, though this did not make it
certain that he was alive. He may have been totally destroyed, and this
thought kept Tom from being able to free his mind of anxiety. He dared
not cable any news home, and all he could do was to keep on hoping.
These were anxious days for him and Jack.

Their leave of absence had been for a week only, but under the
circumstances, and as it was exceptionally quiet on their sector, they
were allowed to remain longer. Tom wanted to make a more thorough search
for his father, and the police and military authorities helped him. But
Mr. Raymond seemed to have completely disappeared. There was no trace of
him since the agent for the Rue Lafayette buildings had seen him leave
his room just prior to the falling of the shell.

Jack inquired about the man he suspected of being a German spy. The
secret service men had him under observation, they reported, but, as
yet, he had not given them any cause to arrest him. They were waiting
and watching.

Meanwhile active preparations were under way, not only to discover the
source of the bombardment of Paris, but to counteract it. Extra
anti-aircraft guns, of powerful calibre, were erected in many places
about the city, and more airmen were summoned to the defense.

As yet there had been no resumption of the bombardment, and there were
hopes that the German machine, whatever it was, had burst or been put
out of commission. But on the second day of the second week of the boys'
stay in Paris, once more there was the alarm and the warning-from the
soldiers and police, and again came that explosion.

The bombardment of Paris was being renewed!




CHAPTER IX

VARIOUS THEORIES


Two things were at once apparent to Tom and Jack as they hurried out of
their _pension_. One was that the people of Paris were not seeking
shelter after the warnings as quickly as they had done at first, and the
other was that there was evident curiosity on all sides to see just what
damage would be done, and from which direction it would come. With an
almost reckless disregard for their safety, if not for their lives, the
Parisians fairly flocked out of doors to see the results of the Huns'
bombardment. It was in vain that the police and military urged them to
seek safety in cellars or the places provided.

This time only one shell fell near enough to Tom and Jack to make the
explosion heard, and that was so faint as to indicate that it was some
distance off. What damage had been done could only be guessed at.

"But we'll find out where it is, and go take a look," said Jack.

"Maybe it'll hit right around here if we stay," suggested his chum.

"Well, I'm not taking that chance," Jack went on. "Let's find out where
it landed this time."

This they could do through their acquaintance with the military
authority of the district where they were then staying. A telephonic
report was at once received, giving the quarter where the shell had
landed. It had fallen in one of the public squares, and though a big
hole had been torn in the ground and pavement, and several persons
killed and wounded, no material damage had been done. As for any
military effect of the shell, it was nil.

The firing was done in the early evening hours, and Tom and Jack learned
that, almost to the second, the shots were fifteen minutes apart.

There was one theory that an underground passage had been made in some
manner to within a comparatively few miles of Paris, and from that point
an immense mortar sent up the shells in a long trajectory.

Another theory was that traitors had let the Germans through the French
lines at a certain place, so they could get near enough to Paris to
bombard it.

And of course the gigantic airship theory had its adherents.

But, for a time at least, no one would admit the possibility of a gun
with range sufficient to shoot into Paris from the nearest German lines.
The range, sixty-odd miles, seemed too great for practical belief,
however nicely it might work out in theory.

"And you must remember that the gun, if gun it is, couldn't be in the
very first German line," said Tom, who had studied ordnance. "It must be
at least ten miles back, to allow for sufficient protection from the
French guns. That would make it shoot about seventy-two miles, and I
don't believe any gun on earth could do it!"

"Neither do I," added Jack. "We've got to dope out something else. But
this isn't finding your father, Tom."

"I know it, and I don't mind admitting I'm clean discouraged about him,
Jack. If he's alive why doesn't he send me some word? He must know where
I am, and, even if he doesn't know I'm in Paris, they would forward any
message he might send to our aeroplane headquarters."

"That's right. But what are you going to do about it?"

"I hardly know. He may still be in Paris, but it's such a big city that
it's hard to find him. Then, too, I'm thinking of something else."

"What's that, Tom?"

"Well, dad may not want us to know where he is."

"Why in the world would he want such a thing as that?"

"Well, he might be followed, or bothered by spies. Perhaps he has come
over to do some special work for the French or English army people.
Maybe a spy was after him just before the big German gun wrecked his Rue
Lafayette house. He may have considered this a good chance to play dead,
and that's why he doesn't send some word to me."

"That's a good theory. But it isn't very comforting."

"No, but there isn't much comfort in war times. We've got to make the
best of it."

"I guess you're right, Tom. Now do you want to go look at the latest
work of the Hun?"

"Might as well. The bombardment seems over for the night."

"I wonder why it is they don't fire after dark."

"Probably afraid of giving the location of their cannon away by the
flashes. They'd be seen at night; but during the day, if they used
smokeless powder, or a smoke screen in case they can't get smokeless
powder for such a big gun, it would be hard to locate the place where
the shots come from. So we're comparatively safe after dark, it seems."

Later this was not to prove to be the case, but it was when Tom spoke.

The boys went to the section of the city in which the last shells had
fallen. While comparatively little damage had been done, a number of
persons had been killed and injured, children among them. Some fragments
of the shells were picked up, but not enough to make certain any
particular theory in regard to the gun.

"But if it's a gun, where could it be placed?" queried Tom of an
officer. "The Germans haven't broken through, have they?"

The French officer shook his head.

"No. And please God they will never get through," he said. "But there is
a gun somewhere, I am sure of that."

"Do you mean to say within ten or fifteen miles of Paris?" Jack wanted
to know.

"I can not be sure. It is true there may have been traitors. We have
them to contend with as well as spies. But our line is intact, and at no
point along it, near enough to it to fire into Paris from an ordinary
gun, can the Germans be found."

"Then it must be an extraordinary gun," suggested Jack.

"It may well be--perhaps it is. Yet, as I said, there may have been
traitors. There may be a gun concealed somewhere closer to Paris than we
dream. But we shall find it, messieurs! Who knows? Perhaps you may be
the very ones yourselves to locate it, for we are depending on you
soldiers of the air."

And it was not long before this talk came back to Tom and Jack with
impressive recollection.

And meanwhile the bombardment of Paris went on, usually during the late
afternoon or early morning hours--never at night, as yet.

Yet with all the frightfulness of which the unscrupulous Huns were
capable, it was impossible to dampen for long the spirits of the French.
Soon they grew almost to disregard the falling shells from the hidden
German gun. Of course there were buildings destroyed, and lives were
lost, while many were frightfully maimed. But if Germany depended on
this, as she seemed to, to strike terror to the hearts of the brave
Frenchmen the while a great offensive was going on along the western
front, it failed. For the people of Paris did not allow themselves to be
disheartened, any more than the people of London did when the Zeppelins
raided them.

Indeed one Paris paper even managed to extract some humor out of the
grim situation. For one day, following the bombardment, a journal
appeared with "scare" headlines, telling about eleven "lives" being
lost. But when one read the account it was discovered that the lives
were those of chickens.

And this actually happened. A shell fell on the outlying section and
blew up a henhouse, killing nearly a dozen fowls and blowing a big hole
in the ground.

There were other occasions, too, when the seemingly superhuman
bombardment was not worth the proverbial candle. For the shells fell in
sections where no damage was done, and where no lives paid the toll.
Once a shell went through a house, passing close to an aged woman, but
not hurting her, to explode harmlessly in a field near by.

And it was with such accounts as these that the Paris papers kept up the
spirits of the inhabitants. Meanwhile the Germans kept firing away at
quarter-hour intervals, when the gun was in action.

"I wonder if there is any chance of us getting in at the game?"
questioned Jack of Tom one night.

"I shouldn't be surprised. As that officer said, they'll have to depend
on the aircraft to locate the gun, I'm thinking."

"And you think we have a chance?"

"I don't see why not," replied Tom. "We've been off duty long enough.
I'd like to get back behind the propeller again, and with a drum or two
of bullets to use in case we sight a Hun plane. Let's go and send word
to our captain that we've had enough of leave, and want to go out
again."

"All right. But what about your father?"

"Well, I don't know what to say," answered Tom. "I'm about convinced
that he wasn't killed, or even hurt, in any of the bombardments of
Paris. But where he is I don't know. I guess, as a matter of duty to
France, I'll have to let my private affairs go and--"

At that instant there sounded an explosion the character of which the
two boys well knew by this time.

"The big gun again!" cried Jack.

"Yes, and they're firing after dark!" added Tom. "This may be just the
chance the airmen have been waiting for--to locate the piece by the
flashes. Come on out and see what's doing!"

Together they rushed from their room.




CHAPTER X

THE "DUD"


Much the same sort of scene was going on in the streets of Paris as Tom
and Jack had witnessed when first the populace realized that they were
under fire from a mysterious German cannon. There was the initial
alarm--the warnings sounded by the police and soldiers, warnings which
were different from those indicating a Zeppelin or aircraft raid, and
then the hurry for cover.

But it was noticeable that not so many of the people rushed for a secure
hiding place as had done so at first.

"They're not so afraid of the big gun as they were," observed Jack, as
he hurried along with his chum.

"No. Though it's just as well to be a bit cautious, I think. The people
of Paris are beginning to lose fear because they see that the German
shells don't do as much damage as might be expected."

"You're right there, Tom," said Jack. "The shells are rather small, to
judge by the damage they do. I wonder why that is?"

"Probably their gun, or guns, can't fire any larger ones such a long
distance, or else their airships can't carry 'em up above the clouds to
drop on the city."

"Then you still hold to the airship theory?"

"Well, Jack, I haven't altogether given it up. I'm open to conviction,
as it were. Of course I know, in theory, a gun can be made that will
shoot a hundred miles, if necessary, but the cost of it, the cost of the
charge and the work of loading it, as well as the enormous task of
making a carriage or an emplacement to withstand the terrific recoil,
makes such a gun a military white elephant. In other words it isn't
worth the trouble it would take--the amount of damage inflicted on the
enemy wouldn't make it worth while."

"I guess you're right, Tom. And yet such a gun would make a big scare."

"Yes, and that's what the Germans are depending on, more than anything
else."

"But still don't you think the French will have to do something toward
silencing the gun?"

"Indeed I do! And I haven't a doubt but the French command is working
night and day to devise some plan whereby the gun can be silenced."

"There go the aviators now, out to try to find the big cannon,"
observed Jack, as he gazed aloft.

Soaring over Paris, having hastened to take the air when the signal was
given, were a number of planes, their red, white and blue lights showing
dimly against the black sky. They were off to try to place the big gun,
if such it was, or discover whether or not some Hun plane was hovering
over the city, dropping the bombs.

As Jack and Tom hastened on, in the wake of the crowd, which was
hurrying toward the place where the latest shells had fallen, again came
a distant explosion, showing that the gun had been fired again.

"Fifteen-minute interval," announced Tom, looking at his watch. "They're
keeping strictly to schedule."

"Night firing is new for the big gun," said Jack. "I do hope they'll be
able to locate the cannon by the flashes."

"It isn't going to be easy," asserted Tom.

"Why not?"

"Because you can make up your mind if the Germans were afraid to fire
the piece at night at first for fear of being discovered, and if now
they are firing after dark, they have some means of camouflaging the
flash. In other words they have it hidden in some way."

"Well, I suppose you're right. But say, Tom, old man! what wouldn't I
give to be able to be up in the air with those boys now?" and Jack
motioned to the scouts who were flitting around in the dark clouds,
seeking for that which menaced the chief city of the French nation.

"I'd like to be there myself," said Tom. "And if this keeps up much
longer I'm going to ask permission for us to go up and see what we can
do."

"Think they'll let us?"

"Well, they can't any more than turn us down. And we've got to get at it
in a hurry, too, or we'll have to report back at our regular station. We
aren't doing anything here, except sit around."

"No, we must get busy, that's a fact," said Jack. "It's about time we
downed some Hun scout, or broke up one of their 'circus' attacks. I've
almost forgotten how a joy stick feels."

A "joy stick" is a contrivance on an aeroplane by the manipulation of
which the plane is held on a level keel. If the joy stick control is
released, either by accident (say when the pilot is wounded in a fight),
or purposely, the plane at once begins to climb, caking its passenger
out of danger.

Once the joy stick is released it gradually comes back toward the
pilot. The machine climbs until the angle formed is too great for it to
continue, or for the motor to pull it. Then it may stop for an instant
when the motor, being heavier, pulls the plane over and there begins the
terrible "nose spinning dive," from which there is no escape unless the
pilot gets control of his machine again, or manages to reach the joy
stick.

"Well, we'll have to get in the game again soon," said Tom. "But what do
you say to taking a taxi? This explosion is farther than I thought."

Jack agreed, and they were soon at the place where the last German shell
had fallen--that is as near as the police would permit.

A house had been struck, and several persons, two of them children,
killed. But, as before, the military damage done was nothing. The
Germans might be spreading their gospel of fear, but they were not
advancing their army that way.

As Tom and Jack stood near the place where a hole had been blown through
the house, another explosion, farther off, was heard, and there was a
momentary flare in the sky that told of the arrival of another shell.

For a few seconds there was something like a panic, and then a voice
struck up the "Marseillaise," and the crowd joined in. It was their
defiance to the savage Hun.

A few shots were fired by the Germans, but none of them did much damage,
and then, as though operating on a schedule which must not, under any
circumstances, be changed, the firing ceased, and the crowds once more
filled the streets, for it was yet early in the night.

The next morning the boys went to report, as they did each day,
expecting that they might be called back to duty. They also found, after
being told that their leave was still in effect, that some of the
aviators who had gone up the night before, to try to locate the German
gun, were on hand.

"Now we can ask them what they saw," suggested Jack.

"That's what we will," assented Tom.

But the airmen had nothing to report. They had ascended high in search
of a hostile craft carrying a big gun, but had seen none.

They had journeyed far over the German lines, hoping to discover the
emplacement of the gun, if a long range cannon was being used. But they
saw nothing.

"Not even flashes of fire?" asked Tom.

"Oh, yes, we saw those," an aviator said. "But there were so many of
them, and in so many and such widely scattered places, that we could
not tell which one to bomb. We did manage to hit some, though with what
effect we could not tell."

"Then the German gun is still a mystery," observed Tom.

"It is. But we shall discover it soon. We will never rest until we do!"

So more and new and different theories continued to be put forth
regarding the big cannon, if such it was. Ordnance experts wrote
articles, alike in London, Paris, and New York, explaining that it was
possible for a cannon to be within the German lines and still send a
shell into the French capital. But few believed that it was feasible.
The general opinion was that the gun was of comparative short range, and
was hidden much nearer Paris than the sixty or seventy-odd miles away,
beyond which stretched the German line of trenches.

Meanwhile Tom, though making careful inquiries, had learned nothing of
his father. He did not feel it would be wise to cable back home, and ask
what the news was there.

"It might spoil dad's plans if I did that," said Tom to his chum, "and
it would worry the folks in Bridgeton to know that I haven't yet seen
him in France. No, I'll just have to wait."

And wait Tom did, though there is no harder task in all the world.

It was one morning, after a night bombardment on the part of the
Germans, that Jack, who had been out for a morning paper, came rushing
into the room where Tom was just awakening.

"Great news, old man! Great!" cried Jack, waving the paper about his
head.

"You mean about a victory?" asked Tom.

"No, not exactly, though it may lead to that. And it isn't any news
about your father, I'm sorry to say. It's about the German gun. A 'dud'
fell last night."

"A 'dud'?" repeated Tom, hardly sensing what Jack said.

"Yes, you know! A shell that didn't explode. Now they have a whole one
to examine, and they can find out what sort of gun shot it. This paper
tells all about it. Come on! Let's go for a look at the 'dud'!"




CHAPTER XI

A MONSTER CANNON


Tom, dressing hastily, read the account in the Paris paper of the fall,
in an outlying section of the city, of one of the German shells that
failed to explode. It was being examined by the military authorities, it
was stated, with a view to finding out what sort of gun fired it, so
that measures might be taken to blow up the piece or render it useless
to the enemy.

"That sounds good to me," said Tom, as they made a hasty breakfast.
"This is getting down to a scientific basis. An unexploded shell ought
to give 'em a line on the kind of gun that fired it."

"The only trouble," said Jack, "is that the shell may go off when they
are examining it."

"Oh, trust the French ordnance experts not to let a thing like that
happen," said Tom. "Now let's go to it."

It was fortunate that Tom and Jack wore the uniforms that had so
endeared them to France, or they might have had difficulty in gaining
admittance to the bureau where the unexploded shell was under process
of investigation. But when they first applied, their request was
referred to a grizzled veteran who smiled kindly at them, patted them on
the shoulders, called them the saviors of France, and ushered them into
the ordnance department, where special deputies were in conference.

"Yes, we have one of the Boche shells," said an officer, who spoke
English fluently, for which Tom and Jack were glad. They could speak and
understand French, but in a case like this, where they wanted a detailed
and scientific explanation, their own tongue would better serve them.

"And can you tell from what sort of gun it comes?" asked Tom.

"It was fired from a monster cannon," was the answer. "That is a cannon
not so much a monster in bore, as in length and in its power to impel a
missile nearly eighty miles."

"Can it be done?" asked Jack.

"It has been done!" exclaimed Major de Trouville, the officer who was
detailed to talk to the boys "It has been done. That is the gun that has
been bombarding Paris."

"But, from a military standpoint," began Tom, "is it--"

"It is utterly useless," was the quick answer. "Come, I will show you
the shell."

He led them to an apartment set aside for the testing of explosives and
working out ordnance problems, and there on a table, around which sat
many prominent French officials, was the German shell--the "dud," as
Jack had called it.

"The charge has been drawn," explained Major de Trouville, "so there is
no danger. And we have determined that the manner in which shots reach
Paris from a distance of from seventy to eighty miles is by the use of a
sub-calibre missile."

"A sub-calibre?" murmured Tom.

"Yes. You know, in general, that the more powder you use, and the larger
the surface of the missile which receives it, the greater distance it
can be thrown, providing your angle of elevation is proper."

The boys understood this much, in theory at least.

"Well," went on the major, "while that is true, there is a limit to it.
That is to say you could go on using powder up to hundreds of pounds in
your cannon, but when you get to a certain point you have to so increase
the length of the gun, and the size of the breech to make it withstand
the terrific pressure of gases, that it is impracticable to go any
further. So, also, in the case of the shell. If you make it too large,
so as to get a big surface area for the gases of the burning powder to
act upon, you get your shell too heavy to handle.

"Now of course the lighter a missile is, the farther it will go, in
comparison to a heavy one with the same force behind it. But you can not
get lightness and sufficient resistance to pressure without size, and
here is where the sub-calibre comes in."

"In other words the Germans have been firing a shell within a shell,"
broke in another officer.

"Exactly," said Major de Trouville. "The Germans have evolved a big gun,
that is big as regards length, to enable the missile they fire from it
to gain enough impulse from the powder. But the missile would be too
large to travel all the way to Paris. So they use two. The inner one is
the one that really gets here and explodes."

"What becomes of the outer?" asked Jack.

"It is a sort of container, or collar, and falls off soon after the
shell leaves the big gun. If you will imagine a sort of bomb shell being
enclosed in an iron case, the whole being put in a gun and fired, you
will better get the idea. The outer case is made in two or more pieces,
and soon after it is shot out it falls away, leaving the smaller missile
to travel on. But here is where the cunning of the invention comes in.
The smaller missile has all the impetus given the larger one, but
without its weight. In consequence it can travel through eighty miles of
atmosphere, finally reaching Paris, where it explodes."

"Wonderful!" exclaimed Jack.

"And yet it is merely the adaptation of an old theory," went on the
major. "We have known of the sub-calibre theory for years, but it is not
practicable. So we did not try it. The cost is too great for the amount
of military damage done. And this shell, as you will see, is composed of
two parts, each with a separate explosive chamber, each containing, as
we discovered, a different sort of explosive. In this way if one did not
go off, the other would, and so set off the one that failed. It is very
clever, but we shall be more clever."

"That's right!" chimed in a chorus of fellow officers.

"We'll find the gun and destroy it--or all of them if they have more
than one, as they probably have," went on the major.

He showed the boys where the shell had chambers for the time fuses to
work, much as in a shrapnel shell, which can be set to go off so many
minutes or so many seconds after it reaches its objective point.

"And so the great question is settled by the failure of this shell to
explode," went on the major. "As soon as we saw it, and noted the
absence of the rifling groove marks, we knew it must have been a
sub-calibre matter. The rest was easy to figure out.

"Some of us thought there might be a big airship, stationed high above
the clouds, dropping bombs. Others inclined to the theory of a double
shell; that is, after one had been fired from the cannon it would
travel, say, half way and then explode a charge which would impel
another shell toward Paris. A sort of cannon within a cannon, so to
speak. But this is not so. Nor did the theory of a shell with a sort of
propeller device, like that of a torpedo, prove to be right. It is much
simpler--just sub-calibre work."

"And what is going to be done about it?" asked Tom. "I mean how can the
monster cannon be silenced?"

"Ah, that is a matter we are taking up now," was the answer of Major de
Trouville. "I fancy we shall have to call on you boys for a solution of
that problem."

"On us?" exclaimed Jack.

"Well, I mean on the aircraft service. It will be their task to search
out this great German cannon for us, to enable our gunners to destroy
it. Or it may be that it will have to be bombed from an aeroplane."

"That's the task I'd like all right!" cried Tom, with shining eyes.

"Same here!" echoed Jack. "Do you suppose we'll get a chance?" he asked
eagerly.

"You may," was the reply. "It may take all the resources of our airmen
to destroy this terror of the Germans. But it will be done, never fear!"

"_Vive la France!_" cried his companions, and there was a cheer in which
Tom and Jack joined.

And so a part of the secret was discovered. It was a monster cannon that
was devastating Paris. A great gun, the construction of which could only
be guessed at. But it must be destroyed! That was certain!




CHAPTER XII

FOR PERILOUS SERVICE


Tom and Jack spent some little time looking at the strange German shell.
It was of peculiar construction, arranged so that the two explosive
charges would detonate together or separately, according as the
mechanism was set.

But in this case it had failed to work, and the shell, falling in a bed
of soft sand, near some new buildings which were going up, had not been
fired by concussion, as might have happened.

"And it was just French luck that it didn't go off," observed Jack.

"That's right," agreed Tom. "If they hadn't had this whole shell to
examine they wouldn't know about the big gun."

So all the theories, fantastic enough some of them, about great airships
hovering over the beautiful city, and dropping bombs from a great
height, were practically disproved.

"Well, now that you have decided it is a big German gun, the next
question is, where is it and what are you going to do about it?"
observed Tom, for he and Jack had been made so much of by the French
officers that they felt quite at home, so to speak.

"Ah, messieurs, that _is_ the question," declared Major de Trouville.
"First to find the gun, and then to destroy it. The first we can do with
some degree of accuracy."

"How?" asked Tom.

The major went to a large map hanging on the wall of the room. It showed
the country around Paris and the various lines as they had been moved to
and fro along the Western front, according as the Germans advanced or
retreated.

"You will observe," said the major, "that by describing an arc, with
Paris as the center of the circle, and a radius of about seventy-five
miles, you will include a small sector of the German trenches. Roughly
speaking this arc will extend from about Hamegicourt to Condé, both
within the German lines, I am sorry to say. Now then, somewhere in this
arc, or perhaps back of it, the German gun is placed. Anywhere else
where it would be possible for such a monster engine of war to be
erected, would bring it too close to our batteries.

"So that gives us the comparative location of the gun," went on the
French officer. "But the next question is not so easy to settle--how to
get rid of it. As I said, I think we shall have to depend on you
airmen."

"Well, we're for the job!" exclaimed Tom.

"I know you are. And it may fall to you, or to your friends. I will talk
of that later."

"Have you been able to get any idea of the kind of gun it is, or why it
fires at fifteen minute intervals?" asked Jack.

"We have been able to get no really reliable information save that which
we deduce by our observations of this shell and from what we know of the
location of our own and the German lines," the Major went on. "Up to now
our airmen have not been able to penetrate far enough without being
attacked, and such few as did get well over toward the Rhine could make
out nothing. I have no doubt the gun is well camouflaged."

"And is it true that it doesn't fire at night because the Germans are
afraid the flashes will be seen?" asked Tom.

"That may have been the reason at first, but they have fired at night,
of late, so they must have some way of concealing the flashes, or
perhaps setting off other flashes at the same time so as to confuse our
scouts."

"It's going to be some job," murmured Jack.

"You said something," agreed his chum.

They remained talking a little longer, and some of the officers who
knew the reason for Tom's visit to Paris, expressed regret that he had
no information as yet about his father.

"But take heart," one told him. "He is not dead, or we should have heard
of it. Of course he may have fallen into the hands of the Germans, and
then we would not know for some time."

"He may have been caught," agreed Tom. "While Tuessig is out of the game
on account of his injuries, he may be able to direct Potzfeldt, and that
scoundrel would have good reason for trying to get revenge on us."

"Ah, yes, I heard about your rescue of the young lady and her mother,"
said the major. "It was a brave deed."

"Oh, any one could have done it," said Tom, modestly.

"And have you seen them since they came to Paris?" the major proceeded.

"No, but I wish we could find them!" burst out Jack, and then he blushed
at his impetuosity, while Tom murmured something about "Bessie," and
Jack promptly told him to hold his tongue.

"Perhaps you may meet them sooner than you expect," went on the French
officer.

"Now I wonder what he could have meant by that?" asked Jack, as he and
his chum went out, after a final look at the German shell. "Does he
know where they are?"

"It wouldn't be surprising, seeing that Mrs. Gleason is probably in Red
Cross work, and Bessie may be helping her. We should have looked them up
before," went on Tom. "But what with searching for my father, and the
excitement about the bombardment, I really forgot all about them."

Jack did not say whether he had or not, the chances being that he had,
more than once, thought of Bessie Gleason.

During the next two days the monster cannon continued to shoot shells at
intervals into Paris. Some did considerable damage, as any shell would
do in a great city, and many unfortunates were killed. But there was no
reign of terror such as, undoubtedly, the Boches hoped to create. Paris
remained calm, and there were even jokes made about the cannon. It was
called a "Bertha" and other names, the former referring to Bertha Krupp,
one of the owners of the great German ordnance works.

Word was given out that the French gunners on the front were trying to
reach the big gun with their missiles. But as they were firing blindly
it could not be said what havoc had been wrought.

"But, sooner or later, we'll get the range, and get within striking
distance," said one of the French officers. "Then we'll show them a
trick or two."

"Have the aviators done anything toward trying to find the gun?" asked
Tom. "I mean anything more."

"We are perfecting our plans for the flying corps," was the answer.
"Perhaps you shall know more in a few days."

"Well, I hope we'll be here when the fun begins," said Tom, grimly.
"We've got another extension of leave, and I'm going to ask the police
now, to co-operate with the military in seeking my father."

"I think that will be a wise plan. We will give you all the help we
can."

But the quest for Mr. Raymond seemed a hopeless one, and as no
confirmation could be had of his death or injury, the idea gradually
became fixed in the minds of Tom and Jack that he had been made a German
prisoner.

"If that is so, and I can get any trace of him, I'll go over the Rhine
to get him back," snapped Tom.

"And I'll go with you!" declared his chum.

It was a few days after they had inspected the German "dud," and the
boys were wondering what new developments might take place, the shelling
of Paris meanwhile continuing at intervals, that one evening the boys
were visited in their lodgings by Major de Trouville.

"Is there any news?" eagerly asked Tom, for he guessed that the French
officer would not be paying a merely social call. Those were the
strenuous days when such things had passed.

"Well, yes, news of a sort," was the answer. "But what I came to find
out was whether you were so taken with these lodgings that you could not
be induced to move."

"To move!" exclaimed Jack.

"Yes. Have you found anything unhealthful here?"

"Why, no," replied Tom, wonderingly. "We like it here. The landlord
couldn't be nicer, and we're in a good location."

"Nevertheless, I fear I shall have to ask you to change your quarters,"
went on the major, and by the quizzical smile on his face the boys
guessed that there was something in the wind.

"Let me ask you another question," went on the French officer. "Have you
been annoyed since you have been here?"

"Annoyed? How?" inquired Tom.

"By unwelcome visitors, or by strangers."

The boys thought for a moment.

"There's one chap who lives in the same building here, whom we've seen
on our staircase several times," said Jack, slowly. "Once I saw him
pause at our door with a key, as though he were going to enter, but he
heard me coming, and, muttering that he had taken too much wine and was
a bit hazy in his memory, he went on upstairs."

"I thought as much," the major said. "Was the man you speak of familiar
to you?"

"No, I can't say that he was," replied Jack, and Tom nodded his
acquiescence. "I never saw him before."

"Oh, yes you have," and the major smiled.

"I have? Where?"

"On the train, coming into Paris."

"You mean the German spy?" cried Jack.

"The same," answered the Frenchman. "That's just what he is, and he is
spying on you. Now, in view of what is going to happen, we don't want
that to go on. So I have come to ask you to change your lodgings, and I
think I can take you to one that will be most agreeable to you both."

"But what does all this mean?" asked Tom. "Is there----"

"There is 'something doing' as you say so picturesquely in the United
States," interrupted the major. "I have come to tell you that you are to
undertake a most perilous mission!"




CHAPTER XIII

THE SPY


Tom Raymond and Jack Parmly looked first at one another and then at the
major. He had been smiling at their wonderment, but he was now serious,
and regarded them gravely.

"Do you mean we have to do something to help catch this spy?" asked Tom.

"I'd like a hand in that!" exclaimed Jack. "I saw him first--he's my
meat!"

"Well, get him if you can, boys," said the Frenchman. "But I did not
come here to talk so much about him as about yourselves. The spy is a
danger and a menace, but we know him and if he goes too far we can put
out our hands and drag him back.

"No, what I referred to is more dangerous than merely trying to catch a
spy at his sneaking work. I will tell you." The major suddenly left his
seat near the window of the boy's room, and quickly opened the door
leading to the hall. The passage was empty.

"I rather thought there might be an eavesdropper," the major explained.
"I was followed here, though I don't believe the spies know my mission.
However, it is best to be careful. With your permission I'll pull down
the shade. There may be spies stationed across the street who, with
powerful glasses, might look through the window and gather something of
what we say by reading our lips. It has been done."

"The Germans don't leave much untried," commented Tom. "But what is it
you want us to do, if it isn't trying to trail the spy?"

The major motioned them to draw closer to him, and then, leaving the
door into the hall open, so that he could note the approach of any one,
he whispered:

"You are to be two members of a picked company of air scouts who are to
go out, discover the big German gun, and destroy it!"

"Whew!" whistled Tom, after a moment of thought during which he and Jack
exchanged quick glances.

"Well?" asked the officer. "How does that strike you? I believe that is
another of your captivating terms?"

"It's all to the good!" exclaimed Jack. "What say, Tom? We'll take that
on, won't we?"

"Well, I should say!" was the enthusiastic rejoinder. "When do we start
to--"

"Hush!" cautioned the major. "Not so loud. Though we have taken every
precaution, there may be spies unseen by us. We had better talk no more
about it here."

"Then let's go to our new lodgings, if we are to move," suggested Tom.
"Will it be safe to talk there?"

"I think so," the major said. "At least you will be among friends. Not
that your landlord here is not a true Frenchman; but he can not control
the actions of those to whom he lets lodgings. You will be better where
you are going. Then you accept the mission?" he asked in another
whisper.

"Sure thing!" answered Tom, while Jack nodded his assent. "The sooner
the quicker!"

"I do not quite get that," the major confessed with a smile. "But I
think I gather your meaning. Now if you will proceed to this address,"
and he handed Tom a small slip of paper, "you will find a comfortable
lodging, and you will be among friends."

"How soon can we start on--on this mission?" asked Tom.

"It will be better not to refer to it directly," the officer said. "Talk
as little about it as you can. But you shall go as soon as the
arrangements can be made. You will be notified."

"And what about seeing our friends--Mrs. Gleason?" asked Jack.

"Are you sure its _Mrs._. Gleason you want to see?" inquired Tom.

"Oh, cut it out!" advised Jack with a blush.

"You may see them soon now," the major told him with a smile. "And I
hope you'll soon have good news of your father," he added to Tom.

"I hope so, too. The suspense is telling on me."

"I should think it would. Now don't leave this bit of paper about with
the address of your new lodgings on. Better commit it to memory, and
then destroy the sheet. We want, if possible, to prevent the spy from
knowing where you have gone. I will call a taxicab for you. You can be
packed soon, I suppose?" he questioned.

"Within a half hour," answered Jack. "But say, won't that spy be on the
watch, and won't he learn from the taxicab driver where we have gone?"

"Not from _this_ taxicab driver," was the smiling answer. "He is one of
our best secret service men. But treat him as you would an ordinary
chauffeur. You may even give him a tip, and he will not be offended,"
and once more the major smiled.

Tom and Jack, having made sure they remembered the address given them,
destroyed the paper, and then proceeded to get ready to move. Meanwhile
Major de Trouville took his departure, promising to keep in
communication with the Air Service boys.

Punctual to the half hour a taxicab appeared at the door. The boys
obeyed the instructions they had received, and looked out to make sure
the spy was not on hand. If he was, he was well concealed, for they did
not see him.

"Though I suppose he's somewhere around," said Jack.

"Well, maybe we can fool him," suggested Tom. "We're going quite on the
other side of Paris."

They made sure that, as far as could be told by observation, there was
no one resembling the spy around the place or in the street in front,
and then got into the cab with their baggage. The chauffeur seemed not
to know them, but Tom thought there was just the slightest wink of one
eye, as though to indicate that the game was going well.

Their cab was driven out along the Boulevard Ragenta, past the Gare du
Nord, and across the Boulevard de Rochechquart to a small street running
off the Rue Ramey, and there the cab stopped in front of a small but
neat-looking house.

"Quiet enough neighborhood," remarked Jack, as they got down, and Tom
tipped the cabman for the benefit of any spies who might be looking.

"Yes, I guess we can get some sleep here, if the big gun doesn't keep us
awake," agreed Tom.

On the way they had passed several places where the havoc of the
"Bertha" was noticeable.

Tom and Jack seemed to be expected, for the porter, who came down to get
their bags, did not seem at all surprised to see them. He bade them
follow him, and a little later, the cab having chugged off, the boys
were settled in a pleasant room, a smiling landlady coming in to see if
they wanted anything, and to tell them they could have meals with her at
certain hours, or they might dine out as they pleased.

"Your friends will be here shortly," she added.

"Our friends?" questioned Tom.

"Yes," with a nod and a smile. "I was told to say they would be here
shortly after you arrived."

"Oh, I guess she means the major and some of the officers will come to
see how we are situated, and to tell us more about--the big stunt," said
Tom in English to his chum, assuming that "big stunt" would sufficiently
disguise to any listening spies, if such there were, the real object
that lay before them.

"I suppose that's who she means," agreed Jack, as the landlady, who gave
her name as Madame Reboux, withdrew.

The boys were busy unpacking their few belongings, for they had not
brought much to Paris, not intending to stay long, when they heard
voices in the hall outside their room. And at the tones of a certain
voice Tom and Jack started and looked at one another.

"Listen!" exclaimed Tom.

"If I wasn't afraid you'd say I was dreaming, I'd say I knew that
voice!" murmured Jack.

"I'd say the same," added Tom.

"Who would you say it was?" his chum challenged.

"Well, for a starter--"

He paused, for the voice sounded more plainly now, and it said:

"Yes, this is the right place, Mother. Oh, do you think the boys are
here yet?"

"It surely will be a pleasure to meet them again," said another voice,
evidently that of a woman, the other having been a girl's.

"I hope they won't have forgotten us," the girl went on, and at that
Jack could no longer keep quiet. He rushed to the door, opened it, and
cried:

"Bessie! Is that you?"

"Oh, it's Jack! Mother, here's Jack!" cried the girl, and she and her
mother were soon shaking hands with Tom and Jack.

"So, you two were the friends we were soon to see!" exclaimed Tom, as he
placed chairs for Mrs. Gleason and her daughter. Or, to be exact, Tom
placed a chair for the mother, while Jack got one for Bessie.

"Yes, we were told you would be here," said Bessie's mother. "We did not
know you were in Paris until we received word that it would be better
for us to change our lodging and come here."

"The same word we received," said Jack. "Say, it's working out mighty
queer, isn't it, Tom?"

"Yes, but very satisfactorily, I should say. Things couldn't be nicer.
How have you been?" he asked, for he had not seen the girl nor her
mother since the sensational rescue from the perfidious Carl Potzfeldt.

"Very well indeed," answered Mrs. Gleason. "Both Bessie and I have been
doing Red Cross work. But isn't that great German gun terrible? Oh, how
it has killed and maimed the poor women and children! The Huns are
fiends!"

"I quite agree with you," said Tom, Jack meanwhile talking to Bessie.
"But it isn't doing them the military good they thought it would, and,
if all goes well, it may not very long do them any service at all."

"You mean--" began Mrs. Gleason.

But just then Bessie, who had arisen to go to the window to view the
street, turned back with a start, and grasped Jack's hand.

"Look! Look!" she whispered, and through the curtains she pointed to a
man on the opposite side of the way.

"Do you know him?" asked Jack.

"Know him? Yes, to my sorrow."

"Who is it?" asked Tom.

"The spy!" exclaimed Jack. "The man we saw in the train, and the same
fellow who tried to get into our lodgings. In spite of our precautions
he has found out where we are."

"I'm not so sure of that," said Tom. "He may not be here for any
particular purpose. But do you know him too, Bessie?"

"Yes," the girl answered. "He was in the château where mother and I were
held prisoners by Potzfeldt. He is a tool in the pay of that spy, and a
spy himself!"

"Then we ought to do something!" exclaimed Jack, and he started to rush
from the room.




CHAPTER XIV

WITH COMRADES AGAIN


"Hold on! Wait a minute!" exclaimed Tom, as he caught hold of his chum.
"Where are you going?"

"Out to give warning to a policeman or to some army officer about that
spy!" exclaimed Jack. "We know him to be such, and now, with Bessie's
word that he was with Potzfeldt, it's enough to cause his arrest."

"Yes, maybe it is," agreed Tom, who was a bit more cautious than his
impetuous chum. "But if we do that we may spoil the plans of Major de
Trouville. Better let matters take their course, Jack. That spy may not
know we are here, and again, he may. But if he doesn't, rushing out now
would be sure to give the secret away. As it is, there is a chance we
may keep it."

Jack, caught midway in his impetuous rush from the room, stood
reflectively. What Tom had said to him appeared to make an impression.
Then Bessie added her words of advice.

"Yes, Jack," she said, "I think it would be rather rash to go out now
and confront that man, or start a chase after him. I know I'm not as
experienced as you two famous birdmen," she went on with a smile, "but
I've been through some terrible experiences, as almost every girl has in
this war zone, and I can do more thinking than I used to. Don't you
think it would be wise to wait, Mother?"

"Yes, Bessie," answered Mrs. Gleason, "I do. Our good friends in the
military service who told us to come here, must have had some object.
Perhaps it was connected with this same man who was so unkind to us in
the château, and who was certainly a tool of that man I trusted once,
but never will again--Carl Potzfeldt!" and she shuddered as she thought
of what she had gone through.

"Let him go," she said to Jack. "Perhaps it is just a coincidence that
he is passing just as we arrive. Our departure from our last lodgings
was made secretly."

"So was ours," said Tom. "And yet I don't see how that spy found us so
soon."

"It is that which makes me think it is accidental," observed Mrs.
Gleason. "It would be very unwise now to go out, I think."

"All right, then I'll stay in," said Jack with a smile. "Especially as I
have such good company. Tell me," he went on, "are you and your mother
going to board here?" he asked Bessie.

"Yes," answered Mrs. Gleason. "And though we were told we would meet
friends here we could not guess it would be you brave boys."

"Spare my blushes!" laughed Tom.

"Same here," added Jack.

"But what brings you to Paris?" asked Bessie. "I thought you boys were
engaging in combats above the clouds."

"We have been fighting, though not during the last two weeks," said Tom.
"I had word that my father had come over here, but he never communicated
with us, and we came to Paris to look him up. So far we haven't
succeeded in finding him," and he gave the details of the visit of
himself and his chum to the capital, telling of their first experience
during the firing of the big gun.

Bessie and Jack, who seemed to have much to say to one another, peered
from behind the curtains out of the window now and then, and Jack at
last reported that the spy had passed on, after stopping, apparently, to
purchase some fruit at a stand on the street.

"I don't believe he knew we were here," said Bessie.

"Well, it won't do to take any chances," observed Tom. "However, we were
not told to remain under cover, so I suppose we can go out when we
like."

"Better wait until we get some word from the major," suggested Jack, who
was getting some of his chum's caution.

All decided this was best, and the boys spent the rest of the afternoon
in getting their room to rights, Mrs. Gleason and Bessie doing the same
in their apartment. Mrs. Gleason had temporarily been relieved from Red
Cross work to recuperate, she said, as she had been under a great
strain.

Toward evening Major de Trouville, or "Trouville," as he democratically
liked to be called, arrived, and when told of the sight in the street of
the spy, who turned out to be the same man who was one of the captors of
Bessie and her mother, the officer said:

"I am not surprised. In fact I rather looked for that, and it is one
reason why I wanted to get you four together so you could see the man at
the same time.

"There is now no doubt as to his intentions, and the fact that he was
here so soon after you arrived proves that there is a 'leak' somewhere.
We suspected as much, and I think I know where it is. It is good
information to have. Well, boys, did I surprise you?" he asked, smiling.

"You did, indeed, but it was a pleasant surprise," said Jack.

"But when are we going to be allowed to do something to silence that
monster cannon?" asked Tom. "It's pleasant to be here, but we are not
forgetting there is work to do."

"Nor would I have you forget," said the major. "A number of persons were
killed to-day by fire from the long-range gun. We believe, now, that
there are two or three of them, as the shots come at closer intervals.
It is imperative that something be done, and so I have brought you
orders."

"Good!" cried Jack.

"That sounds like business!" commented Tom.

"In regard to your father," went on the major, addressing Jack's chum,
"we will be on the watch for him, or any news of him, and, no matter
where you are, unless you are captured by the Germans, you shall be
informed as soon as possible."

"Is there any chance of being made prisoners?" asked Jack, and it might
be noted that he did not use the word "danger."

"There is always that chance for an airman," replied the major. "But
when I add that it may be possible that one or both of you will take a
flight over the Rhine, you can judge, with the hold Germany has on
French possessions, what the danger is."

"Over the Rhine!" exclaimed Tom. "Why, that's a flight of two or three
hundred miles from Paris."

"Yes, but with the new type of Italian plane which you may use, it is
not impossible in a single flight," said the major. "However, we will
talk of that later. Just now I have come to tell you that you are to
rejoin your comrades at the Lafayette Escadrille for a time. There
arrangements will be made for the perilous venture I spoke of--the
silencing of the big guns that are bombarding Paris. I wish you all
success, young gentlemen."

"Thanks," murmured Jack.

"We consider it an honor to be picked for such duty," added Tom. "Are
any others going to be in the game?"

"Oh, yes. We shall need a picked corps of the best airmen we have,
French and Americans, and it will be no easy matter then. The Germans
have probably been planning this for a long time, and they, no doubt,
have taken every possible precaution against surprise or failure. But
with the help of you brave Americans we shall win!"

"That's right!" chimed in Bessie. "Oh, how I wish I were a man!" and she
looked enviously at Jack and Tom.

The major gave Bessie and her mother some instructions in regard to
their actions should the spy come back, and then told Tom and Jack to
prepare to leave Paris the next night.

"Report to your former camp," he said, "and there you will find further
instructions waiting for you."

"Well, then as we have to-night, our last one free, let's go to some
entertainment," suggested Tom to Bessie and her mother. "We can have
supper afterward--not much of a celebration, for these are war times and
it won't do to rejoice too much. But we ought to commemorate this
meeting somehow."

"That's right!" agreed Jack.

So they went to a little play and had supper afterward in a quiet
restaurant. That is, it was quiet until a sudden explosion a few blocks
away announced the arrival of another German shell from the big gun, and
then there was excitement enough.

Fortunately, however, the shots did little beyond material damage, no
one being killed. At the same time, however, there appeared some German
planes over Paris, doubtless to observe the effect of the dropping of
the long-distance shells, and naturally the French airmen went up to
give them combat.

The great searchlights began to play, picking out the hostile craft, and
making them targets for the machine guns of the intrepid Frenchmen, and
more than one Boche never got back over his lines again, while several
Frenchmen found heroes' graves on the soil they had died to defend.

"Oh, if we were only up there helping," said Tom, as he and his friends
watched.

"We shall be there very soon," murmured Jack. "And it can't be any too
soon for me."

The tide of battle turned in favor of the French, the Hun planes
withdrawing as the fire got too hot for them. And soon after that the
long-range gun ceased firing.

It was rather a "pull" for Tom and Jack to say good-bye to Bessie and
her mother in Paris, but they knew they had to do their duty. Nor would
Mrs. Gleason and her daughter have kept the boys back for the world.
They realized that the Air Service boys were helping to make the world
safe for democracy, as they themselves were doing in their way.

And so Tom and Jack, their mission to Paris, which was the discovery of
Mr. Raymond, having failed, went back to the hangars, there to be
welcomed by their comrades in arms.

They arrived one morning, just after some planes from a bombing
expedition over the German lines returned.

"What luck?" asked Tom of a pilot with whom he had often flown.

"The best, as regards the damage we did," was the answer. "We blew up
several ammunition dumps, and put one railroad center out of business
for a time. But Louis didn't come back," and the man turned aside for a
moment.

"You mean your brother?" asked Jack, softly.

"Yes."

"Perhaps he is only captured," suggested Tom.

"No, his machine caught fire. They got his petrol tank. It's all up with
him and La Garde. But we had our revenge. We sprayed the machine that
got them until there was nothing left of it. And I'm going out again
to-day in a Nieuport. They'll pay a price for Louis!"




CHAPTER XV

THE PICKED SQUADRON


"All ready, Jack?"

"Just a moment, Tom. I want to go over my struts and wires to make sure
everything is taut. I don't want any accidents."

"That's right. Got plenty of ammunition drums?"

"All I can carry. I've got some tracer bullets, too."

"That's good. Glad you reminded me of them. I must put in a stock. The
last time I went up I wasted a drum before I got my man."

Tracer bullets for aircraft guns, it might be observed, are balls of
fire which enable the pilot to see the course his machine gun bullets
are taking, so he may correct his fire.

"Well, how about you now?" asked Tom, as he added these useful supplies
to his ammunition.

"I guess we're ready to start," replied Jack.

They climbed into their machines, each pilot using a single-seat,
swift-flying craft, equipped with a Lewis machine gun. The squadron was
going out on patrol duty, and each pilot was to observe what he could
behind the German lines, and come back to report--that is if he did not
happen, as was too often the case, to be bagged by a German flier. The
small, swift machines did not carry the wireless outfit, and no reports
could be sent back to headquarters save those the pilot himself came in
with.

There was a rattle and a roar as the motors of the ten machines started,
and then over the ground they went, "taxi fashion," to get the necessary
speed to rise into the air. A moment later all went aloft, and were
headed toward the German lines.

Tom and Jack kept as close together as was safe, but it is dangerous for
two aeroplanes to approach too closely. If they do, and are not under
good control, there may be a suction created that will cause a
collision.

"Well, I hope I get one to-day," thought Tom, as he manipulated his "joy
stick," so as to send his plane up on a sharp slant. "I want to make
good, and then I'll have so much better chance to get after that German
gun." And the same thought was in Jack's mind.

The squadron was to remain aloft on a two-hour patrol, that is unless
something should occur to make it advisable to remain up longer. The
keen eyes of Tom and Jack, as well as those of their companions of the
air, were searching for signs of the Hun planes. As yet none were in
sight, but it would not be long before they would come out to give
battle.

Whatever else may justly be said about the Germans, their airmen are no
cowards, and, when conditions are favorable, they seldom decline a
chance to combat above the clouds, or lower down. So it could easily be
guessed that when Tom, Jack and the others found themselves over the
German lines that the Boches would be out in force.

Somewhat off to the left Tom caught sight of a captive German balloon,
looming through the mist, and as it is always the desire of a French
flier to destroy one of these, thus preventing the observer from sending
by wireless news of the Allied front, he started for this enemy. Jack
saw his friend's act, and, desiring to aid, turned his machine in the
same direction.

But they had not gone far before they observed a number of black specks
in the sky over the German lines.

"The Huns are coming," reflected Tom. "Now for some hot work."

And it came to him, to Jack, and the others, almost before they realized
it. Tom never got a chance to attack the balloon he hoped to force to
descend or to set on fire, for his attention was taken up by two German
machines, which, separating from the others, headed straight for him.
The lad gave one glance in the direction of Jack, and noted that a
single Hun craft was about to engage with his chum.

"It's a regular German circus," thought Tom, referring to the number of
hostile craft. "They delight to go out in numbers."

By this time the battle in the air had begun. It was a fight above the
clouds, for both the French and the German machines were flying high,
and had gone up above the bunches of fleecy vapor that now hid the
ground from sight.

Tom headed straight for one of the Hun machines, seeking to get above
it, always a point of vantage in an air battle, and as he rushed on he
realized that his machine was being hit by bullets from one of the Hun
guns.

Each bullet, as it struck, made a loud noise, as it punctured the
tightly-drawn linen that covered the wings. But Tom knew that his craft
could stand a number of such holes, if only the struts, the supports,
and the guy wires were not broken. He had no time, now, to note what
Jack or his comrades were doing, for his whole attention was taken up
with the two Hun machines engaging him.

One seemed to be more skillful than the other, and to this one Tom gave
his attention first. He emptied a stream of bullets full into this
flier's craft, noting, after the first few bad shots, which he could
tell by the tracers, that he had perfect range.

Guiding his craft with one hand and his feet, Tom worked the Lewis gun
with his other hand, and he had emptied a whole drum at the daring Hun
before he had the satisfaction of seeing the machine crumple up. Tom's
bullets had struck some part that had caused the wings to collapse, and
the airman went down to earth, his craft out of control.

But matters were not to go easy with the American. The other German was
now in a better position for getting Tom than the latter was for potting
him, and Tom felt a stream of bullets flying around him. One chipped his
gun, and another grazed his cheek, the close call making his heart stand
still for a moment. But he never faltered.

"I've got to get above him," Tom thought fiercely.

He made a risky spiral turn to one side, and began to mount, seeking to
get in position to fire to better advantage. It was touch and go for a
while, and he felt, rather than heard, his craft receive several
bullets.

"If only the gasolene tank isn't hit," thought Tom.

But good fortune in this respect was with him, and he got in a position
where he could point his machine (and the gun at the same time, for this
is how the guns are aimed in the single aircraft) at the Hun flier. And
then Tom sent forth a rain of bullets.

For a moment they seemed to have no effect, and yet Tom knew he had shot
straight. Then, even while he felt a sharp pain in one hand, showing
that he had been hit, he saw the other machine start down in a spinning
nose dive. That meant he was going downward head first, and at the same
time spinning around like a top.

This spinning nose dive may be intentional or accidental--that is, with
the machine in control, or out of control. The spinning nose dive was
discovered by accident, but is now part of the regular flying features,
and is often used by aviators to escape from an enemy.

It is almost impossible to hit a plane doing a spinning nose dive, and
if an aviator is over his own lines he may be able to come out of it
before he reaches the ground, and so be safe. Many German planes have
escaped in this way, and often a French airman has thought he has sent
his enemy down disabled, when, as a matter of fact, the other has merely
adopted this ruse to get away.

"Well, I don't know whether I got him, or whether he got frightened and
went down to fool me," thought Tom. "Anyhow they're both out of the way,
and I can go after the balloon."

But Tom could not, for two reasons. One was that the wound in his hand
was bleeding profusely, and he knew it ought to be attended to before he
was incapacitated. Another was that the balloon was being hauled down,
and as more French planes were in the air now, making a number superior
to the Huns, the latter turned tail and retreated.

It was inadvisable to follow them over their own lines now, and the
squadron, or what was left of it, began to retreat. Tom noted the
absence of three of the French planes, and among the missing was Jack's.

"I wonder if they got him," Tom mused, his heart becoming like lead. His
eyes sought the air about him, but Jack's machine, which carried a
little United States flag where it could easily be seen, was not in
sight.

It was impossible to get any information up in the air. Tom would have
to wait until they got back to the aerodrome. And he put on speed to get
there the sooner, in order to end his suspense.

"And the other brave fellows--I wonder what happened to them," mused
Tom. In his worry over the fate of Jack and the others he scarcely
minded the pain in his hand.

He made a good landing, but being rather weak and faint from loss of
blood, he scarcely heeded the congratulations of his comrades, who had
received word, by telephone from the front, of the fate of some of the
Hun machines. "Where's Jack?" Tom gasped, while a surgeon was putting a
bandage on his hand.

"Right here, old scout!" came the unexpected answer, and Jack himself
stepped out from amid a throng of airmen. "Why didn't you wait for me?"
Jack went on. "I was coming back."

"Coming back? Did you come down safely?" asked Tom, beginning to feel a
little better now. Then Tom realized the futility of his question, for
was not Jack there in the flesh?

"Of course I came back, old scout," was the answer. "I had hard luck,
though, but I'd have gone up again if they'd only waited for me."

"What happened?" asked Tom.

"Oh, just after I potted my man--or at least sent him down out of
control--I got a bullet through my gasolene tank. Luckily it didn't set
the petrol on fire, but I knew I'd better not take any chances. I tried
to plug up the puncture with some chewing gum, but it wouldn't work.
Guess the gum they sell now hasn't as much old rubber boot stock in it
as it used to have. Anyhow it was leaking like a sieve, and I had to
head for our lines."

"Tough luck!" consoled Tom. Jack did not add that he had, as soon as he
landed, got into another machine, and was about to go back and join his
comrades when they returned, having practically won the battle above the
clouds.

Congratulations were extended to the members of the squadron, who
accepted their honors modestly enough, as was characteristic of them.

Then, after Tom's wound had been dressed, and he and Jack were talking
over the events of the day, there came a communication from the
commander of the air division in that sector. It was an order calling on
certain men to report at once for special duty. A picked squadron was to
be detailed for a hazardous enterprise, it was said.

"And our names are there!" cried Jack. "Tom, old man, we're going!"

"But where is it?" asked another American flier named Boughton. "What's
the game?"

Knowing the secret would be safe with him Tom said:

"We're going to pot the big German cannon that's bombarding Paris!"




CHAPTER XVI

MISSING


News of the shelling of Paris by the long-range gun had, of course, been
received at the aerodrome, though there had not, as yet, many details
come in. Tom and Jack, as the latest arrivals from the big city, were
called upon to tell all they knew, and they related their experiences in
the raids, and also told about the various theories of the big gun.

"But how are we going to find it?" asked. Boughton. "It's easy enough,
of course, for our squadron to go out with a lot of bombs. But where are
we going to drop 'em?"

"Oh, we're to go to Paris for further instructions before starting on
the quest," said Tom, who had made some inquiries about the orders
concerning the picked squadron.

"And they may have discovered its location by this time," added Jack.
"We know about where it is--somewhere in the sector between Hamegicourt
and Condé. The rest ought to be easy."

"Not so easy as it sounds, my friends," put in a French flier. "I know
that region. It is a big one; and the Germans no doubt have their gun
well camouflaged. It will not be easy."

"But we'll get it!" asserted Tom.

"Naturally," said the Frenchman, as if that was all there was to it.

Tom's wound was painful, but not dangerous, though it would keep him on
the ground for a day or two. Though, as a matter of fact, none of the
members of the picked squadron was allowed to go aloft after the orders
came detailing them for work in connection with the monster cannon.
Their places were taken by others who were sent for, some being new
fliers who were burning to make a name for themselves.

Besides Tom and Jack, in the picked squadron there were Boughton,
another American, Cerfe and Tierse, two intrepid Frenchmen, and Haught,
an Englishman, who insisted, but with little success, that his name be
pronounced as though spelled "Hoo."

These six were to be depended on to find and destroy the German
cannon--all of them if there were more than one, as was likely. And to
this picked squadron other members would be added as need arose. All six
were skillful fliers, and brave men of the air, as may easily be
guessed. They were to use whatever type of machine they liked best--the
single seaters, the great bombing planes, and, it was even said, one of
the immense Italian fliers. This last was a craft capable of carrying
several men and a quantity of supplies and ammunition.

Very soon, then, Tom Raymond and Jack Parmly were on their way to Paris
again, accompanied by their comrades, and all would soon be engaged in
the difficult and perilous task of finding the new German long-range
cannon.

"I suppose you'll make another attempt to find your father?" suggested
Jack to his chum, as they rode in on the train.

"Indeed I shall, if I have time. I can't understand why I haven't had
some word before this. There are several possible reasons, of course. If
it wasn't that we know he got to Rue Lafayette I'd say his ship had been
sunk 'without a trace,' as the Germans ordered in other cases. But, of
course, he safely reached this side. Then he just seems to have dropped
out of sight, for I can't believe he was killed when the shell from the
big gun hit the house where he had taken lodging. He may have found it
advisable to return home at once, for some reason, and didn't have a
chance to leave any word for me, or send me any message. And perhaps he
hasn't got back to America yet. Then, too, he may be in Germany, a
prisoner."

"Let us hope not," said Jack, softly, and Tom echoed the wish.

Much as he wished he could devote some time to the search for his
father, Tom realized that he was working under military orders, and,
however dear his father was to him, the sacrifice of his personal
affairs must be made. He knew he would only have time to make some brief
inquiries, and then he and Jack must go with the squadron to the
headquarters assigned to it, as near the location of the big German gun
as possible, and there try to silence it.

The train the picked squadron was traveling on was late, and it was dusk
when they alighted at the railroad station.

"Think we'll have a chance to see anything of the bombardment?" asked
Boughton.

"I was going to say I hoped not," answered Tom, "for I wish the beastly
gun, or guns, would blow up. But that would take away our chance to pot
'em, and I know we all want to do that. You may see something, though
they don't bombard at night as often as they do by day. Of late,
however, before we left, the night firing was more frequent. Possibly
they have found some means of hiding the gun flashes or of letting them
mingle with others along a line so the exact location of the big Bertha
is a matter of doubt."

As they alighted from the train, and were about to seek some taxicabs to
take them to lodgings that had been assigned them, they all became aware
of the fact that something unusual was going on. Suddenly the electric
lights went out, leaving the region about the station, and indeed all of
Paris, in comparative darkness.

At the same time a motor fire engine rushed screeching through the
streets, giving an alarm.

"What is it?" cried Boughton. "Is the big gun firing?"

"It's a Zeppelin raid! I was here once before when they had one," said
the Englishman coolly. "Mind your heads, boys. Just our rotten luck not
to have a machine to go up after it."

He hurried out into the open street where he could have a view of the
sky, and the others followed. There was more excitement than during the
bombardment of the big gun. People were rushing here and there in search
of safe places, and taxicabs, with their lamps like fireflies in the
darkness, were skidding hither and yon, their horns calling for a clear
way.

Suddenly there was a muffled roar, at some distance off. This was
followed by a hoarse murmur, as though a burst of rage from many throats
at the unspeakable outrage of the Huns in killing women and children.

At the same time the anti-aircraft guns, with which Paris is so
efficiently guarded, began to bark and to send their red flashes out
into the blackness of the night. They were shooting at the Zeppelin, as
yet unseen by the men of the picked squadron, and the gunners aimed
according to instructions sent them by wireless from scouts hovering in
the air above the city.

As soon as word comes from the front, about eighty miles from Paris,
that a Zeppelin is on its way to raid, an elaborate system of defense is
put into operation. There are some airmen above Paris all the while,
frequently as many as forty on sentry duty. But when word comes of a
Zeppelin raid the whole squadron, numbering close to three hundred, goes
aloft. By their searchlights, aided by those on the surface, these
fliers endeavor to pick up the German machine, and, too, they endeavor
to get near enough to attack it.

This was what was now going on. Pandemonium appeared let loose, and the
explosion of the German bombs, mingling with the noise of the French
guns, made Paris seem like a battlefield. Occasionally could be heard,
when the guns were silenced for a moment, the roar of the many aeroplane
motors aloft.

The Zeppelin seemed to be over a section of Paris near the Tuileries,
judging by the bursts of light in that direction. Tom, Jack, and their
friends wished with all their hearts that they might take a hand in the
defense, but it was not to be. For perhaps half an hour the
anti-aircraft guns roared out their defiance to the Hun, and then a
large flare of gasolene was lighted in a public square.

This was a signal for the aeroplanes to return, for the Zeppelin had
left, either because she found the situation too perilous for her, or
because she had used up all her bombs.

The lights were turned on again, and the new arrivals watched the
aeroplanes returning one by one, being recognized by their lights in the
air as they moved about like gigantic illuminated insects.

"Well, that's some excitement," observed Tom, as he and the others
finally succeeded in getting cabs, and started for their destination. "I
hope no one was killed."

But the bombs of the inhuman Huns had found several marks, and while the
harm from a military standpoint was small, a number of persons had been
killed. Some damage had been inflicted on the Zeppelin, it was said
later, one brave airman saying he got near enough to spray some bullets
into one of the cabins where a crowd of officers and men were working
the machine.

"We will be with you a little later," said Tom to the other members of
the squadron, as, having reached their lodgings, the two chums set out.

"Where are you going?"

"To call on some ladies," answered Jack, for he and Tom had planned to
see Bessie and her mother.

They reached their own former stopping place, to which they had been
sent by Major de Trouville, but when they inquired for the Gleasons the
landlady, who remembered the boys, stared at them in surprise, and said:

"Why, Madam Gleason and her daughter are not here! They went out this
morning to meet you, and have not come back!"

"To meet us?" gasped Jack.

"Yes, in answer to your note bidding them do so!"




CHAPTER XVII

SEEKING THE GUN


Tom and Jack gazed blankly at one another. The same thought was in the
minds of both.

"The spy!"

"That's who did it," declared Tom. "He forged our names to a note--no
hard task since neither Bessie nor her mother knows our writing very
well--and he's induced them to go some place where he could get them in
his power again."

"But why?" asked Jack.

"Probably because Potzfeldt wanted him to do it. He still has his eye on
Mrs. Gleason's property, I presume, if there is any left after his
robbery."

"It certainly is tough to think that Bessie and her mother have again
fallen into his clutches!" exclaimed Jack. "And we can't do a thing to
rescue them. We've got to report with the others in the morning at the
new aerodrome."

"Yes, but we still have to-night free!" cried Tom. "It will give us
several hours to make a search, and we'll do it! Do you know where Mrs.
Gleason and Bessie went in response to this forged note?" he asked the
landlady.

She mentioned a certain restaurant, not far away, where Tom and his chum
had frequently eaten with Mrs. Gleason and her daughter.

"She was rather surprised to get the note from you," said the landlady,
"and wondered why you didn't come yourself. But she supposed it had
something to do either with your search for your father or with war
matters, so she did not question the messenger. I heard her mention the
place where she and Bessie were going, or I would not know."

"How long ago was it?" asked Jack.

"Oh, just before luncheon time. And they haven't come back."

"The scoundrels have a long start of us!" exclaimed Jack. "We'll have to
do the best we can."

"Better notify the police at once," suggested Tom. "We'll need their
help."

"That's right," agreed his chum.

Their uniform was an open sesame to the police officials, and a
detective was at once detailed to go with the boys to the restaurant.
There, as might have been expected, there was no news. The spy, or
whoever Potzfeldt's agent was, had been too clever for that. All that
could be learned from a taxicab driver was that a lady and a girl,
answering the descriptions of Bessie and her mother, had been met in
front of the restaurant by a man.

The three, after a short talk, had driven off together in an automobile,
and that was the last seen of them.

"But we'll get some trace," declared the detective. "It is hard to get
in or out of Paris now without proper papers. And while, of course, this
spy may have forged documents, there is a chance that we may intercept
him and help your friends. Time is against us, but we will do our best."

Tom and Jack knew that. There was nothing else to do, and so, worried as
they were, they went back to their comrades. Tom made some inquiries
about his father, but, as he feared, no news had come.

As may be imagined Tom and Jack did not pass a very restful night. The
Zeppelin raid had set their nerves on edge, as well as those of every
one else, and it could not be told when the big gun might begin firing
again. Then the fact of Mrs. Gleason and Bessie being missing, and not
knowing in what danger they might be, added to the boys' anxiety.

They paid a late visit to the police, hoping for news, but the spy had
not been apprehended. Then they hurried back to get a little rest
before starting with their comrades of the air to search for the monster
gun.

While these events were transpiring, the French army intelligence
department had not been idle. The officials knew how vitally necessary
it was, in order not to have the morale of the people of Paris weakened,
to do something to find and silence the big guns. And first it was
necessary to discover them.

While this, as yet, had not been done with exactness, owing to the
concealing tactics of the Germans, it was believed that the long-range
cannon was hidden in a certain wood near Laon. French airmen had
endeavored to spy out certain positions there, but an unusually large
number of German planes had fought them off.

"That's pretty good evidence that there must be something doing,"
observed Tom, when he heard this information. "Laon is about ten miles
behind the German lines as they exist at present. Just a breather for a
good French plane. Jack, that's a trip we'll soon be taking."

"I'll be with you, old scout. How's your hand?"

"Oh, all right now. I can hold the joy stick or work the gun. I'm ready
for whatever comes along."

The time had come for the picked squadron to leave Paris and assemble
at the aerodrome assigned to them as their headquarters while the search
for the big gun was in progress. Sad at having to leave without having
some word of Mr. Raymond, and without knowing the fate of Bessie and her
mother, Tom and Jack, nevertheless, bore up well and left with their
comrades, going out of Paris on a train that would eventually bring them
to their headquarters.

In a way their mission was a secret one. Yet it was a question if the
Germans did not guess that something like what really was afoot would be
undertaken in order to silence the super-cannon. They were up to all the
tricks of war, and they must have realized that the French would do as
the Germans themselves would do under similar circumstances.

"Well, this sure is some place!" exclaimed Tom, as they reached the camp
where they were to stay until the gun had been destroyed, or until some
other change in plans was necessary. "It's the best aerodrome we've
struck since we began flying in this war."

"I believe you!" echoed Jack.

The place, though newly established just back of the French lines, where
they opposed the German trenches, was well fitted up for the purpose to
which it was to be devoted.

There were a number of canvas hangars for the aeroplanes, there were
living quarters for the men, a wireless station and a well defended camp
where the aviators might live in comfort during the periods between
their flights.

Of course the place was open to attack by German fliers, but this was
true of every place along the line. Sufficient camouflaging had been
done, however, to render the spot reasonably secure from bombing. Of
course a direct attack from in front would be met by the admirable
French system of defense, and there were plenty of reserves that could
be brought up if a general advance were attempted by the Germans. But as
there was no particular place of any military or strategic importance on
that sector, the worst that was to be feared was an attack from the air.

And this would be guarded against both by the French fliers themselves
and by a battery of the newest type of anti-aircraft gun.

"They don't seem to have forgotten much," observed Tom, as he and Jack,
with the others, went to the quarters assigned to them.

"You said something!" exclaimed Jack, admiringly.

Thus had been set up in this locality, where heretofore no aircraft
activities had been carried on to any extent, a most perfect
escadrille.

It was designed to destroy the big German cannon. Would it succeed?

That was a question every man of the Allies asked.

Shortly after the arrival of the picked squadron at the camp, which, in
honor of Tom and Jack had been named "Lincoln," word came in over the
wireless that the big gun had again fired on Paris.

"It's funny we didn't hear any report of it," said Jack.

"There have been reports enough," Tom remarked. "I've heard the booming
of distant guns ever since we got near this place. Any one of them may
have been the monster, or they may have been firing other guns to hide
the sound of this cannon. Then, too, it may not make as much noise as we
think it ought to. The Germans may have found a new kind of powder, or
even some propelling gas, that makes no extraordinary report. In that
case we couldn't locate the gun by the sound."

"Maybe you're right," agreed Jack. "Anyhow they're firing, that much is
proved; and it's somewhere over there," and he motioned toward the
German lines.

Much as the airmen desired to start at once in their search for the
monster cannon, it was deemed wise to have first a consultation and a
general understanding of what means should be employed.

Then, too, all the aircraft were new, having been shipped to Camp
Lincoln and there assembled, and it was desired to test them before
taking the dangerous flights over the German lines. So the airmen would
have to spend some time--perhaps half a week--in preliminary work.

Meanwhile the great cannon would keep up its deadly, though, from a
military standpoint, useless work.

And so began the preparation, if such it might be called. Every one,
from the most daring "ace" to the humblest kitchen helper in the camp,
was anxious for the day when it could be said that the gun was out of
commission, or guns, if, as was likely, there was more than one. But the
men in command knew the value of thoroughness. There must be no failure
through lack of making proper plans.

But at last everything was in readiness. The planes had been tested,
keyed up, and the motors run until every part of them was humming like a
top. Each man felt confidence, not only in himself but in his craft, and
that meant much. There were several types for the fliers to use,
single-seaters, the big bombing craft, those equipped for slow flying
and from which photographs were to be taken, as well as others. The
taking of photographs was expected to help in revealing the position of
the hidden gun.

The big Italian plane was not ready, it seemed, to be used, but it would
be soon, it was said.

Then came the day and the hour when certain members of the picked
squadron were to take the air to look for the gun. Tom and Jack, to
their delight, were selected to go.

"What a chance!" exclaimed Jack, as he climbed into his machine, and saw
that he had plenty of ammunition for the Lewis gun.

"I hope we can make good!" returned Tom.

Then they were away and up, seeking to find the monster cannon that was
bringing the war into the heart of Paris.




CHAPTER XVIII

A CLOUD BATTLE


For some little time the picked squadron that was intrusted with the
difficult and dangerous task of locating the big German gun flew over
the French lines. Below them Tom and Jack could make out various French
camps, the front and supporting lines of trenches, and various other
military works. They could see a brisk artillery duel going on at one
point. They noted the puffs of smoke, but of course could not hear the
explosions, as their own motors were making too much noise.

Tom and Jack kept within sight of one another, and also within view of
their comrades. Each plane was marked with a big number so it could be
distinguished, for the aviators themselves were so wrapped in
fleece-lined clothes, so attired in gauntlets, goggles and fur boots, as
protection against the terrible cold of the upper regions, that one's
closest friend would not recognize him at a near view.

It was the object of this first scouting expedition to make a
preliminary observation over as wide a range of the enemy's country as
possible. While it was hoped that the location of the big gun might be
spied out, it was almost too much to expect to pick out the spot at the
first trial. The Germans were keen and wary, and undoubtedly they would
have laid their plans well.

"Well, I don't see any of 'em coming out to dispute our passage,"
thought Tom, as he looked at his controls and noted by his height gage
that he was now up about two miles. "There isn't a Boche plane in
sight."

And the same thing was observed by Jack and the other fliers. The
Germans seemed to be keeping down, or else were higher up, or perhaps
hidden by some cloud bank.

That was another hazard of the air. Going into a cloud, or above it
might mean, on coming out, that one would find himself in the midst of
enemies.

It is a life full of dangers and surprises. It is this which makes it so
appealing to the young and brave.

On and on flew the Allied planes, and the eager eyes of the pilots were
alternately directed toward the earth and then ahead of them, and upward
to discern the first sight of a Hun machine, if such should venture out.

The fliers were now well over the German lines, and the batteries from
below began firing at them. This was to be expected, and Tom, Jack and
the others had gotten used to the bursts of shrapnel all around them.
They could see the puffs of smoke where the shells burst, but they could
hear no sounds.

"The 'Archies' are busy this morning," thought Jack, as he noted the
firing from below, and using the French slang word for the German
anti-aircraft guns.

He took a quick glance toward Tom's machine to make sure his chum, so
far, was all right. Assured on this point Jack looked to his own craft.

"Well," he mused, "at this point the 'flaming onions' can't get us, but
they may pot us as we go down, as we'll have to if we want to get a good
view of the ground where the big gun may be hidden."

The "flaming onions," referred to by Jack, were rockets shot from a
ground mortar. They have a range of about a mile, and when a series of
them are shot upward in the direction of a hostile plane it is no easy
matter for the aviator to pass through this "barrage." Once a "flaming
onion" touches an aeroplane the craft is set on fire, and then, unless a
miracle happens, the aviator falls to his death.

The German gunners, however, could not use these to advantage while the
French planes kept so high up, though the shrapnel was a menace, for
the Hun guns shot far and with excellent aim. A number of the scout
machines were hit, Tom's receiving three bullets through the wings,
while Jack's engine was nicked once or twice, though with no serious
damage.

But as for the German planes they declined the combat that was offered
them. Probably they had different plans in view. It soon became evident
to Tom, Jack and the others that to fly at that height meant discovering
nothing down below. The distance was too great. The big gun might be
hidden almost anywhere below them, but until it was fired, disclosing
its presence by an unusual volume of smoke, it would not be discovered.
Also its fire might be camouflaged by a salvo from a protecting battery.

"It's about time he did that," said Tom to himself at last, as he
noticed Cerfe, who was the leader of the air squadron, dip his plane in
a certain way, which was the signal for going down. "We've got to get
lower if we want to see anything," the young aviator went on. "Though
they may pot some of us."

Down they went, flying comparatively low but at great speed in order to
offer less of a target to the gunners below them. And, following
instructions, each pilot noted carefully the section of the German
trenches beneath him, and the area back of them. They were seeking the
big gun.

But, though they looked carefully, it could not be seen, and finally
when one of the French machines was badly hit, and the pilot wounded, so
that he had to turn back toward his own lines, Cerfe gave the signal for
the return.

In all this time not a Hun plane had come out to give battle. What the
reason for this was could only be guessed at. It may have been that none
of the German machines was available, or that skillful pilots, capable
of sustaining a fight with the veterans of the French, were not on hand
just then. However that may have been, Tom, Jack and the others, after
firing a few rounds from their machine guns at the trenches, though
without hope of doing much damage, turned back toward Camp Lincoln.

"Well, then you did not discover anything?" asked Major de Trouville,
who had been transferred and given the command at Camp Lincoln.

"Nothing," answered Jack.

"If it's in the section we covered, it is well hidden," added Tom.

"And I think, don't you know," went on the Englishman, Haught, "that the
only way we'll be able to hit on the bally mortar is to fly low and take
photographs."

"That's my idea," said the major. "If we take a series of photographs
we can develop them, enlarge them, if necessary, and examine them at our
leisure. I had thought of this, but it's a slow plan, and it
means--casualties. But I suppose that can't be avoided. But I wanted to
try the scouting machines first.

"After all, the taking of photographs from the air of the enemy trenches
and the land behind them is a most valuable method of getting
information," he continued.

Men, specially trained for such observation work, examine the
photographs after the aviators return with the films, and they can tell,
by signs that an ordinary person would pass over, whether there is a new
battery camouflaged in the vicinity, whether preparations are under way
for receiving a large number of troops, or whether a general advance is
contemplated. Then measures to oppose this can be started. So, Major de
Trouville was right, photography forms a valuable part of the new
warfare.

The photographing of the enemy positions is done in big, heavy machines,
carrying two men. They must fly comparatively low, and have not much
speed, though they are armed, and it takes considerable of an attack to
bring them down. But of course the pilot and his observer are in danger,
and, to protect them as much as possible, scout planes--the single-seat
Nieuports--are sent out in squadrons to hover about and give battle to
the German aircraft that come out to drive off the photographers.

"We'll undertake that," proceeded Major de Trouville. "I'll order the
big machine to get ready for an attempt to-morrow at locating the gun."

"Is it still shooting?" asked Jack.

"Yes, it has just been bombarding Paris; but I have no reports yet as to
the damage done."

"Aren't we doing anything at all?" asked Tom.

"Oh, yes, our batteries are keeping up a fire on the German lines along
the front behind which we think the gun is concealed, but what the
results are yet, we don't know."

"Well, let's hope for clear weather to-morrow," suggested Boughton.

The intervening time was occupied by the aviators in getting everything
in readiness. The machines were inspected, the automatic guns gone over,
and nothing left undone that could be thought of to give success.

The next day dawned clear and bright, and, as soon as it was light
enough to make successful photographs, the big machine set out, while
hovering above and to either side of it were several Nieuports. Tom and
Jack were each occupying one of these, ready to give battle to the Huns
above or below the clouds.

In order to distract the attention of the Germans as much as possible
from the direct front where the airships were to cross the lines, a
violent artillery fire was maintained on either flank. To this the
Germans replied, perhaps thinking an engagement was pending. And so,
amid the roar of big guns, the flying squadron got off.

"Now we'll see what luck we'll have," mused Tom, as he drove his machine
forward, being one of the large aerial "V" that had for its angle the
ponderous photographing bi-motored machine.

Over the German lines they flew, and then the Germans awoke to the
necessity of ignoring the fire on their flanks and began shooting at the
airships over their heads.

"This ought to bring out their pilots if they have any sporting blood,"
thought Jack.

And it did. The French and their allies were no more than well over
German-occupied territory, before a whole German air fleet swarmed up
and advanced to give battle. They flew high, intending to get above
their enemies, and so in the most favorable fighting position. But Tom,
Jack and the others saw this, and also began to elevate their planes.

"We certainly are going up!" mused Tom, as he noted the needle of his
height gage showing an altitude of twelve thousand feet. "When are they
going to stop? We're high above the clouds now."

That was true as regarded himself, Jack, and two other French planes.
But still the Germans climbed. Doubtless some of them were engaging the
big machine which was low down, trying to take photographs, but Cerfe
and Boughton were guarding that.

"Here comes one at me, anyhow!" thought Tom, as he saw a Hun machine
headed for him.

"Well, the sooner it's over the better. Here goes!" and he pressed the
release of his automatic gun, meanwhile heading his craft full at the
German to direct the fire, for that is how the guns are aimed in a
Nieuport, the gun being stationary.

And so began the battle above the clouds.




CHAPTER XIX

QUEER LIGHTS


Tom Raymond's first few shots went wild, as he noted by the tracer
bullets. Then, steering his machine with his feet, he brought it around
a trifle, and, having by a quick action risen above his antagonist, he
let him have a good round, full in the face. The result was disastrous
to the German, for suddenly the Hun machine burst into flames, the
gasolene from the punctured tank burning fiercely, and down it went a
flaming torch of death.

Tom felt some bullets whistle around him, and one exploded as it struck
part of his engine, but without injuring it.

"Explosive bullets, are they?" mused the young aviator. "Against all the
rules of civilized warfare. Well, he won't shoot any more," he thought
grimly.

But though Tom had come victorious from his engagement with his single
antagonist, he had no sooner straightened out and begun to take stock of
the situation, than he became aware that he was in great danger. Above
him, and coming at him with the swiftness of the wind, were two speedy
German machines, bent cm his destruction.

They were both firing at him, the angles of attack converging, so that
if one missed him the other would probably get him.

"I've got to get out of this," Tom reasoned. He headed his plane toward
the antagonist on his right, shooting upward and firing as rapidly as he
could, and had the satisfaction of seeing the German swerve to one side.
The fire was too hot for his liking.

The other, however, came on and sent such a burst of fire at Tom that
the latter realized it was a desperate chance he was taking. He tried to
get above his enemy, but the other's plane was the speedier of the two,
and he held the advantage.

Tom's ammunition was running low, and he realized that he must do
something. He decided to take a leaf out of the book of the Germans.

"I'll go down in a spinning nose dive," he reasoned. "They'll be less
likely to hit me then. I'll have to go back, I guess, and get some more
shots. I used more than I thought."

He sent his last drum at the persistent German, and, noting that the
other was swooping around to attack again, went into the dangerous
spinning nose dive.

The Germans may have thought they had disabled their antagonist, for
this dive is one a machine often takes when the pilot has lost control.
But in this case Tom still retained it, and when he had dropped out of
the danger zone, he prepared to straighten out and fly back over his own
lines.

It is not easy to straighten an airplane after such a dive, and for a
moment Tom was not sure that he could do it. Often the strain of this
nose dive, when the machine is speeding earthward, impelled not only by
its propellers, but by the attraction, of gravitation, is so great as to
tear off the wings or to crumple them. But after one sickening moment,
when the craft seemed indisposed to obey him, Tom felt it beginning to
right itself, and then he started to sail toward the French lines.

He was not out of danger yet, though he was far enough away from the two
German machines. But he was so low that he was within range of the
German anti-aircraft guns, and straightway they began shooting at him.

To add to his troubles his engine began missing, and he realized that it
had sustained some damage that might make it stop any moment. And he
still had several miles to travel!

But he opened up full, and though the missing became more frequent he
managed to keep the motor going until he was in a position to volplane
down inside his own lines, where he was received with cheers by his
comrades of the camp.

"How goes it?" asked Major de Trouville anxiously.

"I think we are holding them off," said Tom.

He was the first one who had had to return, much to his chagrin. He
leaped out of his craft, and was about to ask for another to go back and
renew the battle of the clouds, when he saw the big photographing
machine returning, accompanied by all but two of the escorting craft.

"A pair missing," murmured the major, as he searched the sky with his
glasses.

And Tom wondered if Jack's machine was among those that had not headed
back.

Eagerly he procured a pair of binoculars, and when he had them focused
he identified one machine after another, at last picking out his chum's.
It did not seem to be damaged.

But two of the French craft had been brought down--one in flames, the
report had it, and the other out of control, and both fell within the
German lines.

"Did you get any photographs of the big gun?" asked the major, when the
men in the double machine had made a landing.

"We got lots of views," answered the photographer, "but what they show
we can't say. As far as having seen the gun goes, we didn't spot it."

"Well, maybe the photographs will reveal it," suggested the major. "Ah,
but I am sorry for the two that are lost!"

Jack's experience had been less exciting than Tom's. One machine had
attacked the former, and there had been a hot engagement for a while,
but the German had finally withdrawn, though to what extent he was
wounded or his machine damaged Jack did not know.

However, the picked squadron had reason to feel satisfied with their
efforts. All now depended on the developing of the photographs, and this
was quickly done. For this part of warfare is now regarded as so
important that it is possible for a plane to fly over an enemy's
station, take photographs and have prints in the hands of the commanding
officer inside of an hour, if all goes well.

Carefully the photographs were examined by men expert in such matters.
Eagerly they looked to discover some signs of the emplacement of the big
gun. But one after another of the experts shook his head.

"Nothing there," was the verdict.

"Then we've got to try again," decided Major de Trouville. "We must
find that gun and destroy it!"

"Well, we're ready," announced Tom, and the others of the picked
squadron nodded in assent.

And then began an organized campaign to locate the monster cannon. It
continued to fire on Paris at intervals. Then three days went by without
any shells falling, and the rumor became current that the gun had burst.
If this had happened, there was another, or more, to take its place, for
again the bombarding of the city began.

Meanwhile the air scouts did their best to find the place of the firing.
Hundreds of photographs were taken, and brave scouts risked death more
than once in flying low over suspected territory. But all to no purpose.
Several were killed, but others took their places. Jack was hit and so
badly wounded that he was two weeks in the hospital. But when he came
out he was again ready to join Tom in the search.

No word came as to the whereabouts of Bessie and her mother, nor did Tom
hear anything of his father. The lack of information was getting on the
nerves of both boys, but they dared not stop to think about that, for
the army needed their best efforts as scouts of the air, and they gave
such service gladly and freely.

Every possible device was tried to find the location of the German gun,
and numerous battles above the clouds resulted at different times during
the scout work.

On the whole the advantage in these conflicts lay with the armies of the
Allies, the Germans being punished severely. Once a German plane was
brought down within the French lines, and its pilot made a prisoner.

It was hoped that some information might be gotten out of the German
airman that would lead to the discovery of the big gun, but, naturally,
he did not reveal the secret; and no more pressure was brought to bear
on him in this matter than was legitimate. The hiding place of the gun
remained a secret.

Its possible size and the nature of its shooting was discussed every day
by Tom, Jack and their comrades. In order to make a cannon shoot a
distance of about eighty miles it was known that it was necessary to get
the maximum elevation of forty-five degrees. It was also calculated that
the shell must describe a trajectory the highest point in the curve of
which must be thirty-five miles or more above the earth. In other words
the German cannon had to shoot in a curve thirty-five miles upward to
have the missile fly to Paris. Of course at that height there was very
little air resistance, which probably accounted for the ability of the
missile to go so far. That, and the sub-calibre shell, made the
seemingly impossible come within the range of possibility.

"What are you going to do, Tom?" asked Jack one evening, after an
unsuccessful day's flight. For Tom was going toward his hangar.

"Going up."

"What for?" Jack went on.

"Oh, no reason in particular. I just feel like flying. We didn't do much
to-day. Had to come back on account of mist, and we didn't see enough to
pay for the petrol used. Want to come along?"

"Oh, I might, yes."

Tom and Jack went up, as did several more. But the two remained up
longer than did the others, and Jack was somewhat surprised to see his
chum suddenly head for the German lines, but at an angle that would take
him over them well to the south of where the observation work had been
carried on.

"I wonder what he's up to," mused Jack; "Guess I'd better follow and
see."

There was not much chance of an aerial battle at that hour, for dusk was
coming on. There had been no bombing squadron sent out, which would
have accounted for Tom going to meet them, and Jack wondered greatly at
his chum's action.

Still there was no way of asking questions just then, and Jack followed
his friend. They sailed over the German lines at a good height, and Jack
could keep Tom in view by noting the lights on his plane.

These were also seen by the Germans below, and the anti-aircraft guns
began their concert, but without noticeable effect. None of the Hun
airmen seemed disposed to accept a challenge to fight, so Tom and Jack
had the upper air to themselves.

Below them the boys could see flashes of fire as the various guns were
discharged; and at one point in the lines there was quite an artillery
duel, the French batteries sending over a shower of high explosive
shells in answer to the challenge from the Boches.

It was not until Jack had followed his chum back to Camp Lincoln, and
they had made a landing, that a conversation ensued which was destined
to have momentous effect.

"Jack, did you notice the peculiar colored lights away to the north of
where we were flying?" asked Tom, as they divested themselves of their
fur garments.

"You mean the orange colored flare, that turned to green and then to
purple?" asked Jack.

"That's it. I thought you'd see it. I wonder what it means?"

"Oh, perhaps some signal for a barrage or an attack. Or they may have
been signaling another battery to try to pot us."

"No, I hardly think so. They didn't look like signal fires. I must ask
Major de Trouville about that."

"What?" inquired the major himself, who was passing and who heard what
Tom said.

"Why, we noticed some peculiar lights as we were flying over the German
lines in the dark. There was an orange flare, followed by a green light
that changed to purple," answered Tom.

"There was!" cried the major, seemingly much excited. "You don't mean
it! That's just what we've been hoping to see! Come, you must tell
Laigney about this."




CHAPTER XX

THE BIG GUN


For a moment Tom and Jack did not quite know what to make of the
excitement of Major de Trouville. And excited he certainly was beyond a
doubt.

"You must come and tell this to Lieutenant Laigney at once," he said.
"It may mean something important. Are you sure of the sequence of the
colors?" he asked. "That makes all the difference."

"There was first an orange tint," said Tom, "which was followed by green
and purple, the last gradually dying out."

"Orange, green and purple," murmured the major. "Can it be that for
which we are seeking?"

He hurried along with the boys, seemingly forgetting, in his haste and
excitement, that he was their ranking officer. But, as has been noted,
the aviators are more like friends and equals than officers and men.
There is discipline, of course, but there is none of the rigidity seen
in other branches of the army. In fact the very nature of the work
makes for comradeship.

Tom and Jack knew, slightly, the officer to whom Major de Trouville
referred. Lieutenant Laigney was an ordnance expert, and the inventor of
a certain explosive just beginning to be used in the French shells. It
was simple, but very powerful.

"You must tell him what you observed--the strange colored lights, my
boys," said the major. "By the way, I hope you carefully noted the time
of the colored flares."

Tom and Jack had. That was part of their training, to keep a note of
extraordinary happenings and the time. Often seemingly slight matters
have an important bearing on the future.

They found Lieutenant Laigney in his quarters, making what seemed to be
some intricate calculations. He saluted the major and nodded to the
boys, whom he had met before.

"Lieutenant," began Major de Trouville, "these young gentlemen have
something to tell you. I want you to think it over in the light of what
you told me about the action of that new explosive you said the Germans
might possibly be using."

"Very good, Major. I shall be delighted to be of any service in my
power," was the answer.

Then Tom and Jack described what they had seen, giving the location of
the colored lights as nearly as they could, and the exact time they had
noted them.

"How long would it take a shell to reach Paris, fired at a distance of
eighty miles from the city?" asked the major.

The lieutenant made some calculations, and announced the result of his
findings.

"Then," went on the commanding officer, "if a shell was fired from the
big gun, say at the moment when these two scouts observed the
tri-colored fire, it should have reached Paris at seven-fifty-three
o'clock."

"As nearly as can be calculated, not knowing the exact speed of the
projectile, yes," answered the lieutenant.

Major de Trouville picked up the telephone and asked to be connected
with the wireless station.

"Have you had any reports of the bombarding of Paris this evening?" he
asked. "Yes? What time did the first, or any particular shell, arrive?
Ah, yes, thank you. That is all at present."

He turned to the others, after having listened to the reply and put the
instrument away.

"One of the shells exploded in a Paris street at seven-fifty-two o'clock
this evening," he said.

"It beat your calculations by one minute, Lieutenant Laigney."

"Ah! Then this means--" and the younger officer seemed as excited as the
major had been when Tom and Jack told him what they had seen.

"It means," finished the commanding officer, "that, in all likelihood,
these young men have discovered the location of the big German cannon."

"Discovered it!" cried Jack. "Why we didn't see anything!"

"Nothing but those queer lights," added Tom.

Major de Trouville smiled at them, and Lieutenant Laigney nodded his
head in assent.

"Those queer lights, as you call them," said the ordnance expert, "were
the flashes of a new explosive. What the Germans call it I do not know.
For want of a better name we call it Barlite, from the name of Professor
Barcello, one of our experimenters, who discovered it. But a spy stole
the secret and gave it to Germany. They must have managed to perfect it,
though we have not used it as yet, owing to the difficulty in
constructing a gun strong enough to withstand its terrific power."

"And do you mean they're using this explosive in the big German gun?"
asked Jack, "And that we really saw it being fired?" cried Tom.

"That is my belief," said the lieutenant. "This explosive burns, when
fired from a gun, first with an orange flame, changing to green and then
to purple, as the various gases are given off."

"Those are the very colors we saw!" exclaimed Jack.

"Yes," went on Major de Trouville. "And when I heard you mention them,
and when I recalled that Lieutenant Laigney had spoken of a certain
explosive that gave off a tri-colored light, I suspected you had hit on
the German secret."

"And do you believe we actually saw the giant cannon being fired at
Paris?" asked Tom.

"Without a doubt. The time of the arrival of one of the shells coincides
almost to the minute with the time that would elapse after the missile
was sent on its way, and this was when you saw the queer flashes. You
have discovered the area where the big gun is placed. All that is needed
now are some exact observations to give us the exact spot."

"And then we can destroy it!" cried the lieutenant. "Then the menace to
beloved Paris will have passed!"

"And thanks to our brave American friends!" cried the major, shaking
hands with Tom and Jack. "You will win promotion for this!" he murmured.

"But the big gun isn't found yet," said Jack.

"Why, if you are right, sir," Tom said to the major, "the shells must
pass right over our camp."

"They probably do. But at so far above--several miles up so as to reach
the height of thirty-five--that we never know it. We neither see them
nor hear them. Boys, I believe you have located the big gun! All that
now remains is to destroy it!"




CHAPTER XXI

DEVASTATING FIRE


Modestly enough Tom and Jack took the new honors that came to them. As a
matter of fact they were in no wise sure that they had discovered the
location of the German giant cannon. It was all well enough to come in
and report seeing some strange-colored flares of fire. But Tom and Jack
felt that they wanted to see a thing with their own eyes before surely
believing.

Of course, though, the French experts knew about what they were talking,
and the major and the lieutenant seemed very sure of their ground.

"I only hope we have had the good luck to have spotted the beasts'
machine," said Tom.

"You will have the honor of proving it to yourselves in the morning,"
Major de Trouville told them. "You shall accompany the first scouting
party that goes out. We will send out two photographing machines, and
enough of a squadron to meet anything the Huns can put forth. Paris
shall be delivered from the Boche pests!"

"We'll do our best," said Tom, and Jack nodded in agreement.

It did not take long for the news to spread about Camp Lincoln that the
two young United States aviators had, very probably, discovered by
accident the big German gun.

And in telling what they had seen Tom and Jack remarked that the
peculiar tri-colored fire had been in the midst of other flashes of
flame, and, doubtless, smoke, but that could not be seen on account of
the darkness.

"The other flashes were probably guns fired to camouflage the flash from
the giant cannon, or possibly cannons," observed Major de Trouville.
"But we shall see what to-morrow brings forth."

The hours of the night seemed long, but there was much to do to get
ready for the next day's operations. More aviators were sent for, and
the men of the air spent many hours tuning up their motors and seeing to
their guns, while the big machines, which it was hoped could take
pictures of the giant cannon's position, were gone over carefully.

In addition some powerful French guns were brought up--some of the
longest range guns available, and it was hoped that the big aeroplanes
might signal by wireless the exact location of the super-gun, so that a
devastating fire could be poured on it, as well as bombs be dropped
from some machines especially fitted for that work.

Camp Lincoln, where the picked squadron was situated, was in the
neighborhood of Soissons, France, in a sector held by the French troops.
The lines of German and French trenches, with No Man's Land in between,
was about ten miles to the east of this point. This section had changed
hands twice, once being occupied by the Germans, and then abandoned by
them when they made the great withdrawal.

Now, perhaps ten miles back of the German trenches, the great gun was
hidden, making its total distance from Paris about eighty miles, but its
distance from Camp Lincoln something less than twenty miles.

Modern guns easily shoot that distance, but the commander of the forces
in this section was going to shorten that. Soissons was the nearest
large city to the camp. As a matter of fact the air squadron was some
distance east of that place, and nearer the battleline. So that it was
comparatively easy, once the location of the big gun was known, to bring
up heavy artillery behind the French lines to batter away at its
emplacement.

After a night of arduous labor, during which there was anxiety lest the
Germans find out what was going on, morning broke, and to the relief of
all it was bright.

There was an early breakfast, and then the aviators' helpers wheeled the
machines from the hangars. Several big photographing craft were in
readiness, and ten bombing planes were in reserve.

Major de Trouville inspected his brave men. They were as eager as dogs
on the leash to be off and at the throat of the Huns. A wireless message
from Paris had come in soon after breakfast, stating that nearly a score
had been killed in the capital the previous night by fire from the
"Bertha."

"And it's up to us to avenge them!" exclaimed Jack.

"That is what we'll do if we have any luck!" added Tom grimly.

There was a last consultation of the officers, instructions were gone
over, and everything possible done to insure success. The moment a big
gun was sighted, the signal was to be given and the French long-range
cannon would open fire, while the bombing machines would also do their
part.

"All ready! Go!" called the major, and there was a rattle and a roar
that drowned his last word. The men of the air were off.

Led by Tom and Jack, the others followed. Up and up they arose, the
smaller planes flying high as a protection to the more cumbersome
machines of the bi-motored type. And soon the squadron, the largest that
had yet ascended from Camp Lincoln, was hovering over the German lines.

The Huns seemed to realize that something more than an ordinary attack
from the air was impending, for soon after the anti-aircraft guns began
firing a swarm of German aviators took the air, and there was no
shirking battle this time. The Huns so evidently felt the desperate need
of driving away their attackers, that this, more than what the major and
lieutenant had said, convinced Tom and Jack that they were at last on
the track of the big gun.

Of course the two boys could not communicate with one another, but they
said afterward that their thoughts were the same.

The battle of the air opened with a rush and a roar. The Germans, though
outnumbered by their opponents, did not hesitate, but came on fiercely.
They attacked first the big photographing planes, for they realized that
these were the real "eyes" of the squadron. The impressions they
received, and the views they carried back, might mean the failure of the
German plans.

But the French were ready for this, and the swift little Nieuports,
dashing here and there, swooping and rising, attacked the other planes
vigorously.

It was give and take, hammer and tongs, fire and be fired on, smash and
be smashed. It was not as one-sided a battle as it would seem it might
have been owing to the superiority of numbers in favor of the French--at
least at first. Several of the Allies' planes were sent down, either out
of control, or in flames. But the Huns paid dearly for their quarry.

Jack and Tom ran serious risks, for the Germans, realizing that the two
leading planes had some special mission, attacked them fiercely. Tom
managed to shake off and disable his antagonist. But Jack's man shot
with such good aim that he pierced his gasolene tank, and had it not
been that Jack was able to thrust into the hole one of some wooden plugs
he had brought along for the purpose, he might have had to come down
within the German lines. But the wood swelled, filled the hole, and then
the petrol came out so slowly that there was comparatively little
danger.

And having, with some of their companions, fought their way through the
German air patrol, and having escaped with minor damage to their guns,
Jack and Tom looked down at the place where they had seen the queer
lights.

And then, high up and at a vantage point, while below them hovered their
photographing planes, the two young aviators beheld a curious sight.

In German-occupied territory, but on French soil, they saw near a
railroad junction, where they were fairly well hidden in a camouflaged
position, not one, but three monster Hun cannons. The guns looked more
like gigantic cranes than like the accepted form of a great rifled piece
of armament. The guns were so mounted that they could be run out on a
small track at the moment of firing, and then propelled back again, like
some of the disappearing cannon at Sandy Hook and other United States
forts. Only the German guns advanced and retreated horizontally, while
the usual method is vertically.

"We've discovered 'em! There they are!" cried Tom, but of course he
could not hear his own voice above the roar of his motor. But he knew
that he and Jack were over the very spot where the night before they had
seen the colored flares from the great guns.

And they had, indeed, by a most lucky chance, located the big German
guns, for there were three of them. They were placed almost midway
between the railroad station of Crepyen-Lannois and the two forts known
as "Joy Hills," forts which had fallen into German hands. There were
two railroad spur lines from the station, and on these the heavy guns
were moved to position to fire, and then run back again. Other spur
lines were under course of construction, Jack and Tom, as well as the
other airmen, could observe, indicating that other guns were to be
mounted, perhaps to take the place of some that might be destroyed.

As a matter of fact, as was learned later, there were but two guns in
service at this time, one of the three having burst.[1]

[Footnote 1: While of course this story is fiction, the description
given above of the great guns and their method of firing and concealment
is strictly in accord with the facts, and made from a sight of aeroplane
photographs taken by the French, and from an official report, published
April 26, 1918, by Deputy Charles Leboucq of the Department of the
Seine.]

Even as the French squadron came hovering over the place where the
German monster guns were placed, the advance of Tom, Jack and their
comrades being disputed by the Huns, one of the super-guns was run out
to fire on its specially constructed platform.

That this should be done in the very faces of the French was probably
accounted for by the fact that the Germans were taken by surprise. It
took some little time to arrange for firing one of the big cannons, and
it was probably too late, after the French airmen were hovering above
it, to get word to the crew not to discharge it.

As it happened, Tom and Jack, with Boughton, who had kept pace with
them, witnessed the firing of the big gun. As it was discharged, ten
other heavy guns, but, of course, of much less range, were fired off,
being discharged as one to cover the report of the giant mortar. And at
the same time dense clouds of smoke were sent up from surrounding hills,
in an endeavor to screen the big gun from aeroplane observation. But it
was too late.

In another moment, and even as the echoes of the reports of the ten
cannons and the big gun were rumbling, the bombing machine of the French
came up and began to drop explosives on the spot. At the same time word
of the location of the great cannon was wirelessed back to the camp, and
there began a devastating fire on the guns that had been, and were even
then, bombarding Paris.




CHAPTER XXII

OVER THE RHINE


It was a battle of the air and on the ground at the same time. From
above the French, American and British airmen were dropping tons of
explosives on the emplacements of the big guns and on the railway spurs
that brought them to the firing points. It might seem an easy matter for
an airship flying over a place to drop an explosive bomb on it and
destroy it. But, on the contrary, it is very difficult.

The bombing plane must be constantly on the move, and it takes a pretty
good eye to calculate the distance from a great height sufficiently well
to make a direct hit.

But a certain percentage of the bombs find their mark, and they did in
this case. Tom and Jack, as well as the other scouts, looking down from
their planes, saw fountains of brown earth being tossed into the air as
the French bombs exploded. At the same time the photographers in the
other planes were making pictures of the guns and their location.

They were hindered in this not only by the shooting of the Germans from
below, who were working their anti-aircraft guns to their capacity, but
by screens of smoke clouds, which were emitted by a special apparatus to
hide the big guns. At the same time other cannons were being fired to
disguise the sound from the immense long-range weapon, but this was of
little effect, now that the location had been discovered.

Meanwhile a score or more of the Hun planes appeared in the air. They
had taken flight as soon as their pilots saw the squadron of enemy
machines approaching, and were eager, this time, to give battle.

"Our work's being cut out for us," murmured Tom, as he steered his
machine to engage a German who seemed eager for the fray. Tom sent a
spray of bullets at his enemy, and was fired at in turn. He knew his
craft had been hit several times, but he did not think it was seriously
damaged.

Jack, too, as he could tell by a quick glance, was also engaged with a
German, but Tom had no time then to bestow on mere observation. His
antagonist was a desperate Hun, bent on the utter destruction of Tom's
machine. They came to closer quarters.

Down below the fighting was growing more furious. It was in the form of
an artillery duel. For now the French observation machines were
wirelessing back the range, and French shells were falling very near the
big guns.

The heavy guns, in modern warfare, are placed miles away from the
objects they wish to hit, and the only way to know where the targets are
is by aeroplane observation. When the guns are ready to fire one of the
artillery control planes goes up over the enemy's territory. Of course
it is the object of the enemy to drive it away if possible.

But, hovering in the air, the observer in the double-motored machine
notes the effect of the first shot from his side's cannon. If it goes
beyond the mark he so signals by wireless. If it falls short he sends
another signal. Thus the range is corrected, and finally he sees that
the big shells are landing just where they are needed to destroy a
battery, or whatever is the object aimed at. The observation complete,
the machine goes back over its own lines--if the Germans let it.

This sort of work was going on below them while Tom, Jack and the others
in the Nieuports were engaging in mortal combat with the Hun fliers.
Some of the heavy French shells fell beyond the emplacements of the big
guns, and others were short. The observers quickly made corrections by
wireless for the gunners. Tom Raymond, after a desperate swoop at his
antagonist, sent him down in flames, and then, seeking another to
engage, at the same time wondering how Jack had fared, the young aviator
looked down and saw one of the largest of the French shells fall
directly at the side of the foremost of the three German giant cannons.

There was a terrific explosion. Of course, Tom could not hear it because
of his height and the noise his motor was making, but he could see what
happened. A great breach was made in the long barrel of the German gun,
and its emplacement was wrecked, while the men who had been swarming
about the place like ants seemed to melt into the earth. They were
blotted out.

"One gone!" exclaimed Tom grimly. And then he noted that the other two
guns had been withdrawn beneath the camouflage. They were no longer in
sight, and hitting them was a question of chance.

Still the French batteries kept up their fire, hoping to make another
hit, but it would be a matter of mere luck now, for the guns were out of
observation.

The airmen observers, however, still had a general idea of where the
super-weapons were, and the French gunners continued to send over a rain
of shells, while the bombing machines, save one that had been destroyed
by the German fire, kept dropping high explosives in the neighborhood.

"The place will be badly chewed up, at any rate," mused Tom.

He glanced in the direction where he had last seen Jack, and to his
horror saw his chum's machine start downward in a spinning nose dive.

"I wonder if they've got him, or if he's doing that to fool 'em,"
thought Tom. As he was temporarily free from attack at that instant he
started toward his friend. Hovering over him, and spraying bullets at
Jack, was a German machine, and Tom realized that this fighter might
have injured, or even killed, Jack.

"Well, I'll settle your hash, anyhow!" grimly muttered the young birdman
to himself. He sailed straight for the Hun, who had not yet seen him,
and then Tom opened fire. It was too late for the German to turn to
engage his second antagonist, and Tom saw the look of hopelessness on
his face as the bullets crashed into his machine, sending it down a
wreck.

"So much for poor old Jack!" cried Tom.

They were well over the German lines now, and the fight was going
against the French. That is, they were being outnumbered by the Hun
planes, which were numerous in the air. But the French had accomplished
their desperate mission. One of the German guns was out of commission,
and perhaps others, while the location had been made "considerably
unhealthy," as Boughton expressed it afterward.

It was time for the French to retire, and those of their machines that
were able prepared to do this. But Tom was going to see first what
happened to Jack before he returned to his lines.

"He may be spinning down, intending to get out of a bad scrape that way,
and then straighten for a flight toward home," mused Tom. "Or he may
be--"

But he did not finish the sentence.

There was but one way for Tom to be near Jack when the latter landed--if
such was to be his fate--and to give him help, provided he was alive.
And that was for Tom himself to go down in a spinning nose dive, which
is the speediest method by which a plane can descend. But there is great
danger that the terrific speed may tear the wings from the machine.

"I'm going to risk it, though," decided Tom.

Down and down he spun, and as he looked; he became aware, to his joy,
that Jack had his machine under some control.

"He isn't dead yet, by any means," thought Tom. "But he may be hurt. I
wonder if he can make a good landing? If he does it will be inside the
German lines, though, and then--"

But Tom never faltered. He must rescue his chum, or attempt to, at all
hazards.

Down went both machines, Jack's in the lead, and then, to his joy, Tom
saw his friend bring the machine on a level keel again and prepare to
make a landing. This was in a rather lonely spot, but already, in the
distance, as Tom could note from his elevated position, Germans were
hurrying toward the place, ready to capture the French machine.

"If he's alive I'll save him!" declared Tom. "My machine will carry
double in a pinch, but he'll have to ride on the engine hood."

Tom was going to take a desperate chance, but one that has been
duplicated and equalled more than once in the present war. He was going
to descend as near Jack's wrecked machine as he could, pick up his chum,
and trust to luck to getting off again before the Germans could arrive.

That Jack was once more master of his craft became evident to his
friend. For the Nieuport was slowing down and Jack was making ready for
as good a landing as possible under the circumstances. It was plain,
however, that his machine was damaged in some way, or he would have gone
on flying toward his own lines.

Tom saw his chum drop to the ground, and then saw him quickly climb out
of his seat, loosing the strap that held him in. By this time other
German planes were swooping toward the place, and a squad of cavalry was
also galloping toward it.

"I'll beat you, though!" cried Tom fiercely.

He throttled down his engine, intending to give it just enough gas to
keep it going, for he would have no one to start it for him if the motor
stalled. He calculated that he could taxi the craft across the ground
slowly enough for Jack to jump on and then he could get away, saving
both of them.

Jack understood the plan at once. He waved his hand to Tom to show that
he would be ready, and Tom felt a joy in his heart as he realized that
his chum was uninjured.

Down to the ground went Tom, and he guided his machine toward Jack,
standing beside his own damaged craft, waiting. Suddenly there was a
sharp report, and Tom saw Jack's machine burst into flames.

"He fired into the gasolene tank!" thought Tom. "That's the boy! He
isn't going to let the Huns get his machine and the maps and
instruments. Good!"

Jack leaped back from the blaze that suddenly enveloped his aeroplane
and then ran toward Tom's machine. As he leaped upon the engine hood,
which he could do with little more risk than boarding a swiftly moving
trolley car, there was a burst of rifle fire from the cavalry, some of
which had reached the scene.

Jack gave a gasping cry, and fell limp. He almost slipped from the motor
hood, but with one hand Tom quickly fastened his companion's life belt
to the support and then, knowing Jack could not fall off, opened his
engine wide.

Across the ground the double-loaded craft careened, while the cavalry
opened fire.

"If they hit me now, it's all up with both of us!" thought Tom
desperately.

But though the bullets splattered all around him, and some hit the
machine, neither he nor Jack was struck again, nor was any vital part of
the machinery damaged. Poor Jack, though, seemed lifeless, and Tom
feared he had arrived the fraction of a minute too late.

Then up rose Tom's plane, up and up, the powerful engine doing its best,
though the machine was carrying double weight. But the Nieuports are
mechanical wonders, and once the craft was free of the earth it began
climbing. Fortunately there were no swift German machines near enough to
give effective chase, though some of the heavier bi-motored craft opened
fire, as did the cavalry from below, as well as some of the
anti-aircraft guns.

But Tom, keeping on full speed, soon climbed up out of danger, and then
swung around for a flight toward his own lines. He could see, ahead of
him, the fleet of French planes, going back after the raid on the big
guns. Tom's plane was the rearmost one.

Then he knew that he was safe! But he feared for Jack!

One after another, such as were left of the raiding party landed. Their
comrades crowded around them, congratulating them with bubbling words of
joy. Yet there was sorrow for those that did not return.

"Is he dead?" asked Tom, as orderlies quickly unstrapped Jack, and
prepared to carry him to the hospital. "Is he dead?"

"Alive, but badly wounded," said a surgeon, who made a hasty
examination.

And then all seemed to become dark to Tom Raymond.

"Well, Jack, old man, how do you feel?"

"Oh, pretty good! How's yourself?"

"Better, now that they've let me in to see you."

"You got the big guns, I understand."

"You mean _you_ did, too. It was as much your doings as mine. Yes, we
sprayed 'em good and proper. They won't fire on Paris again right away,
but I suppose they'll not give up the trick, once they have learned it.
But we have their number all right. Now you want to hurry up and get
well."

Jack was in the hospital recovering from several bullet wounds. They had
not been as dangerous as at first feared, but they were bad enough. Tom
had come to see him and give some of the details of the great raid,
which Jack had been unable to hear because of weakness. Now he was
convalescing.

"What's the idea of hurry?" asked Jack. "Are we going after more big
cannon?"

"No, this is a different stunt now. We're going over the Rhine."

"Over the Rhine?" and Jack sat up in bed.

"Monsieur--I must beg--please do not excite him!" exclaimed a pretty
nurse, hurrying up. "The doctor said he must keep quiet."

"But I want to hear about this," insisted Jack. "Over the Rhine! Say,
that'll be great! Carrying the war into the enemy's country for fair!"

"I'll tell you a little later," promised Tom, moving away in obedience
to an entreaty from the nurse.




CHAPTER XXIII

OFF FOR GERMANY


Whether it was Tom's news or Jack's natural health was not made clear,
but something certainly caused Jack Parmly to recover strength much more
rapidly then the surgeons had believed possible, so that he was able to
leave the hospital soon after Tom's visit.

"And now I want you to explain what you meant by saying we were to go
over the Rhine," Jack insisted to his chum. "I've been wondering and
thinking about it ever since you mentioned it, but none of them would
tell me a thing."

"No, I reckon not," chuckled Tom.

"Why, you old sphinx?"

"Because they didn't know. It's a secret."

"Can you tell me?"

"Sure! Because you're going to be in it if you are strong enough."

"Strong enough? Of course I'll be! Why, I'm feeling better every minute!
Now you go ahead and relieve my anxiety. But first tell me--have you had
any news of your father?"

Tom shook his head.

"Not a word," he answered. "I'm beginning to feel that he has been
captured by the Germans."

"That's bad," murmured Jack. "And now, have you heard anything about--"

"Bessie and her mother?" finished Tom, breaking in on his chum's
question with a laugh. "Yes, I'm glad I can give you good news there.
They are all right, and I have a letter from Bessie for you. She wants
you to come and see her."

"You have a letter? Why didn't you give it to me before? You fish!"

"It just came. And so did news about their safety."

"Then the spy didn't get 'em after all."

"Oh, yes, he got 'em all right! But he bungled the job, or rather,
Bessie bungled it for him. They were rescued, and the spy was locked up.
We're to go to Paris to see them. They'll tell us all about it then."

"But what has that to do with our going over the Rhine?"

"Nothing. We're to go to Paris for a rest, and to get in shape for a big
effort against the Germans. I'll tell you about it."

"Forge ahead, then."

Tom got up to look at the doors and windows of the French cottage back
of the lines, where Jack had been moved to complete his recovery. Tom
and Jack, after the sensational raid, had been given leave of absence.

"I just want to make sure no one hears what I say, for it's a dead
secret yet," Tom went on. "But this is the plan. The French have several
of the biggest and newest Italian planes--planes that can carry half a
dozen men and lots of ammunition. Our aerodrome is going to be shifted
to the Alsace-Lorraine front, and from there, where the distance to
German territory is shorter than from here, we are to go over the Rhine
and bombard some of their ammunition and arms factories, and also
railroad centers, if we can reach 'em."

"Good!" cried Jack. "I'm with you from the fall of the hat!"

"First you've got to build up a little," stated Tom. "There is no great
rush about this Rhine-crossing expedition. A lot of plans have to be
perfected, and we've got to try out the Italian plane. And, before that,
we are to go to Paris."

"Who says so?"

"Major de Trouville. He's greatly pleased with the result of the raid on
the big German guns, and says we're entitled to a vacation. Also he
knows I want to make some more inquiries about my father. But I fear
they will be useless," and Tom sighed.

"And are we to go to see Mrs. Gleason?" asked Jack.

"Yes. And Bessie, too. They'll tell us all that happened."

A few days later, having received the necessary papers, Tom and Jack
were once more on their way to the capital. And this time they did not,
with others, have to suffer the danger and annoyance of the long-range
bombardment. It was over for a time, but there was no guarantee that the
Germans would not renew it as soon as they could repair the damage done
to their giant cannons.

The boys found Bessie and her mother in lodgings in a quiet part of
Paris, and were met with warm greetings. Then the Gleasons told their
story.

They had been inveigled out of their lodgings by the false note from the
boys, and had immediately been taken in charge by the spy, who, it was
proved, was an agent of the infamous Potzfeldt. But Bessie, after
several days' captivity in an obscure part of the great city, managed to
drop a letter out of the window, asking for help.

The police were communicated with, and not only rescued Mrs. Gleason and
her daughter, but caught the spy as well, and secured with him papers
which enabled a number of Germany's ruthless secret service agents to be
arrested.

It was because of the necessity for keeping this part of the work quiet
that no word of the rescue of Bessie and her mother was sent to the boys
until after the big gun raid.

There was much to be talked about when the friends met once more, and
Mrs. Gleason said she and Bessie were going back to the United States as
soon as they could, to get beyond the power of Potzfeldt.

As Tom had feared, there was no news of his father, but he did not yet
give up all hope.

"If he's a prisoner there's a chance to rescue him," he said.

The time spent in Paris seemed all too short, and it came to an end
sooner than the boys wished. Jack was almost himself again, though he
limped slightly from one of the German bullets in his leg. There was
every hope, however, that this would pass away in time.

Good-byes were said to Bessie and her mother, and once more the two Air
Service boys reported to their aerodrome. There they found not one, but
two, of the big Italian machines, which are capable of long flight,
carrying loads that even the most ponderous bombing plane would be
unable to rise with.

Preparations for the bold dash into the enemy's country went on
steadily and swiftly. Tom and Jack were trained in the management of the
big birds of the air, and though it was essentially different from what
they had been used to in the Nieuports and the Caudrons, they soon
mastered the knack of it, and became among the most expert.

"I believe I made no mistake when I picked them to be part of the
raiding force," said Major de Trouville.

"Indeed you did not," agreed Lieutenant Laigney. "Their work in
discovering the big guns, and their help in silencing them, showed what
sort of boys they are."

And finally the day came when those who were to take part in the raid
across the Rhine were to proceed to a point within the French lines from
which the start was to be made.

Other Italian planes would await them there, and there they would
receive final instructions.

They bade farewell to their comrades in Camp Lincoln, and were given
final hand-shakes, while more than one, struggling to repress his
emotion wished them "_bonne chance_!"

This raid against one of the largest and most important of the German
factory and railroad sections had long been contemplated and details
elaborately worked out for it. The start was to be made from the nearest
point in French-occupied territory, and it was calculated that the big
Italian machines could start early in the evening, cross the Rhine,
reach their objective by midnight, drop the tons of bombs and be back
within the French lines by morning.

Such, at least, was the hope. Whether it would be realized was a matter
of anxious conjecture.

At last all was in readiness. The final examinations of the machines and
their motors had been made and the supplies and bombs were in place.

"Attention!" called the commander. "Are you ready?"

"Ready!" came from Tom, who was in command of one machine.

"Ready!" answered Haught, who was in charge of the second.

"Then go, and may good fortune go with you!"

There was a roar of the motors, and the big, ponderous machines started
for Germany.

Would they ever reach it?




CHAPTER XXIV

PRISONERS


Under the evening stars, the two big Italian machines slowly, and, it
must be said, somewhat ponderously, as compared with a speedy Nieuport,
winged their way toward the German river, behind which it was hoped,
some day, to drive the savage Huns.

"What do you think?" asked Jack of his chum, for in these latest
machines, by reason of the motors being farther from the passengers, and
by means of tubes, some talk could be carried on.

"I don't know just what to think," was the answer. "So much has happened
of late, that it's almost beyond my thinking capacity."

"That's right. And yet I can guess one thing you have in mind, Tom, old
scout."

"What is it?"

"Your father! You're hoping you can rescue him."

"That's right, I am. And as soon as this drive is over--if we come back
from it with any measure of success, and I can get a long leave of
absence--I'm going to make a thorough search for him."

"And I'll be with you; don't forget that!"

There was not time for too much talk of a personal nature, as Tom and
Jack had to give their attention to the great plane. The motors were
working to perfection, and with luck they should, within a few hours, be
over the great German works, which they hoped to blow up.

Tom was in charge of the plane, but he had Jack and others to help him,
and there was a certain freedom of movement permitted, not possible in
even the big photographing or bombing planes.

Down below little could be seen, for they were now over the French and
German trenches, and neither side was showing lights for fear of
attracting the fire of the other.

But Tom and Jack had been coached in the course they were to take and,
in addition, they had a pilot who, a few weeks before, had made a
partially successful raid in the region beyond the Rhine, barely
escaping with his life.

And so they flew on under the silent stars, that looked like the small
navigating lights on other aeroplanes. But, as far as the raiders knew,
they were the only ones aloft in that particular region just then. They
had risen to a good height to avoid possible danger from the German
anti-aircraft guns. There was not much danger from the German planes,
as, of late, the Huns had shown no very strong liking for night work,
except in necessary defense.

Off to the left Tom and Jack could see the other big Italian plane, in
charge of Haught. It carried only small navigating lights, carefully
screened so as to be invisible from below.

"I suppose you understand the orders," said Tom, speaking to Jack.

"Well, we went over them; but it wouldn't do any harm to refresh my
memory. You're to be in general charge of the navigation of the plane,
and I'm to see to dropping the bombs--is that it?"

"That's it. You'll have to use your best judgment when it comes to your
share. I'll get you over the German works and railroad centers, as
nearly as I can in the dark, and then it will be up to you."

"I hope I don't fail," said Jack, speaking through the tube.

"You won't. Don't get nervous. Any kind of a hit will throw a scare into
the Huns, and make them feel that they aren't the only ones who can make
air raids. But in this case we're not bombing a defenseless town, and
killing women and children. This is a fortified place we're going over,
and it's well defended."

"Some difference," agreed Jack.

"And if we can get some direct hits," went on Tom, "and blow to
smithereens some of their munition or armament factories, we'll be so
much nearer to winning the war."

And that, in brief, was the object of the flight over the Rhine.

Once more the boys fell silent.

On and on swept the planes. Whether the Germans beneath were aware of
the danger that menaced them, it is impossible to say. But they made no
attempt to fire on the Italian craft. Probably because of the darkness,
and owing to the great height at which they flew, the Huns were in
ignorance of what was taking place.

On and on in the night and beneath the silent stars they flew. Now Tom
and the pilot began watching for some landmark--some cluster of lights
which would tell them their objective was within sight. But for another
hour nothing was done save to guide the big craft steadily onward.

Once, as Jack looked down, he saw what seemed to be a city, and he
thought this might be the place where the great factories were situated.

"No, it's an important town," Tom said, in answer to his chum's
inquiries, "but it is only a town--not a fortress, as the Huns call
London. That isn't fair game for us."

But half an hour later the pilot spoke sharply, and gave an order. He
pointed downward and ahead and there a faint glow, and one that spread
over a considerable area, could be made out.

"That is where we are to drop the bombs," said Tom to Jack.

The other machine, which had flown somewhat behind the one in which were
the two chums, now swerved over at greater speed. Her pilot, too, had
picked up the objective.

And now began the most dangerous part of the mission. For it would not
do to drop the bombs from too great a height. There was too much risk of
missing the mark. The planes must descend, and then they would be within
range of the defensive guns.

But it had to be done, and the order was given. As Jack and Tom went
lower, in company with the other plane, they observed that they were
over a great extent of factory buildings, where German war work was
going on.

And now the noise of their motors was heard. Searchlights flashed out
below them, and stray beams picked them up. Then the anti-aircraft guns
began to bark.

"We're in for a hot time!" cried Jack.

"You said it!" echoed Tom, as he steered the great plane to get into an
advantageous position.

Through a glare of light, and amid a hail of shots, the great airships
rushed down to hover over the German factories. They would not let go
their bombs until in a position to do the most damage, and this took a
little time.

"How about it, Tom?" asked Jack, for he was anxious to begin dropping
the bombs.

"Just another minute. We'll go down a little lower, and so do all the
more damage."

And down the airship went. She was hit several times, for shrapnel was
bursting all around, but no material damage was done, though one of the
observers was wounded.

"Now!" suddenly signaled Tom.

"There they go!" shouted Jack, and he released bomb after bomb from the
retaining devices.

Down they dropped, to explode on striking, and the loud detonations
could be heard even above the roar of the motors. Tom noted that the
other machine was also doing great destruction, and he saw that their
object had been accomplished.

Several fires broke out below them in different parts of the factory
property, and soon the Germans had to give so much attention to saving
what they could, that their fire against the hostile airships noticeably
slackened.

"Any more bombs left, Jack?" asked Tom.

"A few," answered his chum.

"Let 'em have it now. We're right over a big building that seems to be
untouched."

Down went the bombs, and such an explosion resulted that it could mean
but one thing. They had set off a munition factory. This, as the boys
afterward learned, was the case.

So great was the blast that the great plane skidded to one side, and a
moment later there came a cry of alarm from some of the crew.

"What's the matter?" shouted Tom.

"Out of control," was the answer. "One of the motors has stopped, and
we've got to go down."

"Can't we go up?"

"No!" was the despairing answer. "We've got to land within the German
lines."

And down the great Italian plane went, while her sister ship of the air
sailed safely off, for it would have been foolhardy for her to have
tried to come to the rescue.

The crew worked desperately to send their craft up again, but it was
useless. Lower and lower she went, fortunately not being fired at, so
great was the confusion caused by the destruction of the factories.

"Take her down as far away as possible from this scene," said Tom to one
of his men. "If we land in a lonely place we may be able to make repairs
and get up again."

"I will," was the answer.

Through the light from the burning buildings, a spot in a level field
was selected for a landing. And down the Italian plane went.

A hasty examination showed little wrong with the motor, and this little
was quickly repaired.

But the hope of getting the airship to rise again was frustrated, for
just as the raiding party was about to take its place in the machine
again, a company of German soldiers came running over the fields,
demanding the surrender of the intrepid men of the air. There was
nothing else to do--no time to set the craft on fire.

So it fell into the hands of the Germans! Tom, Jack and the others were
prisoners!




CHAPTER XXV

THE ESCAPE


"Well, this is tough luck!"

"Tough is no name for it, Jack. It's the worst ever! I don't suppose
they'll do a thing to us after what we did to the factories."

"No. We certainly scotched 'em good and proper. Everything went off like
a tea party, except our coming down. And we could have gotten up again,
only those Germans didn't give us a chance."

"You can't blame 'em for that."

"No, I suppose not. But it's hard lines. I wonder why they're keeping us
here?"

Tom and Jack were talking thus while held prisoners by the Germans,
after the airship raid over the Rhine. It was an hour after they had
been forced to descend.

So sudden had been the rush of the German infantry that no chance was
had to destroy the great Italian plane, and it, and all the crew,
including the two Air Service boys, had been overpowered, and disarmed.
They were thrust into what might pass for a guardhouse, and then, a
guard having been posted, the other soldiers hurried back to aid in
fighting the fire which had been started in the great factories, and
which was rapidly spreading to all the German depot.

"Well, it's worth being captured to think of the damage we've inflicted
on the Huns this night," observed Jack, as he stood with Tom in the
midst of their fellow prisoners.

"That's right. We don't need to be ashamed of our work, especially as
we've helped put the big guns out of business. I reckon the Boches won't
treat us any too well, when they know what we've done."

"And the other plane got away, they tell me," observed one of the French
crew.

"Yes, I saw her rise and light out for home, after dropping a ton or so
of bombs on this district," said Tom. "Well, she can go back and report
a success."

"And let the folks know we're prisoners," said Jack. "It's tough luck,
but it had to be, I suppose! We're lucky to be alive."

"You said it," agreed Tom. "We came through a fierce fire, and it's a
wonder that we weren't all shot to pieces. As it is, the plane is as
good as ever."

"Yes, and if we could only get out to it, and start it going we could
escape," observed one of the Frenchmen bitterly. "There she is now, on
as good a starting field as one could wish!"

From their stockade of barbed wire they could look out and see, by the
glare of the flames, that the great plane stood practically undamaged. A
good landing had been made, but, unfortunately, in the midst of the
German ammunition depot section.

"Whew, that was a fierce one!" exclaimed Jack, as a loud explosion
fairly shook the place where they were held prisoners. "Some ammunition
went up that time."

Indeed the explosion did seem to be a disastrous one, for there was
considerable shouting and the delivering of orders in German following
the blast. Many of the soldiers who had been summoned to stand on guard
about the barbed-wire stockade, where the captured raiders were held,
were summoned away, leaving only a small number on duty.

But as these were well armed, and as the wire stockade was a strong one,
and as Jack, Tom and the others had nothing with which to make a fight,
they were as safely held as though guarded by a regiment.

"There goes another!" cried Jack, as a second detonation, almost as loud
as the first, shook the ground. "Some of our bombs must have been time
ones."

"No," said Tom. "What's probably happening is that the fire is reaching
stores of ammunition, one after the other. This whole place may go up in
a minute."

That seemed to be the fear on the part of the Germans, for more orders
were shouted, and all but two of the soldiers guarding the captives were
summoned away from the wire stockade.

There had been a bright flare of fire after the second explosion, but
this soon died away, and the shouts and commands of the officers
directing the fire-fighting force could be heard.

Tom and Jack were standing near the wire barrier trying to look out to
see what was going on beyond a group of ruined factory buildings, and at
the same time casting longing eyes at the great aeroplane which seemed
only waiting for them, when the two boys became aware of a figure which
appeared to be slinking along the side of the stockade. This figure
acted as though it desired to attract no attention, for it kept as much
as possible in the shadows.

"Did you see that?" asked Jack of his churn in a low voice.

"Yes. What do you make it out to be?"

"He isn't a German soldier, for he isn't in uniform. Have any of our
crowd found a way out of this place by any chance?"

"I don't know. If they have--"

The boy's words were broken off by a low-voiced call from the slinking
figure. It asked:

"Are you American, French or English prisoners?"

"Some of each variety," answered Jack, while at the sound of that voice
Tom Raymond felt a thrill of hope.

"If you get out, is there a chance for you to get away in your
aircraft?" the figure in the shadow questioned. "Be careful, don't let
the guards hear."

"There are only two, and they're over at the front gate," said Jack, as
Tom drew nearer in order better to hear the tones of that voice. "They
seem more occupied in watching the fire than in looking at us," went on
Jack.

"Good!" exclaimed the man. "Now listen. I am an American, and I was
captured by the Germans, through spy work, some time ago, in Paris. I
was brought here, and they have been trying to force me to disclose the
secret of some of my inventions.

"I refused, and was sentenced to be shot to-morrow. But to-night you
fortunately raided this place. My prison was one of the places to be
blown up, and I managed to escape, without being hurt much. I heard that
they had captured the crew of one of the airships, and I came to see if
I could help. They don't know yet that I'm free, and I have two hand
grenades.

"Now listen carefully. I'll throw the grenades at the front gate. By
shattering that it may be possible for you to get out. The two sentries,
will have to take the chances of war. If you get out can you get away in
your airship?"

"Yes, and we can take you with us--Dad!" exclaimed Tom in a tense
whisper.

"Who speaks?" hoarsely asked the man in the shadow of the stockade.

"It is I--your son--Tom Raymond! Oh, thank heaven I have found you at
last!" exclaimed Tom, and he tried to stretch his hand through the
barbed wire, but it was too close.

"Is it really you, Tom, my boy?" asked Mr. Raymond in a broken voice,
full of wonder.

"Yes! And to think I should find you here, of all places!" whispered
Tom. "I won't stop now to ask how it happened. Can you throw those
grenades at the gate?"

"I can, and will! Tell your friends to run back to the far end of the
stockade to avoid being hurt. I can crouch down behind some of the
ruined walls."

Tom and Jack quickly communicated the good news to their friends, that a
rescue was about to be attempted. It was a desperate chance, but they
were in the mood for such.

The two guards alone remaining of the force that had been posted about
the stockade were so distracted by the fires and explosions around them,
and so fearful of their own safety, that they did not pay much attention
to the prisoners. So when Tom and Jack passed the word, and the airship
crew ran to the end of the stockade and crouched down to avoid injury
when the hand grenades should be exploded, the guards paid little
attention.

Mr. Raymond, for it was indeed he, crawled to a position of vantage, and
then threw the hand grenades. They were fitted with short-time fuses,
and almost as soon as they fell near the stockade gate they exploded
with a loud report. A great hole was torn in the ground, and one of the
sentries was killed while the other was so badly injured as to be
incapable of giving an alarm. The gate was blown to pieces.

"Come on!" cried Tom to his friends, as he saw what his father had done.
"It's now or never, before they rush in on us."

They raced to the breach in the wire wall of the stockade. Mr. Raymond,
springing up from where he had taken refuge behind a pile of refuse, was
there to greet those he had saved, and he and Tom clasped hands silently
in the gloom that was lighted up by the fires and the bursts of light
from the munition explosions.

"Oh, Dad! And it's really you!" murmured Tom.

"Yes, my boy! _I_ never expected to see you again. Did you know I was
here?"

"I never dreamed of it! But don't let's stop to talk. We must get to the
airship at once! But you are wounded, Dad!"

"Nothing but a splinter from a bomb. It's only a cut on the head, Son,"
and Mr. Raymond wiped away the blood that trickled down on his face.

The newly freed prisoners lost no time. With a rush they made for the
airship. If they could only get aboard and start it off all would yet be
well. Could they do it?

Momentary silence had followed the detonation of the two hand grenades
thrown by Mr. Raymond, but now there came yells of rage from the
Germans, disclosing that they had become aware of what was going on.

"Lively, everybody!" cried Tom, as he led the way to the big plane.

"Are we all here?" asked Jack.

A rapid count showed that not one of the brave force had been left
behind.

"Is there room for me?" asked Mr. Raymond.

"Well, I should say so!"

"If there isn't I'll stay behind," cried Jack.

"No you won't!" exclaimed Tom. "There'll be room all right!"

The running men reached the plane just as they could see, in the light
of the burning factories, a squad of Germans rushing to intercept them.
In haste they scrambled aboard, and pressed the self-starter on the
engine. There was a throbbing roar, answered by a burst of fire from the
German rifles, for the place had been so devastated that no machine guns
were available just then.

"All aboard?" asked Tom, as he stood ready to put the motors at full
speed and send the craft along the ground, and then up into the air.

"All aboard--we're all here!" answered Jack, who had kept count. And Mr.
Raymond was included.

Then with a louder roar the motors jumped to greater speed, and the
Italian plane started off. In another instant it rose into the air.

With yells of rage the Germans even tried to hold it back with their
hands, and, failing, they increased their fire. But though the plane was
hit several times, and two on board shot, one later dying from his
wounds, the whole party got off. A few minutes later they were above the
burning factories, and had a view of the great destruction wrought on
the German base. So completely destroyed was it that few defense guns
were left in condition to fire at the aeroplane.

"Well, we did that in great shape!" exclaimed Jack, as they were on
their way over the Rhine again.

"Couldn't have been better," conceded Tom. "And, best of all, we have
dad with us."

"How did it all happen?" asked Jack.

"I don't know. We'll hear the story when we are safe in France."

And safe they were as the gray morning broke. They arrived just as the
crew of the other plane were relating, with sorrow, the fall of Tom,
Jack and their comrades, and the rejoicing was great when it was known
they were safe, and had not only outwitted the Huns, but had brought
away a most important prisoner.

"And now let's hear how it all happened," begged Major de Trouville,
when the injured had been made as comfortable as possible. There were
three of these, and one dead on the plane that returned first.

The story of the attack on the German base was given in detail, and then
Mr. Raymond took up the tale from the point where he had landed in
Europe.

He had started for Paris, just as he had written Tom, and had taken
lodgings in the Rue Lafayette. He went out just before the starting of
the bombardment by the big gun, and so escaped injury, but he fell into
the hands of some German spies, who were on his trail, and who
succeeded, after having drugged him, in getting him into Germany.

The spies had succeeded in getting on the trail of a new invention Mr.
Raymond had perfected, and which he had offered to the Allies. He had
come to Paris on this business. The Huns demanded that he devote it to
their interests, but he refused, and he had been held a prisoner over
the Rhine, every sort of pressure being brought to bear on him to make
him accede to the wishes of his captors.

"But I refused," he said, "and they decided I should be shot. Whether
this was bluff or not I don't know. But they never got a chance at me.
In the night I heard, in my prison, the sound of explosions, and I soon
realized what had happened. It was your bold airship raid, and one of
the bombs burst my prison. I ran out and saw the Italian planes in the
air.

"What then happened you know better than I, but what you probably do not
know is that you very likely owe your lives to a dispute that arose
between the German infantry and the air squadron division," and he
indicated Tom, Jack and the others who had been in the stockade.

"How was that?" asked Jack.

"The airmen claimed you as their prey, and the infantrymen said they
were entitled to call you theirs. So, even in the midst of the fire and
destruction, the commandant had to order you put in the stockade until
he could decide whose prisoners you were. The infantrymen said they had
captured you, but the airmen said their fire had brought down your
plane."

"Well, that was partly true," said Tom. "But it was an explosion from
below that knocked us out temporarily. But we're all right now. And so
are you, aren't you, Dad?"

"Yes, but I worried a lot, not knowing what had happened to you, Tom,
and being unable to guess what would happen to me. I was in the hands of
clever and unscrupulous enemies. How clever they were you can judge when
I tell you they took me right out of Paris. Perhaps the bombardment made
it easier. But tell me--what of the big guns?"

"Some of them are out of commission, thanks to your brave boy and his
comrades," said Major de Trouville.

"Good!" cried Mr. Raymond. "Some rumor to that effect sifted in to me
there, but it seemed too good to be true. The Germans must be wild with
rage."

"I guess they are," admitted Jack.

"And it would have gone hard with you if they had found you were the
ones responsible," went on Tom's father. "As soon as I was out of my
prison and saw the state of affairs, I managed to get the grenades, and
I decided to rescue the airship men if I could. I never dreamed my own
son would be among them, or that I might be brought away."

And now it but remains to add that because of their exploits Tom and
Jack received new honors at the hands of the grateful French, and,
moreover, were promoted.

Mr. Raymond, who had steadfastly refused to reveal the secret of his
invention to the Huns, immediately turned it over to the Allies.

Word of Mr. Raymond's safety and of the success of Tom and Jack was sent
to those in Bridgeton, and that city had new reasons for being proud of
her sons.

But the war was not over, and the Germans might be expected to develop
other forms of frightfulness besides the long-range guns, which, for the
time being, were silenced. However, the destruction of the factories and
ammunition stores by the raid over the Rhine was a blow that told
heavily on the Hun.

"Well, it seems there's another vacation coming to us," said Tom to Jack
one morning, as they walked away from the breakfast table in their
mess.

"Yes? Well, I think we can use it. What do you say to a run into Paris
to see your father? He's surely there now, and I'd like to have a talk
with him."

"With--_him?_" asked Tom, and there was a peculiar smile on his face.

"Of course," said Jack.

"Oh," was all Tom answered, but he laughed heartily.

And so, with Tom and Jack on their way to Paris, for a brief respite
from the war, we will take leave of them for a time. That they were
destined to take a further part in the great struggle need not be
doubted, for the Air Service boys were not the ones to quit until the
world had been made a decent place in which to live.

THE END