Koku managed to make Tom understand that the dye inventor was in the main office of the Swift plant talking to Tom's father. The young inventor sent Mary home in his electric runabout in company with Ned Newton, who, fortunately, happened along just then, and hurried to his office.
"Oh, Tom, I'm glad you have arrived," said his father. "You remember Mr. Baxter, of course."
"I should hope so," Tom answered, extending his hand. He noticed that the man whom he had helped save from the fireworks blaze was under the stress of some excitement.
"I hope he hasn't been getting on dad's nerves," thought Tom, as he took a seat. The elder Mr. Swift had been quite ill, and it was thought for a time that he would have to give up helping Tom. But there had been a turn for the better, and the aged inventor had again taken his place in the laboratory, though he was frail.
"What's the trouble now?" asked Tom. "At least I assume there has been some trouble," he went on. "If I am wrong—"
"No, you are right, unfortunately," said Mr. Baxter gloomily. "The trouble is that everything I do is a failure. Up to a little while ago I thought I might succeed, in spite of Field and Melling's theft of the formulae from me. I made a purple dye the other day, and tested it today. It was a miserable failure, and it got on my nerves. I came to see if you could help me."
"In what way?" asked Tom, wondering whether or not he had best tell Mr. Baxter what he had overheard at the Inn.
"Well, I need better laboratory facilities," the man went on. "I know you have been very kind to me, Mr. Swift, and it seems like an imposition to ask for more. But I need a different lot of chemicals, and they cost money. I also need some different apparatus. You have it in your big laboratory. That wouldn't cost you anything. But of course to go out and buy what I need—"
"Oh I guess we can stand that, can't we, Dad?" asked Tom, with a genial smile. "You may have free access to our big laboratory, Mr. Baxter, and I'll see that you get what chemicals you need."
"Oh, thank you!" exclaimed the inventor. "Now I believe I shall succeed in spite of those rascals. Just think, Mr. Swift! They have started a big new dye factory."
"So I have heard," replied Tom.
"And I'm almost sure they're using the secret formulae they stole from me!" exclaimed Mr. Baxter. "But I'll get the best of them yet! I'll invent a better dye than they ever can, even if they use the secrets the old Frenchman gave me. All I need is a better place to work and all the chemicals at my disposal."
"Then we'll try to help you," offered Tom.
"And if I can do anything let me know," put in Mr. Swift. "I shall be glad to get in the harness again, Tom!" he added.
"Well, if you're so anxious to work, Dad, why not give me a hand with my fire extinguisher chemical?" asked Tom. "I haven't been able to hit on the solution, somehow or other."
"Perhaps I may be able to give you a hint or two after I get settled down," suggested Mr. Baxter.
"I shall be glad of any assistance you can give," replied Tom Swift. "And now I'm going to start right in. Dad, you can make the arrangements for Mr. Baxter to use our big laboratory. And let him have credit for any chemicals he needs. Have them put on my bill, for I am buying a lot myself."
"I'll never forget this," said Mr. Baxter, and there were tears in his eyes as he shook hands with Tom, who tried to make light of his generous act.
Tom, after the wrecking of his laboratory, in which accident poor Eradicate was injured, had built himself another—two others, in fact, after having shared Mr. Baxter's temporary one for a time. Tom put up the most completely equipped laboratory that could be devised, and he also erected a smaller one for his own personal use, the main one being at the disposal of his father and the various heads of the different departments of the Shopton plant.
The little conference broke up, and Tom was on his way to his own special private laboratory when there came the sound of some excitement in the corridor outside and Mr. Damon burst in.
"Bless my accident policy, Tom! what's this I hear?" he asked, all in a fluster.
"I'm sure I don't know," answered the young inventor, with a smile. "What about?"
"About you and Mary Nestor being killed!" burst out Mr. Damon. "I heard you fell in the aeroplane and were both dashed to pieces!"
"If you can believe the evidence of your own eyes, I'm far from being in that state," laughed Tom. "And as for Mary, she just left here with Ned Newton."
"Thank goodness!" sighed Mr. Damon, sinking into a chair. "Bless my elevator! I rushed over as soon as I heard the news, and I was almost afraid to come in. I'm so glad it didn't happen!"
"No gladder than I," said Tom. "We had to make a forced landing, that was all," and he made as light of the incident as possible when he saw the look of terror in his father's eyes.
"Some people in Waterford saw you going down," went on Mr. Damon, "and they told me."
"It was a false alarm," replied Tom. "And now, Mr. Damon, if you want to smell some perfumes come with me."
"Are you going into that line, Tom?" asked the eccentric man. "Bless my handkerchief, my wife will be glad of that!"
"I mean I'm going to experiment some more with fire-extinguishing chemicals," laughed the young inventor. "If you want to—"
"Bless my gas mask, I should say not!" cried Mr. Damon. "I don't see how you stand those odors, Tom Swift."
"Guess I'm used to 'em," was the answer. And then, leaving his father to entertain Mr. Damon and to make arrangements for Mr. Baxter's use of the main laboratory, he betook himself to his own private quarters.
The next week or so was a busy time for Tom; so busy, in fact, that he had little chance to see Mr. Baxter. All he knew was that the unfortunate man was also laboring in his own line, and Tom wished him success. He knew that if the man made any discoveries that would help with the fire-extinguishing fluid he would report, as he had promised.
"Well, Tom, how goes it?" asked Ned one day when he came over to call on his chum. "Are you ready to accept contracts for putting out skyscraper blazes in all big cities?"
"Not yet," was the answer. "But I'm going to make another attempt, Ned."
"You mean another experiment?"
"Yes, I have evolved a new combination of chemicals, using something of the carbonate idea as a basis. I found that I couldn't get away from that, much as I wanted to. But my application is entirely new, at least I hope it will prove so."
"When are you going to try it?" asked Ned.
"Right away. All I have to do is to put the chemicals in the metal tank."
"Then I'd better get my leather suit on," remarked Ned, starting to take off his street coat. Tom kept for his chum a full outfit of flying garments, one suit being electrically heated.
"Oh, we aren't going up in any airship," Tom said.
"Why, I thought you were going to test your aerial fire fighting dingus!" exclaimed Ned.
"So I am. But I want to stay on the ground and watch the effect on the blaze as the tank bursts and scatters the chemical fluid."
"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?
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.
"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.
"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 Landmark 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.