pausing only long enough to lay aside the pens they had been using to sign the strange agreement, mr. swift and his friends rushed from the private office of the aged inventor where the talk had been going on.

silence had settled over the great swift plant following that booming explosion. but the silence was quickly broken by voices calling:

“fire! fire! fire!”

“bless my insurance policy, something has happened!” gasped mr. damon.

this was so obvious that no one took the trouble to agree with him.

“i hope nothing has happened to tom!” exclaimed mr. swift.

as the four rushed out they were met by eradicate, an old colored man, a sort of family retainer, who was limping along, trying to forget his rheumatism long enough to keep pace with a veritable giant of a man who, with eradicate, was rushing to tell mr. swift the news.

“master’s shop—him go boom!” roared koku, the giant whom tom had captured during one of his strange trips.

“i seen it same as he did!” cried eradicate in his quavering cracked voice. “massa tom’s office done cotch fire!” he added.

“that’s bad!” mr. swift murmured, as he looked toward the part of the works where his son had his own private place for experiments and tests. a pall of smoke hung over it.

while tom’s father and his friends are rushing to do what they can to rescue the young inventor, something about the hero of this story will be told to new readers of this series.

tom swift lived with his father in their beautiful home in shopton, a town in one of our eastern states. tom’s mother had been dead some years, and mrs. baggert was the housekeeper, and a veritable second mother to the young inventor.

for tom was an inventor, like his father, and in the first volume of this series, entitled “tom swift and his motorcycle,” it is related how he bought mr. damon’s smashed machine, improved it, and turned it into one of the speediest things on the road.

tom had many adventures while doing this, as he had while in his motor boat, his sky racer and other machines by which he ate up time and distance as set forth in the various volumes. it was on one of tom’s journeys to unknown lands in a machine of the air that he had brought back koku, one of a race of giants, and since then the big fellow had faithfully served tom swift.

just before the present tale opens, tom, as related in the volume just preceding this, entitled “tom swift and his airline express,” had perfected an aeroplane that could pick up a coach, something like a pullman car, and bear it quickly through space. tom established an airline service across the united states, dividing the journey into several laps, picking up different coaches in chicago, denver, and san francisco.

he succeeded after battling with unscrupulous men who sought to hamper his efforts, and he also succeeded against a financial handicap. when almost doomed to failure, however, tom saved a millionaire, jason jacks, from death in a runaway accident, and out of gratitude mr. jacks loaned tom the money to complete and perfect his airline express.

the odd machine, an airship with a detachable car, met with favor, and from the proceeds of it tom and his father gained large sums. then, running true to form, the young inventor looked for a new world to conquer and turned his attention to a machine he hoped would move rapidly over the land, like a racing automobile, in the air, like an aeroplane, and on the water, like a motor boat.

tom had practically completed his plans, and work on the new apparatus was well under way when the visit of mr. burch and mr. trace occurred, resulting in mr. swift’s rather rash wager.

“i guess i’m likely to lose before tom even has a chance to try,” mused mr. swift as he hurried on toward his son’s private workshop. “if his place is blown up, he may be blown up with it!”

a pall of smoke hung over that part of the works, and it was impossible to see what really had taken place. men were running from other parts of the plant, and the fire alarm was clanging.

tom and his father had mapped out a plan for their own private fire company, since the city engine house in shopton was too far away to be depended on and the swift plant covered a large space of ground. in this plant many machines, not all of tom’s invention or his father’s, were turned out and scores of men were employed.

many of these, realizing the danger as soon as they heard the explosion and listened to the clanging of the fire bell, realized what portended and rushed to their stations. some hurried toward tom’s own particular part of the shop with chemical apparatus, others dragged lines of hose into which the water would soon be turned.

“i hope this is nothing serious,” voiced mr. trace.

“bless my spectacles, it looks bad enough!” fairly shouted mr. damon, pointing to the thick pall of black smoke. “the whole place is gone, i guess!”

however, it was not quite so serious as that, and a moment later, when a puff of wind blew aside the dark vapor, it was seen that tom’s small, private experimental building was standing intact. smoke was pouring from several windows, however, and the shattered glass told its own story. but the smoke was lessening, and this seemed to indicate that the fire was not increasing.

as several of the workmen, bearing portable chemical extinguishers, hurried into the building, mr. damon pointed to a plot of grass beneath one of the windows that, mr. swift well knew, was the place where tom had his desk.

“there’s your boy, now!” said the odd character.

mr. swift caught his breath sharply, for he beheld the prostrate form of tom stretched motionless on the sod.

“that’s bad!” murmured mr. burch softly, and he had it in mind to tear up the wager agreement as soon as possible.

“ho, massa tom!” yelled eradicate in his high-pitched voice. “i save yo’!”

but koku also had a desire to be of service to the master who had been so kind to him, and he likewise pressed forward.

there was a look of pain, grief, and anxiety on the face of mr. swift, and his friends were about to murmur some words of sympathy, for it looked as if tom had been killed, when suddenly that young man stirred, put his hand to his head in a dazed fashion, and then sat up.

“glory be!” shouted eradicate. “he am alive!”

there was no doubt of it. tom swift was not only alive, but he did not seem to be hurt. there were black marks on his hands and face and his clothing was torn, also he was mud-stained where he had fallen into a soft spot on the turf. but he seemed not to be crippled or otherwise seriously injured.

his first glance, after he had looked toward his father and the advancing friends, was to his shop, and when he saw smoke pouring from several windows he leaped up with a cry of alarm.

but a moment later garret jackson, the shop manager, who had been among the first to enter the building, came running out to call:

“fire’s out! not much damage done!”

“thank goodness for that!” murmured mr. burch.

“what happened, tom?” asked mr. damon, with the freedom of an old friend. “sounded as if the place went up.”

“it pretty nearly did,” answered the young inventor, looking at his smudged hands and then wiping his face, on one cheek of which appeared a small trickle of blood. “have you got the fire under control?” he asked mr. jackson.

“yes,” was the answer. “don’t turn on the water!” he shouted as those in charge of a hose line were about to give a signal. “the chemicals are all we needed. the blaze didn’t amount to much.”

“i’m glad of that!” tom was heard to say.

“are you sure you’re all right, my boy?” asked his father.

“positive!” was the quick answer. “sound in wind and limb!” and tom jumped about and executed a few side steps to show that he had not suffered. “i was mixing some chemicals,” he added, “when something went wrong and i saw a smoulder of fire that i knew would turn into an explosion in a few seconds more. so i stood not on the order of my going, but jumped out of the window instead of running to the door.”

“we were wondering why you were lying on that grass plot,” said mr. damon.

“i landed there when i jumped,” explained tom. “and i wasn’t sure but what some of my clothing had caught fire, so i rolled over and lay on my face to protect myself. i couldn’t get up right away—sort of stunned i guess.”

“what were you working on, tom—that new triple traveler?” asked his father, giving the name temporarily assigned to the strange machine that tom hoped would go on land, in the air and in the water.

“well, not directly on that,” said the young inventor as he walked toward his shop to ascertain the extent of the damage. “yet it had to do with it. i was experimenting on a mixture to make gasoline more explosive. not like ethyl gas, though,” he added, “for i want mine to be more powerful but not dangerous.”

“not dangerous!” exclaimed mr. damon. “bless my accident policy, don’t you call a fire, an explosion, and having to jump through a window dangerous enough, tom swift?”

“yes. but i haven’t got my new gasoline mixture perfected yet,” was the answer. “when i do there won’t be any fires or explosions. why did you think i might be working on the triple traveler, dad?” he asked his father.

by this time the fire in the young inventor’s private building was practically out and most of the smoke had blown away. tom and his father and friends entered, and tom pointed to the table where he had been working. some shattered retorts and glass tubes testified as to the explosion’s power. tom had been slightly cut by flying glass, but that was the extent of his injuries.

“well, i had the triple traveler in mind, tom,” said mr. swift, “because, just before you tried to blow yourself up, my friends and i were talking about round-the-world travel. and i guess i sort of made a foolish boast, tom.”

“what was that, dad?”

“why, i said, tom, that you could circle the globe in twenty days actual time—nothing taken out for stops or anything like that. in twenty days flat, tom.”

“well, i guess maybe it can be done when i get my new machine perfected,” the young inventor said, calmly enough.

“it’s got to be done, tom, unless you want me to lose twenty thousand dollars!” said his father.

“twenty thousand dollars! what do you mean?”

“he wagered us ten thousand dollars apiece,” said mr. burch, indicating his friend, “that you, tom swift, could circle the globe in twenty days. we say it can’t be done!”

for a moment tom swift did not answer. his eyes roved to the wall of his office where a world map hung. quickly tom’s eyes glanced along the fortieth parallel of latitude, the most logical course to follow on a race of this sort.

“it can be done,” said tom quietly. “you may take on those bets, dad! i’ll see that you win!” and there was a determined air about him. “i’ll circle the world in twenty days!” promised tom.

“bless my alarm clock, that’s the stuff!” cried mr. damon.

a moment later a girl’s voice out in the plant yard was heard excitedly asking for tom swift.