E-text prepared by Al Haines



THE SECRET WIRELESS

or

The Spy Hunt of the Camp Brady Patrol

by

LEWIS E. THEISS

Illustrated by Frank T. Merrill



[Frontispiece: no caption]



W. A. Wilde Company Boston ——— Chicago Copyrighted, 1918, by W. A. Wilde Company All rights reserved

THE SECRET WIRELESS



To

WALTER K. RHODES, A.M., E.E.,

PROFESSOR OF ELECTRO-TECHNICS IN BUCKNELL UNIVERSITY,

TO WHOSE KINDLY HELPFULNESS IS DUE WHATEVER OF TECHNICAL MERIT THERE MAY BE IN THIS AND COMPANION STORIES OF THE "WIRELESS,"

This Book is Dedicated



Contents

I. WHAT CAME OF HENRY'S IDEA II. HENRY OVERCOMES AN OBSTACLE III. THE WIRELESS PATROL PREPARES FOR ACTION IV. THE SCENE OF ACTION V. THE MESSAGE IN CIPHER VI. A NEW DANGER POINT VII. CONFUSION WORSE CONFOUNDED VIII. WHERE MONEY TALKED IX. A FRESH START X. THE PURSUIT IN THE DARK XI. AN UNSUCCESSFUL SEARCH XII. ANOTHER OBSTACLE XIII. WHAT HENRY DISCOVERED XIV. THE RIDDLE SOLVED XV. ANOTHER MYSTERY UNRAVELED XVI. AN UNEXPECTED MESSAGE XVII. A CHANGE IN CIPHERS XVIII. TOO LATE XIX. THE ENEMY ESCAPES XX. A CLUE FROM THE AIR XXI. THE CAPTURE OF THE SPIES XXII. A TASK ACCOMPLISHED



ILLUSTRATIONS

Frontispiece

Up came a sliding inner tube



The Secret Wireless

CHAPTER I

WHAT CAME OF HENRY'S IDEA

Henry Harper was sitting in the doorway of the workshop in his father's back yard, where the Camp Brady Wireless Club made their headquarters. He was reading the morning newspaper. Suddenly he sprang to his feet. His face grew black. His free hand clenched.

"That's terrible!" he exclaimed. "Terrible!"

He walked across the shop, spread the newspaper on the bench and began to read aloud the big head-lines that had so aroused him.

LEAK IN NAVY DEPARTMENT

Germans Knew of Departure of Transport Fleet First Contingent of Pershing's Men Attacked, by Waiting Submarines

"It's terrible, terrible!" repeated Henry. "Their spies are everywhere. They stop at nothing. Who could have been villain enough to give them the information? It is terrible!"

In his agitation Henry began to pace up and down the floor of the shop. His face grew blacker and blacker as he brooded over the story of treachery. Though Henry was not yet eighteen, he was affected far more deeply by the story than most boys of his age would have been. For when the Camp Brady Wireless Club, of which Henry was president, had been practising the previous summer, Henry had been called upon to replace one of Uncle Sam's radio men who was suddenly stricken with appendicitis, and Henry had taken the operator's oath of fidelity to his government. So to him treachery appeared doubly black.

For some moments he paced up and down the shop. Suddenly he stopped short. A new idea had come to him.

"How did they get the news to Germany?" he asked aloud. "Both the cables and the mails are censored—and besides the mails would be too slow. It must have been the wireless. Can there be traitors in the wireless service, too?"

Henry was silent a moment, his brow wrinkled in thought. "Never!" he cried suddenly. "Uncle Sam's radio men are true blue. It's a secret wireless! A secret wireless! The Germans have got a hidden station somewhere."

The black look left his face. The scowl was replaced by a gleam of joy. "That means a job for us!" he cried. "The wireless patrol can help find that station, just as we found the German dynamiters at Elk City."

For when the wireless patrol had been at Camp Brady only a few weeks previously, acting as official operators for the commander of the troops guarding that section of the country, Roy Mercer had picked an innocent-looking message out of the air one night and by accident had found a code message in it revealing a German plot to dynamite a great dam and destroy a munition city; and later the wireless patrol had run down the dynamiters themselves in the very nick of time, after the state police had failed to find them, and had saved the city.

With Henry, to think was to act. "I'll write Captain Hardy at once," he said to himself.

Captain Hardy was a young physician who had been leader of the club of boys that had camped on his father's farm near old Fort Brady, and that had subsequently become the Camp Brady Wireless Club. But Captain Hardy was no longer leader of the club. He had offered his services to his country, and was now Captain Hardy of the Medical Officers' Reserve Corps. It was his standing and his friendship with the Chief of the Radio Service that had made it possible to secure permission for the Camp Brady boys to act as radio men for the state troops the preceding summer, although the government had forbidden amateurs to send wireless messages. And Henry, believing that his idolized leader could accomplish anything, now cleared a space at his desk in a corner of the shop, and wrote him a long letter, setting forth all that was in his heart.

The promptness with which the answer came should have warned Henry that the reply was not the one he hoped for. But his faith in his leader was so great that he never doubted for a moment that if Captain Hardy favored the proposal, he could effect its accomplishment. With a shout of joy, Henry seized the letter from the hand of the postman and ran to his favorite haunt, the workshop, to read it. As he did so, the smile faded from his face and a look of utter despair succeeded it, for this was what he read:

"MY DEAR HENRY:

"It was a very great pleasure to receive your letter, with the little items of information about the members of the club, and your plan to be helpful in the present emergency. I know exactly how you feel. Every true American is filled with similar loathing for the treacherous enemies that infest our land, and with the same ardent desire to hunt them down and bring them to justice. You may be very sure that our secret service men are hard on the trail of many of them. Yet the very story of treachery that has so stirred your indignation shows that the secret service men cannot cope with them. But the fault is not with the secret service. It lies with Congress, which has persistently refused to appropriate sufficient money to make the service adequate. As far as it goes, it is the peer of any secret service. Of course help is needed, but I very much fear it is not the sort of assistance that the Camp Brady boys are prepared to give.

"You see, Henry, there are two possibilities. Either there is a leak in the navy department itself, as your story says, or else the sailing of the troops was observed at the port of embarkation and their destination guessed at. There is nothing you could do in the way of apprehending a spy in Washington, and I doubt if you could be of much assistance in detecting German agents in our ports. Of course I know how skilful the boys are with their wireless, especially you and Willie Brown, and I know what close observers Roy Mercer and Lew Heinsling are. And I realize, too, that in running down the dynamiters at the Elk City reservoir after both the Pennsylvania troops and the state police had failed, you proved that the wireless patrol was a mighty efficient organization. But that campaign was accomplished in the mountains and forests where your training in scouting and woodcraft has made you at home. Conditions in a great seaport would be so strange and confusing to all of you that I fear you would be more of a hindrance than a help.

"I am sorry about it, for I know how keenly you feel and how eager you are to help your country. The best way you can do that is to continue in school, learning all you can and making yourselves more and more efficient as wireless operators. In a very short time, I suspect, Uncle Sam will be in pressing need of good radio men. Then, although you are still young, your chance will come; for your ability is already known to the Chief of the Radio Service through your capture of the dynamiters last summer.

"As you know, our camp is just outside of Washington. I happen to be going into the city to-morrow. Of course, I shall take occasion to lay your suggestion before the Chief. But do not build any hopes on that statement. I have no idea anything will come of it. But it may help the Chief to bear you in mind later on. I am sorry to dash your hopes, but I cannot do otherwise than to tell you the truth. Of course if anything should come of it, I will let you know promptly. Remember me to all the other boys.

"Sincerely yours,

"JAMES HARDY."

Henry's face became longer and longer as he read. When he had finished the letter there was more than a suspicion of moisture in his eyes.

"Oh!" he cried, "if only I could be with Captain Hardy when he sees the Chief of the Radio Service, I'd make the Chief understand that we can help. We could be just as useful to the radio men as the Baker Street Irregulars were to Sherlock Holmes. Oh! I just wish I could be with him. I wonder when he will see the Chief."

Henry picked up the envelope and examined the postmark. "This was mailed yesterday morning," he muttered, "and Captain Hardy said he was going to Washington to-morrow. That's to-day. Maybe he's with him this afternoon. Maybe he went this morning. I'm sure he knows by this time what the result is. Oh! I wish I were with him. I'd just make that Radio Chief take us."

As he spoke a telegraph messenger entered the yard. He caught sight of Henry in the workshop door. "Hey!" he called. "Does Henry Harper live here? Got a message for him."

Henry was almost too much amazed to answer. He had never received a telegram in his life before.

"Hey!" called the messenger again. "Are you asleep?"

"No," was the answer, "and I'm Henry Harper."

"Then why didn't you say so?"

Henry ran forward and seized the yellow envelope. "Where's it from?" he asked.

"Washington," said the messenger.

"Washington!" repeated Henry. "Washington! Then we're to go."

"If you'll sign here," said the messenger, "I'll go. I can't stand here all day. Nothin' to pay."

Henry signed the messenger's book, then tore open the envelope and took out the following telegram: "Want you, Roy, Lew, and Willie to meet me Pennsylvania Station New York City Friday two P. M. for work suggested in your letter."



CHAPTER II

HENRY OVERCOMES AN OBSTACLE

Could the messenger boy have seen Henry after the latter had read the telegram, he would soon have changed his mind as to Henry's sleepiness. For a very brief space—just long enough to reread the message once or twice—Henry stood like one dazed, as motionless as a statue, and as silent as a sign-post. Then he gave a loud whoop and began to dance around the little shop. For a boy who was ordinarily so sober as Henry, such conduct was scandalously riotous. He skipped about the tiny wireless room, waving his hat in his hand, cheering for the Camp Brady Wireless Patrol, and making loud declarations as to what that organization would do to the enemies of the country.

Ordinarily Henry would have restrained himself. Not even the news that the Camp Brady Patrol had been selected to perform the wireless service at the guard headquarters the preceding summer had excited Henry as did this message from his captain. But that was scarcely to be wondered at. The work for the commander of the Pennsylvania guards had promised nothing but the sending of uninteresting and wordy despatches, though to be sure it had turned out quite differently before it was ended. But the task now in view promised excitement from the start. It breathed adventure, romance. To hunt spies—to trace traitors—to turn the searchlight on hidden crimes and dark deeds—to outwit clever men—to take a man's part in a man's world—to do deeds of daring and bravery—and above all to serve his country and save his fellows—these were the things that came into his mind as the probable results of the precious communication he held in his hand.

Forgotten were the tedious hours of monotony that his sober senses would have told him must make up the greater part of any such labor as that he was now about to embark upon. Forgotten were the dull, deadly dull and uninteresting days that his experience should have told him lay before him. In his enthusiasm Henry saw only the bright spots. The mental vision he looked upon glowed with rosy light. And Henry gave himself up utterly to enjoyment of the prospect.

So he danced and shouted and waved his hat, and cheered for the Camp Brady Patrol, until in his excitement he danced too close to the side of the tiny shop. His wildly waving hat came into contact with sundry tools and kettles and other metal implements hung up on nails to be out of the way. Down came saws and pails and a sprinkling can, and the hoe, and a dozen other articles in a noisy crash. It sounded as though a cyclone had suddenly descended upon the little shop, or a 42-centimeter shell had burst within. The exultant chant of the lone occupant of the building suddenly ceased. But its place was instantly taken by another voice as Henry's mother suddenly appeared on the back porch of the house, looking anxiously toward the workshop.

"Henry! Henry!" came her anxious call.

"Yes, mother," replied Henry, disentangling himself from the wreckage, and thrusting his head out of the shop door. "What is it?"

"Whatever are you doing?" demanded Mrs. Harper. "I thought the shop had tumbled in."

"It's only some things I knocked down," laughed Henry. Then his enthusiasm bubbled over again. "Just think, mother," he cried. "We're going! We're going! Captain Hardy has sent for us!"

Mrs. Harper looked at her son anxiously. His words meant absolutely nothing to her, for Henry had not told any one of his letter to his captain. Suddenly she feared that perhaps something had fallen on Henry's head and momentarily unbalanced him.

"Going?" she said. "Where? What are you talking about?"

"We're going to New York City to help catch German spies," cried Henry, beginning to dance about again in his excitement. "Isn't it bully! And we'll catch 'em, too, just as we did the dynamiters."

"I guess you're going crazy," said his mother. Then as Henry continued his demonstration, his mother said sharply, "You stop right there, Henry Harper, and tell me what all this nonsense means about German spies and New York and Captain Hardy. You know very well that Captain Hardy is in Washington with the army."

Henry at once calmed down and took a grip on himself. "Yes, mother," he said. "Captain Hardy was in Washington, but he is going to New York——"

"How do you know?" interrupted Mrs. Harper impatiently.

"He just telegraphed me——"

"Telegraphed you!" said the incredulous Mrs. Harper. "What would Captain Hardy be telegraphing to a youngster like you for, I'd like to know."

"In answer to my letter——" began Henry, but again his mother cut him short.

"Your letter?" she said. "What letter? I didn't know that you had written him a letter."

"You see, mother," said Henry patiently, "when I read in the newspapers the other day that the Germans had found out about the sailing of Pershing's men, and had sent submarines to lay in wait for them out in the ocean, the idea came to me that perhaps the wireless patrol could help to discover——"

"Henry Harper, I hope you never had the impudence to suggest that you youngsters could——"

"I did, mother. But I don't think it was impudence. I wrote to Dr. Hardy and asked if the wireless patrol couldn't help catch the spies who are sending news to Germany."

"Well of all things!" ejaculated Mrs. Harper. "What will you infants do next? Offer to relieve the President of his job?"

"Well, we did catch the dynamiters at the Elk City reservoir," protested Henry defensively. "And we did it after the state police and the national guards had failed. I don't see why we can't help catch German spies in New York just as well as in Pennsylvania."

"Humph!" said Mrs. Harper. "It's a lot of help you youngsters would be in catching real spies. You just happened to stumble on these dynamiters and now you think you can do thing. But that's the way with boys. They're all alike."

"But, mother," protested Henry, "boys can be useful in lots of ways. And just because they are boys nobody thinks of suspecting them."

"There's one place where a certain boy I know could be of a lot of use and never be suspected," agreed Mrs. Harper. "And that's at that woodpile back of the shed."

"Please don't interrupt me, mother," said Henry. "You asked me to tell you about our trip to New York."

"About your dream of a trip to New York," corrected Mrs. Harper. "You don't for one minute think you are really going to New York, do you?"

"Indeed we are," replied Henry. "And this is how it came about. When I read of the leak in the navy's secrets and the attempts of the Germans to torpedo our transports, I wrote to Captain Hardy about it. I told him we could be just as useful catching German spies in New York as we were in Pennsylvania. He answered and said he didn't think we could be of any use, but——"

"Showed his sense," interrupted Mrs. Harper.

"But he said," continued Henry, paying no attention to the interruption, "that he would mention the matter to the Chief of the Radio Service and let me know if anything came of it. And something has come of it, mother. Just think! We're to go. Here's the telegram itself."

Mrs. Harper took the yellow paper that Henry held out to her and read it slowly and carefully. "Well, I never!" she said at last. "I never did! But I don't know whether to let you go or not. Why, you'd be lost inside of ten minutes in New York, and instead of being a help to the police, you'd keep them busy hunting for you. I don't know about this. Wait till your father gets home and we'll talk it over."

"But, mother," protested Henry, "I can't wait. And we've got to go. The Chief of the Radio Service has asked for our help. That means the government wants us. If it wants us, it must need us. And we've just got to go."

"Humph!" said Mrs. Harper.

"And besides," added Henry, reading the signs in his mother's face, "Dr. Hardy is to be in New York with us, so we can't get into trouble."

"Well, that alters the case," said Mrs. Harper. "With Dr. Hardy to look after you, I reckon you can't go very far astray."

"Then we can go, mother?"

"I suppose so. I know your father thinks every one of us should do everything he possibly can to help win this war. But it gets me to know what you youngsters can do that will be of any use. Still, I guess the government wouldn't have sent for you if it didn't want you, and I won't stand in the road of the government."

"Hurrah!" shouted Henry. "Then I'm off to tell the others." And he darted out of the yard and was away like an arrow.



CHAPTER III

THE WIRELESS PATROL PREPARES FOR ACTION

At top speed Henry tore down the street.

Half a block from his home he passed a schoolmate.

"Hey! What's your hurry?" the latter called out, as Henry dashed past him.

"Wireless patrol ordered out!" Henry shouted over his shoulder, as he darted on down the street.

"Wait a minute!" called the other lad.

"Can't," cried Henry. "Got to get the patrol together to go on a spy hunt."

At the words "spy hunt" the other boy leaped forward and ran after Henry at top speed. "What's up?" he asked enviously, as he overtook Henry and raced along beside him. For the lad did not belong to the wireless patrol.

"Ordered to New York by the government," panted Henry, "to hunt for German spies."

The announcement had all the effect Henry intended it to have. For a full half minute his companion said never a word, but ran mutely beside him, his eyes fastened incredulously on Henry. Then, "Gee whiz!" he said. "You're not really goin' to New York!"

"Sure thing," panted Henry. "Just got a telegram from Washington."

That was too much for Henry's companion. "Gee whiz!" he said again. "I wish I belonged to the wireless patrol."

Henry looked at him sympathetically, half sorry that he had said what he had. "Maybe you will some day," he replied. "Good-bye."

They had reached the home of wee Willie Brown. Henry stopped abruptly and turned in at the open gate. He mounted the steps and rang the bell. Mrs. Brown opened the door.

"Is Willie—at home—Mrs. Brown?" he asked, all out of breath.

"Yes, Henry," replied Mrs. Brown. "You'll find him up in his room."

"Is he busy?"

"Oh! He's tinkering with his wireless, as usual," said Mrs. Brown. "But he's always glad to see you, Henry."

"He will be this time, I'm sure," said Henry. "The wireless patrol is ordered out on a spy hunt."

"What! Not again?" queried Mrs. Brown, in astonishment. "Where are you going this time?"

"To New York," rejoined Henry, and his voice plainly showed his exultation.

"Tell me more about it." Mrs. Brown was at once all seriousness.

Henry turned away from the stair door and explained the situation to Mrs. Brown, who was very sober. But when Henry said that Dr. Hardy had asked the boys to come and that he would himself be with them in New York, the serious look vanished from Mrs. Brown's face. "That's all right, then," she said. "If Dr. Hardy wants you and is to be there to look after you, it is all right. I am glad Willie has the opportunity to go. He has never been in a really big city."

Henry went on up to Willie's room and broke the news to him. And the sounds that came down to Mrs. Brown made her laugh heartily. But it was a laugh of sympathy. She remembered that she had once been young herself. Presently the racket up-stairs subsided. Then came the clatter of noisy and eager feet on the stairs. And a moment later Henry and Willie skipped out of the door, tore through the gate, and went racing up the street toward Roy Mercer's house.

But Roy was not at home. He was, as Henry had suspected he would be, at work in the garage where he had been employed during the school vacation. But Henry thought it would be well to secure permission from Mrs. Mercer for Roy to take the trip to New York, for she was inclined to be rather strict with Roy.

"Captain Hardy has just sent me a request for four of the boys of the wireless patrol to come to New York," said Henry, diplomatically, "and Roy is one of the four he wants. We came to see if he may go."

Mrs. Mercer looked at Henry keenly. "What are you going to do in New York," she demanded, "and who's to pay the bills?"

"I don't know exactly what we're to do," said Henry, "but we're to help the wireless service. I think they want us to listen in and pick up low-length messages that the high-powered government stations don't get. The government will pay our expenses."

"Humph!" said Mrs. Mercer. Then she was silent a moment in thought. "When does Dr. Hardy want you to go?"

"He wants us to meet him in New York at two o'clock Friday afternoon. That means we should have to leave here on the early morning train Friday."

"I don't know about this," said Mrs. Mercer. "All play and no work is just as bad for a boy as no play and all work. And Roy has done nothing but play all summer. He has been at that camp of yours ever since school closed. And besides, he is earning three dollars a week working at the garage."

Henry had feared that Mrs. Mercer would object to Roy's going. Roy's father had been sick and unable to work for some weeks, and Henry knew that the three dollars Roy earned each week were badly needed in the Mercer home.

"I think that the government will pay Roy more than he earns now," explained Henry. "And I hope that you will let him go because Captain Hardy wants only certain boys and Roy is one of them. He is very necessary to the success of our work."

"I'll see what Roy's father says," was the reply, and Mrs. Mercer vanished within the house.

Meantime Henry and Willie stood on the porch hardly daring to speak to one another, so fearful were they that Roy might not be allowed to go. When Mrs. Mercer suddenly appeared again and announced briefly that Roy could go, they thanked her, and as soon as they could get around a corner, they gave vent to their feelings in a loud whoop.

Lew Heinsling was picked up a few minutes later, with no objection on the part of his parents, and the three boys raced to the garage, where they imparted the news to Roy.

School, which normally should already have been in session, had been kept from opening by an epidemic of measles; and no one knew when it would convene. But there was no apparent chance of an early opening, for the epidemic was then at its worst. There was no obstacle now in the way of the four boys. Roy got his employer's permission to leave the garage for an hour, and the four boys hurried to the wireless patrol headquarters in Henry's shop, to discuss the adventure that lay before them.

That night the entire patrol assembled in the little workshop and those who were not to go enviously discussed the coming adventure with the four who had been summoned to duty. For no one in the patrol doubted that the expedition would end in adventure and excitement, to say nothing of the delights of a trip to the nation's metropolis. Their common experience in running down the dynamiters at the Elk City reservoir gave these boys the certainty that both adventure and danger lay ahead of their four lucky fellows. But could they have known how truly thrilling and adventurous were the days ahead of their companions; could they have foreseen all the strange and exciting situations that would confront their fellows; could they have guessed the part their comrades of the wireless patrol were about to play in wiping out this hidden menace to our troops on the ocean, they would have been envious indeed.

But they could not know these things. And they recognized the fact that Captain Hardy had asked for these four because of their superior attainments, because they were best fitted to do the work in hand. So the stay-at-homes loyally crushed down their feeling of envy and united in a hearty send-off for their fellows. Every member of the patrol was at the railroad station Friday morning to bid good-bye to their four comrades who were to play no inconspicuous part in the stirring days to come, and who were to make known to the country at large the name of the Camp Brady Wireless Patrol.



CHAPTER IV

THE SCENE OF ACTION

As the conductor shouted "All aboard!" the little group of boys on the station platform suddenly parted, and the four who had stood in the centre of the ring, vigorously shaking hands, now moved hastily toward the train and scrambled up the steps. The conductor waved his signal to the engine-driver and swung aboard. The locomotive bell began to ring, there was a hissing of steam, and a puffing of the great locomotive, and the train slid gently forward. On the car platform stood the four departing members of the wireless patrol, waving fond farewells to their less fortunate members. Then they turned and entered the coach, with the cheers of their comrades ringing in their ears, their hearts beating with high determination to give all that they had of strength and skill and courage and patience to the grim task that lay ahead of them.

In no time Central City was lost from sight. The familiar fields and woods vanished. The country grew strange. Soon they were passing through a region entirely unknown to them. But so busy was each boy with his thoughts that he hardly noticed what at other times would have held his closest attention; for the pictures in each mind were just as unfamiliar as the landscape through which they were speeding.

"What was to be the nature of their work?" each boy was asking himself. "Would they sit and listen in, as they had done at Camp Brady, or would they be set to roving about, trying to pick out suspicious characters, or detect suspicious acts? And what would New York be like? What was there about this great, roaring city of men that was so attractive, that drew such multitudes to it, that grew with such uncanny swiftness? What was New York like, anyway?"

And almost before they knew it, the train rolled into a tunnel, dived under a great river, and emerged again in a huge yard far below the level of the streets, that was filled with many tracks and closed in with enormous walls of cement. Then the train ran into a great shed and came to rest. The boys left the coach, mounted a long flight of iron steps and found themselves in the city of their dreams—New York.

And there, at the gateway, was their beloved captain. They swarmed about him and grasped his hand. Then Captain Hardy led them to a corner of the waiting-room that offered a little privacy, and there they sat down in a group, close to one another, to talk over the business that had brought them again together.

"As I wrote you in my letter, Henry," said Captain Hardy, "I was not at all hopeful that your plan would meet with official encouragement. But I had promised you that I would mention it to the Chief of the Radio Service and I did so. It didn't take him a minute to decide on it. To my surprise he said he wanted you. 'I haven't a bit of doubt,' said he, 'that the country's full of secret German wireless outfits. They are probably of small sending power and operate in unusual wave lengths. It is almost impossible for our regular service to detect them. In fact I don't know how we are ever going to locate them unless we organize the amateurs all over the country so that they can listen in and catch practically everything that goes through the air. We are not able to do that yet, but I shall be very glad to have the help of your boys. I've been mighty interested in the way they handled that affair at Elk City. They are experienced and have good sense. They should be very useful to Uncle Sam.'" Dr. Hardy paused and smiled. "You see," he went on, "the Chief has kept pretty close watch of you boys. He knows all about the affair at Elk City." And Captain Hardy smiled affectionately at his charges.

"What are the Radio Chief's instructions?" asked Roy. "What are we to do?"

"The Radio Service," replied Captain Hardy, "has no agencies for making arrests and detecting crime. So we shall work under the direction of the secret service and in cooperation with the police. And our first duty is to make ourselves known to both."

"If the Chief of the Radio Service wanted the wireless patrol," said Roy, "why did you telegraph for just the four of us? And why are we in New York instead of Washington?"

"You couldn't be of any use in Washington," said Captain Hardy, "but you may be of a great deal of service here. You see New York is a difficult place to guard. This is our principal port. It is so vast that it is next to impossible to watch all of it, and there are hundreds of thousands of Germans or people of German descent living here. The Radio Chief needs sharp eyes and ears as well as trained fingers just now, and he knows that you boys combine these qualifications. He suggested that I send for four of you and see what you could accomplish. I chose you four because you have shown the greatest ability along the lines necessary."

A flush of pleasure glowed in each of the faces before him. For a moment Willie Brown forgot where he was, forgot the crowd and the great station and the strange sights and sounds about him, forgot even why he was in New York, while his mind went back to that first summer at Camp Brady, when he had been the most backward, self-distrustful, helpless lad in camp. Now he was chosen to serve his government, to do work of the greatest importance for his country; and he had been selected because of his ability. No wonder Willie blessed the day he first saw Camp Brady. No wonder his eyes were wet with a grateful mist as he looked affectionately at his captain, who had made him what he was.

But Willie had little time for revery. Roy was speaking again, asking another of those sharp questions that showed very well why he should have been chosen as a spy hunter, or for anything else that required keenness of mind.

"What about yourself?" Roy was saying. "Do you have to go back to your medical duties? We can work ever so much better with you to lead us than we could with a stranger."

Roy alone had grasped the possibility that Captain Hardy might not be able to remain with them. Now every eye was fixed anxiously on Captain Hardy's face.

"No," he said, "I do not have to return to Washington. It is of the utmost importance to catch these spies and the government could well afford to give up one ordinary doctor in order to get four skilled spy hunters." He paused and smiled, then added: "So I have been detailed to special duty in New York."

The boys could hardly repress a shout of joy.

"And my instructions," continued Captain Hardy, "were to get into touch with the police and the secret service immediately. As I have told you, we must get acquainted with both. But before we do, I suggest that we take a look at the town where we are to work in the days to come. Let's be moving."

They rose and passed through the station. Its great vaulted ceiling, half as high as a church steeple, its huge flights of steps, its enormous corridors, its wonderful stonework, dwarfing into insignificance anything they had ever seen before, fairly awed the boys from Central City. It was Roy's keen eye that caught sight of the great maps of the world high up on the walls. The crowds of people coming and going hardly seemed like crowds, so vast was the structure. With reluctant feet the four boys pushed on. But when they had mounted the steps to the arcade and caught sight of the illuminated transparencies showing scenes along the railway's path, they came to a dead stop. For Willie Brown, with his almost uncanny eye for landscapes, at once declared that a certain picture represented a mountain scene not twenty-five miles from Central City; and when the others appealed to Captain Hardy, the latter confirmed Willie's statement.

When the four lads reached the sidewalk they were almost distracted. Thousands of people were hurrying along, passing in endless throngs up and down the street. Never had the boys from Central City seen people in such a rush.

"What's the hurry?" demanded Roy. "Why does everybody walk so fast? What's up?"

"Nothing," replied Captain Hardy, with a smile. "That's just the New York gait. Everybody walks fast here, and does everything else fast; and if you boys want to make a reputation in New York you'll have to hustle some. But I don't want you to make that kind of a reputation," he continued, hastily yanking Willie Brown from in front of a passing motor-car. "You will have to keep your eyes open here."

And indeed they had to. Motor-cars were rushing about as numerous as flies in August. Trolley-cars followed one another up and down Seventh Avenue in endless processions. Wagons and trucks stretched along the highway in slow-moving lines as far as the eye could see. Bells were ringing, whistles tooting, horns blowing, motor-cars honking, newsies shouting. The grinding of car-wheels, the rattle of carts, the clatter of hoofs on the asphalt, the shuffling of feet on the sidewalk, and a thousand other noises combined to make an indescribable and confusing roar. The noise and bustle were bewildering.

"I guess mother was right," thought Henry. "It would be mighty easy to get lost here. The wireless patrol will have to look sharp or the police will be called upon to find it."

And indeed there were so many distracting things that the four spy hunters found it difficult not to get lost. At every step something new and unfamiliar claimed their attention and caused them to pause and look about.

Captain Hardy let his charges go at their own gait. He paused when they wanted to look at something, took sharp care of them at crossings, and told them how to cross the streets so as to avoid accidents. And ever he kept his eye on them to see that none of the four became separated from the group. It pleased him to note how quickly they learned to avoid the traffic and dodge difficulties. Their training in observation had not been in vain.

To Herald Square the captain led his party. There, in a little eddy of sidewalk traffic, he drew them together.

"The streets that run lengthwise of the island," he said, "are called avenues, and the one before you is Sixth Avenue. The station we just left faces on Seventh Avenue. The cross streets are numbered, and the one we are on is Thirty-fourth Street. Broadway comes up the island on a long diagonal. Right here where Broadway, Thirty-fourth Street, and Sixth Avenue intersect, is one of the busiest corners in the city. Overhead are two elevated railway tracks. On the ground are six street-car tracks, crossing one another. Under the surface are two subway tracks. So you have three layers of people passing and repassing above or below one another. I want you to remember what I have said as to the arrangement of the thoroughfares—avenues run north and south, streets east and west. If you get that thought in your mind, you won't go very far out of your way.

"And there is one thing more to remember. In some cities, such as Philadelphia, the street numbers run 100 to each block. Here the houses are numbered consecutively, and you can't tell by a number where a house is. But if you should need to know, go to the nearest drug store. Every New York drug store has a city directory. And in the back of the directory you will find a table that will show you approximately where to find the street number you want. Don't forget. If you are to do effective work, you must become so familiar with New York that you can find your way around as readily as you can in Central City. Sometimes it may be necessary for you to go from place to place in the shortest possible time and you must know not only how to get there, but also how to take advantage of short cuts. We'll get some maps after a time and study them."

His young companions plied their leader with a thousand questions. They wanted to know the names of all the big buildings in sight. They had all heard of the Waldorf-Astoria Hotel and they gazed up Thirty-fourth Street at this well-known hostelry with much curiosity. They had heard of the Times Building and were eager to see it.

"We can't spend much time sightseeing just now," said Captain Hardy. "We must get into touch with the police and the secret service people and get our instructions. Then we will take a day or two, if possible, and see something of the town. It is most important for you to become well acquainted with it at once. But I guess we can take time to slip up to Times Square. It's only eight blocks up Broadway. Now I want you boys to see everything you can as we go along, and to try to remember all that you see. Wherever you go you must remember that you are in New York to detect German spies and presumably to run down German wireless outfits. We don't know where they are. We may be looking at one this very instant. So keep your eyes open. If you see anything that resembles a wireless outfit, or that might be used for sending messages, take careful note of it. And keep your ears open for suspicious conversations. Because you are boys, people will be less careful in their talk when you are present than they would be with older people about. The more youthful and unsophisticated you can make yourselves appear, the better it will be for your purpose."

Slowly the little party made its way up Broadway. By degrees the lads became accustomed to the roar of the traffic and the rush of pedestrians. At Times Square they paused for a look at the great newspaper building that gives the place its name, and at the great hotels rising on every side. Then they passed down a long flight of steps and found themselves in a low, vaulted, underground subway station.

"Makes you think of the dugouts on the firing-line in France," suggested the quick-witted Roy.

An instant later a train thundered up to the platform and the boys boarded it. A short ride and a short walk took them to Police Headquarters.

Captain Hardy sent his card to the Police Commissioner, with the request for a brief interview. A few moments later he had presented his credentials and introduced his companions, and four delighted boys found themselves blushingly shaking hands with New York's famous chief of police, Arthur Woods. Briefly Captain Hardy stated the purpose of his visit and related the story of the capture of the Elk City dynamiters.

"I recall the incident distinctly," said the Commissioner. "The newspapers were full of it. And I recall that when I read the story I wished I had as accomplished and clever a squad of boys to help me with some of my hard problems."

The four boys flushed with happiness. But they were too much embarrassed to make any reply.

"Captain Hardy," said the Commissioner, "what is your plan of action?"

"We have none as yet. We are to work under the direction of the secret service. But we have not seen Chief Flynn yet. The boys just arrived."

"Let me make one suggestion to you," said the Commissioner, turning again to the boys. "Before you attempt to do any detective work make yourselves familiar with the city. Get some maps and study them until you know every street and alley. Take your maps and go over the city on foot. Put several days in at it. Become acquainted with the water-front, the piers, the surface cars, the subways, the ferries. Learn the city so that you can get around rapidly. Make the acquaintance of as many policemen, wireless operators, secret service men, and other persons as you can. Don't forget that a kind deed or a thoughtful act will help you to make friendships quicker than anything else; and make all the friends you can. In police work you never know who will be of assistance to you. And above all things don't talk. Don't tell a living soul about your purpose or your plans. Let Captain Hardy do that if it is necessary. Secrecy is absolutely essential to the success of your work. Unless you can get along without betraying yourselves you may as well go right back home. Remember the spies you are after are also after you. If they learn what you are, they might even take your lives."

"Commissioner Woods," said Captain Hardy, after a pause, "I have been wondering whether or not these boys should have some kind of passes that will enable them to get through the police lines. There may come times when it is of the highest importance that nothing shall interfere with them. What do you think about it?"

The Commissioner considered for a moment. "If I were sure they could be trusted with——"

"They can," interrupted Captain Hardy. "Absolutely."

"Very well then."

The Commissioner pressed a button on his desk. A clerk entered the room.

"Make out special police cards for Captain Hardy and these four lads," he said, naming the boys.

Again he turned to the young spy hunters. "The cards you are about to get," he said, "will pass you by any policeman or put you through any police line. Do not let any one know you have them and never use them unless you absolutely must. It is best that not even the police should know who you are. Be very careful not to lose your cards."

"We will make some little cloth bags," said Henry, "and carry the cards in them inside of our underclothes."

"I see that you are resourceful," smiled the Commissioner.

The clerk returned with the cards and handed them to Captain Hardy.

"Before you go," said the Commissioner, "perhaps you would like to see our wireless department and get acquainted with Sergeant Pearce who is in charge of it."

He summoned a patrolman to guide them to the wireless rooms and wished the boys success.

A few moments later Sergeant Pearce was showing them the apparatus. Two operators sat at a wonderful Marconi outfit with receivers clamped to their ears. In another room various instruments were installed here and there, the walls were covered with diagrams of wireless instruments and outfits, and lines of men were sitting at long tables with receivers at their ears. It was the police wireless school. High above the roof the aerial hung, suspended between the main dome and a smaller dome at one end of the building.

"We are going to equip every station-house with wireless," said Sergeant Pearce, "and the men you saw at work in the school are being trained for operators. We have put wireless outfits on some of the patrol-wagons and on the police boat Patrol, so you see we can get into touch instantly with any precinct or with the Patrol no matter in what part of the harbor she may be. And when you have as big a harbor as we have, with several hundred miles of waterfront, that means something."

From Police Headquarters the little party went directly to the Post Office Building, near the Brooklyn Bridge, to see Chief Flynn. He was a large, heavy man, with black hair and eyes and a short mustache. He shook hands with each of the party, and gave each a searching look. He spoke quietly but right to the point.

"I had word from Washington about you," he said. "Do you know anything about the city?"

The boys admitted their ignorance.

"Then your first job is to get acquainted with New York. Get some maps and guide-books. While you are getting your bearings you can establish a wireless watch. I have a number of outfits in different parts of the city. For the next week or two, while you are getting acquainted with the city, I want you to maintain a twenty-four-hour watch at a place I shall send you to. Divide the time among you so that some one is listening in all the time. Here are the call signals of all the legitimate plants you will hear, either on land or water. Pay particular attention to call signals. If you catch one not in this list, be sure to get every word sent and let me hear from you at once. We have other operators listening in for messages of the usual commercial wave lengths and for very long wave lengths, so you need watch only for messages of less than three hundred meters."

He wrote an address on a slip of paper and gave it to Captain Hardy. "Go there," he directed. "A wireless outfit has been installed and accommodations await you."

He took the slip of paper from Captain Hardy and wrote some figures on it. "That," said he, "is my private telephone number. But do not bother me unless you get hold of something important."

In another moment the wireless party found itself in the rush and roar of lower Broadway.



CHAPTER V

THE MESSAGE IN CIPHER

The house to which Chief Flynn had directed the wireless patrol proved to be a private residence on a side street that ran between Central Park and the Hudson River. It was a tall house, standing two stories higher than any other structure in the block. Like most of its neighbors it had evidently seen better days. In places the brownstone front was cracked and great chips had flaked off. The broken stones in the long flight of steps that led up to the first floor were patched with colored cement that had faded so the patches stood out baldly. The brass handrail above the stone balustrade was battered and dirty. Altogether it was not a very attractive looking place.

The old lady who opened the door eyed them sharply.

"A gentleman named Flynn recommended me to your place," said Captain Hardy. "We shall need accommodations for quite a while."

"You must be the gentleman from Washington that he 'phoned me about. You are Captain Hardy?"

"I am."

"Come in," said the landlady cordially. "Any friends of Mr. Flynn's are welcome. Your rooms are ready for you. Mr. Flynn said you wanted to be together, so I have given you the entire top floor."

She led the way up one narrow stairway after another until the party reached the top floor. There she threw open the door to the front room and withdrew.

An exclamation of pleasure burst from the lips of the four boys. The shabby exterior of the house and the dim and dingy hallways through which they had come gave no hint of the cozy comfort that awaited them. The room they now entered was of generous size, with soft gray wallpaper and white woodwork. Along one side ran low, well-filled book-shelves. In the middle of the opposite wall, with fire-making materials already piled in it, was a small open grate, surmounted by an attractive mantel of white woodwork. There were a writing-table, a comfortable couch, and easy chairs. And what was most unusual for a city house, the room possessed windows on three sides—two overlooking the street and one giving a view over the housetops on either side. A door at the rear opened into a second room that was equipped as a writing room, with a broad table and several straight-backed chairs. Here, too, was an open grate set in a white mantel. In the room behind this were a number of cots. Back of all was the bath room. A snugger and more comfortable place it would have been hard to find. But nowhere was there anything that suggested a wireless outfit.

The boys looked at one another questioningly. "He said there was an outfit here," said Lew, "so there must be. But I don't see where it can be."

"It would be somewhere by itself," said Roy, "so that the operator wouldn't be disturbed. It must be on another floor."

"But if we are to keep a twenty-four-hour watch," argued Henry, "it ought to be right in our apartment."

"Let's look at the aerial, anyway," suggested Lew.

A door at the end of the hallway quite evidently led to the roof. They had noticed it as they followed their landlady up the stairs. Willie led the way through it and the boys found themselves on the roof, which, like the roofs of most city houses, was flat. Like its neighbors, also, this roof was encumbered with a number of long, wire clothes-lines, but the boys found nothing that suggested an aerial to them. Puzzled, they returned to their apartment.

Presently there was a rap at the door. Captain Hardy opened it and a man dressed as a waiter, whom they had seen in the hallway as they entered, stepped into the room.

"I came to show you your outfit," he said.

Stepping into the writing room, he grasped the corners of the mantel and gave a sharp pull. The entire upper half of the mantel swung outward and came to rest on the writing-table, revealing a compact but wonderfully well-equipped wireless outfit, including even a wireless detector for telling the direction a wireless message came from. The boys stared in astonishment while the waiter grinned.

"What kind of a boarding-house is this, anyway?" asked Lew.

"This ain't no boardin'-house," replied the man. "This is a sort of headquarters for secret service men from out of town."

"Where's your aerial?" demanded Willie.

"If you go on the roof you'll see it—that is you will if your eyes are sharp enough."

"I'll bet it's those wire clothes-lines," said Willie.

"Nothin' wrong with your eyes," said the waiter with a smile. "But I guess there wouldn't be, if the Chief sent you here."

Naturally each of the boys was eager to test the outfit before them. They crowded round it, sliding the coil, shifting the condenser, examining this and that, and voicing their approval and pleasure in the different instruments.

"We may as well begin our watch at once," said Captain Hardy. "Each of you will have to listen in six hours a day. If we divide the watches into two tricks of three hours each, it will be easier for you."

The matter was arranged accordingly, and the first trick given to the most experienced operator, Henry. After the others had seen him take his seat and adjust his receivers to his head, they withdrew from the wireless room.

But Henry was far from being in solitude. Sitting apparently alone, he was listening to a multitude of voices; for before beginning his vigil he wanted to test out his instruments and see how well they worked and how sharply they would register sounds. So he sat at his table, tuning now to this wave length and now to that, now catching a land message and now one from the sea. Distinctly he caught the signal NAA from the great navy wireless plant at Arlington. He recognized it before the operator had finished sending his call signal. Night after night with his home-made outfit at Central City, Henry had heard this station send forth the time signals at ten o'clock; and during his brief period as radio man for Uncle Sam he had often talked with Arlington, both sending and receiving messages from the great station. But though he recognized the voice, he did not know the language he heard; for Arlington was flinging abroad a message in the secret code of the navy. Press messages and commercial communications were buzzing through the air like swarms of bees. Orders to departing steamships came surging over his line. Suddenly a strong whining note filled the air, drowning out all other notes, and Henry knew the Brooklyn Navy Yard was talking. He caught messages from the Waldorf, from the Wanamaker station, from the police wireless. Never had he heard so many messages or imagined that the air could be so filled with talk. And had he not been a very able operator, he would have been so confused by the babel that he would have understood none of it clearly. But he tuned sharply, shutting out interfering vibrations, and caught clearly message after message. But every message that he intercepted was sent by a regularly licensed station.

After he had sufficiently tested his instruments, and assured himself of their ability to register even the faintest sounds sharply and distinctly, Henry shifted his coils and condensers again and began to listen in for messages of less than three hundred meters' wave length. Instantly the room that had hummed with voices grew silent as a cave. No message, no vibrations, no whisper of sound came to his waiting ears. For three hours he sat, continually shifting his coils, but he heard nothing. As well might he have sat three hours by a rock, waiting for it to speak. And well he knew that this was only the first of many long weary watches that would be kept ere the voice they looked for would come out of the air.

Vividly Henry recalled the long vigils at Camp Brady, when he sat for many hours at a time listening for the call of the dynamiters. He remembered how irksome that had been. He remembered the chill of the night and the silence of the great forest. Here the watchers would be more comfortable, but the vigil was likely to be as tedious and trying as their watch in the Pennsylvania mountains had proved. But that watch had been rewarded. The dynamiters had been located and captured. And Henry never doubted that this vigil, too, would meet with success. So he schooled himself to patience and keyed his ear and his instrument to the keenest pitch.

Meantime his companions had lost not a moment in beginning their study of the city. When Captain Hardy emerged from the wireless room, he ran his eye over the contents of the bookshelves; and one section he discovered was filled with maps and guide-books and local histories, not only of New York but also of other American cities. He found a large-scale map of the metropolis and spread it out on the table, true to the indicated compass points. Clustered about this outspread map, the other members of the patrol followed with eager eyes and retentive minds their instructor's every word.

Dr. Hardy called their attention to the contour of Manhattan Island, long and tongue-shaped, and running almost north and south. He showed them the main thoroughfares, the great arteries of north and south traffic. He traced for them the routes of subway, surface, and elevated car lines. Together they located the tunnels and the ferries. They studied the harbor and the different shipping districts, coming quickly to know where the transatlantic liners docked, where the coastwise steamers were berthed, and where tramp steamers could find safe anchorages. They examined the harbor and adjacent waterways. They studied the locations of police stations and hospitals, of passenger stations and freight depots. They noted the location of the forts. They identified the sites of the largest buildings.

When they had finished with Manhattan, they studied one by one the other boroughs—the Bronx, the boroughs east of Manhattan, Staten Island, and finally the Jersey shore, searching always for what would lend itself to spying or the use of a secret wireless. Especially they studied all that related to ships that cross the Atlantic.

Not in one evening or in one day was this accomplished, but through the long hours of many days, as one boy after another took his turn at the wireless. And between tricks at listening in or studying maps and guide-books, they roamed the streets, traveled on subway and surface and elevated trains, crossed the ferries, rode in the sightseeing motors, visited the bridges, the museums, the public buildings, and within a short time knew more about the topography and geography of the city than nine-tenths of the people who lived in it. As they became accustomed to the noise and the confusion and were able to find their way about with ease, they scraped acquaintances on every side, and soon knew a multitude of newsies, porters, policemen, truck drivers, car-conductors, and others.

Hour after hour, day after day, night after night, they listened in. A week passed. Then another went by. But excepting for one or two snatches of talk, seemingly innocent, the watchers at the wireless caught nothing.

Then, as Roy was listening in one noon while his comrades were down-stairs at luncheon, there was a sudden buzzing in his ear. Rapidly he shifted coil and condenser until the vibrations came sharp and clear. A call was sounding. 2XB was calling 5ZM. Roy seized his pencil and copied the signals, at the same time trying hard to locate the direction from which the signals came. It was well that Roy was a fast operator, for the message that followed came with such rapidity that it taxed Roy's ability to catch it. But he managed to get every letter. When the message was ended, Roy reached for his list of stations and rapidly ran through it. The stations he had overheard were not listed. There could be no doubt about it. He had caught a message from a secret wireless. He turned to the paper with the message. Here is what he had written down: SRPSTSNIAOLTMIXNREHONTSTFIRG. But he could make no sense of it. The letters would not form themselves into words, combine them as he would. He rose and ran to the dining-room with the paper.

Captain Hardy studied it for an instant. "Take this at once to Chief Flynn," he said. "He may want to ask some questions about it. Willie will relieve you at the wireless."

Several hours passed before Roy returned, and Captain Hardy began to fear lest, despite the training in the geography of the city, Roy had become confused and gotten lost. Then suddenly the door of the wireless apartment burst open and Roy flew in.

"Chief Flynn told me he thought his men could unravel that message and that I should wait a while," panted Roy, breathless from running up the stairs. "And they did get it. It's what they call a transposition cipher. Here is what it says."

He held out a sheet of paper. On it the letters Roy had picked out of the air were arranged in four lines, as follows:

S R P S T S N I A O L T M I X N R E H O N T S T F I R G

"Read down instead of across," explained Roy.

Captain Hardy studied the cipher a moment more, then read aloud: "Six transports left this morning."



CHAPTER VI

A NEW DANGER POINT

For a moment there was dead silence. Then Captain Hardy spoke. "You have done excellent work, Roy," he said. "Beyond doubt this is a message from a German spy. It is fortunate you caught this particular message, for it proves that, whether there is a leak in the navy department or not, the Germans are watching our ships here in New York. Did you catch the direction this came from, Roy?"

"Yes, sir. I marked the direction on the blotter beneath the detector."

"We'll take a look at it," said the leader, and the little band entered the wireless room, where Lew was now on duty.

On the white blotter they found a long black line, tipped with an angle mark like an arrow-head. Captain Hardy got a map of the city, and spreading it on the table true to the compass points, stretched a yardstick across it in the direction indicated by the arrow.

"Hoboken," he muttered. "The arrow points to Hoboken." For a moment he studied the map before him. "You will remember," he said, looking up, "that Hoboken is the point on the Jersey side of the Hudson where there are such great railroad freight yards and such huge piers. Many Atlantic liners sail from Hoboken. Evidently the Germans are watching there. Of course they would be. Their spies are informing other German agents every time a troop ship sails. And somehow they get that news to Germany. It's a terrible menace to our army, boys. We must put an end to it."

"We will," came the reply from four sober-faced boys.

"It's going to be a long task, boys," said Captain Hardy. "Get your hats and we'll take a look at Hoboken."

Leaving Lew at the wireless, the four others set out. They rode for a distance on a Ninth Avenue elevated train, then walked to the ferry, and in less than an hour of the time they left their headquarters found themselves in the great Jersey shipping point.

Never had the boys from Central City seen anything quite like the water-front at Hoboken. The level ground was one great maze of railroad tracks, freight depots, warehouses, and pier sheds. The wide thoroughfare running along the waterfront presented a scene of bewildering confusion. Trolley-cars, steam trains, motor trucks, horse-drawn vehicles, and other conveyances were moving this way and that. Whistles were tooting, motors honking, bells ringing, drivers swearing, policemen shouting orders. Pedestrians were dodging in and out, messenger boys were darting here and there. Porters were carrying bundles on their shoulders, laborers were wheeling materials in steel wheelbarrows, lines of heavily laden trucks were passing into steamship piers, and guards and watchmen at every entrance were closely scrutinizing all who approached.

The four observers walked slowly along, studying every foot of the way. High fences had been built here and there to hide what was going on behind them. Covered ways led from railway terminals to pier sheds so that none could see what had come by train. Even the gangways to the ships were screened. Every precaution had been taken to baffle curious eyes.

"They've done their best," commented Captain Hardy, "but they can't screen a ship on the river, and the Germans know when our transports sail, even if they don't know what's in them. Any one with a good glass can look out from any house along the river front and see clearly every move made by a steamer. Let's take a stroll among these houses."

They left the bustling water-front and passed to the higher ground where stood the city proper. It was like most other American municipalities—dirty, dingy, and unattractive, a hotchpotch of buildings with no architectural unity. But it had one feature possessed by few cities—an outlook on a great and busy harbor.

As the boys stood looking at the rolling Hudson below them, watching the ferry-boats come and go, like huge shuttles in a giant loom, following the movements of steamers, and tugs and tow-boats, and tracing the circling flight of the gulls, they forgot entirely the errand that had brought them. Presently their leader broke the silence.

"We shall have to get to work," he said.

Starting at one end of the street, they walked slowly along its entire length, studying every house that fronted on the river. They saw at once that their task was hopeless. Square after square the houses stretched in unbroken blocks. A hundred spies might be living in those houses and no one be the wiser. A hundred wireless outfits might be flashing messages among the clothes-lines on the roofs and only a roof to roof survey would reveal the fact. But it was not necessary to run even so slender a risk of discovery. As the wireless patrol knew only too well, an aerial would work with great efficiency even though it were strung in a chimney or erected entirely within doors. Yet the little party continued its investigation until dusk, scanning every window whence a glass might be directed toward the river, and threading alleys and scrutinizing the wires of roofs and yards. But nowhere did they see anything to arouse their suspicion.

"We may as well go back, boys," their leader said at last. "We shall have to depend upon our ears rather than our eyes if we are to catch these villains. But we have made progress. We know where they are. We have limited our field of observation to one place. Now we shall have to do as we did at Elk City. We shall have to get two portable sets with compact detectors and begin a watch in Hoboken. We'll have to find this hidden wireless by triangulation, just as we caught the dynamiters. But we haven't enough of a force to maintain two watches. We shall likely have to send for more of the boys to come on."

They recrossed the river and made their way back to their headquarters. Lew had heard nothing. He was relieved by Henry.

The others went down to dinner, and food was sent up to the lone watcher. But when his trick was ended, he made the same report that Lew had rendered. He, too, had heard nothing.

"Doubtless," said Captain Hardy, "they use their wireless seldom for fear of discovery. Probably they send a message only when troop ships have actually sailed. That is likely the reason it was such a long time before we caught the first message. And it may be just as long before we hear another. But when it comes, we must be ready with our two detectors. I'll see Chief Flynn about them in the morning. And I'll tell him what we have learned in addition to what the cipher message told us."

"I wonder," said Roy, "how the secret service men ever unraveled that cipher. I could never have done it. I was looking for something like the code message we caught at Camp Brady."

"It probably was not very difficult, Roy," replied Captain Hardy, "or it could not have been fathomed so soon. I believe that most cipher messages to-day are like the one you caught at Camp Brady. Apparently they are innocent messages but they have a hidden meaning. The most difficult cipher messages, I have heard, are of the substitution kind, where many alphabets are used. It is pretty difficult to decipher such messages unless you have the key word."

"Then why didn't the Germans use a substitution cipher when they sent this message about the transports?" asked Willie. "Then we might never have been able to tell what they said."

"It was hardly worth while, Willie. They know the authorities are listening for their messages. It made no particular difference if the contents of this message were known. But when they send out an order for a spy to do something, I have no doubt they use the most difficult code they can devise, or at least one that they believe only the spy will understand. So we may expect to catch messages in different codes before we are through with our work."

Captain Hardy rose and began to look along the shelves of books. "Here is a volume," he said presently, "that will tell us a great deal about cipher messages."

He had just laid open the book when Roy rushed in from the wireless room. "I've got another message," he said, holding out a paper on which was a long string of letters.

"I wasn't expecting another message so soon," said Captain Hardy in surprise. Slowly he read the letters on the paper Roy had given him:

"FTSTITEIAFTDLLTNSYWTORPSLHVNRLEEYLIOTEIH UAOSEIEGGEVNCENDRRTERNRADSNLEEITOCGEOSHM."

"It looks like the same cipher used before," he went on. "If it is, we can unravel this message without bothering the secret service. At any rate we'll make a try at it. Where's that other message, Willie?"

The first message was brought. Captain Hardy spread it on the table and the group bent over it.

"The letters divide evenly into four lines, you notice," said the leader. "Let's see if this message will do the same."

He counted the letters with his pencil. "Eighty," he announced. "That would make four lines of twenty letters each. We'll try it."

Rapidly he copied the first twenty letters. Below them he made a second line of the next twenty letters. Then the third set of twenty was written down. As he began the fourth row the three boys at his side held their breath.

"He's got it," Willie Brown cried, as Captain Hardy wrote down the first letter. "He's got it. It spells four."

Rapidly Captain Hardy finished out his line. The letters he had written down read like this:

FTSTITEIAFTDLLTNSYWT ORPSLHVNRLEEYLIOTEIH UAOSEIEGGEVNCENDRRTE RNRADSNLEEITOCGEOSHM

He picked up the paper and slowly spelled out the following message:

"Four—transports—sailed—this—evening— Large—fleet—evidently—collecting— No—destroyers—with—them."

For a moment there was complete silence. Then Henry spoke. "They can see everything in Hoboken," he said. "It's a wonderful place to spy from."

"That message didn't come from Hoboken," said Roy, who had been listening to their conversation with one ear while he kept his receiver at the other. "It was for 5ZM all right, but it was signed 2XC instead of 2XB and the detector doesn't point toward Hoboken."

There was a rush for the wireless room. Captain Hardy seized a map, spread it on the table, and again applied the yardstick, extending it in the direction indicated by the detector. The stick pointed straight toward the Narrows, at the entrance to the harbor.

"That message came from Staten Island," said Captain Hardy with conviction. "They have got two secret stations."



CHAPTER VII

CONFUSION WORSE CONFOUNDED

As the possibility of this new difficulty rose before them, the members of the wireless patrol were almost staggered. They knew how difficult it had been to locate the hidden wireless in the mountains at the Elk City storage reservoir, where there were no other wireless plants to distract them and no houses to conceal the apparatus. The obstacles now before them appeared almost insuperable.

The silence was broken by their leader. "I suppose we shall not learn anything, but at least it will be better to look the ground over. So in the morning we'll run over to Staten Island."

Morning found Henry on the wireless watch. Lew's trick was to follow. The two others and Captain Hardy left the house immediately after their breakfast and set off for Staten Island. In order to see something of the city as they journeyed, they went on the Ninth Avenue elevated road, and in half an hour found themselves at South Ferry, whence the city-owned ferry-boats leave for Staten Island. It was their first visit to this ferry and they were impressed by the fine waiting-rooms and the magnificent ferry-boats.

The trip down the harbor thrilled them with pleasure. The narrow channel between Manhattan Island and Governor's Island seemed to be filled with snorting tugboats, strings of barges, great floats carrying many loaded freight-cars, puffing steamships, and even sailing vessels. Whistles were tooting on every side as pilots signaled to one another.

"I don't see how they ever manage to keep from smashing into one another," said Willie as he stood with wide eyes, watching the rapidly moving craft about him.

"They don't always," said Captain Hardy. "But accidents are surprisingly few."

Hardly had they gotten up speed before they passed close to Governor's Island, the military reservation which was the army headquarters for the Department of the East. With great interest they looked at Castle William, the great circular stone fort, now useless for protection, but venerable with age and tradition, that stood at the western edge of the island.

Soon they were past the island and out in the open bay. Far to the left were the Brooklyn shores, with their great shipping terminals and stores and clustered steamers. On the right, and still more distant, ran the low Jersey coast, almost hidden in fog and smoke. Against this dull background towered the Statue of Liberty. Reverently the boys stood looking at this great image, known the world over as no other statue is known, and symbolic of all a free earth holds dear—symbolic of that liberty, fraternity, equality that the free men of the world are giving their lives to preserve. A mist rose in their eyes as they looked at this symbol of that which they, too, were giving their devoted efforts to preserve—their homes, their families, their freedom. And on every face came a set expression of determination that, even though the countenances wearing it were youthful, boded no good to the treacherous enemies of freedom whose trail they were that very moment following. Then they flashed past Robbin's Reef light and snuggled into their slip at Staten Island.

Before them towered the community of St. George, straggling, like some old world village, up the sloping streets to the heights. Quickly they climbed a winding road that led to the top of the hill. Like Jerusalem the golden, the village about them was beautiful for situation. For miles it commanded an unobstructed view in almost every direction. To the north were the rolling reaches of the Upper Bay across which they had come, with the tall sky-scrapers of Manhattan towering heavenward in the background and looking so near at hand that it was hard to believe that they were six miles distant. Shaped not unlike a pear, the great Bay tapered to stem-like dimensions as it flowed to the east of Staten Island and found its way to that greater sheet of water, the Lower Bay. On the opposite side of this passage rose the bluff shores of Brooklyn. But the Staten Island shore towered high above everything else. On opposite sides of the narrowest parts of the channel to the sea were forts. And it was to this very Narrows that the wireless detector had pointed when Roy caught the message on the previous night.

"From somewhere in this neighborhood that message came," said Captain Hardy. "And beyond a doubt it came from some house on the slope before us. From this view-point an observer can see everything that takes place in both Upper and Lower Bay and spy on every vessel passing through the Narrows. With a powerful glass an observer on these slopes could almost distinguish the buttons on the sailors' clothes or read the compass on the bridge of a ship. Let us see what we can find."

For a mile or two they walked leisurely along the brow of the hill, carefully examining every house that possessed a good outlook over the Narrows. They found many such, but as was the case in Hoboken, the houses were as like as so many peas. In location or construction there was nothing that would direct the finger of suspicion to one house rather than another. Any house with an unobstructed outlook might harbor a spy.

When they had gone far enough along the brow of the hill Captain Hardy said, "Let us go back along the slope. I suspect any observer would get as near to the water as he could and yet have sufficient elevation for a wide view. I believe the place we are looking for is somewhere below us."

They climbed down to a lower level and began their return walk. On the slope the buildings were not so close together. There were more open spaces, more undeveloped stretches where trees yet remained and thickets of underbrush still stood undisturbed.

"These houses would make better radio stations than those so closely crowded together, I should think," commented Captain Hardy.

Slowly they sauntered along, stopping near every suspicious house, ostensibly to view the landscape, and giving it a searching examination as they took in the view. And so artfully was their work done that no one watching the eager group, looking now here, now there, would have dreamed that ships and shipping were the last things they were interested in.

Slowly they worked their way along the slope, now climbing to higher levels, now descending to lower, as it became necessary to view a habitation from one side or the other. But search as they might, nothing stood out in any place that was of a suspicious nature. There were no questionable wire clothes-lines, for here every one seemed to use cotton lines. No flagpoles rose aloft, up which antennas wires could be hoisted in the guise of halyards. No kites flew from back yards. No lightning-rods rose suspiciously above the housetops. There were no tall chimneys inside which hidden wires might be stretched. Nowhere was there anything at which they could definitely point the finger of suspicion.

Almost had they given up hope of finding anything that would help them, when they came to a place where the slope jutted out sharply for a little space, like the nose on a human face. The ground sloped outward for a distance at a gentle angle, then dropped precipitously many feet. But on either side of the nose of land the even slope of the hill was unbroken, just as human cheeks continue their uninterrupted slope from the forehead. Perched on this nose of land was an inconspicuous little house. As the surrounding land was too steep for habitation, this house stood by itself, the slope for many yards on either side being overgrown with bushes and undergrowths, while a considerable stand of pines grew at one side. The fenced-in yard of this house was large, and by an ingenious system of curves a roadway had been built from the public thoroughfare up to the little house. Evidently the owner possessed a motor-car, for a tiny garage was snuggled into the hill beside the dwelling.

But the thing that at once attracted the little patrol was the view afforded by the location. Indeed it was the view-point strategically; for the jutting nose of land gave an unobstructed outlook toward both Bays which could be had from no other location on the same level, while the Narrows lay immediately below the house and so close that it seemed as though one could throw a stone from the little house into the water.

For several minutes the three searchers stared at the structure before them. "I believe," said Willie, in the language of blind man's buff, "that we are getting hot."

"Let's look at the place from the other side," suggested Roy.

Slowly they sauntered along the highway, now examining the Narrows, now watching some ship in the offing, but gradually working their way to the other side of the little house. Everywhere except at the rear of the building, where the hill rose steeply, ornamental rows of windows had been built into the structure, giving an uninterrupted view, north, east, and south.

"I'll bet there are no partition walls in that floor," said Roy, "and if there aren't, anybody could sit in the front of the house and look in three directions by merely turning his head. Why that place is just made for spying on shipping."

"And it's exactly where our wireless pointed," said Willie.

"I wonder how we could get into the place and examine it."

"You mustn't think of such a thing," said Captain Hardy. "If there is a wireless outfit there, you may be sure that it will be as effectually secreted as the one in our rooms is, and you would never find it. But you would certainly alarm the people in the house, and the Chief warned me that under no circumstances should we alarm the people we are watching. We must get a complete case against them before any move is made."

"But if this is a wireless station, how are we going to know it unless we search the house?" demanded Roy.

"We shall have to keep a watch on the house itself and try to trail everybody who goes in or out. And we shall keep up our wireless watch. If messages are coming from here we shall run them down just as we intended to run down the Hoboken messages. This place is so much better for spy work, being near the forts as well as the waterways, that we'll drop Hoboken and centre our efforts here. But I don't know just how we'll do it. I'll have to let the Chief outline the plan. We may have to move down here. But in the meantime you boys can keep the place under observation very easily from some of these thickets."

The three went on down the road and passed out of sight of the house, laying their plans as they went. Arrived at the road to the ferry, they separated, Captain Hardy continuing on down to the wharf, while Willie and Roy turned about and retraced their steps. While Captain Hardy was speeding back to Manhattan to consult the secret service men, the two young scouts made their way to a turn of the road whence they could barely see a gable of the house on the cliff. They had not met a soul. They left the highway and scrambled up the slope to a dense thicket of underbrush. Screened by this, they cautiously approached the house and made their way unseen into the little stand of pines they had previously noted.

The cover was good. The pines on the outer edges of the stand, where the light was ample, branched close to the ground, making a dense hedge. Behind these protecting branches the two boys could move freely without fear of discovery. By mounting upward a little distance, they had a perfect view of the house they were watching, and could see all who entered or left it. They found some limbs where they could sit comfortably and took up their vigil.

"Captain Hardy said we must trail anybody who came out of the house," said Willie. "If we follow them on the road we could be seen and we might be suspected. How can we trail them without being seen?"

They looked around. Higher up the slope ran another road, so hidden by shrubbery and bushy growths as to be almost invisible from below. A person walking along this road could easily follow one on the highway below without being seen. A brief study of the slope also showed them a bushy way by which they could scramble unseen up to this road.

Now they gave their undivided attention to the house before them, studying every feature of house and grounds that they might be able, if it became necessary, to make their way safely about the premises. But no one came to the house, no one left it, no one appeared at a window, and there was no sign whatever that a living being was in the house.

The minutes began to drag. It was uninteresting to sit and scrutinize a house when there was so much of real interest to see. So between glances at the home on the cliff, the scouts began to study anew the wonderful harbor that so fascinated them.

Again they studied those distant sky-scrapers, which looked, at the distance, like dream buildings, deceptive structures of the clouds. The waters intervening were palpitant with life. As an hour passed, and then another, the young watchers gave more and more attention to the landscape and less to the house near by. The air was vibrant with the tooting of whistles. The wind was sweeping the water before it in graceful waves. The passing steamers churned it into yeasty foam. Great sailing ships came surging in from the deeps, deck-laden with heavy cargoes, parting the water with their high bows, their sails bellying in the breeze and shining white in the sun. Tugs passed restlessly to and fro, dragging behind them long strings of coal barges. And once a great ocean liner came in through the Narrows, making the very hills vibrate with the thunder of her whistle. Intently the boys watched her as she slowed at quarantine and the port physicians boarded her. By mere chance Willie turned his glance toward the house on the cliff, and there, close to the front windows, stood a man with field-glasses to his eyes, studying the liner in the Narrows below.

"Look!" gasped Willie. "There's a man in the window!"

But before Roy could turn his head the figure had disappeared.

"We almost missed him," said Willie. "We're poor scouts to forget what we are about."

They centred their gaze on the near-by house. Forgotten was the glorious picture spread before them, forgotten everything but the glass-fronted dwelling and the invisible man with the field-glasses. But look as they would, they could see nothing further of a suspicious nature. Another hour passed. Dinner time had long gone by. The one o'clock whistle had blown. And their own stomachs told them accurately what time it was; but they would not leave their post. Now that they had once scented their quarry, as it were, or believed that they had, they were like hounds on the trail. Their training at Camp Brady now showed its effect.

But the hours passed, the afternoon waned, and nothing further occurred to draw their attention to the little house. Gradually their vigilance relaxed. Their eyes wandered again to that fascinating harbor scene, to the never-ending moving picture spread before them. Again they saw tugs and ferry-boats plying busily back and forth, and the flashing sails of great schooners. But presently they saw something like nothing they had ever beheld. Far in the distance was a line of moving objects, gliding through the waves in stately fashion, approaching one behind the other at equal distances. Just what was approaching the two scouts could not at first determine, so indistinct in outline were the moving bulks. But presently, as the oncoming objects drew nearer, the watchers saw that they were great ships. But they looked unlike any ships they had ever seen or heard of. They seemed to be of no color and of every color. They were streaked and splotched in the most curious way. They looked as though some giant hand had flung eggs of different colors against their sides.

The boys looked at one another in astonishment. "Well, what in the mischief ails those boats?" demanded Roy.

They were silent a moment, becoming more amazed than ever.

"I know," cried Willie suddenly. "They're camouflaged. They must be transports." He turned his head for a glance at the house. "Quick!" he said. "There's the man at the window again."

For some minutes the figure before them stood motionless except for the movement of his field-glasses, with which he swept the oncoming fleet of transports. Then he drew back from the window again. The boys kept their eyes fastened on the little house. For a long time nothing occurred. Then a grocer's boy came in sight, struggling up the highway with a basket of supplies on his arm. The watchers paid small attention to him until he turned suddenly into the driveway leading up to the house. A moment later he had disappeared within the building.

"He's only a grocery boy," said Roy.

"We'll have to watch him, anyway," said Willie. "I'll follow him when he comes out and you watch the house."

They had not long to wait. In a few minutes the boy came out, his basket empty, and went skipping down the hill. Quick as a flash Willie scrambled to the roadway above, and, screened by the shrubbery, followed on the higher level. A quarter mile toward the ferry the two highways came together. Willie reached the intersection at almost the same time as the grocer's boy. Each took a glance at the other and kept on his way, Willie dropping a few yards behind the other lad.