With anxious hearts the Air Service boys ran on. There was no need to ask their way, for they had but to follow the throng toward the scene of the most recent exhibition of the Hun's frightfulness and horror.
As they drew near the Rue Lafayette, where Mr. Raymond had said he intended to stay while in Paris, the boys were halted by an officer on the outskirts of the throng.
"Pardon, but you may not go farther," he said, courteously enough. "There is danger. We are about to sound the alarm so that all may take to shelter. The Boches are raiding Paris again."
"We know it," said Tom. "But it is no idle curiosity that takes us on."
"No?" politely questioned the policeman.
"No. I am seeking my father. He wrote to me that he would stop in the Rue Lafayette, and I have not heard from him since. I was told that the last shell fell in that street."
"It did," assented the officer, "and it demolished two houses and part of another. Many were killed and injured."
"Then I must see if my father is among them!" insisted the young aviator.
"Pardon, monsieur, it is not possible. I have my instructions, and—"
He stopped, and for the first time seemed to become aware of the uniforms worn by Tom and Jack. Then the officer saluted as though proud to do it.
"Ah," he murmured. "Of the Lafayette Escadrille! You may go where you will. Only I hope it is not into danger," he said, as he drew aside for them to pass. "Pardon, I did not at first sense who you were. France owes you much, messieurs. Keep your lives save for her!"
"We will," promised Tom, as he hurried on, followed by Jack.
They came to the head of the street they sought, and, looking down it, beheld ruins greater than they had seen before. As the officer had said, two buildings had been completely demolished, and a third partly so, the wreckage of all mingling. And amid these ruins police and soldiers were working frantically to get out the injured and remove the dead, of whom there was a sad number.
Tom's face was white, but he kept his nerve. He had been through too many scenes of horror, had been too near death too often of late, as had his chum, to falter now, even though his father might be among those buried in the wreckage caused by the German shell.
"Do you know what number your father was to stop at?" asked Jack.
"Yes, I have his letter," Tom answered. "I'm afraid, Jack, it was in one of those buildings that have been blown apart."
"No, Tom!"
"I'm afraid so. But, even at that, he may have had a chance for his life. He may have been out, or, after all, he may not have arrived yet. I'm not going to give up hope until I have to."
"That's the way to talk, old man. I'm with you to the last."
They pressed on, and populace and officers alike gave way before them as they saw the uniforms.
"We've got to help!" declared Tom. "We must pitch in, Jack, and lend a hand here. The soldiers seem to be in charge. Let's report to the commanding officer and offer our services."
"But your father?"
"That's the best way to find him if he's in those ruins. Let us help get the unfortunates out. I hope I don't find him, but I must make sure."
Making their way through the press of people, which, under order of the police and military authorities, had begun to disperse in some small measure, Tom and Jack reported to the officer in charge, giving him their names and rank, at the same time showing their papers.
"We want to help," the lads told him.
"And I ask no better," was the quick response. "There are dead and dying under that pile. They must be gotten out."
And then began heart-rending scenes. Tom and Jack did valiant work in carrying out the dead and dying, in both of which classes were men, women and children.
The German beasts were living up to the mark they had set for themselves in their war of frightfulness.
Each time a dead or injured man was reached, to be carried out for hospital treatment or to have the last sad rites paid him, Tom nerved himself to look. But he did not see his father, and some small measure of thankfulness surged into his heart. But there were still others buried deep under the ruins, and it would be some time before their bodies, dead or alive, could be got out.
As the soldiers and police worked, on all sides could be heard discussions as to what new form or manner of weapon the Germans were using thus to reach Paris. Many inclined to the theory that it was a new form of airship, flying so high as to be not only beyond ordinary observation, but to be unreachable by the type of planes available at Paris.
"If we could only find a piece of the shell we could come nearer to guessing what sort of gun fired it," remarked Tom, as the two Air Service boys rested a moment from their hard, terrible labors.
"Do you mean if it was dropped from an airship it wouldn't have any rifling grooves on it?" asked Jack.
"That's it. A bomb, dropped from an aeroplane, would, very likely, be only a sort of round affair, set to explode on contact or by a time fuse. But if it was a shell fired from a long-range gun, there might be enough of it left, after the explosion, to observe the rifling."
"There isn't a gun with a range long enough to reach Paris from the nearest German lines, unless they have broken through," said Jack.
"Well, the last may have happened; though I should think we'd have got some word of it in that case. There'd be fierce fighting if the Germans tried that, and we'd rush reinforcements out in taxicabs as the Paris soldiers went out once before."
"Do you think then," asked Jack, as they went back, after their brief respite, to their appalling labors, "that they have a gun long enough to fire from their nearest point, which is about seventy miles from this city?"
"I don't know what to think," remarked Tom. "It seems like a wild dream to speak of a gun that can shoot so far; and yet reality is over-topping many wild dreams these days. I'm going to reserve judgment. My chief concern now, though of course I'm not going to let it interfere with my work, is to find my father. If he should have been in here, Jack—"
Tom did not finish, but his chum knew what he meant, and sympathized with his unexpressed fear for the safety of Mr. Raymond.
Digging and delving into the ruins, they brought out the racked and maimed bodies, and there was more than one whose eyes were wet with tears, while in their hearts wild and justifiable rage was felt at the ruthless Germans.
Ten had been killed and nearly twice that number wounded in the third shell from the Hun cannon.
From a policeman Tom learned that one of the two buildings that had been demolished was the number given by Mr. Raymond as the place he would stay.
"The place he picked out may have been full, and he might have gone somewhere else," said Tom. "We've got to find out about that, Jack."
"That's right. I should think the best person, or persons, to talk to would be the janitors, or 'concierges,' as they call 'em here."
"I'll do that," responded Tom.
Aided by an army officer, to whom the boys had recommended themselves, not only by reason of their rank, but because of their good work in the emergency, they found a man who was in charge of all three buildings as a renting agent. Fortunately he had his books, which he had saved from the wreck.
"You ask for a Monsieur Raymond," he said, as he scanned the begrimed pages. "Yes, he was here. It was in the middle building he had a room."
"In the one that was destroyed?" asked Tom, his heart sinking.
"I regret to say it—yes."
"Then I—then it may be all up with poor old dad!" and Tom, with a masterful effort, restrained his grief, while Jack gripped his chum's hand hard.
Tom Raymond, having gone through a hard school since he began flying for France, soon recovered almost complete mastery of himself. The first shock was severe, but when it was over he was able to think clearly. Indeed the faculty of thinking clearly in times of great danger is what makes great aviators. For in no other situation is a clear and quick brain so urgently needed.
"Well, I'm sure of one thing, Jack," said Tom, as they walked away from the fateful ruins. "Of those we helped carry out none was my father. He wasn't among the injured or dead."
"I'm sure of that, too. Still we mustn't count too much on it, Tom. I don't want you to have false hopes. We must make sure."
"Yes, I'm going to. We'll visit the hospitals and morgues, and talk with the military and police authorities. In these war times there is a record of everybody and everything kept, so it ought to be easy to trace him."
"He arrived all right, that's settled," declared Jack. "The agent's record proves that."
"Yes. I'd like to have a further talk with that agent before we set out to make other inquiries."
This Tom was able to bring about some time later that day. The agent informed the lad that Mr. Raymond, contrary to his expectations, had arrived only the day before. Where he had been delayed since arriving in Europe was not made clear.
"But was my father in the building at the time the shell struck here?" asked Tom. "That's what I want to know."
Of this the man could not be certain. He had seen Mr. Raymond, he said, an hour or so before the bombardment, and the inventor was, at that time, in his room. Then he had gone out, but whether he had come back and was in the house when the shell struck the place, could not be said with certainty.
But if he had been in his apartment there was little chance that he had been left alive, for the explosion occurred very near his room, destroying everything. Tom hoped, later, to find some of his father's effects.
"There is just a chance, Jack," said the inventor's son, "that he wasn't in his room."
"A good chance, I should say," agreed the other. "Even if he had returned to his room, and that's unlikely, he may have run out at the sound of the first explosion, to see what it was all about."
"I'm counting on that. If he was out he is probably alive now. But if he was in his room—"
"There would be some trace of him," finished Jack.
"And that's what we've got to find."
The police and soldiers were only too willing to assist Tom in his search for his father. The ruins, they said, would be carefully gone over in an endeavor to get a piece of the German shell to ascertain its nature and the kind of gun that fired it. During that search some trace might be found of Mr. Raymond.
It did not take long to establish one fact—that the inventor's body was not among the dead carried out. Nor was he numbered with the injured in the hospitals. Careful records had been kept, and no one at all answering to his description had been taken out or cared for.
And yet, of course, there was the nerve-racking possibility that he might have been so terribly mutilated that his body was beyond all human semblance. The place where his room had been was a mass of splintered wood and crumbled masonry. There was none of his effects discernible, and Tom did not know what to think.
"We've just got to wait," he said to Jack, late that afternoon, when their search of the hospitals and morgues had ended fruitlessly.
Meanwhile the French airmen had been scouring the sky for a sight of the German craft that might have released the death-dealing bombs on the city. But their success had been nil. Not a Hun had been sighted, and one aviator went up nearly four miles in an endeavor to locate a hostile craft.
Of course it was possible that a super-machine of the Huns had flown higher, but this did not seem feasible.
"There is some other explanation of the bombardment of Paris, I'm sure," said Tom, as he and Jack went to their lodgings. "It will be a surprise, too, I'm thinking, and we'll have to make over some of our old ideas and accept new ones."
"I believe you're right, Tom. But say, do you remember that fellow we saw in the train—the one I thought was a German spy?"
"To be sure I remember him and hismetzel suppe. What about him? Do you see him again?" and Tom looked out into the street from the window of their lodging.
"No. I don't see him. But he may have had something to do with shelling the city."
"You don't mean he carried a long-range gun in his pocket, do you, Jack?" and Tom smiled for the first time since the awful tragedy.
"No, of course not. Still he may have known it was going to happen, and have come to observe the effect and report to his beastly masters."
"He'd be foolish to come to Paris and run the chance of being hit by his own shells."
"Unless he knew just where they were going to fall," said Jack.
"You have a reason for everything, I see," remarked Tom. "Well, the next time we go to headquarters we'll find out what they learned of this fellow. You know we started the secret service agents on his trail."
"Yes, I know. Well, I was just sort of wondering if he had anything to do with the bombardment of Paris. You've got to look for German spies now, even under your bed at night."
The boys felt they could do nothing more that day toward finding Mr. Raymond. A more detailed and careful search of the ruins might reveal something. Until this was accomplished nothing could be done.
They ate a late supper, without much in the way of appetites, it must be confessed, and then went out in the streets of Paris. There seemed to be few signs of war, aside from the many soldiers, and even the bombardment of a few hours earlier appeared to have been forgotten. But of course there was grief in many hearts.
It was early the next morning, when Tom and Jack were getting ready to go back to the ruins in the Rue Lafayette, that, as they left their lodgings, they heard in the air above them the familiar sounds of aeroplanes in flight, and the faint popping of machine guns, to which was added the burst of shrapnel.
"Look!" cried Jack. "It's a battle in the air. The Huns are making another raid. Now we'll see how they bomb the city."
But it did not turn out to be that sort of raid. The German craft were flying low, apparently to get a view of the havoc wrought the day before. Possibly photographs were being taken.
But the French aeroplanes were ready for the foe, and at once arose to give battle, while the anti-aircraft guns roared out a stern order to retreat. It was a battle above the city and, more than once, Tom and Jack wished they could be in it.
"We'll have to get back to our hangars soon," mused Tom, as they watched the fight. "We can't be slackers, even if I can't find my father," he added bravely.
The French planes were too much for the Germans, and soon drove them back beyond the Hun lines, though perhaps not before the enemy aviators had made the observations desired.
"Well, they didn't see much," remarked Jack. "As far as any real damage was done to Paris it doesn't count, from a military standpoint."
"No, you're right," agreed Tom. "Of course they have killed some noncombatants, but that seems to be the Boche's principal form of amusement. As for getting any nearer to the capture of Paris this way, he might as well throw beans at the pyramids. It's probably done for the moral, or immoral, effect."
And this seemed to be the view taken of it by the Paris and London papers. The method of bombardment, however, remained a mystery, and a baffling one. This was a point the military authorities wished to clear up. To that end it was much to be desired that fragments of the shell should be found. And to find them, if possible, a careful search was made, not only in the ruins of the Rue Lafayette, but at the other two places where the explosions had occurred.
In no place, however, was a large enough fragment found to justify any conclusive theories, and the Parisians were forced to wait for another bombardment—rather a grim and tense waiting it was, too.
But the careful search of the Rue Lafayette ruins proved one thing. The body of Tom's father was not among them, though this did not make it certain that he was alive. He may have been totally destroyed, and this thought kept Tom from being able to free his mind of anxiety. He dared not cable any news home, and all he could do was to keep on hoping. These were anxious days for him and Jack.
Their leave of absence had been for a week only, but under the circumstances, and as it was exceptionally quiet on their sector, they were allowed to remain longer. Tom wanted to make a more thorough search for his father, and the police and military authorities helped him. But Mr. Raymond seemed to have completely disappeared. There was no trace of him since the agent for the Rue Lafayette buildings had seen him leave his room just prior to the falling of the shell.
Jack inquired about the man he suspected of being a German spy. The secret service men had him under observation, they reported, but, as yet, he had not given them any cause to arrest him. They were waiting and watching.
Meanwhile active preparations were under way, not only to discover the source of the bombardment of Paris, but to counteract it. Extra anti-aircraft guns, of powerful calibre, were erected in many places about the city, and more airmen were summoned to the defense.
As yet there had been no resumption of the bombardment, and there were hopes that the German machine, whatever it was, had burst or been put out of commission. But on the second day of the second week of the boys' stay in Paris, once more there was the alarm and the warning-from the soldiers and police, and again came that explosion.
The bombardment of Paris was being renewed!
Two things were at once apparent to Tom and Jack as they hurried out of theirpension. One was that the people of Paris were not seeking shelter after the warnings as quickly as they had done at first, and the other was that there was evident curiosity on all sides to see just what damage would be done, and from which direction it would come. With an almost reckless disregard for their safety, if not for their lives, the Parisians fairly flocked out of doors to see the results of the Huns' bombardment. It was in vain that the police and military urged them to seek safety in cellars or the places provided.
This time only one shell fell near enough to Tom and Jack to make the explosion heard, and that was so faint as to indicate that it was some distance off. What damage had been done could only be guessed at.
"But we'll find out where it is, and go take a look," said Jack.
"Maybe it'll hit right around here if we stay," suggested his chum.
"Well, I'm not taking that chance," Jack went on. "Let's find out where it landed this time."
This they could do through their acquaintance with the military authority of the district where they were then staying. A telephonic report was at once received, giving the quarter where the shell had landed. It had fallen in one of the public squares, and though a big hole had been torn in the ground and pavement, and several persons killed and wounded, no material damage had been done. As for any military effect of the shell, it was nil.
The firing was done in the early evening hours, and Tom and Jack learned that, almost to the second, the shots were fifteen minutes apart.
There was one theory that an underground passage had been made in some manner to within a comparatively few miles of Paris, and from that point an immense mortar sent up the shells in a long trajectory.
Another theory was that traitors had let the Germans through the French lines at a certain place, so they could get near enough to Paris to bombard it.
And of course the gigantic airship theory had its adherents.
But, for a time at least, no one would admit the possibility of a gun with range sufficient to shoot into Paris from the nearest German lines. The range, sixty-odd miles, seemed too great for practical belief, however nicely it might work out in theory.
"And you must remember that the gun, if gun it is, couldn't be in the very first German line," said Tom, who had studied ordnance. "It must be at least ten miles back, to allow for sufficient protection from the French guns. That would make it shoot about seventy-two miles, and I don't believe any gun on earth could do it!"
"Neither do I," added Jack. "We've got to dope out something else. But this isn't finding your father, Tom."
"I know it, and I don't mind admitting I'm clean discouraged about him, Jack. If he's alive why doesn't he send me some word? He must know where I am, and, even if he doesn't know I'm in Paris, they would forward any message he might send to our aeroplane headquarters."
"That's right. But what are you going to do about it?"
"I hardly know. He may still be in Paris, but it's such a big city that it's hard to find him. Then, too, I'm thinking of something else."
"What's that, Tom?"
"Well, dad may not want us to know where he is."
"Why in the world would he want such a thing as that?"
"Well, he might be followed, or bothered by spies. Perhaps he has come over to do some special work for the French or English army people. Maybe a spy was after him just before the big German gun wrecked his Rue Lafayette house. He may have considered this a good chance to play dead, and that's why he doesn't send some word to me."
"That's a good theory. But it isn't very comforting."
"No, but there isn't much comfort in war times. We've got to make the best of it."
"I guess you're right, Tom. Now do you want to go look at the latest work of the Hun?"
"Might as well. The bombardment seems over for the night."
"I wonder why it is they don't fire after dark."
"Probably afraid of giving the location of their cannon away by the flashes. They'd be seen at night; but during the day, if they used smokeless powder, or a smoke screen in case they can't get smokeless powder for such a big gun, it would be hard to locate the place where the shots come from. So we're comparatively safe after dark, it seems."
Later this was not to prove to be the case, but it was when Tom spoke.
The boys went to the section of the city in which the last shells had fallen. While comparatively little damage had been done, a number of persons had been killed and injured, children among them. Some fragments of the shells were picked up, but not enough to make certain any particular theory in regard to the gun.
"But if it's a gun, where could it be placed?" queried Tom of an officer. "The Germans haven't broken through, have they?"
The French officer shook his head.
"No. And please God they will never get through," he said. "But there is a gun somewhere, I am sure of that."
"Do you mean to say within ten or fifteen miles of Paris?" Jack wanted to know.
"I can not be sure. It is true there may have been traitors. We have them to contend with as well as spies. But our line is intact, and at no point along it, near enough to it to fire into Paris from an ordinary gun, can the Germans be found."
"Then it must be an extraordinary gun," suggested Jack.
"It may well be—perhaps it is. Yet, as I said, there may have been traitors. There may be a gun concealed somewhere closer to Paris than we dream. But we shall find it, messieurs! Who knows? Perhaps you may be the very ones yourselves to locate it, for we are depending on you soldiers of the air."
And it was not long before this talk came back to Tom and Jack with impressive recollection.
And meanwhile the bombardment of Paris went on, usually during the late afternoon or early morning hours—never at night, as yet.
Yet with all the frightfulness of which the unscrupulous Huns were capable, it was impossible to dampen for long the spirits of the French. Soon they grew almost to disregard the falling shells from the hidden German gun. Of course there were buildings destroyed, and lives were lost, while many were frightfully maimed. But if Germany depended on this, as she seemed to, to strike terror to the hearts of the brave Frenchmen the while a great offensive was going on along the western front, it failed. For the people of Paris did not allow themselves to be disheartened, any more than the people of London did when the Zeppelins raided them.
Indeed one Paris paper even managed to extract some humor out of the grim situation. For one day, following the bombardment, a journal appeared with "scare" headlines, telling about eleven "lives" being lost. But when one read the account it was discovered that the lives were those of chickens.
And this actually happened. A shell fell on the outlying section and blew up a henhouse, killing nearly a dozen fowls and blowing a big hole in the ground.
There were other occasions, too, when the seemingly superhuman bombardment was not worth the proverbial candle. For the shells fell in sections where no damage was done, and where no lives paid the toll. Once a shell went through a house, passing close to an aged woman, but not hurting her, to explode harmlessly in a field near by.
And it was with such accounts as these that the Paris papers kept up the spirits of the inhabitants. Meanwhile the Germans kept firing away at quarter-hour intervals, when the gun was in action.
"I wonder if there is any chance of us getting in at the game?" questioned Jack of Tom one night.
"I shouldn't be surprised. As that officer said, they'll have to depend on the aircraft to locate the gun, I'm thinking."
"And you think we have a chance?"
"I don't see why not," replied Tom. "We've been off duty long enough. I'd like to get back behind the propeller again, and with a drum or two of bullets to use in case we sight a Hun plane. Let's go and send word to our captain that we've had enough of leave, and want to go out again."
"All right. But what about your father?"
"Well, I don't know what to say," answered Tom. "I'm about convinced that he wasn't killed, or even hurt, in any of the bombardments of Paris. But where he is I don't know. I guess, as a matter of duty to France, I'll have to let my private affairs go and—"
At that instant there sounded an explosion the character of which the two boys well knew by this time.
"The big gun again!" cried Jack.
"Yes, and they're firing after dark!" added Tom. "This may be just the chance the airmen have been waiting for—to locate the piece by the flashes. Come on out and see what's doing!"
Together they rushed from their room.
Much the same sort of scene was going on in the streets of Paris as Tom and Jack had witnessed when first the populace realized that they were under fire from a mysterious German cannon. There was the initial alarm—the warnings sounded by the police and soldiers, warnings which were different from those indicating a Zeppelin or aircraft raid, and then the hurry for cover.
But it was noticeable that not so many of the people rushed for a secure hiding place as had done so at first.
"They're not so afraid of the big gun as they were," observed Jack, as he hurried along with his chum.
"No. Though it's just as well to be a bit cautious, I think. The people of Paris are beginning to lose fear because they see that the German shells don't do as much damage as might be expected."
"You're right there, Tom," said Jack. "The shells are rather small, to judge by the damage they do. I wonder why that is?"
"Probably their gun, or guns, can't fire any larger ones such a long distance, or else their airships can't carry 'em up above the clouds to drop on the city."
"Then you still hold to the airship theory?"
"Well, Jack, I haven't altogether given it up. I'm open to conviction, as it were. Of course I know, in theory, a gun can be made that will shoot a hundred miles, if necessary, but the cost of it, the cost of the charge and the work of loading it, as well as the enormous task of making a carriage or an emplacement to withstand the terrific recoil, makes such a gun a military white elephant. In other words it isn't worth the trouble it would take—the amount of damage inflicted on the enemy wouldn't make it worth while."
"I guess you're right, Tom. And yet such a gun would make a big scare."
"Yes, and that's what the Germans are depending on, more than anything else."
"But still don't you think the French will have to do something toward silencing the gun?"
"Indeed I do! And I haven't a doubt but the French command is working night and day to devise some plan whereby the gun can be silenced."
"There go the aviators now, out to try to find the big cannon," observed Jack, as he gazed aloft.
Soaring over Paris, having hastened to take the air when the signal was given, were a number of planes, their red, white and blue lights showing dimly against the black sky. They were off to try to place the big gun, if such it was, or discover whether or not some Hun plane was hovering over the city, dropping the bombs.
As Jack and Tom hastened on, in the wake of the crowd, which was hurrying toward the place where the latest shells had fallen, again came a distant explosion, showing that the gun had been fired again.
"Fifteen-minute interval," announced Tom, looking at his watch. "They're keeping strictly to schedule."
"Night firing is new for the big gun," said Jack. "I do hope they'll be able to locate the cannon by the flashes."
"It isn't going to be easy," asserted Tom.
"Why not?"
"Because you can make up your mind if the Germans were afraid to fire the piece at night at first for fear of being discovered, and if now they are firing after dark, they have some means of camouflaging the flash. In other words they have it hidden in some way."
"Well, I suppose you're right. But say, Tom, old man! what wouldn't I give to be able to be up in the air with those boys now?" and Jack motioned to the scouts who were flitting around in the dark clouds, seeking for that which menaced the chief city of the French nation.
"I'd like to be there myself," said Tom. "And if this keeps up much longer I'm going to ask permission for us to go up and see what we can do."
"Think they'll let us?"
"Well, they can't any more than turn us down. And we've got to get at it in a hurry, too, or we'll have to report back at our regular station. We aren't doing anything here, except sit around."
"No, we must get busy, that's a fact," said Jack. "It's about time we downed some Hun scout, or broke up one of their 'circus' attacks. I've almost forgotten how a joy stick feels."
A "joy stick" is a contrivance on an aeroplane by the manipulation of which the plane is held on a level keel. If the joy stick control is released, either by accident (say when the pilot is wounded in a fight), or purposely, the plane at once begins to climb, caking its passenger out of danger.
Once the joy stick is released it gradually comes back toward the pilot. The machine climbs until the angle formed is too great for it to continue, or for the motor to pull it. Then it may stop for an instant when the motor, being heavier, pulls the plane over and there begins the terrible "nose spinning dive," from which there is no escape unless the pilot gets control of his machine again, or manages to reach the joy stick.
"Well, we'll have to get in the game again soon," said Tom. "But what do you say to taking a taxi? This explosion is farther than I thought."
Jack agreed, and they were soon at the place where the last German shell had fallen—that is as near as the police would permit.
A house had been struck, and several persons, two of them children, killed. But, as before, the military damage done was nothing. The Germans might be spreading their gospel of fear, but they were not advancing their army that way.
As Tom and Jack stood near the place where a hole had been blown through the house, another explosion, farther off, was heard, and there was a momentary flare in the sky that told of the arrival of another shell.
For a few seconds there was something like a panic, and then a voice struck up the "Marseillaise," and the crowd joined in. It was their defiance to the savage Hun.
A few shots were fired by the Germans, but none of them did much damage, and then, as though operating on a schedule which must not, under any circumstances, be changed, the firing ceased, and the crowds once more filled the streets, for it was yet early in the night.
The next morning the boys went to report, as they did each day, expecting that they might be called back to duty. They also found, after being told that their leave was still in effect, that some of the aviators who had gone up the night before, to try to locate the German gun, were on hand.
"Now we can ask them what they saw," suggested Jack.
"That's what we will," assented Tom.
But the airmen had nothing to report. They had ascended high in search of a hostile craft carrying a big gun, but had seen none.
They had journeyed far over the German lines, hoping to discover the emplacement of the gun, if a long range cannon was being used. But they saw nothing.
"Not even flashes of fire?" asked Tom.
"Oh, yes, we saw those," an aviator said. "But there were so many of them, and in so many and such widely scattered places, that we could not tell which one to bomb. We did manage to hit some, though with what effect we could not tell."
"Then the German gun is still a mystery," observed Tom.
"It is. But we shall discover it soon. We will never rest until we do!"
So more and new and different theories continued to be put forth regarding the big cannon, if such it was. Ordnance experts wrote articles, alike in London, Paris, and New York, explaining that it was possible for a cannon to be within the German lines and still send a shell into the French capital. But few believed that it was feasible. The general opinion was that the gun was of comparative short range, and was hidden much nearer Paris than the sixty or seventy-odd miles away, beyond which stretched the German line of trenches.
Meanwhile Tom, though making careful inquiries, had learned nothing of his father. He did not feel it would be wise to cable back home, and ask what the news was there.
"It might spoil dad's plans if I did that," said Tom to his chum, "and it would worry the folks in Bridgeton to know that I haven't yet seen him in France. No, I'll just have to wait."
And wait Tom did, though there is no harder task in all the world.
It was one morning, after a night bombardment on the part of the Germans, that Jack, who had been out for a morning paper, came rushing into the room where Tom was just awakening.
"Great news, old man! Great!" cried Jack, waving the paper about his head.
"You mean about a victory?" asked Tom.
"No, not exactly, though it may lead to that. And it isn't any news about your father, I'm sorry to say. It's about the German gun. A 'dud' fell last night."
"A 'dud'?" repeated Tom, hardly sensing what Jack said.
"Yes, you know! A shell that didn't explode. Now they have a whole one to examine, and they can find out what sort of gun shot it. This paper tells all about it. Come on! Let's go for a look at the 'dud'!"
Tom, dressing hastily, read the account in the Paris paper of the fall, in an outlying section of the city, of one of the German shells that failed to explode. It was being examined by the military authorities, it was stated, with a view to finding out what sort of gun fired it, so that measures might be taken to blow up the piece or render it useless to the enemy.
"That sounds good to me," said Tom, as they made a hasty breakfast. "This is getting down to a scientific basis. An unexploded shell ought to give 'em a line on the kind of gun that fired it."
"The only trouble," said Jack, "is that the shell may go off when they are examining it."
"Oh, trust the French ordnance experts not to let a thing like that happen," said Tom. "Now let's go to it."
It was fortunate that Tom and Jack wore the uniforms that had so endeared them to France, or they might have had difficulty in gaining admittance to the bureau where the unexploded shell was under process of investigation. But when they first applied, their request was referred to a grizzled veteran who smiled kindly at them, patted them on the shoulders, called them the saviors of France, and ushered them into the ordnance department, where special deputies were in conference.
"Yes, we have one of the Boche shells," said an officer, who spoke English fluently, for which Tom and Jack were glad. They could speak and understand French, but in a case like this, where they wanted a detailed and scientific explanation, their own tongue would better serve them.
"And can you tell from what sort of gun it comes?" asked Tom.
"It was fired from a monster cannon," was the answer. "That is a cannon not so much a monster in bore, as in length and in its power to impel a missile nearly eighty miles."
"Can it be done?" asked Jack.
"It has been done!" exclaimed Major de Trouville, the officer who was detailed to talk to the boys "It has been done. That is the gun that has been bombarding Paris."
"But, from a military standpoint," began Tom, "is it—"
"It is utterly useless," was the quick answer. "Come, I will show you the shell."
He led them to an apartment set aside for the testing of explosives and working out ordnance problems, and there on a table, around which sat many prominent French officials, was the German shell—the "dud," as Jack had called it.
"The charge has been drawn," explained Major de Trouville, "so there is no danger. And we have determined that the manner in which shots reach Paris from a distance of from seventy to eighty miles is by the use of a sub-calibre missile."
"A sub-calibre?" murmured Tom.
"Yes. You know, in general, that the more powder you use, and the larger the surface of the missile which receives it, the greater distance it can be thrown, providing your angle of elevation is proper."
The boys understood this much, in theory at least.
"Well," went on the major, "while that is true, there is a limit to it. That is to say you could go on using powder up to hundreds of pounds in your cannon, but when you get to a certain point you have to so increase the length of the gun, and the size of the breech to make it withstand the terrific pressure of gases, that it is impracticable to go any further. So, also, in the case of the shell. If you make it too large, so as to get a big surface area for the gases of the burning powder to act upon, you get your shell too heavy to handle.
"Now of course the lighter a missile is, the farther it will go, in comparison to a heavy one with the same force behind it. But you can not get lightness and sufficient resistance to pressure without size, and here is where the sub-calibre comes in."
"In other words the Germans have been firing a shell within a shell," broke in another officer.
"Exactly," said Major de Trouville. "The Germans have evolved a big gun, that is big as regards length, to enable the missile they fire from it to gain enough impulse from the powder. But the missile would be too large to travel all the way to Paris. So they use two. The inner one is the one that really gets here and explodes."
"What becomes of the outer?" asked Jack.
"It is a sort of container, or collar, and falls off soon after the shell leaves the big gun. If you will imagine a sort of bomb shell being enclosed in an iron case, the whole being put in a gun and fired, you will better get the idea. The outer case is made in two or more pieces, and soon after it is shot out it falls away, leaving the smaller missile to travel on. But here is where the cunning of the invention comes in. The smaller missile has all the impetus given the larger one, but without its weight. In consequence it can travel through eighty miles of atmosphere, finally reaching Paris, where it explodes."
"Wonderful!" exclaimed Jack.
"And yet it is merely the adaptation of an old theory," went on the major. "We have known of the sub-calibre theory for years, but it is not practicable. So we did not try it. The cost is too great for the amount of military damage done. And this shell, as you will see, is composed of two parts, each with a separate explosive chamber, each containing, as we discovered, a different sort of explosive. In this way if one did not go off, the other would, and so set off the one that failed. It is very clever, but we shall be more clever."
"That's right!" chimed in a chorus of fellow officers.
"We'll find the gun and destroy it—or all of them if they have more than one, as they probably have," went on the major.
He showed the boys where the shell had chambers for the time fuses to work, much as in a shrapnel shell, which can be set to go off so many minutes or so many seconds after it reaches its objective point.
"And so the great question is settled by the failure of this shell to explode," went on the major. "As soon as we saw it, and noted the absence of the rifling groove marks, we knew it must have been a sub-calibre matter. The rest was easy to figure out.
"Some of us thought there might be a big airship, stationed high above the clouds, dropping bombs. Others inclined to the theory of a double shell; that is, after one had been fired from the cannon it would travel, say, half way and then explode a charge which would impel another shell toward Paris. A sort of cannon within a cannon, so to speak. But this is not so. Nor did the theory of a shell with a sort of propeller device, like that of a torpedo, prove to be right. It is much simpler—just sub-calibre work."
"And what is going to be done about it?" asked Tom. "I mean how can the monster cannon be silenced?"
"Ah, that is a matter we are taking up now," was the answer of Major de Trouville. "I fancy we shall have to call on you boys for a solution of that problem."
"On us?" exclaimed Jack.
"Well, I mean on the aircraft service. It will be their task to search out this great German cannon for us, to enable our gunners to destroy it. Or it may be that it will have to be bombed from an aeroplane."
"That's the task I'd like all right!" cried Tom, with shining eyes.
"Same here!" echoed Jack. "Do you suppose we'll get a chance?" he asked eagerly.
"You may," was the reply. "It may take all the resources of our airmen to destroy this terror of the Germans. But it will be done, never fear!"
"Vive la France!" cried his companions, and there was a cheer in which Tom and Jack joined.
And so a part of the secret was discovered. It was a monster cannon that was devastating Paris. A great gun, the construction of which could only be guessed at. But it must be destroyed! That was certain!
Tom and Jack spent some little time looking at the strange German shell. It was of peculiar construction, arranged so that the two explosive charges would detonate together or separately, according as the mechanism was set.
But in this case it had failed to work, and the shell, falling in a bed of soft sand, near some new buildings which were going up, had not been fired by concussion, as might have happened.
"And it was just French luck that it didn't go off," observed Jack.
"That's right," agreed Tom. "If they hadn't had this whole shell to examine they wouldn't know about the big gun."
So all the theories, fantastic enough some of them, about great airships hovering over the beautiful city, and dropping bombs from a great height, were practically disproved.
"Well, now that you have decided it is a big German gun, the next question is, where is it and what are you going to do about it?" observed Tom, for he and Jack had been made so much of by the French officers that they felt quite at home, so to speak.
"Ah, messieurs, thatisthe question," declared Major de Trouville. "First to find the gun, and then to destroy it. The first we can do with some degree of accuracy."
"How?" asked Tom.
The major went to a large map hanging on the wall of the room. It showed the country around Paris and the various lines as they had been moved to and fro along the Western front, according as the Germans advanced or retreated.
"You will observe," said the major, "that by describing an arc, with Paris as the center of the circle, and a radius of about seventy-five miles, you will include a small sector of the German trenches. Roughly speaking this arc will extend from about Hamegicourt to Condé, both within the German lines, I am sorry to say. Now then, somewhere in this arc, or perhaps back of it, the German gun is placed. Anywhere else where it would be possible for such a monster engine of war to be erected, would bring it too close to our batteries.
"So that gives us the comparative location of the gun," went on the French officer. "But the next question is not so easy to settle—how to get rid of it. As I said, I think we shall have to depend on you airmen."
"Well, we're for the job!" exclaimed Tom.
"I know you are. And it may fall to you, or to your friends. I will talk of that later."
"Have you been able to get any idea of the kind of gun it is, or why it fires at fifteen minute intervals?" asked Jack.
"We have been able to get no really reliable information save that which we deduce by our observations of this shell and from what we know of the location of our own and the German lines," the Major went on. "Up to now our airmen have not been able to penetrate far enough without being attacked, and such few as did get well over toward the Rhine could make out nothing. I have no doubt the gun is well camouflaged."
"And is it true that it doesn't fire at night because the Germans are afraid the flashes will be seen?" asked Tom.
"That may have been the reason at first, but they have fired at night, of late, so they must have some way of concealing the flashes, or perhaps setting off other flashes at the same time so as to confuse our scouts."
"It's going to be some job," murmured Jack.
"You said something," agreed his chum.
They remained talking a little longer, and some of the officers who knew the reason for Tom's visit to Paris, expressed regret that he had no information as yet about his father.
"But take heart," one told him. "He is not dead, or we should have heard of it. Of course he may have fallen into the hands of the Germans, and then we would not know for some time."
"He may have been caught," agreed Tom. "While Tuessig is out of the game on account of his injuries, he may be able to direct Potzfeldt, and that scoundrel would have good reason for trying to get revenge on us."
"Ah, yes, I heard about your rescue of the young lady and her mother," said the major. "It was a brave deed."
"Oh, any one could have done it," said Tom, modestly.
"And have you seen them since they came to Paris?" the major proceeded.
"No, but I wish we could find them!" burst out Jack, and then he blushed at his impetuosity, while Tom murmured something about "Bessie," and Jack promptly told him to hold his tongue.
"Perhaps you may meet them sooner than you expect," went on the French officer.
"Now I wonder what he could have meant by that?" asked Jack, as he and his chum went out, after a final look at the German shell. "Does he know where they are?"
"It wouldn't be surprising, seeing that Mrs. Gleason is probably in Red Cross work, and Bessie may be helping her. We should have looked them up before," went on Tom. "But what with searching for my father, and the excitement about the bombardment, I really forgot all about them."
Jack did not say whether he had or not, the chances being that he had, more than once, thought of Bessie Gleason.
During the next two days the monster cannon continued to shoot shells at intervals into Paris. Some did considerable damage, as any shell would do in a great city, and many unfortunates were killed. But there was no reign of terror such as, undoubtedly, the Boches hoped to create. Paris remained calm, and there were even jokes made about the cannon. It was called a "Bertha" and other names, the former referring to Bertha Krupp, one of the owners of the great German ordnance works.
Word was given out that the French gunners on the front were trying to reach the big gun with their missiles. But as they were firing blindly it could not be said what havoc had been wrought.
"But, sooner or later, we'll get the range, and get within striking distance," said one of the French officers. "Then we'll show them a trick or two."
"Have the aviators done anything toward trying to find the gun?" asked Tom. "I mean anything more."
"We are perfecting our plans for the flying corps," was the answer. "Perhaps you shall know more in a few days."
"Well, I hope we'll be here when the fun begins," said Tom, grimly. "We've got another extension of leave, and I'm going to ask the police now, to co-operate with the military in seeking my father."
"I think that will be a wise plan. We will give you all the help we can."
But the quest for Mr. Raymond seemed a hopeless one, and as no confirmation could be had of his death or injury, the idea gradually became fixed in the minds of Tom and Jack that he had been made a German prisoner.
"If that is so, and I can get any trace of him, I'll go over the Rhine to get him back," snapped Tom.
"And I'll go with you!" declared his chum.
It was a few days after they had inspected the German "dud," and the boys were wondering what new developments might take place, the shelling of Paris meanwhile continuing at intervals, that one evening the boys were visited in their lodgings by Major de Trouville.
"Is there any news?" eagerly asked Tom, for he guessed that the French officer would not be paying a merely social call. Those were the strenuous days when such things had passed.
"Well, yes, news of a sort," was the answer. "But what I came to find out was whether you were so taken with these lodgings that you could not be induced to move."
"To move!" exclaimed Jack.
"Yes. Have you found anything unhealthful here?"
"Why, no," replied Tom, wonderingly. "We like it here. The landlord couldn't be nicer, and we're in a good location."
"Nevertheless, I fear I shall have to ask you to change your quarters," went on the major, and by the quizzical smile on his face the boys guessed that there was something in the wind.
"Let me ask you another question," went on the French officer. "Have you been annoyed since you have been here?"
"Annoyed? How?" inquired Tom.
"By unwelcome visitors, or by strangers."
The boys thought for a moment.
"There's one chap who lives in the same building here, whom we've seen on our staircase several times," said Jack, slowly. "Once I saw him pause at our door with a key, as though he were going to enter, but he heard me coming, and, muttering that he had taken too much wine and was a bit hazy in his memory, he went on upstairs."
"I thought as much," the major said. "Was the man you speak of familiar to you?"
"No, I can't say that he was," replied Jack, and Tom nodded his acquiescence. "I never saw him before."
"Oh, yes you have," and the major smiled.
"I have? Where?"
"On the train, coming into Paris."
"You mean the German spy?" cried Jack.
"The same," answered the Frenchman. "That's just what he is, and he is spying on you. Now, in view of what is going to happen, we don't want that to go on. So I have come to ask you to change your lodgings, and I think I can take you to one that will be most agreeable to you both."
"But what does all this mean?" asked Tom. "Is there——"
"There is 'something doing' as you say so picturesquely in the United States," interrupted the major. "I have come to tell you that you are to undertake a most perilous mission!"
Tom Raymond and Jack Parmly looked first at one another and then at the major. He had been smiling at their wonderment, but he was now serious, and regarded them gravely.
"Do you mean we have to do something to help catch this spy?" asked Tom.
"I'd like a hand in that!" exclaimed Jack. "I saw him first—he's my meat!"
"Well, get him if you can, boys," said the Frenchman. "But I did not come here to talk so much about him as about yourselves. The spy is a danger and a menace, but we know him and if he goes too far we can put out our hands and drag him back.
"No, what I referred to is more dangerous than merely trying to catch a spy at his sneaking work. I will tell you." The major suddenly left his seat near the window of the boy's room, and quickly opened the door leading to the hall. The passage was empty.
"I rather thought there might be an eavesdropper," the major explained. "I was followed here, though I don't believe the spies know my mission. However, it is best to be careful. With your permission I'll pull down the shade. There may be spies stationed across the street who, with powerful glasses, might look through the window and gather something of what we say by reading our lips. It has been done."
"The Germans don't leave much untried," commented Tom. "But what is it you want us to do, if it isn't trying to trail the spy?"
The major motioned them to draw closer to him, and then, leaving the door into the hall open, so that he could note the approach of any one, he whispered:
"You are to be two members of a picked company of air scouts who are to go out, discover the big German gun, and destroy it!"
"Whew!" whistled Tom, after a moment of thought during which he and Jack exchanged quick glances.
"Well?" asked the officer. "How does that strike you? I believe that is another of your captivating terms?"
"It's all to the good!" exclaimed Jack. "What say, Tom? We'll take that on, won't we?"
"Well, I should say!" was the enthusiastic rejoinder. "When do we start to—"
"Hush!" cautioned the major. "Not so loud. Though we have taken every precaution, there may be spies unseen by us. We had better talk no more about it here."
"Then let's go to our new lodgings, if we are to move," suggested Tom. "Will it be safe to talk there?"
"I think so," the major said. "At least you will be among friends. Not that your landlord here is not a true Frenchman; but he can not control the actions of those to whom he lets lodgings. You will be better where you are going. Then you accept the mission?" he asked in another whisper.
"Sure thing!" answered Tom, while Jack nodded his assent. "The sooner the quicker!"
"I do not quite get that," the major confessed with a smile. "But I think I gather your meaning. Now if you will proceed to this address," and he handed Tom a small slip of paper, "you will find a comfortable lodging, and you will be among friends."
"How soon can we start on—on this mission?" asked Tom.
"It will be better not to refer to it directly," the officer said. "Talk as little about it as you can. But you shall go as soon as the arrangements can be made. You will be notified."
"And what about seeing our friends—Mrs. Gleason?" asked Jack.
"Are you sure itsMrs.. Gleason you want to see?" inquired Tom.
"Oh, cut it out!" advised Jack with a blush.
"You may see them soon now," the major told him with a smile. "And I hope you'll soon have good news of your father," he added to Tom.
"I hope so, too. The suspense is telling on me."
"I should think it would. Now don't leave this bit of paper about with the address of your new lodgings on. Better commit it to memory, and then destroy the sheet. We want, if possible, to prevent the spy from knowing where you have gone. I will call a taxicab for you. You can be packed soon, I suppose?" he questioned.
"Within a half hour," answered Jack. "But say, won't that spy be on the watch, and won't he learn from the taxicab driver where we have gone?"
"Not fromthistaxicab driver," was the smiling answer. "He is one of our best secret service men. But treat him as you would an ordinary chauffeur. You may even give him a tip, and he will not be offended," and once more the major smiled.
Tom and Jack, having made sure they remembered the address given them, destroyed the paper, and then proceeded to get ready to move. Meanwhile Major de Trouville took his departure, promising to keep in communication with the Air Service boys.
Punctual to the half hour a taxicab appeared at the door. The boys obeyed the instructions they had received, and looked out to make sure the spy was not on hand. If he was, he was well concealed, for they did not see him.
"Though I suppose he's somewhere around," said Jack.
"Well, maybe we can fool him," suggested Tom. "We're going quite on the other side of Paris."
They made sure that, as far as could be told by observation, there was no one resembling the spy around the place or in the street in front, and then got into the cab with their baggage. The chauffeur seemed not to know them, but Tom thought there was just the slightest wink of one eye, as though to indicate that the game was going well.
Their cab was driven out along the Boulevard Ragenta, past the Gare du Nord, and across the Boulevard de Rochechquart to a small street running off the Rue Ramey, and there the cab stopped in front of a small but neat-looking house.
"Quiet enough neighborhood," remarked Jack, as they got down, and Tom tipped the cabman for the benefit of any spies who might be looking.
"Yes, I guess we can get some sleep here, if the big gun doesn't keep us awake," agreed Tom.
On the way they had passed several places where the havoc of the "Bertha" was noticeable.
Tom and Jack seemed to be expected, for the porter, who came down to get their bags, did not seem at all surprised to see them. He bade them follow him, and a little later, the cab having chugged off, the boys were settled in a pleasant room, a smiling landlady coming in to see if they wanted anything, and to tell them they could have meals with her at certain hours, or they might dine out as they pleased.
"Your friends will be here shortly," she added.
"Our friends?" questioned Tom.
"Yes," with a nod and a smile. "I was told to say they would be here shortly after you arrived."
"Oh, I guess she means the major and some of the officers will come to see how we are situated, and to tell us more about—the big stunt," said Tom in English to his chum, assuming that "big stunt" would sufficiently disguise to any listening spies, if such there were, the real object that lay before them.
"I suppose that's who she means," agreed Jack, as the landlady, who gave her name as Madame Reboux, withdrew.
The boys were busy unpacking their few belongings, for they had not brought much to Paris, not intending to stay long, when they heard voices in the hall outside their room. And at the tones of a certain voice Tom and Jack started and looked at one another.
"Listen!" exclaimed Tom.
"If I wasn't afraid you'd say I was dreaming, I'd say I knew that voice!" murmured Jack.
"I'd say the same," added Tom.
"Who would you say it was?" his chum challenged.
"Well, for a starter—"
He paused, for the voice sounded more plainly now, and it said:
"Yes, this is the right place, Mother. Oh, do you think the boys are here yet?"
"It surely will be a pleasure to meet them again," said another voice, evidently that of a woman, the other having been a girl's.
"I hope they won't have forgotten us," the girl went on, and at that Jack could no longer keep quiet. He rushed to the door, opened it, and cried:
"Bessie! Is that you?"
"Oh, it's Jack! Mother, here's Jack!" cried the girl, and she and her mother were soon shaking hands with Tom and Jack.
"So, you two were the friends we were soon to see!" exclaimed Tom, as he placed chairs for Mrs. Gleason and her daughter. Or, to be exact, Tom placed a chair for the mother, while Jack got one for Bessie.
"Yes, we were told you would be here," said Bessie's mother. "We did not know you were in Paris until we received word that it would be better for us to change our lodging and come here."
"The same word we received," said Jack. "Say, it's working out mighty queer, isn't it, Tom?"
"Yes, but very satisfactorily, I should say. Things couldn't be nicer. How have you been?" he asked, for he had not seen the girl nor her mother since the sensational rescue from the perfidious Carl Potzfeldt.
"Very well indeed," answered Mrs. Gleason. "Both Bessie and I have been doing Red Cross work. But isn't that great German gun terrible? Oh, how it has killed and maimed the poor women and children! The Huns are fiends!"
"I quite agree with you," said Tom, Jack meanwhile talking to Bessie. "But it isn't doing them the military good they thought it would, and, if all goes well, it may not very long do them any service at all."
"You mean—" began Mrs. Gleason.
But just then Bessie, who had arisen to go to the window to view the street, turned back with a start, and grasped Jack's hand.
"Look! Look!" she whispered, and through the curtains she pointed to a man on the opposite side of the way.
"Do you know him?" asked Jack.
"Know him? Yes, to my sorrow."
"Who is it?" asked Tom.
"The spy!" exclaimed Jack. "The man we saw in the train, and the same fellow who tried to get into our lodgings. In spite of our precautions he has found out where we are."
"I'm not so sure of that," said Tom. "He may not be here for any particular purpose. But do you know him too, Bessie?"
"Yes," the girl answered. "He was in the château where mother and I were held prisoners by Potzfeldt. He is a tool in the pay of that spy, and a spy himself!"
"Then we ought to do something!" exclaimed Jack, and he started to rush from the room.