The Secret Wireless; Or, The Spy Hunt of the Camp Brady Patrol

by Lewis E. Theiss

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 coöperation 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:

"FTSTITEIAFTDLLTNSYWTORPSLHVNRLEEYLIOTEIHUAOSEIEGGEVNCENDRRTERNRADSNLEEITOCGEOSHM."

"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.

A quarter of a mile further on the slope changed and the district was thickly built up. The errand boy soon entered a store. Willie had just time for a quick glance at the sign on the window. It read, "Fritz Berger, Fancy Groceries." Then Willie opened the door and followed the errand boy into the place.

A florid, burly man with upturned mustaches stood behind the counter. The errand boy was talking to him. In his hand he held a silver dollar.

"Here is the money for Mr. Baum's sugar," he was saying.

"Good!" said the grocer, seizing the coin, which he dropped in his pocket. Then he turned to Willie. "Well?" he said inquiringly.

"Sugar," said Willie. "I want five pounds of sugar."

"I have no more," said the grocer. "It is all sold."

"Pshaw!" said Willie. "Where can I get some?"

"I don't know," said the grocer.

"Got any candy?" asked Willie.

"Sure. In that case."

Willie walked to the show-case and slowly examined the stock. "Give me ten cents' worth of those chocolates," he finally ordered.

The storekeeper weighed out the candy and dumped it in a bag. He took the proffered dime, dropped it in his till, and turned away.

Willie left the store and stood for a moment undecided as to which way to go. "Nothing doing there," he said to himself. Then he turned a corner and started down the hill. The supper hour was approaching. People were coming up the street from the ferry, homeward bound from Manhattan. A motor-car came chugging up the road and drew close to the curb. The driver turned his car about, clamped on the brake, and stepped out, leaving his engine running. Willie went on down the street and was soon in the midst of a throng coming up from the ferry. He stopped to look at a jeweler's clock, turned about, and started on his way to rejoin Roy. Suddenly he heard the softly whistled signal of the wireless patrol. He turned sharply about and saw Captain Hardy across the street. He dodged a motor-car that was rooming down the hill and crossed to his captain. There had been no sign of life about the little house since the grocer's boy came out.

"Come," said the leader. "I have seen the Chief and he is going to arrange it so that we can watch this place in comfort. We will go back home now."

They climbed cautiously to the road above. "By George!" exclaimed Captain Hardy suddenly. "You boys haven't had a bite to eat since breakfast. I forgot all about that."

"How about yourself?" asked Roy.

"Well, I haven't either, but that's different. I've had a chance to get something if I had thought of it. We won't wait until we get home to eat. There's a restaurant at the ferry-house. We'll have a good dinner there."

More than an hour passed before the three rose from their table. Another hour had gone by before they reached their headquarters. They were tired and sleepy. But their drowsiness vanished when Henry rushed into the living-room of their apartment and thrust a sheet of paper into Captain Hardy's hands.

"It's another message," he said, "and we deciphered it ourselves."

Captain Hardy stepped to the light and read the message aloud. "Five more transports sailed late this afternoon. All camouflaged."

"We know the man who sent that message," cried Willie. "We've been watching him all the afternoon, down on the hillside at Staten Island."

"But this message didn't come from Staten Island," said Henry. "The detector points straight east over Brooklyn, and the message was sent from a long way off. It was very faint."

CHAPTER VIII

WHERE MONEY TALKED

For a full minute the members of the wireless patrol stared at one another in speechless amazement. Then Willie broke the silence.

"I don't care where it came from," he said. "I just know that the man we were watching sent it."

"But how could he have sent it, when the wireless pointed to Brooklyn?" demanded Henry.

"Oh! I don't mean that he actually sent it with his own fingers," said Willie. "But we saw him watching the ships and there isn't any other place in the whole harbor where you can get such a good view of them. I just know he had something to do with that message."

"I'll bet the Germans have got a string of wireless outfits and that what he does is to stay in that house and spy on ships that pass through the Narrows and then telephone to one of these secret wireless stations," said the nimble-witted Roy. "And if that's the case he hasn't any wireless at all himself."

"If Roy is right," said Henry, "it's a pretty clever scheme. The secret service could take his house to pieces and not find a wire in it. Yet he's the man that's sending the messages, or at least starting them."

"Roy is doubtless correct," said their leader. "We know they have at least three stations and they may have many more. The object of that, of course, is to baffle any wireless man who may be on their track. If we hadn't stumbled on this spy post at Staten Island, we should have been completely blocked ourselves. But we've got something definite to work on now. We've got a definite clue. And sooner or later we will uncover some of their hidden stations. From now on we've got to watch this man on Staten Island as well as listen for messages. I don't see how we are to do it unless we send for more of the boys or move to Staten Island."

When the matter was laid before Chief Flynn he said no more boys were needed. Too many boys in one house would attract attention. So he arranged to transfer the wireless patrol to Staten Island. Living on the slope above the suspected house was a well-to-do but childless couple with a rather large house, who were warm friends of the Chief's; and they readily agreed, as a matter of service to their country, to take the wireless patrol into their home. So a wireless outfit was installed, with a concealed aerial, and the boys found themselves situated even more pleasantly than they had been before.

And it was well that they were pleasantly situated, for though their task was not difficult in one sense, in another it was extremely trying. Six hours a day each boy sat at the wireless listening in. Had it been possible to tune to longer wave lengths and pick up the interesting news with which the air was fairly alive, the task would have been anything but irksome. But to sit hour after hour with their instruments tuned to the short wave lengths used by the German agents and hear nothing, was trying enough. The watch on the spy's nest proved hardly less tedious. From a gable-window in the attic a very fair view could be had of the little house below. Here, on rainy days, a watcher sat during all the hours of daylight; and on other days the sheltering pines hid an observer. But day followed day, night succeeded night, and no message was registered on the wireless instrument nor did anything suspicious occur in the house under surveillance.

Indeed the fact that nothing did occur was in itself suspicious. For there was hardly a sign of life about the house. No man left it in the morning bound for business. No woman emerged from its door to go shopping of an afternoon. For days at a time nobody entered or left the place, excepting the grocer's boy who came with food.

Then one day a motor-car, with its top raised, chugged up the highway and climbed the steep driveway to the house on the cliff. Henry was in the attic gable on watch and he promptly notified his comrades. There was a rush for the third story, and four heads crowded close together as four pairs of eyes sought to identify the make and number of the car. But the name-plate was missing, and the license tag was so dusty that the number could not be read.

"Run down to the pines with this, quick," said Captain Hardy, thrusting his field-glasses into Willie's hand, "and get the number of that car. See if you can tell what make it is and look for distinguishing marks."

Willie scrambled down the slope through the concealing shrubbery and approached the house as near as he dared. But he had hardly reached his station when the driver ran down the steps of the house, sprang to the wheel, and was off at a fast pace. Willie climbed cautiously back to headquarters.

"Did you get its number?" asked his chief.

"No," replied Willie. "It was covered with dust. And I couldn't tell what make of car it was. But I saw the driver and I am sure I have seen him before and the car, too."

"That's not unlikely," said Captain Hardy, "if he lives anywhere near here. We've been here several days now."

"I'm sure I've seen that man somewhere," said Willie. "I wish I could remember where it was."

Another day passed and another, and still the little house on the cliff showed no signs of life. But one afternoon the monotonous watch came to a sudden end. Lew, in the attic gable, espied a fleet of transports coming down the bay. Instantly he spread the alarm.

"You boys slip down to the pines," said Captain Hardy to Willie and Roy. "If any one comes out of the house trail him. Now we'll find out whether this spy—if he be a spy—telephones his news or sends it out by messenger. The Chief has had the telephone wires tapped and is receiving a record of all conversations."

Lew continued his watch aloft. Henry sat tense at the wireless, waiting to catch any possible message, and Roy and Willie scrambled cautiously down to their favorite observation post in the pines. On came the transports, riding the waves in a stately column; yet the little house seemed as lifeless as ever.

"Watch close," whispered Willie. "Don't let anything escape us."

On came the ships, nearer and nearer, throwing the white spray away from their bows. They passed Robbin's Reef light. They drew close to the entrance to the Narrows. Breathlessly the boys awaited their nearer approach. The transports reached the narrowest part of the passage and still there was no sign of life in the little house. Willie gave a sigh of disappointment and started to speak; but before he could utter a word there was a movement in the window before them and the man they had previously seen appeared for a moment sweeping the Narrows with his glasses. Then he disappeared from sight.

"It's him!" exclaimed Willie, forgetting his grammar in his excitement. "Now he's either telephoning his message or getting it ready for a messenger. We'll soon know."

They had not long to wait. A figure was seen coming up the highway.

"It's only the grocer's boy," said Willie in disappointment. "This is the time he usually comes."

"I wonder if we aren't on a wild-goose chase," said Roy. "Maybe the man in that house isn't any spy at all. I begin to think so."

"I don't," maintained Willie. "I just know he's a spy, but how he sends his messages I can't figure out."

Just then the grocer's boy came out of the house. "There's no use trailing him," said Roy. "We already know who he is. While we're following him the messenger might come—if there is one."

"Captain Hardy said we should follow any one who left the house," said Willie, "so I suppose we'll have to watch this errand boy. You go this time, Roy."

In a minute Roy had reached the higher thoroughfare. He ran down the road at top speed and got to the grocery store before the loitering errand boy even came up into this higher road from the lower thoroughfare. But instead of entering the store, Roy turned the corner, retracing his steps in time to enter the store half a minute before the errand boy got there.

The grocer was behind the counter. "Have you any crackers?" asked Roy.

The grocer took down a package of Uneeda biscuits.

"You don't have any loose ones?" asked Roy.

"No, these are all we keep."

"Guess I'll have to take 'em," said Roy. "Got any candy?"

"In the case there," was the answer.

Roy walked over to the show-case and began to examine the stock. Just then the errand boy came in.

"Here's the money for the sugar," he said, handing the grocer a silver dollar.

The grocer took the coin and carelessly dropped it into his pocket.

Roy continued his inspection of the stock of sweetmeats. "Give me five cents' worth of gum-drops," he said.

The grocer began to weigh them out. A tall man with gauntlets and with motor goggles on his forehead came in.

"Hello, Fritz," he said jovially. "Got that sugar for me yet?"

"Just sold my last ounce," said the grocer. "I haven't been able to get a bit for three days."

"Himmel!" said the customer. "How much longer have I got to go without sugar in my coffee?"

He turned to go.

"Hello!" called the grocer. "Here's that dollar I owe you."

The man turned back, and the grocer pulled the coin from his pocket and dropped it into the man's gloved hand.

"Good luck to you," he said, then finished weighing out the gum-drops for Roy, and dropped the nickel in his cash drawer.

Slowly Roy retraced his steps. "Well, what happened?" asked Willie, as Roy rejoined him.

"Nothing," said Roy in disgust. "The errand boy came in and handed the grocer a dollar that he had collected for sugar. Pretty soon an automobile driver came in to get some sugar and the grocer said he hadn't any more, but he paid him a dollar he owed him."

Willie was silent, turning the matter over in his mind. "Then what?" he asked after a time.

"Nothing, except that I bought some candy and the grocer put the money in his cash drawer. Then I left."

"Where else would he put it?" asked Willie, abstractedly, as he tried to read some meaning into the grocer's apparently meaningless acts.

"Well," said Roy, "he didn't put the dollar the errand boy gave him into the drawer. He dropped that into his pocket."

"Why, that's exactly what happened when I was in there the other day," said Willie in surprise.

The daylight waned. Dusk came on. It grew too dark to see the spy's house from the pines. It was past time to relieve Henry at the wireless. The two scouts climbed to their own house for orders. As they came up the stairs they heard the voice of Henry.

"Come quick," he called. "I've got another message."

Everybody rushed to Henry's side. Captain Hardy seized the sheet of paper from Henry's hand, and counted the long string of letters written on it. Quickly he rearranged them in four equal lines. Then slowly he read the cipher. "Another transport fleet assembling. First five boats went to sea this afternoon."

"Where did this message come from?" he demanded, as he laid down the paper.

"From some point down the Jersey coast," said Henry, "and probably not more than twenty miles away."

A long silence followed. "We're simply up against it," said Lew dejectedly. "We don't get anywhere."

Suddenly Willie jumped to his feet with a cry. "I've got it! I've got it!" he almost shouted. "Why didn't I see it before?"

"Got what?" asked Roy, astonished.

Willie paid no attention to his question. "What sort of a looking man was that motorist?" he cried.

"A tall fellow, with black hair and with a big scar on his cheek," said the astonished Roy.

"I knew it," cried Willie. "I knew it! Now I know how the messages are carried. It's as plain as can be."

His fellows clustered about him. "What do you mean?" said Captain Hardy eagerly. "Explain."

"Well," said Willie, "when I followed that grocer's boy the other day, I saw him give the grocer a dollar which he said he had collected for sugar. The grocer put it in his pocket. But when I gave him money for candy he dropped it in his till. Just after I left the store and turned the corner a man drove up in a motor. I noticed him because he turned his car completely around and stopped at the curb. He got out and left his engine running. When I crossed the street to meet you, after you whistled, I dodged a motor-car. It was the same car, but I thought nothing of it." He paused, as though collecting his thoughts.

"Go on," said their leader eagerly.

"To-day," resumed Willie, "Roy followed that same grocer's boy from the house on the cliff to the grocery store and saw him give the grocer a dollar, which he said he had collected for sugar. The grocer dropped the coin in his pocket, but he put Roy's nickel in his drawer. A minute later an automobile driver came in. The grocer said he owed him a dollar and gave him the coin from his pocket. That driver was the same one I saw the other day."

"How do you know?" interrupted Captain Hardy. "You didn't see him to-day?"

"But Roy saw him. He's a tall man with black hair and with a scar on his left cheek. That's the man I saw, and it's the man who drove up to the house on the cliff the other day. I knew that I had seen him, but I couldn't remember just where." For a moment he stood silent, fairly panting with excitement.

"Well?" said Lew. "What about him? The grocer could owe him a dollar as well as anybody."

"But he didn't owe him a dollar," cried Willie. "Don't you see? The spy in the house below gave that dollar to the errand boy. He gave it to the grocer. He gave it to the motor driver. It's the same dollar. He didn't put it in the till with the other coins. He kept it in his pocket separate. That automobile driver is the man who carried the messages to the wireless. The messages are on the dollars."

CHAPTER IX

A FRESH START

Amazed, the members of the little patrol looked at one another silently.

"How could they send a message on a dollar?" demanded Lew at last. "They'd have to engrave it, and then they'd never dare to use the dollar again. Besides, it would be too dangerous. If the message were on paper, the paper could be burned or chewed up and swallowed, and the evidence of crime destroyed. But they couldn't erase the engraving on a dollar."

"I don't know how they do it," said Willie, "but I'm sure they write their messages on those dollars."

"Willie is doubtless right," said Captain Hardy. "We don't know how they do it, but the evidence leads directly to the conclusion Willie has come to. The spy in the house below us writes his messages on dollars and sends them through this grocer's boy and the motor-car driver to the various secret wireless plants the Germans evidently possess near New York. I think that is plain. And it indicates new lines of action for us. We must not only continue to listen in for messages and watch this spy's nest, but we shall have to follow this motor-car driver and also learn the secret of the dollars."

"Hurrah!" cried Roy, his eyes shining. "Now there'll be something doing." Then he struck a tragic attitude and declaimed, "Little do the treacherous hawks in yonder nest realize that the eagles of the law are about to swoop down on them."

"Some orator, Roy," said Lew. "If we're eagles, we must have wings. Are mine sprouting yet?" And he turned his back to Roy for the latter's examination.

When the laughter ceased, their leader went on, "You boys are to be congratulated for your discovery. You have accomplished a great deal. But what has been done is little compared with what remains to be done. And so far you have worked in safety. The work ahead may be very dangerous. The hidden wireless stations we are after are probably in lonely places. The men operating them are desperate fellows and will not hesitate even to commit murder. If one of you boys should follow this motor driver into a lonesome spot and then be caught, you might never return."

The smiles faded from the faces before him. But the grave looks that succeeded were not expressions of fear. Rather they were looks of determination—the same set marks of grim purpose that Captain Hardy had seen on these same youthful faces when the wireless patrol was stalking the desperate dynamiters at the Elk City reservoir.

Again it was Roy who brought back the smiles. "If we have to follow that automobile driver," he said, "it's a question of 'where do we go from here, boys?'"

"Only the boy who does the following can answer that question," answered Captain Hardy. "But there are several matters that we can decide at once. I think that we've determined pretty definitely that the man in the house below us——"

"In the hawk's nest," interrupted Roy.

"Well, the man in the hawk's nest," continued their leader, smiling, "is a German spy, that he is there to report the movements of our transports, and that he does it by means of messages sent out on silver dollars. Now we've got to get hold of one of those dollars. That might not be a difficult task in itself. We could hold up the grocer's boy and take the dollar away from him, or we might get it away from him by trickery and substitute another dollar for the stolen one. We might even be able to pick the grocer's pocket and give him a substitute coin. But neither plan would help us because the trick would soon be discovered and the spies would know that they are suspected. It wouldn't do us any good to get their code if they knew we had it. They would simply use another. What we must do is to locate their agents, one after another, learn their codes and ciphers, and catch their messages in the air. When we have laid bare the entire scheme and learned who their agents are, then the secret service can grab the entire organization at once and end this treachery for good."

Captain Hardy paused and looked uneasily across the room, as though lost in thought. His companions were quiet as mice, each also busy with his own thoughts.

"It's a long, hard task, boys," said the captain, after a time, and he drew a deep breath, "a long task and, from now on, a dangerous task. Whatever you do, boys, remember the Chief's warning. Above all else, we must be careful not to alarm the men we are watching."

As Captain Hardy rose to get his hat he said, "I don't quite see how we are to follow this motor-car driver without being detected. So I am going over to Manhattan to see the agent the Chief has put in charge of this investigation. Perhaps I'll have some interesting news for you when I return. Meantime, keep your eyes and ears open and be careful."

With renewed interest and determination the members of the wireless patrol returned to their posts. But though they listened faithfully at the wireless and uninterruptedly watched the hawk's nest on the cliff below them, no alarming sound came out of the air and no suggestive movement occurred within their vision.

Their captain came back with a smile of satisfaction on his face. But the members of the wireless patrol were too well disciplined to question their leader. They knew that, as always before, he would give them the proper orders at the proper time; and that if they obeyed those orders faithfully and intelligently, success would follow. But Captain Hardy was different in many respects from other commanders, and his subordinates were not at all like ordinary privates in an army. There was no question as to their loyalty, discretion, or intelligence; and their leader believed he could attain the greatest success by taking them into his confidence. So presently he answered the question that each boy was longing to ask.

From his pocket he produced detailed maps of all the neighboring country, so mounted on cheese-cloth, after being cut into squares, that they could be folded into small size without injuring the maps themselves. Thus the bearer could always follow his route, whether he walked or rode, whether the air was calm or the wind blew fiercely, by carrying in his hand the necessary map folded in small compass.

Now Captain Hardy spread out his maps full length on a table, and for half an hour the little group bent over them, heads close together, examining the topography of the city's environs as once they had studied the city itself. Marked to show altitudes, roads, byways, rivers, streams, marshes, woodlands, and even the buildings themselves, these maps enabled the little group of scouts to see, through their imaginations, every foot of the country about New York.

They visualized the great, flat, low-lying stretches of southern Long Island and New Jersey; the abrupt bluffs of Long Island's northern coast by the shore of the Sound; the various watery arms that encircle the American metropolis, permitting ships to sail in every direction; the majestic Hudson leading straight north through a wonderful country of rocks and hills, the impressive Palisades flanking its western bank with their towering perpendicular walls of stone; and the rocky, rolling country lying west of them, interspersed with streams and swamps and woodlands and open fields and clustered villages. And when they had finished their study of the maps, they knew more about the topography of the country they had studied, its roads and paths and groves and elevations and other physical characteristics, than half the people who lived in the region. So they were prepared, if need be, to find their way about with little difficulty. And it was well they were so prepared. In the dangerous days to come they were to need all this knowledge.

When they had studied the maps to their hearts' content—and each of the four boys again and again examined them—Captain Hardy folded the maps and thrust them into a waterproof cover. They made a neat little packet like a thin book.

"You will be interested to learn what the secret service has found out," said Captain Hardy, as he stowed the maps in his pocket. "When I left here, I reported immediately to the man in charge of this particular investigation. Our discovery seems to me so important that I ventured to ask why the secret service men didn't take the case up themselves, as they would no doubt get along much faster than we possibly can. For it seems to me message sending ought to be stopped at once. The agent said that all this was true, but that the secret service was so crowded with work it had to take up the most important matters first."

"Most important matters!" cried Roy, in indignation. "Doesn't the secret service consider the guarding of our troops important?"

"Yes, Roy. But whether the Germans know exactly when our ships leave or not, their submarines will be waiting for them and our destroyers will always be guarding the transports. But here in New York German spies are trying to create riots, to blow up buildings, to burn factories. They destroyed almost a million bushels of wheat in one fire recently. So you see that the secret service first must watch the enemies that are trying to destroy our greatest city. Our secret service isn't one-quarter as large as it should be. That is the fault of Congress. But meantime it is doing wonderful work, and it is a great privilege to be able to assist in that work."

"But what have they found out about this job?" demanded Roy.

"You're like a hound on a keen scent, Roy," said their leader. "Nothing ever takes you away from your objective. Well, this is what they've found. It seems that they have been keeping a record of the grocer's telephone messages, as well as those from the 'hawk's nest' down below. Every time transports sail, some one in Hoboken calls up this grocer and says, 'I have some sugar on the way. Do you want any?' And the grocer replies, 'Yes. How many barrels can you let me have?' And the man in Hoboken gives the number. That number corresponds with the number of transports about to sail. So you see how the grocer knows when to send his boy for the wireless messages. But before he sends him, he always telephones to the 'hawk's nest' and says, 'I have some sugar coming and can let you have five pounds to-day. Do you want it?' And the number of pounds he offers is the same as the number of ships that are to sail. So the spy below us knows what to look for. And I suppose the man in Hoboken also telephones the automobile driver when to come for the dollars."

"Who is this man in Hoboken that does the telephoning?" demanded Roy, when Captain Hardy had done speaking.

"Ah! That they don't know. He has always called up from a different place and has gotten away before the secret service could spot him. But the agent assures me that they'll have him soon. He always telephones from a station close to the piers where the transports load. The next time he calls for the grocer, the telephone operator is going to delay him while she notifies a secret service agent posted near by with a motor-cycle. So they'll spot him and trail him.

"And that reminds me," continued Captain Hardy, after a pause, "that we're to do a little motor-cycle work ourselves, and that Henry has been selected for the job because he is familiar with motor-cycles."

Henry's eyes lighted with pleasure. Not only was he the oldest boy in the wireless patrol, and Captain Hardy's first lieutenant, but he was one of those natural mechanics who seem to know instinctively how to handle tools and make things. Indeed he had constructed his own wireless outfit and shown his fellows how to make theirs; and he could repair a motor-cycle almost as skilfully as a garage man. So it was natural that he should be selected for this task.

But there was still another reason why his captain had chosen him for the work he had in mind. Though not so quick or clever as Roy, Henry was a keen observer and close reasoner. Moreover, he was entirely dependable, was very discreet, and being the largest boy in the party, was best fitted to take care of himself if he got into trouble.

"We are going to trail this automobile driver with a motor-cycle, as you have probably guessed," explained Captain Hardy to the little group of scouts. "And Henry is to do the trailing. Come, Henry. We'll go take a look at your machine. The secret service people said that it would be here in half an hour."

"Where? In this house?" asked Roy eagerly.

"No, not here, but at a house around the corner from the grocer's. It will always be in readiness for instant use."

As Henry put on his hat and followed his leader, the other scouts looked at him somewhat enviously. "Remember," said their leader, turning about, "each one of you has his work to do, just as Henry has. See that you do it."

At once the boys returned to their posts, while Henry and his captain passed out of the house and went down the street. Instead of going directly to their destination, the two made their way by a roundabout route and kept a sharp lookout lest they should meet the grocer or his boy. But they passed almost no one and came soon to a little white house, not far from the grocer's store, that was set back in a yard behind a high hedge. Connected with the house was a small garage, built so as to resemble an extension of the dwelling.

A keen-eyed woman answered their knock at the door and looked at them questioningly.

"We are the sugar refiners sent by the Federal Sugar Company," said Captain Hardy, repeating the words given him by the secret service agent.

"I've been looking for you," replied the woman. "Come in." And she led them at once through the house to the garage.

Henry was about to ask Captain Hardy what he meant by saying that they were sugar refiners, but when he saw the motor-cycle that awaited him he forgot his question and gave a sharp cry of exultation. It was a beautiful machine, with tires so strong and thick they were practically puncture proof and were evidently equal to any demand that was likely to be made upon them. Evidently the engine was one of great power. The frame of the machine was a dark gray; and Henry instantly noted the fact that there was an almost utter absence of nickel about the motorcycle. The spokes, handle-bars, and trimmings were all enameled black. The headlight was a powerful electric one, with a black cap over the lens. With great interest Henry examined the spark- and gasoline-controls, the motor itself, and finally the muffler, which was of the most improved variety. He looked in the gasoline-tank and found it full. The oil-tank was brimming. Every moving part had been carefully greased and cleaned.

"What's this?" cried Henry, of a sudden, noting what seemed to be an extra and unnecessary piece of framework.

"Take it out and see," said Captain Hardy, with a smile.

Carefully Henry examined the fastenings, to see how the extra tubing was adjusted. Then he drew it forth.

"A metal cane," he said, puzzled. "What is it? What is it for?"

Captain Hardy explained. Then he picked up a small electric torch, some well insulated wires that lay coiled on a near-by chair, and something that looked like a giant fountain pen. He handed these articles to Henry, and repeated what the secret service man had told him as to their use.

"Put them in your pocket and be very careful that you do not lose them," directed Captain Hardy. "Carry them with you so that you can run to your motor-cycle at a second's notice. Now replace that cane on the machine."

Henry slid the cane back and fastened it in place. It was gray, like the car, and seemed to be a part of it. Then Captain Hardy fastened the little map case above the gasoline-tank in such a way that Henry could pluck out a map as he rode.

"Now," he said, "there is nothing to do but wait until the automobile driver comes for another dollar. Then you must follow him wherever he goes. You must watch every movement he makes. But you must not let him see you. It's a hard thing to ask of you, Henry, for everything hinges upon your success."

A look of determination flashed in Henry's eyes. "I'll do my best," he said simply.

"I know you will," rejoined his leader. Then he added, with a smile, "Now we'll go back to the eagle's nest and wait for the hawk to appear."

CHAPTER X

THE PURSUIT IN THE DARK

Day followed day but that bird of prey did not appear. "A watched pot never boils," said Henry at last, trying to conquer his impatience; and he turned his mind from the task of following the automobile driver to the even more difficult task of securing one of the dollars. For sooner or later the wireless patrol would have to procure one of these mysterious coins. But Henry could see no way to accomplish that end without alarming the quarry. Day after day the little patrol discussed the question. It was useless to think of securing a coin from the man on the cliff, from the grocer's boy, or from the grocer himself; for none of the three had possession of the coins very long after they were marked. And what became of the coins after they left the grocer's hands could as yet be only guessed at.

Again and again, as the days passed, the members of the wireless patrol discussed the secret of the dollars, but nowhere could they find even the suggestion of a solution. Slowly time dragged on. Day followed day. The watch grew monotonous and tiresome. There were no signs of hostile activity in the hawk's nest and the secret service had no suspicious telephone conversations to report. It required all their resolution to keep the young scouts at their task of listening in. They even began to think that they had been detected and that the activities of the spy in the hawk's nest were ended.

Then, one afternoon, galvanizing them to sudden action, came a cryptic message from the secret service, announcing that the Federal Sugar Company could use experienced refiners at once. Henry took the message, and recalling what Captain Hardy had told the woman when they went to see the motor-cycle, at once guessed its meaning. He ran to Captain Hardy and repeated it.

"You guessed rightly," said Captain Hardy. "Hereafter we, too, have to use code messages, and we just carried out the spy idea about sugar. This message is to warn us that transports are sailing. Go to your stations, boys."

Lew flew back to the wireless. Roy and Willie hustled down to the pine grove. Henry, his heart beating fast, hurried away to his motorcycle station.

For a long, long time nothing happened. Then a line of transports came into view. Presently the spy appeared at his window, sweeping the channel with his powerful glasses. For several moments he studied the passing ships carefully, then withdrew from the window and was lost to sight. In a very few moments the scouts saw the grocer's boy, with his basket and a few small packages, enter the house, then hurry away. Roy trailed him directly to the grocery store, but did not enter.

Henry, meantime, impatient, like Paul Revere, "to mount and ride," stood peering out of a tiny window of the garage, awaiting the expected motor-car. In his eagerness minutes seemed like hours. As time passed and no motorcar came, he began to believe that none would come, that the spies had learned of the trap set for them, and that they had discontinued their work or devised some new plan of operation. So impatient did Henry become that he could hardly refrain from running into the street to see if any motor-cars were approaching. At last his anxiety was relieved. He heard the regular beating of a motor climbing the hill. Then as he glued his eye to the tiny window the familiar car, a powerful roadster, with its top raised, rolled by. Again Henry tried to catch the number and failed. Then he knew that the dust-covered license number was not dust covered by accident. Quickly he noted the treads of the tires, and the shape of the wheel hubs, axles, and springs, so that he could identify the car. Then it passed from his sight.

And now his anxiety suddenly grew a hundredfold. Always before, the car had returned the way it came. Suppose that this time it should go back by another route and he should miss it. He could not endure the thought. Quickly he opened the door and peered forth. The driver was just turning his car, as he had always done before. The matter was settled. He would pass Henry's hiding place on his return. Quickly Henry shut the door and waited with what patience he could command.

for what seemed like an hour he waited. His pulse beat fast with excitement. He could hardly compel himself to stand quietly by his window and wait. The old fear that the motorist had gone away by some other route returned and began to torture him. He wanted to run out into the street and assure himself that the car was still in sight. And then, when it seemed he could endure the suspense not a second longer, he heard the purring of a motor, and the car he was waiting for slid quietly by and began to descend the hill toward the ferry.

At once a new fear sprang up in Henry's heart. Suppose the motor-cycle wouldn't go. Suppose he should be so slow as to miss the ferry-boat. Desperately he flung open the door and trundled his motor-cycle out to the street. The roadster was only a block ahead of him. Speedily Henry pushed the cycle along the road. The motor began to bark and Henry leaped to the saddle. In another instant he was speeding after the roadster and was already so near it that he had to jam on his brake to avoid coming up to it. Near the ferry there was more traffic and Henry felt relieved. He dropped back a little distance and was almost completely hidden from the roadster by the carts and cars between them. So they proceeded to the ferry, the suspected driver bringing his roadster to a halt near the front of the ferry-boat just as Henry, following a string of wagons and carts, reached the other end of the craft. Then the whistle blew and the boat pulled out into the Bay.

But Henry had now no eyes for the sights in the harbor that had formerly so fascinated him. His entire attention was centred on the roadster. The driver of the roadster remained in his seat, calmly looking out over the Bay. Henry stood his machine against a post and sought a position near by where he was sheltered from the spy's observation by a huge coal truck, but where he could himself distinctly see the roadster by peering through the spokes of the truck wheels. Again he made a mental inventory of the distinguishing features of the car he was following. And before the ferry-boat reached Manhattan he could have passed a perfect examination as to the appearance of the roadster.

It was already dusk when the boat slid into its slip, and the heavy clouds overhead gave promise of a dark night. Henry was thankful. Up Broadway he followed the roadster at a safe distance, then up Park Row, and so to the Brooklyn Bridge. Across this magic structure, one hundred and fifty feet above the surface of the water, Henry continued to follow the roadster. The great buildings, piled skyward in huge masses, were twinkling with a million lights. Boats were coming and going on the stream below. Electric cars followed one another across the bridge in endless procession. Elevated railway trains thundered past unceasingly. Up-stream shone the fairy lights of the other bridges that span the East River. The Navy Yard lay in full view. But the scene that at other times Henry would have found entrancing, now he scarcely noticed. He had eyes for one thing only—the rolling motor-car ahead of him and the red eye that now glowed at its rear.

He turned on his light and at a safe distance followed the roadster, which was heading due east. They passed the business portions of Brooklyn. They left Prospect Park behind them. They traversed a region of apartment-houses. Then came less thickly settled districts, with block after block of private residences, each in its own little yard. And so they proceeded to the very outskirts of the city, where houses gave place to vacant lots and vacant lots were succeeded by open fields. Darkness had come. Traffic had grown less and less. Now there were no sheltering vehicles between himself and the roadster. A great fear of discovery sprang up in Henry's heart. He switched off his light, risking arrest, and rode on in the darkness. Occasionally he passed under a lone street lamp. And now he understood why his machine was enameled black instead of being nickel finished. It gave back no answering gleam when beams of light fell upon it. It was made for just the secret sort of work it was doing now. For, with his motor completely muffled, his lamp extinguished, Henry was now riding through the night like a dark shadow.

Long before this, Henry had slipped the proper map from its case and had followed his route as far as he was able to see. Though his eyes could no longer pierce the darkness, Henry knew that he was passing through a lonely, undeveloped section of land. Dimly he glimpsed tiny bits of woodland here and there. The lonely lights Henry occasionally saw were the lamps in isolated farmhouses. He could no longer tell exactly where he was, though he knew the road he was following. But he had watched his speedometer closely and he knew he was traveling about twenty miles an hour. He was keeping pace with the motor-car, but riding several hundred yards behind it. So they continued for a long time.

Suddenly the motor-car swung round a curve and vanished from sight. Henry knew the car had rounded a curve because he saw the lights swing. A minute later as he was about to reach the curve himself, he heard the rapid beating of hoofs and a team of horses came tearing round the bend and charged straight at him. Evidently the driver had lost control of them and it flashed into Henry's mind that they had been frightened by the roadster ahead. But he had no time to think of anything. The frantic animals bore down on him like an express-train. Quick as thought Henry turned sharply to the right and threw on his power. The horses were almost upon him. The driver glimpsed him, cursed him savagely for having no light, and gave a powerful heave on the reins. The horses swerved in one direction as Henry shot in the other, missing them by less than a foot. Before he could straighten his machine again, it had left the road and was plunging over the rough surface of a field.

Henry jammed his brake on so suddenly that it toppled him from the saddle, but neither he nor the machine was injured. He turned the motor-cycle about and headed for the road. And now his hair almost stood on end. In the darkness he could dimly see some great lumber piles, as large as houses. He had all but crashed into them at high speed. Now he understood why the roadster's light had disappeared when the car turned the curve. It had been hidden by these great lumber piles. Rapidly Henry ran back to the road. He knew the motor-car would now be far ahead of him. He should have to hasten to overtake it. He ran along the highway, pushing his machine, and leaped to the saddle when the engine began to explode regularly. Then he turned the curve and peered ahead into the darkness. The road seemed to lie straight before him, but the motor-car had utterly vanished.

For a moment Henry rode on, almost bewildered. Then he looked rapidly about him. No farmhouse was in sight to which the motorcar might have gone. No light gleamed anywhere. But he could dimly see trees here and there. And he made out a wooden fence lining the left side of the road.

"Lucky I didn't shoot in that direction when I met that team," muttered Henry. "I'd have gone clear through that fence." He dismounted, set his machine up, and took out his pocket torch. Holding it close to the road, he began to examine the highway. "There are the marks of his rear tires," he muttered.

And thankful indeed was the puzzled scout that he had learned so well at Camp Brady to observe carefully. He mounted his wheel and rode a few hundred yards further. Then he examined the road again. He found the tracks he was searching for. He rode on and dismounting, found in two places the telltale marks. But the third time he examined the highway there were no marks of the roadster's tires visible.

"He left the road between this point and the last stop," murmured Henry.

He went back a hundred feet and searched. There were no tire marks. Another hundred feet showed no prints in the dust. But the third hundred revealed the wheel marks. "Ah!" said Henry, "he turned off close by."

He set his wheel against the fence and went forward, following the prints with his light, which he shaded carefully and held close to the road. Within fifty feet the marks turned straight off to the left. The car had passed from the highway through a gap in the fence, into an open field. What the field was like Henry could only conjecture. He dared not flash his light around to see.

He ran back and got his machine, then followed the wheel prints into the field. They did not show readily on the grassy surface, and soon he had lost them altogether. At first a sense of fear clutched at his heart. He recalled his leader's words as to the dangerous nature of this duty. Here he was in exactly the lonely situation his captain had foreseen, by himself, and with no means of defense. The enemy he was trailing had disappeared. He might be a mile distant or he might be waiting for his pursuer, behind the nearest tree. Henry shivered with fear and stood irresolute. But the feeling passed when he realized that he had lost the trail, that his quarry had escaped him, that he had failed his captain. A wave of remorse swept over him. The sense of fear left him entirely, and he bent all his energies to the task of finding the motor-car. He hid his wheel in a thicket that he might work faster, pausing only to snatch from it the metal cane fastened to the frame.

Cautiously he glided forward, crouching as he moved, and taking advantage of every rock and bush he could see to screen himself. He held his breath and listened. Now he crept forward a foot at a time. Now he advanced swiftly for yards. He worked his way to the right and the left. But nowhere could he see what he was searching for, and no betraying sound came out of the thick blackness.

"It's no use," he said to himself bitterly, after he had searched for a quarter of an hour. "I have lost him, and if I am not careful I'll lose his message as well."

Near by he could dimly discern a tall stump. He ran over to it and on it laid his map, a pencil, his electric torch, his knife, the wires that he had been carrying in his pocket, and the giant fountain pen. Grasping the tip of his cane he gave a sharp tug and an inner lining slid outward. From this he drew out a third length, and from that a fourth. His metal cane was in reality an extension rod, not unlike a telescoping fishing-rod. It was fully ten feet long. In its curved handle was a small opening, like a keyhole. Into this Henry jammed the bayonet connection that terminated one of the wires. The other end of the wire he thrust into a like opening in the side of his big fountain pen. Into the opposite side of his pen he fastened one end of his second wire, attaching the other end of this wire to his knife, which he thrust deep into the earth. Then, raising the extended cane aloft with his left hand, he put the point of his fountain pen to his right ear and listened. The mysterious articles that the secret service had supplied constituted a complete wireless receiving set. He could catch any message sent from a point within six or eight miles.

He was not a moment too soon. Hardly had he gotten the fountain pen adjusted before there came a crackling in his ear. He rested his cane, upright, against the stump, and began to tune his instrument by sliding the cap of the fountain pen in and out. In a second he had tuned it perfectly. The sounds came to him with startling clearness.

"He's near at hand," muttered Henry.

He seized his pencil and wrote down on his map the letters that were sounding in his ear. Then with frantic haste he disconnected his instrument, telescoped his extension cane, and gathered up the different articles and thrust them into his pockets. As rapidly as he could pick his way, he went back to his hidden machine. He fastened the metal cane in place, and got everything ready for a quick start.

Suddenly a faint purring noise came to his ears. "Ah!" muttered Henry, "he's started his motor. He's off in that direction. What shall I do?"

His first impulse was to run at speed toward the purring motor, and to try to locate exactly the position of the hidden wireless station. But discretion showed him that was not wise. The spy might turn his lights on at any moment and Henry would be caught. Then everything was lost.

"I must make sure I can find the place in the daytime," muttered Henry. Carefully he gauged the sound, deciding whence it came. "He's right off there," he said. And with his heel he made a long mark in the turf, pointing straight toward the sound.

Almost before he finished, the sound grew louder and Henry knew the car was advancing. He shrank back into the thicket, dragging his motor-cycle with him. An instant later the roadster rolled softly past, not more than fifty feet distant. In a moment more the car had reached the fence and turned into the highway. Its lights suddenly flashed out and the car went bowling down the road toward Brooklyn.

Henry leaped from the thicket and ran toward the highway, pushing his motor-cycle before him. He paused at the opening in the fence, and with his knife smoothed a space on one of the posts and marked a cross on it with his pencil. Then he ran to the highway, started his motor, and was soon flying down the road in pursuit of the roadster. And as he had come, so he returned, with lights out, until Brooklyn was reached and the streets were once more alive with traffic.

At a safe distance he followed the unsuspecting motorist and saw him turn into a private yard in Flatbush. Instantly Henry dismounted, thrust his wheel behind a hedge that fenced a private residence, and gained a position where he could watch the spy's house. He saw the spy close and lock his garage and enter the house. Stealthily Henry approached and noted the house number. At the corner he got the name of the street. Then he hurried back to his hidden motor-cycle and was soon flying back to his comrades at the eagle's nest.

CHAPTER XI

AN UNSUCCESSFUL SEARCH

It was characteristic of Henry that he should tell the worst about himself first. In his own manly way he was willing to accept the blame for his failure.

"He got away from me," he began, so chagrined that he could hardly repress the tears. "I didn't find the hidden wireless and I have failed in my task."

Before his captain he stood with downcast eyes and tortured heart. His experience at Camp Brady had taught him that the wireless patrol expected every member to do his duty—and he had failed.

Captain Hardy looked at his lieutenant for a moment without answering. He had not the slightest idea of what had occurred, but he recognized instantly the manliness of Henry's report. The latter was offering no excuses, making no attempt to shield himself from the consequences of his failure.

"Suppose you tell us just what happened," said the leader gently, "and we can judge better how badly you have failed."

Gratefully Henry looked up. He had not expected a scolding. That was not Captain Hardy's way of disciplining his boys. But he had felt sure his leader would show how deeply he was disappointed, for Captain Hardy was terribly in earnest in this quest for spies. So once again Henry's heart went out to his captain. Rapidly he related what had befallen him. As he proceeded with his story, his leader's face lost its look of grave concern, his eyes began to flash with interest, his cheeks to burn with eagerness. When Henry's narrative had reached the point where the motor-car had disappeared in the field and Henry was searching for it. Captain Hardy held up his hand.

"Stop a moment," he interrupted. "You were in no wise to blame for what happened, and instead of being condemned for failure you are to be commended for your success. Many a boy would never have found where that car went. And even though you did not learn exactly where the car was, you have located the field and you may be sure that driver never went very far in a field. We shall find the place easily enough. Go on."

Henry looked at his leader gratefully and a happy light came into his eyes. "Do you really think I didn't fail?" he asked eagerly.

"Assuredly," insisted Captain Hardy. "I think that you have learned enough to enable us to locate this hidden station. Go on."

Henry proceeded with the story of his search in the dark, of his uncertainty as to what he should do, of his fear of missing the message as well as the car, and of how he had intercepted that message, marked the fence post, and located the home of the automobile driver.

"Why, Henry," cried Captain Hardy, when the recital was ended, "whatever put it into your head that you had failed? You have done well—exceedingly well."

"But I didn't find the hidden station, and you said that was so important."

"That is a mere detail, Henry. We shall find it easily enough. We have our experience at Elk City to direct us."

"That's just why I felt so bad," said Henry. "If these Germans have concealed their wireless plant as skilfully as the dynamiters did at Elk City, we may never find where it is."

"We'll try before we give up hope," said the captain smiling. "And even if we never find it, we now know something more important than the location of one of their several wireless plants. We know where another member of the gang lives. That is excellent, Henry, excellent! The Chief will be more than pleased. I know he is a great deal more concerned about this wireless situation than he permits us to think. The public is clamoring for protection for the troops and the Chief simply cannot accomplish one-fourth of what is demanded of him. If we uncover this gang for him, we shall do a very real service to America, boys."

"We'll do it," cried Willie vehemently. "We'll do it. We'll get 'em just as sure as we got the dynamiters."

"I believe we shall," smiled the captain. "And if that's the way you all feel about it, I know we shall. We're closing in on them fast. To-morrow we'll go out to that field Henry has marked and see what we can find in the daylight."

So it happened that the succeeding forenoon found the five members of the wireless patrol rolling rapidly toward the point of investigation, in a motor-car furnished by the secret service and driven by one of its agents. Henry sat beside the driver and pointed out the way, while the others crowded into the rear of the car.

With his map on his knees Henry traced the way. Speedily they passed through the built-up portion of Brooklyn and came shortly to the sparsely settled district through which their road ran. Henry scanned the way with curious interest. He had been over the road but he knew nothing of what he had passed. Occasionally they whirled by a tree close to the road that Henry thought he had glimpsed in the darkness. So they flew forward until Henry, looking eagerly ahead, cried out, "There are the lumber piles."

The driver slowed his car almost to a walk and they looked in the dust for telltale marks. Few teams had passed since Henry's adventure, and in the dust could still plainly be seen the marks of Henry's wheel as he had turned sharply into the field, and the narrow tracks of the vehicle that had almost run him down.

But Henry was more interested in marks of another sort. "There!" he cried suddenly. "See those tracks? They're the marks of the spy's roadster." And he pointed to parallel tread marks, one made by a chain tread tire and one by a diamond tread.

They passed on. Not many hundred yards distant was an opening in the fence. "That's the place he turned off," insisted Henry. "See that light place where I shaved the post?"

But they did not turn into the field. Instead the motor-car continued steadily on its way. A half mile up the highway was a road-house known to the driver.

"It's about eleven o'clock now," said the secret service man. "We'll have luncheon at the roadhouse and in the meantime we can stroll around and hunt up this wireless plant. We'd attract too much attention if we drove directly into the field."

They stopped at the road-house, ordered luncheon, and said they would stroll about until noon. Then they wandered, apparently aimlessly, about the place and into the fields. The country was nearly level, with slight depressions here and little hillocks there, and bits of woodland all about. The road-house was the only structure in sight, and when they had passed beyond a slight elevation, even this was hidden. Apparently there was not a soul in the neighborhood. They paused just inside a little grove and made sure that no one was following them from the road-house. Then they pushed rapidly on into the little thicket which Henry recognized as his hiding-place of the previous night.

After a moment's search, Henry found the mark he had made in the turf. "The motor-car was in that direction," he explained, pointing along his turf mark.

His fellows looked in the direction of his outstretched arm. At a distance of a quarter of a mile was a thick little grove. Henry was pointing straight at the heart of it.

The scouts had kept themselves well hidden in the thicket as Henry was finding his mark. If any one was in the wood, that person could not as yet see them.

"I have no doubt we shall find the secret station in that grove," said Captain Hardy. "I see several tall trees sticking up above the others that might conceal aerials. I doubt if any one is there now, but some one might be. So we shall have to approach carefully and in such a way that we can capture any one who might be within the grove. Suppose we advance on it from all four sides, as we did on the willow copse at the Elk City reservoir. Then if any one is within the grove we shall see him."

The leader gave each boy his orders and the advance began. Henry was to circle and enter the woods from the rear. Roy was to approach from one side and Willie from the other. Lew was to go in at the front. Captain Hardy and the secret service man were to station themselves outside the wood so that they could see every point of its exterior and detect any one leaving it. Each glided away toward his post.

At a given signal from Captain Hardy, the boys began to work their way silently from their posts into the grove. This was small in extent and such precautions seemed almost unnecessary. But after their desperate experience with the dynamiters, the members of the wireless patrol were taking no chances. They knew full well that discretion is the better part of valor. And they knew, in addition, that the success of their search might depend upon the caution with which they proceeded. So they went forward, when the captain's signal rang out, like so many Indians on the war-path, stalking a hated enemy.

Indeed they were almost as invisible as Indians. Each had circled skilfully to his post. And now each crept forward silently, slipping from rock to bush, taking advantage of the slightest cover, and advancing so stealthily through the tall grass that even the two men on watch outside the grove could hardly tell where the scouts were moving. And any one inside the grove could not have detected them at all.

The four scouts reached the four sides of the grove almost simultaneously. Each of the four crept round the trunk of a big tree and squatted down with the trunk at his back, to look and to listen. From side to side their eyes roved, examining every tree and stump in sight. But they saw nothing on the ground or in the branches overhead to alarm them. There was no indication of human presence other than their own; and Willie was certain that the wood was deserted, for several small flocks of birds flew up in alarm as he penetrated the grove. Had other men been within the wood, he knew the birds would long ago have been frightened away.

Slowly the four scouts worked their way toward the centre of the grove, gliding round the trunks of trees and stopping every few feet to look and listen. But they heard nothing, saw nothing, to indicate that any man was within the grove. Each one, as he advanced, scouted to right and left of his line of march, so that when the four met in the centre of the wood, they had covered every rod of ground within the grove. And they had found nobody.

What was more, they had seen no signs of a wireless outfit. But, in view of their experience in searching for the dynamiters' hidden wireless, this was not surprising. None of the scouts had expected to find the secret plant without a thorough search. As soon as Captain Hardy and the secret service man joined them, a systematic search of the wood was begun.

There could not have been more than two hundred trees in the little grove. Satisfied that the place contained no enemy agents, Captain Hardy took his company to one end of the ground and began a careful examination of each tree. The six searchers strung out in a line across the grove, testing each tree as they advanced. They scanned the trunks and thumped them with clubs to make sure that they were not hollow. They peered at them from all sides, looking for holes and hollow limbs. With sticks they scratched away the leaves from about the bases of the trees, turning up the soil for several inches and testing it for hidden wires. All the trees seemed sound. No hollow limbs were discovered. No suspicious marks were found in the earth about the tree trunks. The tall trees noted by Captain Hardy seemed never to have been touched by man. From tree to tree the search proceeded until every tree in the grove had been tested and the scouts were on the far edge of the wood. But no hidden wire, no secret instruments, no skilfully concealed aerials were found.

Blankly the searchers looked at one another. "It must be here," said Henry. "I am absolutely certain that the motor-car came from this direction and was about this distance from where I stood. And the signals were so loud and clear that I'm just sure they were sent from some spot close by."

"Let us look for wheel tracks," suggested Captain Hardy. "If we can find where the car stopped, we shall know that the message was sent from some point near by. Search along the sides of the grove first."

The party divided, and three searchers examined the ground along each side of the grove. Walking abreast and several feet distant from one another, they covered a broad strip of ground. Twice each party retraced its tracks but found nothing.

"Try another strip, farther away from the grove," said Captain Hardy.

Again the searchers lined up and went slowly forward on either side of the woods. Bending low, stepping slowly, sometimes kneeling to examine a suspicious mark, they moved carefully on. The thick turf had taken no telltale imprint.

"I fear it's useless," sighed the leader.

"Let's try again," pleaded Willie. "The car was here. We know that. And somewhere it was bound to make a mark. It might have gone beyond the grove."

They made another search, this time extending their examination to the land beyond the wood. Suddenly Roy gave a cry. "Here it is," he called.

The others ran to him. And there, sure enough, in a little bare spot between two hummocks of grass, was the plain imprint of a diamond tread. Instantly Roy and Willie dropped to their knees and began to feel along the line of the tire mark.

Henry and Lew, meantime, searched to right and left of them. "Here's his other wheel track," suddenly cried Lew, and there, sure enough, was a distinct impression of a chain tread tire.

They proceeded in the direction in which the car had been moving. "Here's where he turned," cried Henry.

The turf before him was torn and ragged. Distinctly they could see the impression made by the driving wheels as they gripped the ground in starting.

"Then here is where he stood," said Captain Hardy. "It is immediately behind the wood. Your mark pointed straight enough, Henry, but your man was farther away than you thought. Probably he ran behind this grove to make doubly sure he would not be seen from the highway. The hidden station must be in this end of the grove. We'll search again."

Once more they plunged into the wood. Again they examined every tree. Up one trunk after another shinned Roy and Lew, who were born climbers. But hunt as they would, search as they might, they found nothing to indicate a secret wireless. At last, completely baffled, they gave up the search.

"It's here," insisted Captain Hardy. "Our experience at the Elk City reservoir makes me sure of that. They're too clever for us. But we'll get them yet. We'll follow that roadster so closely next time that we can't miss the secret. It's too bad, boys, but don't be discouraged. We have done much to come so close. Now we'll go back to the road-house. It's long past time for luncheon."

CHAPTER XII

ANOTHER OBSTACLE

Time wore on. Now that there was something definite to work on, the secret service began to take a more active part in the spy hunt.

"You have helped us greatly," said the Chief to Captain Hardy, one day. "My men were so rushed with work that they simply could not take the time to go hunting round for clues. But now that the wireless patrol has furnished those clues, we shall be able to follow them up. But we want you to continue at work just the same. You can still help us."

But the members of the wireless patrol, and especially Henry, found small satisfaction in the Chief's praise. They had not come to New York merely to furnish the secret service with clues. They had come to uncover the system by which spies were betraying the movements of our transports. At the Elk City reservoir they had succeeded where trained men had failed; and they meant to succeed here also. They felt that the Chief was patting them on the head, as it were, and telling them that they were good little boys. They meant to show him they were the equals of his own men, even if the Chief's words, instead of pleasing them, stimulated them to half angry activity.

"He needn't think that just because we're boys and come from the country we aren't any good," argued Roy. "That's the way everybody talks about boys. That's the way they talked about us at Elk City until we caught the dynamiters and showed them what we could do. We'll show Uncle Sam's men, too. I don't care if they are famous detectives. We'll get these fellows ourselves. We're not going to have the secret service step in now and take all the credit."

But it was one thing to talk so confidently and quite another to accomplish the end they were striving for. They had not yet discovered a single one of the hidden wireless stations, and the secret of the dollar was still a secret. As far as the members of the wireless patrol could see, it was likely to remain a secret. How they could secure one of the dollars without being detected, they did not know; and how they were to read the message, even if they did get the dollar, was more than they could see; for by this time they had dropped the idea that the messages were engraved on the coins. More and more those dollars appeared a great and insuperable obstacle.

"Couldn't we manage to see the spy when he marks those dollars?" asked Roy. "Is there any way that we could get into his house and hide, so as to watch him?"

"You mustn't think of trying," said Captain Hardy decisively. "But possibly you could find a new place to watch from that would enable you to see him better. These field-glasses of mine are very powerful, and if you can find the proper view-point, you can see him well, even from a distance."

Without a word Roy grabbed his hat and darted out of the house. A second later he was slipping through the thicket on the sloping hillside. Cautiously he crawled from one point to another. The only station that gave any promise of success was the pine grove originally selected. The tree from which they had been watching the spy's house was a giant pine that towered above every other tree in the grove. But the scouts had never dared to ascend beyond the protecting foliage of the other trees, lest they be detected. So they had been looking upward at an angle, as they watched the spy's house. Roy now saw that if he were to climb high up in the big pine, he would be on a level with the spy's windows, and could doubtless see clearly into the house. The difficulty would be to make the climb without being detected.

Roy made his way back to headquarters and reported on his observations. "I didn't go up," he said, "for fear he would see me."

"You were wise," replied Captain Hardy. "We must devise some plan by which you can get up the tree unnoticed."

"Camouflage!" said Willie suddenly. "Fix one of us up like a pine tree. Then he won't see us."

"Just the idea," said Lew laughing.

"We'll have to use the smallest boy in the bunch," said Captain Hardy, "and that's you, Willie. Come. We'll see what we can do with you. Go get me some samples of pine bark and needles."

Willie speedily got the desired objects. Captain Hardy examined them critically. "You ought to have a dark brown suit, painted with irregular stripes, like branches, and dabs of green, like foliage."

"Don't forget his face," cried Roy in glee. "That will have to be painted brown and green also."

A laugh went up. "I'm merely telling what ought to be done, Willie," said Captain Hardy reassuringly, "not what we shall do. We have to guard against observation by persons other than this spy. If the neighbors saw a boy going out of here garbed the way you want Willie fixed up, Roy, they would begin to ask questions. And we don't know what the spy's relations are with his neighbors. What we shall have to do is to dress Willie in clothes as nearly the color of the tree as possible. We can get shoes, stockings, and a suit of clothes to match the tree trunk. We can get a cap the shade of these pine-needles. That leaves hands and face. They, too, must be disguised. A pair of gloves of the proper shade will take care of the hands. But what about the face?"

"Nothing for it but to paint it," said Roy, his eyes dancing.

"I guess you're right," said Captain Hardy. Willie made a wry face. The captain saw him. "The trench raiders blacken both their hands and faces when they steal out into No Man's Land at night," he said. "But we won't use real paint, Willie. We'll get some theatrical paint that comes off easily. I'll get the necessary materials at once."

He noted down the sizes needed and went out. And it was well he acted so promptly. That very afternoon a message from the secret service informed them that more transports were sailing.

"Come with me and get on your pine tree outfit, Willie," suggested their leader. "You other boys go to your stations at once."

Henry's task henceforth was to trail the driver of the roadster. He hurried away to his waiting motor-cycle. Lew was at the wireless key again. Roy scurried out to the pine grove, and Willie followed his captain to be "camouflaged." A few moments later, dressed in his new brown clothes, and a chocolate brown in complexion, he slipped from the house and joined Roy.

Impatiently they waited for the first transport to appear. It was a long time coming. But finally Willie picked it out with his glasses, far up the Bay, as it nosed its way steadily through the rolling waves. Behind it was another transport. As the ships drew near, Willie mounted as far up in the tree as he dared, crouching behind the tops of the surrounding trees, and hugging his own tree trunk, motionless, awaiting his opportunity to climb to his ultimate post. His heart beat fast. His legs shook slightly with excitement. He was trembling all over, so eager was he to make the ascent. On came the boats. Long ago they had passed Robbin's Reef. Now they were well into the Narrows. Suddenly the spy appeared at his window, sweeping the channel with his glasses, his hands shutting off his vision on the sides, like blinders on a horse. Quickly Willie scurried up the tree, wrapping himself closely about the slender trunk, concealing as much of his body as he could, and snuggling behind the sparse clumps of foliage. Then he brought his glasses to bear, and sat silently studying the spy's house.

The interior of the dwelling was as he had guessed it to be. There was no partition wall in the forward part of the building, a single column upholding the ceiling, so that, above the low sash curtains, Willie could see entirely through the glassed-in room. This was more than comfortable. Willie saw a row of low book-shelves lining the north side of the great room. There were numerous fine pictures and plaster casts here and there. A piano stood in one corner, a talking-machine in another. The light within seemed to flicker, and Willie guessed that in the rear of the room, where he could not see it, a log was burning in an open fireplace; for the days were growing very chilly.

But before Willie could complete his observations, the spy turned from the window and walked toward a large, flat desk in the centre of the room. Willie shrank close against the tree and remained as motionless as a stone image. But the spy never once glanced out of the window. He sank into a chair before the desk, switched on an electric desk light, and began to write on a piece of paper. Evidently he was arranging his message. When this was done to his satisfaction, he reached into the desk and drew forth a dollar. Willie could see it plainly as the spy laid it on his desk blotter, under the lamp. Intently Willie strained forward. The spy leaned forward and fumbled about the bottom of his desk. His hands and arms were hidden and Willie could only conjecture what was happening. Then Willie gave a little gasp of surprise as the spy straightened up and laid on the blotter beside the dollar a curious little thing like nothing Willie had ever seen. Evidently it was of metal for it shone under the light. Willie screwed up his face as he strained his eyes to identify the object. It seemed to be a disc of exactly the same size as the dollar. Yet it was not solid, because Willie could see the blotter through it. To Willie the thing resembled nothing so much as a spider-web. What it was, Willie could not even guess.

Meantime the spy had pulled open a drawer, from which he took a slender instrument, which also Willie could not identify. But evidently it had a sharp point; for the spy, after placing the disc on the dollar, scratched the milled edge of the coin with the little instrument, then he began to make marks here and there through the little disc, on the surface of the dollar. From time to time he turned the coin, and occasionally he looked at the writing on his paper. He seemed quite expert, for he worked fast. He finished his task and leaned over behind his desk, evidently to put the curious disc in its secret repository.

Quick as a flash, Willie slid from his exposed perch and safely gained the concealing shelter of the lower tree tops before the spy straightened up again. Willie climbed on down the tree and joined Roy at the usual observation post.

"What did you see?" asked Roy eagerly.

When Willie had told him, Roy groaned. "Gee! That makes it all the harder. Now we've got to get one of those discs as well as a marked dollar before we can discover how they send their messages."

The grocer's boy came and went. Roy trailed him back to the store, but prudently kept out of sight. There was nothing to be gained by entering the store again. Meantime Willie scrambled up to the house and related to Lew and his captain what he had seen. And they agreed with Roy that the problem, instead of being easier, had become more difficult.

CHAPTER XIII

WHAT HENRY DISCOVERED

Henry, meantime, was waiting at his station with eagerness and quickened determination. Despite his leader's generous words, Henry felt in his heart that his last effort had been a failure. It was true that he had made it possible to learn the identity of the driver of the roadster, and that the secret service men had in the meanwhile been looking up the man's record; but Henry felt that he should also have discovered the location of the secret wireless. Now he made up his mind that nothing should balk him in the present attempt. That neither accident nor anything else should hinder him from accomplishing his purpose. He would be more skilful than he had ever been before. He would watch closer. He would follow his quarry, as silently as a shadow and as closely. He would do all that his leader expected of him—and more.

Thus resolving, steeling his mind to the greatest effort of his life, Henry stood at the little window in the garage, all atremble with eagerness. He thought he knew every inch of the spy's roadster, but when that car finally rolled past, Henry studied it as he had never studied anything before. Again he noted the tread of each tire and looked for cuts or other distinguishing marks in them. As good luck would have it, a turning wagon obstructed the roadster just as it reached the little garage, and the roadster came almost to a dead stop. Henry studied its running-gear, its radiator and bonnet, its dash-board and wind-shield. And when his eyes got so far, they went no further. The standards that held up the wind-shield were bulkier and thicker than any other such parts Henry could remember. The difference was not great, yet there was a difference; and like the accomplished scout he was, Henry noted that difference and questioned it. But, like Willie with the spider-web disc, he was completely puzzled. The enlarged standards might mean anything or nothing. The car rolled on and again Henry looked in vain at the number. Some part of it was always dust covered. But Henry observed that the hidden figures were not the same from day to day.

When the car returned from the grocer's, Henry jumped to his motor-cycle and made his way to the ferry by a route different from the roadster's. He knew he was taking a chance, but he also knew that an accomplice might be trailing the roadster to see if the latter were watched. Henry could follow the spy to the ferry once without arousing much suspicion; but if he were twice seen to do so, his usefulness might be ended. He knew when the ferry-boat would leave its slip and he made his way aboard just before the gate closed.

At once he had a feeling that he had acted wisely. The roadster was again in the forward part of the boat, but this time the driver did not sit placidly looking out over the Bay. He seemed nervous, and every little while turned sharp around and looked about him. Fortunately Henry had concealed his wheel behind a truck and was himself where the spy could not see him. When he noted the spy's restlessness, it flashed into his mind that perhaps the secret service men who had been investigating this spy had not been so careful as they should have been, and that the spy had taken alarm. It was a discouraging thought, for it made Henry's task vastly more difficult. Wisely, therefore, he went into the cabin and sat down. The spy could not see him, and if the latter should stroll about the boat, there was nothing to indicate to whom the motor-cycle belonged.

As the gate opened and the roadster rolled from the ferry-boat, Henry prudently remained well behind it. Up Broadway they went, as fast as the traffic would allow, their pace gradually quickening as they drew away from the congested lower end of the island. The spy drove straight up Broadway. He circled Union Square and continued north. He passed Madison Square and still held to Broadway. Past the shopping district, past Longacre Square, past Columbus Circle, the roadster continued, still on the city's main highway. And at a discreet distance Henry followed.

Now they reached the apartment-house district and slid past block after block of bulky living apartments. And so they continued past Columbia University and down the grade beyond. And here Henry's troubles began. The roadster turned to the left, and Henry knew the driver was making for the Fort Lee ferry.

How should he gain the boat unnoticed? How should he follow, undetected, along the Jersey roads? For after they had crossed the Hudson there would be an end to that concealing traffic that had so far hidden him. He must follow the roadster over lonely roads and yet remain unseen. It was a problem to disturb any one. And it worried Henry not a little. Fortunately dusk was at hand, though the curtaining darkness would not fall for some time.

When the boat reached the Jersey shore, Henry permitted the roadster to get a long start before he went ashore. The spy turned to the right and began to climb the long grade parallel to the river, that would lead him to the top of the Palisades. When the roadster was almost out of sight, Henry mounted his motor-cycle and followed. Even if his quarry should pass completely from view, Henry had no fear of losing him; for the roadster's tracks were plain in the dusty road.

The dusk deepened. As it grew darker, Henry came closer to his quarry, though he kept behind elevations and curves in the road so as still to remain invisible to the driver of the car ahead. Thus they rode for some miles. The country was as Henry had pictured it from his study of the maps. It was sparsely built up, woodlands were on every hand, and the surface of the land was rolling and rock-strewn. It was an excellent place in which to hide—and also an excellent place in which to dodge one's enemies. As Henry thought of this, he drew closer and closer to the car, though still seeking to remain out of sight. As the light failed, and it became difficult to distinguish the marks in the dust before him, Henry drew up so that he could see the roadster, but he discreetly rode close to the side of the highway, where the overhanging trees shadowed him. Even had the roadster's driver been looking straight in his direction, he might never have seen Henry. He was, as he had determined to be, a veritable shadow.

So they rolled northward. At last it grew dark. The driver of the roadster switched on his lights. Now Henry crept still closer. He was in the dark, his lamp unlighted, his motor running silently, and he had no further fear of discovery.

It was well that darkness had come. They had now reached a lonely region where there were few houses. Here, Henry judged, was an excellent place for a secret wireless. And he judged correctly, for hardly had the thought come into his mind before the roadster turned sharply to the left and disappeared. Henry darted up the road. He came at once to what he judged was a large field. Trees no longer bordered the highway on the left side. Dimly Henry saw objects here and there which he thought were boulders and clumps of bushes. He saw no light and stood for a second peering into the darkness, listening with bated breath. Straight ahead of him he heard the faint purring of a muffled motor. He knew that he was not many hundred feet behind it and that this time the car could not escape him. He thrust his motor-cycle into some near-by bushes, first whipping out his metal cane. Then he ran speedily but carefully after the car.

Evidently it was moving cautiously. Henry rapidly drew near to it. When he had come so close that he could see it distinctly, he dropped to a walk and began to look about, trying to see what was around him. Here in the field it was lighter than it had been on the highway under the shadowing trees. The field was, as Henry had guessed, a piece of wild land, grown up with thickets, with great boulders here and there. Directly ahead of him was a clump of bushes. Henry hastened to put them between himself and the car. It was well he did; for hardly had he gotten behind them before the car stopped and the driver got out. The car was not more than two hundred feet distant.

Henry dropped to the ground and lay still for a moment. Then he crept, like an Indian, toward the sheltering thicket. Through it he advanced until he was not more than fifty feet from the motor-car. He could see with fair distinctness, but was himself completely concealed. He lay like a log, watching intently.

The driver unfastened his top and slid it backward. As he did so, his overcoat caught on the open door and he gave an exclamation of impatience. When he had laid his top back, he lowered the upper half of his wind-shield. Then, standing on the running-board, he tugged at the top of his wind-shield standard. Up came a sliding inner tube. In a flash the entire mystery stood revealed to Henry. The wind-shield standard contained a collapsible mast, like the telescoping cane he held in his hand. Doubtless an aerial was now fastened to the mast. Somewhere within the car was a wireless outfit. Instead of having many secret stations, the Germans had this one portable station.