However, Jackson did, and stopped whirling the blades, turning about to see what was wanted.

"Why, it's Mr. Damon!" exclaimed Tom, as he caught sight of the excited man. "Hello, what's the matter?" the youth asked, pulling aside one flap of his head-covering so he might hear the answer.

"Tom! Wait a minute! Bless my mouse trap!" exclaimed Mr. Damon, "I want to speak to you!" He was panting from his run across the field. "I just got to your house—saw your father—he said you were going up with Miss Nestor, but—bless my dog biscuit—"

"Can't stop now, Mr. Damon!" answered Tom, with a laugh. "I have only just succeeded, by hard work, in getting Mary to a point where she has consented to take a sky ride. If I stop now she'll back out and I'll never get her in again. See you when I come back," and Tom pulled the covering over his ear once more.

"But, Tom, bless my shoe laces! This is important!"

"So's this!" answered Tom, with a grin. He saw, by the motion of Mr. Damon's lips, what the latter had said.

Around swung the propeller blades. The gasoline vapor in the cylinders was being compressed.

"Contact!" called Tom sharply, as he pressed the switch to give the igniting spark at the proper moment. The mechanic had stepped back out of the way, in case there should be a premature starting of the powerful engine, in which event the blades would have cut him to pieces.

"Wait, Tom! Wait! This is very important! Bless my collar button, Tom Swift, but this is—"

Bang! Bang! Bang!

With a series of explosions, like those of a machine gun, the motor started, and further talk was out of the question. Tom turned on more gas. The propellers became almost invisible blades of light and shadow, and the aeroplane began moving over the grassy field. The mechanic had sprung out of the way, pulling Mr. Damon with him.

"Come back! Come back! Wait a minute, Tom Swift! Bless my pansy blossoms, I want to tell you something!" cried the little man.

But Tom Swift was away and out of hearing. He had started on his sky ride with Mary Nestor.

CHAPTER II

A NEW IDEA

Any one who has taken a flight in an aeroplane or gone up in a balloon, will know exactly how Mary Nestor felt on this, her first sky ride of any distance. For a moment, as she looked over the side of the machine, she had a distinct impression, not that she was going up, but that some one had pulled the earth down from beneath her and, at the same time, given her a shove off into space. Such is the first sensation of going aloft. Then the rush of air all about her, the slightly swaying motion of the craft, and the vibration caused by the motor took her attention. But the sensation of the earth dropping away from beneath her remained with Mary for some time.

This sensation is much greater in a balloon than in an aeroplane, for a balloon, unless there is a strong wind blowing, goes straight up, while an aeroplane ascends on a long slant, and always into the teeth of the wind, to take advantage of its lifting power on the underside of the planes. The reason for this sensation—that of the earth's dropping down, instead of one's feeling, what really happens, that one is ascending—is because there are no objects by which comparison can be made. If one starts off on the earth's surface at slow, or at great speed, one passes stationary objects—houses, posts, trees, and the like—and judges the speed by the rapidity with which these are left behind.

Going up is unlike this. There is nothing to pass. One simply cleaves the air, and only as it rushes past can one be sure of movement. And as the air is void of color and form, there is no sensation of passing anything.

So Mary Nestor, as she shot into the air with Tom Swift, had a sensation as though the earth were dropping from beneath her. For a moment she felt as though she were in some vast void—floating in space—and she had a great fear. Then she calmed herself. She looked at Tom sitting in front of her. Of course, all she could see was his back, but it looked to be a very sturdy back, indeed, and he sat there in the aircraft as calmly as though in a chair on the ground. Then Mary took courage, and ceased to grasp the sides of the cockpit with a grip that stiffened all her muscles. She was beginning to "find herself."

On and on, and up and up, went Mary and Tom, in this the girl's first big sky ride. The earth below seemed farther and farther away. The wide, green fields became little emerald squares, and the houses like those in a toy Noah's ark.

Down below, Mr. Wakefield Damon, who had hurried over from his home in Waterfield to see Tom Swift, gazed aloft at the fast disappearing aeroplane and its passengers.

"Bless my coal bin!" cried the eccentric man, "but Tom is in a hurry this morning. Too bad he couldn't have stopped and spoken to me. It might have been greatly to his advantage. But I suppose I shall have to wait."

"You want to see Master?" asked a voice behind Mr. Damon, and, turning, he beheld a veritable giant.

"Yes, Koku, I did," Mr. Damon answered, and he did not appear at all surprised at the sight of the towering form beside him. "I wanted to see Tom most particularly. But I shall have to wait. I'll go in and talk to Mr. Swift."

"Yaas, an' I go talk to Radicate," said the giant. "Him diggin' up ground where Master told me to make garden. Radicate not strong enough for dat!"

"Huh! there's trouble as soon as those two get to disputing," mused Mr. Damon, as he went toward the house.

Meanwhile, Mary was beginning to enjoy herself. The sensation of moving rapidly through the air in a machine as skillfully guided as was the one piloted by Tom Swift was delightful. Up and up they went, and then suddenly Mary felt a lurch, and the plane, which was now about a thousand feet high, seemed to slip to one side.

Mary screamed, and began reaching for the buckle of the safety belt that fastened her to her seat. She saw that something unusual had occurred, for Tom was working frantically at the mechanism in front of him.

But, in spite of this, he seemed aware that Mary was in danger, not so much, perhaps, from what might happen to the machine, as what she might do in her terror.

"Oh! Oh!" cried the girl, and Tom heard her above the terrific noise of the motor, for she was speaking with her lips close to the tube that served as a sort of inter-communicating telephone for the craft. "Oh, we are falling! I'm going to jump!"

"Sit still! Sit still for your life!" cried Tom Swift. "I'll save you all right! Only sit still! Don't jump!"

Mary, her red cheeks white, sank back, and the young inventor redoubled his efforts at the controls and other mechanisms.

And that Tom was perfectly qualified to make a safe landing, even with engine trouble, Mary Nestor well knew. Those of you who have read the previous books of this series know it also, but, for the benefit of my new readers, I shall state that this was by no means Tom's first ride in an aeroplane.

He had operated and built gasoline engines ever since he was about sixteen years old. As related in the initial volume of this series, entitled, "Tom Swift and His Motorcycle," he became possessed of this machine after it had started to climb a tree with Mr. Damon on board. After that experience the eccentric man—blessing everything he could think of—had no liking for the speedy motorcycle and sold it to Tom at a low price.

That was the beginning of a friendship between the two, and also started Tom on his career as an inventor and a possessor of many gasoline craft. For he was not content with merely riding the repaired motorcycle. He made improvements on it.

Tom lived with his father in the town of Shopton, their home being looked after, since the death of Mrs. Swift, by Mrs. Baggert. Mr. Wakefield Damon lived in the neighboring town of Waterfield, and spent much