"well, did i make it? make any kind of a record?" asked tom eagerly, as he brought the trim little craft to a stop, after it had rolled along the ground on the bicycle wheels.

"what do you think you did?" asked mr. jackson, who had been busy figuring on a slip of paper.

"did i get her up to ninety miles an hour?" inquired tom eagerly. "if i did, i know when the motor wears down a bit smoother that i can make her hit a hundred in the race, easily. did i touch ninety, mr. jackson?"

"better than that, tom! better than that!" cried his father.

"yes," joined in mr. jackson. "allowing for the difference in our watches, tom, your father and i figure that you did the course at the rate of one hundred and twelve miles an hour!"

"one hundred and twelve!" gasped the young inventor, hardly able to believe it.

"i made it a hundred and fifteen," said mr. swift, who was almost as pleased as was his son, "and mr. jackson made it one hundred and eleven; so we split the difference, so to speak. you certainly have a sky racer, tom, my boy!"

"and i'll need it, too, dad, if i'm to compete with andy foger, who may have a machine almost like mine."

"but i thought you were going to object to him if he has," said mr. damon, who had hardly recovered from the speedy flight through space.

"well, i was just providing for a contingency, in case my protest was overruled," remarked tom. "but i'm glad the humming-bird did so well on her first trial. i know she'll do better the more i run her. now we'll get her back in her 'nest,' and i'll look her over, when she cools down, and see if anything has worked loose."

but the trim little craft needed only slight adjustments after her tryout, for tom had built her to stand up under a terrific strain.

"we'll soon be in shape for the big race," he announced, "and when i bring home that ten thousand dollars i'm going to abandon this sky-scraping business, except for occasional trips."

"what will you do to occupy your mind?" asked mr. damon.

"oh, i'm going to travel," announced tom. "then there's my new electric rifle, which i have not perfected yet. i'll work on that after i win the big race."

for several days after the first real trial of his sky racer tom was busy going over the humming-bird, making slight changes here and there. he was the sort of a lad who was satisfied with nothing short of the best, and though neither his father nor mr. jackson could see where there was room for improvement, tom was so exacting that he sat up for several nights to perfect such little details as a better grip for the steering-lever, a quicker way of making the automatic equilibriumizer take its position, or an improved transmitter for the wireless apparatus.

that was a part of his monoplane of which tom was justly proud, for though many aeroplanes to-day are equipped with the sending device, few can receive wireless messages in mid-air. but tom had seen the advantage of this while making a trip in the ill-fated red cloud to the cave of the diamond makers, and he determined to have his new craft thus provided against emergencies. the wireless outfit of the humming-bird was a marvel of compactness.

thus the days passed, with tom very busy; so busy, in fact, that he hardly had time to call on miss nestor. as for andy foger, he heard no more from him, and the bully was not seen around shopton. tom concluded that he was at his uncle's place, working on his racing craft.

the young inventor sent a formal protest to the aviation committee, to be used in the event of andy entering a craft which infringed on the humming-bird, and received word from mr. sharp that the interests of the young inventor would be protected. this satisfied tom.

still, at times, he could not help wondering how the first plans had so mysteriously disappeared, and he would have given a good deal to know just how andy got possession of them, and how he knew enough to use them.

"he, or some one whom he hired, must have gotten into our house mighty quickly that day," mused tom, "and then skipped out while dad fell into a little doze. it was a mighty queer thing, but it's lucky it was no worse."

the time was approaching for the big aviation meet. tom's craft was in readiness, and had been given several other trials, developing more speed each time. additional locks were put on the doors of the shed, and more burglar-alarm wires were strung, so that it was almost a physical impossibility to get into the humming-bird's "nest" without arousing some one in the swift household.

"and if they do, i guess we'll be ready for them," said tom grimly. he had been unable to find out who it was that had attempted once before to damage the monoplane, but he suspected it was the ill-favored man who was working with andy.

as for mr. swift, at times he seemed quite well, and again he required the services of a physician.

"you will have to be very careful of your father, tom," said dr. gladby. "any sudden shock or excitement may aggravate his malady, and in that case a serious operation will be necessary."

"oh, we'll take good care of him," said the lad; but he could not help worrying, though he tried not to let his father see the strain which he was under.

it was some days after this, and lacking about a week until the meet was to open, when a peculiar thing happened. tom had given his humming-bird a tryout one day, and had then begun to make arrangements for taking it apart and shipping it to eagle park. for he would not fly to the meet in it, for fear of some accident. so big cases had been provided.

"i'll take it apart in the morning," decided tom, as he went to his room, after seeing to the burglar alarm, "and ship her off. then mr. damon and i will go there, set her up, and get ready to win the race."

tom had opened all the windows in his room, for it was very warm. in fact it was so warm that sleep was almost out of the question, and he got up to sit near the windows in the hope of feeling a breeze.

there it was more comfortable, and he was just dozing off, and beginning to think of getting back into bed, when he was aware of a peculiar sound in the air overhead.

"i wonder if that's a heavy wind starting up?" he mused. "good luck, if it is! we need it." the noise increased, sounding more and more like wind, but tom, looking out into the night, saw the leaves of the trees barely moving.

"if that's a breeze, it's taking its own time getting here," he went on.

the sound came nearer, and then tom knew that it was not the noise of the wind in the trees. it was more like a roaring and rumbling.

"can it be distant thunder?" tom asked himself. "there is no sign of a storm." once more he looked from the window. the night was calm and clear—the trees as still as if they were painted.

the sound was even more plain now, and tom, who had sharp ears, at once decided that it was just over the house—directly overhead. an instant later he knew what it was.

"the motor of an aeroplane, or a dirigible balloon!" he exclaimed. "some one is flying overhead!"

for an instant he feared lest the shed had been broken into, and his humming-bird taken, but a glance toward the place seemed to show that it was all right.

then tom hastily made his way to where a flight of stairs led to a little enclosed observatory on the roof.

"i'm going to see what sort of a craft it is making that noise," he said.

as he opened the trap door, and stepped out into the little observatory the sound was so plain as to startle him. he looked up quickly, and, directly overhead he saw a curious sight.

for, flying so low as to almost brush the lightning rod on the chimney of the swift home, was a small aeroplane, and, as tom looked up, he saw in a light that gleamed from it, two figures looking down on him.