"I don't believe they will," Tom assured him. "Garret and Mrs. Baggert will be on guard."

The next few days were pleasant ones for Tom, his father and Ned Newton. They cruised about the lake, went fishing and camped in the woods. Even Mr. Swift spent one night in the tent and said he liked it very much. For a week the three led an ideal existence, going about as they pleased, Ned taking a number of photographs with his new camera. The ARROW proved herself a fine boat, and Tom and Ned, when Mr. Swift did not accompany them, explored the seldom visited parts of Lake Carlopa.

The three had been out one day and were discussing the necessity of returning home soon when Ned spoke.

"I shall hate to give up this life and go to slaving in the bank again," he complained. "I wish I was an inventor."

"Oh, we inventors don't have such an easy time," said Mr. Swift. "You never know when trouble is coming," and he little imagined how near the truth he was.

A little later they were at the hotel dock. When Tom had tied up his boat the three walked up the path to the broad veranda that faced the lake. A boy in uniform met them.

"Some one has just called you on the telephone, Mr. Swift," he reported.

"Some one wants me? Who is it?"

"I think he said his name is Jackson, sir, Garret Jackson, and he says the message is very important."

"Tom, something has happened at home!" exclaimed the inventor as he hurried up the steps. "I'm afraid there's bad news."

Unable to still the fear in his heart, Tom followed his father.



CHAPTER XX

NEWS OF A ROBBERY

With a hand that trembled so he could scarcely hold the receiver of the telephone, Mr. Swift placed it to his ear.

"Hello! Hello!" he cried into the transmitter. "Yes, this is Mr. Swift—yes, Garret. What is it?"

Then came a series of clicks, which Tom and Ned listened to. The inventor spoke again.

"What's that? The same men? Broke in early this evening? Oh, that's too bad! Of course, I'll come at once."

There followed more meaningless clicks, which Tom wished he could translate. His father hung up the receiver, turned to him and exclaimed:

"I've been robbed again!"

"Robbed again! How, dad?"

"By that same rascally gang, Garret thinks. This evening, when he and Mrs. Baggert were in the house the burglar alarm went off. The indicator showed that the electrical shop had been entered, and the engineer hurried there. He saw a light inside and the shadows of persons on the windows. Before he could reach the shop, however, the thieves heard him coming and escaped. Oh, Tom, I should never have come away!"

"But did they take anything, dad? Perhaps Garret frightened them away before they had a chance to steal any of your things. Did you ask him that?"

"I didn't need to. He said he made a hasty exanimation before he called me up, and he is sure a number of my electrical inventions are missing. Some of them are devices I never have had patented, and if I lose them I will have no recovery."

"But just what ones are they? Perhaps we can send out a police alarm to-night."

"Garret couldn't tell that," answered Mr. Swift as he paced to and fro in the hotel office. "He doesn't know all the tools and machinery I had in there. But it is certain that some of my most valuable things have been taken."

"Never mind. Don't worry, dad," and Tom tried to speak soothingly, for he saw that his father was much excited. "We may be able to get them back. How does Garret know the same men who stole the turbine model broke in the shop this evening?"

"He saw them. One was Happy Harry, he is positive. The others he did not know, but he recognized the tramp from our description of him."

"Then we must tell the police at once."

"Yes, Tom, I wish you would telephone. I'll give you a description of the things. No, I can't do that either, for I don't know what was stolen. I must go home at once to find out. It's a good thing the motor-boat is here. Come, let's start at once. What is my bill here?" and the inventor turned to the hotel proprietor, who had come into the office. "I have suffered a severe loss and must leave at once."

"I am very sorry, sir. I'll have it ready for you in a few minutes."

"All right. Tom, is your boat ready for a quick trip?"

"Yes, dad, but I don't like to make it at night with three in. Of course it might be perfectly safe, but there's a risk, and I don't like to take it."

"Don't worry about the risk on my account, Tom. I'm not afraid. I must get home and see of what I have been robbed."

The young inventor was in a quandary. He wanted to do as his father requested and to aid him all he could, yet he knew that an all-night trip in the boat down the lake would be dangerous, not only from the chance of running on an unknown shore or into a hidden rock, but because Mr. Swift was not physically fitted to stand the journey.

"Come, Tom," exclaimed the aged inventor impatiently, "we must start at once!"

"Won't morning do as well, dad?"

"No, I must start now. I could not sleep worrying over what has happened. We will start—"

At that instant there came a low, rumbling peal of thunder. Mr. Swift started and peered from a window. There came a flash of lightning and another vibrant report from the storm-charged clouds.

"There is your bill, Mr. Swift," remarked the proprietor, coming up, "but I would not advise you to start to-night. There is a bad storm in the west, and it will reach here in a few minutes. Storms on Lake Carlopa, especially at this open and exposed end, are not to be despised, I assure you."

"But I must get home!" insisted Tom's father.

The lace curtain over the window blew almost straight out with a sudden breeze, and a flash of lightning so bright that it reflected even in the room where the incandescent electrics were glowing made several others jump. Then came a mighty crash, and with that the flood-gates of the storm were opened, and the rain came down in torrents. Tom actually breathed a sigh of relief. The problem was solved for him. It would be impossible to start to-night, and he was glad of it, much as he wanted to get on the trail of the thieves.

There was a scurrying on the part of the hotel attendants to close the windows, and the guests who had been enjoying the air out on the porches came running in. With a rush, a roar and a muttering, as peal after peal of thunder sounded, the deluge continued.

"It's a good thing we didn't start," observed Ned.

"I should say so," agreed Tom. "But we'll get off the first thing in the morning, dad."

Mr. Swift did not reply, but his nervous pacing to and fro in the hotel office showed how anxious he was to be at home again. There was no help for it, however, and, after a time, finding that to think of reaching his house that night was out of the question, the inventor calmed down somewhat.

The storm continued nearly all night, as Tom could bear witness, for he did not sleep well, nor did his father. And when he came down to breakfast in the morning Mr. Swift plainly showed the effects of the bad news. His face was haggard and drawn and his eyes smarted and burned from lack of sleep.

"Well, Tom, we must start early," he said nervously. "I am glad it has cleared off. Is the boat all ready?"

"Yes, and it's a good thing it was under shelter last night or we'd have to bail it out now, and that would delay us."

An hour later they were under way, having telephoned to the engineer at the Swift home that they were coming. Garret Jackson reported over the wire that he had notified the Shopton police of the robbery, but that little could be done until the inventor arrived to give a description of the stolen articles.

"And that will do little good, I fear," remarked Tom. "Those fellows have evidently been planning this for some time and will cover their tracks well. I'd like to catch them, not only to recover your things, dad, but to find out the mystery of my boat and why the man took the tank braces."



CHAPTER XXI

THE BALLOON ON FIRE

Down Lake Carlopa speeded the ARROW, those on board watching the banks slip past as the motor-boat rapidly cut through the water.

"What time do you think we ought to reach home, Tom?" asked Mr. Swift.

"Oh, about four o'clock, if we don't stop for lunch."

"Then we'll not stop," decided the inventor. "We'll eat what we have on board. I suppose you have some rations?" and he smiled, the first time since hearing the bad news.

"Oh, yes, Ned and I didn't eat everything on our camping trips," and Tom was glad to note that the fine weather which followed the storm was having a good effect on his father.

"We certainly had a good time," remarked Ned. "I don't know when I've enjoyed a vacation so."

"It's too bad it had to be cut short by this robbery," commented Mr. Swift.

"Oh, well, my time would be up in a few days more," went on the young bank employee. "It's just as well to start back now."

Tom took the shortest route he knew, keeping in as close to shore as he dared, for now he was as anxious to get home as was his father. On and on speeded the ARROW, yet fast as it was, it seemed slow to Mr. Swift, who, like all nervous persons, always wanted to go wherever he desired to go instantly.

Tom headed his boat around a little point of land, and was urging the engine to the top notch of speed, for now he was on a clear course, with no danger from shoals or hidden rocks, when he saw, darting out from shore, a tiny craft which somehow seemed familiar to him. He recognized a peculiar put-putter of the motor.

"That's the DOT," he remarked in a low voice to Ned, "Miss Nestor's cousin's boat."

"Is she in it now?" asked Ned.

"Yes," answered Tom quickly.

"You've got good eyesight," remarked Ned dryly, "to tell a girl at that distance. It looks to me like a boy."

"No, it's Mary—I mean Miss Nestor," the youth quickly corrected himself, and a close observer would have noticed that he blushed a bit under his coat of tan.

Ned laughed, Tom blushed still more, and Mr. Swift, who was in a stern seat, glanced up quickly.

"It looks as if that boat wanted to hail us," the inventor remarked.

Tom was thinking the same thing, for, though he had changed his course slightly since sighting the DOT, the little craft was put over so as to meet him. Wondering what Miss Nestor could want, but being only too willing to have a chat with her, the young inventor shifted his helm. In a short time the two craft were within hailing distance.

"How do you do?" called Miss Nestor, as she slowed down her motor. "Don't you think I'm improving, Mr. Swift?"

"What's that? I—er—I beg your pardon, but I didn't catch that," exclaimed the aged inventor quickly, coming out of a sort of day-dream. "I beg your pardon." He thought she had addressed him.

Miss Nestor blushed and looked questioningly at Tom.

"My father," he explained as he introduced his parent. Ned needed none, having met Miss Nestor before. "Indeed you have improved very much," went on our hero. "You seem able to manage the boat all alone."

"Yes, I'm doing pretty well. Dick lets me take the DOT whenever I want to, and I thought I'd come out for a little trial run this morning. I'm getting ready for the races. I suppose you are going to enter them?" and she steered her boat alongside Tom's, who throttled down his powerful motor so as not to pass his friend.

"Races? I hadn't heard of them," he replied.

"Oh, indeed there are to be fine ones under the auspices of the Lanton Motor Club. Mr. Hastings, of whom you bought that boat, is going to enter his new CARLOPA, and Dick has entered the DOT, in the baby class of course. But I'm going to run it, and that's why I'm practicing."

"I hope you win," remarked Tom. "I hadn't heard of the races, but I think I'll enter. I'm glad you told me. Do you want to race now?" and he laughed as he looked into the brown eyes of Mary Nestor.

"No, indeed, unless you give me a start of several miles."

They kept together for some little time longer, and then, as Tom knew his father would be restless at the slow speed, he told Miss Nestor the need of haste, and, advancing his timer, he soon left the DOT behind. The girl called a laughing good-by and urged him not to forget the races, which were to take place in about two weeks.

"I suppose Andy Foger will enter his boat," commented Ned.

"Naturally," agreed Tom. "It's a racer, and he'll probably think it can beat anything on the lake. But if he doesn't manage his motor differently, it won't."

The distance from Sandport to Shopton had been more than half covered at noon, when the travelers ate a lunch in the boat. Mr. Swift was looking anxiously ahead to catch the first glimpse of his dock and Tom was adjusting the machinery as finely as he dared to get out of it the maximum speed.

Ned Newton, who happened to be gazing aloft, wondering at the perfect beauty of the blue sky after the storm, uttered a sudden exclamation. Then he arose and pointed at some object in the air.

"Look!" he cried, "A balloon! It must have gone up from some fair."

Tom and his father looked upward. High in the air, almost over their heads, was an immense balloon. It was of the hot-air variety, such as performers use in which to make ascensions from fair grounds and circuses, and below it dangled a trapeze, upon which could be observed a man, only he looked more like a doll than a human being.

"I shouldn't like to be as high as that," remarked Ned.

"I would," answered Tom as he slowed down the engine the better to watch the balloon. "I'd like to go up in an airship, and I intend to some day."

"I believe he's going to jump!" suddenly exclaimed Ned after a few minutes. "He's going to do something, anyhow."

"Probably come down in a parachute," said Tom. "They generally do that."

"No! No!" cried Ned. "He isn't going to jump. Something has happened! The balloon is on fire! He'll be burned to death!"

Horror stricken, they all gazed aloft. From the mouth of the balloon there shot a tongue of fire, and it was followed by a cloud of black smoke. The big bag was getting smaller and seemed to be descending, while the man on the trapeze was hanging downward by his hands to get as far as possible away from the terrible heat.



CHAPTER XXII

THE RESCUE

"Jump! Jump!" cried Mr. Swift, leaping to his feet and motioning to the man on the trapeze of the balloon. But it is doubtful whether or not the performer heard him. Certainly he could not see the frantic motions of the inventor. "Why doesn't he jump?" Mr. Swift went on piteously to the two lads. "He'll surely be burned to death if he hangs on there!"

"It's too far to leap!" exclaimed Tom. "He's a good way up in the air, though it looks like only a short distance. He would be killed if he dropped now."

"He ought to have a parachute," added Ned. "Most of those men do when they go up in a balloon. Why doesn't he come down in that? I wonder how the balloon took fire?"

"Maybe he hasn't a parachute," suggested Tom, while he slowed down the motor-boat still more so as to remain very nearly under the blazing balloon.

"Yes, he has!" cried Ned. "See, it's hanging to one side of the big bag. He ought to cut loose. He could save himself then. Why doesn't he?"

The balloon was slowly twisting about, gradually settling to the surface of the lake, but all the while the flames were becoming fiercer and the black clouds of smoke increased in size.

"There, see the parachute!" went on Ned.

The twisting of the bag had brought into view the parachute or big, umbrella-shaped bag, which would have enabled the man to safely drop to the surface of the lake. Without it he would have hit the water with such force that he would have been killed as surely as if he had struck the solid earth. But the boys and Mr. Swift also saw something else, and this was that the balloon was on fire on the same side where the parachute was suspended.

"Look! Look!" shouted Tom, bringing his boat to a stop. "That's why he can't jump! He can't reach the parachute!"

By this time the balloon had settled so low that the actions of the man could be plainly seen. That he was in great agony of fear, as well as in great pain from the terrific heat over his head was evident. He shifted about on the trapeze bar, now hanging by one hand, so as to bring his body a little farther below the blazing end of the bag, then, when one arm tired, he would hang by the other. If the balloon would only come down more quickly it would get to within such a short distance of the water that the man could safely make the drop. But the immense canvas bag was settling so slowly, for it was still very buoyant, that considerable time must elapse before it would be near enough to the water to make it safe for the unfortunate man to let go the trapeze.

"Oh, if we could only do something!" cried Tom. "We have to remain here helpless and watch him burn to death. It's awful!"

The three in the boat continued to gaze upward. They could see the man making frantic efforts to reach his parachute from time to time. Once, as a little current of air blew the flames and smoke to one side, he thought he had a chance. Up on the trapeze bar he pulled himself and then edged along it in an endeavor to grasp the ring of the parachute. Once he almost had hold of that and also the cord, which ran to a knife blade. This cord, being pulled, would sever the rope that bound it to the balloon, and he would be comparatively safe, so he might drop to the lake. But, just as he was about to grasp the ring and cord the smoke came swirling down on him and the hungry flames seemed to put out their fiery tongues to devour him. He had to slide back and once more hung by his hands.

"I thought he was saved then," whispered Tom, and even the whisper sounded loud in the silence.

Several men came running along the shore of the lake now. They saw the occupants in the ARROW and cried out:

"Why don't you save him? Go to his rescue!"

"What can we do?" asked Ned quietly of his two friends, but he did not trouble to answer the men on shore, who probably did not know what they were saying.

The motor-boat had drifted from a spot under the unfortunate balloonist, and at a word from his father the young inventor started the engine and steered the craft back directly under the blazing bag again.

"If he does drop, perhaps we may be able to pick him up," said Mr. Swift. "I wish we could save him!"

A cry from Ned startled Tom and his father, and their eyes, that had momentarily been directed away from the burning bag high in the air, were again turned toward it.

"The balloon is falling apart!" exclaimed Ned. "It's all up with him now!"

Indeed it did seem so, for pieces of the burning canvas, blazing and smoking, were falling in a shower from the part of the bag already consumed, and the fiery particles were fairly raining down on the man. But he still had his wits about him, though his perilous position was enough to make any one lose his mind, and he swung from side to side on the bar, shifting skillfully with his hands and dodging the larger particles of blazing canvas. When some small sparks fell on his clothing he beat them out with one hand, while with the other he clung to the trapeze.

There was scarcely any wind or the man's plight might have been more bearable, for the current of air would have carried the smoke and fire to one side. As it was, most of the smoke and flames went straight up, save now and then, when a draught created by the heat would swirl the black clouds down on the performer, hiding him from sight for a second or two. A breeze would have carried the sparks away instead of letting them fall on him.

Nearer and nearer to the surface of the lake sank the balloon. By this time the crowd on the bank had increased and there were excited opinions as to what was best to do. But the trouble was that little could be done. If the man could hold out until he got near enough to the water to let go he might yet be saved, but this would not be for some time at the present rate the balloon was falling. The performer realized this, and, as the fire was getting hotter, he made another desperate attempt to reach the parachute. It was unavailing and he had to drop back, hanging below the slender bar.

Suddenly there came a puff of wind, fanning the faces of those in the motor-boat, and they looked intently to observe if there was any current as high as was the balloonist. They saw the big bag sway to one side and the flames broke out more fiercely as they caught the draught. The balloon moved slowly down the lake.

"Keep after it, Tom!" urged his father. "We may be able to save him!"

The lad increased the speed of his engine and Ned, who was at the wheel, gave it a little twist. Then, with a suddenness that was startling, the blazing canvas airship began to settle swiftly toward the water. It had lost much of its buoyancy.

"Now he can jump! He's near enough to the water now!" cried Tom.

But a new danger arose. True, the balloon was rapidly approaching the surface of the lake and in a few seconds more would be within such a short distance that a leap would not be fatal. But the burning bag was coming straight down and scarcely would the man be in the water ere the fiery canvas mass would be on top of him.

In such an event he would either be burned to death or so held down that drowning must quickly follow.

"If there was only wind enough to carry the balloon beyond him after he jumped he could do it safely!" cried Ned.

Tom said nothing. He was measuring, with, his eye, the distance the balloon had yet to go and also the distance away the motor-boat was from where it would probably land.

"He can do it!" exclaimed the young inventor.

"How?" asked his father.

For answer Tom caught up a newspaper he had purchased at the hotel that morning. Rolling it quickly into a cone, so that it formed a rough megaphone, he put the smaller end to his mouth, and, pointing the larger opening at the balloonist, he called out:

"Drop into the lake! We'll pick you up before the bag falls on you! Jump! Let go now!"

The balloonist heard and understood. So did Ned and Mr. Swift. Tom's quick wit had found a way to save the man.

Faster and faster the blazing bag settled toward the surface of the water. It was now merely a mushroom-shaped piece of burning and smoking canvas, yet it was supporting the man almost as a parachute would have done.

With one look upward to the burning mass above him and a glance downward to the lake, the aeronaut let go his hold. Like a shot he came down, holding his body rigid and straight as a stick, for he knew how to fall into water, did that balloonist.

Tom Swift was ready for him. No sooner had the lad called his directions through the megaphone than the young inventor had speeded up his engine to the top notch.

"Steer so as to pick him up!" Tom cried to Ned, who was at the wheel. "Pass by him on a curve, and, as soon as I grab him, put the wheel over so as to get out from under the balloon."

It was a risky thing to do, but our hero had it all planned out. He made a loop of the boat's painter, and, hurrying to the bow, leaned over as far as he could, holding the rope in readiness. His idea was to have the balloonist grab the strands and be pulled out of danger by the speedy motor-boat, for the blazing canvas would cover such an extent of water that the man could not have swum out of the danger zone in time.

Down shot the balloonist and down more slowly settled the collapsed bag, yet not so slowly that there was any time to spare. It needed only a few seconds to drop over the performer, to burn and smother him.

Into the water splashed the man, disappearing from sight as when a stick is dropped in, point first. Ned was alert and steered the boat to the side in which the man's face was, for he concluded that the aeronaut would strike out in that direction when he came up. The ARROW was now directly under the blazing balloon and cries of fear from the watchers on shore urged upon Tom and his companions the danger of their position. But they had to take some risk to rescue the man.

"There he is!" cried Mr. Swift, who was on the watch, leaning over the side of the boat. Tom and Ned saw him at the same instant. Ned shifted his wheel and the young inventor bent over, holding out the rope for the man to grasp. He saw it and struck out toward the ARROW. But there was no need for him to go far. An instant more and the speeding motor-boat shot past him. He grabbed the rope and Tom, aided by Mr. Swift, began to lift him out of the water.

"Quick! To one side, Ned!" yelled Tom, for the heat of the descending mass of burning canvas struck him like a furnace blast.

Ned needed no urging. With a swirl of the screw the ARROW shot herself out of the way, carrying the aeronaut with her. A moment later the burning balloon, or what there was left of it, settled down into the lake, hissing angrily as the fire was quenched by the water and completely covering the spot where, but a few seconds before, the man had been swimming. He had been saved in the nick of time.



CHAPTER XXIII

PLANS FOR AN AIRSHIP

"Slow her down, Ned!" cried Tom, for the ARROW was shooting so swiftly through the water that the young inventor found it impossible to pull up the balloonist. Ned hurried back to the motor, and, when the boat's way had been checked, it was an easy matter to pull the dripping and almost exhausted man into the craft.

"Are you much hurt?" asked Mr. Swift anxiously, for Tom was too much out of breath with his exertion to ask any questions. For that matter the man was in almost as bad a plight. He was breathing heavily, as one who had run a long race.

"I—I guess I'm all right," he panted. "Only burned a little on my hands. That—that was a close call!"

The boat swung around and headed for shore, on which was quite a throng of persons. Some of them had cheered when they saw the plucky rescue.

"I'm afraid we can't save your balloon," gasped Tom as he looked at the place where the canvas was still floating and burning.

"No matter. It wasn't worth much. That's the last time I'll ever go up in a hot-air balloon," said the man with more energy than he had before exhibited. "I'm done with 'em. I've had my lesson. Hereafter an aeroplane or a gas balloon for me. I only did this to oblige the fair committee. I'll not do it again."

The man spoke in short, crisp sentences, as though he was in too much of a hurry to waste his words.

"Let it sink," he went on. "It's no good. Glad to see the last of it."

Almost as he spoke, with a final hiss and a cloud of steam that mingled with the black smoke, the remains of the big bag sunk beneath the surface of the lake.

"We must get you ashore at once and to a doctor," said Mr. Swift. "You must be badly burned."

"Not much. Only my hands, where some burning pieces of canvas fell on' em. If I had a little oil to put on I'd be all right."

"I can fix you up better than that," put in Tom. "I have some Vaseline."

"Good! Just the thing. Pass it over," and the man, though he spoke shortly, seemed grateful for the offer. "My name's Sharp," he went on, "John Sharp, of no place in particular, for I travel all over. I'm a professional balloonist. Ha! That's the stuff!"

This last was in reference to a bottle of Vaseline, which Tom produced. Mr. Sharp spread some over the backs of his hands and went on:

"That's better. Much obliged. I can't begin to thank you for what you did for me—saved my life. I thought it was all up with me—would have been but for you. Mustn't mind my manner—it's a way I have—have to talk quick when you're balloonin'—no time—but I'm grateful all the same. Who might you people be?"

Tom told him their names and Mr. Swift asked the aeronaut if he was sure he didn't need the services of a physician.

"No doctor for me," answered the balloonist. "I've been in lots of tight places, but this was the worst squeeze. If you'll put me ashore, I guess I can manage now."

"But you're all wet," objected Tom. "Where will you go? You need some other clothes," for the man wore a suit of tights and spangles.

"Oh, I'm used to this," went on the performer. "I frequently have to fall in the water. I always carry a little money with me so as to get back to the place where I started from. By the way, where am I?"

"Opposite Daleton," answered Tom. "Where did you go up from?"

"Pratonia. Big fair there. I was one of the features."

"Then you're about fifteen miles away," commented Mr. Swift. "You can hardly get back before night. Must you go there?"

"Left my clothes there. Also a valuable gas balloon. No more hot-air ones for me. Guess I'd better go back," and the aeronaut continued to speak in his quick, jerky sentences.

"We'd be very glad to have you come with us, Mr. Sharp," went on the inventor. "We are not far from Shopton, and if you would like to remain over night I'm sure we would make you comfortable. You can proceed to Pratonia in the morning."

"Thanks. Might not be a bad idea," said Mr. Sharp. "I'm obliged to you. I've got to go there to collect my money, though I suppose they won't give it all to me."

"Why not?" demanded Ned.

"Didn't drop from my parachute. Couldn't. Fire was one reason—couldn't reach the parachute, and if I could have, guess it wouldn't have been safe. Parachute probably was burned too. But I'm done with hot-air balloons though I guess I said that before."

The boys were much interested in the somewhat odd performer, and, on his part, he seemed to take quite a notion to Tom, who told him of several things that he had invented. "Well," remarked Mr. Swift after a while, during which the boat had been moving slowly down the lake, "if we are not to go ashore for a doctor for you, Mr. Sharp, suppose we put on more speed and get to my home? I'm anxious about a robbery that occurred there," and he related some facts in the case.

"Speed her up!" exclaimed Mr. Sharp. "Wish I could help you catch the scoundrels, but afraid I can't—hands too sore," and he looked at his burns. Then he told how he had made the ascension from the Pratonia fair grounds and how, when he was high in the air, he had discovered that the balloon was on fire. He described his sensations and told how he thought his time had surely come. Sparks from the hot air used to inflate it probably caused the blaze, he said.

"I've made a number of trips," he concluded, "hot air and gas bags, but this was the worst ever. It got on my nerves for a few minutes," he added coolly.

"I should think it would," agreed Tom as he speeded up the motor and sent the ARROW on her homeward way.

The boys and Mr. Swift were much interested in the experiences of the balloonist and asked him many questions, which he answered modestly. Several hours passed and late that afternoon the party approached Shopton.

"Here we are!" exclaimed Mr. Swift, relief in his tones. "Now to see of what I have been robbed and to get the police after the scoundrels!"

When the boat was nearing the dock Mr. Sharp, who had been silent for some time, suddenly turned to Tom and asked:

"Ever invent an airship?"

"No," replied the lad, somewhat surprised. "I never did."

"I have," went on the balloonist. "That is, I've invented part of it. I'm stuck over some details. Maybe you and I'll finish it some day. How about it?"

"Maybe," assented Tom, who was occupied just then in making a good landing. "I am interested in airships, but I never thought I could build one."

"Easiest thing in the world," went on Mr. Sharp, as if it was an everyday matter. "You and I will get busy as soon as we clear up this robbery." He talked as though he had been a friend of the family for some time, for he had a genial, taking manner.

A little later Mr. Swift was excitedly questioning Garret Jackson concerning the robbery and making an examination of the electrical shop to discover what was missing.

"They've taken some parts of my gyroscope!" he exclaimed, "and some valuable tools and papers, as well as some unfinished work that will be difficult to replace."

"Much of a loss?" asked Mr. Sharp with a business-like air.

"Well, not so large as regards money," answered the inventor, "but they took things I can never replace, and I will miss them very much if I cannot get them back."

"Then we'll get them back!" snapped the balloonist, as if that was all there was to it.

The police were called up on the telephone and the facts given to them, as well as a description of the stolen things. They promised to do what they could, but, in the light of past experiences, Tom and his father did not think this would be much. There was little more that could be done that evening. Ned Newton went to his home, and, after Mr. Swift had insisted in calling in his physician to look after Mr. Sharp's burns the balloonist was given a room next to Tom's. Then the Swift household settled down.

"Well," remarked Tom to his father, as he got ready for bed, "this sure has been an exciting day."

"And my loss is a serious one," added the inventor somewhat sadly.

"Don't worry, dad," begged his son. "I'll do my best to recover those things for you."

Several days passed, but there was no clew to the thieves. That they were the same ones who had stolen the turbine model there was little doubt, but they seemed to have covered their tracks well. The police were at a loss, and, though Tom and Mr. Sharp cruised about the lake, they could get no trace of the men. The balloonist had sent to Pratonia for his clothing and other baggage and was now installed in the Swift home, where he was invited to stay a week or two.

One night when he was looking over some papers he had taken from his trunk the balloonist came over to where Tom was making a drawing of a new machine he was planning and said:

"Like to see my idea for an airship? Different from some. It's a dirigible balloon with an aeroplane front and rear to steer and balance it in big winds. It would be a winner, only for one thing. Maybe you can help me."

"Maybe I can," agreed Tom, who was at once interested.

"We ought to be able to do something. Look at our names—Swift and Sharp—quick and penetrating—a good firm to build airships," and he laughed genially. "Shall we do it?"

"I'm willing," agreed Tom, and the balloonist spread his plans out on the table, he and the young inventor soon being deep in a discussion of them.



CHAPTER XXIV

THE MYSTERY SOLVED

From then on, for several days, the young inventor and his new friend lived in an atmosphere of airships. They talked them from morning until night, and even Mr. Swift, much as he was exercised over his loss, took part in the discussions.

In the meanwhile efforts had not ceased to locate the robbers and recover the stolen goods, but so far without success.

One afternoon, about two weeks after the thrilling rescue of John Sharp, Tom said to the balloonist:

"Wouldn't you like to come for a ride in the motor-boat? Maybe it will help us to solve the puzzle of the airship. We'll take a trip across and up the opposite shore."

"Good idea," commented Mr. Sharp. "Fine day for a sail. Come on. Blow the cobwebs from our brains."

Mr. Swift declined an invitation to accompany them, as he said he would stay home and try to straighten out his affairs, which were somewhat muddled by the robbery.

Out over the blue waters of Lake Carlopa shot the ARROW. It was making only moderate speed, as Tom was in no hurry, and he knew his engine would last longer if not forced too frequently. They glided along, crossed the lake and were proceeding up the opposite shore when, as they turned out from a little bay and rounded a point of land, Mr. Sharp exclaimed:

"Look out, Tom, there's rowboat just ahead!"

"Oh, I'll pass well to one side of that," answered the young inventor, looking at the craft. As he did so, noting that there were four men in it, one of the occupants caught a glimpse of the ARROW. No sooner had he done so than he spoke to his companions, and they all turned to stare at Tom. At first the lad could scarcely believe his eyes, but as he looked more intently he uttered a cry.

"There they are!"

"Who?" inquired Mr. Sharp.

"Those men—the thieves! We must catch them!"

Tom had spoken loudly, but even though the men in the rowboat did hear what he said, they would have realized without that that they were about to be pursued, for there was no mistaking the attitude of our hero.

Two of the thieves were at the oars, and, with one accord, they at once increased their speed. The boat swung about sharply and was headed for the shore, which they seemed to have come from only a short time previous, as the craft was not far out in the lake.

"No, you don't!" cried Tom. "I see your game! You want to get to the woods, where you'll have a better chance to escape! If this isn't great luck, coming upon them this way!"

It was the work of but a moment to speed up the engine and head the ARROW for the rowboat. The men were pulling frantically, but they had no chance.

"Get between them and the shore!" cried Mr. Sharp. "You can head them off then." This was good advice and Tom followed it. The men, among whom the lad could recognize Happy Harry and Anson Morse, were all excited. Two of them stood up, as though to jump overboard, but their companions called to them to stop.

"If we only had a gun now, not to shoot at them but to intimidate them," murmured the balloonist, "maybe they'd stop."

"Here's one," answered Tom, pointing to the seat locker, where he kept the shotgun Mr. Duncan had given him. In a moment Mr. Sharp had it out.

"Surrender!" he cried, pointing the weapon at the men in the small boat.

"Don't shoot! Don't fire on us! We'll give up!" cried Happy Harry, and the two with the oars ceased pulling.

"Don't take any chances," urged Mr. Sharp in a low voice. "Keep between them and the shore. I'll cover them." Tom was steering from an auxiliary side wheel near the motor, and soon the ARROW had cut off the retreat of the men. They could not land and to row across the lake meant speedy capture.

"Well, what do you want of us?" growled Morse. "What right have you got to interfere with us in this fashion?"

"The best of right," answered Tom. "You'll find out when you're landed in jail."

"You can't arrest us," sneered Happy Harry. "You're not an officer and you haven't any warrant."

Tom hadn't thought of that, and his chagrin showed in his face. Happy Harry was quick to see it.

"You'd better let us go," he threatened "We can have you arrested for bothering us. You haven't any right to stop us, Tom Swift."

"Maybe he hasn't, but I have!" exclaimed John Sharp suddenly.

"You! Who are you?" demanded Featherton, alias Simpson, the man who had run the automobile that carried Tom away.

"Me. I'm a special deputy sheriff for this county," answered the balloonist simply. "Here's my badge," and, throwing back his coat, he displayed it. "You see I got the appointment in order to have some authority in the crowds that gather to watch me go up," he explained to Tom, who plainly showed his astonishment. "I found it very useful to be able to threaten arrest, but in this case I'll do more than threaten. You are my prisoners," he went on to the men in the boat, and he handled the shotgun as if he knew how to use it. "I'll take you into custody on complaint of Mr. Swift for robbery. Now will you go quietly or are you going to make a fuss?" and Mr. Sharp shut his jaw grimly.

"Well, seeing as how you have the drop on us, I guess we'll have to do as you say," admitted Happy Harry, alias Jim Burke. "But you can't prove anything against us. We haven't any of Mr. Swift's property."

"Well, you know where it is then," retorted Tom quickly.

Under the restraining influence of the gun the men made no resistance. While Mr. Sharp covered them, Tom towed their boat toward shore. Then, while the young inventor held the gun, the balloonist tied the hands and feet of the thieves in a most scientific manner, for what he did not know about ropes and knots was not worth putting into a book.

"Now, I guess they'll stay quiet for a while," remarked Mr. Sharp as he surveyed the crestfallen criminals. "I'll remain on guard here, Tom, while you go notify the nearest constable and we'll take them to jail. We bagged the whole lot as neatly as could be desired."

"No, you didn't get all of us!" exclaimed Happy Harry, and there was a savage anger in his tones.

"Keep quiet!" urged Morse.

"No, I'll not keep quiet! It's a shame that we have to take our medicine while that trimmer, Tod Boreck, goes free. He ought to have been with us, and he would be, only he's trying to get away with that sparkler!"

"Keep quiet," again urged Morse.

Tom was all attention. He had caught the word "sparkler," and he at once associated it with the occasion he had heard the men use it before. He felt that he was on the track of solving the mystery connected with his boat.

He looked at the men. They were the same four who had been involved in the former theft—Appleson, Featherton, Morse and Burke. Were there five of them? He recalled the man who had been caught tampering with his boat—the man who had tried to bid on the ARROW at the auction. Where was he?

"Boreck didn't get what he was after," resumed Happy Harry, "and I'm going to spoil his game for him. Say, kid," he went on to Tom, "look in the front part of your boat—where the gasoline tank is."

Tom felt his heart beating fast. At last he felt that he would solve the puzzle. He opened the forward compartment. To his disappointment it seemed as usual. Morse and the others were making a vain effort to silence Happy Harry.

"I don't see anything here," said Tom.

"No, because it's hidden in one of those blocks of wood you use for a brace," continued the man. "Which one it is, Boreck didn't know, so he pulled out two or three, only to be fooled each time. You must have shifted them, kid, from the way they were when we had the boat."

"I did," answered the young inventor, recollecting how he had taken out some of the braces and inserted new ones, then painted the interior of the compartment. "What is in the braces, anyhow?"

"The sparkler—a big diamond—in a hollow place in the wood, kid!" exclaimed Happy Harry, blurting out the words. "I'm not going to let Tod Boreck get away with it while we stay in jail."

"Take out all the braces that haven't been moved and have a look," suggested Mr. Sharp. Tom only had to remove two, those farthest back, for all the others had, at one time or another, been changed or taken away by the thief.

One of the blocks did not seem to have anything unusual about it, but at the sight of the other Tom could not repress a cry. It was the one that seemed to have had a hole bored in it and then plugged up again. He remembered his father noticing it on the occasion of overhauling the boat.

"The sparkler's in there," said the tramp as he saw the brace. "Boreck was after it several times, but he never pulled out the right one."

With his knife Tom dug out the putty that covered the round hole in the block. No sooner had he done so than there rolled out into his hand a white object. It was something done up in tissue paper, and as he removed the wrapper, there was a flash in the sunlight and a large, beautiful diamond was revealed. The mystery had been solved.



CHAPTER XXV

WINNING A RACE

"Where did this diamond come from?" demanded Mr. Sharp of the quartette of criminals.

"That's for us to know and you to find out," sneered Happy Harry. "I don't care as long as that trimmer Boreck didn't get it. He tried to do us out of our share."

"Well, I guess the police will make you tell," went on the balloonist. "Go for the constable, Tom."

Leaving his friend to guard the ugly men, who for a time at least were beyond the possibility of doing harm, Tom hurried off through the woods to the nearest village. There he found an officer and the gang was soon lodged in jail. The diamond was turned over to the authorities, who said they would soon locate the owner.

Nor were they long in doing it, for it appeared the gem was part of a large jewel robbery that had taken place some time before in a distant city. The Happy Harry gang, as the men came to be called, were implicated in it, though they got only a small share of the plunder. Search was made for Tod Boreck and he was captured about a week after his companions. Seeing that their game was up, the men made a partial confession, telling where Mr. Swift's goods had been secreted, and the inventor's valuable tools, papers and machinery were recovered, no damage having been done to them.

It developed that after the diamond theft, and when the gang still had possession of Mr. Hastings' boat, Boreck, sometimes called Murdock by his cronies, unknown to them, had secreted the jewel in one of the braces under the gasoline tank. He expected to get it out secretly, but the capture of the gang and the sale of the boat prevented this. Then he tried to buy the craft to take out the diamond, but Tom overbid him. It was Boreck who found Andy's bunch of keys and used one to open the compartment lock when Tom surprised him. The man did manage to remove some of the blocks, thinking he had the one with the diamond in it, but the fact of Tom changing them, and painting the compartment deceived him. The gang hoped to get some valuables from Mr. Swift's shops, and, to a certain extent, succeeded after hanging around for several nights and following him to Sandport, but Tom eventually proved too much for them. Even stealing the Arrow, which was taken to aid the gang in robbing Mr. Swift, did not succeed, and Boreck's plan then to get possession of the diamond fell through.

It was thought that the gang would get long terms in prison, but one night, during a violent storm, they escaped from the local jail and that was the last seen of them for some time.

A few days after the capture as Tom was in the boathouse making some minor repairs to the motor he heard a voice calling:

"Mistah Swift, am yo' about?"

"Hello, Rad, is that you?" he inquired, recognizing the voice of the colored owner of the mule Boomerang.

"Yais, sa, dat's me. I got a lettah fo' yo'. I were passin' de post-office an' de clerk asted me to brung it to yo' 'case as how it's marked 'hurry,' an' he said he hadn't seen yo' to-day."

"That's right. I've been so busy I haven't had time to go for the mail," and Tom took the letter, giving Eradicate ten cents for his trouble.

"Ha, that's good!" exclaimed Tom as he read it.

"Hab some one done gone an' left yo' a fortune, Mistah Swift?" asked the negro.

"No, but it's almost as good. It's an invitation to take part in the motor-boat races next week. I'd forgotten all about them. I must get ready."

"Good land! Dat's all de risin' generation t'inks about now," observed Eradicate, "racin' an' goin' fast. Mah ole mule Boomerang am good enough fo' me," and, shaking his head in a woeful manner, Eradicate went on his way.

Tom told Mr. Sharp and his father of the proposed races of the Lanton Motor-boat Club, and, as it was required that two persons be in a craft the size of the ARROW, the young inventor arranged for the balloonist to accompany him. Our hero spent the next few days in tuning up his motor and in getting the ARROW ready for the contest.

The races took place on that side of Lake Carlopa near where Mr. Hastings lived, and he was one of the officials of the club. There were several classes, graded according to the horsepower of the motors, and Tom found himself in a class with Andy Foger.

"Here's where I beat you," boasted the red-haired youth exultantly, though his manner toward Tom was more temperate than usual. Andy had learned a lesson.

"Well, if you can beat me I'll give you credit for it," answered Tom.

The first race was for high-powered craft, and in this Mr. Hastings' new CARLOPA won. Then came the trial of the small boats, and Tom was pleased to note that Miss Nestor was on hand in the tiny DOT.

"Good luck!" he called to her as he was adjusting his timer, for his turn would come soon. "Remember what I told you about the spark," for he had given her a few lessons.

"If I win it will be due to you," she called brightly.

She did win, coming in ahead of several confident lads who had better boats. But Miss Nestor handled the DOT to perfection and crossed the line a boat's length ahead of her nearest competitor.

"Fine!" cried Tom, and then came the warning gun that told him to get ready for his trial.

This was a five-mile race and had several entrants. The affair was a handicap one and Tom had no reason to complain of the rating allowed him.

"Crack!" went the starting pistol and away went Tom and one or two others who had the same allowance as did he. A little later the others started and finally the last class, including Andy Foger. The RED STREAK shot ahead and was soon in the lead, for Andy and Sam had learned better how to handle their craft. Tom and Mr. Sharp were worried, but they stuck grimly to the race and when the turning stake was reached Tom's motor had so warmed up and was running so well that he crept up on Andy. A mile from the final mark Andy and Tom were on even terms, and though the red-haired lad tried to shake off his rival he could not. Andy's ignition system failed him several times and he changed from batteries to magneto and back again in the hope of getting a little more speed out of the motor.

But it was not to be. A half-mile away from the finish Tom, who had fallen behind a little, crept up on even terms. Then he slowly forged ahead, and, a hundred rods from the stake, the young inventor knew that the race was his. He clinched it a few minutes later, crossing the line amid a burst of cheers. The ARROW had beaten several boats out of her own class and Tom was very proud and happy.

"My, but we certainly did scoot along some!" cried Mr. Sharp. "But that's nothing to how we'll go when we build our airship, eh, Tom?" and he looked at the flushed face of the lad.

"No, indeed," agreed the young inventor. "But I don't know that we'll take part in any races in it. We'll build it, however, as soon as we can solve that one difficulty."

They did solve it, as will be told in the next book of this series, to be called "Tom Swift and His Airship; or, The Stirring Cruise of the RED CLOUD." They had some remarkable adventures in the wonderful craft, and solved the mystery of a great bank robbery.

This ended the contests of the motor-boats and the little fleet crowded up to the floats and docks, where the prizes were to be awarded. Tom received a handsome silver cup and Miss Nestor a gold bracelet.

"Now I want all the contestants, winners and losers, to come up to my house and have lunch," invited Mr. Hastings.

As Tom and the balloonist strolled up the walk to the handsome house Andy Foger passed them.

"You wouldn't have beaten me if my spark coil hadn't gone back on me," he said, somewhat sneeringly.

"Maybe," admitted Tom, and just then he caught sight of Mary Nestor. "May I take you in to lunch?" he asked.

"Yes," she said, "because you helped me to win," and she blushed prettily. And then they all sat down to the tables set out on the lawn, while Tom looked so often at Mary Nestor that Mr. Sharp said afterward it was a wonder he found time to eat. But Tom didn't care. He was happy.

THE END