He was not a second too soon. In his eagerness to get the coin he had been clumsy, and had fumbled excitedly for several seconds before he found it. Meantime, the spy, with practised skill, had taken down both wires and fastening, and was well on his way back to the car. But Henry gained his cover and was safe.

A sudden fear smote him lest he betray himself. His heart beat so loudly he was sure the spy would hear it. His breath came so excitedly he was certain he could be heard yards away. For some time he crouched motionless, hugging the ground, trying to hold his breath. But as second followed second and the spy made no outcry, Henry gained confidence. Suddenly a feeling of exultation came to him, so strong that he could hardly refrain from shouting. For the first time he thought of the real significance of what he had accomplished. He had unraveled the mystery of the wireless. He had the dollar. The secrets the wireless patrol had worked so hard to uncover were within his grasp. As the full meaning of it all came to him, he felt that he must cry out, that he must give voice to his feelings. He no longer dared trust himself to remain where he was, lest he betray himself. Clutching the dollar as he had never clung to anything in his life, he picked up his cane and slowly began to worm his way backward, on his belly, from the thicket. With the utmost caution, an inch at a time, he moved, lest he snap a stick or strike a stone with his foot. As soon as he was clear of the brush, he faced about, and crawled into the darkness.

The spy, meantime, was proceeding rapidly in reassembling his car. Henry heard the windshield go up and the top being fastened. He heard the baggage lid snap into place. Then he heard the spy swearing in a low voice. Henry stopped, still as a hunted rabbit.

"Donnerwetter!" he heard the man say. "I've lost that dollar." There was a pause. Then came the words, "I'm not going to hunt for it anyway. Somebody would see my light sure. And if anybody does find it, he'll never guess what it is."

Exultantly Henry rose to his feet, and crouching low, ran with soft, swift tread to his motorcycle. He had the dollar. The owner believed it was lost. Never was such luck. Trembling all over, he fastened his cane to the frame of his wheel, trundled his car to the road and ran with it in the direction he had come. He pushed it until his breath was coming in gasps. Then he turned into the woods and hid. He would take no chance of being seen by the spy or by any accomplice who might have followed him. Presently Henry heard the motor-car pull out into the road and go speeding back toward Manhattan. A quarter of an hour later Henry returned to the highway, switched on his light, and was soon bowling along on his way to his fellows and his chief, feeling that he had in his keeping the future safety of a nation.



CHAPTER XIV

THE RIDDLE SOLVED

In the house above the hawk's nest, four boys and a man sat far into the night, examining a marked dollar and trying to unravel the secret of the scratches. From hand to hand the dollar passed and was examined now this way, now that; but the little group could see no meaning in the apparently aimless marks on the silver coin. Had some of them not seen this dollar marked and its message deciphered and sent vibrating through the air, they would have refused to believe that the coin before them carried a message at all. It looked like any dollar that has accidentally become marked.

"To-morrow," said Captain Hardy, "we will turn the dollar over to the secret service, and doubtless their experts will solve the problem quick enough. But I certainly wish we could unravel this thing ourselves. Wouldn't it be an achievement for the wireless patrol!"

"It's going to be," declared Roy positively. "We're going to solve it. We've just got to. We'll show those secret service men that boys are some good after all."

But the word was easier than the deed. Puzzle their brains as they might, search the dollar as they would, they still found no key to the language it spoke.

"Tell me again what the message was," demanded Henry for the twentieth time, and Lew once more passed to Henry the slip of paper on which he had written the message, both in cipher and deciphered, the message he had picked from the air. It read as follows: TRPSLOWAOSEDONBADATSTITY.

T R P S L O W A O S E D O N R A D A T S T I T Y

Long Henry studied the piece of paper, softly reading the message to himself. "Two transports sailed to-day. How did that automobile driver get that message from this dollar?" he asked himself, and again he picked up the coin and turned it in his hand. "If only we had that disc," he sighed, "or a duplicate."

At the word "duplicate," Roy pricked up his ears. "Maybe we can make one," he said.

"Likely!" scoffed Lew.

"You never know till you try," rejoined Roy. Then he turned to Willie and demanded, "What was the disc like that you saw?"

"If I knew, I'd make one," said Willie.

"Well," said Roy in a tone of disgust, "you know whether it was a foot across or not, and whether it was round or square."

"It was round, of course," said Willie, "and the same size as the dollar. I told you that before."

"We can make a disc the size of a dollar, anyway, even if it doesn't get us anywhere," said Roy, putting the coin on a sheet of paper and outlining it with a pencil. Then with scissors he cut the disc out.

"You saw that disc, or one like it, Henry," continued Roy. "What did it look like to you?"

"Just like a spider-web, as Willie says," replied Henry.

"All right, we'll make a spider-web," said Roy.

He seized his pencil, made a dot in the centre of the disc, and from the dot drew straight lines that radiated in different directions. Then he drew a number of concentric circles about his dot.

"I don't see how that helps any," he said, examining his drawing. "Yet that's the kind of thing they used to mark that dollar."

From hand to hand the paper passed, and each boy compared it with the dollar. But none was any the wiser when he had finished. Their leader, meantime, sat with his head in his hands, studiously turning the matter over and over in his mind. For a long time he could make nothing of it.

After a while he looked up. "Let me see that paper," he said.

Roy handed him the little disc. Captain Hardy laid the disc beside the dollar on the table, and painstakingly examined again the marks on the coin. After a time he took a sheet of paper and across it in a row wrote down the letters of the alphabet. Then he picked up the message and made check marks below the letters in his alphabet as he found those letters in the message. When he had gone through the message, his paper looked like this:

ABCDEFGHIJKLMNOPQRSTUVWXYZ / // / / /// /// / / / / / /// / / // /

He picked it up and studied it. "Four T's," he said, "three S's, three A's, and three O's. That ought to give us a clue."

Again he turned to the dollar and began to study it, turning it slowly round, counting the scratches this way and that, making geometric figures of them. Four heads peered over his shoulder as he worked silently with his pencil.

"I can make nothing of it," he said after a time.

Again he sat in deep thought, his fellows meanwhile once more examining dollar and disc and the figures their leader had made on the paper.

"Four T's," repeated Captain Hardy after an interval. "Surely that ought to give us a clue."

Once more he studied the penciled disc. Then he turned to the dollar and again examined its markings. He suddenly exclaimed, "Here are four scratches in a straight row." His eyes began to shine. Slowly he turned the coin. "And here are three in another row, like this," and he indicated the positions of the scratches on the paper disc. "You notice that each row runs from the centre of the coin toward the edge. Let's see if there are any more rows."

Very slowly he turned the dollar. "And there are three in a row," he said, indicating the scratches with his pencil, "and here are three more. You notice that the rows all radiate from the centre, like spokes in a wheel. I believe we are getting somewhere, boys."

"'Like spokes in a wheel,'" repeated Roy to himself. "Rows of letters like spokes in a wheel. Four scratches in one row or spoke—these must be the four T's. Three scratches in these other rows must be O's and A's and S's. I've got it! I've got it!" he suddenly shouted. "There must be as many spokes as there are letters in the alphabet."

"I believe you are right, Roy," said Captain Hardy, looking up with a gleam in his eyes. "That's exactly what I am beginning to think. We'll soon see if you are right. Make me another disc."

With a pocket rule he measured the diameter of the dollar. "Practically an inch and a half," he announced, putting down the figures 1.5 on paper. He multiplied those figures by 3.1416.

"That," said he, pointing to the resulting figures, 4.71+, "represents the circumference of a dollar. Now we'll divide the circumference by 26, the number of letters in the alphabet."

He performed the division. "Eighteen one-hundredths of an inch," he announced. "That's practically a scant fifth of an inch. We'll call it so, anyhow," he continued as he marked off the space on a sheet of paper with his rule. "Each sector," he said, "gets exactly that amount of space on the circumference."

He pulled open the drawer of the desk and began to rummage through a tray full of pens, pencils, and other drawing materials. "I wonder if there is such a thing as a pair of dividers here," he remarked. And a moment later he exclaimed "Good!" and drew forth the compasses he was looking for.

He set his dividers according to the space he had marked off with his rule, then proceeded to divide the circumference of the new paper disc. When he had gone completely round the disc, he seized pencil and ruler and began to draw lines from centre to circumference—the spokes of his wheel—each spoke running from the dot in the centre to one of the points indicated by the dividers. When he had finished, the disc was divided into twenty-six equal sectors, like tiny pieces of a pie.

"We shall soon know whether you are right or not in your guess, Roy," said Captain Hardy.

He laid the dollar beside the disc and began to copy on the disc the marks on the dollar. "We'll put four marks in this sector," he said, making four dots with his pencil. "They are like those four scratches here," and he pointed to the four marks in a row on the dollar. "They must be four T's. At any rate we'll call this the T sector. On the dollar you notice this row of three scratches—the next sector to the left of the T sector. You remember we had three O's, three A's, and three S's. These three scratches must, therefore, be O's, A's, or S's. Since they are next to the T's, they are doubtless S's. I'll mark the sector so anyway. That gives us the T sector and the S sector. If we are on the right track, then the sector to the left of the S space is the R sector, and so on. I'll mark the disc that way, anyhow."

Slowly he turned the disc around, putting a letter at the bottom of each sector. When he had finished, he had completed the alphabet. About him clustered his four comrades, too deeply interested to speak. They hardly even breathed.

"Take this paper, Roy," said Captain Hardy, "and tell me how many times each letter in the message appears."

Roy took the paper on which Captain Hardy had made his numerical enumeration. "Three A's," he said.

Captain Hardy made three marks in the A sector.

"No B's, no C's, and two D's."

The D's were scored. So they went through the alphabet. When they were done, the markings on the disc were practically a duplicate of those on the dollar, for Captain Hardy studied the dollar each time before marking the paper disc.

"That's it," cried Willie. "That's it exactly."

"It's right so far as it goes, Willie," said their leader, "but we haven't all of it yet. Suppose I hand you a disc with four T's, three S's, two Z's, three L's, and so on. Could you make a message out of it?"

Willie studied the disc on the desk. "No," he said, "I couldn't. I shouldn't know how to arrange the letters to make words out of them."

"Neither would anybody else," continued Captain Hardy. "Those spies have some way of knowing how to tell the order in which to read these letters."

For some time he sat studying the scratches on the dollar. The four boys were quiet as mice, each trying to solve the problem that stood between them and complete mastery of the cipher.

"You said that the metal disc resembled a spider's web," began Captain Hardy, talking more to himself than to the boys. "We know what the straight lines—the spokes—are for. The concentric circles must be to indicate the order of the letters. Let me see." Again he studied the dollar closely. "Some of these marks are near the centre of the disc, some half-way between centre and circumference, and some close to the outer edge. I believe the secret lies there."

"Listen!" cried Willie of a sudden. "When a spider spins a web, she begins at the centre and works outward. Maybe these spies write their messages in the same way."

"Willie," cried Captain Hardy, "you've hit it exactly. You're as good a reasoner as you are an observer. Now we'll begin at the centre and spin this message outward. What's the first letter?"

"T," said four voices together.

The captain took his dividers and found the scratch nearest the centre of the disc. In the same sector with this scratch were three other scratches in a line.

"It's a T," he announced, "just as it should be."

With his dividers he found the letter next nearest to the centre. It stood alone. "That's a W," he announced.

Rapidly he located the scratch the third nearest to the centre. "And that's an O," he said, looking up with flashing eyes. "We need go no farther. We have the entire secret. We have deciphered their cipher."

A cry of exultation arose.

"To-morrow," continued Captain Hardy, "we will get a piece of transparent celluloid and make a disc like their own. We can ink in the circles and the radius lines and our disc will be almost a duplicate of theirs, except that our disc will be solid while their discs have open spaces between the circles. But that is only a detail. We can read their cipher as well as if we had one of their own discs."

"Wait," cried Willie, as his comrades started to cheer again. "What is the scratch on the milled edge of the dollar for?"

"That," replied Captain Hardy, "is to indicate how the disc is to be placed on the dollar. That scratch is exactly between the Z and the A sectors. It shows where the alphabet begins. Now we have their entire secret."



CHAPTER XV

ANOTHER MYSTERY UNRAVELED

A piece of transparent celluloid, furnished by their host from a broken side curtain of his automobile, supplied Captain Hardy with the material needed for making the disc that was to be the key to future communications of the enemy. Carefully he cut the celluloid the size of a dollar, then marked the exact centre of it. Next he clamped the disc on the captured coin. Between the rows of letters he scratched in the straight radius lines—the spokes of a wheel. Then Captain Hardy put the end of one arm of his dividers in the dot at the centre of his disc, and swept the other arm around, scratching a circle just outside the first letter in the message—the innermost T. Examination showed that this circle fell just inside of the second letter in the message—the W. Adjusting his calipers, the draughtsman made a second circle, just outside of this second letter. A third circle fell between the first O and the second T of the message. So Captain Hardy continued, each succeeding circle falling just outside of the succeeding letter in the message. When he had finished, his disc contained twenty-three concentric circles, between which could plainly be seen the bright dots or scratches in the dingy dollar.

"Whew!" said Captain Hardy, as he laid down his dividers. "That's pretty fine work—twenty-three circles within a space of an inch and a half. I'll wager a watchmaker made their pattern for them. The solid parts of their metal discs can't be much larger than these lines I have scratched on the celluloid. You were right when you named it, Willie. The parts of it must be just about as thick as a spider-web."

The boys passed the dollar and its superimposed disc from hand to hand, examining them with eager interest.

"Suppose they wanted to send a message with more than twenty-four letters in it," said Roy. "How could they do it? I'm sure some of the messages we intercepted had more than twenty-four letters in them."

Captain Hardy picked up the disc-covered dollar and studied it intently. "I suppose," he said after a time, "that they would put more than one dot in the same circle, and the dots would be read in the same way they are now. The one to be read first would be nearest the centre of the coin, and so on. Or they could write on several coins, each coin being numbered in some way, and corresponding to a paragraph in a composition."

Again he studied the dollar closely. "Clever!" he said admiringly. "Mighty clever! Who would ever dream that those tiny scratches meant anything? Many a time I've seen a dollar scratched and nicked a deal worse than this one is, though they've evidently chosen a battered one so that their own marks will be less noticeable. Why, that coin might have passed through our hands a hundred times, and if we had not actually seen it marked we should never dream it said anything other than 'In God We Trust.' We've had a great stroke of luck, boys."

He paused and meditated. "I wonder if it is luck," he went on. "May not the motto on that dollar explain our good fortune? Perhaps it is Providence rather than blind luck that has guided us. At any rate let us hope so. Now I'm going to report to the Chief. Won't he get a surprise?"

And Captain Hardy left his subordinates, chuckling at the prospect of the Chief's astonishment.

But it was Captain Hardy who had the surprise. Instead of the stern, silent, brusque man he had become accustomed to, Captain Hardy found the Chief smiling and talkative. As his eye fell on Captain Hardy, the Chief rubbed his hands with apparent satisfaction. Evidently something had happened that had put him in an extremely good humor.

"Ah! Captain Hardy," he said, "we beat you to it this time. I already know what you have come to tell me. But I am glad to see you just the same. One of our operators," continued the Chief, "happened to be shifting his tuning-coil when our friends, the enemy, were sending their message yesterday afternoon, so that I have all the latest spy news."

He paused and smiled at his astonished visitor. "You see," he added, a real Irish twinkle coming into his eyes, "the secret service is not so slow after all."

"Congratulations!" cried Captain Hardy, in the same spirit of fun. "The secret service is improving. But I have some news that may make my trip not altogether without interest to you."

The Chief interrupted him. "We know who the man is that has been telephoning to your Staten Island grocer about sugar," he said. "When he called up yesterday afternoon, the telegraph operator flashed the tip to my man, who happened to be on duty within a few doors of the place the man was talking from. Of course my man spotted him and trailed him. The fellow proves to be a clerk on one of the piers where transports are loading. His position gives him no opportunity to get aboard the ships, so he does not know what goes into the transports. But he does know how many boats are loading and about when they will sail. Evidently he is afraid to telephone directly to any of the better known German agents we are watching, and as far as that goes he may not even know who they are. I suppose this plan of communicating with Staten Island is to give the spy there a chance to observe the transports as they sail from the harbor, and see if he can learn anything about their cargoes. We have put this steamship clerk under observation and from now on he will be watched night and day. We're closing in on them fast."

"Congratulations!" cried Captain Hardy again, this time in sober earnest. "You are doing excellent work. Now when you hear what we——"

Again the Chief interrupted him. "Oh! I haven't told you all my news yet, not by a long shot," he said. And again the head of the secret service rubbed his hands together. "We know who the driver of the wireless motor-car is. I don't mean we know the name he's using. Anybody could get that out of a directory. It's Sanders. But we know who he really is. And that's why we feel so good to-day. He's a man we've been looking for for months. He is one of the German agents implicated in the papers we seized in Wolf von Igel's office. The secret service has been more than anxious to discover his whereabouts. Now we have him, for he's under observation and cannot escape us.

"He came to this country about a year before the war started," continued the Chief, a gleam of satisfaction shining in his eyes, "and bought out an insurance agent who made a specialty of insuring suburban properties. From the beginning, he made a practice of visiting the properties that he insured. This took him about a good deal and gave him an excuse for being so much in a motor-car. Ah! What an ideal situation for a spy! Clever, aren't they?"

But the Chief gave his visitor no chance to reply to his query. Smiling again, he went on, "But even this is not all. Of course you understand, Captain, that your boys are not the only amateurs helping us out in this pinch. Ever since we became convinced that the Germans have a line of secret wireless stations by which they are relaying news to their agents in Mexico—for we're morally certain that is where these messages go—we've had trusted amateurs helping us just as you have helped us—by listening in. Some of them have been at it for weeks. When we could get no trace of secret messages along the direct route to Mexico, where they would naturally have their stations, we began to suspect that the Germans were using a round-about route in the hope of deceiving us completely."

"And you've located some of them?"

"Exactly. Your boys will tell you that yesterday was one of those days when radio communication is at its best—when an operator picks up sounds that at other times he could not possibly hear. The result was that we picked up yesterday's secret message at half a dozen different points. Where do you think the first one was?"

"Give it up."

"Buffalo—north instead of south. Clever, eh? Then we got it near Detroit, and Milwaukee, and Omaha, and Santa Fe. Finally one of our listeners picked it up at Socorro, a place about one hundred and seventy miles north of El Paso. Now we know the line of their stations. We'll set a regiment of amateurs to listening in along that line and we'll locate every station in it in no time. Then we'll grab all their agents at the same time in one big raid and wipe out this spy system for good."

"That is great news," said Captain Hardy, his eyes sparkling with interest. "Great! You certainly have cause to feel good."

"For a little while," replied the Chief, "I thought I had even more good news. But it proved to be a false alarm."

"What was it?" inquired Captain Hardy as the Chief stopped speaking.

"Oh! Simply this. Some time ago one of our listeners caught an earlier message near Socorro, which gave us a hint as to where the messages were crossing the border. We at once sent a number of expert army wireless men into that part of the border region to listen in. One message was picked up at a point fifty miles north of the boundary, but it was very faint. Along the line itself the radio men have never detected a sound. Yet your boys are intercepting the messages here, so we know that they are being sent regularly. That made us think that perhaps the messages were being telephoned the last lap of the journey and carried over the line by a person."

"I have no doubt that your theory is correct," said Captain Hardy.

"Well, last night we thought for a time that we had the man who was carrying the messages. When my operator here picked up the message yesterday afternoon, I instantly sent a message to my subordinate in charge of the work in the El Paso district, telling him of the sending of the message and urging extra vigilance. Yet not one of the radio men heard a sound. But in the middle of the night my men grabbed a Mexican who had slipped past the armed guards and was starting to wade across the Rio Grande to Mexico."

"Excellent!" cried Captain Hardy.

"Good enough as far as it went," said the Chief, with a wry face, "but it didn't go far enough. The fellow was only a smuggler."

"Are you certain, Chief?"

"Sure as preaching, worse luck."

"Was the man searched thoroughly?"

"Now, Captain, what do you think the secret service is, anyway? Was he searched! It would make your eyes pop out if you'd see the way we go through a man. We strip him and give him a lemon bath to bring out any secret message that might be written on his skin, and we take his clothes apart scientifically, I tell you. No, this fellow had nothing incriminating on him. After a grueling examination, he admitted that he had crossed the line to smuggle in some tobacco. However, it's only a question of time until we do put our finger on the missing link. Then for a great raid!"

"How I shall welcome that day," said Captain Hardy. "This spy business is never absent from my thoughts, with its menace to our boys on the ocean."

"I think that you will soon be free to go back to the army," said the Chief. "Your work is about done. This thing is coming to a head fast now. But of course I shall need your boys to listen in for a time, so that we can know what the Germans are sending. But there will probably be no more real work for you. We certainly are grateful for the help you gave us, though. We have been terribly crowded these last few weeks."

In his pride at the work his boys had done, Captain Hardy momentarily forgot the errand that had brought him to the Chief's office. He stood before the head of the secret service, smiling happily. Again he began to think of that long chain of secret wireless stations, so sinister and so menacing, with voice crying treachery to voice through the air, carrying word that at any time might cause the murder of thousands of our brave soldiers. Mentally he journeyed along the line of those stations—from New York to Buffalo, to Detroit, to Milwaukee, to Omaha, to Santa Fe, to Socorro, to Mexico. With quick imagination he pictured the scores of little secret stations needed to carry those treacherous messages across so vast a span of earth. Some he saw skilfully hidden in forests, as the wireless had been concealed at the Elk City reservoir. Some he pictured in abandoned farmhouses. Others he saw in barns, in the stacks of ruined factories. And some he imagined as flinging their voices abroad amid the burning plains of the arid border-lands. But he could not picture to himself the invisible messenger that took the word across the boundary. He could not fathom the mystery, he could not picture to himself the missing link in the chain. As was always the case with him, his mind began at once to grapple with its problem—in this instance the riddle of the missing link. He actually forgot where he was.

"I wonder," he said, though he was really talking to himself, "what was done with that smuggler."

"We clapped him into jail to await trial for smuggling," said the Chief.

Captain Hardy came to himself with a start, and smiled. "You say they got nothing incriminating on him," he remarked. "Did your men find anything at all?"

"Only the money he had gotten for his tobacco."

Mechanically Captain Hardy had thrust his hand into his pocket. As the Chief answered the question, Captain Hardy's fingers came in contact with a silver dollar and a disc of celluloid. Of a sudden an eager light flashed into his eyes. "What kind of money did that Mexican have?" he demanded.

"Some silver," said the Chief indifferently.

"Of what denominations?"

"Dollars. He had three of them."

"What was done with that money?" asked the captain with an earnestness that was almost tragic.

"Oh! The greaser made such a disturbance that the jailer let him keep it. He's got it with him in the jail."

A great sigh burst from Captain Hardy's lips. "Telegraph your men instantly," he cried, "to get those dollars. That Mexican is no smuggler. He's a spy. He's the man who carries the messages across the border. The messages are on the dollars. And here's the key to the cipher!"

And he drew from his pocket and laid before the Chief a battered silver dollar and a curiously marked celluloid disc.



CHAPTER XVI

AN UNEXPECTED MESSAGE

"Was he surprised?" cried the four boys of the wireless patrol, as their captain entered the living-room after his trip to the secret service offices.

Captain Hardy chuckled. "I think he was," he said. "But for a time it was I who was surprised. The Chief knew from his own men all about yesterday's message. One of them picked it up. What's more, he has a lot of amateurs in different parts of the country listening in, just as you are doing, and they picked up yesterday's message at enough different points to indicate the line of the secret stations we are after. The messages are crossing the border somewhere near El Paso. But the Germans are getting them across in some way other than by wireless. They know we'd spot their outfit quick. The Chief thinks some one telephones the messages the last lap and that a messenger carries them into Mexico."

"And what about the dollar and the disc?" asked Roy. "What did the Chief think of them?"

"Well, he was surprised. And what's more, we got hold of that dollar at exactly the right moment. The secret service men arrested a Mexican who was wading the Rio Grande at El Paso last night. They searched him and found nothing on him that seemed incriminating. They questioned him and the fellow finally said he had smuggled some tobacco into this country, so they put him in jail as a smuggler. The fellow had some money he had gotten for his tobacco—and it was three silver dollars! The secret service men down there knew nothing of what we have found out here, so they gave the fellow back his money. But I am morally certain that their man is the spy who carries the messages across the border."

"Of course," cried Willie. "What else could he be—sneaking across the boundary with three silver dollars."

Everybody laughed.

"It doesn't follow that he's a spy, just because he has three silver dollars. He may be a smuggler, all right enough. But I believe the smuggling is just a blind. If he were a genuine smuggler, he'd bring more than three dollars' worth of stuff across."

"What have they done with his dollars now?" asked Roy eagerly.

"I don't know, Roy. The Chief got into instant touch with his men at El Paso as soon as I showed him the dollar Henry got. But I left before I knew what the outcome was. However, I have no doubt they will find that the dollars are what we suspect them to be."

"Gee!" said Willie. "To think that the wireless patrol found out about those dollars!"

"I guess the secret service knows by this time that boys are worth something," smiled Roy. "Before we get through, they may think so even more."

"You're certainly not increasing in modesty," laughed their leader.

"Well, I don't care," said Roy hotly. "It makes me tired. Everybody says, 'Oh! They're only boys.' Of course we're only boys, but look at what we've done. Why, the wireless patrol has got the best set of fellows——"

But Roy's protest was smothered in a burst of laughter from his fellows.

"Well, I'm glad you feel so good over what we've been fortunate enough to accomplish," said Captain Hardy, "for I fear there will be no more excitement for you. The Chief says his men now have the spy business well in hand, and that all he wants of us from now on is merely to stay here and catch their messages until he is ready to make his raid."

"Just what I was saying," burst out Roy indignantly. "They won't let us in on their raid because 'we're only boys.' But who was it caught the dynamiters, if it wasn't 'just boys'? The men couldn't do it. They tried twice and failed. Gee! It makes me tired."

"Never mind, Roy," said Captain Hardy smiling. "Even if we don't have any further taste of excitement, we can always remember that we had a big part in catching these spies—for they're going to be caught, sure. And you mustn't forget that if we stay here and do well the part assigned to us, we are helping just as much as the men who actually round up the spies. You know Milton says 'They also serve who only stand and wait.' If there aren't any reserves to stand and wait behind the lines, the men on the firing-line do not dare to push ahead. And besides, Roy, it is seldom that four boys play so important a part in great deeds as you four boys already have played."

"Four boys and a man," corrected Henry. "Without you we could never have gotten anywhere," and Henry looked affectionately at his captain.

"Oh! Yes, I had a part in it," agreed the captain, "but it was only a part."

"But you read the ciphers," protested Henry. "If you hadn't done that, we could not have made any headway at all."

"And who caught the messages for me to decipher? The reason we have gotten along so well is because we work together so perfectly. I want to thank you boys for being so faithful. I've given you many hard tasks to do."

"After our experiences at Camp Brady," said Lew, "we couldn't do anything else than be faithful. We know by experience what happens when we don't do our duty."

"Then you are going to listen in during the remainder of the spy hunt," said Captain Hardy, with an affectionate smile, "just as faithfully as though your work weren't already done and the spice gone out of it. I know it will be dull and uninteresting, boys, but you've made such a fine record that I don't want you to fall down now. So be very careful—if only for my sake."

"They've never talked once," said Henry ruefully, "excepting after the transports sail. I don't suppose they ever will except when the ships go out. We'll have to listen to nothing for twenty-four hours a day. But we're going to do it just the same."

He rose and walked toward the wireless room. "It's back to the mines for me," he added. And he disappeared through the doorway of the wireless room.

But hardly had he sat down and clamped the receiver to his ears before he cried out. His fellows came flocking into the room. Henry was swiftly writing a string of letters on a sheet of paper.

"Something of moment must be afoot," said Captain Hardy, in a low voice, "for them to be talking at this time. It must be important, indeed."

"It's a long message," whispered Willie, as Henry continued to fashion letter after letter.

"Something tells me it is important," repeated Captain Hardy. "What can it be? You don't suppose the secret service men have alarmed them, do you?"

Henry finished his writing and laid down his pencil. His chief picked up the sheet of paper and scanned the long line of letters Henry had made, like this:

EEANNRDBOEUNRYWSEUTTERONSNNFEEIAYWMNVTTASANXJULEIGOKWSNVATYIZLETK

"Sixty-five," he said aloud, after counting the letters carefully.

A frown came over his face as he stood looking at the paper in his hand. "Sixty-five," he repeated. "All their other cipher messages have made four even lines. You can't divide sixty-five evenly by four. Boys, I believe—but we'll make sure first."

He sank into a chair, laid the paper on the desk, and arranged the letters according to the old plan, thus:

EEANNRDBOEUNRYW SEUTTERONSNNFEE IAYWMNVTTASANXJ ULEIGOKWSNVATYI

"I don't know what to do with the five letters left over," he said, as he laid down his pencil. Then as he ran his eye down column after column and across each line, he continued, "But I guess it makes no difference. It is just as I thought. I feel more certain than ever that something of great importance is afoot. They've switched to another cipher."



CHAPTER XVII

A CHANGE IN CIPHERS

For some moments there was a complete silence in the room. The members of the wireless patrol looked at one another in astonishment, questioning with their eyes the meaning of this new turn of events. Captain Hardy sat staring at the message before him, his brow wrinkled, his eyelids drawn close together, trying to find some new clue to the puzzle before him. And until he spoke, the lads of the little patrol forbore to utter a sound. So for some time the room remained as silent as a tunnel.

At last the captain glanced up from his paper and noted the intent looks bent upon him, and the deep silence. He shook off his abstraction.

"It looks as though we were up against it," he said. "Every minute I feel more certain that something serious has happened. Why should they be sending radio messages at this hour, when they have never sent them before excepting after the transports sailed? And why should they now use a new cipher? Their plan evidently was to use radio communication as little as possible, lest they be detected. So they sent nothing by wireless but the most important news—the news of ship movements, which had to be got to Germany at once. All other messages they conveyed in some slower but safer way. We know they used the telephone, and sent messages by a boy, and wrote on dollars, and carried messages by motor-car, and probably sent code letters through the mails. For all ordinary correspondence they used these slower, safer methods. Only when they absolutely had to, did they employ the wireless. So we must assume that they had to now."

He paused and glanced from face to face. "But why the change of cipher?" he continued. "It must be because they fear that the old cipher will be understood."

Again the captain fell silent. "What can have happened?" he inquired soberly, "that makes the use of wireless so imperative? What can it be? Only something new and unforeseen. And what could there be new and unforeseen except the detection of their plot? More and more I am convinced that these plotters have been alarmed."

He fell into a brown study for a moment. "This message can mean nothing else," he said after a little. "It is imperative that we learn what it is at the earliest possible moment. Make four copies of the message you took, Henry."

Captain Hardy's first lieutenant took the paper from his leader's hand and on four sheets of paper copied the string of letters he had picked from the air.

"Now, boys," said the leader of the patrol, when the copies were complete, "put your thinking caps on. Each of you take one of these copies and see what you can make of it. You know how we deciphered the other cipher."

In another moment four boys were wrinkling their foreheads as they bent over the cryptic strings of letters. And over the room came a hush deep as midnight's.

For a few moments nobody broke the silence. Each boy was busy with his own thoughts.

Henry was scowling at his paper. Willie was studying the letters before him, as in earlier days he had studied the landscapes about Camp Brady and the Elk City reservoir. Lew already had a hopeless look on his face. At threading the forest he was second to none in skill; but at untangling mental puzzles, he had small ability. The nimble-witted Roy was already setting about his task with that keenness so characteristic of him.

"Sixty-five letters," he said to himself. "If this cipher is anything like the other, those letters must be arranged in columns of equal size."

For a second he sat scanning the letters. Then he muttered, "What will divide sixty-five evenly?" And a moment later, he answered his own query by adding, "Five, and thirteen."

He paused and again ran his eye along the row of letters. "If this cipher works like the other there must be five rows of thirteen letters each, or thirteen rows of five each. I'll try the five rows first. That's more like the other cipher."

Swiftly he set down the five rows of letters, thus:

E E A N N R D B O E U N R Y W S E U T T E R O N S N N F E E I A Y W M N V T T A S A N X J U L E I G O K W S N V A T Y I Z L E T K

Eagerly he ran his eye down the columns of letters, as he had become accustomed to doing with the old cipher, but the letters were unintelligible. Next he read the letters across the rows, but with no better result. The eager look faded from his eyes.

"I'll have to try the other," he said, and began to make his letters into rows of five each, thus:

E E A N N R D B O E U N R Y W S E U T T E R O N S N N F E E I A Y W M N V T T A S A N X J U L E I G O K W S N V A T Y I Z L E T K

With renewed eagerness he ran his eye down the first column. "E-R-U-S-E-N-I-N——" he began, then stopped short in disgust. "Nothing doing that way," he muttered.

Then he read the letters across the rows: "E-E-A-N-N——"

"They've got me stopped," he said. And he threw down his pencil and sat staring at the paper before him, twisting the letters into every shape he could think of, but to no avail.

Meantime each of the other members of the patrol was going through much the same process. Lew gave up first, acknowledging himself beaten. Henry sat scowling and working away industriously. Dr. Hardy tried first one combination of letters, then another, but in vain. Willie had laid out the letters in exactly the same way Roy had. But Willie worked differently from any boy in the group. The rest had been feverishly setting down letters as new combinations presented themselves to their minds, whether the combinations seemed logical or not. Willie first arranged his letters in the long rows and sat for many minutes looking intently at them.

At Camp Brady it was Willie who had learned, better than any other member of the patrol, the lesson of observation. When the patrol was practising scouting, which is only another name for close observing, Willie had sat for hours studying the landscapes, even when his fellows teased him. Thus he had learned to see everything within sight and make note of it. And when a guide was needed later, to conduct a party through the midnight woods in quest of the dynamiters' lair, Willie was the scout who was able to do it. He had observed perfectly and so carefully noted what he saw that even in the darkness he could find his way.

So now he examined his long rows of letters until he knew everything about them; and he was certain they told no story. When he was certain, he rearranged the letters, as Roy had done, in rows of five each. Then he laid down his pencil and began another careful search. He read the topmost line from left to right, and from right to left. It made no sense. He took the second and found no meaning in it. Another boy might have skipped the others, but not Willie. Each of the thirteen rows he studied forward and backward.

Then he ran his eye down the first column, just as Roy had done. It spelled nothing. But when he began at the bottom and came upward, an eager light leaped into his eyes. He could make nothing of the lowest five letters; but the eight above certainly spelled two words: "nine sure." If the message was in English, Willie knew he had found something definite to work on. He could make nothing of the second column, either upward or downward. But the third column gave him distinctly the words "twenty four." The next column yielded more words: "Six twenty."

By this time Willie's eyes were flashing. He turned to the bottom of the last column and began to read upward. A single glance confirmed his suspicion.

"Captain Hardy," he cried, jumping over to his chief, and laying his paper on the captain's desk, "begin at the bottom of the last column and read upward. I believe this cipher is exactly the opposite of the other."

Willie's fellows dropped their pencils and gathered eagerly about their leader as he slowly read the letters, beginning at the bottom of the last column and reading upward and backward in the exact opposite of the way the former messages had been deciphered.

"K," he read, "I-N-G-J-A-M-E-S-T-W-E-N-T-Y-S-I-X-T-W-E-N-T-Y- O-N-E-T-W-E-N-T-Y-F-O-U-R-B-A-L-A-K-L-A-V-A-N-R-E-N-D-E-Z-V- O-U-S-N-I-N-E-S-U-R-E."

"Hurrah for Willie!" cried Roy, who had been putting down the letters as Captain Hardy read them off. "He's solved the problem. Who says boys aren't any good? I'll bet you——"

But Roy was interrupted by his mates. "Read it to us," they demanded.

"It's a funny message," said Roy, and slowly he read the following: "King James twenty six twenty one twenty four——" Then he stopped. "I can't read the next words," he said.

Captain Hardy took the paper from Roy and read the entire message. "King James twenty six twenty one twenty four Balaklavan rendezvous nine sure."

"What a queer message," said Henry. "What does it mean?"

"It means," said Captain Hardy, "that the Germans have done their very best to deceive us. They not only changed their cipher, but they sent their message in code. We have read their cipher, but we know no more than we did before. We can never work out their code. All we can do is to guess at the meaning. Our difficulties, instead of being ended, are just beginning. I am more and more convinced that this message is important."



CHAPTER XVIII

TOO LATE

The look of astonishment that appeared on every face at the reading of the message was soon succeeded by one of bewilderment.

"How are we ever going to find out what it means?" demanded Willie. "We can keep juggling letters around until we get them into the proper combinations to make words out of them. But here we've got the words. And they don't mean anything to us. And I don't see how we're ever going to find out what they do mean. We couldn't juggle words around, too, could we, Captain Hardy?"

"No, Willie. There is no use trying that. The spies know what the words mean, all right enough. And nobody else does, unless he has the key to the code. All we can do is to guess what they mean."

"It will take some tall guessing," laughed Roy. "I don't even know what two of those words mean. Read 'em, Willie—those two long ones."

Everybody laughed. "B-A-L-A-K-L-A-V-A-N R-E-N-D-E-Z-V-O-U-S," spelled Willie. "They've got me stopped, too. What do they mean, Captain Hardy?"

"Balaklavan evidently is an adjective referring to Balaklava. Does any one of you remember that word? You've had it in history."

"I know," said Henry. "That's where the Light Brigade made its famous charge in the Crimean War."

"Good," said Captain Hardy. "That's exactly right. So that word evidently refers to a famous battle-ground. Can it be that we have stumbled on a diplomatic message instead of one meant for these spies? Could it be that this message has anything to do with the situation in the Balkans, I wonder?" and Captain Hardy began to turn the matter over in his mind.

"You didn't tell us what that other word meant," said Roy.

"Oh!" said the captain, with a smile. "That's a word of French origin that means meeting-place. Balaklavan meeting-place, Balaklavan meeting-place," repeated the captain. "This certainly must be an important message. The Chief ought to know about it at once. But I wouldn't dare telephone it. I'd have to take it to him."

"Maybe we could find out what it means," said Roy, "if only you would stay to direct us. Wouldn't it be great if the wireless patrol——"

"Roy," interrupted the patrol leader, "I know how you feel. You are very loyal to the wireless patrol. But this is a case that calls for loyalty to Uncle Sam first. The important thing is to get the message read—not to have it read by any particular persons."

"Let me take the message to the Chief," suggested Lew. "I am no good at this sort of thing, but I can carry a message as fast as anybody. Then you could stay here and help the others."

"Very well, Lew. Take a copy of the message as we caught it, and a copy of the cipher as we arranged it. The Chief will learn as much from them as he would from half an hour's talk. Now hurry."

In a few minutes Lew was speeding toward Manhattan with the message in his pocket, while the remainder of the wireless patrol were drawn up about Captain Hardy's desk, in earnest consultation.

"If only we had an up-to-date history," sighed Henry. "Then we'd know who the sovereigns are in the Balkans. All I know are Peter, of Servia, and it seems to me that he abdicated or died; and Ferdinand, of Bulgaria; and Constantine, of Greece, who abdicated in favor of his son Alexander; and the king of Roumania—isn't his name Ferdinand, too?"

"Then there is Charles, of Austria," suggested Captain Hardy, "and the Turkish Sultan, and King Victor Emmanuel III, of Italy. But I can't think of any King James. Well, we'll drop the kings at present and go on with the cipher. That brings us to three groups of letters—twenty-six, twenty-one, twenty-four. I know that code makers frequently use arbitrary groups of letters or figures to represent given words or ideas, but I haven't the slightest notion as to whether these figures belong together or are to be read separately. And as to what they mean, we can only guess. Since they seem to be in connection with some ruler and something about a Balkan meeting-place, they might refer to troops. You don't suppose the Germans are massing forces for another drive into Roumania or that part of Russia around the Black Sea, do you?"

For a little time there was complete silence, as each member of the party struggled to remember all that he had read about the situation in the near East. But none could throw any light on the matter.

"Well, we will drop the numbers and go on," said Captain Hardy. "That brings us back to the Balaklavan rendezvous. The word rendezvous plainly indicates some kind of a meeting. A number of people are going to get together somewhere. If the place indicated were not so evidently in the Crimea, I should think that the message might mean that these German agents we've been watching are summoned to a meeting somewhere."

Again there was a long pause. "Henry," said Captain Hardy suddenly, "to whom was this message sent, and by whom?"

"It had the same call signals that have always been used. It must have been sent from the motor-car station and it is intended for the same station or stations the other messages were sent to. But we don't know yet where they are."

"What would this motor-car driver, Sanders, be sending out a message about the Balkans for?" demanded Henry. "Is he connected with the German diplomatic corps as well as with the spy activities?"

"That's exactly what I was wondering about," replied Captain Hardy. "I can make nothing of it. The only thing I can understand is the last part of the message—'nine sure.' Somebody is to meet somebody somewhere at nine o'clock sure."

"If they meet at the Balaklavan rendez—— What's that word? I can't remember, Captain Hardy," said Roy.

"Rendezvous."

"Well, if somebody is to meet at some place at nine o'clock, the place can't be in the Balkans—not if the people who meet are the persons who received this message."

"You're right, Roy. And they couldn't meet in Europe, or even very far away in the United States, for," he continued, glancing at his watch, "it is already long past luncheon time."

"Well," said Henry, "there wouldn't be any sense in telling these spies about a meeting in the Balkans, anyway. So the message must be intended to call them to a meeting themselves."

"It must be so," assented Captain Hardy. "And if it is so, the situation is serious. Why should they want to meet? And why should the need be so urgent that they can't wait to send their message by safer channels, but fling it out into the air for anybody to pick up and read, if he has brains enough to do it? Hello! Here's Lew back again." And turning to the new member of the group, the leader said, "What did the Chief think of your message?"

"He was as puzzled as we were. He said his cipher experts were as busy as they could be with wireless messages of the utmost importance that the Germans had sent from Brazil to Berlin and that government operators had intercepted. But just as soon as he can get a man who knows anything about ciphers and codes, he will put him at this job."

"Then it's all the more important that we should unravel this thing ourselves. If something is to be done at nine o'clock, we haven't a moment to lose."

Hastily they ate their luncheon, then filed back to their living-room, where lay their maps, books, guides, and other equipment.

"We had better clear off these tables and desks," said Captain Hardy, "so that we shall have plenty of desk room. Suppose you pile these books on that book-shelf there, Henry. And you, Willie, put those maps on the mantel over the fireplace."

Henry gathered up a huge armful of books and hastily dumped them on the book-shelf indicated. They slid down into a heap, but none fell to the floor. Henry, in his usual careful manner, began to set the books to rights.

"Never mind that now," exclaimed Captain Hardy. "That can wait until we have more time."

Willie, meanwhile, was hastily stacking maps on the mantelpiece. He did not bother to fold them up, but put a weight on them and let the sheets hang down toward the floor. In no time the desks were cleared, and the little group soberly seated before them.

"You've taken away the paper with the message on it," said Captain Hardy to Henry.

Henry started for the book-shelves, but Willie, who sat nearest the shelves, was there almost before Henry was out of his chair. He scanned the heap of books, looking for the missing paper.

"There it is, under that Bible," he muttered.

He lifted off the superimposed books, and shoved the Bible to one side. The books began to slide, but Willie stopped them before they poured down to the floor. The Bible he caught on the very edge of the shelf, its covers open. He thrust the book back, seized the paper, and returned to his seat.

For perhaps an hour the little group worked on. Sometimes each labored in silence, busy with his own thoughts. Again there was eager discussion, as one or the other advanced some theory or idea as to the meaning of the message. Then silence would come again. So the hours rolled by. In one of these pauses, Willie sat with closed eyes, turning the mystery over in his mind. But his brain was tired and other thoughts would creep in. Once he caught himself thinking of Camp Brady. Again he was thinking about the East River, and all the sights he had seen on a trip he had made up that stream into the Sound. Rigidly he brought himself back to his task. But presently his attention wandered again. Now he was thinking about the book-shelf and the volume he had caught as it was slipping to the floor. And then, as though a flash of lightning had suddenly illuminated a dark place in his brain, he saw the words on the open page of the book—words that in his haste he had barely glimpsed, but that now came vividly to his mind:

TO THE MOST HIGH AND MIGHTY PRINCE

JAMES, By the Grace of God King of Great Britain, etc.

In another instant Willie was on his feet. "There's one King James that we didn't think of," he said, "the King James of the Bible."

His fellows laughed. "He's dead," said Roy.

But Willie paid no attention to the comment. His look was centred on his captain's face. And his captain's face was worth watching. Over it came that eager look that always marked his countenance when he got new light on a problem.

"Willie," he said, "I can't see the connection offhand, but it may well be that there is one. Can anybody think of any connection between King James and Balaklava and these spies?"

Nobody could. "The only thing that King James is remembered for," continued Captain Hardy, "is this very Bible—the King James' version, as we call it, in contradistinction to the Revised version. But I don't quite see how we can connect him with the rest of the message. Read the message over again, Henry."

When Henry had read it, Roy said, "If it said Matthew, or Psalms instead of King James, you would think that it was a text."

Captain Hardy leaped to his feet. "Stupid!" he cried. "Why didn't I see it before? Of course it's a text. Bring me the Bible. King James, 26, 21, 24," muttered Captain Hardy, as Roy placed it before him. "That must indicate the book, chapter, and verse."

He turned to the table of contents and began to count the books of the Bible. "Ezekiel," he announced, when he reached twenty-six. "If our theory is correct, this message refers to Ezekiel 21, 24. We'll soon know whether we're right or not."

His fingers trembled as he turned the pages, so eager was he. He found Ezekiel, turned to the twenty-first chapter, and ran his shaking finger down the columns until it rested on the twenty-fourth verse.

"Listen," he said, and his companions scarcely breathed as he read: "'Therefore thus saith the Lord God, Because ye have made your iniquity to be remembered, in that your transgressions are discovered, so that in all your doings your sins do appear; because, I say, that ye are come to remembrance, ye shall be taken with the hand.'"

For an instant complete silence followed the reading. Then Captain Hardy said, "Willie, you've solved the riddle. And it is just as I feared. The Germans have been alarmed. They know that they are detected. Now everything is plain enough—in a way. They had to warn all the members of the gang and they hadn't time to send messages. So they took a chance on the wireless. But they used a new cipher and resorted to a code. The use of the word 'rendezvous' indicates to my mind that they intend to flee. They're going to meet at the 'Balaklavan rendezvous' at nine. We've got to find where that is and get the secret service men there in time to nab them. And the afternoon's almost gone already."

Captain Hardy pulled out his watch and groaned as he looked at it. "We've got to watch these spies, too," he said. "Above all things we mustn't let them get away from us. If we can't find out where the Balaklavan rendezvous is any other way, we can trail these fellows to it."

Then the leader of the scouts turned to Lew. "Hustle down to the pine tree," he directed, "and watch the hawk's nest. It may already be too late. But if anybody is still there and comes out, trail him no matter where he goes. You can get into touch with me by telephone. Meantime, I'll communicate with the Chief."

Lew hurried away and Captain Hardy left the room to telephone. He came back with a white face.

"The Chief hasn't a man available," he reported. "All his men are watching some plotters who are trying to burn grain elevators and fire shipping. He says it's up to us and the police. So I called Police Headquarters and two detectives will be sent here at once. Pray Heaven they come in time."

Hardly had he finished speaking before Lew burst into the room. "Captain Hardy," he cried, "I was too late. Just as I reached the pine grove, I saw the spy running down the slope. He was a quarter of a mile away. I ran after him. But before I got near the shore he stepped into a motor-boat that was waiting and away he went. There were three other persons in the boat, and I am sure one was the grocer and one his boy. I had no way of following them, so I came straight back."

Just then the door-bell rang. Their hostess announced two men to see Captain Hardy. And the two detectives entered.

"Too late," groaned Captain Hardy. "The birds have flown. And we do not know where they have gone."



CHAPTER XIX

THE ENEMY ESCAPES

Evidently the detectives were little interested in the case. They asked a few perfunctory questions and went away without making any effort to intercept the fleeing motor-boat.

"They remind me of those state police at the Elk City reservoir," said Roy indignantly, "They don't take any interest in anything they don't do themselves. Or maybe they think the matter isn't worth bothering with because we're only boys."

"No, Roy," explained Captain Hardy, "I think it must be because we're working with the secret service. The police and the secret service are as jealous of each other as two cats; and the police don't want to do anything that will bring any credit to the secret service. They might have been able to do something to intercept that motor-boat. But I don't know what we can do. What was the boat like, anyway?"

Lew was able to give a good description of it; but evidently all distinguishing marks had been removed from it. It was a craft of perhaps thirty-five feet, slender, of light draft, and quite certainly built for speed. There was no name at either bow or stern, and the boat was painted a muddy gray that made it almost invisible at a little distance, so well did the color harmonize with the color of the harbor waters. Lew had watched it until it was almost out of sight; and all he knew was that it had started straight out through the Narrows, as though bound for the ocean.

"It looks at first glance," said Captain Hardy, "as though they were going to sea; but they couldn't go far in that craft. Perhaps there is some larger vessel there that they hope to reach."

He turned the idea over in his mind for a time. "I think it more likely that they are heading for some point on land," he said. "They are so clever at deception that that is most likely to be the case; and if it is, they may not even be going in the direction they are headed for. It will soon be dark. Then they could double back unseen. It's my idea that Newark ought to be a good refuge for them. It's a pretty big place, and it's full of German sympathizers—and they can reach it the way they're going. All they need to do is to keep right on around this island. That will take them to Newark Bay. I wonder if that isn't what they're up to, anyway?"

Willie went over to the mantel and brought a large map that showed all the waters of the region. He spread it out on the table and the group gathered around it, shoulders together, heads bent low.

"They might be making for Raritan Bay or Jamaica Bay," suggested Henry.

"Yes," replied Captain Hardy, "but I don't think it likely. Quite evidently they fear pursuit, and they will know that they are safest where boats are most numerous. And I should think that would be in Newark Bay, although I don't really know."

"They could coast along the shores of New Jersey," said Henry, "or of Long Island. What would they be most likely to do?"

"Ah!" replied Captain Hardy. "That's the very question. You know what Sherlock Holmes used to say: 'Eliminate the impossible, and whatever remains, no matter how improbable, is the truth.' I think that we can eliminate the possibility of their going to sea. That is practically impossible—unless—unless—there's a ship out there waiting for them. If this were England instead of America, I'd say that's exactly what was afoot: that there was a German boat somewhere offshore waiting for them. But the possibility of there being such a ship here is so remote that we can dismiss it."

"If they aren't going offshore, where are they going?" demanded Lew.

Everybody laughed. "That's what we've got to find out," replied Captain Hardy.

"I don't see how," said Lew hopelessly.

"No more do I," rejoined their leader, "but we'll have to start with what clues we have and try to follow them. All we know is that this motor-boat is outward bound through the Narrows and presumably is going to be at the Balaklavan rendezvous at nine o'clock."

"I wish we had a Light Brigade to send after them," sighed Henry, and as the others laughed, he began to quote what he remembered of Tennyson's lines that have made the name of Balaklava immortal:

"'Into the jaws of death, Into the mouth of hell Rode the six hundred.'"

Long ago dusk had come. The lights were lighted and the little group of scouts still clustered about their maps, searching vainly for a clue. Their hostess came to call them to dinner.

"I am sorry," said Captain Hardy apologetically, "but we are at work on a very grave matter and cannot possibly stop for dinner. Could you conveniently send us up some coffee and sandwiches?"

So, while they munched their sandwiches and sipped their hot coffee, the members of the wireless patrol continued their search for the missing clue. Occasionally Lew, more restless than his fellows, strolled over to the window and stood gazing out over the harbor, with its entrancing lights.

"There goes the Patrol," he called out suddenly, as a boat bearing the distinctive lights of the police department slipped down the Narrows, while he was at the window.

Captain Hardy gave an exclamation of annoyance. "Why didn't I think of that boat?" he said savagely. "We might have been able to follow the motor-boat if we could have gotten the Patrol here. For all we know, she may have been near at hand. And she is equipped with wireless, too. Well, it's too late now." Then bitterly he added, "The man who ordered the charge of the Light Brigade wasn't the only one who blundered."

"Is there any place near New York," suddenly demanded Henry, "named Balaklava or Crimea or anything else that suggests Balaklava?"

"Get that atlas from the book-shelves and see, Henry," replied Captain Hardy. "Look through the list of towns, rivers, lakes, etc. And you, Willie, study the map a while. That seems to be your forte. You may find something to suggest Balaklava to you."

Willie laid the map squarely on the table, and while Henry pored over the atlas and the others talked, and thought at intervals, he began a systematic survey of the map. And naturally he began in the region of the Lower Bay, toward which the motor-boat had disappeared.

Minute followed minute. Dusk turned to deep darkness. Captain Hardy opened and shut his watch in desperation. Swiftly the time was drawing near for the meeting of the spies, and the wireless patrol had not only failed at the critical moment, had not only allowed the enemy to escape, but had lost all track of them. It was a bitter thought and Captain Hardy tried to shut it out of his mind and centre attention on the problem in hand. Henry was still poring over names. Willie had finished his methodical examination of the Lower Bay and was working his way northward. He followed the boundaries of the harbor up through the Narrows and along the Jersey shore, then pursued his quest throughout the length and breadth of Newark Bay. But he found nothing suggestive of Balaklava. Back to the Bay he traced his route, then slowly traversed its waters. Past Bayonne, past Bedloe's Island, past Jersey City, and up the Hudson his pencil slowly moved, as he surveyed every name and looked at every turn and angle of the shore. Then he came back to the eastern side of the Narrows and went north along the Brooklyn shore. Past the Erie Basin, past Governor's Island, past the Brooklyn Bridge, past the Navy Yard, past Blackwell's Island, past Ward's Island, past Hell Gate, with its swirling currents, and on into the Sound, he traveled in imagination, examining every point and word on the map, but he saw nothing suggestive.

The minutes crept on. Eight o'clock had already struck. Captain Hardy was in a fever of anxiety. He could no longer sit still, but was pacing the floor. Lew, utterly hopeless of helping, stood at the window, looking out over the myriad lights of the harbor.

"There's the Patrol," he said. "She's coming back up the Narrows."

"If we only knew where to go, it wouldn't be too late yet," said Captain Hardy in a tragic voice. "It is awful to think that we have failed." In an agony of mind he began to pace the floor.

Henry had finished his perusal of the atlas and was thinking desperately over the problem. "I'd gladly go where the Light Brigade went," he muttered, "if only it would take us to those spies." And again he began to quote:

"'Into the jaws of death, Into the mouth of hell Rode the six hundred.'"

Hardly had he finished, when Willie gave a loud cry. "Hell Gate!" he almost shrieked. "That's where they are going to meet."

Captain Hardy stopped abruptly in his walk. The flush of hope crept into his cheek. "It's far-fetched," he said, "but it may be. It's the only chance we've got. Can we make it in time? Where's the Patrol, Lew?"

"Right there, sir; almost out of the Narrows."

"Quick, Henry. The wireless."

Henry rushed to the wireless room. Captain Hardy strode after him. The others followed. With eager, skilful fingers, Henry adjusted his instrument and began to flash out the call for the police-boat.

Almost at once he got an answer. As Henry wrote down the letters, Captain Hardy leaned over his shoulder, his eyes fastened on Henry's pencil.

"Tell them the secret service needs them at the landing at once, Henry. Tell them to hurry."

Then, while Henry was flashing his message into the night, Captain Hardy ran to the window to see what the Patrol would do. On and on it went, as though it had no intention of stopping, and cold beads of perspiration stood out on Captain Hardy's forehead, and he clasped and unclasped his hands in his excitement. On went the boat. Captain Hardy tore back to Henry's side.

"What do they say?" he demanded.

"They're coming, sir."

Again the captain stepped to the window. The little steamer was just beginning to turn.

"Get your hats and coats, quick," ordered the leader.

In a second the scouts were ready. In another, the little party emerged from the house and started pell-mell down the hill in a mad race to reach the landing before the police-boat got there.

Boat and boys touched the wharf at almost the same instant, and Captain Hardy's party leaped aboard before the steamer had entirely lost her headway. An officer stood at the gunwale, peering through the dark at the figures that swarmed aboard.

"I'm Lieutenant Gavigan, in command," he said, advancing toward Captain Hardy. "Are you the party that called us?"

"Yes," replied Captain Hardy.

A look of astonishment came over the lieutenant's face. "Your wireless said we was wanted by the secret service," said the puzzled lieutenant, "but these boys do not belong to the secret service. And I don't know you, either."

"I will explain everything," said Captain Hardy, "but make haste. We're after German spies that are to meet at Hell Gate at nine o'clock. Crowd on every ounce of steam you can."

"Hell Gate!" said the lieutenant sarcastically. "And do you think I'm going to take you to Hell Gate, just on your say-so—you and a crowd of kids I don't know from Adam? What do you think would happen to Lieutenant Gavigan if he went gallivantin' round the Bay without orders on joy rides like that? Nothin' doin'."

Captain Hardy smothered the indignation he felt, and began to explain courteously. "Lieutenant Gavigan," he said, "I am Captain Hardy of the United States Medical Reserve Corps and these boys are members of the Camp Brady Wireless Patrol. Last summer we did the wireless work for some of the Pennsylvania troops guarding public works, and in the course of our duties were fortunate enough to detect and capture some German spies who were endeavoring to blow up a great reservoir and cause another flood like that which wiped out Johnstown. For the last few weeks we have been helping the United States secret service keep track of German spies in New York, for, as you no doubt know, the secret service is short handed."

"Short handed," sneered the lieutenant. "Yes, and short minded, too, to be employin' a parcel of kids. But that's about as much sense as the secret service has got. If they want any spies caught, why don't they call in the cops? We'd catch 'em soon enough."

Captain Hardy choked down his resentment and went on. "We're not making any boasts as to our abilities, Lieutenant Gavigan," he said, "but we are doing all we can to help and the secret service thought well enough of us to put us to work."

The police officer looked the captain over critically. "How do I know you are what you say you are?" he asked. "Where are your credentials?"

A sudden fear smote Captain Hardy. Were all their efforts to come to naught? Were the treacherous spies to get away, now, when it seemed that they might yet be apprehended?

"We have never thought credentials would be necessary," he said, "and we have overlooked the need of providing ourselves with them. But we can satisfy you fully. Only hurry, Lieutenant, hurry."

"And where should I hurry?" the latter asked truculently. "You don't think I'm goin' to risk my head takin' the likes of you on a joy ride to Hell Gate, do you? Nothin' doin'. You come ashore and tell the captain who you are and what you want, and if he says Hell Gate, why, you'll get there, and if he don't, you won't. And that's all there is to that."

Very evidently it was useless to argue with the stubborn lieutenant. In despair Captain Hardy turned aside, desperately thinking how to meet the situation. Argument, he saw, was of no avail with this type of man. Force would have to be used. But what had he to offer that would impress the man?

"Captain Hardy," said Roy, slipping up to his commander, "would our police cards help any?"

"The very thing," said Captain Hardy. "I had forgotten that you boys had them."

Captain Hardy hastened back to the commander of the Patrol. "Lieutenant Gavigan," he said sharply, "there are more ways than one a policeman can lose his head. One is by being a fool. Your Commissioner is keenly interested in this work of ours and is giving us all the assistance he can. Each one of my boys carries his personal permission to go where he chooses. Roy, show this officer your pass."

Roy produced his police card, and the three other boys followed his example.

"Those cards were given to my boys by the Commissioner in person," said Captain Hardy impressively. "He is keeping in close touch with this work. I should not want to have to report that you blocked our efforts and made it possible for these spies to escape."

The change in Lieutenant Gavigan was remarkable. "Crowd on all the steam you've got, Jim," he shouted to the engineer. Then turning to Captain Hardy, he said, "Why didn't you tell me you was on police business? I'll send a wireless message at once for instructions."

Captain Hardy raised his hand in protest. "Impossible!" he said. "If the Germans should pick it up, everything would be lost. Our success depends wholly upon the speed and secrecy with which we travel. How much longer will it take to reach Hell Gate?"

"A half an hour, anyway," said the lieutenant, who was beginning to look worried. Then he added, "I'm takin' an awful chance, goin' up there without orders."

"And you're taking a worse one if you refuse to go," rejoined Captain Hardy sternly.

The lieutenant wavered. Captain Hardy strode into the cabin and seized a piece of paper. Lieutenant Gavigan, curious, followed him. Rapidly Captain Hardy wrote a message on the paper.

"Send that to your Commissioner," he said, handing the completed message to the commander of the Patrol.

Lieutenant Gavigan ran his eyes hurriedly over the paper. "Captain James Hardy, M. R. C.," ran the message, "and patrol of boys request immediate assistance. Everything at stake. Send instructions at once."

The lieutenant looked relieved. "The Commissioner won't be at his office at this hour," he said, "but they'll know where to reach him."

"Then rush it," said Captain Hardy, "and make every bit of speed you can."

He stepped out into the night again. Overhead myriad stars twinkled brightly. The little craft was vibrating from stem to stern under the rapid revolution of her engines. She was ploughing through the water, throwing up a great white wave on either bow. On all sides of her vessels were coming and going on their usual missions of peaceful industry. Millions of lights twinkled in the great buildings of the city and in the factories that lined the water-front. But Captain Hardy had no eye for the beauties of the night or the swelling waves or the stimulating harbor scene. He could think of nothing but the work ahead of him, of the rendezvous in the darkness at Hell Gate. The little steamer, ploughing her way through the water, seemed to Captain Hardy to be almost motionless, so keen were his fears that he would be too late. He pulled out his watch and groaned. The boat was well into the East River, but it was already almost nine o'clock. In agony of mind he began to pace up and down the deck.

"Got an answer," said Lieutenant Gavigan, suddenly coming out of the cabin, and he thrust a paper into Captain Hardy's hand.

The latter stepped toward the light and read it. "Give any assistance requested," it read. "Thank goodness, that's settled," muttered Captain Hardy.

Then he turned to the lieutenant, who was now more than ready to oblige. "Can't you get a little more speed out of her?" he demanded.

"I'll try," said the boat's commander, and he strode off to the engine room.

Past the Brooklyn Bridge, past the Manhattan Bridge, past the Navy Yard, past factories and offices and great rows of tenements, the little police-boat sped on. But the hands of Captain Hardy's watch sped faster. Past Blackwell's Island, with its long prison buildings, past the little lighthouse at its northern end, past the darkened area of the East River Park, on toward the blackness of Hell Gate with its frightful swirling waters, rushed the speeding craft. And now, drawn by a common interest, boys and men alike crowded the bow, and policemen and scouts stood in a close knot, gazing eagerly ahead into the darkness.

A motor-boat suddenly shot across the path of the Patrol. "Halt!" cried Lieutenant Gavigan, seizing a megaphone. The motor-boat came to. Lieutenant Gavigan was about to stop to examine it.

"Go on," said Captain Hardy tensely. "That's not the boat—and there's only one man in it anyway. We're after a gang."

Darker became the way. The river broadened. The waters grew troubled. High above loomed the great arch of the new railroad bridge over Hell Gate. A sailing craft drifted silently toward them. Lieutenant Gavigan looked questioningly toward Captain Hardy. The latter shook his head.

Again he drew forth his watch and held it close to his face. "Nine ten," he said, in a voice that shook with emotion.

On rushed the little steamer. It began to turn its nose toward the wicked waters that gave the region its name. Then it ploughed into the swirls and headed for the smooth reaches beyond. No craft of any sort could be seen.

"We'll have to go through," said the lieutenant. "We can't turn here."

The boat passed under the great bridge and on through the seething rapids. It ran on for a little distance, then circled and swung back. Again it passed through the angry waters, then made a wide circuit, steaming slowly along the land, while those aboard searched the darkness, peering into every curve and indentation of the shore, to try to spy out some sign of life. Tugs were shunting car barges, and an occasional steam craft passed, but nowhere was there a sign of a motor-boat or of the fugitive Germans.

A great doubt came into Captain Hardy's mind. Could it be that after all they had been on a wild-goose chase? He had thought the connection between Hell Gate and the Balaklavan rendezvous far-fetched. But it had been the one chance left. They had tried the theory out and they were wrong. The wireless patrol had not merely lost the Germans. They had lost all trace of them. They had failed in the crisis.



CHAPTER XX

A CLUE FROM THE AIR

Slowly the little police-boat finished her circuit, nosing into every dark nook and spying out every black corner; but blacker than either the night or the water was the gloom in the hearts of Captain Hardy and his fellow members of the wireless patrol. With bowed head the disappointed leader turned to the commander of the boat, to tell him to return to his dock. But Captain Hardy was too loyal to his fellows, too resentful of Lieutenant Gavigan's remarks about them to indicate by word or act that he thought they had been on a wild-goose chase. So he said simply, "We were too late, Lieutenant. They have given us the slip. But none the less I thank you for your assistance."

Then he turned aside and stood peering gloomily into the dark waters, that reflected the exact shade of his own mind. Appreciating better than his youthful companions the full extent of the disaster that had befallen them, he could not, for the time being, summon up his usual fortitude or see any hopeful prospect. Now that the spies knew that they were discovered, he felt sure that they would never risk the sending of another wireless message. And a wireless message was the sole clue by which his little patrol might once more pick up the trail of the fugitives.

But Captain Hardy's disappointment was no whit keener than that of his fellows, nor his sufferings any more poignant; yet with the buoyancy of inexperienced youth, hope was not entirely crushed in the heart of any one of the young scouts. So absolute was their faith in their leader, so astonishing had been the good fortune that so far had attended their efforts, that each felt that in some way this present disaster would yet be retrieved. And with hope as a motive power, each began, in a manner true to his character, to attack the problem that confronted them, to get ready for further service. It was a splendid example of the spirit of "never say die" that their leader had drilled into them—an example that he would be quick to follow, once the shock of disappointment had passed away.

Lew, hopeless of solving the puzzle of the spies' disappearance, was thinking of how the scouts should equip themselves if they should be called upon for a land pursuit; for at following trails and taking care of himself in the open he had no superior in the wireless patrol. Roy, keen minded as a Sherlock Holmes, was turning over in his mind the problem of the spies' escape, trying to reason out what their line of action would be in the immediate future. Willie was examining a mental landscape to decide the same question. With that wonderful facility of memory he had acquired by hours of practice at Camp Brady, he now called up the maps of the neighboring waters he had been studying; and in his mind's eye he could see every point and indentation of the shore-lines, every arm of water, every inequality of the land as pictured on the contour map, and the principal roads of the region. And he was asking himself what a party of fugitives in a small boat would naturally do.

Henry, eager as always to learn more about the wireless, had ingratiated himself with the Patrol's wireless man and was eagerly examining his instruments and plying him with questions. At first the operator answered with good-natured tolerance as one replies to the queries of a child. But when he saw how much Henry actually knew, and found that though he was only a boy he had already acted as operator at a government wireless station, he fell into an earnest discussion about the possibilities of wireless in police work—for in New York the police wireless was still in an experimental stage. Then he permitted Henry to clamp on the receivers and listen in.

Henry welcomed the opportunity, for in all the weeks they had been watching the Germans, the wireless patrol had hardly had an opportunity to listen to the myriad voices in the air. They had had to shut out all other sounds and tune down to the low lengths used by the Germans—and by nobody else. They had been like spectators at the opera with their ears plugged to shut out the music.

Now, as Henry eagerly listened in, he caught a sharp, whining note that vibrated powerfully in his ear. "There's the Navy Yard calling," he said, and a deep frown passed over his face, for it made him think of submarines and the failure of the wireless patrol. For a moment he tuned to a short length and listened for a spy message, as he had done so many times before.

"That's the Waldorf-Astoria talking," said Henry a moment later, and he copied down the message and shoved it over to the police operator.

Then followed press despatches—stories of land and sea, of fires and battles, of shipwrecks and the arrest of a spy. And again Henry scowled and slid his tuning-coil and briefly listened in at lower range.

Down the river ploughed the little steamer, repassing, one by one, the landmarks it had passed on its trip northward. As it steamed along and the meaning of their failure became more apparent to the young scouts, they became gloomier and gloomier. But Henry, exulting at the opportunity to handle such an outfit, almost forgot their failure, and drank in eagerly the gossip of the night. So engrossed was he, that he was startled when he heard the order to slacken speed, and heard his captain say, "Well, here we are, boys."

Reluctantly he removed the receivers. Then, as an after-thought struck him, he clamped them again to his ears, tuned his coil to a low length, and strained his ears in one last search for a forbidden voice in the dark. For a moment he sat listening vainly. Then, with unwilling fingers, he began to take the clamps from his head. But suddenly he jammed the receivers back on his ears and sat tense.

"Hurry up, Henry," called Captain Hardy. "We're waiting for you."

"Hush!" said Henry, lifting a warning hand. Then he sat rigid, bending eagerly forward. In his ear a call was sounding. It was the old familiar call of the motor station. He seized a pencil and began to write. A moment later he jumped to his feet and went rushing after his captain.

"Here!" he called, thrusting a paper into Captain Hardy's hand. "The motor-car station just sent this message."

"The motor-car station!" exclaimed Captain Hardy, in astonishment. "Then Sanders can't be aboard the motor-boat. The Chief said he had him covered so closely that he could not escape—and evidently he couldn't." A moment later Captain Hardy stood frowning, trying to puzzle out the meaning of it. "I don't see how he could have sent a message," he continued, "if he is so closely watched that he couldn't get away."

"Perhaps the message will tell us," suggested Roy.

"Right again, Roy," said Captain Hardy. "We'll hurry to the office and decipher it."

On the run they made their way to the subway station at Bowling Green. They caught a north bound train and shortly afterward swarmed up out of the subway and made a rush for the secret service offices.

With hardly more than a word of greeting they drew up at a table and laid the paper with the message before them.

"Forty," said Captain Hardy, counting the letters. "If they use the same cipher they did last time, that'll make five columns of eight letters each." Rapidly he set down the letters in the order indicated, thus:

T T E N R H A S E Y G Y U R A I L O E B N T V R O D C Z E H I A E V C M X D E E

Then slowly he read off the message: "ECHO—BAY—REVERE—RENDEZVOUS—EXACTLY—AT—MIDNIGHT."

With a cry of joy Captain Hardy leaped to his feet. "We've got another chance," he said. "Sanders must be going to meet them at Revere Rendezvous—wherever that is." Then, turning to a man at the next desk, he inquired, "Where is Echo Bay?"

"At New Rochelle," said the agent. "That's where Fort Slocum is."

"Fort Slocum!" cried Captain Hardy. "This may be even more serious than it seems. Can this man be spying on the fort, too? How far is New Rochelle from here?"

"Eighteen or twenty miles."

"Can we get there by twelve o'clock?"

"Sure. Why?"

"The spies we are after are to meet at Echo Bay, Revere Rendezvous, at midnight. Are you sure that we can get there?" Then he glanced at his watch. "It's already long past ten."

The Chief was still at the office. The agent went to consult him, and came back for details. Captain Hardy stepped into the Chief's private office and made the entire situation plain. The Chief sat like a cake of ice, a thinking machine immovable and unmoved, listening to the recital.

"How many men have you here?" he asked his subordinate, the instant Captain Hardy had done talking.

"Four."

"Two of you go by automobile, two by motorboat. Divide these boys and take half with each party. Let those who go by land approach the meeting-place on foot and hide. The motorboat must come in behind the spy boat and cut off retreat. Be sure you are armed."



CHAPTER XXI

THE CAPTURE OF THE SPIES

Without a moment's delay the party that was to go by boat, including Henry and Roy, rushed off to the dock where the secret service had a motor craft of the racing type, capable of making tremendous speed. Almost as quickly the other party found itself seated in a powerful touring-car, speeding northward. Captain Hardy, Willie, and Lew were in the car, together with the two agents and the driver, who was likewise a secret service man.

Up Third Avenue rolled the big automobile, dodging wagons, shooting past motor-cars, darting by trolleys, its horn shrieking an almost unceasing warning as it charged onward at the very top of the speed limit. Never had Willie or Lew ridden so fast in crowded thoroughfares, and time and again they held their breath as the big car rushed toward some obstacle in its path, expecting a crash. But under the skilled hands of the driver the great machine swept in and out, weaving its way through the traffic as an eel glides through water growths.

The first thrill passed, they turned to their captain and the secret service agents who were earnestly discussing the situation. Overhead the thunder of the elevated trains was such that at times they could hardly hear what the men beside them were saying.

"I am well acquainted with New Rochelle and the region of Echo Bay," said one of the agents, "but I never heard of any Revere Rendezvous there. However, the people of the town can doubtless tell us. We shall have time to make inquiries." And turning to the driver, he said, "Shove her to the limit, Jim."

Already the car was well up-town. Traffic had grown steadily less, and as steadily the driver increased his speed. Now they were rolling over the smooth asphalt at twenty miles an hour.

"No doubt they could tell us," replied Captain Hardy, "if there were any such place. But I fear that the name is one of the spies' own making," and he told the story of the Balaklavan rendezvous. "We think that meant Hell Gate," explained Captain Hardy. "The fact that the spies' motor-boat is now evidently on the Sound confirms that belief. But the name was far-fetched. It took us a long time to work it out. This new name may be equally obscure. We shall have to decipher it on the way."