"bless my gizzard!" exclaimed mr. damon, who hardly knew what to do. "we'd better be getting out of here, tom!"

"not much!" exclaimed the young inventor. "i never ran from andy foger yet, and i'm not going to begin now."

he assumed an attitude of defense, and stood calmly awaiting the onslaught of the bully; but andy knew better than to come to a personal argument with tom, and so the red-haired lad halted some paces off. the man, who had followed young foger, also stopped.

"what do you want around here, tom swift?" demanded andy.

"you know very well what i want," said the young inventor, calmly. "i want to know what you did with the aeroplane plans you took from my house."

"i never took any!" declared andy vigorously.

"well, there's no use discussing that," went on tom. "what i came here to find out, and i don't mind telling you, is whether or not you are building a monoplane to compete against me, and building it on a model invented by me; and what's more, andy foger, i intend to find this out, too!"

tom started toward the big shed, which loomed up in the moonlight.

"stand back!" cried andy, getting in tom's way. "i can build any kind of an aeroplane i like, and you can't stop me!"

"we'll see about that," declared the young inventor, as he kept on. "i'm not going to allow my plans to be stolen, and a monoplane made after them, and do nothing about it."

"you keep away!" snarled andy, and he grabbed tom by the shoulder and struck him a blow in the chest. he must have been very much excited, or otherwise he never would have come to hostilities this way with tom, whom he well knew could easily beat him.

the blow, together with the many things he had suffered at andy's hands, was too much for our hero. he drew back his fist, and a moment later andy foger was stretched out on the grass. he lay there for a moment, and then rose up slowly to his knees, his face distorted with rage.

"you—you hit me!" he snarled.

"not until you hit first," said tom calmly.

"bless my punching bag! that's so!" exclaimed mr. damon.

"you'll suffer for this!" whined andy, getting to his feet, but taking care to retreat from tom, who stood ready for him. "i'll get square with you for this! jake, come on, and we'll get our guns!"

andy turned and hurried back toward the shed, followed by the evil-looking man, who had apparently been undecided whether to attack mr. damon or tom. now the bully and his companion were in full retreat.

"we'll get our guns, and then we'll see whether they'll want to stay where they're not wanted!" went on andy, threateningly.

"bless my powderhorn! what had we better do?" asked mr. damon.

"i guess we'd better go back," said tom calmly. "not that i'm afraid of andy. his talk about guns is all bluff; but i don't want to get into any more of a row, and he is just ugly and reckless enough to make trouble. i'm afraid we can't learn what we came to find out, though i'm more convinced than ever that andy is using my plans to make his aeroplane."

"but what can you do?"

"i'll see mr. sharp, and send a protest to the aviation committee. i'll refuse to enter if andy flies in a model of my humming-bird, and i'll try to prevent him from using it after he gets it on the ground. that is all i can do, it seems, lacking positive information. come on, mr. damon. let's get back to our hotel, and we'll start for home in the morning."

"i have a plan," whispered the odd man.

"what is it?" asked tom, narrowly watching for the reappearance of andy and the man.

"i'll stay here until they come, then i'll pretend to run away. they'll chase after me, and get all excited, and you can go up and look in the shed windows. then you can join me later. how's that?"

"too risky. they might fire at you by mistake. no. we'll both go. i've found out more than enough to confirm my suspicions."

they turned out of the lot which contained the shed, and walked toward the road, just as andy and his crony came back.

"huh! you'd better go!" taunted the bully.

tom had a bitter feeling in his heart. it seemed as if he was defeated, and he did not like to retreat before andy.

"you'd better not come back here again, either," went on andy.

tom and mr. damon did not reply, but kept on in silence. they returned to shopton the next day.

"well," remarked tom, when he had gone out to look at his humming-bird, "i know one thing. andy foger may build a machine something like this, but i don't believe he can put in all the improvements i have, and certainly he can't equal that engine; eh, dad?"

"i hope not, tom," replied his father, who seemed to be much improved in health.

"when are you going to try for speed?" asked mr. damon.

"to-morrow, if i can get it tuned up enough," replied tom, "and i think i can. yes, we'll have the great test to-morrow, and then i'll know whether i really have a chance for that ten thousand dollars."

never before had tom been so exacting in his requirements of his air craft as when, the next day, the humming-bird was wheeled out to the flight ground, and gotten ready for the test. the young inventor went over every bolt, brace, stay, guy wire and upright. he examined every square inch of the wings, the tips, planes and rudders. the levers, the steering wheel, the automatic equilibrium attachments and the balancing weights were looked at again and again.

as for the engine, had it been a delicate watch, tom could not have scrutinized each valve, wheel, cam and spur gear more carefully. then the gasoline tank was filled, the magneto was looked after, the oil reservoirs were cleaned out and freshly filled, and finally the lad remarked:

"well, i guess i'm ready. come along, mr. damon."

"am i going with you in the test?"

"surely. i've been counting on you. if you're to be with me in the race, you want to get a sample of what we can do. take your place. mr. jackson, are you ready to time us?"

"all ready, tom."

"and, dad, do you feel well enough to check back mr. jackson's results? i don't want any errors."

"oh, yes, tom. i can do it."

"very well, then. now this is my plan. i'm going to mount upward on an easy slant, and put her through a few stunts first, to warm up, and see that everything is all right. then, when i give the signal, by dropping this small white ball, that means i'm ready for you to start to time me. then i'll begin to try for the record. i'll go about the course in a big ellipse, and—well, we'll see what happens."

while mr. damon was in his seat the young inventor started the propeller, and noted the thrust developed. it was satisfactory, as measured on the scale, and then tom took his place.

"let her go!" he cried to mr. jackson and eradicate, after he had listened to the song of the motor for a moment. the humming-bird flew across the course, and a moment later mounted into the air.

tom quickly took her up to about two thousand feet, and there, finding the conditions to his liking, he began a few evolutions designed to severely test the craft's stability, and to learn whether the engine was working properly.

"how about it?" asked mr. damon anxiously.

"all right!" shouted tom in his ear, for the motor was making a great racket. "i guess we'll make the trial next time we come around. get ready to drop the signal ball."

tom slowly brought the aeroplane around in a graceful curve. he sighted down, and saw the first tall white pole that marked the beginning of the course.

"drop!" he called to mr. damon.

the white rubber ball went to the earth like a shot. mr. jackson and mr. swift saw it, and started their timing-watches. tom opened the throttle and advanced the spark. the great test was on!

the humming-bird trembled and throbbed with the awful speed of the motor, like a thing alive. she seemed to rush forward as an eagle dropping down from a dizzy height upon some hapless prey.

"faster yet!" murmured tom. "we must go faster yet!"

the motor was warming up. streaks of fire came from it. the exhaust of the explosions was a continuous roar. faster and faster flew the frail craft.

around and around the air course she circled. the wind appeared to be rushing beneath the planes and rudders with the velocity of a hurricane. had it not been for the face protectors they wore, tom and mr. damon could not have breathed. for ten minutes this fearful speed was kept up. then tom, knowing he had run the motor to the limit, slowed it down. next he shut it off completely, and prepared to volplane back to earth. the silence after the terrific racket was almost startling. for a moment neither of the aviators spoke. then mr. damon said:

"do you think you did it, tom?"

"i don't know. we'll soon find out. they'll have the record." and he motioned toward the earth, which they were rapidly nearing.