was that the prospective excitement of the moment caused the blood to surge into her cheeks. Have it as you will.

"Come, Mary! you're not going to back out the last minute, are you?" asked Tom Swift. "Everything is all right. I've made a trial flight, and you've seen me come down as safely as a bird. You promised to go up with me. I won't go very high if you don't like it, but my experience has been that, once you're off the ground, it doesn't make any difference how high you go. You'll find it very fascinating. So skip along to the house, and Mrs. Baggert will help you get into your togs."

"Shall I have to wear all those things—such as you have on?" asked Mary, blushing again.

"Well, you'll be more comfortable in a fur-lined leather suit," asserted Tom. "And if it does make you look like an Eskimo, why I'm sure it will be very becoming. Not that you don't look nice now," he hastened to assure Miss Nestor, "but an aviation suit will be very—well, fetching, I should say."

"If I could be sure it would 'fetch' me back safe, Tom—"

"That'll do! That'll do!" laughed the young aviator. "One joke like that is enough in a morning. It was pretty good, though. Now go on in and tog up."

"You're sure it's safe, Tom?"

"Positive! Trot along now. I want to fix a wire and—"

"Oh, is anything broken?" and the girl, who had started away from the aeroplane, turned back again.

"No, not broken. It's only a little auxiliary dingus I put on to make it easier to read the barograph, but I think I'll go back to the old system. Nothing to do with flying at all, except to tell how high up one is."

"That's just what I don't care to know, Tom," said Mary Nestor, with a smile. "If I could imagine I was sailing along only about ten feet in the air I wouldn't mind so much."

"Flying at that height would be the worst sort of danger. You leave it to me, Mary. I won't take you up above the clouds on this sky ride; though, later, I'm sure you'll want to try that. This is only a little flight. You've been promising long enough to take a trip with me, and now I believe you're trying to back out."

"No, really I'm not, Tom! Only, at the last minute, the machine looks so small and frail, and the sky is so—big—"

She glanced up and seemed to shiver just a trifle.

"Don't be thinking of those things, Mary!" laughed Tom Swift. "Trot along and get ready. The motor never worked better, and we may break a few speed records this morning. No traffic cops to stop us, either, as there might be if we were in an auto."

"There you go, Mary!" exclaimed Tom, as if struck with a new thought. "You've ridden in an auto with me many a time, and you never were a bit afraid, though we were in more danger than we'll be this morning."

"Danger, Tom, in an auto? How?"

"Why, danger of a wheel collapsing as we were going full speed; or the steering knuckle breaking and sending us into a tree; danger of running into a stone wall or a ditch; danger of some one running into us, or of us running into some one else. There isn't one of these dangers on a sky ride."

"No," said Mary slowly. "But there's the danger of falling."

"One against twenty. That's the safety margin. And, if we do fall, it will be like landing in a feather bed! There, don't wait any longer. Go and get ready."

Mary sighed, and then, seeming to summon her nerve to her aid, she smiled brightly, waved her hand to Tom, and hastened toward his home, where Mrs. Baggert the matronly housekeeper, was waiting to help the girl attire herself in a flying-suit of leather.

Mary Nestor, who had a very warm place in the heart of Tom Swift, had, as he stated, some time since promised to take a trip in the air with the young inventor. But she had kept putting it off, for one reason or another, until Tom began to despair of ever getting her to accompany him. To-day, however, when she had called to inquire about his father, who had been slightly ill, Tom had, after the social visit, insisted on the promise being kept.

He had his mechanic get out one of the safest, though a speedy, double machine, and, with Mary to watch, Tom had taken a trial flight, just to show her how easy it was. It was not the first time she had seen him take to the air, but now she watched with different emotions, for she was vitally interested.

Tom had sailed down from aloft, making a landing in the aviation field he had constructed near his home, and then he had insisted that Mary should keep her promise to take a sky ride with him.

"Don't be too long now!" called Tom to the girl, as she hurried toward the house. "Never mind about your hair, or whether your hat's on straight. You're going to wear a cap, anyhow, and tuck your hair up under that. It's hot down here, but it will be cold up above; so tell Mrs. Baggert to see that you're warmly dressed."

"All right," and gaily she waved her hand to him. Now that she had made her decision, and was really going up, she was not half so frightened as she had been in the contemplation of it.

As Tom climbed out of the machine, to give it a careful inspection, though he was certain there was nothing wrong, an aged colored man shuffled toward him.

"Yo'—yo'll be mighty careful ob Miss Nestor now, won't yo', Massa Tom?" asked the man.

"Of course I will, Eradicate," was the young inventor's answer.

"Case we ain't got many laik her no mo', an' dat's de truf, Massa Tom," went on the old man. "So be mighty careful laik!"

"That's what I will, Rad! And, while I'm up in the air, don't you and Koku have any trouble."

"Ho! Trouble wif dat onery no-'count giant! I guess not!" and the colored man limped off, highly indignant.

Satisfied, from an inspection of his machine, that it was as nearly mechanically perfect as it was possible to be, Tom Swift finished his trip around it and stood near the big propeller, waiting for Mary Nestor to reappear. Presently she did so, and Tom gaily waved his hand to her.

"You're a picture!" he cried, as he saw how particularly "fetching" she looked in the aviator's costume which was like his own. Because of the danger of entanglement, Miss Nestor had doffed her skirts, and wore the costume of all aviators—men and women.

"I wish I had my camera!" cried Tom. "You look—stunning!"

"I hope that isn't any comment on how I'm going to feel if we have to make a—forced landing, I believe you call it," she retorted.

"Oh, I'll take care of that!" exclaimed Tom. "Now up you go, and we'll start," and he helped her to climb into the padded seat of the cockpit, behind where he was to sit.

"Oh, Tom! Don't be in such a hurry!" expostulated Mary. "Let me get my breath!"

"No!" laughed the young inventor. "If I did you might back out. Get in, fasten the strap around you and sit still. That's all you have to do. Don't be afraid, I'll be very careful. And don't try to yell at me to go slower or lower once we're up in the air.

"Why not?" Mary wanted to know, as she settled herself in her seat.

"Because I can't very well hear you, or talk to you. The motor makes so much noise, you know. We can do a little talking through this speaking tube," and he indicated one, "but it isn't very satisfactory. So if you have anything to say—"

"In the language of the poets," interrupted Mary, "if I have words to spill, prepare to spill them now. Well, I haven't! Now I'm here, go ahead! I shall probably be too frightened to talk, anyhow."

"Oh, no you won't—after the first little sensation," Tom assured her. "You'll be crazy about it. Come on, Jackson!" he called to the mechanician. "Start the ball rolling!"

Tom was in his place, his goggles and cap well down over his face, and he was adjusting the switch as the mechanic prepared to spin the propellers.

Suddenly a man came running from the Swift house, waving his arms not unlike the blades of an aircraft propeller, he also shouted, but Tom, whose ears were covered with his fur cap, could not hear.