to keep prisoners. Nearly all of the old châteaux had dungeons underneath them. Later, they were turned into wine-cellars." "Let's see it," said Bob. "I was never in one before.”

"Better not," his cousin warned. "The walls may fall in and bury you alive."

"Oh, if they 've stood all these years, I guess they won't cave in to-day," Bob retorted, entering the archway.

Egmont and Guy followed, for Bob's exploring curiosity was shared by them, and they were not going to stay behind on account of some fancied danger.

The archway opened into a long tunnel, whose walls were damp and musty. They had stumbled along this for some distance when they came to another short flight of stairs.

"I would n't go any farther," Egmont cautioned again. But Bob was already descending the stone steps, and at the bottom he called back: "Here 's another tunnel. Where does that go?"

"I don't know; but we 'd better go back."

"No, I'm going on."

Then Bob stopped suddenly and cocked his head to one side. "Listen!" he whispered. "I thought I heard a noise."

"No, it was Guy's foot kicking a stone,' replied his cousin.

Bob nodded, but remained listening. Then he found it was not so much a noise that had attracted his attention as a vibration of the floor on which they stood. It was so distant and muffled that it was scarcely perceptible, but when they remained perfectly still they could hearor feel it distinctly.

It was a series of jarring vibrations like the distant pounding of horses' hoofs on the earth.

"It comes from above us," Guy whispered, after a long pause.

"Yes, horsemen," replied Bob. "Do you suppose they have followed us, after all?"

They applied their ears to the walls and listened in silence for some time. The uncanny pounding continued, but strangely enough, seemed to come no nearer. Coupled with the darkness and the strange

ness of their position, it would have racked the strongest nerves.

"Let's go back," murmured Egmont. "No," was Bob's stubborn answer, "I'm going to find out what makes that noise. Come on.'

Egmont grumbled, but followed, and Guy, with even more reluctance, brought up the rear. Creeping stealthily along, using the right wall as a guide, Bob led the way in the darkness. To their great surprise, the muffled noises and vibrations increased as they proceeded, until finally Guy and Egmont were as eager as their leader to explore the mystery. There was something strange and uncanny about it that piqued their curiosity, even while it frightened them.

Bob stumbled along blindly, for the floor in many places was littered with sharp stones and fallen mortar. The tunnel curved to the right, and, instead of rounding it, he struck against one side.

"Look out!" he whispered. "It turns here."

The moment they turned the curve, the muffled vibrations became so clear and distinct that the boys stopped in tense surprise. Whatever it was, they were close upon the solution of the mystery. Their hearts beat rapidly while they listened.

"It's just ahead!" Bob whispered.

He started forward so eagerly that he tripped upon something in his pathway. The next moment he went plunging forward on hands and knees, landing with considerable force on the hard floor. With a grunt of pain and dismay, he lay there a moment, a little stunned by the fall.

"Are you hurt, Bob?" Egmont asked softly.

"No, not much. But listen! Where's the noise? Do you hear it?"

All three remained absolutely quiet and motionless, their ears vainly trying to catch the sound that had led them onward like a will-o'-wisp. But it was deathly quiet in the tunnel, and the vibration had absolutely ceased. The silence was so startling that they dared scarcely breathe for fear of breaking it.

CHAPTER VII

PRISONERS

THE puzzling quiet that followed Bob's mishap was further accentuated by a queer sensation that somebody else was with them in the narrow passage, and that they were being watched by eyes that could see them through the darkness. Or, if eyes could not penetrate the intense gloom, at least ears could hear.

The pounding noises that had drawn them onward, and had now mysteriously ceased, were undoubtedly of human origin. Not one of the boys attributed anything supernatural to them, though the idea. that they were caused by the pounding of hoofs on the earth above had long since been dismissed. They felt sure the sounds had come from somewhere in the underground passageway through which they had been crawling.

They waited a tense ten minutes, but nothing happened-not the slightest sound. indicated the presence of any one in the tunnel. Finally, Bob could bear it no longer.

"I'm going to strike a match," he announced. "There's nothing to fear. Suppose it's a German spy; he can't do any more than capture us, and we 've done nothing. Our presence here is n't a crime."

"No, but-" began his cousin, hesitatingly, and then stopped for lack of any good reason for objecting.

Bob accepted this as approval of his intention, and taking a match from his pocket, he struck it on the cover of the box. There was a brilliant flare which illumined the tunnel ahead; but it disclosed nothing but the moisture-dripping walls. When the wood of the match caught fire the light was dimmer, but steadier. Bob held it over his head to look around.

"There's nothing here," he murmured. "I'll go a little farther, and then strike another match."

But at this moment there came a sudden flash of light ahead that cut through the darkness like a searchlight, temporar

ily blinding and paralyzing them. Several dark forms shot forward, and before any of the boys could raise a hand to defend himself, they were borne to the earth and securely pinioned by powerful arms.

"Have you got all of them?" came a growling voice in front. "Be quite sure! Search the tunnel."

A series of lights flashed all around them, as dark figures leaped over the prostrate prisoners and began a hurried search of the passageway back of them. The lights and the figures gave a strange, uncanny aspect to the scene. In spite of their courage the boys trembled. They had no idea who the men were or their purpose there.

Their captors had trussed them up quickly, and put gags in their mouths so they could not speak. The lights disappeared around the curve in the tunnel, and for some time the darkness was as intense as before.

Five minutes later the men with the electric torches returned. "No one else," the first man reported.

"Then bring them in," replied the one who had spoken first.

In perfect silence their captors picked up the boys and carried them through the tunnel and into an underground chamber, which, as Egmont immediately recognized, and Bob suspected, had been the dungeon of the old château, and had been used later as a wine-cellar. It was a broad, moderately high chamber, hewn out of the solid. rock, the only entrance to it being that through which the boys had been carried. The iron door that had once guarded the passageway had long since rusted off its hinges, but a new one, made of timber and braced with rough-hewn logs, had replaced it.

When this door was closed, and a thick beam placed in front of it, a huge kerosene lamp, suspended from the middle of the roof, was lighted and several smaller ones along the walls. It was not a brilliant illumination, but enough for the prisoners to inspect their surroundings.

At first they were more interested in the men about them. If they were Ger

man spies, their dress did not indicate it. They were in civilian clothes-rough, stained jackets, trousers, and aprons; they had bearded faces and small, burning eyes, which constantly shifted from one of the prisoners to another.

The chamber was furnished in the strangest way. In fact, it might be said that it was n't furnished at all, for boxes were the only seats visible, and huddles of straw and blankets in the corners were the only signs of beds. There was a long table down the center, but it was littered with books and papers rather than with dishes and things to eat. A queer-looking machine stood in one corner, and rows of flat, shallow boxes were arranged near it. Not even Bob could make a guess as to their meaning.

The man who seemed to be the leader finally took a torch from one of his men and flashed it in the faces of the boys, studying their features under conditions more favorable to him than to his prisoners. He continued this for some time, frowning all the while.

"Boys!" he mumbled finally in disgust, "they're not spies."

"Don't be too sure of that," murmured another bearded companion. "Spies are spies, whether boys or men."

The leader again stared searchingly at them. Now that his captives were boys, and not full-grown men, a good deal of the fierceness left his face, and his eyes twinkled. "Who are you?" he asked, nodding at Bob.

"Robert Lane," was the prompt reply. "And that's my cousin Egmont d'Anethan," he added, speaking for them all. "And the other 's Guy d'Assches."

"Count d'Anethan's grandson?" queried the leader, indicating Egmont.

"Yes. If you've lived in Belgium, you ought to know him-everybody does; and I'm his American cousin."

The man's face changed slowly. The old fear and suspicion was succeeded by a look of friendliness. "Yes," he nodded; "I know Count d'Anethan quite well, and I've heard of his two grandchildren."

He began stroking his shaggy beard in

meditation. Then he asked, with a little return of his former suspicion: "What were you doing down here? What were you after in the tunnel?"

"Nothing, except to explore it," replied Bob, promptly. "Egmont said it led to the old dungeon of the ruined château, and I wanted to see it."

"Well, you see it now," was the smiling reply. He paused, and then continued: "It 's unfortunate that you stumbled in here. It puts us in a very difficult position. We don't want to hurt you or cause you discomfort, but for the sake of Belgium we have to do many things that we would not do at any other time. We have to consider the greater question of our country's welfare. Now, if we should release you, you would talk of what you had seen here, and-"

"Not if it's for the cause of Belgium!" interrupted Bob. "We can keep a secret as well as any one."

The man shook his head sagely. "It would be dangerous to let you go. A German spy might overhear you talking of it, and then-" he waved his hand expressively over his head-"that would be the end of all our work."

Bob glanced around the rock-hewn chamber and recalled the muffled pounding and vibration that had drawn them on in their explorations. His eyes rested on the machine at one side of the chamber, and the shallow boxes standing near it. There was something familiar in both, and for a few moments his mind was busy trying to piece together disjointed facts. Suddenly his face cleared. He looked up triumphantly.

"I know now what you 're doing down here!" he exclaimed, not realizing the effect the words would have on his captors.

"What!" demanded the leader in a voice that suddenly lost all its friendliness.

"That's a printing-press, is n't it?" Bob asked, "and those shallow boxes are type-cases. I was in a printing-office once, and-"

"Well, what of that?" asked the man, trying to appear indifferent.

"Nothing, except-except-"

"What?" snarled the other.

Bob hesitated to speak what was on his mind, but his suspicion had become almost a certainty, and it was impossible to hold it back.

"Don't you print 'La Libre Belgique' down here?" he asked. "Yes," he added triumphantly, "and you must be the editor of it. The Huns have set a big price on your head. They're looking everywhere for you. When I told the commandant I'd read in your paper about the American soldiers coming in big numbers, he nearly had a fit. He said to the lieutenant that your paper was the spy, and not I. That 's how I got off."

"What are you talking about?" cut in the man, frowning.

Bob, realizing that his disjointed remarks were not very enlightening, quickly related the series of events that had led up to his arrest, confident that the editor

of the only paper published in Brussels of Belgian origin would not betray him.

"Where did you get all your information about the Americans coming over, in such numbers? Was it just guesswork, or have you seen some of the English papers?"

"No, it was n't guesswork," replied Bob, slowly. "It came to me straight enough, and I know it's true."

"Who told you?"

Bob hesitated a second, and then replied, smiling, "The Vigilantes!"

"Vigilantes! Who are they? I never heard of them." Then, scowling, the man added: "Is this some boyish fooling? If so, this is no place for it. Whether you know it or not, you 've got yourself into a serious predicament. We can't let you go now. The fate of too many good men depends upon it. We must hold you prisoners until we can move to another hidingplace."

"B-z-z-z-z-z!"

That meant that the editor of the "News-Herald," the great New York newspaper, finger on buzzer, was calling Billy, the office-boy.

"Copy boy! Hurry up!" That was Pitts, the youngest reporter on the paper, to whom Billy was only hands and feet, calling him to rush the precious stuff Pitts had written.

"Hey, you! Bring me a ham sandwich! Move! You're as slow as they make 'em!" That was Kelly, head of the "NewsHerald" office-boys, addressing Billy.

As the three calls came at the same moment, there was no doubt in any one's mind as to where Billy was headed. But a fourth call reached him as he was hurrying by the elevator cage.

"Please, do you suppose the editor would see me just for a moment or two?"

Billy saw a timid young man with longish hair and dressed in a shabby suit. He had the air of expecting momentarily to be hustled to the street. Billy's heart went out to him. He knew just how the young man felt. Six months before, when Billy came to work as office-boy on the "NewsHerald," he felt exactly the same way. Every one but the editor barked at him, and the editor's push-button buzzed at him like an angry hornet. If Billy's father had not died; if Billy's mother did not need his small earnings to keep their home together; if Billy himself had not set his heart on becoming some day a reporter, he would have fled the first day he came to the "News-Herald." But he stayed on. Fortunately, he soon found that the bark of most of the men in the office was worse than their bite; indeed, the only reason they barked at him was that they were always in a hurry. Every one in a big newspaper office is in a hurry. The only people who made Billy's work uncomfortable were Pitts, the "cub" reporter, who liked having some one he could order about, and Kelly, the head office-boy.

So Billy turned to the timid young man.

"What would you like to see the editor about?" Billy asked kindly.

"I have an invention with which you can speak from a moving object to some one hundreds of miles away without the use of wires," the young man said eagerly. “My name is Phineas Wetherby."

"All right, I'll ask if the editor can see you," Billy said hastily.

He felt still more sorry for the young man now that he knew he must be one of those poor, queer "cranks" who haunt newspaper offices, but whom the editors never "see" because they are only cranks.

"Billy, take this paper to the city editor," the great man at the head of the paper said when Billy appeared.

"Yes, sir!" Billy said. "Please, will you see a poor young fellow who is outside and wants to talk to you?" Billy ventured. "He says he has an invention."

The editor did not even look up. "Tell Pitts to see him!"

With that the great man completely forgot Billy's young man.

Billy delivered the paper to the city editor, then went to Pitts.

"Mr. Morgan would like you to talk to a young man outside who wants to see him," Billy said.

Pitts knew if the editor referred a visitor to the youngest "cub" on the staff, the matter could not be of any importance. So Pitts called Kelly.

"See what that guy outside is like, and find out what he wants!" he said, with a bored air.

Kelly nodded and went out. Billy followed.

"Well?" said Kelly, surveying the young man, from his longish hair to his worn shoes.

The young man tried to explain. But Kelly's unfriendly look made it hard for him. Kelly went back to Pitts.

"He's a 'nut'!" He tapped his forehead. "Says he 's got some sort of a machine that'll talk a million miles away