"Then you want me, and perhaps Mr. Damon to take the stuff up in the machine? Excuse me. I don't believe I care to run an airship myself."

"No," went on Tom, "there isn't any question of an airship this time. No one is going up. Come on out into the yard and I'll show you."

Ned Newton followed his chum out into the big yard near one of the shops. Erected in it, and evidently a new structure, was a large wooden scaffold in square tower shape with a long overhanging arm and a platform on the extremity. Beneath it was a pit dug in the earth, and in this pit, which was directly under the outstanding arm of the tower, was a pile of wood and shavings, oil-soaked.

"Oh, I see the game," remarked Ned. "You're going to drop the stuff from this height instead of doing it from an airship."

"Yes," Tom answered. "There will be time enough to go on with the airship end of it after I get the right combination of chemicals. And by having a metal container with the stuff in dropped from this frame work, I can station myself as near the burning pit as I can get and watch what happens."

"It's a good idea," decided Ned. "I wonder you didn't try that before."

"Mr. Baxter suggested it," replied Tom. "That helpful idea more than pays me for what I have done for him. So now, if you're ready, I'd like to have you watch with me and make some notes, one of us on one side of the pit, and one on the other. There are always two sides to a fire, the leeward and the windward, and I want to see how my chemicals act in both positions."

"I'm with you," said Ned. "Who's going to drop the stuff—Koku?"

"No, he is a bit too heavy for the framework, which I had put up in a hurry. I'd have Rad do it, but he's out of the game."

"Poor old Rad!" murmured Ned. "Do you think he'll ever get better, Tom?"

"I don't know," sighed the young inventor. "All I can do is to hope. He is very patient, and Koku is devoted to him. All their little bickerings and squabbles seem to have been forgotten."

Tom called some of his workmen, some of them to start the blaze of inflammable material in the pit, while one climbed up to the top of the tower of scantlings and made his way out on the extended arm, where there was a little platform for him to stand until it was time to drop the chemicals.

"Light her up!" cried Tom Swift, and a match was thrown in among the oiled wood. In an instant a fierce blaze shot up, as hot, in proportion, as would come from any burning building.

For the second time Tom was about to make a test on a fairly large scale of his experimental extinguisher mixture.

"All ready up there?" he called to his helper perched high in the air.

"All ready!" came back the answer above the roar and crackle of the flames that made Tom and Ned step back.

Would success or failure attend the young inventor's project?



CHAPTER XI

THE BLAZING TREE

Tom Swift hesitated a moment before giving the final word that would send the metal container of powerful chemicals down into the midst of the crackling flames. He wanted to make sure, in his own mind, that he had done everything possible to insure the success of his undertaking. The young inventor never attempted the solution of any problem without going into it with his whole energy. So he wanted this experiment to succeed.

He quickly reviewed, mentally, the composition of the chemical compound. He had made it as strong as possible, and he had spared no pains to insure a hot fire, so that the test would not be too simple.

"What's the matter, Tom?" asked Ned, as his chum appeared to hesitate about giving the word that would send the chemicals hurtling down into the fire.

"Nothing. I was just making sure I hadn't forgotten anything," Tom answered. "I guess I haven't."

He paused a moment, looked up at his assistant on the overhanging arm of the tower, glanced down at the flames, now at their height, and then suddenly cried:

"Let her go!"

"Right!" came back the man's voice, and then a dark object, like a bomb, was seen descending from the skeleton framework above the flames.

There was a scattering of the fire in the pit as the extinguisher bomb fell among the blazing embers. Then followed a slight explosion when the bomb broke, as it was intended it should.

Tom and Ned leaned forward to peer through the pall of smoke which swirled this way and that. Here was to come the real test of the device. Would the fumes of the liberated chemicals choke the fire, or would it burn on in spite of them? That was the question to be settled for Tom Swift.

Almost immediately he had his answer. For after a fierce burst of the tongues of fire following the fall of the bomb, there was a distinct dying down of the conflagration in the pit. Great clouds of smoke arose, but the fire was quenched in a great measure, and as the fire-blanketing gas continued to be generated from the chemicals liberated from the bomb, there was a further dying down of the crackling fire.

"Tom, you've struck it!" yelled Ned in delight. "You have the right combination this time!"

Tom did not answer. He leaned forward and looked eagerly down into the pit. He was about to join with Ned in agreeing that he had, indeed, solved the problem, when, to his surprise, the flames started up again.

"What's this?" asked the young financial manager. "Are you going to have a second test, Tom?"

"Not that I know of," was the puzzled answer. "I don't exactly understand this myself, Ned. By all calculations this fire ought to have died a natural death, but now it is breaking out again. I think what must have happened is that a quantity of the oil they poured on collected in a pool and didn't get all the effects of the chemicals from the bomb. Then the oil started to blaze."

"What can you do about it?" Ned wanted to know.

"Oh, I've got another bomb up there," and Tom pointed to his helper who was still perched on the overhanging arm. "I was prepared for some such emergency as this. Drop the other one!" Tom yelled, and again a dark object fell, bursting in the pit and again liberating the gas that was supposed to choke any fire.

The flames that had started up for the second time instantly died down, and Ned, leaning over the edge of the pit, cried:

"Hurray, Tom! That does the business!" But the young inventor shook his head. "I'm not quite satisfied," he remarked. "It didn't work quickly enough. What I want is a chemical combination that will choke the fire off first shot."

"Well, you pretty nearly have it," observed Ned.

"Yes. But 'good enough' isn't what I want," Tom said. "I've got to work on that chemical compound again. I think I know where I can improve it."

"Well, if I were a fire, and I had this happen to me," remarked Ned, laughing and pointing to the heap of blackened embers in the pit, "I should feel very much discouraged."

"But not enough," declared Tom. "I want the fire to be out more quickly than this one was. I think I can improve that chemical compound, and I'm going to do it."

"All right! Come on down!" he called to his helper, who was still perched on the overhanging arm. "We won't do any more today."

"What is your next move?" asked Ned, as Tom started for his small, private laboratory.

"Oh, I'm going to fiddle around among those sweet-smelling chemicals," answered the young inventor.

"Bless my vest buttons! then I'm not coming in, exclaimed a voice which could proceed from none other than Mr. Damon. And he it proved to be. He had driven over from Waterford in his automobile and had arrived just as the fire test was concluded.

"Oh, come on in!" called Tom. "You can visit with dad, and Eradicate will be glad to see you."

"Poor Rad! How is he?" asked Mr. Damon, walking along with Tom and Ned.

"No change," was the sad answer of the young inventor, for he felt responsible for the mishap to the colored man. "They can't operate on his eyes yet."

"And when they do will he be able to see?" asked Mr. Damon.

"That is what we are all hoping," answered Tom with a sigh. "But do go in to see him, Mr. Damon. It will cheer him up."

"I will," promised the eccentric man. "At any rate I'll not venture near your perfume shop, Tom Swift!"

"And I don't see that I can be of any service," added Ned, "so I'm off to my work."

"All right," assented Tom. "I've got several new schemes to try. Some of them ought to work."

Tom Swift was very busy for the next few days—so busy, in fact, that even Mary saw little of him. He was closeted with Mr. Baxter more than once, and that individual seemed to lose some of his bitter feelings over the loss of his formulae as he found he could be of service to the young inventor. For he was of service in suggesting new ways of combining fire-fighting chemicals, gained by his association with the fireworks concern.

"And that's about all the benefit I derived from being with those scoundrels, Field and Melling," said Mr. Baxter gloomily.

"You still think they took your dye formulae?" asked Tom.

"I'm positive of it, but I can't prove anything. They threatened to get the best of me when I would not sell them, for a ridiculously low sum, an interest in the secrets. And I believe they did get the best of me during that fire."

"I believe the same!" exclaimed Tom.

"How is that? What do you know? Can you help me prove anything against them?" eagerly asked the chemist.

"Well, I don't know," answered Tom slowly. "I'll tell you what I heard."

Thereupon he related the conversation he had overheard while with Mary at the wayside inn. The eyes of Josephus Baxter gleamed as he listened to this recital.

"So that was their game!" he cried, as he smote the table with his fist, thereby nearly upsetting a test tube of acid, which Tom caught just in time. "I knew something crooked was going on, and they thought I'd be so badly overcome in the fire that I wouldn't know, or wouldn't remember, what happened."

"What did happen?" asked Tom. "All I know is that you were overcome in the laboratory room."

"It's too long a story to tell in detail now," said Mr. Baxter. "But the main facts are that through misrepresentations I was induced to associate myself with Field and Melling. They had a good factory for the making of fireworks, and some of the chemicals used in that industry also enter into the manufacture of the kind of dyes I have in mind to make. So I associated myself with them, they agreeing to let me use their laboratory.

"One night they came to see me as I was working there over my formulae. They pretended to have discovered something in an expired patent that nullified what I had. I did not believe this to be so, and I brought out my formulae to compare with theirs—or what they said they had. The next thing I remember was that the fire broke out and my formulae disappeared. Then I was overcome, and I did not care what happened to me, for, having lost the valuable dye formulae, I did not think life worth living.

"Perhaps I was foolish," said Mr. Baxter, "but I had tried so many things and failed, and I counted so much on these formulae that it seemed as if the bottom dropped out of everything when I lost them."

"I know," said Tom sympathetically. "I've been in the same boat myself. But are you sure they took the papers which meant so much to you?"

"I don't see who else could," answered the chemist. "The papers were in a tin box on the table in the room where I was overcome by fire gases, or where, perhaps, they drugged me. I am not clear on this point. And afterward the tin box could not be found. There wasn't enough fire in that room to have melted it."

"No," agreed Tom, "it was mostly smoke in there, and smoke won't melt tin. Nor did I see any box on the table when we carried you out."

"Then the only other surmise is that Field and Melling got away with my formulae during the excitement and when I was half unconscious," Went on Mr. Baxter bitterly. "But you can see how foolish I would be to accuse them in court. I haven't a bit of proof."

"Not much, for a fact," agreed Tom. "Well, with what I heard and what you tell me, perhaps we can work up a case against them later. I'll go over it with Ned. He has a better head for business than I."

"Yes, we inventors need some business brains; or at least the time to give to business problems," agreed the chemist. "But enough of my troubles. Let's get at this chemical compound of yours."

Tom and Mr. Baxter spent many days and nights perfecting the fire-extinguisher chemical, and, after repeated tests, Tom felt that he was nearer his goal.

One afternoon Ned called, and Tom invited him to go for a ride in a small but speedy aeroplane.

"Anything special on?" asked the young manager.

"In a way, yes," Tom answered. "I'm having a firm in Newmarket make me some different containers, and they have promised me samples today. I thought I'd take a fly over and get them. I have the chemical compound all but perfected now, and I want to give it another test."

"All right, I'm with you," assented Ned. "Newmarket," he added musingly. "Isn't that where Field and Melling are now?"

"Yes. They have a factory on the outskirts of the place, and their offices are in the Landmark Building. But we aren't going to see them, though we may call on them later, when you have that case better worked up." For Ned's services had been enlisted to aid Mr. Baxter.

"I shall need a little more time," remarked Ned. "But I think we can at least bluff them into playing into our hands. I have a report to hear from a private detective I have hired."

"I hope we can do something to aid Baxter," remarked Tom. "He has done me good service in this chemical fire extinguisher matter."

A little later Tom and Ned were speeding through the air on their way to Newmarket. The rapid flier was making good time at not a great height when Ned, leaning forward, appeared to be gazing at something in the near distance.

"What's the matter?" asked Tom, for he had his silencer on this craft and it was possible for the occupants to converse. "Do you hear one of the cylinders missing, Ned?"

"No. But what's that smoke down there?" and Ned pointed. "It looks like a fire!"

"It is a fire!" exclaimed Tom, as he took an observation. "Not a big one, but a fire, just the same. If only—"

He did not finish what he started to say, but changed the direction of his air craft and headed directly toward a pall of smoke about a mile away.

In a few seconds they were near enough to make out the character of the blaze.

"Look, Tom!" cried Ned. "It's an immense tree on fire!"

"A tree!" exclaimed Tom, half incredulously, for he was leaning forward to look at one of the aeroplane gages and did not have a clear view of what Ned was looking at.

"Yes, as sure as Mr. Damon would bless something if he were here! It's a tree on fire up near the top!"

"That's strange!" murmured Tom. "But it may give me just the chance I've been looking for."

Ned wondered at this remark on the part of his chum as the airship drew nearer the blazing monarch in the patch of woods over which they were then hovering.



CHAPTER XII

TOM IS LONESOME

"This is certainly the strangest sight I ever saw," remarked Ned, as he and his chum flew nearer and nearer to the smoking and blazing tree. "Is the world turning upside down, Tom, when fires start in this fashion?"

"I fancy it can easily be explained," answered the young inventor. "We'll go into that later. Here, Ned, grab hold of that tin can on the floor and take out the screw plug."

"What's the idea?"

"I want you to drop it as nearly as you can right into the midst of the tree that's on fire."

"Oh, I get your drift! Well, you can count on me."

Ned picked up from the floor of their aeroplane a metal can similar to those Tom used to hold oil or perhaps spare gasoline when he was experimenting on airship speed. The opening was closed with a screw plug, with wings to afford an easier grip. As Ned unscrewed this his nostrils were greeted by an odor that made him gasp.

"Don't mind a little thing like that," cried Tom. "Drop it down, Ned! Drop it down! We're going to be right over the tree in another second or two!"

Ned leaned over the side of the craft and had a good view of the strange sight. The tree that was on fire was a dead oak of great size, dwarfing the other trees in the grove in which it stood. In common with other oaks this one still retained many of its dried leaves, though it was devoid, or almost devoid, of life. Ned noticed in the branches many irregularly shaped objects, and it appeared to be these that were on fire, blazing fiercely.

"It looks as though some one had tied bundles of sticks in the tree and set them on fire," Ned thought as he poised the opened tin of the evil-smelling compound on the edge of the aeroplane's cockpit.

"Let her go, Ned!" cried Tom. "You'll be too late in another second!"

Ned raised himself in his seat and threw, rather than let fall, the can straight for the blazing tree. Like a bomb it shot toward earth, and Ned and Tom, looking down, could see it strike a limb and break open, the rupture of the can letting loose the liquid contained in it.

And then, before the eyes of Tom and Ned, the fire seemed to die out as a picture melts away on a moving picture screen. The smoke rolled away in a ball-like cloud, and the flames ceased to crackle and roar.

"Well, for the love of molasses! what happened, Tom?" cried Ned, as the young inventor guided his craft about in a big circle to come back again over the tree. He wanted to make sure that the fire was out.

It was!

"What sent that blaze to the happy hunting grounds?" asked Ned.

"My new aerial extinguisher," answered Tom, with justifiable pride in his voice. "This fire happened in the nick of time for me, Ned. I had a tin of my new combination in the car, not with any intention of using it, though. I intended to pour it in the new containers I am having made in Newmarket to see if it would corrode them, a thing I wish to avoid.

"But when I saw that tree on fire I couldn't resist the temptation to use my very latest combination of chemicals. It is so recent that I haven't actually tried it on a blaze yet, though I had figured out in theory that it ought to work. And it did, Ned! It worked!"

"Well, I should say so!" agreed his chum. "That blaze was doused for fair. The test could not have been better. But what in the name of a volunteer fire department set that tree to blazing, Tom?"

"I'll tell you in a moment. I want to make some notes before I forget. That combination seems to be just of the right strength. It did the trick. Here, take the wheel and hold her steady while I jot down some memoranda before they get away from me."

Ned was capable of managing an airship, especially under Tom's watchful eye, and as this craft was one with dual controls there was no difficulty in shifting from one steersman to the other.

So while Ned guided, now and then gazing down at the tree from which some smoke still arose, though the fire was all out, Tom made the necessary scientific notes for future amplification.

"And now," observed Ned, as his chum resumed the wheel, "suppose you enlighten me on how that tree came to be on fire—if you didn't set it yourself."

"No, I didn't do that," Tom said, with a laugh. "And I only have a theory as to the cause of the blaze. But suppose we go down and take a look. There's a good field around this grove, and we can get a fine take off. I'll have to go back to Shopton anyhow, to get some more of the chemical."

So the aeroplane made a landing, and then the mystery was explained. The dead oak, to which some of its last year's foliage still clung, was the abiding place of thousands of crows that had built their nests in it. There were hundreds of the big nests, made of dried sticks, mostly, and these made an ideal fuel for the fire.

"But where are the crows, and what started the fire?" asked Ned.

"I fancy the birds flew away as soon as they saw their homes on fire," said Tom. "Or they may not have been at home. Flocks of crows often go to some distant feeding ground for the day, returning at night. I fancy that is what happened here.

"As for the cause of the blaze, I believe it was set by some mischievous boys, who saw a good chance to have some fun without thought of doing any real damage. For the dead tree was of no value, and I imagine the farmers would be glad to see the flock of crows dispersed. Some boys probably climbed up and set fire to one of the nests, and then, when they saw the whole lot going, they became frightened and ran away."

And Tom's theory was, eventually, proved to be true. Some lads, wandering afield, had set fire to the crows' nests and then, frightened as they saw a bigger blaze than they intended, ran away.

Tom and Ned did not remain to see what the returning crows might think about the destruction of their homes, provided they saw fit to return, but, starting the aeroplane, were again on their way.

Tom had lingered long enough to make sure that his latest combination of chemicals had been just what was needed. He felt sure that by using a larger quantity, no fire, however fierce, could continue to blaze.

"But I want to give it a good trial, Ned, as we did from the tower," said Tom. "Though I don't believe there'll be a fizzle this time."

It did not take long for Tom to secure another supply of the new chemical. He then went with it to the firm in Newmarket that was making his containers, or "bombs" as he called them.

On his return he consulted with Mr. Baxter as to the ingredients of the fluid that had put out the blaze in the tree.

"I believe you have at last hit on the right combination," said the chemist. "You are on the road to success, Tom. I wish I could say the same of myself."

"Perhaps your formulae may come back to you as suddenly as they disappeared, or as quickly as I discovered that I had the right thing to put out the fire," said Tom hopefully.

Busy days followed for the young inventor. Now that he was convinced he had at last evolved the right mixture of chemicals, he prepared to make a test on a larger scale than merely a blazing tree.

"I'll try it with a fire in the pit," he said to his chum.

Preparations were made, and the day before Tom was to carry out his plans he received a letter.

"What's the matter? Bad news?" asked Ned, as he saw his friend's face change after reading the epistle.

"Nothing much. Only Mary is going away, and I had expected her to be at the test," Tom answered.

"Going away?" echoed Ned. "For long?"

"Oh, no, only for a couple of weeks. She is going to visit an uncle and aunt in Newmarket, or just outside of that city. Another uncle, Barton Keith, has offices in the Landmark Building, I believe."

"Landmark Building," murmured Ned. "Isn't that where Field and Melling hang out?"

"Yes. But don't mention Mary's uncle in connection with them," laughed Tom. "He wouldn't like it."

"I should say not!"

Ned well remembered Mary's uncle, who had been associated with Tom in recovering the treasure in the undersea search.

"Well, if she can't be here, she can't," said Tom, as philosophically as possible. "I'd better run over and bid her goodbye."

This Tom did, though Ned noticed that his chum acted as though lonesome on his return.

"But when he gets to work testing his new chemical he'll be all right," decided Ned.



CHAPTER XIII

A SUCCESSFUL TEST

"It took you long enough," Ned remarked as Tom entered the main office of the plant, having been to see Mary off on her trip to Newmarket. This was following his call of the night before to learn more particulars of her unexpected visit.

"Yes, I didn't plan to be gone so long," apologized Tom. "But I thought while I was there I might as well go all the way with her."

"And did you?"

"Yes. In the electric runabout. I wanted to come back and get the airship, but she said she wanted to look nice when she met her relatives, and as yet airship travel is a bit mussy. Though when I get my cabined cruiser of the clouds I'll guarantee not to ruffle a curl of the daintiest girl!"

"Getting poetical in your old age!" laughed Ned. "Well, here is that statement you said you wanted me to get ready. Want to go over it now?"

"No, I guess not, as long as you know it's all right. I'm going to start right in and get ready for a bang-up test."

"Of what—your new aerial fire fighting apparatus?"

"Yes. Mr. Baxter and I are going to make up a lot of the chemical compound that—we discovered through using it on the blazing tree—will best do the trick. Then I'm going to try it on a pit fire, and after that on a big blaze with an airship."

"Let me know when you do," begged Ned. "I want to see you do it."

"I'll send you word," promised the young inventor.

Then he began several days and nights of hard work. And he was glad to have the chance to occupy himself, for, though Tom professed not to be much affected by the departure of Mary Nestor, he really was very lonesome.

"How is her uncle, Barton Keith, by the way?" asked Ned, when he called on his chum one day, to find him reading a letter which needed but half an eye to tell was from Mary.

"About as usual," was the answer. "He sends word by Mary that he'll be glad to see us any time we want to call. He has some nice offices in the Landmark Building."

"Those papers proving his right to the oil land, which you recovered from the sunken ship for him, must have made his fortune."

"Well, yes—that and other things," agreed Tom. "Say, we had some exciting times on that undersea search, didn't we?"

"Did you call on Mr. Keith when you went to Newmarket with Mary?" Ned wanted to know, for he and Tom had taken quite a liking to Miss Nestor's uncle.

"No, I didn't get a chance. Besides, I wanted to keep away from the Landmark Building."

"Why?"

"Oh, I might run into Field and Melling, and I don't want to see them until I can accuse them, and prove it, of having taken Mr. Baxter's dye formulae."

"Oh, yes, they're in the same building with Mr. Keith, aren't they? Why do they call it the Landmark? Though I suppose the answer is obvious."

"Yes," assented Tom. "It's a big building—the tallest ever erected in that city, and a fine structure. Though while they were about it I don't see why they didn't make it fireproof."

"Didn't they?" asked Ned, in surprise. "Then the insurance rates must be unusually high, for the companies are beginning to realize how fire departments, even in big cities, are hampered in fighting blazes above the tenth or twelfth stories."

"Yes, it was a mistake not to have the Land mark Building fireproof," admitted Tom. "And Mr. Keith says the owners are beginning to realize that now. It is what is called the 'slow burning' construction."

"Insurance companies don't go much on that," declared Ned, who was in a position to know. "Well, let us hope it never catches fire."

These were busy days for the young inventor. He laid aside all his other activities in order to perfect the plans for manufacturing his new chemical fire extinguisher on a large scale. For Tom realized that while a small quantity of chemicals in a compound might act in a certain way on one occasion, if the bulk should happen to be increased the experimenter could not always count on invariably the same results.

There appeared to be at times a change engendered when a large quantity of chemicals were mixed which was not manifest in a small and experimental batch.

So Tom wanted to mix up a big tank of his new chemical compound and see if it would work in large quantities as well as it did with the small amount Ned had dropped on the blazing tree.

To this end Tom worked at night, as well as by day, and finally he announced to Ned and Mr. Damon, who called one evening, that he believed he had everything in readiness for an exhaustive test the next day.

"There's the stuff!" exclaimed Tom, not a little proudly, as he waved his hand toward an immense carboy in the main shop. "That's what I hope will do the trick. Just take a—"

"Hold on! Stop! That's enough! Bless my hair brush!" cried Mr. Damon, holding up a protesting hand. "If you take that cork out, Tom Swift, you and I will cease to be friends!"

"I wasn't going to open it," laughed the young inventor. "It has a worse odor and seems to choke you more in a big quantity than when there's only a little. I was just going to shake the carboy to let you realize how full it was."

"We'll take your word for it!" laughed Ned. "Now about your test. How are you going to work it?"

"There are to be two tests," answered Tom. "The first, and the smaller, will be in the pit, as before, only this time we shall have what, I believe, will be the successful combination of chemicals to drop on it.

"The second test will be the main one. In that I plan to have an old barn which I have bought set ablaze. Then Ned and I will sail over it in the airship and drop chemicals on it. The barn will be filled with empty boxes and barrels, to make as hot a fire as possible. You are invited to accompany us, Mr. Damon."

"Will there be any smell?" asked the eccentric man, who seemed to have a dislike for anything that was not as agreeable as perfume.

"No, the chemicals will be sealed in containers, which will be dropped from my airship as bombs were dropped in the war," said Tom.

"On those conditions I'll go along," agreed Mr. Damon. "But bless my wedding certificate, Tom! don't tell my wife. She thinks I'm crazy enough now, associating with you and flying occasionally. If she thought I would help you battle with flames from the air she'd likely never speak to me again."

"I'll not tell," promised Tom, laughing.

Preparations for the test went on rapidly. In the morning a fire was to be started in the same pit where the experiment had partly failed before.

From the platform over the blazing hole some of the new combination of chemicals was to be dropped. If it acted with success, as Tom believed it would, he proposed to go on with the more important test in the afternoon.

To this end he had purchased from a farmer the right to set on fire an old ramshackle barn, standing in the midst of a field about three miles outside of Shopton. The barn was on an untilled farm, the house having been destroyed some years before, and it was not near any other structures, so that, even in a high wind, no damage would result.

Tom had filled the barn with inflammable material, and was going to spare no effort to have the test as exhaustive as possible.

The time came for the preliminary trial, and there were a few anxious moments after the oil-soaked boards and boxes in the pit were set ablaze.

"Let her go!" cried Tom to his man on the elevated platform, and down fell the container of chemicals. It had no sooner struck and burst, letting loose a mass of flame-choking vapor, than the fire died out.

"You've struck it, Tom! You've struck it!" cried Ned.

"It begins to look so," agreed the young inventor. "But I'll not call myself out of the woods until this afternoon. Though we can consider it a success so far."

Quite a throng was on hand when the old barn was set ablaze. Tom and Ned and Mr. Damon were there with the airship which had been especially fitted to carry the bombs filled with the extinguisher.

In order to insure a quick, hot blaze the barn was fired on all four sides at once by Tom's men. When it was seen to be a veritable raging furnace of fire, Tom and his two friends took their places in the airship and rapidly mounted upward.

Necessarily they had to circle off away from the blaze to get to the necessary height, but Tom soon brought the airship around again and headed for the black pall of smoke which marked the place of the blazing barn.

"We'll all three send down bombs at the same time," Tom told his friends, as they darted forward. "When I give the word press the levers, and the chemical containers will drop. Then we'll hope for the best."

Higher mounted the flames, and more fiercely raged the fire. The heat of it penetrated even aloft, where Tom and his friends were scudding along in the airship.

"Now!" cried Tom, as his craft hovered for an instant in a favorable position for dropping the bombs. The young inventor, Mr. Damon, and Ned Newton pressed the levers. Looking over the sides of the craft, they saw three dark objects dropping into the midst of the burning barn.



CHAPTER XIV

OUT OF THE CLOUDS

Almost as though some giant hand had dropped an immense cloak over the fire in the barn, so did the blaze die down instantly after Tom Swift's extinguishing liquid had been dropped into the seething caldron of flame. For a moment there was even no smoke, but as the embers remained hot and glowing for a time, though the flames themselves were quenched, a rolling vapor cloud began to ascend shortly after the first cessation of the fire. But this only lasted a little while.

"You've turned the trick, Tom!" cried Ned, leaning far over to look at what was left of the barn and its contents.

"Bless my insurance policy, I should say so!" exclaimed Mr. Damon. "It was certainly neat work, Tom!"

"It does look as if I'd struck the right combination," admitted Tom, and he felt justifiable pride in his achievement.

"Look so! Why, hang it all, man, it is so!" declared Ned. "That fire went out as if sent for by a special delivery telegram to give a hurry-up performance in another locality. Look, there's hardly any smoke even!"

This was so, as the three occupants of the rapidly moving airship could see when Tom circled back to pass again over the almost destroyed structure. He had waited until it was almost consumed before dropping his chemicals, as he wished to make the test hard and conclusive. Now the fire was out except for a few small spots spouting up here and there, away from the center of the blaze.

"Yes, I guess she doesn't need a second dose," observed Tom, when he saw how effective had been his treatment of the fire. "I had an additional batch of chemicals on hand, in case they were needed," he added, and he tapped some unused bombs at his feet.

"I call this a pretty satisfactory test," declared Ned. "If you want to form a stock company, Tom, and put your aerial fire-fighting apparatus on the market, I'll guarantee to underwrite the securities."

"Hardly that yet," said Tom, with a laugh. "Now that I have my chemical combination perfected, or practically so, I've got to rig up an airship that will be especially adapted for fighting fires in sky-scrapers."

"What more do you want than this?" asked Ned, as his chum prepared to descend in the speedy machine.

"I want a little better bomb-releasing device, for one thing. This worked all right. But I want one that is more nearly automatic. Then I am going to put on a searchlight, so I can see where I am heading at night."

"Not your great big one!" cried Ned, recalling the immense electric lantern that had so aided in capturing the Canadian smugglers.

"No. But one patterned after that." Tom answered.

"Bless my candlestick!" exclaimed Mr. Damon, "what do you want with a searchlight at a fire, Tom? Isn't there light enough at a blaze, anyhow?"

"No," answered the young inventor, as he made his usual skillful landing. "You know all the big city fire departments have searchlights now for night work and where there is thick smoke. It may be that some day, in fighting a sky-scraper blaze from the clouds at night, I'll have need of more illumination than comes from the flames themselves."

"Well, you ought to know. You've made a study of it," said Mr. Damon, as he and Ned alighted with Tom, the latter receiving congratulations from a number of his friends, including members of the Shopton fire department who were present to witness the test.

"Mighty clever piece of work, Tom Swift!" declared a deputy chief. "Of course we won't have much use for any such apparatus here in Shopton, as we haven't any big buildings. But in New York, Chicago, Pittsburgh and other cities—why, it will be just what they need, to my way of thinking."

"And he needn't go so far from home," said Mr. Damon. "There is one tall building over in Newmarket—the Landmark. I happen to own a little stock in the corporation that put that up, along with other buildings, and I'm going to have them adopt Tom Swift's aerial fire-fighting apparatus."

"Thank you. But you don't need to go to that trouble," asserted Tom. "My idea isn't to have every sky-scraper equipped with an airship extinguisher."

"No? What then?" asked Mr. Damon.

"Well, I think there ought to be one, or perhaps two, in a big city like New York," Tom answered. "Perhaps one outfit would be enough, for it isn't likely that there would be two big fires in the tall building section at the same time, and an airship could easily cover the distance between two widely separated blazes. But if I can perfect this machine so it will be available for fires out of the reach of apparatus on the ground, I'll be satisfied."

"You'll do it, Tom, don't worry about that!" declared the deputy chief. "I never saw a slicker piece of work than this!"

And that was the verdict of all who had witnessed the performance.

With the successful completion of this exacting test and the knowledge that he had perfected the major part of his aerial fire-extinguisher—the chemical combination—Tom Swift was now able to devote his attention to the "frills" as Ned called them. That is, he could work out a scheme for attaching a searchlight to his airship and make better arrangements for a one-man control in releasing the chemical containers into the heart of a big blaze.

Tom Swift owned several airships, and he finally selected one of not too great size, but very powerful, that would hold three and, if necessary, four persons. This was rebuilt to enable a considerable quantity of the fire-extinguishing liquid to be stored in the under part of the somewhat limited cockpit.

This much done, and while his men were making up a quantity of the extinguisher, using the secret formula, and storing it in suitable containers, Tom began attaching a searchlight to his "cloud fire-engine," as Koku called it.

The giant was aching to be with Tom and help in the new work, but Koku was faithful to the blinded Eradicate, and remained almost constantly with the old colored man.

It was touching to see the two together, the giant trying, in his kind, but imperfect way, to anticipate the wishes of the other, with whom he had so often disputed and quarreled in days past. Now all that was forgotten, and Koku gave up being with Tom to wait on Eradicate.

While the colored man was, in fact, unable to see, following the accident when Tom was experimenting with the fire extinguisher, it was hoped that sight might be restored to one eye after an operation. This operation had to be postponed until the eyes and wounds in the face were sufficiently healed.

Meanwhile Rad suffered as patiently as possible, and Koku shared his loneliness in the sick room. Tom came to see Rad as often as he could, and did everything possible to make his aged servant's lot happier. But Rad wanted to be up and about, and it was pathetic to hear him ask about the little tasks he had been wont to perform in the past.

Rad was delighted to hear of Tom's success with the new apparatus, after having been told how quickly the barn fire was put out.

"Yo'—yo' jest wait twell I gits up, Massa Tom," said Rad. "Den Ah'll help make all de contraptions on de airship."

"All right, Rad, there'll be plenty for you to do when the time comes," said the inventor. And he could not help a feeling of sadness as he left the colored man's room.

"I wonder if he is doomed to be blind the rest of his life," thought Tom. "I hope not, for if he does it will be my fault for letting him try to mix those chemicals."

But, hoping for the best, Tom plunged into the work ahead of him. He did not want to offer his aerial fire extinguisher to any large city until he had perfected it, and he was now laboring to that end.

One day, in midsummer, after weary days of toil, Tom took Ned out for a ride in the machine which had been fitted up to carry a large supply of the chemical mixture, a small but powerful searchlight, and other new "wrinkles" as Tom called them, not going into details.

"Any special object in view?" asked Ned, as Tom headed across country. "Are you going to put out any more tree fires?"

"No, I haven't that in mind," was the answer. "Though of course if we come across a blaze, except a brush fire, I may put it out. I have the bombs here," and Tom indicated the releasing lever.

"What I want to try now is the stability of this with all I have on board," he resumed. "If she is able to travel along, and behave as well as she did before I made the changes, I'll know she is going to be all right. I don't expect to put out any fires this trip."

In testing the ship of the air Tom sent her up to a good height, heading out over the open country and toward a lake on the shores of which were a number of summer resorts. It was now the middle of the season, and many campers, cottagers and hotel folk were scattered about the wooded shore of the pretty and attractive body of water.

Tom and Ned had a glimpse of the lake, dotted with many motor boats and other craft, as the airship ascended until it was above the clouds. Then, for a time, nothing could be seen by the occupants but masses of feathery vapor.

"She's working all right," decided Tom, when he found that he could perform his usual aerial feats with his craft, laden as she was with apparatus, as well as he had been able to do before she was so burdened. "Guess we might as well go down, Ned. There isn't much more to do, as far as I can see."

Down out of the heights they swept at a rapid pace. A few moments later they had burst through the film of clouds and once more the lake was below them in clear view.

Suddenly Ned pointed to something on the water and cried:

"Look, Tom! Look! A motor boat in some kind of trouble! She's sinking!"



CHAPTER XV

COALS OF FIRE

Tom Swift saw the craft almost as soon as did his chum. It was rather a large-sized motor boat, quite some distance out from shore, and there was no other craft near it at this time. From the quick, first view Tom and Ned had of it, they decided that a party of excursionists were on a pleasure trip.

But that an accident had happened, and that trouble, if not, indeed, danger, was imminent, was at once apparent to the young inventor and the other occupant of the swiftly moving airship.

For as Tom shut off his motor, to volplane down, thus reducing all noise on his craft, they could dimly hear the shouts and calls for help, coming from the water craft below them.

"Help! Help!" came the impassioned appeals, floating up to Tom and Ned.

"We're coming!" Tom answered, though it is doubtful if his voice was heard. Sound does not seem to carry downward as well as upward, and though Tom's craft was making scarcely any noise, save that caused by the rush of wind through the struts and wires, there was so much confusion on the motor boat, to say nothing of the engine which was going, that Tom's encouraging call must have been unheard.

"What are you going to do, Tom?" asked Ned, "You can't land on the water!"

"I know it; worse luck! If I only had the hydroplane, now, we could make a thrilling rescue—land right beside the other boat and take 'em all off. But, as it is, I'll have to land as near as I can and then we will look for a boat to go out to them in."

Ned saw, now, what Tom's object was. On one shore of the lake was a large, level field, suitable for a landing place for the craft of the air. At least it looked to be a suitable place, but Tom would be obliged to take a chance on that. This field sloped down to the beach of the lake, and as Ned and his chum came nearer to earth they could see several boats on shore, though no persons were near them. Had there been, probably they would have gone to the rescue.

Tom cast a rapid look across the sheet of water, to make sure his services were really needed. The motor boat was lower in the lake now, and was, undoubtedly, sinking. And no other craft was near enough to render help. Though distant whistles, seeming to come from approaching craft, told of help on the way.

"Hold fast, Ned!" cried Tom, as they neared the earth. "We may bump!"

But Tom Swift was too skillful a pilot to cause his craft to sustain much of a crash. He made an almost perfect "three point landing," and there would have been no unusual shaking, except for the fact that the field was a bit bumpy, and the craft more heavily laden than usual.

"Good work, Tom!" cried Ned, as the Lucifer slackened her speed, the young inventor having sent her around in a half circle so that she now faced the lake. Then Tom and Ned climbed from the cockpit, throwing off goggles and helmets as they ran to the shore where there were several rowboats moored.

"And a little old-fashioned naphtha launch! By all that's lucky!" cried Tom. "I didn't think they made these any more. If she only works now!"

There was a little dock at this point on the lake, and the boats appeared to be held at it for hire. But no one was in charge, and Tom and Ned made free with what they found. They considered they had this right in the emergency.

The naphtha launch was chained and padlocked to the dock, but using an oar Tom burst the chain.

"Get one of the rowboats and fasten it to the back of the launch!" Tom directed Ned. "I don't believe this craft will hold them all," and he nodded toward those aboard the sinking boat—for it was only too plainly sinking now.

"All right!" voiced Ned. "I'm with you. Can you get that engine to work?"

"She's humming now," announced Tom, as he turned on the naphtha, and threw in a blazing match to ignite it, this act saving his hand. Naphtha engines are a trifle treacherous.

A few moments later, though not as quickly as a gasoline craft could have been gotten under way, Tom was steering the small launch out and away from the dock, and toward the craft whence came the faint calls for help. Behind them Tom and Ned towed a large rowboat.

Tom speeded the naphtha craft to its limit, and, fortunately for those in danger, it was a fast boat. In less time than they had thought possible, the young inventor and his chum were near the boat that was now low in the water—so low, in fact, that her rail was all but awash.

"Oh, take us out! Save us!" screamed some of the girls.

"Take it easy now," advised Tom, approaching with care. "We've got room for you all. Ned, get back in the rowboat and bring that alongside—on the other side. We'll take you all in," he added.

"Girls first!" called Ned sternly, as he saw one young fellow about to scramble into the naphtha boat.

"Sure, girls first!" agreed the skipper of the disabled craft. "Hit a submerged log," he explained to Tom, as the work of rescue proceeded. "Stove a hole in the bow, but we stuffed coats and things in, and made it a slow leak. Kept the engine going as long as we could, but I thought no one would ever come! Lucky you happened to see us from up there!"

"Yes," assented Tom shortly. He and Ned were too busy to talk much, as they were aiding in getting some hysterical girls and young women into the two sound craft. And when the last of the picnic party had been taken off, the boat with a hole in it gave a sudden lurch, there was a gurgling, bubbling sound, and she sank quickly.

Tom and Ned had anticipated this, however, and had their craft well out of the way of the suction.

"You'll all have to sit quiet," Tom warned his passengers as he took Ned's boat, with her load, in tow. "I've got about all the law allows me to carry," he added grimly.

"Oh, what ever would we have done without you?" half sobbed one girl.

"I guess you could have managed to swim ashore," Tom answered, not wanting to make too much of his effort.

Then more rescue boats came up, but those in the naphtha craft, and Ned's smaller one, refused to be transferred, and remained with our friends until safely landed at the dock.

Receiving the half-hysterical thanks of the party, and leaving them to explain matters to the owner of the borrowed boats, Ned and Tom went back to the Lucifer, and were soon aloft again.

"Pretty slick act, Tom," remarked Ned.

"Oh, it's all in the day's work," was the answer. He had all but perfected his big fire-extinguishing aeroplane, and was contemplating means by which he could give a demonstration to the fire department of some big city, when Mr. Baxter asked to see Tom one day. There was a look on the face of the chemist that caused Tom to exclaim with a good deal of concern:

"What's the matter?"

"Only the same old trouble," was the discouraged answer. "I can't get on the track of my lost secret formulae. If I had Field and Melling here now I—I'd—"

He did not finish his threat, but the look on his face was enough to show his righteous anger.

"I wish we could do something to those fellows!" exclaimed Tom energetically. "If we only had some direct evidence against them!"

"I've got evidence enough—in my own mind!" declared Mr. Baxter.

"Unfortunately that doesn't do in law," returned Tom. "But now that I have this airship firefighter craft so nearly finished, I can devote more time to your troubles, Mr. Baxter."

"Oh, I don't want you bothered over my troubles," said the chemist. "You have enough of your own. But I'm at my wit's end what to do next."

"If it is money matters," began Tom.

"It's partly that, yes," said the other, in a low voice. "If I had those dye formulae, I'd be a rich man."

"Well, let me help you temporarily," begged Tom. And the upshot of the talk was that he engaged Mr. Baxter to do certain research work in the Swift laboratories until such time as the chemist could perfect certain other inventions on which he was working.

In return for his kindness to a fellow laborer, Tom received from Mr. Baxter some valuable hints about fire-extinguishing chemicals, one hint, alone, serving to bring about a curious situation.

It was several days after the accident to the motor boat from which the young inventor and Ned Newton had rescued the party of pleasure seekers that Tom was visited by Mr. Damon, who drove over in his car.

"Have you anything special to do, Tom?" asked the eccentric man. "If you haven't I wish you'd take a ride with me. Not for mere pleasure! Bless my excursion ticket, don't think that, Tom!" cried his friend quickly.

"I know better than to ask you out for a pleasure jaunt. But I have become interested in a certain candy-making machine that a man over in Newmarket is anxious to sell me a share in, and I'd like to get your opinion. Can you run over?"

"Yes," Tom answered. "As it happens I am going to Newmarket myself."

"Oh, I forgot about Mary Nestor being there!" laughed Mr. Damon. "Sly dog, Tom! Sly dog!" and he nudged the youth in the ribs.

"It isn't altogether Mary. Though I am going to see her," Tom admitted. "It has to do with a little apparatus I am getting up. I can capture several birds in the same auto, so I'll go along."

This pleased Mr. Damon, and he and Tom were soon speeding over the road. It was just outside Newmarket that they saw an automobile stalled at the foot of a hill which they topped. It needed but a glance to show that there was serious trouble. As Mr. Damon's car went down the slope two men could be seen leaping from the other machine. And, as they did so, flames burst out of the rear of the stalled machine.

"Fire! Fire!" cried Mr. Damon, rather needlessly it would seem, as any one could see the blaze.

"Another chance!" exclaimed Tom, reaching down between his feet for a wrapped object he had placed in Mr. Damon's car. "It's Field and Melling!" he cried. "The two men who boasted of having put it over on Mr. Baxter. Their car is blazing. Here's where I get a chance to heap coals of fire on their heads!"



CHAPTER XVI

VIOLENT THREATS

Tom Swift's companion in the automobile was sufficiently acquainted with this old expression to understand readily what it meant. And as he directed his car as close as was safe to the blazing car, Mr. Damon asked:

"Are you going to put out that fire for them, Tom?"

"I'm going to try," was the grim answer.

The young inventor was rapidly taking out of wrapping paper a metal cylinder with a short nozzle on one end and a handle on the other. It was, obviously, a hand fire extinguisher of a type familiar to all.

"Wait Tom, I'll slow up a little more," said Mr. Damon, as he applied the brakes with more force. "Bless my court plaster! don't jump and injure yourself."

But Tom Swift was sufficiently agile to leap from the automobile when it was still making good speed. He did not want Mr. Damon to approach too close to the burning car, for there might be an explosion. At the same time, he rather discounted the risk to himself, for he ran right in, while the two men, who had leaped from the blazing machine, hurried to a safe distance.

Tom held in readiness a small hand extinguisher. It was one he had constructed from an old one found in the shop, but it contained some of his own chemicals, the original solution having been used at some time or other. It was the intention of the young inventor to put on the market a house-size extinguisher after he had disposed of his big airship invention.

"Look out there! The gasoline tank may go up!" cried Field, the small man with the big voice.

Tom did not answer, but ran in as close as was necessary and began to play a small stream from his hand extinguisher on the blazing car. He was thus able to direct the white, frothy chemical better than when he had shot it from the airship, and in a few seconds only some wisps of curling smoke remained to tell of the presence of the fire. The automobile was badly charred, but the damage was not past redemption.

"Bless my check book! you did the trick, Tom," cried Mr. Damon, as he alighted and came up to congratulate his companion.

"Yes. But this wasn't much," Tom said. "I didn't use half the charge. Short circuit?" he asked Field and Melling who were now returning, having seen that the danger was passed.

"I—I guess so," replied Melling, in his squeaky voice. "We—we are much obliged to you."

"No thanks necessary," said Tom, a bit shortly, as he turned to go back with Mr. Damon to their car. "It's what any one would do under like circumstances."

"Only you did it very effectively," observed Field.

Tom was wondering if they knew who he was and of his association with Josephus Baxter. He did not believe the men recognized him as the person who had been at the Meadow Inn one day with Mary. They had hardly glanced at him then, he thought.

"That's a mighty powerful extinguisher you have there, young man," said Melling. "May I ask the make of it? We ought to carry one like it on our car," he told his companion.

"It is the Swift Aerial Fire Extinguisher," said Tom gravely, with a glance at Mr. Damon.

"The Swift—Tom Swift?" exclaimed Melling. "Do you mean—"

"I am Tom Swift," put in the young inventor quickly. "And this is one of my inventions. I might add," he said slowly, looking first Melling and then Field full in the face, "that I was aided in perfecting the chemical extinguisher by Josephus Baxter."

The effect on the two men, whom Tom believed were scoundrels, was marked.

"Baxter!" cried Field.

"Is he associated with you?" demanded Melling.

"Not officially," Tom answered, delighted at the chance to "rub it in," as he expressed it later. "I have been helping him, and he has been helping me since he lost his dye formulae in—in your fire!"

"Does he say he lost them in the fire of our factory?" demanded Field aggressively.

"He believes he did," asserted Tom. "I helped carry him out of the laboratory of your place when he was almost dead from suffocation. He remembers that he had the formulae then, but since has been unable to find them."

"He'd better be careful how he accuses us!" blustered Field, in his big voice.

"We could have the law on him for that!" squeaked the bigger Melling.

"He hasn't accused you," said Tom easily. "He only says the formulae disappeared during the fire in your place, and he is just wondering, that is all—just wondering!"

"Well, he—we, I—that is, we haven't anything from Baxter that we didn't pay for," declared Field. "And if he goes about saying such things he'd better be careful. I am going—"

But he suddenly became silent as his companion's elbow nudged him. And then Melling took up the talk, saying:

"We're much obliged to you, Mr. Swift, for putting out the fire in our car. But for you it would have been destroyed. And if you ever want to sell the extinguisher process of yours, you'll find us in the market. We are going into the dye business on a large scale, and we can always use new chemical combinations."

"My extinguisher is not for sale," said Tom dryly. "Come on, Mr. Damon. We can take you into town, I suppose," Tom went on, looking at his eccentric friend for confirmation, and finding it in a nod. "But I doubt if we could tow you, as we are in a hurry, and—"

"Oh, thank you, we'll look over our machine before we leave it," said Melling. "It may be that we can get it to go."

Tom doubted this, after a look at the charred section, but he easily understood the dislike of the men, upon whose heads he had heaped coals of fire, to ride with him and Mr. Damon.

So Field and Melling were left standing in the road near their stranded car, which, but for Tom Swift's prompt action, would have been only a heap of ruins.

Tom first visited the man who had a candy machine, in which the owner wanted to interest Mr. Damon. After seeing a demonstration and giving his opinion, he attended to his own affairs, in which his hand extinguisher played a part. Then he called on Mary Nestor at her relative's home.

"Oh, but it's good to see you again, Tom!" cried Mary, after the first greeting. "What have you been doing, and what's all that white stuff on your coat?"

"Fire extinguisher chemical," Tom answered, and he related what had happened.

"What's the matter with your aunt, Mary? She seems worried about something," he said, after the aunt with whom Mary was staying had come in, greeted Tom briefly, and gone out again.

"Oh, she and Uncle Jasper are worried over money matters, I believe," Mary said. "Uncle Jasper invested heavily in the Landmark Building here, and now, I understand, it is discovered that it was put up in violation of the building laws—something about not being fire-proof. Uncle Jasper is likely to lose considerable money.

"It isn't that it will make him so very poor," Mary went on. "But Uncle Barton Keith—you remember you went on the undersea search with him—Uncle Barton warned Uncle Jasper not to go into the Landmark Building scheme."

"And Uncle Jasper did, I take it," said Tom.

"Yes. And now he's sorry, for not only may he lose money, but Uncle Barton will laugh at him, and Uncle Jasper hates that worse than losing a lot. But tell me about yourself, Tom. What have you been doing? And is Eradicate going to get better?"

"I hope so," Tom said. "As for me—"

But he was interrupted by loud voices in the hall. He recognized the tones of Mary's Uncle Jasper saying:

"They're scoundrels, that's what they are! Just plain scoundrels! When I accuse them of swindling me and others in that Landmark Building deal they have the nerve to ask me to invest money in some secret dye formulae they claim will revolutionize the industry! Bah! They're scoundrels, that's what they are—Field and Melling are scoundrels, and I'm going to have them arrested!"



CHAPTER XVII

A TOWN BLAZE

Mary's uncle, Jasper Blake, always an impetuous man, opened the door so quickly that Tom, who was standing near it talking to Mary, barely had time to move aside.

"Oh, Tom, excuse me! Didn't see you!" bruskly went on Mr. Blake. "But this thing has gotten on my nerves and I guess I'm a bit wrought up.

"There isn't any guessing about it, Uncle Jasper," said Mary, with a laugh and a look at Tom to warn him not to tell her relative that he had just befriended Field and Melling. "For," as Mary said to Tom later, "he would positively rave at you."

Tom was wise enough to realize this, and so, after some laughing reference to the effect that he would have to wear protective armor if he stood near doors when Mary's uncle opened them so suddenly, the conversation became general.

"I hope you never get roped in as I have been," said Mr. Blake, as he sat down. "Those scoundrels, Field and Melling, would rob a baby of his first tooth if they had the chance!"

"No, I am not likely to have anything to do with them; though I have met them," and Tom gave Mary a glance. "But did I hear you say they are embarking on a dye enterprise?" he asked. "I couldn't help overhearing what you said in the hall," he explained.

"That's the story they tell," said Uncle Jasper. "I was foolish enough to invest in the Landmark Building, and now I'm likely to lose it all in a lawsuit."

"I mentioned it," said Mary.

"And that isn't the worst," went on Mr. Blake. "But Barton—that's your friend of the submarine—will give me the laugh, for he was asked to invest in the same building, and didn't."

"Oh, maybe it will all turn out right," said Tom consolingly. "My friend Mr. Damon has a little stock in the same structure."

"Nothing those two scoundrels have anything to do with will turn out right," declared Mary's uncle. "And to think of their nerve when they ask me to go in with them on a dye scheme!"

"That's what interests me," said Tom.

"Well, take my advice and don't become interested to the extent of investing any money," warned Mr. Blake. "I'm not going to."

"I didn't mean that way," said Tom. "But I happen to be acquainted with an expert dye maker who lost some secret formulae during a fire in Field and Melling's factory."

"You don't say so!" cried Mr. Blake. "Tom Swift, there's something wrong here! Let you and me talk this over. I begin to see how I may be able to take a peep through the hole in the grindstone," a colloquial expression which was as well understood by Tom as were some of Mr. Damon's blessing remarks.

"If you're going to talk business I think I'll excuse myself," said Mary.

"Don't go," urged Tom, but she said to him that she would see him before he left, and then she went out, leaving her uncle and the young inventor busily engaged in talking.

But though Mr. Blake had certain suspicions regarding Field and Melling, and though Tom Swift, too, believed they had something to do with the disappearance of Baxter's secret formulae, it was another matter to prove anything.

Impetuous as he often was, Mr. Blake was for calling in the police at once, and having the two men arrested. But Tom counseled delay.

"Wait until we get more evidence against them," he urged.

"But they may skip out!" objected Mary's uncle.

"They won't with that Landmark Building on their hands," said the young inventor.

"Their hands! Huh! They'll take precious good care that the trouble and responsibility of it are on other people's hands before they go," declared Mr. Blake. "However, I suppose you're right. Barton Keith sets a deal by your opinion since that undersea search, and while I don't always agree with him, I do in this case. Especially since he is likely to have the laugh on me."

"Oh, I wouldn't count everything lost in that building deal," said Tom. "A way may be found out of the trouble yet. But I must be getting back. Dr. Henderson was to give a report today on the condition of Eradicate's eyes, and I want to be there."

"Mary was saying something about your faithful old retainer being in trouble," said Mr. Blake. "I'm sorry to hear about it."

"We are all sorry for poor Rad," replied Tom slowly. "I only hope he gets his sight back. His last days will be very sad if he doesn't."

Tom found Mary waiting for him after he had left her uncle, and, after a short talk with her, he made ready to ride back with Mr. Damon, who, after having attended to several other matters, was now outside in his car.

"When are you coming home, Mary?" Tom asked.

"In a week or two," she answered. "I'll send word when I'm ready and you can come and get me."

"Delighted!" declared Tom. "Don't forget!" During the ride home the young inventor was unusually silent, so much so that Mr. Damon finally exclaimed:

"Bless my phonograph, Tom Swift! but what is the matter? Has Mary broken the engagement?"

"Oh, no, nothing like that," was the answer. "Only I'm wondering about Eradicate, and—other matters."

Other matters had to do with what Mary's uncle had told Tom about the interest manifested by Field and Melling in some dye industry.

Tom's forebodings regarding his colored helper were nearly borne out, for Dr. Henderson gloomily shook his head when asked for the verdict.

"It's too early to say for a certainty," replied the medical man, "but I am not as hopeful as I was, Tom, I'm sorry to say."

"I'm sorry to hear it," returned Tom. "Is there anything we can do—any hospital to which we can send him for special treatment?"

"No, he is doing as well as he can be expected to right here. Besides, he has his friends around him, and the companionship of that giant of yours, absurd as it may seem, is really a tonic to Eradicate. I never saw such devotion on the part of any one."

"Koku has certainly changed," said Tom. "He and Rad used always to be quarreling. But I guess that is all over," and Tom sighed.

"Oh, I wouldn't say that," declared the medical man. "I haven't given up, though there are some symptoms I do not like. However, I am going to wait a week and then make another test."

Tom knew that the week would be an anxious one for him, but, as it developed, he had so much to do in the next few days that, for the time being, he rather forgot about Eradicate.

Field and Melling, he heard incidentally, had their machine towed to a garage for repairs, but beyond that no word came from the two men. Josephus Baxter remained at work over his dye formulae in one of Tom's laboratories, but the young inventor did not see much of the discouraged old man.

Tom did not tell of the encounter with Field and Melling and of extinguishing the fire in their car, for he knew it would only excite Mr. Baxter, and do no good.

It was within a few days of the time when Tom was to call in a committee of fire insurance experts to give them a demonstration of the efficiency of his aerial fire-fighting machine. He was putting the finishing touches to his craft and its extinguishing-dropping devices when he received a call from Mr. Baxter.

"Well, how goes it?" asked Tom, trying to infuse some cheer into his voice.

"Not very well," was the answer. "I've tried, in every way I know, to get on the track of the missing methods perfected by that Frenchman, but I can't. I'd be a millionaire now, if I had that dye information."

"Do you really think they have them—actually have the formulae?" asked Tom.

"I certainly do. And the reason I believe so is that I was over at a chemical supply factory the other day when an order came in for a quantity of a very rare chemical."

"What has that to do with it?" asked Tom.

"This chemical is an ingredient called for by one of the dye formulae that were stolen from me. I never heard of its being used for anything else. I at once became suspicious. I learned that this chemical had been ordered sent to Field and Melling in their new offices in the Landmark Building."

"Maybe they intend to use it in making a new kind of fireworks," suggested Tom.

Mr. Baxter shook his head.

"That chemical never would work in a skyrocket or Roman candle," he said. "I'm sure they're trying to cheat me out of my dye formulae. If I could only prove it!"

"That's the trouble," agreed Tom. "But I'll give you all the help I can. And, come to think of it, I believe you might interest Mr. Blake. He has no love for Field and Melling, and he has several keen lawyers on his staff. I believe it would be a good thing for you to talk to Mr. Blake."

"Please give me a letter of introduction to him," begged Mr. Baxter. "What I need is legal talent and capital to fight these scoundrels. Mr. Blake may supply both."

"He may," agreed Tom. "I'll fix it so you can meet him. But what do you think of this combination, Mr. Baxter? It is my very latest solution for putting out fires. I'm loading an airship up with some of the bomb containers now, and—"

Tom's further remarks were interrupted by the noise of shouting and tumult in the street, and a moment later yells could be heard of:

"Fire! Fire! Fire!"

"Another blaze!" exclaimed Mr. Baxter, raising the shades which had been drawn, since night had fallen.

"And not far away," said Tom, as he caught the reflection of a red gleam in the sky.

There was a ring at the front doorbell, and almost at once Ned Newton's voice called:

"Tom! Tom Swift! There's quite a fire in town! Don't you want to try your new apparatus on it?"

"The very chance!" exclaimed the young inventor. "Come on, Mr. Baxter. There's room in the airship for you and Ned. I want you to see how my chemical works!"

Without waiting for a reply from the chemist, Tom caught him by the hand and led him toward the side door that gave egress to the yard where one of the airships was housed. Tom caught sight of Ned, who was hastening toward him.

"Big fire, Tom!" said the young manager again. "Fierce one!"

"I'm going to try to put it out!" Tom answered. "Want to come?"

"Sure thing!" answered Ned.



CHAPTER XVIII

FINISHING TOUCHES

Tom Swift and Ned Newton were so accustomed to acting quickly and in emergencies that it did not take them long to run out the airship, which Tom had in readiness, not especially for this emergency, but to demonstrate his new apparatus to a committee of fire underwriters whom he had invited to call in a few days.

"Take this, if you will, Mr. Baxter!" cried Tom, giving the chemist a metal container. "It's a little different combination from the extinguisher I already have in the machine. Maybe I'll get a chance to try it."

"You're going to have all the chance you want, Tom, by the looks of that blaze," commented Ned Newton.

"It does look like quite a fire," observed Tom, as he gazed up at the sky, where the reflection was turning to a brighter red.

Outside in the streets near the Swift house and shops could be heard the rattle of fire apparatus, the patter of running feet, and many shouts from excited men and boys.

"Any idea what it is, Ned?" asked Tom, as he motioned to Mr. Baxter to climb into the aircraft.

"Some one said it was the new Normal School. But that's farther to the north," was Ned's answer. "By the way the blaze has increased since I first saw it, I'd take it to be the lumberyard."

"That would make a monster blaze!" observed Tom. "I don't believe I'll have chemicals enough for that," and he looked at the rather small supply in his craft. "However, I haven't time to get any more. Besides, they'll have the regular department on the job, and this isn't a skyscraper, anyhow."

"No, we'll have to go to New York or Newmarket for one of those," observed Ned. "All ready, Tom?"

"All ready," said the young inventor, as Ned took his place beside Mr. Baxter.

"What's the matter, Tom?" asked the voice of Mr. Swift, as he came out into the yard, having been attracted by the flashing lights and the noise of the aircraft motor, as Tom gave it a preliminary test.

"There's a fire in town," Tom answered. "I'm going to see if they need my services."

"Guess there isn't any question about that," said his business manager.

Tom's father, who was suffering the infirmities of age, was in the habit of retiring early, and he had dozed off in his chair directly after supper, to be awakened by the shouting and confusion about the place.

"Take care of yourself, my boy!" he advised, as there came a moment of silence before the throttle of the aircraft was opened to send it on its upward journey. "Don't take too many risks."

"I won't," Tom promised. "We'll be back soon."

Then came the roar of the motor as Tom cut out the muffler to gain speed and, a moment later, he and his two friends were sailing aloft with a load of fire-extinguishing chemicals.

Up and up rose the aircraft. It was not the first time Mr. Baxter had enjoyed the sensation, but he was not enough of a veteran to be immune to the thrills nor to be altogether void of fear. And it was his first night trip. Still he gave few evidences of nervousness.

"These she is!" cried Ned, for when the exhaust from the motor was sent through the new muffler Tom had attached it was possible to talk aboard the Lucifer. The young manager pointed down toward the earth, over which the craft was then skimming, though at no great height.

"It is the lumberyard!" exclaimed Mr. Baxter presently.

"It sure is," assented Tom. "I know I haven't enough stuff to cover as big a blaze as that, but I'll do my best. Fortunately there is no wind to speak of," he added, as he guided the craft in the direction of the fire.

"What has that to do with it—I mean as far as the working of your chemical extinguisher is concerned?" asked Mr. Baxter. "Can't you drop the bomb containers accurately in a wind?"

"Well, the wind has to be allowed for in dropping anything from an aeroplane," Tom answered. "And, naturally, it does spoil your aim to an extent. But the reason I'm glad there is no wind to speak of is that the chemical blanket I hope to spread over the fire won't be so quickly blown away."

"Oh, I see," said Mr. Baxter. "Well, I'm glad that you will be able to have a successful test of your invention."

"The regular land apparatus is on hand," observed Ned, for they were now so near the fire that they could look down and, in the reflection from the blaze, could see engines, hose-wagons and hook and ladder trucks arriving and deploying to different places of advantage, from which to fight the lumberyard fire that was now a roaring furnace of flames.

"No skyscraper work needed here," observed Tom. "But it will give me a chance to use the latest combination I worked out. I'll try that first. Are you ready with it, Mr. Baxter?"

"Yes," was the answer.

The young inventor, not heeding the cries of wonder that arose from below and paying no attention to the uplifted hands and arms pointing to him, steered his craft to a corner of the yard where there was a small isolated fire in a pile of boards. It was Tom's idea to try his new chemical first on this spot to watch the effect. Then he would turn loose all his other containers of the chemical mixture that had proved so effective in other tests.

Attention of those who had gathered to look at the fire was about evenly divided between the efforts of the regular department and the pending action by Tom Swift. The latter was not long in turning loose his latest sensation.

"Let it go!" he cried to Mr. Baxter, and down into the seething caldron of flame dropped a thin sheet-iron container of powerful chemicals. Leaning over the cockpit of the aircraft, the occupants watched the effect. There was a slight explosion heard, even above the roar of the flames, and the tongues of fire in the section where Tom's extinguisher had fallen died down.

"Good work!" cried Ned.

"No!" answered Tom, shaking his head. "I was a little afraid of this. Not enough carbon dioxide in this mixture. I'll stick to the one I found most effective." For the flames, after momentarily dying down, burst out again in the spot where he had dropped the bomb.

Tom wheeled the airship in a sharp, banking turn, and headed for the heart of the fire in the lumberyard. It was clearly getting beyond the control of the regular department.

"How about you, Ned?" called Tom, for he had given his chum charge of dropping the regular bombs containing a large quantity of the extinguisher Tom had practically adopted.

"All ready," was the answer.

"Let 'em go!" came the command, and down shot the dark, spherical objects. They burst as they hit the ground or the piles of blazing lumber, and at once the powerful gases generated by the mixture of several different chemicals were released.

Again the three in the airship leaned eagerly over the side of the cockpit to watch the effect. It was almost magical in its action.

The bombs had been dropped into the very fiercest heart of the fire, and it was only an instant before their action was made manifest.

"This will do the trick!" cried Ned. "I'm certain it will."

"I didn't have much fear that it wouldn't," said Tom. "But I hoped the other would be better, for it is a much cheaper mixture to make, and that will count when you come to sell it to big cities."

"But the fire is certainly dying down," declared Mr. Baxter.

And this was true. As container after container of the bomb type fell in different parts of the burning lumberyard, while Tom coursed above it, the flames began to be smothered in various sections.

And from the watching crowds, as well as from the hard-working members of the Shopton fire department, came cheers of delight and encouragement as they saw the work of Tom Swift's aerial fire-fighting machine.

For he had, most completely, subdued what threatened to be a great fire, and when the last of his bombs had been dropped, so effective was the blanket of fire-dampening gases spread around that the flames just naturally expired, as it were.

As Tom had said, the absence of wind was in his favor, for the generated gases remained just where they were wanted, directly over the fire like an extinguishing blanket, and were not blown aside as would otherwise have been the case.

And, by the peculiar manner in which his chemicals were mixed, Tom had made them practically harmless for human beings to breathe. Though the fire-killing gases were unpleasant, there was no danger to life in them, and while several of the firemen made wry faces, and one or two were slightly ill from being too close to the chemicals, no one was seriously inconvenienced.

"Well, I. guess that's all," said Tom, when the final bomb had been dropped. "That was the last of them, wasn't it, Ned?"

"Yes, but you don't need any more. The fire's out—or what isn't can be easily handled by the hose lines."

"Good!" cried Tom. "But, all the same, I wish I had been able to make the first mixture work."

"Perhaps I can help you with that," suggested Mr. Baxter.

And the following day, after Tom had received the thanks of the town officials and of the fire department for his work in subduing the lumberyard blaze, the young inventor called Josephus Baxter in consultation.

"I feel that I need your help," said the young inventor. "You have been at this chemical study longer than I, and I am willing to pay you well for your work. Of course I can't make up to you the loss of your dye formulae. But while you are waiting for something to turn up in regard to them, you may be glad to assist me."

"I will, and without pay," said the chemist.

But Tom would not hear of that, and together he and Mr. Baxter set about putting the finishing touches to Tom's latest invention.



CHAPTER XIX

ON THE TRAIL

"There, Tom Swift, it ought to work now!"

Josephus Baxter held up a large laboratory test tube, in which seethed and bubbled some strange mixture, turning from green to purple, then to red, and next to a white, milky mixture.

"Do you think you've hit on the right combination?" asked the young inventor, whose latest idea, the plan of fighting fires in skyscrapers from an airship as a vantage point, was taking up all his spare moments.

"I'm positive of it," said Mr. Baxter. "I've dabbled in chemicals long enough to be certain of this, even if I can't get on the track of the missing dye formulae."

"That certainly is too bad," declared Tom. "I wish I could help you as much as you have helped me."

"Oh, you have helped me a lot," said the chemist. "You have given me a place to work, much better than the laboratory I had in the old fireworks factory of Field and Melling. And you have paid me, more than liberally, for what little I have done for you."

"You've done a lot for me," declared Tom. "If it had not been for your help this chemical compound would not be nearly as satisfactory as it is, nor as cheap to manufacture, which is a big item."

"Oh, you were on the right track," said Mr. Baxter. "You would have stumbled on it yourself in a short time, I believe. But I will say, Tom Swift, that, between us, we have made a compound that is absolutely fatal to fires. Even a small quantity of it, dropped in the heart of a large blaze, will stop combustion."

"And that's what I want," declared Tom. "I think I shall go ahead now, and proceed with the manufacture of the stuff on a large scale."

"And what do you propose doing with it?" asked Mr. Baxter.

"I'm going to sell the patent and the idea that goes with it to as many large cities as I can," Tom answered. "I'll even manufacture the airships that are needed to carry the stuff over the tops of blazing skyscrapers, dropping it down. I'll supply complete aerial fire-fighting plants."

"And I think you'll do a good business," said the chemist.

It was the conclusion of the final tests of an improved chemical mixture, and the reaction that had taken place in the test tube was the end of the experiment. Success was now again on the side of Tom Swift.

But when that has been said there remains the fact that it was just the other way with the unfortunate Mr. Baxter.

Try as he had, he could not succeed in getting the right chemical combination to perfect the dye process imparted to him by his late French friend. With the disappearance of the secret formulae went the good luck of Josephus Baxter.

He had worked hard, taking advantage of Tom's generosity, to bring back to his memory the proper manner of mixing certain ingredients, so that permanent dyes of wondrous beauty in coloring would be evolved. But it was all in vain.

"I know who have those formulae," declared the chemist again and again. "It is those scoundrels, Field and Melling. And they are planning to build up their own dye business with what is mine by right!"

And though Tom, also, believed this, there was no way of proving it.

As the young inventor had said, he was now ready to put his own latest invention on the market. After many tests, aided in some by Mr. Baxter, a form of liquid fire extinguisher had been made that was superior to any known, and much cheaper to manufacture. Veteran members of fire departments in and about Shopton told Tom so. All that remained was to demonstrate that it would be as effective on a large scale as it was on a small one, and big cities, it was agreed, must, of necessity, add it to their equipment.

"Well, I think I'll give orders to start the works going," said Tom, at the conclusion of the final test. "I have all the ingredients on hand now, and all that remains is to combine them. My airship is all ready, with the bomb-dropping device."

"And I wish you all sorts of luck," said Mr. Baxter. "Now I am going to have another go at my troubles. I have just thought of a possible new way of combining two of the chemicals I need to use. It may be I shall have success."

"I hope so," murmured Tom. He was about to leave the room when Koku, the giant, entered, with a letter in his hand. The big man showed some signs of agitation, and Tom was at once apprehensive about Eradicate.

"Is Rad—has anything happened—shall I get the doctor?"

"Oh, Rad, him all right," answered Koku. "That is him not see yet, but mebby soon. Only I have to chase boy, an' he make faces at me—boy bring this," and the giant held out the envelope.

"Oh!" exclaimed Tom, and he understood now. Messenger boys frequently came to Tom's house or to the shops, and they took delight in poking fun at Koku on account of his size, which made him slow in getting about. The boys delighted to have him chase them, and something like this had evidently just taken place, accounting for Koku's agitation.

"This is for you, Mr. Baxter, not for me," said Tom, as he read the name on the envelope.

"For me!" exclaimed the chemist. "Who could be writing to me? It's a big firm of dye manufacturers," he went on, as he caught a glimpse of the superscription in the upper left hand corner.

Quickly he read the contents of the epistle, and a moment later he gave a joyful cry.

"I'm on the trail! On the trail of those scoundrels at last!" exclaimed Josephus Baxter. "This gives me just the evidence I needed! Now I'll have them where I want them!"



CHAPTER XX

A HEAVY LOAD

Josephus Baxter was so excited by the receipt of the letter which Koku delivered to him that for some seconds Tom Swift could get nothing out of him except the statement:

"I'm on their trail! Now I'm on their trail!"

"What do you mean?" Tom insisted. "Whose trail? What's it all about?"

"It's about Field and Melling! That's who it's about!" exclaimed Mr. Baxter, with a smothered exclamation. "Look, Tom Swift, this letter is addressed to me from one of the biggest dye firms in the world—a firm that is always looking for something new!"

"But if you haven't anything new to give them, of what use is it?" Tom asked, for he knew that the chemist had said his process, stolen, as he claimed, by Field and Melling, was his only new project.

"But I will have something new when I get those secret formulae away from those scoundrels!" declared Mr. Baxter.

"Yes, but how are you going to do it, when you can't even prove that they have them?" asked Tom.

"Ah, that's the point! Now I think I can prove it," declared Mr. Baxter. "Look, Tom Swift! This letter is addressed to me in care of Field and Melling at the office I used to have in their fireworks factory."

"The office from which you were rescued nearly dead," Tom added.

"Exactly. The place where you saved me from a terrible death. Well, if you will notice, this letter was written only two days ago. And it is the first mail I have received as having been forwarded from that address since the fire. I know other mail must have come for me, though."

"What became of it?" asked Tom.

"Those scoundrels confiscated it!" declared the chemist. "But, in some manner, perhaps through the error of a new clerk, this letter was remailed to me here, and now I have it. It is of the utmost importance!"

"In what way?" asked Tom.

"Why, it is directed to me, outside and in, and it makes an inquiry about the very dyes of the lost secret formulae, one dye in particular."

"I don't quite understand yet," said Tom.

"Well, it's this way," went on Mr. Baxter. "I had, in the office of Field and Melling, all the papers telling exactly how to make the dyes. After the fire, in which I was rendered unconscious, those papers disappeared.

"The only way in which any one could make the dyes in question was by following the formulae given in those papers. And now here is a letter, addressed to me from a big firm, asking my prices on a certain dye, which can only be made by the process bequeathed to me by the Frenchman."

"Which means what?" asked Tom.

"It means that Field and Melling must have been writing to this firm on their own hook, offering to sell them some of this dye. But, in some way, my name must have appeared on the letter or papers sent on by the scoundrels, and this big firm replies to me direct, instead of to Field and Melling! Even then I would not have benefited if they had confiscated this letter as I am sure, they have done in the case of others. But, by some slip, I get this.

"And it proves, Tom Swift, that Field and Melling are in possession of my dye formulae, and that they have tried to dispose of some of the dye to this firm. Not knowing anything of this, the firm replies to me. So now I have direct evidence—just what I wanted—and I can get on the trail of the scoundrels who have cheated me of my rights."

Tom looked at the letter which, it appeared, had been left with Koku by a special delivery boy from the post office. It was an inquiry about certain dyes, and was addressed to Mr. Baxter in care of Field and Melling, the former fireworks firm, which now had started a big dye plant, with offices in the Landmark Building in Newmarket.

"It does look as though you might get at them through this," Tom said, as he handed back the letter. "But I'm afraid you'll have to get further evidence before you could convict them in a court of law—you'll have to show that they actually have possession of your formulae."

"That's what I wish I could do," said the chemist, somewhat wistfully. His first enthusiasm had been lessened.

"I'll help you all I can," offered Tom. And events were soon to transpire by which the young inventor was to render help to the chemist in a most sensational manner.

"Just now," Tom went on, "I must arrange about getting a large supply of these chemicals made, and then plan for a test in some big city."

"Yes, you have done enough for me," said Mr. Baxter. "But I think now, with this letter as evidence, we'll be able to make a start."

"I agree with you," Tom said. "Why don't you go over to see Mr. Damon? He's a good business man, and perhaps he can advise you. You might also call on that lawyer who does work for Mr. Keith and Mr. Blake. And that reminds me I must call Mary Nestor up and find out when she is coming home. I promised to fetch her in one of the airships."

"I will go and see Mr. Damon," decided Mr. Baxter. "He always gives good advice."

"Even if he does bless everything he sees!" laughed Tom. "But if you're going to see him I'll run you over. I'm going to Waterfield."

"Thanks, I'll be glad to go with you," said the chemist.

Mr. Damon was glad to see his friends, and, when he had listened to the latest developments, he exclaimed with unusual emphasis:

"Bless my law books, Mr. Baxter! but I do believe you're on the right trail at last. Come in, and we'll talk this over."

So Tom left them, traveling on to a distant city where he arranged for a large supply of the chemicals he would need in his extinguisher.

For several days Tom was so busy that he had little time to devote to Mr. Baxter, or even to see him. He learned, however, that the chemist and Mr. Damon were in frequent consultation, and the young inventor hoped something would come of it.

Tom's own plans were going well. He had let several large cities know that he had something new in the way of a fire-fighting machine, and he received several offers to demonstrate it.