rapidly the small plane settled in the mud and water. it was down almost to the edge of the cockpit, and tom was about to advise mary to climb out and up on the upper surface of the wings, which he, likewise was going to do, when shouts over to the left attracted the attention of the two.

a couple of men—automobile mechanics to judge by their grease-soiled garments—stood on the edge of the bog, waving their hands.

“hold fast!” the taller one urged. “we’ll get you in a minute!”

“you can’t come out here!” tom shouted back. “it’s a regular quicksand. you’ll get in yourselves!”

“there’s some sort of a boat here,” said the other man. “we’re coming out in that!”

“a boat! then they’ll save us!” gasped mary.

“maybe,” returned tom grimly. he did not understand how a boat could be propelled through that bog which was more like thick, slimy mud than it was water.

the two men disappeared behind a screen of bushes, and mary cried:

“oh, they are leaving us!”

but the reassuring shout came back:

“we’ll be there with the boat in a minute!”

by this time the thick, muddy water (quicksand in solution it was) began seeping over the edge of the cockpit. tom was helping mary to climb up to a dry place, back on the fuselage of the machine, when out of the underbrush the two men emerged, pushing, by means of poles, a low, broad, flat-bottomed punt, which was so broad of beam that it did not sink in the swamp.

“we’ll have you off in a minute!” called the shorter of the two men encouragingly.

by dint of hard pushing they worked the punt to the side of the stranded and bogged aeroplane, and tom and mary lost little time in getting into the safer, if less picturesque, craft.

“will it float with all four of us in it?” tom asked anxiously.

“i guess so,” the tall stranger said. “but it will be slow work poling back to solid ground.”

“sorry we can’t save your bus, mister,” remarked the other.

“don’t worry about the plane,” was tom’s answer. “there are more where that came from. and i may be able to save it at that.”

“it would take a tank to yank that bus out,” said the short man.

“what do you know about tanks?” asked tom, as he took up a pole from the bottom of the punt and helped the two rescuers push the craft toward the solid point of land whence the welcome hails had come.

“i used to manicure one on the other side when we had the big fuss,” was the answer, and tom knew the man had been in one of the ponderous tank machines of the world war.

“i hate to leave that bus,” sighed the tall man, with a look back at the now almost submerged plane. “she’s pretty, but you had some trouble, didn’t you?” he asked. “sounded to me like your motor died on you.”

“it did,” admitted tom. “and i couldn’t straighten out.”

“she was nose diving when my buddy and me saw you as we were riding along in our machine,” went on the tall man.

“nose diving is right,” conceded tom. “but i got her straightened out just in time.”

“but not enough to zoom up,” went on the other, and tom was sure the man knew whereof he spoke.

“you’ve run a bus?” asked tom.

“in france,” was the sufficient answer.

by this time the punt had been poled through the mud, water, and quicksand of the cranberry bog far enough so that all danger was past. it was shoved against the point of land on which the two men had run out as they leaped from their auto, which they said they had left back on the highway.

“well, i guess you’ll be all right now,” remarked the tall man as tom and mary got out of the punt.

“yes, thanks to you,” said the young inventor.

“if we can drop you anywhere in our flivver,” went on the short man, “we’ll do it.”

“if you can take us to the swift plant,” said tom, “it will be a great accommodation.”

“we’ll do that,” said the short man, as his companion made the punt fast to a stump. “that tom swift is the big inventor, isn’t he! do you know him?”

“slightly,” was the answer, with a smile.

“this is tom swift!” exclaimed mary, unable to resist the opportunity. she indicated tom.

“you are?” gasped the short man.

“gee!” exclaimed his tall companion.

“i happen to be,” replied tom. “and if you will leave us at my plant and come in so that i can thank you properly for what you did——”

“aw, forget it!” snapped out the short man. “we don’t want any thanks. you’d do the same, wouldn’t you?”

“of course,” said tom. “but——”

“forget it!” said the other again.

“at least tell me who you are,” begged tom, as the two led the way to where they had left their small touring car.

“i’m joe hartman,” said the tall man who had admitted he was an aviator in the world war.

“and when i hear anybody yell for bill brinkley then i come and get my chow!” added the short chap whimsically.

“this is my friend, miss mary nestor,” introduced tom, and the girl held out a hand each to the two mechanics.

“all oil and grease!” apologized brinkley, putting his hand behind his back. “we work in a garage at waterford,” he went on in explanation.

“and we’ll gum you all up if we shake hands!” added joe hartman bashfully.

“as if i cared!” exclaimed mary, and she insisted on grasping their oil-begrimed palms in a warm pressure. “i want to thank you, too,” she said as she told where she lived, begging the two to call and see her father and mother.

“if you fellows work in waterford, maybe you know mr. wakefield damon?” tom added.

“guess not,” admitted the short man, while his companion shook his head in negation. “we haven’t worked there very long,” he went on. “just now we had to deliver a repaired car in shopton and we two went together. i drove this flivver,” he added with a kick at one of the tires, “so i could bring joe back.”

“well, it’s a good thing you happened to be where you were,” said tom. “and i wish you’d come and see me some time,” he added as the little auto was headed for his plant.

“maybe we will,” was all the two would promise when, a little later, they let tom and mary out at the office entrance and then drove on.

as the accident to the plane had happened several miles from tom’s plant, neither his father, mr. damon, nor the two wagering friends, medwell trace and thornton burch, were aware of it. not until tom and mary came in, somewhat spattered by mud, and told of their experience was anything known of it.

tom sent mary home in an automobile and dispatched some of his workmen with a big truck and long ropes to see if it was possible to get the little plane out of the swamp.

“and now,” said tom, as he finished washing off some of the grime, “i’m going to get seriously to work and help dad win that twenty thousand dollars.”

tom swift had made a start on his new machine some time before. he had conceived the idea of a craft that was at once an automobile, a motor boat, and an aeroplane, and though his father had at first been doubtful and some of the mechanics who worked on it openly skeptical, tom had persisted and now the craft was well on in the process of manufacture.

a model had been made, and though at first it would not work, tom had kept improving it until it was perfect. the only thing that disappointed the young inventor was that it was not speedy enough, and he was looking for fast performances, not only in the air but on land and water.

“i’ve got to use a more powerful gasoline,” he decided and he was experimenting on this fluid when the explosion came. luckily, little damage was done and three days after the fire tom’s office had been repaired and he was hard at work again.

“what are you going to call it, tom?” asked ned newton, the young former bank cashier who was a close friend of the young inventor and, of late, treasurer and one of the managing officials of the swift company. ned was in tom’s private workshop looking at the strange device.

“well, i did think of calling it monarch,” was the answer. “the air monarch might not be such a bad name, if it does what i think it will do.”

“when will you know?” ned asked.

“in a few weeks. i’m going to rush work on it, now that dad has made his wagers. i’ve got to help him win that twenty thousand dollars.”

“do you think you can?” asked ned.

“i’m going to!” declared tom, with conviction. “take a look at the air monarch, ned, and see what you think of her as far as i’ve gone.”

“looks pretty good,” admitted the young treasurer. “what’s that for?” and he pointed to a small door in the rear of the machine, a door under the tail rudder.

“that’s where the propeller is concealed,” was tom’s answer. “look and you’ll see how it works!”

he pulled a lever, the door slid back, and in a tunnel-shaped compartment was a large, three-bladed, bronze propeller.

“that’s for use when running on the water,” the inventor explained.

“how does it run on land?” inquired ned. “like an automobile?”

“not exactly,” tom said. “the same propeller that sends the craft through the air sends it along on the ground. just as an aeroplane taxies across the field before mounting, you know. by keeping the tail rudder depressed i prevent the machine from rising, and it moves over the ground, though of course not as fast as in the air.”

“there is no direct drive on these wheels then?” asked ned, pointing to four strong wheels on which the machine rested and on which it would land after making a flight.

“oh, yes, i can drive the car on the ground by gearing the motor directly to the wheels,” said tom. “but i can’t get much speed that way, though i do get a lot of power. and in front here——”

but tom suddenly stopped his explanations and looked toward the door of his private shop. the knob was turning in a stealthy manner.