tom swift sent his wonderful little craft upward on a gentle slant. higher and higher it rose above the ground. now it topped the trees; now it was well over them.

on the earth below stood mr. swift, mr. jackson, eradicate and mrs. baggert. they were the only witnesses of the trial flight, and as the aged inventor saw his son's latest design in aeroplanes circling in the air he gave a cheer of delight. it was too feeble for tom to hear, but the lad, glancing down, saw his father waving his hand to him.

"dear old dad!" thought tom, waving in return. "i hope he's well enough to see me win the big prize."

tom and mr. damon went skimming easily through the air, at no great speed, to be sure, for the young inventor did not want to put too sudden a strain on his motor.

"this is glorious!" cried the odd gentleman. "i never shall have enough of aeroplaning, tom!"

"nor i, either," added his companion. "but how do you like it? don't you think it's an improvement on my butterfly, mr. damon?"

"it certainly is. you're a wonder, tom! look out! what are you up to?" for the machine had suddenly swerved in a startling manner.

"oh, that's just a new kind of spiral dip i was trying," answered tom. "i couldn't do that with my other machine, for i couldn't turn sharp enough."

"well, don't do it right away again," begged mr. damon, who had turned a little white, and whose breath was coming in gasps, even though he was used to hair-raising stunts in the frail craft of the air.

tom did not take his machine far away, for he did not want to exhibit it to the public yet, and he preferred to remain in the vicinity of his home, in case of any accident. so he circled around, did figures of eight, went up and down on long slants, took sharp turns, and gave the craft a good tryout.

"does it satisfy you?" asked mr. damon, when tom had once more made the spiral dip, but not at high speed.

"in a way, yes," was the answer. "i see a chance for several changes and improvements. of course, i know nothing about the speed yet, and that's something that i'm anxious about, for i built this with the idea of breaking all records, and nothing else. i know, now, that i can construct a craft that will successfully navigate the air; in fact, there are any number of people who can do that; but to construct a monoplane that will beat anything ever before made is a different thing. i don't yet know that i have done it."

"when will you?"

"oh, when i make some changes, get the motor tuned up better, and let her out for all she's worth. i want to do a hundred miles an hour, at least. i'll arrange for a speedy flight in about two weeks more."

"then i think i will stay home," said mr. damon.

"no; i'll need you," insisted tom, laughing. "now watch. i'm going to let her out just a little."

he did, with the result that they skimmed through the air so fast that mr. damon's breath became a mere series of gasps.

"we'll have to wear goggles and mouth protectors when we really go fast!" yelled tom above the noise of the motor, as he slowed down and turned about for home.

"go fast! wasn't that fast?" asked mr. damon.

tom shook his head.

"you wait, and you'll see," he announced.

they made a good landing, and mr. swift hastened up to congratulate his son.

"i knew you could do it, tom!" he cried.

"i couldn't, though, if it hadn't been for that wonderful engine of yours, dad! how do you feel?"

"pretty good. oh! but that's a fine machine, tom!"

"it certainly is," agreed mr. jackson.

"it will be when i have it in better trim," admitted the young inventor modestly.

"by golly!" cried eradicate, who was grinning almost from ear to ear, "i's proud oh yo', massa tom, an' so will mah mule boomerang be, when i tells him. yes, sah, dat's what he will be—proud ob yo', massa tom!"

"thanks, rad."

"well, some folks is satisfied with mighty little under 'em, when they go up in the air, that's my opinion," said mrs. baggert.

"why, wouldn't you ride in this?" asked tom of the buxom housekeeper.

"not if you was to give me ten thousand dollars!" she cried firmly. "oh, dear! i think the potatoes are burning!" and she rushed back into the house.

the next day tom started to work overhauling the humming-bird, and making some changes. he altered the wing tips slightly, and adjusted the motor, until in a thrust test it developed nearly half again as much power as formerly.

"and i'll need it all," declared tom as he thought of the number of contestants that had entered the great race.

for the eagle park meet was to be a large and important one, and the principal "bird-men" of the world were to have a part in it. tom knew that he must do his very best, and he spared no efforts to make his monoplane come up to his ideal, which was a very exacting one.

"we'll have a real speed test to-morrow," tom announced to mr. damon one night. "i'll see what the humming-bird can really do. you'll come, won't you?"

"oh, i suppose so. bless my insurance policy! i might as well take the same chance you do. but if you're going to have such a nerve-racking thing as that on the program, you'd better get to bed early and have plenty of sleep."

"oh, i'm not tired. i think i'll go out this evening."

"where?"

"oh, just around town, to see some of the fellows." but if tom was only going around town merely to see his male friends, why did he dress so carefully, put on a new necktie, and take several looks in the glass before he went out? we think you can guess, and also the girl's name.

the young inventor got in rather late, and after a visit to the aeroplane shed, to see that all was right there, he went to bed, first connecting up the burglar-alarm wires that guarded the doors and windows of the aerodrome.

how long he had been asleep tom did not know, but he was suddenly awakened by hearing the buzzing of the alarm at the head of his bed. at first he took it for the droning and humming of the aeroplane motor, as he had a hazy notion, and a sort of dream, that he was in his craft.

then, with a start, he realized what it was—the burglar alarm.

"some one's in the shed!" he gasped.

out of bed he leaped, drawing on his trousers and coat, and putting on a pair of slippers, with speed worthy of a fireman. he grabbed up a revolver and rushed from his room, pounding on the door of mr. jackson's apartment in passing.

"some one in the shed, after the humming-bird!" shouted tom. "get a gun, and come down!"