One glance at the bulletin board, erected just outside their quarters at the aerodrome, told Tom and Jack what they were detailed for that day. It was the day following the arrival of Nellie Leroy at that particular place in France, only to find that her brother was missing—either dead, or alive and a prisoner behind the German lines.

“Sergeant Thomas Raymond will report to headquarters at eight o'clock, to do patrol work.”

“Sergeant Jack Parmly will report to headquarters at eight o'clock for reconnaissance with a photographer, who will be detailed.”

Thus read the bulletin board, and Tom and Jack, looking at it, nodded to one another, while Tom remarked:

“Got our work cut out for us all right.”

“Yes,” agreed Jack. “Only I wish I could change places with you. I don't like those big, heavy machines.”

But orders are orders, nowhere more so than in the aviation squad, and soon the two lads, after a hearty if hasty breakfast, were ready for the day's work. They each realized that when the sun set they might either be dead, wounded or prisoners. It was a life full of eventualities.

A little later the two young airmen, in common with their comrades, were ready. Some were to do patrol work, like Tom—that is fly over and along the German lines in small swift, fighting planes, to attack a Hun machine, if any showed, and to give notice of any attack, either from the air or on the ground. The latter attacks the airmen would observe in progress and report to the commanders of infantry or batteries who could take steps to meet the attack, or even frustrate it.

Tom was assigned to a speedy Spad machine, one of great power and lightness into which he climbed. He was to fly alone, and on his machine was a machine gun of the Vickers type, which had to be aimed by directing, or pointing, the aeroplane itself at the enemy.

After Tom had given a hasty but careful look at his craft, and had assured himself of the accuracy of the report of his mechanician that it had oil and petrol, his starter took his place in front of the propeller.

“Well, Jack,” called Tom to his chum, across the field, where Jack was making his preparations for taking up a photographer in a big two-seated machine, “I wish you luck.”

“Same to you, old man. If you see anything of Harry, and he's alive, tell him we'll bring him back home as soon as we get a chance.”

“Do you think there is any chance?” asked Tom eagerly. “I wouldn't want anything better than to get Harry away from those Boches—and make his sister happy.”

“Well, there's a chance, but it's a slim one, I'm afraid,” remarked Jack. “We'll talk about it after we get back. Maybe there'll be a message from the Huns about him before the day is over.”

“I hope so,” murmured Tom. “If those Huns only act as decently toward us as we do toward them, we'll have some news soon.”

For it is true, in a number of instances that the German aviators do drop within the allied lines news of any British, French or American birdman who is captured or killed inside the German lines.

“All ready?” asked Tom of his helper.

“Switch off, gas on,” was the answer.

Tom made sure that the electrical switch was disconnected. If it was left on, in “contact” as it is called, and the mechanician turned the propeller blades, there might have been a sudden starting of the engine that would have instantly kill the man. But with the switch off there could be no ignition in the cylinders.

Slowly the man turned the big blades until each cylinder was sucked full of the explosive mixture of gasoline and air.

“Contact!” he cried, and Tom threw over the switch.

Then, stepping once more up to the propeller, the man gave it a pull, and quickly released it, jumping back out of harm's way.

With a throbbing roar the engine awoke to life and the propeller spun around, a blur of indistinctness. The motor was working sweetly. Toni throttled down, assured himself that everything was working well, and then, with a wave of his hand toward Jack, began to taxi across the field, to head up into the wind. All aeroplanes are started this way—directly into the wind, to rise against it and not with it. On and on he went and then he began to climb into the air. With him climbed other birdmen who were to do patrol and contact work with him, the latter being the term used when the airship keeps in contact through signaling with infantry or artillery forces on the ground, directing their efforts against the enemy.

Having seen Tom on his way, Jack turned to his own machine. As his chum had been, Jack was dressed warmly in fur garments, even to his helmet, which was fur lined. He had on two pairs of gloves and his eyes were protected with heavy goggles. For it is very cold in the upper regions, and the swift speed of the machine sends the wind cutting into one's face so that it is impossible to see from the eyes unless they are protected.

Jack's machine was a two-seater, of a heavy and comparatively safe type—that is it was safe as long as it was not shot down by a Hun. Jack was to occupy the front seat and act as pilot, while Harris, the photographer he was to take up, sat behind him, with camera, map, pencil and paper ready at hand for the making of observations.

On either side of the photographer's seat were six loaded drums of ammunition for the Lewis gun, for use against the ruthless Hun machines. Jack had a fixed Vicker machine weapon for his use.

“Hope I get a chance to use 'em,” said Harris with a grin, as he climbed into his seat, patted the loaded drums, and nodded to Jack that he was ready.

The same procedure was gone through as in the case of Tom. The man spun the propeller, and they were ready to set off. Accompanying them were two other reconnaissance planes, and four experienced fighting pilots, two of them “aces,” that is men who, alone, had each brought down five or more Hun planes. The big planes, used for obtaining news, pictures, and maps of the enemy's territory, are always accompanied by fighting planes, which look out for the attacking Germans, while the other, and less speedy, craft carry the men who are to bring back vital information.

“Let her go!” exclaimed Harris to Jack, and the latter nodded to the mechanician, who, after the order of “contact,” spun the blades again and they were really off, together with the others.

Up and up went Jack, sending his machine aloft in big circles as the others were doing. Before him on a support was clamped a map, similar to the one supported in front of Harris, and by consulting this Jack knew, from the instructions he had received before going up, just what part of the enemy's territory he was to cover. He was under the direction of the photographer and map-maker, for the two duties were combined in this instance.

Up and up they went. There was no talking, for though this is possible in an aeroplane when the engine is shut off, such was not now the case. But Jack knew his business.

His indicator soon showed them to be up about fourteen thousand feet, and below them an artillery duel was in progress. It was a wonderful, but terrible sight. Immediately under them, and rather too near for comfort, shrapnel was bursting all around. The “Archies,” or anti-aircraft guns of the Germans, were trying to reach the French planes, and, in addition to the bullets, “woolly bears” and “flaming onions” were sent up toward them. These are two types of bursting shells, the first so named because when it explodes it does so with a cloud of black smoke and a flaming center. I have never been able to learn how the “onions” got their name, unless it is from the stench let loose by the exploding gases.

Though they were fired at viciously, neither Jack nor his companion was hit, and they continued on their way, keeping at a good height, as did their associates, until they were well over the front German lines.

Jack noticed that some of the other planes were dropping lower, to give their observers a chance to do their work, and, in response to a shove in his back from the powerful field glasses carried by Harris, Jack sent his machine down to about the nine-thousand-foot level. By a glance at the map he could see that they were now over the territory concerning which a report was wanted.

They were now under a heavy fire from the German anti-aircraft guns, but Jack was too old a hand to let this needlessly worry him. He sent his machine slipping from side to side, holding it on a level keel now and then, to enable Harris to get the photographs he wanted. In addition, the observer was also making a hasty, rough, but serviceable map of what he saw.

Jack glanced down, and noted a German supply train puffing its way along toward some depot, and he headed toward this to give Harris a chance to note whether there were any supplies of ammunition, or anything else, that might profitably be bombed later. He also saw several columns of German infantry on the march, but as they were not out to make an attack now, they had to watch the Huns moving up to the front line trenches, there later, doubtless, to give battle.

Back and forth over the German lines flew Jack, Harris meanwhile doing important observation work. As Jack went lower he came under a fiercer fire of the batteries, until, it became so hot, from the shrapnel bursts, that he fain would have turned and made for home. But orders were orders, and Harris had not yet indicated that he had enough.

Twisting and turning, to make as poor a mark as possible for the enemy guns, Jack sent his machine here and there. The other pilots were doing the same. Machine guns were now opening up on them, and once the burst of fire came so close that Jack began to “zoom.” That is he sent his craft up and down sharply, like the curves and bumps in a roller-coaster railway track.

By this time the leading plane gave the signal for the return, and, thankful enough that they had not been hit, Jack swung about. But the danger was not over. They had yet to pass across the enemy's front line trenches, and when Harris signaled Jack to go down low in crossing the lad wondered what the order was for. It was merely that the observer wanted to see what was going on there so he could report.

They went down to within a mile of the earth, and several times the plane was struck by pieces of shrapnel or bullets from machine guns. Twice flying bits of metal came uncomfortably close to Jack, but he was kept too busy with the management of his machine to more than notice them. Harris was working hard at the camera and the maps.

Then, suddenly, came the danger signal from the leading plane, and only just in time. Out from the German hangars came several battle machines. Harris dropped his pencil and got ready the automatic gun, but it was not needed, for, after approaching as though about to attack, the Huns suddenly veered off. Later the reason for this became known. A squadron of French planes had arisen as swiftly to give battle, and however brave the Hun may be when he outnumbers the enemy, he had yet to be known to take on a combat against odds.

So Jack and his observer safely reached the aerodrome again, bringing back much valuable information.

“Is Tom here yet?” was Jack's first inquiry after he had divested himself of his togs and men had rushed to the developing room the camera with its precious plates.

“Not yet,” some of his chums told him. “They're having a fight upstairs I guess.”

Jack nodded and looked anxiously in the direction in which Tom was last seen.

It was an hour before the scouting airplanes came back, and one was so badly shot up and its pilot so wounded that it only just managed to get over the French lines before almost crashing to earth.

“Are you all right, Tom?” cried Jack, as he rushed up to his chum, when he saw the latter getting out of his craft, rather stiff from the cold.

“Yes. They went at me hard—two of 'em but I think I accounted for one, unless he went into a spinning nose dive just to fool me.”

“Oh, they'll do that if they get the chance.”

“I know,” assented Tom. “Hello!” he exclaimed as he noticed a splintered strut near his head. “That came rather close.”

And indeed it had. For a bullet, or a piece of shrapnel, has plowed a furrow in the bit of supporting wood, not two inches away from Tom's head, though in the excitement of the fight he had not noticed it.

There had been a fight in the upper air and one of the French machines had not come home.

“Another man to await news of,” said the flight lieutenant sadly, when the report reached him. “That's two in two days.”

“No news of Leroy yet?” asked Tom and Jack, as they went out of headquarters after reporting.

“None, I am sorry to say. It is barely possible that he landed in some lonely spot and is still hiding out—if he is not killed. But I understand you two young men had something to request of me. I can give you some attention now,” went on the commander of their squadron.

“We want to be transferred!” exclaimed Tom. “Now, that Pershing's men are here—”

“I understand,” was the answer. “You want to fight with your countrymen. Well, I would do the same. I will see if I can get you transferred, though I shall much regret losing you.”

He was as good as his word, and a week later, following some strenuous fights in the air, Tom and Jack received notice that they could report to the first United States air squadron, which was then being formed on that part of the front where the first of Pershing's men were brigaded with, the French and British armies.

Du Boise, who had brought word back of the fate that had befallen Harry Leroy, sent for Tom and Jack when it became known that they were to leave.

“Shall I ever see you again?” he asked wistfully.

“To be sure,” was Tom's hearty answer. “We aren't going far away, and we'll fly over to see you the first chance we get. Besides, we're going to depend on you to give us some information regarding Leroy. If the Huns drop any message at all they'll do it at this aerodrome.”

“Yes, I believe you're right,” assented Du Boise, trying not to show the pain that racked him. “But it's so long, now, I begin to believe he must be dead, and either the Huns don't know it or they aren't going to bother to send us word. But I'll let you know as soon as I hear anything.”

“Is his sister here yet?” asked Jack, for Tom and he had been too busy the last two days, getting ready to shift their quarters, to call on Nellie Leroy.

“She has gone back to Paris,” answered Du Boise. “There was no place for her here. I can give you her address. I promised to let her know in case I got word about her brother.”

“I wish you would give me the address!” exclaimed Tom eagerly, and his chum smiled at his show of interest.