The first thing that Linda thought of when she opened her eyes the following morning was the glorious fact that she was now a real pilot. She could take her plane anywhere—to Green Falls, to her father's ranch in Texas, wherever she wanted to go—and nobody could stop her. The freedom of the world and of the skies was hers.

But she had no intention of taking it any farther than the Spring City Flying School that day. She would spend the morning there, watching one of the licensed mechanics give it a thorough inspection, in readiness for the flight to Green Falls on the following day.

She wished that it might be Ted Mackay who would go over the plane. She had such confidence in his knowledge, his thoroughness. Besides, it would be fun to spend the morning with him, asking him questions, and talking things over.

Naturally, that was impossible. When Linda reached the field she found that Ted already had gone, and a number of changes had been made. H. B. Taylor was now first-ranking instructor, and the young man who had been acting as office boy, or orderly, or whatever they chose to call him, had passed his course and was promoted to the rank of instructor. Another man took his place—an older man this time, and Linda thought probably it was the poor fellow who had been having engine trouble with his shabby coupÉ the preceding day. Everything seemed different, and Linda was somehow glad that she was leaving. The place would never be the same to her without Ted Mackay.

About noon she received the mechanic's O.K. upon her plane, and flew home in time for lunch. Her aunt had finished packing, and was as excited as a child about going to Green Falls, and again taking up their customary social life among their friends.

"I have bought a new flying suit for you, dear," she said to her niece, as the girl entered the library. "Unwrap it and see how you like it."

Linda eagerly unfastened the strings and lifted out a pair of white flannel knickers, with a jaunty blue sweater and helmet of knitted silk, just the color of her eyes. The whole costume was charming, and a lovely change from the dark riding breeches she had been using for flying.

"It's perfect, Aunt Emily!" she cried, realizing for the first time that she had never cared for what she was now wearing. "And it was so sweet of you to think of getting it for me!"

"I never could see why girls have to look masculine," replied her aunt. "Of course I can understand that skirts are impractical, but they make these suits so pretty now-a-days. And I want you to look nice the very first minute you arrive at Green Falls. First impressions are always so important and there is sure to be a crowd there to greet you."

Linda was only too delighted to wear it the next day, which dawned clear and warm for her flight. Miss Carlton left early in the morning, by train, so that she would be at Green Falls in plenty of time to welcome the flyers.

Ralph came over for Linda about half-past nine. Carrying their lunch, the young people started on their first real adventure in the air.

The young man, too, wore a new suit of spotless white flannel, and, as they walked, tall and slender and straight, they made perhaps the best-looking pair of flyers in America. But neither was conscious of that; both were too much excited about their first trip in the air to give even a passing thought to their appearances.

"Are you sure that you have the precious necklace?" asked Linda, as they made their way across the field in back of her house.

"Yes, indeed," answered Ralph. "I went to the safe-deposit vault this morning to get it. That was one reason why I didn't want to start early. I had to wait for the bank to open."

"Kit would be horribly disappointed if we didn't bring it," returned Linda. "I honestly think she loves those pearls as much as I do my 'Pursuit'!"

"Queer taste," remarked the boy. "If I had them, I'd sell them and buy a biplane!"

"Of course you would," said Linda approvingly. "Even if you do insist upon talking baby-talk!"

"Baby-talk?"

"Certainly. 'Buy a biplane'—sounds like 'Bye, Bye, Baby,' doesn't it?"

Ralph smiled, but they both forgot immediately what they were saying, for they were beside the plane now, ready to start on their flight. Linda was not at all nervous about the journey, only thrilled and happy. She climbed into the cockpit with the same assurance that she entered her car, and her take-off was just as easy, just as natural. It seemed now as if she piloted the biplane by instinct; with the sureness of a bird it rose into the air to a gradual height of fifteen hundred feet. For she had been cautioned again and again that there was safety in height.

They flew along without any attempt at conversation, for it was difficult to hear above the roar of the motor. But Linda was so happy that she hummed softly to herself, and most of the time she was smiling. Ralph, with a map in his lap, kept a close watch on the compass.

For some time they did not see any other planes in the sky, and then at last one came into view. As it drew closer, it occurred to Linda to wonder whether she was being followed.

"Who do you suppose that is?" shouted Ralph, above the noise of the motor.

"I think it's somebody from our school—maybe Taylor," she replied. "Perhaps Dad ordered them to follow us—for safety—or maybe it was Ted Mackay's idea."

As the plane drifted off to one side, they thought no more about the matter. But it was noon now; the sun stood high overhead, and both of the young people were astonished to find how hungry they were.

"I want to try a couple of stunts before we eat," Linda told Ralph. "You're game, aren't you?"

"Surest thing!" replied the boy, with delight. "We've got plenty of height—and a spectator too, for that matter." The other plane had just come back into sight.

Linda's eyes were shining with excitement, yet inside she was perfectly cool. Hadn't she made inside loops and Immelman turns often at school, and didn't she know exactly what to do? With perfect poise, she swung the plane into a loop, and completed it without any difficulty. Pleased with her success, she tried it again and again.

"You must think you're Laura Ingalls!" shouted Ralph, catching his breath. "Trying to beat her record?"

"Hardly," smiled Linda, for the famous aviatrix he mentioned held the record at that time with nine hundred and eighty consecutive inside loops, at a speed of four and a half loops a minute.

The plane was righted now, but Linda suddenly noticed that Ralph was acting awfully queer, hanging over the side, and hunting frantically in the pockets of the sweater which he had put over the seat. She believed he must be ill; certainly his face was ghastly white.

"Ralph!" she cried, fearfully. "What's the matter?"

"I've lost the necklace!" he screamed in terror. "Must have fallen out of my pocket!"

"Oh!" wailed Linda, aghast at the meaning of his words. "Are you sure?"

"Positive!"

"Then we'll land immediately. We're over a field, so we ought to be able to find it. Now—keep your eye on the compass!"

Gradually, and with easy skill, she turned the biplane into the wind and descended, finally coming down into a large flat field, evidently a pasture ground for some horses. Ralph was the first to jump out.

"We went a little south to land," he said, "so it must have dropped up there."

"Was it in a box?" questioned Linda.

"Yes, fortunately. A white velvet box, inside a larger pasteboard one, with three rubber bands around it. That ought to make it easier to find."

Linda, however, had her doubts; the field was so big! Besides, what proof had Ralph that he had lost it at that particular minute—when she was making her loops. She remembered that he had taken off his sweater an hour ago, when he felt too warm, and had carelessly hung it over the side, forgetful of the precious box in its pocket. That was the trouble with being so rich! Many times she had noticed how heedless both Kitty and Ralph were about valuables.

They walked silently across the field, their eyes on the ground, their minds filled with remorse. Ten minutes passed, and they had not found it.

"Let's go back and eat our lunch," suggested Ralph, consulting his watch. "It's almost one o'clock, and we'll feel better if we eat. After all, we have plenty of time—Green Falls is only about twenty miles farther. We could search all afternoon, if necessary."

"Yes, only Aunt Emily would nearly die of anxiety. She'd be sure we had been killed, if we didn't arrive before supper."

They went back to the plane and took out the dainty lunch which Miss Carlton's cook had packed that morning for them. But, hungry though they were, the meal was not the pleasant picnic they had been hoping for. Both were too unhappy to enjoy what they were eating.

Presently the noise of a motor overhead attracted their attention, and, looking up, they saw a plane in descent. When it was low enough to identify, they knew that it was the one that had been following them.

"It's the 'Waco' from our school!" cried Linda. "I recognize it now. He must think we're in trouble. I wonder who's piloting?"

The plane made a rather poor landing at the far end of the field, perhaps half a mile away. They could distinguish a man getting out of the cockpit, but of course at that distance they could not identify him. However, he seemed to be coming slowly towards them.

As he advanced nearer and nearer Linda noticed that he wore an ordinary suit of clothing—not a flyer's uniform, and he kept his hand in his pocket. But she still did not recognize him—unless he was that new man the school had taken on the preceding day. Once he stooped over, as if he were picking something up, and Linda's heart beat wildly with hope. Could it be that he had found the necklace? Apparently, though, it was only a plant that he had pulled up by the roots, for when he straightened himself, he seemed to be examining its leaves.

"In trouble?" he shouted, as soon as he was within hearing distance.

Ralph jumped up and ran towards him, shaking his head in the negative.

"No trouble with the plane," he replied. "But we've lost a little box—with a necklace in it. You haven't seen it, have you?"

"Why, yes," answered the man slowly, "I did pick up a box." And he put his other hand in his pocket, and drew out the very article. Fortunately it had not been broken; even the rubber bands were still tightly around it. He handed it to Ralph.

"Oh, thank you a thousand times!" cried Linda, too relieved to believe her eyes. "The necklace was a graduation present to this man's sister, and she values it very highly!"

"Well, if that's all, I'll be off," said the man, as he watched Ralph put the box into his pocket.

"No, I must reward you," insisted the boy, taking out a twenty-dollar bill. "And by the way, you're from the Spring City Flying School, aren't you? We recognized the plane."

The other nodded, and seemed in a hurry to be off. Already he was twenty feet away.

"It was awfully nice of you to follow us, and look after us," called Linda, "but really we don't need protection. We're getting along finely!"

But the man was running now, and could hardly have heard what Linda was saying. In a couple of minutes they heard the motor start, and with a clumsy take-off, the plane ascended.

"A queer cuss," remarked Ralph. "And I can't see that he's much of a flyer. You and I are both better—by a long shot.... But anyhow, we've got the necklace!" He put his arms around Linda and hugged her, and she was too happy to protest. What a miracle it was to have found it!

"That will teach me a lesson," said Ralph, as he helped Linda gather up the lunch. "I'm going to be more careful now. I've put the necklace in my most inside pocket!"

"And I'm not going in for any more acrobatics for a while," added Linda.

They climbed into the cockpit, and started the motor without wasting any more time. Half an hour later they made a graceful landing at Green Falls' Airport, for a group of a hundred spectators to witness and admire.