The Project Gutenberg eBook, Our Young Aeroplane Scouts in Germany, by Horace Porter

THE FIGHT IN THE AIR. Page 42.

Our Young Aeroplane Scouts
In Germany

OR
Winning the Iron Cross
By HORACE PORTER
AUTHOR OF
"Our Young Aeroplane Scouts In France and Belgium."
"Our Young Aeroplane Scouts In Turkey."
"Our Young Aeroplane Scouts In Russia."

Copyright, 1915
By A. L. Burt Company
OUR YOUNG AEROPLANE SCOUTS IN GERMANY

CONTENTS

OUR YOUNG AEROPLANE SCOUTS
IN GERMANY.

CHAPTER I.
SAVED BY QUICK WIT.

"Hold on there, I want a word with you!"

Billy Barry and Henri Trouville, the Boy Aviators, were in the act of climbing into a superb military biplane on the great parade ground at Hamburg when thus hailed by a mild looking man in citizen's attire, with face half-hidden by a slouch hat and a pair of huge, horn-rimmed spectacles.

There was a note of authority in that voice, gently tuned as it was, and behind those spectacles were a pair of eyes as keen as gimlet points.

The speaker was none other than Roque, the noted secret agent—"Herr Roque," if you please, fitting into his masquerade as a merchant having contract business with the authorities of the canvas city of aëroplane hangars.

"Come over to quarters for a few moments, young sirs, won't you?"

The polite manner of request was for the benefit of the bystanders, who had been awaiting the flying exhibit, but the slight gesture that went with the words indicated a command to Billy and Henri.

They knew Roque!

Heinrich Hume, aviation lieutenant, who usually had a good deal to say on those grounds, made no more protest than a clam at this interruption of a special aëroplane test. He simply waved two other aviators on duty into the machine, as Billy and Henri marched meekly away with the imitation merchant.

While many of the spectators marveled at the apparent breach of discipline, the lieutenant was content to let them wonder. At least, he offered no explanation.

Billy and Henri did a lot of thinking as they crossed the parade ground—there must be something brewing, or Roque would not have been so impatient as to invade the parade ground at the time he did.

Roque conducted the boys into Lieutenant Hume's private office at headquarters, closed and locked the door behind them.

Removing his spectacles, and throwing his slouch hat among the maps that littered a big table in the center of the room, the secret agent at the same time changed his form of address—the oily manner was succeeded by abrupt and stern speech, which showed the real man of brain and unlimited authority.

The secret agent had seated himself, without invitation to the boys to do likewise. They stood, facing the real Roque they knew by former experience.

"Where is Ardelle?"

Roque put the question like a pistol shot, and fiercely eyed the youngsters before him.

The point-blank query failed to reach the mark intended.

Billy looked at Henri and Henri looked at Billy, and then they both looked at Roque with never even a quiver of an eyelash. They had not comprehended what was behind the dreaded agent's snapshot at their nerves. The truth of the matter was, they did not know anybody by the name of "Ardelle."

So Billy, with a bold front, remarked: "You can't prove it by us, sir. Mr. Ardelle is not in our list of friends."

"None of that!"

Roque pointed a menacing finger at the astonished pair of youngsters.

"I have it beyond doubt that Ardelle was on these very grounds a day or two ago, and by the word of a man who could not be mistaken. Fool that he was not to be sure at the time, and only the garb of a sailor to mislead him."

Then it jointly dawned upon the minds of Billy and Henri that Anglin, the smiling secretary of the eminent director of affairs at Calais, and later in the rôle of a bubbling sailor here in faraway Hamburg, must be the Ardelle about whom Roque was talking.

They realized, too, that through their boyish delight in lending aid and a helping hand to one they had known in intimate association with that best of friends in France, they had unconsciously maneuvered themselves into a dangerous game, a slip in which meant a dance with death.

A tissue message from this very suspect that Roque was so eager to apprehend even then burned against the breast of Henri, a little wad of paper that now represented the price of the world to a pair of bright boys.

Condemned of mixing in the battle of wits between the grim Roque and his strongest wily rival from over the sea, and it were better that the young aviators had tumbled from their aëroplane during the last high flight.

But those who traveled in spirit with Billy Barry, the boy from Bangor, Maine, U. S. A., and his plucky teammate, Henri Trouville, in France and Belgium, can assure that it is no easy task to catch this pair napping.

The courage tempered by that first and continuous baptism of fire was good steel for any emergency.

Roque owned to himself that his quickfire had failed to get results. His informant, himself just returning from a secret mission on hostile soil, had noted the movements of the sailor suspect on the aviation exhibit day, and also the attitude of Henri at the moment when the message was passed. But of the message itself, the reporting agent could have no knowledge. He was not near enough to detect a trick so deftly done.

Roque and Ardelle had measured brains many a time and often, but heretofore at long range, and the former had never seen the latter in person. Had such been the case, the French agent's invasion of the empire would have ended at Bremen, when these two masters of craft had both been guests at the same time of the same café.

Roque's unerring judgment had convinced him after the first question that the boys had no knowledge of the name Ardelle. Their first profession of ignorance was too real to be mere acting. The boys took care that the light that came to them as Roque proceeded did not shine in the direction of the lynx-eyed questioner.

The rigid lines in the face of the secret agent relaxed. These boys, after all, had once served him a good turn, with a skill, courage and fidelity far beyond the ordinary, and, perhaps, he was not sorry that he had apparently found them guiltless.

"Now, young sirs," said Roque, resuming the manner of the merchant, "I have another little journey in store for you. I don't know for certain that it will prove as exciting as the last jaunt we took together, when you located a shipload of guns for me, but maybe so, maybe so.

"After we have made our excuses to the lieutenant," he continued, "we will go over to my humble home in the city, where I have some new clothes for you. I do not think you are warlike enough to want to travel in any sort of uniform, especially with a simple tradesman like myself."

It was on the tip of Billy's tongue to ask Roque why he kept up that sort of talk with those who knew him without his mask, and when there was no purpose to be served, but Billy concluded that he had better let well enough alone.

A roomy carryall was in waiting at the further end of the parade ground, toward which the merry old merchant led his young friends, with a hand under the elbows of both. It was pardonable for the aviation lieutenant to grin when the trio were passing, after making their excuses.

It had not, however, occurred to Henri to smile a response. He was just then indulging in a cold perspiration, caused by a leaping thought that Roque might personally supervise their change of garments, and in that curious way of his light upon the tissue billet pinned on the inside of his (Henri's) shirt-front.

Because they had not fully understood the meaning of the dimly dashed message, Billy had suggested that they keep it for another sitting. The paper wad had not then turned into a torpedo.

Roque's house might have belonged to a retired gardener rather than to the man with the iron grip who claimed it as home. The dooryard blazed with red flowers, and the well-kept lawn was lined by earth beds spangled with blooms in colors beyond count.

"Welcome, young sirs."

Roque waved the way into a wide hall, at the end of which yawned a great fireplace. Bowing before them the boys saw the tallest man they had ever met outside of a sideshow, a very giant, who wore a long gray coat, with a good day's output for a button factory in front.

"This is my man of business, young sirs—Paul Zorn."

The "young sirs" instantly formed the opinion that Zorn would have no trouble in cracking a cocoanut between the row of glittering teeth he displayed when Roque so introduced him.

"We are going to put our young friends into store clothes, Paul. I hope you will be able to properly fit them, and it will also be my care that you do."

"Confound the man," thought Henri, "he has never since he called me out of the machine shifted his eye long enough for me to get a hand on that tissue, and now he's going to act as my valet. He's just full of suspicion."

Billy, also, had been figuring some in his mind just what would break loose if Roque should find the sailor's note in Henri's possession. All of the powers of argument this side of the North Sea would then avail nothing in the matter of convincing Roque that he had not been double-crossed.

The only crumb of comfort that Billy felt he could hope for if the drop fell was that Roque would quit his comedy acting behind the scenes for the once—but that was scant comfort, surely, under this cloud of anxiety.

The boys soon knew what Roque had meant by "store clothes," for it was a regular storehouse of the styles of all nations that the makeup magician maintained in the second floor back of his Hamburg home—uniforms galore, the garb of the fighting man in the Old World war, known under the folds of Britain's Union Jack, the Tricolor of France, the black double-headed eagle of Russia, the sable Cross of the German Empire; the attire of the dandy civilian, the sedate tradesman, the student, the clerk, the livery of house and carriage service, and, indeed, what not?

"A nice little collection, young sirs," observed Roque, which remark again prompted the giant Zorn to display his mouthful of shining molars.

"How do you think Paul would look in this outfit?"

Roque indicated on the display rack a regulation English uniform of olive drab, with puttees, and a cap of the traditional French arms shape, but of khaki color.

Even if the boys had been in the mood to say that Zorn would look like the Eiffel tower in any sort of uniform, Roque gave them no time to break in upon his humor.

"Nothing like keeping up-to-date, young sirs, in my business. It was only a few weeks ago that this new style French soldier first appeared in Havre. And here we can make his mate in a minute or two."

This cat and mouse play was wearing on Billy and Henri. Free of anxiety, they might have enjoyed digging into the maze of disguises as they would the pages of a popular detective story, but they had a play of their own to make, and no chance yet to make it.

"Now, Paul, how will we fix up these young flyers for a bit of ground work? Something plain, yet neat, I think, will do for the sons of Doctor Blitz—I am Blitz to-morrow, I believe, Paul?"

Zorn simply showed his teeth. He was not expected to answer.

"Now, my bird boys, get out of those uniforms and I'll make a pair of likely students out of you. Do you prefer Heidelberg, the School of Arts, or the Conservatory? No matter, though, it is just a shift for a short journey, and I guess I can make you up to pass muster."

All the time Roque was chatting principally for the amusement of himself and Paul, his hands were busy sorting a pile of clothing and he was ready to start a couple of young Blitzes into society in the most finished style—from glazed cap to shiny shoes.

It was just at this moment that Billy was seized suddenly with a fit of laughter, and his high glee was directed at Henri.

"Won't you set 'em going in that layout!" he howled.

With that he made a jump for his chum, as if to hurry the process of transformation. The playful effort commenced at the throat and scattered a few buttons. Henri resisted the attack, and for a second or two held Billy in close arm lock—time enough for the assailant to get a pin-jab in the thumb, and a wad of tissue paper in the clench of four fingers!

Roque viewed the antics with a frown of impatience, but the assistant of grenadier size roared his approval of the fun.

Henri was brisk enough then in taking off the old for the new, and by the time Billy commanded attention there was no occasion for worry.

Billy had swallowed the tissue!

CHAPTER II.
A STIRRING HOLIDAY.

To be rudely routed out of a snug nest in a feather bed at 3 o'clock in the morning—a morning with a real chill in it—is not a desirable experience for the average house-bred boy, and even such seasoned campaigners as Billy Barry and Henri Trouville were inclined to grumble when the giant Zorn yanked the covers from their downy couch and gruffly ordered them to get up and dress, and to make haste about it.

By the pale gleam of a couple of candles, and the slight warmth from a newly kindled fire in a white china stove, the "Blitz boys" made their toilets of the interesting characters they were to assume.

"What time is it anyway?" yawned Henri.

"I guess I'm not good enough in higher mathematics to figure it out for you," growled Billy, as he tussled with leather shoestrings that tied, he said, "seven ways for Sunday."

The voice of "Dr. Blitz" sounded at the foot of the stairway, in the lower regions of the house. There was no "young sirs" about it. The "good merchant of Hamburg" was on vacation.

"Crawl lively there, you snails," were the words that ascended.

"Wonder what tip he is working on now?" whispered Billy.

"You will never know until you get to it." Henri had before been impressed with the fact that Roque was not in the habit of springing until he got on the board.

"Good morning, Dr. Blitz," was Billy's cheery greeting to the man who was making hasty breakfast at a table drawn up before a crackling fire in a big brick cavern. He could not have testified from side view that it was Roque, so he took a chance on "Blitz."

Along with a gulp of coffee the imposing person addressed shot a remark in German over his shoulder, which Henri afterward explained to Billy was very near to profanity.

The boys edged into chairs at the table, but missed a round of muffins through staring at the "doctor."

The merchant masquerade was wholly outclassed by this new display of the make-up art.

Billy wanted to say "ring the night bell," but sheer admiration kept him silent.

Whether it was the combined effects of the steaming coffee, hot muffins, and a big black cigar that followed, or the silent tribute in the eyes of his young guests, it was, nevertheless, a speedily noted fact that Roque was thawing into more gracious manner.

"I suppose you know that it is only a few hours now until Christmas, and we must find some special way to observe it."

Billy and Henri could not get the straight line on Roque's remark, but later realized that the holiday was of the like they had never before passed.

With a cutting wind from off the icy flow of the mighty river Elbe in their faces, the boys followed their leader to the docks, where they boarded a small craft, evidently built for speed, which had steam up and manned for instant start.

The captain was the same who commanded the deck when the boys had accompanied Roque on a previous exciting excursion. This official, standing at attention, stiff as a ramrod, gave no visible mark of recognition as the passengers boarded the boat, but Billy could have sworn that he saw something like a twinkle in the captain's right eye when they passed the gangplank.

"No use asking where we are bound for," lamented Henri.

"Not a bit of use," agreed Billy.

They were out of earshot of Roque, whose tall form, in rusty black, was outlined in the dawnlight near the wheel of the churning steamer.

The first intimation of what was to be their next landing place came in the word "Cuxhaven," passed by one sailor to another. The talk was in rapid German, but Henri caught the drift of the conversation without difficulty.

"By George," he whispered to his chum, "Cuxhaven is the place mentioned in Anglin's message."

"You mean Ardelle's message," corrected Billy.

"That's right," chuckled Henri. "I forgot that Anglin had become the big noise. Yes, it's the very place," he continued, "and it's a great naval base."

"It's a safe bet that Roque never hits a trail that isn't warm. Take it from me," and Billy was in great earnest when he said it, "there is going to be something doing."

Billy's prediction chanced, in this instance, to be more accurate than are some of the forecasts made by professionals.

It was in a dense fog that Christmas eve when the little steamer ceased chugging in the wide mouth of the Elbe, and the harbor lights burned blue. The captain condemned the weather in no uncertain terms, but Roque seemingly had no care for aught but his thoughts, as he leaned against the rail, with moody gaze fixed upon the anchored ships and the dim lines of the city beyond.

As he had shaped, not long ago, the famous raid of the German fleet upon English seaports, Roque did not underestimate the ability of his great rival, Ardelle, to open the way for a counter attack. Ardelle was known by the secret service to be on this very soil—and, surely, for some big purpose. Minnows were not sent to stir up a pool of this size.

"But they'll find no sleepy towns to blow up here," said Roque to himself.

He was all for precaution, however, and his intuition was nothing short of marvelous.

When "Dr. Blitz" and his "sons" went ashore it was the foggiest kind of a Christmas morning.

A stalwart marine attempted to put the doctor through the question paces, but the real Roque whispered a fierce something into the ear of the would-be questioner that set the latter back-tracking in a jiffy.

It was a curious and remarkable fact, but true, that an hour after the eminent secret agent and his young charges had landed in Cuxhaven, Billy's prediction, "that wherever Roque is there's something doing," was verified. Every submarine cable connecting the fortresses of this coast sounded alarm, particularly high-keyed the frantic signal from Helgoland, the fortress island, thirty-nine miles away.

Roque dropped his doctor character like a hot potato when he learned the import of the flashes. He tossed his traveling case of surgical instruments into the first open doorway he passed, and the boys were compelled to run to keep up with his long stride.

Bombs were falling from aloft, exploding among the shipping behind them, while in front one of the projectiles crashed upon a huge gas tank.

"The nerve of the devil mapped this out!"

The bitter emphasis of Roque indicated that he laid the blame of this unexpected invasion upon one head—that of Ardelle.

In the meantime, the fog-ridden atmosphere was riven by blazes of powder from the shore guns, trained upward, and the air squadron, Zeppelins and naval seaplanes, were leaping skyward to meet their kind in aërial battle.

Roque charged madly into the air station, dragging the boys after him.

A seaplane was balanced on the polished ways for the sweeping plunge.

"In the name of the Emperor!" he shouted, shouldering aside the men holding the poised craft. The same fierce whisper in the ear of the aviation lieutenant had effect identical with that upon the marine at the docks.

"Get to your places, you moonfaces"—this stern command hurled at the boys. Henri bounced into the motor section, Billy settled behind the rudder wheel, and Roque swung himself into the bow seat.

The long hull was launched with the snap of training, and with motors humming left the water without a wrench from its skimming start.

The Boy Aviators, certified masters of the air, were at their trade.

They had need of all their skill and daring that day!

"Set your course northwest," loudly ordered Roque. "Hit for Helgoland like a bolt."

"Look out that you don't hit something on the way!" shouted Henri from the rear.

The last warning was timely, if Billy had need of warning at all. There was peril in the foggy stretches.

The upper regions were literally lined with aircraft. No less than seven naval seaplanes had traveled in advance of the British warship invasion of the German bay. Having dropped all the bombs they could through the mist, they were in full return flight to the convoying vessels. Zeppelins and hostile seaplanes zigzagged on their trail, and other dirigibles and fighting craft menaced their retreat still further on.

Billy guided the seaplane he was driving to the higher strata in order to escape mix-up with the contending airships, but on the thirtieth mile recorded, Roque, who had constantly demanded distance figures, ordered a lower flight, and, the fog clearing, the flyers could plainly see on the waves far below the floating warcraft of the invaders—light cruisers, destroyers and submarines. The Germans were combating this array with aircraft and submarines, but so great was Roque's impatience to reach the fortified island that the motors were put by Henri to the limit of speed, and so that part of the conflict is not in the record of the Aëroplane Scouts.

Just off Helgoland, though, the boys had the shock of noting the crumpling of one of the British seaplanes and the end of a brave airman.

"There's no escape when death stalks you up here," sighed Billy.

"Ware away, boy," called Roque, when the seaplane hovered over Helgoland, "wait until they see the color of the bottom of the machine or we will look like a sieve before we light."

Billy "wared away," and with motors at half speed, the seaplane circled over the supposed most impregnable stronghold in the world, awaiting some signal of recognition from the fortress.

It was finally given, and Roque directed immediate descent.

On the ground once more, Billy and Henri relapsed into their dutiful service as "sons" and rear guards of the renowned "Dr. Blitz." The glazed caps had gone the way of the winds, but, as Billy put it, "we are still dressed up to beat the band."

The boys noticed that, barring a few skilled workmen and engineers, they were the only civilians in the streets that evening. They did not count Roque, for he might turn out to be a general, if occasion served.

The latter had a busy hour with the garrison officers, while the boys had an idle one, with about as much activity as is allowed a hobbled horse. It was evident that "Dr. Blitz" held this island as a holy of holies, secret even to his "sons."

"It beats me," observed Billy, edging away as far as possible from the guard stationed to keep them out of mischief, "how those Britishers ever got by this place."

"The bigger question," asserted Henri, "is, if they got by, how in the world did they ever get back?"

"That's what Roque is evidently trying to find out," intimated Billy.

The boys, while puzzling over the problem of "get by and get back," were looking at the huge fortress so tremendously fortified and noting everywhere an uninterrupted view of the sea.

They also surmised that an alert garrison was ever carefully watching the waters, day after day, night after night, hour after hour, in order not to be surprised by the powerful enemy.

"I guess the fog helped some," was the conclusion finally advanced by Billy.

"And Ardelle somewhere behind the curtain," suggested Henri.

"Oh, go 'way, man; Roque has given you the Ardelle fever."

Billy just then caught sight of Roque bearing down upon them under full stride.

"Speak of the dickens," he exclaimed, "here he comes now."

The shadows of evening continued to gather, and here and there on the island lights showed like glowworms. Roque shook hands with his officer companions. He evidently contemplated leaving in the same impetuous way that he came, but evidently not by the seaplane route.

A little steam launch tugged at its holding rope, in readiness to dash away into the misty deep. Two men muffled to the throat waited the order. Roque, with never a word to the boys, directed them by gestures to get aboard, quickly following. The launch cut through the now pitchy darkness of the Helgoland waters. With the island lights no longer visible, there could only be seen the lantern in front of the little boat, and it was a dangerous speed to be making, when the helmsman had scant view of hardly a yard ahead.

But the man at the wheel was in familiar element, to him, and the scudding vessel never came to drift movement until a glimmering signal guided to the landing place, the name of which would have meant nothing to the boys if they had had the care to inquire.

This was Christmas night in the Bight of Helgoland.

CHAPTER III.
A THRILLING MOMENT.

Under oak rafters, festooned with dried herbs, and toasting their feet at the cheery blaze of an open, roaring fire, the boys regained the Christmas spirit that had been sorely subdued in the previous dismal hour in the wave-tossed launch.

The house that had thrown open a hospitable door at the bidding of Roque overlooked the bay, and its solid walls had resisted the storms of a half-century. Mine host, Spitznagle, had he been dressed for the part, would have come very near to the Santa Claus idea, and even as he was, some of the idea hung about him in a radiant circle.

He could not, though, have possibly trimmed a tree in manner more satisfactory than he decorated the big, square table in the center of the wooden-walled dining-room, within easy distance of that first-class fire. Sizzling sausages, small mountains of crullers, fragrant coffee, mulled cider, and such like in quality and quantity, indicated a royal spread.

Roque, who had been prowling around somewhere outside for a time, suddenly preceded a gust of sleety wind into the cozy interior.

The Christmas spirit had apparently conjured up a bit of a kindly spell for him, as the iron man fitted into the scene with far less friction than the boys had anticipated, considering the mood of this driving force during the trying day.

"Snug haven, this, eh?" jovially queried the late arrival, as he spread a pair of sinewy hands over the inviting fire. "You're spoiling these youngsters, Spitz," was Roque's side remark to the blooming boniface, at the moment stirring some savory stew in a glistening copper pot. Mine Host waved a three-foot spoon in mock protest against the playful accusation.

"Nothing like that at all, my dear man," he declared in big bass tone. "I will not spoil but will cure these children of their hunger."

"Draw up, my hearties," urged Roque, setting example by dragging an oak bench alongside of the bountifully laden table. Billy and Henri jumped at the bidding.

"Where are the men that brought us over?" asked Billy, presuming upon the fact that Roque was in one of the rare periods out of his shell.

"Back, I hope, where they came from," briefly replied Roque. "Those fellows are hardy stock," he added, "and can see in the dark. Don't worry about them."

"Cuxhaven is some aircraft place, isn't it?" Henri put this wedge in the conversation.

"Perhaps it is," acknowledged the secret agent, "and" (grimly) "it may soon return the upper-story visit just paid with a cloudful of warcraft that will start a general hunt for cover."

"Had you ridden often in airships before to-day, Mr. Roque?" inquired Billy.

Spitznagle muffled a chuckle by a slight fit of coughing when he heard the question, and muttered something to himself like "donner vetter!"

Roque turned a quick eye upon the fat offender, and then gave Billy a smiling look-over before he made response.

"I confess, young man, that I have enjoyed some lofty travel before I met you, but I am willing to admit that I could not teach you and that partner of yours many new tricks in flying the heavier than air kind of machines."

"How about the Zeppelins?" cried Spitznagle, who could no longer suppress a desire to show his knowledge of Roque's prowess as an airman.

"Hold your peace, Arnold," advised the secret agent, shaking his finger at the eager champion, "my business compels me to learn a little of everything, and it's all in a day's work, anyway."

The boys were satisfied that Roque's renown had not all of it been won on the ground. Spitznagle would have made a good witness to that effect if he had been permitted to speak.

While the tall clock in the turn of the winding staircase leading to the upper floor of the old house was whanging the twelve strokes of midnight, Roque and Spitznagle pledged the fatherland with uplifted goblets, and Billy and Henri offered a silent toast to the assured soft beds upstairs.

When the early morning brought no disturbance of their inclination for a little longer time to press the pillows, the boys sleepily guessed that Roque, for once, was not in a hurry to dash into new territory. As the sun kept climbing, and still no summons from below, curiosity overruled napping, and the young aviators decided to investigate the cause of this unusual consideration of their comfort.

Halfway down the stairway their ears convinced them that the place was not deserted, for a spirited conversation in the language of the country was in progress, accompanied by a clatter of dishes, and the ever present cooking odor of sausage assailed their noses.

Besides Spitznagle, shrouded to the rib-line with his flowing apron, were three very short men and an extremely long one. The latter proved to be no other than the giant Zorn. Roque was nowhere to be seen.

The heavy host noisily hailed the late comers:

"Good morning, sleepyheads, and all this fine food waiting for you, too."

Zorn gave his best wide-mouthed grin, and then went on talking, in lower tones, however, to his short companions.

Billy and Henri made a substantial breakfast, and in doing so, hardly felt the need of the constant urging of the boss cook.

They could not imagine what had become of Roque, and as nobody volunteered to tell them, they concluded not to ask any questions.

The boys observed that one of the short men, with a large head wholly out of proportion with his stocky body, commanded much deference from the rest of the party.

Henri learned from the drift of the conversation that this determined looking individual was Capt. Groat of Friedrichshaven, the great center of Zeppelin factories, and while the captain was not in uniform he had the manner of rank.

Billy was quietly advised by his chum what the talk was about, and wagered that the two strangers were airmen.

"When these fellows commence to flock together on this coast," he asserted, "you can figure on what Roque meant when he fixed a comeback to get even for that flying raid yesterday on Cuxhaven."

The boys had withdrawn to the fireplace, and had an opportunity to exchange comments and conclusions between themselves.

"I'd like to take a whirl myself in one of those Zeppelins," was the wish expressed by Henri.

"Our flying education has been sadly neglected in that respect," admitted Billy, "but, you know, these dirigibles are among the things made only in Germany, and we're just over, so to speak."

As the morning wore away, Zorn made some remark to Capt. Groat that had attracted the latter's attention to the boys lounging at the fireplace. The captain arose from the table and approached Billy and Henri with outstretched hand.

"You speak the German?" With the question he bestowed a strenuous grip upon each of the boys.

Henri nodded, and Billy confessed by blank look that he did not know the language.

"It is easy, the English," politely assured the captain, "and we will talk it together."

Billy brightened at this. He was not fond of hearing through an interpreter.

"I hear you are the great aviators, and for so young it is wonderful."

"Thank you, sir," was Henri's modest acknowledgment.

"It is with the Zeppelin I navigate," advised the captain. "You know it not?"

"Not much," put in Billy, "though we once dangled on the anchor of one, and another time I fell with a monoplane right across the back of one of your dirigibles."

"Yes," remarked Henri, "and if it hadn't been for that, there wouldn't have been any Billy alive to tell about it."

The captain showed a disposition to continue his talk during the afternoon with the boys, but a new arrival of evident importance interrupted. This addition to the party was a much older man than the rest, wore a military cloak, and his long, gray mustache curled at the ends in close touch with his ears. As he stood at the end of the big table, now cleared of its cloth, and rested a hand, enveloped in a gauntlet, upon the shining surface, everybody in the room saluted. Over the shoulder of this distinguished guest the boys saw the face of Roque.

As if by signal, further increased by the hasty entrance of three additional numbers, the attending company ranged by equal division on each side of the table, and all followed the directing movement of the man at the head of the board in seating themselves.

Billy and Henri were the only bystanders, for though Spitznagle had not ventured to flop down upon a bench at the table, he perched himself on a high stool, completely blocking the door leading into the pantry.

One of the short men who had first appeared with Capt. Groat produced a capacious wallet, and laid out in orderly array a number of neatly folded papers which had been contained in the leather.

"This is the navigator detailed to determine air currents, sir," explained Roque to the chief figure, at whose right elbow the secret agent was stationed.

The man in the cloak fixed his gaze on the expert with the notes. The latter accepted this as permission to speak, and read in precise manner the results of close observation during a recent aërial expedition of Zeppelins, escorted by armed German biplanes, in the vicinity of Dover straits.

Henri's quick ear and thorough knowledge of the Teuton tongue put him in line of complete understanding of the report, and that it seemed preliminary to a proposed general raid of aircraft on territory with which he was well acquainted.

Billy's only satisfaction was in watching his chum's change of expression as the news sifted through the latter's mind. He could see that there was "something doing."

So intently interested was the gathering at the table in the reading, that the very existence of the youthful outsiders seemed to be forgotten.

"Good; excellent!" commented the chief.

"It's a game with double trumps." Roque held the affair at Cuxhaven as a choking memory.

"There'll be quite a fall of hot shot, I promise you, if we get started right." This was the prediction of Captain Groat.

His lieutenants from Friedrichshaven nodded their approval.

In anticipation of a telling counterstroke by their air squadron, the plan makers at the table puffed up clouds of smoke from pipes and cigars, freely distributed by the happy Spitznagle when the lengthy discussion officially ended. In the added hours, when stone mugs were passing among the thirsty, night had fallen outside, and the benches were turned to the glowing fire.

While Spitznagle was touching the tips of numerous candles with the tiny flame from a paper spiral, the empty mugs were being removed by an oddly dressed fellow, who shuffled around in carpet slippers like he was tormented with a thousand pangs of rheumatism.

The boys had boosted themselves to good lookout points on the wide window ledges, behind the lively circle around the fire.

The leather wallet and the survey notes of the expert air traveler lay separate and apart on the table, just as they had when the reading concluded.

Billy was idly watching the halting action of the queer servitor, when, to the great astonishment of the watcher, the apparent cripple, with rapid hand movement, under cover of the wiping cloth he carried, deftly lifted and concealed the papers somewhere in the scarecrow garments he wore.

It was a tense moment. The word that would have turned things upside down in that room trembled on Billy's lips. But one of those remarkable instances of mental telegraphy checked the utterance. The man who had stolen the papers felt that his action had been detected from an unexpected quarter, and his eyes lifted to the very point of danger. There was an appeal in the look—and something else, a flash of recognition that compelled a response. They were the smiling eyes of Anglin—or, as Roque would have it, Ardelle.

Billy, tongued-tied, saw the bent figure slowly shuffle toward the kitchen. He inwardly trembled at the thought of the stocky airman suddenly turning from the fireplace to seek his precious reports. He added another little shake in advance of the turmoil that was bound to be raised, anyhow, no matter how soon or how late the loss should be discovered. But the consolation of delayed discovery would be that Anglin had a chance to save his neck.

"What's the matter with you, pal?" Henri had just noticed that Billy was off color and wide-eyed as a trapped rabbit.

Billy, for caution, laid a finger on his lips. "I've seen a ghost," he whispered.

With a glance of apprehension at the group circling the fireplace, Billy leaned against the shoulder of his chum and with underbreath speed told of the presence of Anglin and the taking of the papers.

Henri was thrilled by the exciting story poured into his ear, and immediately took on his share of anxiety as to the outcome of Anglin's daring action.

Bursts of laughter resounded at the fireplace. The company was then applauding some humorous tale volunteered by Zorn, who had risen like a tower to impress the point of his story.

"Gee," murmured Billy, "will they never quit?"

"Don't fret," advised Henri, "the blow will fall in due time."

It did fall a few minutes later.

The main mover of the meeting was saying: "Gentlemen, it is nearing a new day, and there is great achievement before us. We go to prepare for it."

Benches were pushed back to clear the way, and this scraping sound had hardly ceased when the short airman, who had made the interesting report, hurried to the table for his valuable records.

The boys leaned forward in breathless suspense.

[CHAPTER IV.]
THE STOLEN PAPERS.

"My papers! The report! Has anybody seen them?"

The owner of the wallet shook it vigorously over the table, to assure himself that he had not replaced the records there, and then quickstepped the whole length and around the board, lowering his head again and again beneath the polished surface to see if the documents he was excitedly seeking could have possibly fallen on the floor.

"What's that?" cried Roque, starting forward. "You've lost the papers, you say?"

"I didn't lose them," almost shouted the airman, "they were left on the table, and if they're gone, they've been stolen."

"Hey, my friend," remonstrated Spitznagle, "we have no thieves in this house, and no enemies to the cause."

"This is no time to bandy words," roared Roque, "shut and bar the doors"—this last command directed at Zorn. The giant jumped at the bidding and sent the bolts rattling into their sockets.

The savage energy of Roque ruled all to silence. Even the power under the cloak refrained from advising.

The secret agent dismissed suspicion as to the active participants in the conference, and as to the loyalty of Spitznagle he had not the slightest doubt. The trial horses must needs be two pale-faced boys backed up against a window-sill.

Roque, with his hands deep in his pockets, a habit he had when stalking a suspect, walked around the foot of the table and stood directly in front of the pair, fixing on them that gimlet gaze he used to terrorize.

Billy and Henri, when at bay, were the most keenly alive; their nerve always served them most in the supreme test.

They faced their inquisitor without an outward tremor; their previous anxiety was known only to themselves, and now admirably concealed.

Roque realized that he had no fluttering birds in his hands, and also was aware that a search of their persons was only required to acquit or convict these youngsters of the actual theft. He knew that they had not left the room, though why he had not long ago sent them upstairs to bed was a slip of mind he could not account for. But it had occurred to Roque that the boys had been in a position to see the table all the time since the company adjourned to the fire, and whatever had happened in regard to the papers they, if not the light-fingered chaps themselves, must have witnessed the perpetration of the steal. So he changed his tactics.

"Now, boys," he began with insinuating address, "there is a very ugly situation here, and as I have always heretofore found you dependable, cannot I now depend upon you to help me clear this up?"

Henri shook his head, in denial for both. "Search us," he said.

Roque, whose remarkable judgment of human nature has before been noted, felt in an instant that the suggested search would develop nothing.

"Who took the papers then?" he fiercely demanded.

"We were not on guard duty." Billy was inclined to resent this bullying, and showed it by his answer.

"Strip them," urged the short airman, who thought he, as the loser, ought to have a word in the controversy.

Roque waved the man away, and then abruptly moved to where Spitznagle was sitting, a picture of despair.

"Who was in the house to-night besides those now present?" was the question fired at Mine Host.

"Nobody but Conrad," assured Spitznagle.

"Who the devil is Conrad?" Roque fairly jumped at this information.

"Why, a poor crippled fellow, as queer in the head as he was in the legs, that I had helping in the kitchen. He lost his job as cook on the coast line steamer Druid on account of rheumatism, and they sent him up here to me."

"'They sent him up,' did 'they?' And now when did 'they' send him up?"

"About a week ago. But what's all this about Conrad you're asking, Roque? I'll have him in, and you can judge if he is worth a moment's notice in this kind of affair." Spitznagle started for the kitchen door, Roque at his heels.

"Conrad, Conrad," called Spitznagle.

"Conrad" had flown, leaving nothing behind him but his rheumatism and a dingy apron.

"Yell till you're hoarse, you fathead," raged Roque, "and the cows will come home from nowhere before you get an answer."

While Spitznagle was staring into vacancy, Roque stormed back into the dining-room and announced:

"We've been the dupes of that spy Ardelle. Nobody but he could have gotten away with a venture like this. But" (gritting his teeth), "I'll beat him yet. I say, Vollmer" (turning to the aërial recorder now minus his records), "you have the whole thing in mind and we'll strike while the iron is hot. We may outride the warning, for he can't get it flashed from this coast."

The man in the cloak came to the front on this proposition. "The word is 'immediate,'" he proclaimed.

A speedy departure was in order, and Roque crooked a finger at the young aviators, bidding them follow.

"You are going to be mighty useful, my flying friends," he said, "and you'd better be." There was grim emphasis in these last words.

At noon the next day the boys were again tramping around after Roque in Cuxhaven. The character of "Dr. Blitz" was no longer in the play. Roque was trimly set up as an aviation lieutenant, and it was really wonderful how easily he merged into each part he assumed. "Students" no longer, Billy and Henri were happy in resuming their flying clothes.

"Best becomes our style of beauty," as Billy would have it.

There seemed to be some unforeseen reason for delay, as the aërial expedition did not start forthwith, as intended. Indeed, it did not start from Cuxhaven at all. It might have been that Ardelle's theft of the guide records had put a spoke in the German wheel, but as to that the boys could only hazard a guess.

It was on the twentieth day after the adventure in the house of Spitznagle that the young aviators again had the opportunity of operating a seaplane with Roque as directing passenger, and the uninterrupted flight brought them to the island of Amesland, for though Cuxhaven was counted as the airship base, it evidently was the intent to project the return attack on the English coast from the out-to-sea point before named.

What an array of the warcraft of the "upper deep"—the great dirigibles, seaplanes, destroyer, artillery spotter and scout aëroplanes. The boys were in their element. Even Roque had a smile for their enthusiasm. It was not the war spirit that animated Billy and Henri—they reveled in the show as airmen delighted with the life.

In this camp were none but the suicidally brave type of fighters, and it was only that kind fit to essay the trackless line of three hundred miles over the sea. From what the boys, or, rather one of them, Henri, could learn from the camp talk, a pair of the latest Zeppelin dirigibles were to participate, but the main movers of this attack were evidently to be airships of the small, non-rigid Parseval build, for bomb work. The truth of the matter was, the young aviators, at the order of Roque, were so taken up with the tuning of a seaplane just before the fleet went aloft that they could not have listed the starters with any degree of accuracy.

They only knew positively that they were going aloft, and their own machine would require their individual attention. About 8:30 that night the glare of a powerful searchlight from one of the German airships directed its rays over the heart of the English city of Yarmouth. Two bombs dropped almost simultaneously.

The boys saw the city below suddenly plunged into darkness. Five more bombs were hurled from the sky. The fleet then swiftly moved northeast, and more bombs crashed into the town of Kings Lynn. Roque had assumed no active part as a leader in the deadly maneuvers—his was a thinking assignment. It was midnight when the fleet turned eastward and fled back across the North Sea.

"It might have been London," muttered the secret agent, "if the game could have been played without a break."

Preparations to repel just such an invasion had been made in the great city.

Ardelle must have gotten his warning across, but the coast towns failed to heed it.

The Roque machine kept its speed when the balance of the fleet checked flight at Amesland. The secret agent was bound for Cuxhaven, doubtless to plan another tiger spring at the foe. He was all for air campaigning these days.

"You will witness the sight of your lives, you young cyclones, before last night's mist of the North Sea dries in your hair."

This significant remark on Cuxhaven docks set the boys in the highest state of expectancy. It was seldom that Roque billed anything ahead of time, and surely something extraordinary must be in the wind.

Three days later, from a dizzy height, they witnessed a sky battle without parallel in military annals, and which dimmed the memory of any of their previous remarkable experiences in the war zone.

The French coast town of Dunkirk, to which the boys had on a happy day gone by been delivered by submarine and taken away in a seaplane, was the ground center of this spectacular conquest of the air—the first of its kind in the history of the world.

Twenty hours earlier a fleet of British seaplanes had bombarded the Belgian port of Zeebrugge, held by the Germans, news of which had soon after reached the mystery man, Roque, by way of one of the innumerable channels of communication with which he kept himself constantly in touch.

The German bird craft suddenly appeared over Dunkirk like a flock of gigantic sea gulls.

Explosive missiles fell as fiery hail upon the town. The tocsin sounded in the high tower of Dunkirk church, and the blue and white flag of the town was run up.

The roar of the fort guns, firing shrapnel, was heard, and all around the German fliers white puffs were bursting, as the pilots guided their machines in low-swooping spirals.

In compliance with the snappy commands of Roque, Billy circled the seaplane to every point of observation vantage, while the secret agent viewed the action of the armored Aviatik biplanes, dashing here and there with the sun glinting on their steel sides.

"Look there!" shouted Henri, rising and clutching a stay to preserve his balance. The air was clear, and the scene was open even to the naked eye.

Billy, at the wheel, risked a glance sideways.

A squadron of British aviators, encamped on the outskirts of Dunkirk, had taken the air to engage the raiders.

One speedy biplane darted straight toward the German craft. Henri saw the aviator clutch the levers of his machine in one hand and with the other unsling a rifle, beginning fire at a German birdman below him.

A half dozen armored aëroplanes of the raiding force swarmed in upon the daring Briton. His machine was peppered with lead, and it was apparent that the man had been wounded as he dipped toward the earth to evade the encircling Germans.

Other English aviators swept into the whirling combat, and to the rescue of their wounded leader. The raiders turned toward the north, now being shrapnelled by anti-aircraft guns stationed along the coast.

Roque pointed upwards, signalling for rapid ascent, and at six thousand feet the seaplane, with tremendous burst of speed, soon overhauled and outdistanced the slower warcraft, making a wide detour over the sea, thus avoiding the volleys of rifle shots from the Allies' infantry near Nieuport.

Roque, looking at his watch, turned to Billy, just behind him, remarking:

"That much in fifty minutes is not often recorded—of these things they shall sing on the Rhine."

In Bremen the boys paid grateful tribute to rest after the strain and stress to which they had been put by their relentless taskmaster.

"I feel," said Billy, "like the hump between my shoulders is going to be permanent, and I couldn't keep my elbows down to save my soul."

"If I could only get the whirr out of my ears, I'd be satisfied," was Henri's complaint.

It was not long, however, before the boys found relief from the kinks in their backs, and were ready and eager for the next move in their adventurous careers.

Just around the corner from their hotel was the very café where they had the thrill of seeing Anglin's face in the mirror while they were dining there with Roque.

"Wouldn't it be funny if Anglin were to bob up again while we are here?"

"I think, Billy, that it would be a tragedy if Roque had any inkling of it."

"Don't you hold the thought for a moment, Henri, that you could catch the Calais weasel asleep. Oh, I say, there's a concert on downstairs," quickly concluded Billy, as the notes of violin and piano were wafted above. "Let's hunt the music."

A high tenor voice was merging into the accompaniment when the boys reached the floor below, and they saw that the singer was one of the curly-lock type, and in evening attire.

What of the eyes, though, that gleamed upon the Aëroplane Scouts as they stood in the doorway—the artistic make-up could fool them, but there was no mistaking the smiling orbs under the blackened eyebrows.

Fox tracks were mixing again!

CHAPTER V.
WHEN THE LIGHTS WENT OUT.

The vocal efforts of this new favorite had called forth round after round of applause, for good music never went amiss in Teuton territory.

Among the vigorous hand-clappers the boys noted a well-groomed man, apparently about forty, wearing an affable manner and the best clothes that the continent can produce.

Henri nudged Billy. "Size up Roque, won't you, please, and isn't he a dandy?"

Billy was first inclined to doubt the identity of their taskmaster, who a couple of hours ago was a far cry from being in the glass of fashion. Never before had the boys seen him in that sort of rig.

"You're dead right, Henri, it is the old scout. He's a corker, sure!"

This note of admiration had scarcely sounded when Roque was joined by a slender, wiry individual, also set up as a swell, with a shock of sandy hair, and sporting a monocle.

The fellow with the quizzing glass had apparently moved to get a better view of the singer, as well as to get in touch with the secret agent.

"Wonder if that's the man who spotted Anglin on the parade ground at Hamburg?"

"Don't let your imagination run away with you, Henri," advised Billy, who in speaking was careful not to indicate that his attitude was anything but careless.

The sandy-haired man was taking the same precaution, but Henri, nursing the idea that would not down, was more and more impressed with the belief that the elegant figure was seeking the measure and not the music of the warbler at the other end of the room.

If the singer had sized up the situation, it had not affected his rendering a bit of light opera that was just then exciting an encore. There was nothing at all the matter with his German or with his voice.

Nobody apparently was more delighted than Roque, and he appeared to be expressing his opinion to the wiry listener beside him.

The latter bowed politely and then sauntered toward the revolving door leading into the lounging section of the hotel, fingering a cigar as he proceeded.

Henri edged around nearer to the piano, the player of which was completing the program with a national air, the melody of many voices aiding the performance.

Billy had hardly realized the desertion of his chum when he saw that Roque had changed his position, and was standing nearest the door leading to the street. The secret agent shifted something from his hip to the sidepocket of his coat, and Billy caught the glitter of that something in the swift movement. The boy guessed then that there was trouble brewing.

In the meantime, Henri, in an innocent sort of way, pushed still closer to the pianist, who was hitting the high notes in fine style.

As he passed within a foot of the singer, now idly posing, with an elbow on the piano top, he, without turning his head, joined in the triumphant chorus, but changed two words at the climax, and "beat it" reached Anglin's ear.

The French sleuth never moved a muscle, and it was as if the warning had been passed to a man stone deaf.

Anyone posted, however, would have known that within an arm's length of Anglin was a wall switch which controlled the electric lights by which the room was so brilliantly illuminated.

Billy had just had the experience of being rather rudely thrust aside by a couple of burly troopers, who seemed inspired to get as quickly as possible into the very center of the select circle.

"Get him!"

As this command rang out the astonished pleasure seekers started a panic, as if an alarm of fire had sounded. There was a rush for every doorway, but every way of departure was blocked by stalwart guardsmen.

Billy was not among those who tried to break through the doors—he was dodging among the charging force sent in by the loud orders to "get him."

Click! The room was suddenly shrouded in darkness, penetrated a little distance only by the lights beyond the entrance of the lounging room section.

The pursuing force, working from several directions, ran into one another's arms. The pianist, familiar with the place, leaped for the electric switch, and turned on the flood of light.

Everybody was present but the singer!

Henri had a perch on the keyboard of the piano, which he had sought to save a mad tramping on his feet.

"Set you to catch a weasel," sneered Roque, as the sandy-haired man stood staring at the shattered casement of the tall window overlooking an inner court of the hotel.

"He can't get clear away," retorted the sandy one.

"Stop him then," challenged Roque. "Don't stand there like a stoughton bottle."

The pursuers scoured the building from bottom to top, and every street and alley roundabout, but it was a case of looking for a needle in a haystack.

Roque was in a black mood. Once more baffled by his cunning chief adversary, the only one he acknowledged in his own class, and on his own stamping ground—it was a bitter dose for the master craftsman.

Did he remember how he himself had spread a web over Britain, woven so finely that even Scotland Yard could not see it? Yet he rebelled at the like cut of a diamond.

"Stir your stumps," was his peremptory address to the boys, and they trotted to catch his long stride out of the hotel.

The sidewalks on both sides of the street were crowded with curious onlookers, attracted by the reported doings inside.

Roque bucked the line like a football star, and Billy and Henri followed in the cleared space without special exertion.

"He doesn't care whom he pushes," observed Billy, as he listened to angry protests along the line of travel.

Both of the boys were eager to talk over the latest disappearing act of that wonderful Anglin, but not so anxious as to take chances with Roque in earshot.

The secret agent turned into a silent side street, and stopped before a heavily grated door in the gloomy front of a solid stone building that was a skyscraper in height. Reaching through the grating, he evidently opened way of communication with the interior, for in a moment or two a glimmer of light splintered through the barred entrance, the ponderous lock creaked, and the door swung back on its massive hinges. A skull cap and a gray beard showed behind the lamp shining in the doorway. Roque pushed the boys ahead of him, and their closing in was marked by a clang behind them.

They followed their guide through a long corridor and into a modern high-power elevator, that shot noiselessly upwards. It was a circular room into which they stepped, the very tip of a tower, and a wireless telegraph apparatus was there in operation.

"How is it working?" promptly questioned Roque of an operator who was off his turn, and relieved of his headgear.

The man jumped to his feet, all attention, and replied: "There's been hardly a break for an hour, sir."

Here was one of the hidden intelligence stations that accounted in part for Roque's ability to get searching and quick information. That he should initiate the boys into his particular secret service methods indicated a determination that they should never get away from him.

As Billy said to Henri at a chance moment, "He thinks we are booked for a life job as his air chauffeurs."

They were not aware as yet that in the extensive grounds, housed at the water's edge, was the seaplane in which they had recently traveled so far, and in addition a big biplane and two monoplanes were in hangars ready for service. Also the most speedy of steam launches rested at the private wharf.

Roque was a recognized genius, like every cog in the German wheel, absolutely thorough in his methods, and the means placed at his disposal were practically limitless.

Billy and Henri had climbed into the steep embrasure of a tower window and were enjoying the magnificent view spread out before them.

"How about my imagination now?" Henri was recalling exciting incidents in the hotel. "Didn't I get the figure of the sandy man as a spotter?"

"I think you did," admitted Billy. "But," he continued, "I didn't take much stock in the idea until I saw the revolver in Roque's hand. Then I knew that the fat was in the fire."

"I gave Anglin the cue to beat it, and I did the trick by breaking into that Rhine song," exclaimed Henri. "Yet he never made a move until the yell of 'get him,' and I thought the jig was up, sure. He's the coolest hand in the business, that fellow."

"Some of these days, maybe, he'll fall a little short in one of those getaways, and that will mean a tumble into six feet of earth."

"Not he," stoutly maintained Henri, "he's the regular man with a charmed life. Say, I can't help laughing even now when I think of Spitznagle calling 'Conrad,' and the expression on Roque's face."

Billy gave Henri a kick on the foot. Roque was approaching with a sheaf of telegraph messages in his hand.

"What are you boys jabbering about? I want you to go down to the wharf with Albert and get the seaplane in trim. I'll join you in half an hour."

Albert, a strapping youth, with the breezy way of a sailor, guided the boys across the grounds to the hangar, and watched with interest the making ready of the airship.

"That's not my kind of a boat," he briskly stated, "but I'll be bound if this kind of craft didn't give us submarine workers a Christmas surprise. Ever travel in a submarine?"

"We had a ride in one that we will never forget," replied Henri, as he applied the oil can to the big motors.

Billy, busy with the steering gear, was not expected to answer, as he did not understand the question.

"It is all a question of ups and downs, anyhow," went on Albert, "bombs from above and torpedoes from below."

This trade discussion ended with the arrival of Roque, who had severed himself from style and was again in aviation attire.

"Now, my carrier pigeons, you are in for a homing flight, that is, Hamburg; and it may be some time before you again get a breath of this port."

With this assurance the seaplane was launched and took the airline for Hamburg, leaving Albert to his own devices.

The travelers soon had sight of Zorn's ever-ready grin at the home of "the well-known tradesman."

"We've been through a lot since we were last hauled out of these feathers," remarked Billy, as he bounced into the bed pillows that night.

Happily, "coming events do not cast shadows" for sound sleepers.

Roque had departed for the city before the boys charged into the breakfast room.

"He has gone to the store," announced Zorn, who uncovered his teeth an extra inch, in compliment to his own humor.

"Let's go over to see Lieutenant Hume," proposed Billy, after breakfast.

"Just the ticket," agreed Henri, "I'm crazy to get a peep at the old flying quarters again."

But Zorn objected to any move that Roque had not ordered.

The boys had to be satisfied with the prospect, for to run against Zorn would be akin to tackling a mountain.

When Roque returned, sure enough, he was again playing the merchant—horn, spectacles, and all.

"Ah, young sirs, kindly waiting for the weary worker?"

"Same old blarney," muttered Billy.

Zorn chuckled as he relieved the "merchant" of his hat and overcoat.

"Some time ago I believe I told you that here you were only balancing on the edge of the great empire, and there might be an opportunity for you to see much more of the country. The opportunity is at hand. I have been called by trade interests further afield, and as I cannot consent to a separation, you will continue as my companions."

In his hour of relaxation, Roque really enjoyed this sort of word play, and he eyed the boys to see if they appreciated the fact that all of the best actors were not on the stage.

He was sure of Zorn's sincere appreciation. This man had seen the chief in many parts.

Henri accepted the cue, and, with a profound bow, and a hand on his heart, replied in kind:

"My dear Herr Roque, we would grieve if you left us behind."

"What of you?" Roque turned to Billy.

"Oh, anything goes with me." The boy from Bangor always hit straight from the bat.

The last evening of many in Hamburg was a very pleasant one to the boys. Roque's intimate knowledge of London and Paris was displayed in entertaining way, with no reference to his own exploits as the cleverest conspirator that ever invaded court and palace. He expressed regret that he had never seen America, and induced Billy to tell about Boston and Bangor.

It may also be recorded that with this evening the boys unconsciously said good-by to the character of the Hamburg merchant. They went far with the many-sided man, but never again saw him in the rôle imposed by this big city on the Elbe.

When the boys retired they left master and man—Roque and Zorn—conversing before the fire. With the coming of the morning, the journey to the unknown began, and the Aëroplane Scouts had no idea of its purpose or their assignment in the new sphere of action.

That it would, however, include further conquest of the air they might have guessed.

CHAPTER VI.
A FLYING VICTORY.

It was a great day for the boys when they set foot in imperial Berlin, with its palaces, art galleries, museums, parliament building, monuments, magnificent parks, and over all its martial spirit.

Roque, by which name, it might be mentioned, he was not known in this heart of the empire, soon demonstrated to his charges that he was the man higher up by his manner of getting about, and the high cost of living had no worries for him.

"Who'd have thought that we would be hitched up to a ten-time winner like this?" Billy was content for the time being to be allied with power.

Among the many who answered the summons of Roque in the intelligence bureau, the young aviators were most interested in a score of blond, blue-eyed, well-set-up Saxons, renowned as Zeppelin navigators, who were destined to guide the "terrors of the air" in furtherance of another raiding plan taking form in the fertile brain of the eminent promoter of trouble for the enemy.

While the boys had faith only in the heavier-than-air machines, they conceded that the risk taken by the Zeppelin crews entitled the latter to brush elbows with the crack flyers of the other kind of bird craft. It was also true that when a Zeppelin got anywhere it was a tremendous factor in war. And it was no question but that the Fatherland had gone Zeppelin mad.

Woe betide the hostile airmen who dropped the bomb on the Zeppelin works at Friedrichshaven if Roque had the means of catching them. It was only another score that he had marked up against Ardelle, whom the master agent of the empire charged with planning this destructive performance.

"Roque said he was going to show us where these gas cruisers grow," Henri advised Billy one evening, getting this news while his chum was engaged in an argument with a Zeppelin worker.

"Something I've been wanting to see," exclaimed Billy. "I owe something to a Zeppelin, even if it is like a balloon."

This last was a sort of side swipe at the man who had been on the other side of the argument.

"There is one thing sure, these dirigibles can't camp out." This was Billy's first remark in Friedrichshaven.

He was peering into a big steel-framed shed with a glass roof which housed one of these grim engines of the air—a great cylinder flanked by platforms. This newest of the huge airships was about the length of a first-class battleship, and the opinion of the young aviator that it could not drop anywhere and everywhere like the aëroplanes he drove was not a prejudiced one.

When Henri had a look at the powerful motors he was impressed with their capacity to drink up petrol at a most appalling rate.

"What's her top speed?" he asked one of the big fellows who had traveled over from Berlin with them.

"Forty-five miles in the calm," was the reply.

"Gee!" exclaimed Billy. "We could get a seaplane home for breakfast while they were waiting supper on you!"

"Yet," claimed the Zeppelin expert, "it's the car they're all afraid of."

"It certainly does look like a scaremark," admitted Henri, who remembered a certain evening on the Belgian coast, when he was one of the company aboard a stranded hydroplane dragged ashore by the swinging anchor of a Zeppelin, which loomed overhead like a cloud, and buzzed like a million bees.

A gang of at least a hundred men swarmed about the shed when the order issued for a trial trip of the new super-Zeppelin, a sample of the fleet in course of building, and Roque carefully noted every detail of equipment.

The gas chambers were fed with pure hydrogen, no common coal gas, and many thousand cubic meters were in the flow of this one envelope filling.

"Guess they'd have to carry a hydrogen factory around with this outfit to keep it going," observed Billy, as he noted the elaborate process.

"Not that bad," advised the man at his elbow, "this gas can be transported from the factory in cylinders under pressure."

"Just think of it," put in Henri, "I heard them say just now that it took thirty gallons of petrol an hour to buzz these motors."

"Biggest thing I know in the air business. I wish Captain Johnson could see an expense bill like this. He'd have a fit." Billy would, indeed, have counted it a red-letter occasion if his old friend, and the boss airman of Dover, were really at hand to take in this show.

To go aloft in an airship about which they were not thoroughly posted was a brand-new experience for the boys, but they were not in the least degree like the proverbial cat in a strange garret. It was easy riding, and none of the guns pointed their way. Billy carried a memorandum of a British military biplane, with a record of 10,000 miles, which Henri and himself had once patched up, that had been hit by 250 rifle bullets and sixty fragments of shells. He wondered if the immense craft in which they were sailing could have floated with, proportionately, about ten times that amount of lead poured into her. But Billy, of course, did not then know much about Zeppelins.

Roque, however, was eminently well satisfied, particularly with the improved method of distributing explosives where they would do the most harm. The airship had a special armored compartment for bombs near the propellers and a big gun mounted in front to destroy aëroplanes. "Get a fleet of these over the English channel," he proclaimed, "and somebody would think that hell had been moved upstairs!"

"I'll say this much," announced Billy, "I'd take an ocean voyage for my health if I knew when they were coming."

"But if the fighting crowd over there had the date and the hour, I'll promise you that the reception your fleet would receive would be warm enough to boil an egg." This was Henri's prediction.

"We never advertise," grimly remarked Roque.

When the Zeppelin had completed her trial trip and had again been housed by the small army of workmen, Roque informed the boys that he was going to give them the chance on the morrow to show their mettle in a biplane test, which was to decide the relative merits as to the speed of two special designs.

"I am going to put you up to jockey the machine that I favor," he said, "and, mind you, the aviators that will drive against you are among the finest in our flying corps. I always pick my men by personally knowing what they can do in any line of action. They seldom fail me, and it is with you to make good."

"We're going some, Herr Roque, when we come up to your standard," replied Henri.

"See that you are 'going some' at the finish of the race to-morrow," laughed Roque.

"It will be because something breaks if we don't hit the high mark," assured Billy.

"Go over and size up your winged steed," directed Roque, pointing to a hangar across the field. "Show them No. 3"—this to one of the attendants.

"This is no mosquito," announced Billy, after a view of the fine lines of "No. 3."

"Speed there, I tell you, old boy," was Henri's comment as he walked around the rigging, "and carrying armor, too."

In an hour the boys had fully comprehended all the new features of this up-to-the-minute machine. They had been builders themselves and knew a good stroke of the business when they saw it.

Returning across the field, Billy and Henri were introduced to the rival aviators by Roque. The German airmen were a jolly pair, and showed by the professional courtesy they exhibited to the two of their kind that the coming contest was wholly a friendly one, and the results to be of value to the flying corps.

"No. 2 is a little older than your machine," was the greeting of one of the Teuton experts, "but it can hold its own."

Roque, speaking for his champions, gaily disposed of this claim:

"Keep your eyes open to-morrow, Fritz, or you will get lost somewhere in the rear."

"No fear, sir; there are no cobwebs on No. 2."

"What are they talking about, Buddy?" asked Billy.

"They just think they are going to beat us, that's all," interpreted Henri.

A bright clear morning presented itself for the aërial race, and Lake Constance lay like a broad mirror under the sunlight. The course was set due north and straightaway for twenty miles, and the turn fixed at a high point called Round Top, upon which, Roque informed the boys, a tall flagstaff had been mounted.

There were no preliminary trials, for both machines had been carefully groomed, and each was as fit as a fiddle.

With the aviators up the biplanes scudded down the field for the rise, and got away upon almost equal terms, the German drivers slightly in the lead, through better acquaintance with the lay of the ground. They trailed a yellow streamer, while the boys floated a band of black.

The ascent reached 2,000 feet, when the machines darted north like arrows. Roque and a group of officers about him followed the speeders through field glasses.

"They would run a swallow to death," remarked the secret agent to the aviation lieutenant at his side.

The aëroplanes had dwindled in the vision to mere specks, and there was no telling which was in the fore.

"Ah, they are headed back!" cried Roque. "Now for the show-down."

The glasses revealed the specks moving twin-like, and such was the terrific onrush that the crowd surging in the field soon caught a view of the contestants in growing size.

One enthusiast shouted: "Fritz will shut them out!"

But the glasses did not uphold the prediction. The machine with the black streamer was evidently using the reserve power that had been claimed for the newer make, and Henri was getting the best out of it. Yet the first-born craft was being handled in a masterly manner, had plenty of go to spare, and five miles still rolled between the speeders and the finish flag.

Now four, and the machines were bow and bow; now three, and the yellow band flapped a few feet behind the black; now two, now within the mile, and the whirring of the motors audible to the nerve-strained watchers below—then the close finish—and the white-faced pilot crowned victor was Billy Barry of Bangor, U. S. A.!

When the aëroplanes made landing, Roque pushed through the crowd and favored the Aëroplane Scouts with a forcible slap between the shoulders.

The victors were quick enough to extend hands to the vanquished.

"My friend," cried Billy, giving Fritz a warm grip, "it was only fifty feet, and it was the new motors that did it."

Then the crowd cheered, while the efficiency committee agreed with Roque that "No. 3" was the machine to be many times duplicated.

"That was something over a mile a minute coming back, I guess," figured Billy.

"The fastest heavy craft I ever sailed in," was Henri's expressed belief.

"I think you youngsters could make a living here if I were to bounce you," said Roque, who had been talking to some of the factory chiefs. "But you are hooked to my train for a while yet. And that reminds me that the mentioned train starts in the direction of Austria in the next two hours. Vienna is not a slow place, you will find."

As Roque was likely to jump anywhere at the drop of a hat, the boys in his company had long since lost the emotion of surprise.

Perpetual motion had become a habit with them.

In the Austrian capital the travelers encountered many invalids from the front, men who limped a little, had an arm in a sling, or a bandaged head. The Viennese on the surface did not seem to be greatly impressed by the tragedy of the war—evidently becoming used to it—yet the determination to fight to the finish, while not as grim as in Berlin, was there, nevertheless.

Another thing that impressed the boys was that here foreign terms were still much in evidence—French and English. In Berlin it was different.

As Billy said, "we're in a better mixing town." He and Henri were told that quite a number of medical and art students from America had decided that Vienna was safe enough for them, but Roque kept his airmen close under his wing, and they had no opportunity to pass even the time of day with any of the U. S. A. crowd.

They had no present desire, however, to attempt a bolt from Roque and did not believe, anyway, that their detention was just then seriously affecting their health.

"Time enough to run," was Billy's philosophy, "when his nobs begins to kick in our ribs."

They were seeing plenty to keep them interested, the arrival of sleeping-car trains bringing the wounded to the capital, the movement of troops bound for the Polish or Galician front, the daily sights of the Ring and the Kartnerstrasse.

Roque, as usual, was up to his eyes in war business, ever behind the scenes but ever moving, for there is close military coöperation between Germany and Austria-Hungary. All interests related to the war have been pooled—one empire gives to the other what can be spared. The king-pin of secret agents from Berlin served a purpose wherever he went.

He sat in no open councils, but privately conducted many of his own, was constantly receiving and dispatching messages, and the devices he originated to aid his disguised subordinates burrowing for information in hostile territory were too numerous for detail. These latter operations were not accompanied by band music, for officially this live wire had no identity.

"If that man took a pot shot at the ocean you would never know in what direction he was aiming unless you happened to see the splash." Billy was not far from being right in the summing up of Roque's methods.

Within the next hour the boys "happened to see the splash."

A uniformed messenger handed Roque a telegram. The secret agent hastily read it, and sprang to his feet, his eyes aglow with triumphant satisfaction.

"I've got Mr. Ardelle in a stone box at last!"

CHAPTER VII.
THE RAIN OF BOMBS.

The boys in silence watched the secret agent as he further displayed his gratification over the news conveyed in the telegram by snapping his fingers and slapping his knees, completing the performance by vigorous puffing of a big black cigar, of which brand he always carried a plentiful supply.

Billy and Henri were just aching to learn more about the reported capture of Anglin (Ardelle), just where the "stone box" that held him was located, and how the "smiling sleuth" had happened to run into a net that he could not break through.

But they were well aware that it would not be a bit of use to seek the eagerly desired information in advance of Roque's disposition to give it, and they did not dare openly to show personal interest in the matter.

It was not until the master plotter had burned his cigar to inch measure that he thought to address the lads, fixing expectant gaze upon him.

"They jugged the fox in Alsace, on the way to his home den, and filled up, I suppose, with some choice morsels to regale the enemy."

"Maybe it's another case of 'now you see him and now you don't.'" It was Henri who plucked up courage to say this.

"Not this time," insisted Roque. "He is tightly in the toils, and never a chance to show his cunning. His course is run."

It soon became evident that the speaker proposed to be "in at the death," as fox chasers call the finish.

In less than two hours Vienna, the city gay and unafraid, was behind the three travelers, and their next goal the imperial territory of Alsace-Lorraine.

Into Lower-Alsace, on the last leg of the journey, Roque and the boys took to horse, with cavalry escort. They were again on real fighting ground.

Henri picked out of a conversation between Roque and the captain of the troop the words "Homberg castle," later that a group of important German officers resided there, and still later that within those walls Anglin was a prisoner.

Billy was immediately posted by his chum as to the situation.

Upon arrival at the castle, Roque, in that mysterious but effective way of his, established his footing as a privileged guest, and his first move was to pass the guard at the door of the strong-room, where his chief rival in the art peculiar was confined.

The boys without reprimand were close at the heels of the German agent.

Anglin was sitting on a bench, under the checkered light of a high, barred window. While his face showed harsh lines of great strain, the inevitable smile was in his eyes. He arose instantly from the bench, and bowed gracefully to the foe who confronted him.

"Monsieur, you are welcome." This to Roque. Upon the boys he bestowed not the slightest recognition.

Roque, not to be outgeneraled as a diplomat, inclined his head in return.

"I came a long way to visit you, sir," he politely stated, "and would have regretted had you felt otherwise than you have intimated."

This fencing with buttons on the foils was soon succeeded by the sharp points unprotected.

"Ardelle, the longer the breath is in you the more you can tell; is the breath worth the telling?"

"You speak in riddles, Monsieur," quietly replied the prisoner.

"Do you deny that you are Ardelle?" demanded Roque.

"Am I now on trial?" was the counter-question.

Roque extended a menacing finger. "Have a care, man!" he thundered.

The prisoner calmly ignored the growing wrath of his arch-enemy, shrugged his shoulders, and with a wave of the hand indicated that continued argument was useless.

"You will have until to-morrow morning to decide whether you will accept me as an advocate or an accuser."

The Frenchman turned wearily toward the window, and with his hands folded behind him stood watching through the bars the little gray cloudlets pushing their way through the blue expanse of the sky. It might be that this view would not concern him after the morrow. He was thus engaged when Roque stamped his way out of the room. Henri would have paused in the hope of one look from Anglin but the latter seemed wholly unconscious of the presence of the lads.

Under the steely exterior of Roque, the milk of human kindness had not wholly curdled, for he sadly said, half to himself and half to his boy companions:

"He must expect no more than I could expect; when we fail we fail alone, and so alone must we suffer."

It was about two o'clock in the morning of the day when Anglin, or Ardelle, was expected to read his fate in the eyes of those assembled as a military tribunal. The identity of the prisoner was, no doubt, fully established, for the boys had noted the presence in the assembly hall earlier in the night of the sandy-topped man who had started the hue and cry in the Bremen hotel, where the French sleuth was posing as a public singer.

Billy and Henri were tossing in uneasy slumber. The only sounds inside the castle were occasional snores from adjoining apartments and from the outside the whinnying and stamping of the cavalry horses.

Suddenly the quiet was shattered as if by a thunderbolt. The boys literally tumbled out of bed, gasping from the shock. A blinding flash at the windows and another crash.

Soul-shaking cries of "fire!" resounded throughout the building, and through the halls swept volumes of smoke.

The celebrated ancient furniture in the castle, it having been the summer residence of French nobility, was fine food for flames, and the red destroyer soon raged in conflagration.

Crash after crash, and with each concussion myriad sparks shot through great holes in the castle roof.

Bombs were being dropped from aloft.

The boys hastened with other occupants of the upper floors to the broad staircase in front of the structure. There they paused, elbowed against the wall by those pressing from the rear. There was no wild confusion or panic behind them, however, such as might have ensued under the same terrifying circumstances with other than trained soldiers involved. When Billy and Henri took to the wall at the head of the staircase it was a voluntary act on their part. The same thought with both had impelled the pause:

Had Anglin been released from the fiery vortex or still restrained by iron bolts and bars?

The room in which the captive was held faced a gallery running at right angles from the main stairway.

Pulling their jackets up and over their heads, the boys plunged through the wall of smoke on mission of rescue—a mission without result, for the door of the place of confinement was wide open, and no one was there.

The rescuing party of two then turned their intent upon themselves, and none too quickly, for they had hardly won safety when the castle enclosure was wholly enveloped by consuming flame.

Farm buildings adjoining were also ablaze, and the wide highway stretching away to the east showed whitely in the glare.

In the red canopy overhead winged shadows whirred and whirled, dipped and leaped.

Billy and Henri proceeded down the road to escape the growing heat and rolling smoke. When the roaring of the fire had somewhat lessened in their hearing, they detected a familiar hum, just ahead and closing down beyond the border of the rising mist of the morning.

As aviators, the boys were instantly aware that an aëroplane was working near and the proof was immediately furnished by the appearance of the aircraft itself, swooping into the circle of illumination, skimming close to the surface of the highway.

The lads sprang forward to greet the aërial visitor, and as they did so a tall figure, hatless and coatless, leaped from the cover of a ditch nearby, ran like a deer alongside the skimming biplane, and vaulted into the frame behind the daring navigator.

As the machine took the uplift, Billy and Henri were so close, and the fire-flow so vivid, that they plainly saw the faces of both the saver and the saved.

The man who had jumped into the machine was Anglin; the aviator was Gilbert Le Fane, the noted airman of Rouen, whom our boys had once followed in flight from Havre to Paris.

From the fire zone there was coming a hurrying body of men, and rifles began to spit lead at the swiftly rising aircraft. Too late, though, to reach the height attained by the biplane. A shrill yell of defiance floated back on the breeze of the morning, and deep and heavy were the expressions of baffled rage by those grouped in the road below.

Roque and the sandy-haired assistant could be heard above all the rest.

The boys were again in the rôle of innocent bystanders.

When the sun later replaced the flames in lighting up the sky, not a trace of the French airmen could be sighted, save the marks of their raid—the blackened ruin of the castle and smouldering remains of the adjoining buildings.

Investigation instituted by Roque related solely to the escape of the prisoner. To put a quietus on his rival had drawn him from afar, and here again the elusive Frenchman had been jerked out of his clutches, this time into the very sky.

With the fall of the first bomb the single night guard over the captive had drawn the bolts that he might be ready to quit his post upon first order with the Frenchman in close custody. The second bomb so stunned the guard that he knew no more until regaining consciousness in the rear courtyard outside. He could only account for his presence there by the belief that the man over whom he had held watch had picked him up and carried him out of danger. There was a back way that could be traveled, smoke hidden, without observation.

"But how about the aëroplanes dipping just at the right time and place to carry him off?"

This was the point that especially puzzled Roque.

A farmer boy, listening, open-mouthed, to the questioning, offered a solution.

"You see, Monsieur," he bashfully explained, "it was a ghostly noise that was making between the big noises, like the wind blowing through the neck of a bottle stuck in a knot hole. I heard it in the road, a long way."

It occurred to the boys that this distress signal must have been given before they got away from the roar of the fire, or while they were probing the smoke in the gallery to reach Anglin.

"They were flying mighty close down and could probably hear a howl like that, if they were listening for it and knew what it meant." This opinion was advanced by Billy.

"I don't much believe they could hear a call from the ground, unless it came from the business end of a gun." Henri was the doubter.

"It is no use to argue," said Roque. "The fact remains that the air fellow had his bearings, and he got the lead from somewhere. I am not giving him credit for being a mind reader."

"That reminds me, Mr. Roque," remarked Billy, "that we might test this bearing business by a little air trip somewhere and soon."

"I have just such a thing in thought," grimly advised Roque, "and I will warrant that you will hear a few ground sounds before the quitting minute. We are going to take a down look at Belfort."

Now Belfort is a French fortress, where the soldiers in red and blue had been finding security every time they were rolled back from the plains of upper Alsace.

A tremendous amount of gunpowder had been burned on the flat ground in front of this stronghold, and our boys were in for a smell of it—something that would recall perilous travel with Colonel Bainbridge and Sergeant Scott in previous campaigns.

A wire to Friedrichshaven had started on the way the makes of biplanes that Billy called "Roque's best bet" since the day of the famous race over Lake Constance.

"Business will soon be looking up," joked Henri, when he heard of the order for the shipment of "No. 3's."

The presence of Ardelle in this region, extreme southwestern Germany, had raised suspicion in the mind of Roque that some special demonstration was brewing, and the lurid performance of the French airmen in blowing the roof from over his head served to further elevate the confirmed idea that trouble and the French agent always traveled together.

Roque was not here to mix in the actual military operations—that was not his business, but he was ever open-eyed on the trail of the boss gamester on the other side. He had expected this time to put his rival on the safe side of the ground, but spades did not prove to be trumps.

Somewhere in the gap of Belfort, as the valley south of the Vosges mountains is popularly known, Ardelle was, no doubt, preparing for another comeback, and Roque was scheming to meet him halfway.

There was no chance to get under the guns of the frowning fortress beyond the frontier, so the only way to size up the situation was to go over them.

Here was where flying experts jumped to the front.

CHAPTER VIII.
ALONG THE BATTLE LINE.

With the arrival of the biplanes from the factory, the Boy Aviators were kept busy with brief test flights over valley and plain, awaiting the convenience of Roque for the wider sweep he was planning. It developed that the boys were expected to navigate separately on this occasion, Billy to pilot Roque himself, and Henri to be accompanied by one Renos, who had been awarded a service badge of honor for his work as an aërial observer in giving first warning of the advance of a French division against Burnhaupt, which saved the day for the Germans.

"The seaplane is the rig for weight carrying," exclaimed Roque, in accounting for this assignment, "but these machines, as you know, are solely in the speed class, and it is many chances to one that we will be compelled to tax every ounce of power before we get through. So we have no use for deadwood."

Renos, who was to sit behind Henri, was the silent man of the expedition, as far as talking was concerned, but when it came to be up and doing he could be counted on to the limit. He was a human route-box of the Sundgau, the fighting territory, and very much at home in a flying machine. When the two machines one morning flew over the German frontier, in compliance with the "ready" order of Roque, Renos' knees were crossed by a wicked-looking rifle, and of the party he was the only one armed.

Billy, observing this war-like figure, asked Roque if he expected to get into close quarters on this trip.

"Not unless some of the bomb-throwing crowd that scarred the landscape the other night should cross our path," replied the secret agent.

As Renos was the qualified guide, the biplane bearing him went to the front, and Henri received overshoulder directions as to the course to be maintained.

The apparent reason why the German expert did not pilot the craft himself was that he wanted a loose hand in case of emergency, and a free eye for the panorama below. He was satisfied, too, that one as good as the best was doing the steering.

Henri was instructed to keep a respectful distance from the near mountain peaks, where the French had mounted artillery, for one round from these guns, close enough, would have ended the flight and the flyers there and then.

But Roque and Renos kept constant vigil with glasses, and Billy wondered that the pair did not get a crick in the neck with all the head-turning they did.

A sharp order advised the pilots to send the biplanes farther aloft, and circle. The French fortress of Belfort could be seen directly underneath.

The aviators well knew that an explosion close to an aëroplane is often sufficient, through the force of the air concussion alone, to bring it down, and they knew they could not chance a close shot from the long-range guns in the fort.

Though the machines now evoluted at greater height, the powerful glasses enabled the observers to plainly distinguish the movements below.

It was quickly manifested that the garrison lookout had become aware of the aërial visitation, and that they did not approve of the color of the hovering aircraft.

A couple of smokeballs ascended and burst in the center of a cloudrack far to the right of the machine. Renos broke his record for silence with a shrill cackle.

"Save your powder, you numbskulls," he shouted for his own satisfaction.

Roque seemed oblivious of the gunplay below. As the biplane described great circles over the fort, he kept his glasses steadily aimed at a point in the enclosure over which the flag was floating.

The men who emerged from the officers' quarters all wore the French uniform.

Roque had evidently cleared up a disturbing point in his mind as he muttered something about a "fool story," and "I might have known there was nothing to it."

Having satisfied himself that it was still an independent little war at this remote point from the main field of operations, and that he had been misled by some advices previously received, the chief observer passed the word to his pilot to back-track, at the same time giving signal to the companion biplane.

As the machines swung around for the return flight, and drew closer together, Renos gave a megaphone yell through a hollow formed by his hands:

"Speed for your lives, they're on the wing!"

Above the gentle slopes on the west, leading to the summit of the mountain ranges, aircraft had arisen, looking, at a distance, like black dragonflies.

At the same moment, the invading biplanes also had a reminder to hurry from the fortress they were leaving behind.

A shell burst seemingly quite close to the machine Henri was driving, and the craft dipped far to one side.

Billy's heart beat up to his throat when he saw the break in the flight.

But his was an exulting cry when the momentarily stricken flyer righted, and bored ahead.

"Glory be!" hoarsely rejoiced the boy from Bangor, when his chum again drew to the upper level.

Seventy miles an hour was the clip of the fleeing biplanes, and no less speedy the onrush of the aircraft from the slopes.

"Steady, and a little to the right," Renos instructed Henri.

The observer was resting the rifle barrel on the rigging, awaiting a broadside target.

Sping! One of the attacking aviators was first with his rifle, and the bullet nicked the armored side of the German craft. Sput! Henri heard an angry exclamation behind him, and shifted an eye long enough to see that Renos was nursing a bloody wrist on his knee.

"How hard are you hit?" was the anxious question of the young pilot.

"Nothing to kill," replied the observer, as he used his uninjured fingers and his teeth in knotting a handkerchief above the wound so as to compress the severed artery.

With the utmost calm he then deliberately used his left hand in rifle aiming, and sent a bullet into the nearest hostile machine.

Whether the shot crippled the pilot of the leading pursuer, or whether it was the menace of the heavy howitzers on the German frontier, which was now of short approach—the French flyers suddenly ceased to be aggressive, and with a parting salute of rifle practice, turned back toward their mountain station, while the German machines dashed across the line of safety.

Upon landing Billy indulged in a sort of war dance around his chum.

"Thought you were gone that time, sure, Buddy," he cried, "and it was simply great the way you pulled out of the hole."

"I guess I was stunned for a minute, as though somebody had hit me with a hammer," explained Henri, "but when I found the controls were still working, it was a bracer, I tell you. And if there isn't a cool head" (nodding toward Renos, who was inspecting his wounded wrist) "I never saw one. He stretched his arms over me ready to take hold if I failed to rally, and did it as a matter of course. Not a tremble about him, either."

"What do you think of the No. 3's now, boys?" queried Roque, when he had dispatched Renos in search of a surgeon.

"They're dandies, all right," promptly agreed the happy pilots.

"They will do to hunt trouble with, anyhow," laughed the secret agent, who was immensely pleased with the flying achievements of the day.

Roque, pluming himself with the idea that, though he did not hold Ardelle when he had that artful dodger under his thumb, he had at least chased his rival out of the empire; and, having also eased his mind as to the report of a new element in the Alsace campaign, he was impatient in his preparation for departure. Master of detail though he was, the big moves only appealed to him.

A great battle was raging at Soissons, on the Aisne river, in France, and Roque had in mind an aërial journey north, and quick flight across the border to the scene of the fierce artillery duel, following the line of march of the mighty force under General von Kluck.

The crippled Renos was replaced in the observer's perch by an aviator known as Schneider, a very daredevil, and who was at first inclined to doubt that the boy with whom he was paired had sufficient skill and courage to pilot a military biplane in an active war zone. Henri very quickly convinced the doubter that he was very much older than he looked when it came to the fine points of aëroplaning, and, too, that when there was an emergency demand for "sand" the youngster had plenty to spare. Schneider had additional assurance of capacity when he was advised that both of the lads carried Roque's indorsement of efficiency.

It was a bitter struggle that the Aëroplane Scouts were to witness at Soissons, and six days of it had already passed. The earth was still dropping on many graves of the German fallen, and yet, sprawling in attitudes along the heights, in the deep-cut gorges of the plateau, and across the flat valley bed were French infantrymen in their far-to-be-seen red-and-blue uniforms, swarthy-faced Turcos, colonials, Alpine riflemen, and bearded territorials.

At staff headquarters, in the first officer that passed near them the boys recognized a familiar figure, no other than Colonel Muller, whom they had first met in far-away Texas, U. S. A., on the day of the record flight, and again in the hangar camp at Hamburg.

Billy impulsively stepped forward. "How do you do, Colonel?"

The officer instantly turned in his stride to inspect the speaker. "Hello, Boy Aviator," was his hearty greeting. "How under the sun did you ever get here?"

"Same old way," said Billy, "the airline, of course."

"And here's the other one," the colonel reaching for Henri's shoulder.

"By the way," continued the big soldier, "this must be a field day for flyers. Here, Hume, come and see what the wind brought in."

The officer addressed moved at quickstep in response to this invitation. It was the aviation lieutenant from Hamburg. He grinned from ear to ear when he laid eyes on his former charges.

"Can't lose you if I try," he exclaimed. "Have you enlisted with us?"

"No," laughed Billy, "we're still driving cars for the good merchant from your town," with the backward point of the thumb at Roque, who was engaged in close confab with a group of staff members near by.

"Did you blow in with Schneider, too?" asked the lieutenant. "I just want to say that you will bore a hole in a stone wall sometime if you train with that fellow. Nature didn't give him red hair without reason."

"Now that you are here," broke in the colonel, "you must not be allowed to get out of practice. I expect that one of you will have to give me a ride along the front before long. I have lost three horses this week."

"We'll do our best to oblige you, colonel," volunteered Billy.

It was no merry jest, that ride Billy gave the colonel!

At the time, the French retained a foothold north of the river at only one point—St. Paul—where the bridge from Soissons crosses, and this by a perilous margin, since the bridgehead was completely commanded by German artillery on the heights.

The battlefield entire covered a front of about seven miles, the center and eastern flank a high, level plateau rising steeply a couple of hundred feet from the valley of the Aisne. On the western side a deep valley ran northward, bounded on either side by turnpikes. An airman taking the big curve of the river would not be considered a good risk for a well-regulated insurance company.

But it could be done—and Billy Barry furnished the proof.

When the next day broke a bloody conflict was raging between the two turnpikes, the French infantry attack on German trenches preceded by a terrible artillery bombardment, a storm of shell and shrapnel.

Colonel Muller beckoned Billy to his side. They stood together on the heights from which the French had been expelled only the day before.

"My boy," was the brisk address of the officer, making a field-glass survey of the smoke-crowned landscape, "I am going down the line, and I am to do the distance in an aëroplane. Is it you or Schneider who will do the driving?"

"You gave me the first call yesterday," reminded Billy.

"That was my intent, and it still holds. I was only seeking to learn if you were of the same mind since that powder mill let loose down there."

"I well know the odor of it," stoutly maintained Billy, "and it doesn't weaken my knees."

The young aviator, accepting the matter as settled, hastened toward staff headquarters. "Mr. Roque," he excitedly called, "Colonel Muller wants to try one of the No. 3's this morning, and I'm to pilot."

The secret agent lifted his eyebrows as though surprised, but he really was not. The arrangement had already been made.

"Say, Buddy, this is rough that we can't both go; and suppose something should happen to you?" Henri had just realized that something was up, in which his chum was vitally concerned.

"Don't you worry, pard," consoled Billy, "it is only a little spin of a few miles, and we'll be back in no time."

"Wish it was me," sighed Schneider, for this firebrand guessed that it would be a red-hot journey.

As the biplane swept into the breeze current, trending to the river, which then was running brimful, and in many places overflowing its banks between the two armies, Colonel Muller advised Billy to keep the machine climbing for the time being, as a terrific fusillade was in progress in the distance of the next two miles, the shells hurtling through the air like lighted express trains. In the three steep-sided ravines that deeply notched the plateau on the east French troopers swarmed like bees, and at this cover the big German guns were blindly banging.

"We can't see much, Colonel, at two thousand feet," complained Billy.

"You would see nothing at all if we ran into one of those fragments of shells," coolly suggested the officer, "but never mind, you will do some diving in a few minutes."

Billy got the signal to dip at the juncture of the turnpikes, and to hold a level and lower course along the line of battle, marked here by infantry fighting between the seemingly crawling columns far below.

"Down!"

The colonel's order was peremptory, and Billy forthwith volplaned toward the earth.

CHAPTER IX.
THE LUMINOUS KITE.

The biplane had hardly scudded its length on the turnpike, when the colonel leaped from the machine, his sudden appearance greeted by salvos, both of cheers and an extra round of rifle discharge.

Billy sat like a statue in the machine, facing a reserve force of grim, gray-garbed veterans standing at attention.

The front rank soldiers eyed the boy curiously, no doubt wondering that one of his years should be serving in the capacity of a full-fledged military aviator on a mission so supremely perilous.

Billy could not understand what Colonel Muller was saying to the commanding officer of this regiment, but he could see the effects rippling through the serried lines, a stiffening of attitude, a closer grip of rifle stock and squaring of shoulders.

The column, solid and compact, the German practice of close formation, moved with clockwork precision down the field to back the general charge against the living wall that barred the way.

"Charge! Charge!" The cry from a thousand throats.

The forces mixed in a struggling, swaying mass, with indescribable noises, the clashing of steel and the squealing of horses, for cavalry had joined the fray.

Billy jumped out of the machine into the dusty road, the sole spectator there of the conflict that raged but a half mile distant.

Colonel Muller had taken to horse and was riding furiously to rally incoming reinforcements for the gray column.

A rattle cut into the sound ruck—the machine guns of the Germans had turned loose, and men were mowed down like ripened corn.

But fainter now in Billy's ears grew the roar of violent contention, alternate advance and retreat serving to shift the tide of battle further northward, and finally stemmed by the final demonstration of the day at Soissons bridge.

Barring the occasional wild gallop of a riderless horse down the road, the young aviator saw no signs of life about him, and he was too far away to hear the groans of the wounded on the sodden field now enfolded by the gathering gloom of evening.

"I wonder if the colonel has forgotten that his carriage is waiting," thought Billy, trying a bit of mental cheer to relieve the strain of his trying position.

The colonel, however, had not lost his memory along with his hat, for even then a foam-flecked horse was bringing him back to the driver of his aërial chariot. Mud-bespattered from head to foot, he sent a hearty hail ahead of the pounding hoofs of his weary mount.

"Ahoy, my stranded mariner: is supper ready?"

That reminded Billy of a decided vacancy under his belt, but the glad sight of the colonel was the best tonic for a drooping spirit.

"We will wheel this airship out of the way for a spell and have a bite to eat in the trenches."

Concealing the biplane behind a clump of bushes the colonel gave Billy a hand-up, and the horse cantered away with its double burden in the direction of the slopes.

It was about 7:30 when the colonel and Billy climbed over the slippery slopes to the line of reserve trenches, lowered themselves into one of these holes in the ground, and it was evident that the occupants knew how to convert a ditch into a home.

This trench had a head cover formed of cross-beams, overlaid with branches and earth—a sure protection against shrapnel. There was a long bench of telegraph poles, little cupboards for cartridges and kit, and ramps for reclining chairs or couches, and drains to carry off the rain.

"Come into our parlor, colonel," invited one of the soldiers, leading the way into a subterranean chamber, which was warmed by a fire in an old perforated petroleum tin.

"It is wonderful what ingenuity and labor can accomplish out of the most unpromising material," observed the colonel.

"Made in Germany, colonel," laughed one of the veterans, "no matter where you put them."

From the business end of the trench a hot meal was speedily produced for the visitors, adding another touch of surprise for Billy.

"Well, my lad, we must report to the general," announced the colonel, who had politely denied the petition of the trench veterans that he try one of their couches for the night.

"You don't mind an air trip in the dark, do you?" inquired the colonel.

"Not a bit," assured Billy, "I've made many a one."

It was quite pitch black when the colonel and Billy rode back across the plain, but the horse was sure-footed, and the way was fitfully lighted by the occasional upshoot of rockets that left a long green stream of stars, revealing the now silent battlefield and its dreadful record of uncounted dead.

While Billy flourished an electric torch in giving the biplane a careful look over, the colonel bestowed a playful slap on the flank of the faithful horse, which sent the animal trotting up the road.

"He knows his number and troop as well as I do, and will go as straight as a die to the feed trough," asserted the colonel.

"Are you ready, boy?"

"Trim as a ship, colonel."

With a flare on the compass, rising high, Billy held the nose of the biplane in the direction of the heights that centered headquarters.

Small red sparks glowed in the trenches below, and the upper darkness was ever and anon split by signal rockets and leaping flames of light from countless campfires.

Billy, with the aid of the small searchlight in the bow of the biplane, found safe landing, also insuring a sight of the colors to the sentries, who might otherwise be tempted to take a pot shot at the winged, midnight visitor.

Henri was the first to hear the whirr of the incoming aircraft, for which he had for hours held an open ear.

"Here you are at last!" he exclaimed, making an open-arm break for his flying partner. "You haven't lost an eye, or a leg, or anything, have you?" he anxiously inquired.

"Sound as an Uncle Sam dollar, old boy," assured Billy. "But you just bet I'm sleepy."

"I believe even Roque was uneasy about you," said Henri, as he insisted on giving Billy's blanket a snug tug.

That the secret agent proposed to reserve the services of the young aviators to himself thereafter and during their stay in this locality was made manifest when he told them the next day to make ready for a quick departure in the biplanes. As usual, he furnished no advance particulars.

It appeared that Schneider was also to figure in the expedition in a capacity indicated by his employment of oiling and polishing a service rifle of the 16-shot brand, and the display of a pair of long-barreled revolvers stuck in his belt.

"He looks like an arsenal on parade," commented Billy when the red-haired flyer, in war-like array, passed on the way to conference with Roque.

"There is no peaceful intent about that get-up," admitted Henri. "And let me make another prediction," he continued, still proud of his last previous success as a prophet, "this isn't going to be any pink tea or garden party to which we're going."

"What a head you have," said Billy, beaming with mock admiration.

There was a decided lull in the fighting this day—the ninth since the continuous combat had been commenced, as the soldiers of the two armies were apparently resting on their arms. Some fresh planning, no doubt, was in progress.

The boys wandered around the camp, restlessly anticipating the expected summons from Roque. The latter, however, had not picked daylight in which to operate, for it was long past nightfall when Schneider sought and advised the boys that the starting time had arrived.

The moon was working full time when the biplanes set their course, following the turnpike toward La Fere.

Above a farm, which had practically been razed, and on the edge of a ruined district, both Roque and Schneider signaled the pilots to lower the flight, and the biplanes circled groundward, landing near a row of stunted willow trees. They showed no lights, and with the motors silenced lay hidden behind a huge pile of debris, close to a wrecked dwelling, so close that the full moon shining through the shattered roof gave the aviators a dim vision of hopeless confusion, cooking pots and children's toys, broken clocks and tables, knives, forks and books strewn on the floor, beds and everything awry.

Billy and Henri had as yet no inkling of the purpose of this mysterious proceeding in which they were engaged. Their companions did not seem to be in a hurry, either, to enlighten them. Roque and Schneider appeared intent in upward gaze, perhaps hoping that the moon and a dense bank of clouds forming near would soon come together. As a matter of fact, a total eclipse of the great orb above did follow, with the effect of the sudden blowing out of the one lamp in an otherwise dark room.

Curious to relate, it was not long until the moon was replaced in the now black canopy by a small but quite silvery brilliant imitation of the big illuminant.

The diamond-shaped light in the lowering sky flashed this way and that, as if responding to the manipulation of an aërial cable.

Roque was not puzzling about the appearance of the dancing light; it was the message that it conveyed which baffled him, sent, as it were, from within the German lines, and, maybe, of vital concern—aid and comfort to the enemy.

Sentries on the heights had reported night after night of this queer, intermittent flashing in this very place, and when Roque heard of it, he instantly comprehended the meaning.

Some spy within the lines was using a luminous kite to signal information of value to the foe.

This is what had brought the secret agent, an adept in the same kind of game, flying through the night to scotch the play and the player.

Roque and Schneider skirted the ruins, and stumbled over the plowed ground with all the haste that such rough going permitted. The boys, free of any order to stay where they were, cautiously brought the rear. They were mighty curious to see what was going to happen.

Schneider had taken the electric torch from under the pilot's seat in one of the biplanes, and it had occurred to Billy to follow suit. This precaution served to save the party an ugly tumble or two into forbidding ditches.

The still-hunters had just emerged into a road with a wonderful avenue of trees. The kite telegrapher's hidden nest was near at hand. The position of the kite itself indicated that.

A streak of moonlight breaking through a cloud-rift revealed Roque and Schneider kneeling in the road, and there was a glint of a leveled rifle barrel.

The boys backed up against a tree, expecting momentarily to hear the whip-like crack of the gun. But instead came the bark of a dog—one shrill yelp, then silence again.

The luminous kite, unleashed, followed the moon into the clouds. Roque and Schneider dashed forward, but for nothing else than to use the electric torch in locating a half-loaf of bread, some cheese crumbs and a ball of cord.

The sentry dog had saved its master!

"Nothing to be gained in chasing that fox to-night," growled Roque. "He's deep in the brush before this."

"I'd like to have got a pop at the dog, at least," complained Schneider, patting the stock of his rifle.

The boys having no desire to be the victims of any mistake of identity, marched forward, Billy waving the electric torch, and calling to Roque:

"It's us."

The passwords were unnecessary, for Roque knew all the time the boys were trailing him, but was restrained from objecting by fear of some word reaching the ear of the man they were stalking.

"You gadabouts," he admonished, "you should have been guarding the biplanes instead of prowling around in the dark like this."

The tone of the reprimand, however, was not one of great severity. The boys had disobeyed no order, for none had been given.

"As soon as day breaks," said Roque, as they plodded wearily down the road, "we will continue the hunt in the machines, though I doubt very much whether it will amount to more than a waste of time."

"If I see a man with a dog underneath us, just bring me within rifle shot, young man, and I will show you something fancy in the way of gunning."

Henri, whom Schneider was addressing, mentally resolved that he would be in no haste to perform as suggested.

Conditions, however, were reversed long before this test could be made. Indeed, the reversal, with the dawn, was at hand. The hunters were the hunted.

The thud of iron-shod hoofs, the clank of sabers—a troop of cavalry charging through the wooded avenue—four madly racing footmen in the furrowed field.

Full two hundred yards between them and the biplanes!

CHAPTER X.
THE CARRIER PIGEONS.

Billy and Henri, with much less weight to carry than their stalwart fellow fugitives, and much spryer as sprinters, easily led in the race to the flying machines.

Schneider stopped more than once in his tracks to fire from the hip at the pursuing cavalrymen, but he failed to score a hit until the leader of the troopers had almost ridden him down. One of the long-barreled revolvers emptied the saddle of the rearing charger. Schneider had thrown his rifle away at the last moment, finding his pistol more effective in close quarters.

By this time, the boys, assisted by Roque, who was doing some shooting himself, until all of the cartridges in the revolvers he carried were exploded, had pushed and dragged the biplanes into the road, and ready for the getaway.

Schneider, with a yell, hurled the empty revolvers in the direction of the next comer, then bounded across the first ditch in his way, jammed a shoulder against the now humming machine in which Henri was seated, to give it starting impetus, and at the same instant leaped within the machine.

Both machines were off in a jiffy, and when the cavalrymen in force galloped to the spot, their carbines fell short of range. That they had been chasing airmen was something of a surprise for if they had not been so sure of a capture, the troopers would probably have pumped lead much earlier in the chase.

"Guess he didn't get his man for keeps," remarked Billy to Roque, as a side turn of the aircraft enabled him to look down on the field, where a dismounted rider was getting a helping hand up from a comrade.

"Schneider gave him something to remember, anyhow," grimly replied Roque.

In the other machine the red-topped and red-tempered aviator in the observer's seat was deeply deploring, in no uncertain terms, the loss of a crack-a-jack rifle and two up-to-date revolvers, borrowed for the occasion.

"Hume may toss earth when I tell him his pet irons are gone, but it was a shindy for quick action, and no saving grace."

Schneider evidently intended to tell the aviation lieutenant about the fight before he mentioned the missing weapons.

The next flight planned by Roque was one of long distance—starting twenty-four hours later, and leaving France.

"Good-bye, my young friends, and good luck to you; if you ever see Colonel McCready again tell him 'here's looking at him.'"

These were the parting words of Colonel Muller, accompanied by a warm hand-grip.

When the flying party finally reached Strassburg, the big German city of the Alsace-Lorraine region, it was a glad day of halting.

They had floated in over a country literally shot to pieces by the concentrated fire of the French and German guns—that is, in French Lorraine—and in the distance viewed the great fortress of Metz. To the aviators it appeared as though the land hereabouts had been devastated by a gigantic earthquake, which had shaken down all the towns and villages into a mass of shapeless, smoke-blackened ruins.

The boys wondered that they did not see more soldiers in the open, and Henri expressed this wonder to his companion in the biplane.

"Oh, but the woods are full of them," assured Schneider, pointing to the small columns of smoke rising here and there from the snow-clad forests.

True it was that these same woods contained thousands and thousands of armed warriors, ever on the lookout, who were gazing across the frontier at the other woods, which concealed countless thousands of soldiers of the Kaiser.

In Strassburg, Roque was again in touch with the invisible strands of the far-spreading web he maintained. Among his first advices was the most disturbing one that Ardelle had returned and had been making some ten-strikes within the borders of the empire.

The boys shrewdly guessed that something of the sort had happened from the renewal of the German agent's habit of charging almost every sort of disaster to the secret work of his French rival.

Roque realized, as one of the profession, what an important factor is the under-cover man who works within the enemy's lines in the service of his country. And with a keen blade like Ardelle, big things were possible, as past performances indicated.

But even Henri, as a self-claimed prophet, had no idea that the man he knew as Anglin would bob up in Strassburg, though the city was as likely a point as any in the war zone for secret service activity.

When Billy jokingly asked his chum if he had any predictions to fit this occasion, Henri admitted that his second-sight "was off the job."

It soon developed that the secret service experts of both sides were matching wits in this quarter. Reported in Roque's calendar of the week was the giving away by one of his workers in hostile territory of a French attack on the Germans during a fog, with the result that the intended surprise resulted in a rout, and the assailing force mowed down almost to a man. The mute testimony was in a low-lying valley out in the Lorraine field—700 graves in a space 200 yards wide and about 50 broad.

Then a counter-move, wherein the French had advices from some source unknown of the coming flight of a Zeppelin out of the Black Forest, and three French aëroplanes were ready to charge at the big dirigible, which, after a continuous exchange of fire lasting forty minutes, made narrow escape to the north, just when the lighter craft had succeeded in getting above it for a finishing stroke.

As it came about, and in a queer way, too, the boys were the first to blunder upon a cunning ruse being resorted to by a smooth worker in getting away information under the very nose of the astute Roque.

Billy and Henri, indulging their liking for high places, and having a little leisure to look around, found a favorite perch in one of the famous towers of Strassburg. They were interested, as airmen, in watching the daily flying exhibit of the pigeons 'round about.

"Have you noticed, Henri, the streak of feathers every once in a while that don't stop to associate with this housekeeping bunch? I've seen two of these birds already this morning; they act just like an aëroplane, circle about, and then break away like a bullet. There's one now. Look!"

Henri followed the aim of Billy's finger, and, sure enough, a long-tailed flyer was cutting the air like greased lightning in a straight line west, without the slightest notice of the many of its kind pluming themselves on neighboring towers and housetops.

"They make long visits," commented Billy; "I've watched, but never see any of these air hustlers come back."

"That's funny," observed Henri, "let's borrow a glass this afternoon and find out, if we can, where they start from. Why, this is good sport; we'll be wearing badges next as pigeon detectives."

The boys had small notion then that they were butting into a real business proposition, but one that did not advertise!

They were just curious to find out from where came the busy birds that would not take time to visit with their brothers and sisters.

The most that the tower observers could discover, even with the field glasses, borrowed without leave from Roque's traveling outfit, was that the next bird comer took its bearings over a red-roofed building, rising out of a circle of tall trees, a full mile to the east.

Had it so happened that Roque was in a social mood, and the boys making him a confidant of their bird study diversion, there would, without doubt, have been no delay in striking at the heart of the problem—and everything else under that red roof.

Carrier pigeons were not beneath the notice of the big man with the delicate touch!

But Roque was not inclined at the time to indulge in fireside fancies. He was hooked up to a procession of events that needed constant attention, and as it was all ground work for the present, he had no use for aviators.

So he missed the first bang at the very musser-up of his plans whom he was, day and night, seeking to locate.

"We'll amble out that way to-morrow and learn how to break pigeons of the loafing habit."

Billy had once had a loft full of pouters in Bangor, that, he claimed, ate their breakfast in bed!

"We'll shake Schneider and start early."

Schneider had been detailed by Roque to keep an eye on the boys, but Henri felt sure that this firebrand would not be interested in pigeons, save in a potpie, so he suggested the "shaking" process.

Trained in the sense of location by their aviation experience, the boys proceeded without difficulty to the sparsely settled neighborhood of the red-roof, which they found to be in the center of a neglected garden, overgrown with weeds.

"Don't see any pigeon loft yet?"

Having been a fancier himself, Billy knew how the birds were housed.

"You might also say that you don't see any pigeons," added Henri. "We've surely run by the station."

"Not on a little excursion like this," maintained Billy. "This is no ghost story."

With the words he led the way up the long gravel walk extending from the rusty iron gate to the front of the house.

"What will we tell them?" he asked, reaching for the brass knocker on the dingy door of the dwelling.

"How will it do to say we are from the gas office?"

"A fool answer fits a fool's errand," agreed Billy as he gave the knocker a sounding rap.

The pounding awakened no sign of life.

"Come on, Billy," urged Henri, "let's go. It's all a crazy move, anyhow, and it was just because we were idle that we ever thought of it."

"I'm going to try the back door," insisted Billy, "and then we'll quit."

There they got a response, probably after an advance inspection. The door was partly opened by a bent, palsy-shaken old man, who in quavering, high-pitched voice inquired their business. The question was in French, and Henri responded:

"We just came out to look at your pigeons, and"—the age fell from the figure in the doorway in the twinkling of an eye, two long arms shot out, and in steely grip the astonished visitors were jerked inside, the door closing with a slam behind them.

"What's the matter with you?" gasped Billy, whose collar had been given a tight twist by quick-grasping, sinewy fingers.

Another violent wrench of the neck-joint was the rude form of answer. Billy's fighting blood took fire, and he launched a kick at his tormentor which sent the latter spinning, doubled-up, clear across the entrance hall.

The jarred one, recovering his breath, leaped like a panther at the Bangor boy, but Henri gave him the tripping foot, and he measured his length on the dusty floor.

The boys were making a break for the door, when a new figure blocked the way, suddenly emerging from a room nearby—a resolute fellow, with a cold, gray stare, backing up a steadily leveled revolver.

"Been stirring up the monkeys, have you, Fred?"

The fallen man raised himself on his elbow and made the air blue for a moment with his wrathful expressions.

"I'll fix you, you whelps," glaring at the sturdy youngsters who had bested him.

"Stow the threats, Fred," advised the cool-head, who had restored the pistol to his hip-pocket when he sized up the invaders as unarmed.

"What the devil brought you here?"

The newcomer put a snap in the question, but with no change of icy eye.

"What devil sent them here, you'd better ask?"

This suggestion from the battered Fred, who had again regained his feet.

"That will all come out under pressure," intimated the cool one. "As long as you chose to honor us with a visit," he added with quiet irony, "we must get properly acquainted. Show the young gentlemen into the parlor, Fred."

Billy would have started a debate there and then had he not been, as usual, stumped by the French language, which he only understood by fits and starts. He knew for sure, though, that he was in Queer Street, with this sudden shift from the regulation German talk he had been hearing since landing in the empire. It was up to Henri to set matters straight.

Henri, however, had come to the conclusion that the pigeon story was not popular here, considering its effect on the man who had first met them at the door. So he wore a thinking cap on the way to the "parlor."

This apartment was the only one that had a living look, all the others, noted in the passing, cheerless and empty. It was a "sky parlor," being reached by narrow stairway, only a garret between it and the roof.

An old table, rickety chairs, portable cots and a rusty oil stove were in evidence. There was a wide fireplace with no fire in it. It occurred to Henri that the present occupants of the house did not approve of smoking chimneys.

To get a line on what might be expected, he mildly inquired, with a pale smile:

"Now that we are here, for what are we here?"

He was certain that he himself could not win a prize with the correct answer.

The cold-eyed man could not restrain a short laugh in his throat.

"You are the fellow on the witness stand," he said, "but we must wait for the prosecuting attorney to help us along."

In the waiting time the boys could hear through an open trap-door above them the fluttering and cooing of a score or more slate-colored doves, and it had just dawned upon Billy that there was some particular use for the sheets of oiled tissue and skeins of pack-thread that littered the table.

CHAPTER XI.
UNDER THE RED ROOF.

There were no additions to the party in the "sky parlor" until after candlelight. The man called Fred was half-asleep on one of the cots, when suddenly aroused by repeated knocking below. He made stealthy descent, listened at the entrance for a moment, and apparently satisfied with the signal conveyed in the rapping outside, cautiously unbarred and opened the door. The person admitted did not come empty handed, for when he stepped from the stair-landing into the upper room he, and likewise Fred, were carrying market-baskets of goodly size.

"Hello, Gervais," was the hearty greeting he gave to the cool one, the latter engaged, with a well-thumbed deck of cards, in a game of solitaire.

"Hello yourself," returned the gamester, dropping the cards, and coming forward to relieve the newcomer of the market basket.

Billy and Henri were seated in the shadow, beyond the range of the candle rays, and at the time escaped notice. Both had started, however, at the first sound of the new voice.

From a side view the make-up was that of a typical huckster of these parts, fur cap, with ear lappets, corduroy greatcoat and cowhide boots. Between cap and collar bunched a heavy growth of iron-gray whiskers.

The boys did not realize that their instinctive move, occasioned by a certain tone in the voice, had not been amiss until the speaker had turned full face.

Even the luxuriant whiskers could not wholly hide the Anglin smile!

Much to the astonishment of Gervais and Fred, and infinitely more to the surprise of the imitation huckster, the boys at a single bound jointly invaded the circle of light and grasped the elbows of their one-time Calais acquaintance.

"What sort of a hold-up is this?" cried Anglin, in startled recognition; "is it raining harumscarum aviators in Strassburg? By the great horn spoon, it's enough to make me believe I've got 'em to see you under this roof."

"I'll bet you knew that we blew in with Roque," proposed Billy, "for you have a way of seeing seven ways for Sunday."

"You win, laddy-buck, on the first statement, but I'm still up a stump on the proposition of how you got into this house."

"We were loafing," put in Henri, "started out on a pigeon hunt and got the drag when we mentioned it at your back door."

"Pigeon hunt?" Anglin wore a puzzled look.

Henri made quick explanation of the whole affair.

"Ha! I see," exclaimed Anglin. "By the way, you did not happen to mention your tower observations to anyone else, did you?"

This last query had a dead-earnest ring, with a rising note of anxiety.

"Not on your life," assured Henri; "in the first place, the big chief had no time to bother with us; we had no inducement to talk to anybody else, and, all in all, who'd have cared about the bird business, anyhow?"

"Well, it seems there was one fellow who did."

Billy indicated Fred, who was unpacking the baskets.

"There are others," laughed Anglin, much relieved by the boys' statement. Fur cap, wig and false whiskers were tossed onto the mantelpiece, and the huckster was no more.

The baskets had produced a plentiful supply of ham, cold chicken, and the like, and not one of the party could be charged with lack of appetite.

In the glow of good-fellowship, Fred told Billy he was sorry that he had given him so rough a reception.

"Honors are easy, old top," was Billy's jovial acceptance of the apology, "and I am glad now that we did not break any of your ribs when we banged you around."

"Say, Mr. Anglin, I am afraid, after all, that we may bring down trouble on your head. I just know that Roque will be in a great stew when he finds we are gone and will fairly comb the town to locate us."

The idea had begun to trouble Henri to the extent of spoiling the pleasure of this reunion and indoor picnic.

"I have thought of this," admitted Anglin, "but the danger of discovery is ever the same, and I don't believe this will either hurry or lessen it. Besides, we are prepared, or, rather, had the way prepared for us, to make a run on the slightest warning."

This restored to Henri happier thoughts, though he still held belief that Anglin might have been safer if Roque had no special inducement to immediately lead a searching party throughout the city.

That is just what happened, and it proved not an overly-difficult task for the keen tracker to trace the boys to at least the vicinity of the place where they were hidden.

The men under the red roof were soon made aware of the lurking danger by the tooting of an automobile horn in the avenue bordering the grounds north of the house.

It was a telegraph code set in shrill notes, and it was apparent that Gervais, in alert listening attitude, had comprehended the message, even as the motor-car sounded the final blast in its swift passage out of sight and hearing.

The cool one, in most deliberate way, drawled the words: "Look out."

As effective as if a whole dictionary had been pumped through the window by Anglin's scouts.

The chief calmly resumed the disguise of wig and whiskers, while Fred blew out half-a-dozen candles with little waste of breath. With one tallow dip still alight, and shaded by hand, the doorman then mounted the ladder leading to the garret, thereby causing up there great commotion in the pigeon roost.

When Fred reappeared at the foot of the ladder, it could be dimly seen, he wore a broad grin and a wreath of cobwebs.

"When that flock arrives, empty-footed, old Winkelman will swear like a pirate."

Fred had turned every carrier bird but one loose in the night. The exception was fluttering in his hand, blinking its beady eyes at the glimmer of the lone candle.

Anglin had seated himself at the table and was writing a few words on a scrap of parchment, completing which he deftly attached the tiny roll to the pink leg of the feathered envoy.

Fred lifted the window a few inches and released the bird.

With the utmost care every bit of paper, every inch of thread was picked up and stowed away in the pockets of the three men preparing to vacate.

Billy and Henri were busily figuring in their minds just how they were going to come out of the scrape, when the creak of a shutter, under prying force, was heard on the lower floor.

"They're here at last," muttered Gervais, dropping a hand to his hip, on the revolver side.

Anglin laid a finger on his lips, enjoining silence, and tiptoed down the stairway, the others following in shadowy procession.

On the first floor the leader paused. The attempt to force the firmly hooked shutter had ceased, and no new form of attack was for the moment in evidence. Anglin had removed his cowhide boots, and, with velvet tread, then advanced the entire length of the long hall, motioning those behind him to remain where they were.

He was back again in less than five minutes, and whispered:

"The house, I believe, is completely surrounded. They are waiting for daylight, I suppose, to cinch some sure thing, the nature of which they are not quite certain. If Roque is along and thought I was inside, axes would have been working before this."

"They will find a lot here at daylight," chuckled Fred—"a lot of dust."

The party silently made their way through a side passage to what appeared to have been intended as the dining and cooking domain. Gervais had assumed the duties of guide, and he showed thorough acquaintance with the premises by first producing a dark lantern from a cupboard, and then moving directly to the black mouth of a steeply inclined flight of stone steps descending far below the level.

The spacious cellar was divided into sections by partitions of solid brick. But it was at the center of the foundation wall on the west where Gervais halted.

"Give me a leg up."

Fred gave his comrade the required lift, and Gervais secured a hand-grip on a big drain pipe that curved into the wall. He gave the pipe a strong-arm-twist, and the bull's-eye shine of the lantern revealed an aperture in the masonry, into which the climber squirmed.

Hardly had his feet disappeared, when he had turned about with his head out of the hole in the wall and a hand down to help the next comer to scale the space between the floor and the dislocated pipe.

Billy was given the hoist and crawled over the prostrate Gervais into the narrow passage above; Henri quickly followed, then Anglin, and finally Fred, who lent aid in pulling the pipe back to its moorings.

"'Snug as a bug in a rug,'" quoted Billy, who was really enjoying this method of getting out of a tight place, even though getting into another.

However, the rounded and cemented passage did not squeeze enough to be uncomfortable, and there was steady draught of fresh air coming from somewhere further ahead.

"The good man from whom you leased this property six months ago hardly counted this as one of the improvements you agreed to make," remarked Anglin as they started to wriggle through the drain.

Gervais laughed. "I didn't do anything to the pipe but what had to be done, and 'a stitch in time saves nine.'"

"It is likely to save three that I know of," grunted Fred.

"You can always count on Gervais to think for the future."

The man so complimented by his chief said nothing, saving his energy for the vigorous use of hands and knees necessary to make progress in the smooth channel.

The journey on all fours ended at a heavy grating, through which faint daylight was peeping. Through the barred opening the outlook was into a deep ravine, with a small stream coursing at the bottom, and a dense growth of small timber and bushes rising to the level on all sides.

Directly opposite the entrance of the drain, in a small clearing on the high ground across the gully, the broad windows of a stone cottage reflected the glare of the slowly rising sun.

"There is nothing else to do, my friends, but to lay low until brother Roque completes the scouring of this section. We are well on the way but not yet out of the woods, as the saying is."

This was the view of the chief, and his views were seldom questioned.

It was a rather gloomy prospect, this crouching wait in quarters so confined, but the secret service men counted nothing a hardship, and the boys had to possess themselves in patience.

The capacious pockets of the huckster's greatcoat, with which Anglin had not parted, despite its weight, in the long crawl, contained a supply of food, taken from the baskets before starting.

From the avenue that lay between the ravine and the grounds about the house which they had recently quitted, the cramped company in the drain could hear the rumble of traffic, and once they heard voices in close proximity to their hiding place.

"Giving them something to puzzle about, eh, Gervais?"

"Rather a fuddle for them, chief," agreed the cool one, "and the best of it all, they don't know whom they're after, unless it be these youngsters."

"Oh, I propose that the boys shall be found in due time, but the balance of us will keep dodging to the best of our ability."

"Some ability, too, believe me, boss," was Billy's contribution.

"Well, I believe we can hold our own," complacently observed Fred.

With the wearing of the long day, the prospect of liberation eased the trial of the later hours. As night fell apace, the first greeting to it was the glow of a lamp in one of the windows of the stone cottage.

Gervais moved close to the grating, and fixed intent gaze upon this illumination. In the course of a half-hour his vigilance was rewarded by a sight that he evidently anticipated. Somebody was repeatedly crossing and recrossing the patch of light, now and then deliberately standing in front of the lamp. That "somebody" was making dots and dashes as plain as day to the trained vision of the receiving expert.

"The coast is clear," he announced.

A little pressure and the bars were down.

Out into the night crept the weary five, with the luxurious experience of once more standing erect and having a good stretch.

Having replaced the grating in the drain entrance to a nicety, Gervais led the way down the steep slope of the ravine to the creek, which Billy and Henri attempted to drink dry, so great was their thirst.

"Now is a time when the best of friends must part," said Anglin. "I have been thinking it over, and the suggestion is that you, my young friends, must be relieved of any suspicion of willingly associating with suspicious characters. Gervais, Fred and I have our mission clearly mapped, the cause we serve is supreme, and the safeguarding I propose is of mutual benefit. With you boys here we can have no open acquaintance, and of us, as we are, you must claim no memory. To be brief, you have been detained by rough characters at the other end of town, and you will be there discovered at the roadside in the morning bound and gagged and stripped of all your possessions."

"I am afraid we are mighty poor picking," joked Billy, "but it is all right to give us the truss up, as we brought this shake-up to your door."

"That is neither here nor there now," consoled Anglin; "we must mend the situation as best we can."

And so it came about, at a point remote from the red roof, a passing policeman picked up two much hunted boys who were decidedly the worse for wear.

CHAPTER XII.
THROUGH FIRE AND FOG.

"You're a pretty pair, I must say."

True it was, the boys were not fixed for any dress parade when they first faced Roque, immediately after their delivery to the secret agent by the police authorities. The crawl through the drain pipe and the additional effort to give them the appearance of real victims of violent treatment, had served to convert the usually natty and trim youngsters into a couple of quite disreputable looking characters.

It is quite likely that Roque would there and then have put the returned wanderers through the "third degree" of questioning had it not been for a fortunate and welcome interruption in the shape of a messenger, who could not be denied, and who, it proved, brought tidings that wholly changed the line of thought of the stern chief.

"Take these chimney-sweeps to the tub and the clothesline," he gruffly ordered, and Schneider, half concealing a broad grin, accepted the service with celerity.

"You ought to have heard the boss when he found that you had not reported at quarters last night," said the red-topped aviator, when the trio were out of Roque's hearing. "He took the wind out of my sails, I tell you, and I am not considered slow in the cussing business."

"Where were you, anyhow?"

"In the hands of brigands, of course," gravely advised Billy, with a wink at Henri.

Schneider was so possessed with the prospect of some new and exciting move by Roque, indicated by the manner of the chief upon receipt of the message a few minutes before, that he did not burden the boys by forcing evasive explanations of their mysterious absence.

"If Roque had half a suspicion that we had been in company with his pet enemy, the prince of slyboots," confided Henri, when the chums were alone, "our joint name would be Dennis."

"Gee! If that fellow hadn't bumped in just at the right time, I think we both could have claimed the title of Ananias!"

Billy was a poor hand as a dodger of truth, and much relieved to escape the witness stand in this instance.

The kind of danger with which the boys best loved to toy was again speedily coming to them—the peril of aëroplaning.

Schneider brought the order to report forthwith at the aërodrome.

At the aërodrome an immense Zeppelin airship, as long as an ocean liner, had just been inflated. Roque was engaged in conversation with the captain of the great dirigible when Schneider and his young companions reached the grounds. The pilot of the huge craft and his assistants had already taken their places in the front gondola, the foremost end of which had been screened for their protection, and it was evident that sailing time was near. When the master mariner had exchanged a parting word with the secret agent he entered his room in the central cabin of the Zeppelin, which was in telephonic communication with the front and rear gondolas and other parts of the ship. In the meantime, Schneider had instructed the boys to give the No. 3's an inspection to see if the attendant helpers had properly prepared the machines for a long journey.

The young aviators then surmised that they were to travel as convoys of the monarch of the air, which even then was majestically rising.

Roque hastened to the machine in which Billy was already seated and waved a signal to the waiting Henri in the other biplane, containing also the redoubtable Schneider.

The swift flyers easily overcame the slight lead of the big ship, though it was making 40 knots, and took up the guiding positions. The flight was directly away from Lorraine and historic Strassburg.

"I wonder if our huckster friend is in the crowd back there?" was a mental question with Billy.

It was many a day before the young air pilot had a chance to again meet Anglin.

When this journey ended it was in territory remote from that of any former experience of the Aëroplane Scouts—a new battle landscape. It had snowed, and the drab, brown plain of Poland had turned to glistening white. The biplanes floated in a tarnished silver sky, which, pressing down, seemed hardly higher than a gray ceiling. The aviators landed on the clay bank of the winding yellow river, the Bzura, within 400 paces of the German trenches. Gun answered gun across the golden stream, shell on shell spattered into the soft earth, and rifles rattled unceasingly.

Schneider sniffed the powder smoke like a seasoned warhorse. "It's the life!" he exclaimed.

"And the death," added Roque.

He knew that men lay bleeding and broken on the banks of this yellow streak in the white picture.

"You're just right, boss," murmured Billy, nodding his hooded head, "the war map looks all red to me."

Roque, as usual, wherever he went or wherever he was, seemed to carry an Aladdin magic carpet on which to sail, for in the next flight of the biplanes a few miles distant he found a bright spot in this winter scene of rack and ruin—a clean, white lodgekeeper's kitchen, where a canary sang, and where the aërial wayfarers rested and were fed.

"I'll show you even better," he said, "when we break into Warsaw."

The chief also had a particular crow to pick with the defenders of the Polish capital. One of his men, for some time operating with the Russians, had been detected, and the end of a story of brilliant secret service achievement was marked by a little mound of earth in a Warsaw stable yard.

But for the present there were busy days ahead for the aviators in reconnoitering the Russian lines.

Most of the aërial work here was over a plain, flat as a floor. Black dots here and there marked isolated houses, and the Kalish road was bordered by a line of leafless trees with smooth trunks, which reminded the young pilots of a rank of grenadiers.

"What's that bunch over there?" queried Billy, nodding toward a group of horsemen, shrouded in long caftans, wearing lambskin caps shaped like a cornucopia, and bearing lances.

"They are Cossacks," replied Roque, from the observer's perch, "the strange fighters who never surrender."

Billy had later an opportunity for closer view of these reckless riders in the service of the Czar.

The flyers could see that the road below was this day crowded with the carts of refugees, trailing in endless procession, on the top of each vehicle the members of the family, the average one man to five women. The boys noted that there were not so many children here as they had seen among the homeless wanderers in Belgium. The same problem was here, however—what are they going to do?

"There they go again," cried Henri, referring to renewed outbreak from the long gray noses sticking out over the top of a brown gun emplacement—belching cones of death, and shooting red flare into the gray-white atmosphere. Then another noise out of the winter-worn copse of trees—pop, pop, pop, the notes of rifle fire, all raising a queer mist over the plain. With all this racketing no soldier could be seen at the point of fire.

If trouble was contagious, the biplane Henri was driving suddenly caught some of it; something went wrong with the motors, and it was a case of get down quick in the long slide, in which performance the young pilot excelled. He landed safely enough, but without choice of place.

The machine was stranded in Sochaezev, a city of the dead. Pale faces were still peering from some of the doors and windows, though almost every roof had been battered in, leaving only the stringers, reminding one of skeletons.

Billy had instantly volplaned in pursuit of the disabled biplane of his partner, and the two experts, assisted by Schneider, were speedily at the work of repair.

Roque impatiently moved about among the ruins, acting as a sentinel, and occasionally turning to the laboring aviators with muttered insistence for haste.

"Hist!"

With the chief's sibilant warning the boys softly laid down the tools and motor parts they were handling, and stood at attention. Schneider drew a revolver from his belt.

Roque, in crouching attitude, held an ear close to the frozen earth surface, and the others took example.

"There's a cavalry troop headed this way," hoarsely whispered Schneider. The pounding of many hoofs, growing louder and louder, was a sound apparent to each listener.

Then as a new diversion, out in the open field to the right of the road, down which the horsemen were galloping, rang out the rapid blows of pikes and spades on the ice-covered soil.

"They're throwing up kneeling trenches."

Schneider had a true ear for war moves.

The grating noise of the closing of a gun breech preceded a tense moment.

By the shifting of sound it was impressed upon the listeners that the oncoming cavalry had left the road and had swung into the plain on the left.

"We'll be between two fires in a minute or so."

This from Roque, as he rejoined his companions standing by the aëroplanes.

"Give us a precious ten minutes and we need not care," volunteered Henri, who had discovered the defect in the machinery which had brought them down.

"Get at it, then," urged Roque.

The boys did "get at it" so vigorously that they raised a perspiration, despite the frigid air.

"It's all right now," triumphantly announced Billy, hastily repacking the tools.

That they had been spared the time required to meet the emergency was due to the fact that the cavalrymen had diverted their course so as to make a sudden frontal charge on the artillerymen from the cover of the ruins.

"Now for a move backward," ordered Roque in low tone; "even though the gunners to the right may wear the gray we would have no show for recognition if we bounced up like a flock of partridges."

So the aviation party cautiously wheeled the biplanes in the deserted street as far as they could from the supposed line of the coming clash.

None too soon were they out of range, for with savage yells the Cossacks rode full-tilt from cover at the German guns and gunners in the shallow trenches.

Amidst the roar of desperate conflict the biplanes whizzed away like great arrows.

"Some speedy tinkering we did in that ghost town, Mr. Roque?"

"Nothing slow," assented Roque, leaning forward to give Billy a pat on the back.

"Where away now?" asked the pilot.

"Back to the lodge for the night," directed the chief.

No such comfort for the boys in the next flight.

They were booked for a journey to Przemysl, the vast underground fortress of Galicia, about which the Russian right end was then snapping like the tip of a whip around a sapling, and later surrounded on all sides by the Muscovite forces.

While viewing the first back-wash of the Austrian forces from the high tide of Russian invasion, the aviators had hurtled through a maelstrom of noise. The yells and shoutings of wagon drivers, the rattling of thousands of wheels over stony roads, the clatter of horses' feet made an indescribable tumult, and to this were added the sounds of infantry fighting.

Roque had reliable advices during one of the stops in the flight that the fortress defenders were still holding their own, and no Russian charge had as yet crossed the barbed wire mazes that circled the city.

Never since the memorable race at Friedrichshaven had the No. 3 type of biplane attained such velocity as in the finish of this forced run to the Galician stronghold, the final dash over the black-plowed farms through a wet fog and under fire of a Russian battery posted in the hills.

"I feel like I had been hauled through the lower regions by a nightmare," complained Billy, as he later sat with Roque, Schneider and his chum in the Steiber Coffee house.

"I will say," confessed Schneider, "that I never hit the wind so hard before in my flying experience. My eyes must look like two burned holes in a blanket."

"I might say, Schneider," remarked Roque, "that if it had not been for that timely fog you would have hit the ground harder than you ever did before. Those gunners on the hill could not have missed us if given fair sight."

"It has just occurred to me that they came pretty close, anyhow."

"They sure did, Buddy," laughed Billy, following this assertion by his chum. "I almost collided with a shell that sounded like a dozen factory whistles. By the way, Mr. Roque," he continued, "it looks like you were tied up here for some time to come. I don't see any way out of it."

"Do not lose any sleep over that problem, young man; if we got in we can get out. You ought to know by this time that there is always a hole in the air that cannot be blocked."

"You bet he's right," exclaimed Schneider, slapping his knee for emphasis.

"Hustle for bed, all of you, and stay there until you are called."

With this the chief faced the fire and lighted one of his big, black cigars. He had some thinking to do.

The boys were awakened the next morning by gunfire.