“what happened? is tom hurt? let me go to him at once!” the voice exclaimed.

a smile came over tom’s face.

“it’s mary nestor,” he murmured, and to the two visitors mr. damon explained in an aside:

“she and tom are engaged.”

“lucky boy!” murmured mr. burch as he caught sight of a pretty girl hurrying into the rather upset office. for the place was upset in spite of the comparatively small damage caused by the explosion and fire.

“oh, tom! are you hurt?” mary cried, hastening toward him, totally oblivious of all the others in the disordered room. “i heard a rumor that your whole plant had burned and i came over as fast as i could.”

“well, mary,” went on the young inventor, with a smile, “i’m glad to say that, for once, rumor got ahead of itself. nothing very much happened. just a few chemicals went off unexpectedly.”

“but you’re cut!” mary gasped, as she saw the blood on tom’s cheek. “oh!”

“just a scratch from a broken test tube,” he explained.

then mr. burch, with a fine sense of what was fitting, said:

“mr. trace, since we have concluded our business here and have made arrangements for separating our friend bart from twenty thousand dollars, we might as well get out and——”

he did not say it, but the inference was obvious that he wanted to leave the two young people alone. tom seemed to sense this for he said:

“just a moment, please. i want to understand a little more about this wager.”

“you’ll understand it better when your dad has to take some of his big profits and hand over twenty thousand to us,” chimed in mr. trace. it was true that the swift company had been very profitable of late, thanks to some of tom’s inventions.

“but still i don’t like the idea of losing twenty thousand, or even ten,” said tom, with a smile. “and i don’t intend to lose it, either, gentlemen!” he concluded.

“i’m glad you are backing me up, tom,” murmured his father. “how soon will the triple traveler be done?”

tom looked at some plans on his desk, glanced at the world map and was about to answer when mary broke in with:

“is this a hold-up?” her smile took any menace from the words.

“it’s just a little bet among three old friends,” said mr. burch, with a chuckle, “and our friend tom is going to be the goat. i mean he is going to lose the race!” he concluded.

“not much i’m not!” cried the young inventor, and when mary looked a bit mystified mr. trace explained:

“we were discussing various means of travel, miss nestor, and the feat of jules verne’s hero in girdling the earth in eighty days. that time has been brought down to about thirty, but tom’s father declared it could be done within twenty days.”

“that suits me!” cried tom. “if you give me time to complete the making of my new machine i’ll prove my father to be right.”

“good boy!” murmured the aged inventor.

“then you will have a part in this wager,” suggested mr. trace.

“that suits me!” went on tom. “let me see—what can i do with my share of twenty thousand dollars?” he asked musingly, and with a smile. but the smile faded when he looked at mary’s face and saw how distressed she was.

“oh, tom,” she murmured, “think how near death you were just now in the explosion! and now you are going to risk your life again in one of your strange machines!”

she bit her lips to keep back her tears, it seemed, and the young inventor, seeing that she was on the verge of a nervous alarm, quickly said:

“don’t worry, mary! there’s no danger at all. wait until you take a look at my new triple traveler. come on out and i’ll show it to you.”

tom did not invite any of the others into that part of the works whither he led mary nestor, and mr. damon and his friends had common sense enough not to intrude where, obviously, they were not wanted. tom did not stop to wash his hands or face of the grime of the explosion, and he only wiped away the blood, which had now almost ceased to flow from the slight cut.

he led the girl into a large building, the doors of which were carefully locked, and when mary’s eyes had become accustomed to the gloom she saw a dim shape of something which seemed to have the elongated body of a boat, beneath which were sturdy wheels and above which were stretched big wings like those on an aeroplane, with two rear propellers.

“this is really only a working model,” tom explained.

“a working model of what?” inquired mary.

“well, the triple traveler is all we call it at present,” tom answered. “as you see——”

“i can’t see anything much!” interrupted mary.

“well you’ll see later,” went on tom. “it’s a secret yet and i have the windows shrouded. that’s also why i keep the doors locked. no telling who of my enemies might try to sneak this new machine away from me. i’ve got to be careful. but when it’s finished it will be one of the best things i have ever made.”

“and are you really going to circle the earth in it, tom?”

“i’m going to try. there’s no question but what i can do it. but whether i can do it inside of twenty days is another question.”

“you don’t mean to say you are going to try to win that foolish bet?”

“i don’t see how i can help myself,” replied tom. “it may have been a bit rash of dad to make it, but, now that he has, i must do all i can to help him win it. i owe it to my own reputation. it isn’t so much a question of the money.”

“oh, dear!” sighed mary.

“what’s the matter?”

“i wish you weren’t always chasing off on these wild trips, tom!”

“i don’t go very often. and they aren’t as wild as the ones i used to take at first—like those to the bottom of the sea, for instance. i haven’t been on any for a long while, either.”

“no! not since last fall when you inaugurated the airline express,” said mary, a bit sarcastically. “and look what a lot of danger you were in!”

“but i came out all right and i made a lot of money,” said tom, defending himself.

“and now you’re going around the world. oh, dear!” and mary sighed dolefully.

tom looked at her sharply. he saw that she was laboring under the reaction of fear after having heard the false report that his plant was blown up.

“look here, mary,” he said, “i’m afraid you’re losing your nerve! that will never do!”

“losing my nerve?”

“yes. i’ll wager right now any flavor of ice-cream you care to name that you don’t dare take an aeroplane ride with me!”

“i’ll take you up!” cried mary, and she smiled. “i’ll show you!” and she tossed her head.

she often accompanied tom on his trips in one of his smaller and less complicated aeroplanes, for tom traveled this way on many occasions, to transact some business or to conduct experiments having to do with other machines.

“then you’ll take a sky trip with me, mary?”

“i surely will. i think it will do me good!”

“i’m sure of it,” said tom, smiling.

they went out of the partially wrecked office, tom giving orders to have it cleaned up and his gasoline experimental apparatus put aside for future use.

tom next gave orders to have one of his speedy double planes run into the flying field while he went to the house to wash and get ready for the trip with mary. then he added his name to the signatures on the bet agreement, and said inside of six months from the present time he would start to circle the globe.

mr. swift, who had somewhat regretted his rash action, was all smiles now, for he had great faith in tom.

“of course twenty thousand dollars won’t break us, tom,” he confided to his son as the latter was putting on his leather flying helmet and getting one ready for mary, together with a leather jacket. “but, at the same time, i’d like to win it.”

“same here, dad,” echoed tom. “and we will, too!”

in a short time the little plane, which would carry only two, was in readiness. the motor was tuned up and tom and mary took their places in the double cockpit, where the girl sat beside her sweetheart. it was a type of plane perfected by tom.

“where to, mary?” asked tom, as he looked over the controls.

“oh, anywhere,” she answered. “i want to get away from everything for a while.”

“then maybe you’d rather go up alone,” suggested the young man.

“i said everything—not everybody,” and mary’s accent made the meaning clear, at which tom laughed.

he turned on more gas, there was a roar from the motor, the plane taxied across the field, and a few seconds later was soaring up toward the blue.

“i suppose you’ll be traveling like this when you start on that—i can’t help saying it—foolish trip around the world, tom,” said mary.

“a lot faster,” was his answer. “you see i’ve got to do twenty-five thousand miles in twenty days. that’s twelve hundred miles a day. counting twelve hours to a day on the average, that’s a hundred miles an hour. but of course there will have to be stops, forced or others, and so practically i’ll have to double that rate and make it two hundred miles or more of flying every hour.”

“can you go that fast, tom?”

“faster, i hope. i just read of a navy seaplane that did two hundred and fifty-six miles an hour. i’m going to better that record if i can. just wait until i get the new triple traveler finished.”

“i hope it doesn’t finish you, tom,” said mary.

he leaned over toward her. by a new muffler attachment on the engine the roar of the exhaust was deadened and it was possible to talk without shouting. love making can never be carried on in shouts, as you know well.

on and on flew tom and mary, the little plane gaining speed and height each minute. they were soon up above the clouds, flying fast.

“you’re a good traveler, mary,” said tom. “how’d you like to come along on the world-circling jaunt?”

“in some ways i’d like it—i could make sure you were safe,” she said with a smile. “but i’m afraid i can’t manage it,” she added, as tom gave her hand a squeeze. to do this he had to release one of the levers he was manipulating, and when he again shifted it there was a peculiar sound.

“what’s that?” cried the girl.

tom swift did not answer, but began frantically manipulating the controls. the plane was acting in a peculiar manner—even mary with her inexperience realized that.

“is anything wrong?” she asked.

“i’m afraid there is,” tom answered with a grim tightening of his jaws. “we seem to be going into a nose dive!”

hardly had he spoken than the plane tilted forward and plunged toward the earth at frightful speed.