"Hold on! Wait a minute!" exclaimed Tom, as he caught hold of his chum. "Where are you going?"
"Out to give warning to a policeman or to some army officer about that spy!" exclaimed Jack. "We know him to be such, and now, with Bessie's word that he was with Potzfeldt, it's enough to cause his arrest."
"Yes, maybe it is," agreed Tom, who was a bit more cautious than his impetuous chum. "But if we do that we may spoil the plans of Major de Trouville. Better let matters take their course, Jack. That spy may not know we are here, and again, he may. But if he doesn't, rushing out now would be sure to give the secret away. As it is, there is a chance we may keep it."
Jack, caught midway in his impetuous rush from the room, stood reflectively. What Tom had said to him appeared to make an impression. Then Bessie added her words of advice.
"Yes, Jack," she said, "I think it would be rather rash to go out now and confront that man, or start a chase after him. I know I'm not as experienced as you two famous birdmen," she went on with a smile, "but I've been through some terrible experiences, as almost every girl has in this war zone, and I can do more thinking than I used to. Don't you think it would be wise to wait, Mother?"
"Yes, Bessie," answered Mrs. Gleason, "I do. Our good friends in the military service who told us to come here, must have had some object. Perhaps it was connected with this same man who was so unkind to us in the château, and who was certainly a tool of that man I trusted once, but never will again—Carl Potzfeldt!" and she shuddered as she thought of what she had gone through.
"Let him go," she said to Jack. "Perhaps it is just a coincidence that he is passing just as we arrive. Our departure from our last lodgings was made secretly."
"So was ours," said Tom. "And yet I don't see how that spy found us so soon."
"It is that which makes me think it is accidental," observed Mrs. Gleason. "It would be very unwise now to go out, I think."
"All right, then I'll stay in," said Jack with a smile. "Especially as I have such good company. Tell me," he went on, "are you and your mother going to board here?" he asked Bessie.
"Yes," answered Mrs. Gleason. "And though we were told we would meet friends here we could not guess it would be you brave boys."
"Spare my blushes!" laughed Tom.
"Same here," added Jack.
"But what brings you to Paris?" asked Bessie. "I thought you boys were engaging in combats above the clouds."
"We have been fighting, though not during the last two weeks," said Tom. "I had word that my father had come over here, but he never communicated with us, and we came to Paris to look him up. So far we haven't succeeded in finding him," and he gave the details of the visit of himself and his chum to the capital, telling of their first experience during the firing of the big gun.
Bessie and Jack, who seemed to have much to say to one another, peered from behind the curtains out of the window now and then, and Jack at last reported that the spy had passed on, after stopping, apparently, to purchase some fruit at a stand on the street.
"I don't believe he knew we were here," said Bessie.
"Well, it won't do to take any chances," observed Tom. "However, we were not told to remain under cover, so I suppose we can go out when we like."
"Better wait until we get some word from the major," suggested Jack, who was getting some of his chum's caution.
All decided this was best, and the boys spent the rest of the afternoon in getting their room to rights, Mrs. Gleason and Bessie doing the same in their apartment. Mrs. Gleason had temporarily been relieved from Red Cross work to recuperate, she said, as she had been under a great strain.
Toward evening Major de Trouville, or "Trouville," as he democratically liked to be called, arrived, and when told of the sight in the street of the spy, who turned out to be the same man who was one of the captors of Bessie and her mother, the officer said:
"I am not surprised. In fact I rather looked for that, and it is one reason why I wanted to get you four together so you could see the man at the same time.
"There is now no doubt as to his intentions, and the fact that he was here so soon after you arrived proves that there is a 'leak' somewhere. We suspected as much, and I think I know where it is. It is good information to have. Well, boys, did I surprise you?" he asked, smiling.
"You did, indeed, but it was a pleasant surprise," said Jack.
"But when are we going to be allowed to do something to silence that monster cannon?" asked Tom. "It's pleasant to be here, but we are not forgetting there is work to do."
"Nor would I have you forget," said the major. "A number of persons were killed to-day by fire from the long-range gun. We believe, now, that there are two or three of them, as the shots come at closer intervals. It is imperative that something be done, and so I have brought you orders."
"Good!" cried Jack.
"That sounds like business!" commented Tom.
"In regard to your father," went on the major, addressing Jack's chum, "we will be on the watch for him, or any news of him, and, no matter where you are, unless you are captured by the Germans, you shall be informed as soon as possible."
"Is there any chance of being made prisoners?" asked Jack, and it might be noted that he did not use the word "danger."
"There is always that chance for an airman," replied the major. "But when I add that it may be possible that one or both of you will take a flight over the Rhine, you can judge, with the hold Germany has on French possessions, what the danger is."
"Over the Rhine!" exclaimed Tom. "Why, that's a flight of two or three hundred miles from Paris."
"Yes, but with the new type of Italian plane which you may use, it is not impossible in a single flight," said the major. "However, we will talk of that later. Just now I have come to tell you that you are to rejoin your comrades at the Lafayette Escadrille for a time. There arrangements will be made for the perilous venture I spoke of—the silencing of the big guns that are bombarding Paris. I wish you all success, young gentlemen."
"Thanks," murmured Jack.
"We consider it an honor to be picked for such duty," added Tom. "Are any others going to be in the game?"
"Oh, yes. We shall need a picked corps of the best airmen we have, French and Americans, and it will be no easy matter then. The Germans have probably been planning this for a long time, and they, no doubt, have taken every possible precaution against surprise or failure. But with the help of you brave Americans we shall win!"
"That's right!" chimed in Bessie. "Oh, how I wish I were a man!" and she looked enviously at Jack and Tom.
The major gave Bessie and her mother some instructions in regard to their actions should the spy come back, and then told Tom and Jack to prepare to leave Paris the next night.
"Report to your former camp," he said, "and there you will find further instructions waiting for you."
"Well, then as we have to-night, our last one free, let's go to some entertainment," suggested Tom to Bessie and her mother. "We can have supper afterward—not much of a celebration, for these are war times and it won't do to rejoice too much. But we ought to commemorate this meeting somehow."
"That's right!" agreed Jack.
So they went to a little play and had supper afterward in a quiet restaurant. That is, it was quiet until a sudden explosion a few blocks away announced the arrival of another German shell from the big gun, and then there was excitement enough.
Fortunately, however, the shots did little beyond material damage, no one being killed. At the same time, however, there appeared some German planes over Paris, doubtless to observe the effect of the dropping of the long-distance shells, and naturally the French airmen went up to give them combat.
The great searchlights began to play, picking out the hostile craft, and making them targets for the machine guns of the intrepid Frenchmen, and more than one Boche never got back over his lines again, while several Frenchmen found heroes' graves on the soil they had died to defend.
"Oh, if we were only up there helping," said Tom, as he and his friends watched.
"We shall be there very soon," murmured Jack. "And it can't be any too soon for me."
The tide of battle turned in favor of the French, the Hun planes withdrawing as the fire got too hot for them. And soon after that the long-range gun ceased firing.
It was rather a "pull" for Tom and Jack to say good-bye to Bessie and her mother in Paris, but they knew they had to do their duty. Nor would Mrs. Gleason and her daughter have kept the boys back for the world. They realized that the Air Service boys were helping to make the world safe for democracy, as they themselves were doing in their way.
And so Tom and Jack, their mission to Paris, which was the discovery of Mr. Raymond, having failed, went back to the hangars, there to be welcomed by their comrades in arms.
They arrived one morning, just after some planes from a bombing expedition over the German lines returned.
"What luck?" asked Tom of a pilot with whom he had often flown.
"The best, as regards the damage we did," was the answer. "We blew up several ammunition dumps, and put one railroad center out of business for a time. But Louis didn't come back," and the man turned aside for a moment.
"You mean your brother?" asked Jack, softly.
"Yes."
"Perhaps he is only captured," suggested Tom.
"No, his machine caught fire. They got his petrol tank. It's all up with him and La Garde. But we had our revenge. We sprayed the machine that got them until there was nothing left of it. And I'm going out again to-day in a Nieuport. They'll pay a price for Louis!"
"All ready, Jack?"
"Just a moment, Tom. I want to go over my struts and wires to make sure everything is taut. I don't want any accidents."
"That's right. Got plenty of ammunition drums?"
"All I can carry. I've got some tracer bullets, too."
"That's good. Glad you reminded me of them. I must put in a stock. The last time I went up I wasted a drum before I got my man."
Tracer bullets for aircraft guns, it might be observed, are balls of fire which enable the pilot to see the course his machine gun bullets are taking, so he may correct his fire.
"Well, how about you now?" asked Tom, as he added these useful supplies to his ammunition.
"I guess we're ready to start," replied Jack.
They climbed into their machines, each pilot using a single-seat, swift-flying craft, equipped with a Lewis machine gun. The squadron was going out on patrol duty, and each pilot was to observe what he could behind the German lines, and come back to report—that is if he did not happen, as was too often the case, to be bagged by a German flier. The small, swift machines did not carry the wireless outfit, and no reports could be sent back to headquarters save those the pilot himself came in with.
There was a rattle and a roar as the motors of the ten machines started, and then over the ground they went, "taxi fashion," to get the necessary speed to rise into the air. A moment later all went aloft, and were headed toward the German lines.
Tom and Jack kept as close together as was safe, but it is dangerous for two aeroplanes to approach too closely. If they do, and are not under good control, there may be a suction created that will cause a collision.
"Well, I hope I get one to-day," thought Tom, as he manipulated his "joy stick," so as to send his plane up on a sharp slant. "I want to make good, and then I'll have so much better chance to get after that German gun." And the same thought was in Jack's mind.
The squadron was to remain aloft on a two-hour patrol, that is unless something should occur to make it advisable to remain up longer. The keen eyes of Tom and Jack, as well as those of their companions of the air, were searching for signs of the Hun planes. As yet none were in sight, but it would not be long before they would come out to give battle.
Whatever else may justly be said about the Germans, their airmen are no cowards, and, when conditions are favorable, they seldom decline a chance to combat above the clouds, or lower down. So it could easily be guessed that when Tom, Jack and the others found themselves over the German lines that the Boches would be out in force.
Somewhat off to the left Tom caught sight of a captive German balloon, looming through the mist, and as it is always the desire of a French flier to destroy one of these, thus preventing the observer from sending by wireless news of the Allied front, he started for this enemy. Jack saw his friend's act, and, desiring to aid, turned his machine in the same direction.
But they had not gone far before they observed a number of black specks in the sky over the German lines.
"The Huns are coming," reflected Tom. "Now for some hot work."
And it came to him, to Jack, and the others, almost before they realized it. Tom never got a chance to attack the balloon he hoped to force to descend or to set on fire, for his attention was taken up by two German machines, which, separating from the others, headed straight for him. The lad gave one glance in the direction of Jack, and noted that a single Hun craft was about to engage with his chum.
"It's a regular German circus," thought Tom, referring to the number of hostile craft. "They delight to go out in numbers."
By this time the battle in the air had begun. It was a fight above the clouds, for both the French and the German machines were flying high, and had gone up above the bunches of fleecy vapor that now hid the ground from sight.
Tom headed straight for one of the Hun machines, seeking to get above it, always a point of vantage in an air battle, and as he rushed on he realized that his machine was being hit by bullets from one of the Hun guns.
Each bullet, as it struck, made a loud noise, as it punctured the tightly-drawn linen that covered the wings. But Tom knew that his craft could stand a number of such holes, if only the struts, the supports, and the guy wires were not broken. He had no time, now, to note what Jack or his comrades were doing, for his whole attention was taken up with the two Hun machines engaging him.
One seemed to be more skillful than the other, and to this one Tom gave his attention first. He emptied a stream of bullets full into this flier's craft, noting, after the first few bad shots, which he could tell by the tracers, that he had perfect range.
Guiding his craft with one hand and his feet, Tom worked the Lewis gun with his other hand, and he had emptied a whole drum at the daring Hun before he had the satisfaction of seeing the machine crumple up. Tom's bullets had struck some part that had caused the wings to collapse, and the airman went down to earth, his craft out of control.
But matters were not to go easy with the American. The other German was now in a better position for getting Tom than the latter was for potting him, and Tom felt a stream of bullets flying around him. One chipped his gun, and another grazed his cheek, the close call making his heart stand still for a moment. But he never faltered.
"I've got to get above him," Tom thought fiercely.
He made a risky spiral turn to one side, and began to mount, seeking to get in position to fire to better advantage. It was touch and go for a while, and he felt, rather than heard, his craft receive several bullets.
"If only the gasolene tank isn't hit," thought Tom.
But good fortune in this respect was with him, and he got in a position where he could point his machine (and the gun at the same time, for this is how the guns are aimed in the single aircraft) at the Hun flier. And then Tom sent forth a rain of bullets.
For a moment they seemed to have no effect, and yet Tom knew he had shot straight. Then, even while he felt a sharp pain in one hand, showing that he had been hit, he saw the other machine start down in a spinning nose dive. That meant he was going downward head first, and at the same time spinning around like a top.
This spinning nose dive may be intentional or accidental—that is, with the machine in control, or out of control. The spinning nose dive was discovered by accident, but is now part of the regular flying features, and is often used by aviators to escape from an enemy.
It is almost impossible to hit a plane doing a spinning nose dive, and if an aviator is over his own lines he may be able to come out of it before he reaches the ground, and so be safe. Many German planes have escaped in this way, and often a French airman has thought he has sent his enemy down disabled, when, as a matter of fact, the other has merely adopted this ruse to get away.
"Well, I don't know whether I got him, or whether he got frightened and went down to fool me," thought Tom. "Anyhow they're both out of the way, and I can go after the balloon."
But Tom could not, for two reasons. One was that the wound in his hand was bleeding profusely, and he knew it ought to be attended to before he was incapacitated. Another was that the balloon was being hauled down, and as more French planes were in the air now, making a number superior to the Huns, the latter turned tail and retreated.
It was inadvisable to follow them over their own lines now, and the squadron, or what was left of it, began to retreat. Tom noted the absence of three of the French planes, and among the missing was Jack's.
"I wonder if they got him," Tom mused, his heart becoming like lead. His eyes sought the air about him, but Jack's machine, which carried a little United States flag where it could easily be seen, was not in sight.
It was impossible to get any information up in the air. Tom would have to wait until they got back to the aerodrome. And he put on speed to get there the sooner, in order to end his suspense.
"And the other brave fellows—I wonder what happened to them," mused Tom. In his worry over the fate of Jack and the others he scarcely minded the pain in his hand.
He made a good landing, but being rather weak and faint from loss of blood, he scarcely heeded the congratulations of his comrades, who had received word, by telephone from the front, of the fate of some of the Hun machines. "Where's Jack?" Tom gasped, while a surgeon was putting a bandage on his hand.
"Right here, old scout!" came the unexpected answer, and Jack himself stepped out from amid a throng of airmen. "Why didn't you wait for me?" Jack went on. "I was coming back."
"Coming back? Did you come down safely?" asked Tom, beginning to feel a little better now. Then Tom realized the futility of his question, for was not Jack there in the flesh?
"Of course I came back, old scout," was the answer. "I had hard luck, though, but I'd have gone up again if they'd only waited for me."
"What happened?" asked Tom.
"Oh, just after I potted my man—or at least sent him down out of control—I got a bullet through my gasolene tank. Luckily it didn't set the petrol on fire, but I knew I'd better not take any chances. I tried to plug up the puncture with some chewing gum, but it wouldn't work. Guess the gum they sell now hasn't as much old rubber boot stock in it as it used to have. Anyhow it was leaking like a sieve, and I had to head for our lines."
"Tough luck!" consoled Tom. Jack did not add that he had, as soon as he landed, got into another machine, and was about to go back and join his comrades when they returned, having practically won the battle above the clouds.
Congratulations were extended to the members of the squadron, who accepted their honors modestly enough, as was characteristic of them.
Then, after Tom's wound had been dressed, and he and Jack were talking over the events of the day, there came a communication from the commander of the air division in that sector. It was an order calling on certain men to report at once for special duty. A picked squadron was to be detailed for a hazardous enterprise, it was said.
"And our names are there!" cried Jack. "Tom, old man, we're going!"
"But where is it?" asked another American flier named Boughton. "What's the game?"
Knowing the secret would be safe with him Tom said:
"We're going to pot the big German cannon that's bombarding Paris!"
News of the shelling of Paris by the long-range gun had, of course, been received at the aerodrome, though there had not, as yet, many details come in. Tom and Jack, as the latest arrivals from the big city, were called upon to tell all they knew, and they related their experiences in the raids, and also told about the various theories of the big gun.
"But how are we going to find it?" asked. Boughton. "It's easy enough, of course, for our squadron to go out with a lot of bombs. But where are we going to drop 'em?"
"Oh, we're to go to Paris for further instructions before starting on the quest," said Tom, who had made some inquiries about the orders concerning the picked squadron.
"And they may have discovered its location by this time," added Jack. "We know about where it is—somewhere in the sector between Hamegicourt and Condé. The rest ought to be easy."
"Not so easy as it sounds, my friends," put in a French flier. "I know that region. It is a big one; and the Germans no doubt have their gun well camouflaged. It will not be easy."
"But we'll get it!" asserted Tom.
"Naturally," said the Frenchman, as if that was all there was to it.
Tom's wound was painful, but not dangerous, though it would keep him on the ground for a day or two. Though, as a matter of fact, none of the members of the picked squadron was allowed to go aloft after the orders came detailing them for work in connection with the monster cannon. Their places were taken by others who were sent for, some being new fliers who were burning to make a name for themselves.
Besides Tom and Jack, in the picked squadron there were Boughton, another American, Cerfe and Tierse, two intrepid Frenchmen, and Haught, an Englishman, who insisted, but with little success, that his name be pronounced as though spelled "Hoo."
These six were to be depended on to find and destroy the German cannon—all of them if there were more than one, as was likely. And to this picked squadron other members would be added as need arose. All six were skillful fliers, and brave men of the air, as may easily be guessed. They were to use whatever type of machine they liked best—the single seaters, the great bombing planes, and, it was even said, one of the immense Italian fliers. This last was a craft capable of carrying several men and a quantity of supplies and ammunition.
Very soon, then, Tom Raymond and Jack Parmly were on their way to Paris again, accompanied by their comrades, and all would soon be engaged in the difficult and perilous task of finding the new German long-range cannon.
"I suppose you'll make another attempt to find your father?" suggested Jack to his chum, as they rode in on the train.
"Indeed I shall, if I have time. I can't understand why I haven't had some word before this. There are several possible reasons, of course. If it wasn't that we know he got to Rue Lafayette I'd say his ship had been sunk 'without a trace,' as the Germans ordered in other cases. But, of course, he safely reached this side. Then he just seems to have dropped out of sight, for I can't believe he was killed when the shell from the big gun hit the house where he had taken lodging. He may have found it advisable to return home at once, for some reason, and didn't have a chance to leave any word for me, or send me any message. And perhaps he hasn't got back to America yet. Then, too, he may be in Germany, a prisoner."
"Let us hope not," said Jack, softly, and Tom echoed the wish.
Much as he wished he could devote some time to the search for his father, Tom realized that he was working under military orders, and, however dear his father was to him, the sacrifice of his personal affairs must be made. He knew he would only have time to make some brief inquiries, and then he and Jack must go with the squadron to the headquarters assigned to it, as near the location of the big German gun as possible, and there try to silence it.
The train the picked squadron was traveling on was late, and it was dusk when they alighted at the railroad station.
"Think we'll have a chance to see anything of the bombardment?" asked Boughton.
"I was going to say I hoped not," answered Tom, "for I wish the beastly gun, or guns, would blow up. But that would take away our chance to pot 'em, and I know we all want to do that. You may see something, though they don't bombard at night as often as they do by day. Of late, however, before we left, the night firing was more frequent. Possibly they have found some means of hiding the gun flashes or of letting them mingle with others along a line so the exact location of the big Bertha is a matter of doubt."
As they alighted from the train, and were about to seek some taxicabs to take them to lodgings that had been assigned them, they all became aware of the fact that something unusual was going on. Suddenly the electric lights went out, leaving the region about the station, and indeed all of Paris, in comparative darkness.
At the same time a motor fire engine rushed screeching through the streets, giving an alarm.
"What is it?" cried Boughton. "Is the big gun firing?"
"It's a Zeppelin raid! I was here once before when they had one," said the Englishman coolly. "Mind your heads, boys. Just our rotten luck not to have a machine to go up after it."
He hurried out into the open street where he could have a view of the sky, and the others followed. There was more excitement than during the bombardment of the big gun. People were rushing here and there in search of safe places, and taxicabs, with their lamps like fireflies in the darkness, were skidding hither and yon, their horns calling for a clear way.
Suddenly there was a muffled roar, at some distance off. This was followed by a hoarse murmur, as though a burst of rage from many throats at the unspeakable outrage of the Huns in killing women and children.
At the same time the anti-aircraft guns, with which Paris is so efficiently guarded, began to bark and to send their red flashes out into the blackness of the night. They were shooting at the Zeppelin, as yet unseen by the men of the picked squadron, and the gunners aimed according to instructions sent them by wireless from scouts hovering in the air above the city.
As soon as word comes from the front, about eighty miles from Paris, that a Zeppelin is on its way to raid, an elaborate system of defense is put into operation. There are some airmen above Paris all the while, frequently as many as forty on sentry duty. But when word comes of a Zeppelin raid the whole squadron, numbering close to three hundred, goes aloft. By their searchlights, aided by those on the surface, these fliers endeavor to pick up the German machine, and, too, they endeavor to get near enough to attack it.
This was what was now going on. Pandemonium appeared let loose, and the explosion of the German bombs, mingling with the noise of the French guns, made Paris seem like a battlefield. Occasionally could be heard, when the guns were silenced for a moment, the roar of the many aeroplane motors aloft.
The Zeppelin seemed to be over a section of Paris near the Tuileries, judging by the bursts of light in that direction. Tom, Jack, and their friends wished with all their hearts that they might take a hand in the defense, but it was not to be. For perhaps half an hour the anti-aircraft guns roared out their defiance to the Hun, and then a large flare of gasolene was lighted in a public square.
This was a signal for the aeroplanes to return, for the Zeppelin had left, either because she found the situation too perilous for her, or because she had used up all her bombs.
The lights were turned on again, and the new arrivals watched the aeroplanes returning one by one, being recognized by their lights in the air as they moved about like gigantic illuminated insects.
"Well, that's some excitement," observed Tom, as he and the others finally succeeded in getting cabs, and started for their destination. "I hope no one was killed."
But the bombs of the inhuman Huns had found several marks, and while the harm from a military standpoint was small, a number of persons had been killed. Some damage had been inflicted on the Zeppelin, it was said later, one brave airman saying he got near enough to spray some bullets into one of the cabins where a crowd of officers and men were working the machine.
"We will be with you a little later," said Tom to the other members of the squadron, as, having reached their lodgings, the two chums set out.
"Where are you going?"
"To call on some ladies," answered Jack, for he and Tom had planned to see Bessie and her mother.
They reached their own former stopping place, to which they had been sent by Major de Trouville, but when they inquired for the Gleasons the landlady, who remembered the boys, stared at them in surprise, and said:
"Why, Madam Gleason and her daughter are not here! They went out this morning to meet you, and have not come back!"
"To meet us?" gasped Jack.
"Yes, in answer to your note bidding them do so!"
Tom and Jack gazed blankly at one another. The same thought was in the minds of both.
"The spy!"
"That's who did it," declared Tom. "He forged our names to a note—no hard task since neither Bessie nor her mother knows our writing very well—and he's induced them to go some place where he could get them in his power again."
"But why?" asked Jack.
"Probably because Potzfeldt wanted him to do it. He still has his eye on Mrs. Gleason's property, I presume, if there is any left after his robbery."
"It certainly is tough to think that Bessie and her mother have again fallen into his clutches!" exclaimed Jack. "And we can't do a thing to rescue them. We've got to report with the others in the morning at the new aerodrome."
"Yes, but we still have to-night free!" cried Tom. "It will give us several hours to make a search, and we'll do it! Do you know where Mrs. Gleason and Bessie went in response to this forged note?" he asked the landlady.
She mentioned a certain restaurant, not far away, where Tom and his chum had frequently eaten with Mrs. Gleason and her daughter.
"She was rather surprised to get the note from you," said the landlady, "and wondered why you didn't come yourself. But she supposed it had something to do either with your search for your father or with war matters, so she did not question the messenger. I heard her mention the place where she and Bessie were going, or I would not know."
"How long ago was it?" asked Jack.
"Oh, just before luncheon time. And they haven't come back."
"The scoundrels have a long start of us!" exclaimed Jack. "We'll have to do the best we can."
"Better notify the police at once," suggested Tom. "We'll need their help."
"That's right," agreed his chum.
Their uniform was an open sesame to the police officials, and a detective was at once detailed to go with the boys to the restaurant. There, as might have been expected, there was no news. The spy, or whoever Potzfeldt's agent was, had been too clever for that. All that could be learned from a taxicab driver was that a lady and a girl, answering the descriptions of Bessie and her mother, had been met in front of the restaurant by a man.
The three, after a short talk, had driven off together in an automobile, and that was the last seen of them.
"But we'll get some trace," declared the detective. "It is hard to get in or out of Paris now without proper papers. And while, of course, this spy may have forged documents, there is a chance that we may intercept him and help your friends. Time is against us, but we will do our best."
Tom and Jack knew that. There was nothing else to do, and so, worried as they were, they went back to their comrades. Tom made some inquiries about his father, but, as he feared, no news had come.
As may be imagined Tom and Jack did not pass a very restful night. The Zeppelin raid had set their nerves on edge, as well as those of every one else, and it could not be told when the big gun might begin firing again. Then the fact of Mrs. Gleason and Bessie being missing, and not knowing in what danger they might be, added to the boys' anxiety.
They paid a late visit to the police, hoping for news, but the spy had not been apprehended. Then they hurried back to get a little rest before starting with their comrades of the air to search for the monster gun.
While these events were transpiring, the French army intelligence department had not been idle. The officials knew how vitally necessary it was, in order not to have the morale of the people of Paris weakened, to do something to find and silence the big guns. And first it was necessary to discover them.
While this, as yet, had not been done with exactness, owing to the concealing tactics of the Germans, it was believed that the long-range cannon was hidden in a certain wood near Laon. French airmen had endeavored to spy out certain positions there, but an unusually large number of German planes had fought them off.
"That's pretty good evidence that there must be something doing," observed Tom, when he heard this information. "Laon is about ten miles behind the German lines as they exist at present. Just a breather for a good French plane. Jack, that's a trip we'll soon be taking."
"I'll be with you, old scout. How's your hand?"
"Oh, all right now. I can hold the joy stick or work the gun. I'm ready for whatever comes along."
The time had come for the picked squadron to leave Paris and assemble at the aerodrome assigned to them as their headquarters while the search for the big gun was in progress. Sad at having to leave without having some word of Mr. Raymond, and without knowing the fate of Bessie and her mother, Tom and Jack, nevertheless, bore up well and left with their comrades, going out of Paris on a train that would eventually bring them to their headquarters.
In a way their mission was a secret one. Yet it was a question if the Germans did not guess that something like what really was afoot would be undertaken in order to silence the super-cannon. They were up to all the tricks of war, and they must have realized that the French would do as the Germans themselves would do under similar circumstances.
"Well, this sure is some place!" exclaimed Tom, as they reached the camp where they were to stay until the gun had been destroyed, or until some other change in plans was necessary. "It's the best aerodrome we've struck since we began flying in this war."
"I believe you!" echoed Jack.
The place, though newly established just back of the French lines, where they opposed the German trenches, was well fitted up for the purpose to which it was to be devoted.
There were a number of canvas hangars for the aeroplanes, there were living quarters for the men, a wireless station and a well defended camp where the aviators might live in comfort during the periods between their flights.
Of course the place was open to attack by German fliers, but this was true of every place along the line. Sufficient camouflaging had been done, however, to render the spot reasonably secure from bombing. Of course a direct attack from in front would be met by the admirable French system of defense, and there were plenty of reserves that could be brought up if a general advance were attempted by the Germans. But as there was no particular place of any military or strategic importance on that sector, the worst that was to be feared was an attack from the air.
And this would be guarded against both by the French fliers themselves and by a battery of the newest type of anti-aircraft gun.
"They don't seem to have forgotten much," observed Tom, as he and Jack, with the others, went to the quarters assigned to them.
"You said something!" exclaimed Jack, admiringly.
Thus had been set up in this locality, where heretofore no aircraft activities had been carried on to any extent, a most perfect escadrille.
It was designed to destroy the big German cannon. Would it succeed?
That was a question every man of the Allies asked.
Shortly after the arrival of the picked squadron at the camp, which, in honor of Tom and Jack had been named "Lincoln," word came in over the wireless that the big gun had again fired on Paris.
"It's funny we didn't hear any report of it," said Jack.
"There have been reports enough," Tom remarked. "I've heard the booming of distant guns ever since we got near this place. Any one of them may have been the monster, or they may have been firing other guns to hide the sound of this cannon. Then, too, it may not make as much noise as we think it ought to. The Germans may have found a new kind of powder, or even some propelling gas, that makes no extraordinary report. In that case we couldn't locate the gun by the sound."
"Maybe you're right," agreed Jack. "Anyhow they're firing, that much is proved; and it's somewhere over there," and he motioned toward the German lines.
Much as the airmen desired to start at once in their search for the monster cannon, it was deemed wise to have first a consultation and a general understanding of what means should be employed.
Then, too, all the aircraft were new, having been shipped to Camp Lincoln and there assembled, and it was desired to test them before taking the dangerous flights over the German lines. So the airmen would have to spend some time—perhaps half a week—in preliminary work.
Meanwhile the great cannon would keep up its deadly, though, from a military standpoint, useless work.
And so began the preparation, if such it might be called. Every one, from the most daring "ace" to the humblest kitchen helper in the camp, was anxious for the day when it could be said that the gun was out of commission, or guns, if, as was likely, there was more than one. But the men in command knew the value of thoroughness. There must be no failure through lack of making proper plans.
But at last everything was in readiness. The planes had been tested, keyed up, and the motors run until every part of them was humming like a top. Each man felt confidence, not only in himself but in his craft, and that meant much. There were several types for the fliers to use, single-seaters, the big bombing craft, those equipped for slow flying and from which photographs were to be taken, as well as others. The taking of photographs was expected to help in revealing the position of the hidden gun.
The big Italian plane was not ready, it seemed, to be used, but it would be soon, it was said.
Then came the day and the hour when certain members of the picked squadron were to take the air to look for the gun. Tom and Jack, to their delight, were selected to go.
"What a chance!" exclaimed Jack, as he climbed into his machine, and saw that he had plenty of ammunition for the Lewis gun.
"I hope we can make good!" returned Tom.
Then they were away and up, seeking to find the monster cannon that was bringing the war into the heart of Paris.
For some little time the picked squadron that was intrusted with the difficult and dangerous task of locating the big German gun flew over the French lines. Below them Tom and Jack could make out various French camps, the front and supporting lines of trenches, and various other military works. They could see a brisk artillery duel going on at one point. They noted the puffs of smoke, but of course could not hear the explosions, as their own motors were making too much noise.
Tom and Jack kept within sight of one another, and also within view of their comrades. Each plane was marked with a big number so it could be distinguished, for the aviators themselves were so wrapped in fleece-lined clothes, so attired in gauntlets, goggles and fur boots, as protection against the terrible cold of the upper regions, that one's closest friend would not recognize him at a near view.
It was the object of this first scouting expedition to make a preliminary observation over as wide a range of the enemy's country as possible. While it was hoped that the location of the big gun might be spied out, it was almost too much to expect to pick out the spot at the first trial. The Germans were keen and wary, and undoubtedly they would have laid their plans well.
"Well, I don't see any of 'em coming out to dispute our passage," thought Tom, as he looked at his controls and noted by his height gage that he was now up about two miles. "There isn't a Boche plane in sight."
And the same thing was observed by Jack and the other fliers. The Germans seemed to be keeping down, or else were higher up, or perhaps hidden by some cloud bank.
That was another hazard of the air. Going into a cloud, or above it might mean, on coming out, that one would find himself in the midst of enemies.
It is a life full of dangers and surprises. It is this which makes it so appealing to the young and brave.
On and on flew the Allied planes, and the eager eyes of the pilots were alternately directed toward the earth and then ahead of them, and upward to discern the first sight of a Hun machine, if such should venture out.
The fliers were now well over the German lines, and the batteries from below began firing at them. This was to be expected, and Tom, Jack and the others had gotten used to the bursts of shrapnel all around them. They could see the puffs of smoke where the shells burst, but they could hear no sounds.
"The 'Archies' are busy this morning," thought Jack, as he noted the firing from below, and using the French slang word for the German anti-aircraft guns.
He took a quick glance toward Tom's machine to make sure his chum, so far, was all right. Assured on this point Jack looked to his own craft.
"Well," he mused, "at this point the 'flaming onions' can't get us, but they may pot us as we go down, as we'll have to if we want to get a good view of the ground where the big gun may be hidden."
The "flaming onions," referred to by Jack, were rockets shot from a ground mortar. They have a range of about a mile, and when a series of them are shot upward in the direction of a hostile plane it is no easy matter for the aviator to pass through this "barrage." Once a "flaming onion" touches an aeroplane the craft is set on fire, and then, unless a miracle happens, the aviator falls to his death.
The German gunners, however, could not use these to advantage while the French planes kept so high up, though the shrapnel was a menace, for the Hun guns shot far and with excellent aim. A number of the scout machines were hit, Tom's receiving three bullets through the wings, while Jack's engine was nicked once or twice, though with no serious damage.
But as for the German planes they declined the combat that was offered them. Probably they had different plans in view. It soon became evident to Tom, Jack and the others that to fly at that height meant discovering nothing down below. The distance was too great. The big gun might be hidden almost anywhere below them, but until it was fired, disclosing its presence by an unusual volume of smoke, it would not be discovered. Also its fire might be camouflaged by a salvo from a protecting battery.
"It's about time he did that," said Tom to himself at last, as he noticed Cerfe, who was the leader of the air squadron, dip his plane in a certain way, which was the signal for going down. "We've got to get lower if we want to see anything," the young aviator went on. "Though they may pot some of us."
Down they went, flying comparatively low but at great speed in order to offer less of a target to the gunners below them. And, following instructions, each pilot noted carefully the section of the German trenches beneath him, and the area back of them. They were seeking the big gun.
But, though they looked carefully, it could not be seen, and finally when one of the French machines was badly hit, and the pilot wounded, so that he had to turn back toward his own lines, Cerfe gave the signal for the return.
In all this time not a Hun plane had come out to give battle. What the reason for this was could only be guessed at. It may have been that none of the German machines was available, or that skillful pilots, capable of sustaining a fight with the veterans of the French, were not on hand just then. However that may have been, Tom, Jack and the others, after firing a few rounds from their machine guns at the trenches, though without hope of doing much damage, turned back toward Camp Lincoln.
"Well, then you did not discover anything?" asked Major de Trouville, who had been transferred and given the command at Camp Lincoln.
"Nothing," answered Jack.
"If it's in the section we covered, it is well hidden," added Tom.
"And I think, don't you know," went on the Englishman, Haught, "that the only way we'll be able to hit on the bally mortar is to fly low and take photographs."
"That's my idea," said the major. "If we take a series of photographs we can develop them, enlarge them, if necessary, and examine them at our leisure. I had thought of this, but it's a slow plan, and it means—casualties. But I suppose that can't be avoided. But I wanted to try the scouting machines first.
"After all, the taking of photographs from the air of the enemy trenches and the land behind them is a most valuable method of getting information," he continued.
Men, specially trained for such observation work, examine the photographs after the aviators return with the films, and they can tell, by signs that an ordinary person would pass over, whether there is a new battery camouflaged in the vicinity, whether preparations are under way for receiving a large number of troops, or whether a general advance is contemplated. Then measures to oppose this can be started. So, Major de Trouville was right, photography forms a valuable part of the new warfare.
The photographing of the enemy positions is done in big, heavy machines, carrying two men. They must fly comparatively low, and have not much speed, though they are armed, and it takes considerable of an attack to bring them down. But of course the pilot and his observer are in danger, and, to protect them as much as possible, scout planes—the single-seat Nieuports—are sent out in squadrons to hover about and give battle to the German aircraft that come out to drive off the photographers.
"We'll undertake that," proceeded Major de Trouville. "I'll order the big machine to get ready for an attempt to-morrow at locating the gun."
"Is it still shooting?" asked Jack.
"Yes, it has just been bombarding Paris; but I have no reports yet as to the damage done."
"Aren't we doing anything at all?" asked Tom.
"Oh, yes, our batteries are keeping up a fire on the German lines along the front behind which we think the gun is concealed, but what the results are yet, we don't know."
"Well, let's hope for clear weather to-morrow," suggested Boughton.
The intervening time was occupied by the aviators in getting everything in readiness. The machines were inspected, the automatic guns gone over, and nothing left undone that could be thought of to give success.
The next day dawned clear and bright, and, as soon as it was light enough to make successful photographs, the big machine set out, while hovering above and to either side of it were several Nieuports. Tom and Jack were each occupying one of these, ready to give battle to the Huns above or below the clouds.
In order to distract the attention of the Germans as much as possible from the direct front where the airships were to cross the lines, a violent artillery fire was maintained on either flank. To this the Germans replied, perhaps thinking an engagement was pending. And so, amid the roar of big guns, the flying squadron got off.
"Now we'll see what luck we'll have," mused Tom, as he drove his machine forward, being one of the large aerial "V" that had for its angle the ponderous photographing bi-motored machine.
Over the German lines they flew, and then the Germans awoke to the necessity of ignoring the fire on their flanks and began shooting at the airships over their heads.
"This ought to bring out their pilots if they have any sporting blood," thought Jack.
And it did. The French and their allies were no more than well over German-occupied territory, before a whole German air fleet swarmed up and advanced to give battle. They flew high, intending to get above their enemies, and so in the most favorable fighting position. But Tom, Jack and the others saw this, and also began to elevate their planes.
"We certainly are going up!" mused Tom, as he noted the needle of his height gage showing an altitude of twelve thousand feet. "When are they going to stop? We're high above the clouds now."
That was true as regarded himself, Jack, and two other French planes. But still the Germans climbed. Doubtless some of them were engaging the big machine which was low down, trying to take photographs, but Cerfe and Boughton were guarding that.
"Here comes one at me, anyhow!" thought Tom, as he saw a Hun machine headed for him.
"Well, the sooner it's over the better. Here goes!" and he pressed the release of his automatic gun, meanwhile heading his craft full at the German to direct the fire, for that is how the guns are aimed in a Nieuport, the gun being stationary.
And so began the battle above the clouds.
Tom Raymond's first few shots went wild, as he noted by the tracer bullets. Then, steering his machine with his feet, he brought it around a trifle, and, having by a quick action risen above his antagonist, he let him have a good round, full in the face. The result was disastrous to the German, for suddenly the Hun machine burst into flames, the gasolene from the punctured tank burning fiercely, and down it went a flaming torch of death.
Tom felt some bullets whistle around him, and one exploded as it struck part of his engine, but without injuring it.
"Explosive bullets, are they?" mused the young aviator. "Against all the rules of civilized warfare. Well, he won't shoot any more," he thought grimly.
But though Tom had come victorious from his engagement with his single antagonist, he had no sooner straightened out and begun to take stock of the situation, than he became aware that he was in great danger. Above him, and coming at him with the swiftness of the wind, were two speedy German machines, bent cm his destruction.
They were both firing at him, the angles of attack converging, so that if one missed him the other would probably get him.
"I've got to get out of this," Tom reasoned. He headed his plane toward the antagonist on his right, shooting upward and firing as rapidly as he could, and had the satisfaction of seeing the German swerve to one side. The fire was too hot for his liking.
The other, however, came on and sent such a burst of fire at Tom that the latter realized it was a desperate chance he was taking. He tried to get above his enemy, but the other's plane was the speedier of the two, and he held the advantage.
Tom's ammunition was running low, and he realized that he must do something. He decided to take a leaf out of the book of the Germans.
"I'll go down in a spinning nose dive," he reasoned. "They'll be less likely to hit me then. I'll have to go back, I guess, and get some more shots. I used more than I thought."
He sent his last drum at the persistent German, and, noting that the other was swooping around to attack again, went into the dangerous spinning nose dive.
The Germans may have thought they had disabled their antagonist, for this dive is one a machine often takes when the pilot has lost control. But in this case Tom still retained it, and when he had dropped out of the danger zone, he prepared to straighten out and fly back over his own lines.
It is not easy to straighten an airplane after such a dive, and for a moment Tom was not sure that he could do it. Often the strain of this nose dive, when the machine is speeding earthward, impelled not only by its propellers, but by the attraction, of gravitation, is so great as to tear off the wings or to crumple them. But after one sickening moment, when the craft seemed indisposed to obey him, Tom felt it beginning to right itself, and then he started to sail toward the French lines.
He was not out of danger yet, though he was far enough away from the two German machines. But he was so low that he was within range of the German anti-aircraft guns, and straightway they began shooting at him.
To add to his troubles his engine began missing, and he realized that it had sustained some damage that might make it stop any moment. And he still had several miles to travel!
But he opened up full, and though the missing became more frequent he managed to keep the motor going until he was in a position to volplane down inside his own lines, where he was received with cheers by his comrades of the camp.
"How goes it?" asked Major de Trouville anxiously.
"I think we are holding them off," said Tom.
He was the first one who had had to return, much to his chagrin. He leaped out of his craft, and was about to ask for another to go back and renew the battle of the clouds, when he saw the big photographing machine returning, accompanied by all but two of the escorting craft.
"A pair missing," murmured the major, as he searched the sky with his glasses.
And Tom wondered if Jack's machine was among those that had not headed back.
Eagerly he procured a pair of binoculars, and when he had them focused he identified one machine after another, at last picking out his chum's. It did not seem to be damaged.
But two of the French craft had been brought down—one in flames, the report had it, and the other out of control, and both fell within the German lines.
"Did you get any photographs of the big gun?" asked the major, when the men in the double machine had made a landing.
"We got lots of views," answered the photographer, "but what they show we can't say. As far as having seen the gun goes, we didn't spot it."
"Well, maybe the photographs will reveal it," suggested the major. "Ah, but I am sorry for the two that are lost!"
Jack's experience had been less exciting than Tom's. One machine had attacked the former, and there had been a hot engagement for a while, but the German had finally withdrawn, though to what extent he was wounded or his machine damaged Jack did not know.
However, the picked squadron had reason to feel satisfied with their efforts. All now depended on the developing of the photographs, and this was quickly done. For this part of warfare is now regarded as so important that it is possible for a plane to fly over an enemy's station, take photographs and have prints in the hands of the commanding officer inside of an hour, if all goes well.
Carefully the photographs were examined by men expert in such matters. Eagerly they looked to discover some signs of the emplacement of the big gun. But one after another of the experts shook his head.
"Nothing there," was the verdict.
"Then we've got to try again," decided Major de Trouville. "We must find that gun and destroy it!"
"Well, we're ready," announced Tom, and the others of the picked squadron nodded in assent.
And then began an organized campaign to locate the monster cannon. It continued to fire on Paris at intervals. Then three days went by without any shells falling, and the rumor became current that the gun had burst. If this had happened, there was another, or more, to take its place, for again the bombarding of the city began.
Meanwhile the air scouts did their best to find the place of the firing. Hundreds of photographs were taken, and brave scouts risked death more than once in flying low over suspected territory. But all to no purpose. Several were killed, but others took their places. Jack was hit and so badly wounded that he was two weeks in the hospital. But when he came out he was again ready to join Tom in the search.
No word came as to the whereabouts of Bessie and her mother, nor did Tom hear anything of his father. The lack of information was getting on the nerves of both boys, but they dared not stop to think about that, for the army needed their best efforts as scouts of the air, and they gave such service gladly and freely.
Every possible device was tried to find the location of the German gun, and numerous battles above the clouds resulted at different times during the scout work.
On the whole the advantage in these conflicts lay with the armies of the Allies, the Germans being punished severely. Once a German plane was brought down within the French lines, and its pilot made a prisoner.
It was hoped that some information might be gotten out of the German airman that would lead to the discovery of the big gun, but, naturally, he did not reveal the secret; and no more pressure was brought to bear on him in this matter than was legitimate. The hiding place of the gun remained a secret.
Its possible size and the nature of its shooting was discussed every day by Tom, Jack and their comrades. In order to make a cannon shoot a distance of about eighty miles it was known that it was necessary to get the maximum elevation of forty-five degrees. It was also calculated that the shell must describe a trajectory the highest point in the curve of which must be thirty-five miles or more above the earth. In other words the German cannon had to shoot in a curve thirty-five miles upward to have the missile fly to Paris. Of course at that height there was very little air resistance, which probably accounted for the ability of the missile to go so far. That, and the sub-calibre shell, made the seemingly impossible come within the range of possibility.
"What are you going to do, Tom?" asked Jack one evening, after an unsuccessful day's flight. For Tom was going toward his hangar.
"Going up."
"What for?" Jack went on.
"Oh, no reason in particular. I just feel like flying. We didn't do much to-day. Had to come back on account of mist, and we didn't see enough to pay for the petrol used. Want to come along?"
"Oh, I might, yes."
Tom and Jack went up, as did several more. But the two remained up longer than did the others, and Jack was somewhat surprised to see his chum suddenly head for the German lines, but at an angle that would take him over them well to the south of where the observation work had been carried on.
"I wonder what he's up to," mused Jack; "Guess I'd better follow and see."
There was not much chance of an aerial battle at that hour, for dusk was coming on. There had been no bombing squadron sent out, which would have accounted for Tom going to meet them, and Jack wondered greatly at his chum's action.
Still there was no way of asking questions just then, and Jack followed his friend. They sailed over the German lines at a good height, and Jack could keep Tom in view by noting the lights on his plane.
These were also seen by the Germans below, and the anti-aircraft guns began their concert, but without noticeable effect. None of the Hun airmen seemed disposed to accept a challenge to fight, so Tom and Jack had the upper air to themselves.
Below them the boys could see flashes of fire as the various guns were discharged; and at one point in the lines there was quite an artillery duel, the French batteries sending over a shower of high explosive shells in answer to the challenge from the Boches.
It was not until Jack had followed his chum back to Camp Lincoln, and they had made a landing, that a conversation ensued which was destined to have momentous effect.
"Jack, did you notice the peculiar colored lights away to the north of where we were flying?" asked Tom, as they divested themselves of their fur garments.
"You mean the orange colored flare, that turned to green and then to purple?" asked Jack.
"That's it. I thought you'd see it. I wonder what it means?"
"Oh, perhaps some signal for a barrage or an attack. Or they may have been signaling another battery to try to pot us."
"No, I hardly think so. They didn't look like signal fires. I must ask Major de Trouville about that."
"What?" inquired the major himself, who was passing and who heard what Tom said.
"Why, we noticed some peculiar lights as we were flying over the German lines in the dark. There was an orange flare, followed by a green light that changed to purple," answered Tom.
"There was!" cried the major, seemingly much excited. "You don't mean it! That's just what we've been hoping to see! Come, you must tell Laigney about this."