High up aloft, over the blazing red shed, with its dangerous contents that any moment might explode, Tom Swift continued to hold his big dirigible balloon as near the flames as possible. And as he stood outside on the small deck in front of the pilot-house, where were located the various controls, the young inventor pulled the levers that emptied bag after bag of fine sand on the spouting flames that, already, were beginning to die down as a result of this effectual quenching.

"Tom's done the trick!" yelled Ned, paying little attention now to the big airship shed, since he saw that the danger was about over.

"Dhat's what he suah hab done!" agreed Eradicate. "Mah ole mule Boomerang couldn't 'a' done any better."

"Huh! Your mule afraid of fire," remarked Koku.

"What's dat? Mah mule afraid ob fire?" cried the colored man. "Look heah, yo' great, big, overgrowed specimen ob an equilateral quadruped, I'll hab yo' all understand dat when yo' all speaks dat way about a friend ob mine dat yo'--"

"That'll do, Rad!" broke in Ned, with a laugh. He knew that when Tom's helper grew excited on the subject of his mule there was no Stopping him, and Boomerang was a point on which Eradicate and Koku were always arguing. "The fire is under control now."

"Yes, it seems to have gone visiting," observed Koku.

"Visiting?" queried Ned, in some surprise.

"Yes, that is, it is going out," went on Koku.

"Oh, I understand!" laughed Ned. "Yes, and I hope it doesn't pay us another visit soon. Oh, look at Tom, would you!" he cried, for the young aviator had swung his ship about over the flames, to bring another row of sand bags directly above a place where the fire was hottest.

Down showered more sand from the bags which Tom opened. No fire could long continue to blaze under that treatment. The supply of air was cut off, and without that no fire can exist. Water would have been worse than useless, because of the carbide, but the sand covered it up so that it was made perfectly harmless.

Moving slowly, the airship hovered over every part of the now slowly expiring flames, the burned opening in the roof of the shed making it possible for the sand to reach the spots where it was most needed. The flames died out in section after section, until no more could be seen--only clouds of black smoke.

"How is it now?" came Tom's voice, as he spoke from the deck of the balloon through a megaphone.

"Almost out," answered Mr. Damon. "A little more sand, Tom."

The eccentric man had caught up a piece of paper and, rolling it into a cone, made an improvised megaphone of that.

"Haven't much more sand left," was Tom's comment, as he sent down a last shower. "That will have to do. Hustle that carbide and other explosive stuff out of there now, while you have a chance."

"That's it!" cried Ned, who caught his chums meaning. "Come on, Koku. There's work for you."

"Me like work," answered the giant, stretching out his great arms.

The last of the sand had completely smothered the fire, and Tom, observing from aloft that his work was well done, moved away in the dirigible, sending it to a landing space some little distance away from the shed whence it had arisen. It was impossible to drop it back again through the roof of the hangar, as the balloon was of such bulk that even a little breeze would deflect it so that it could not be accurately anchored. But Tom had it under very good control, and soon it was being held down on the ground by some of his helpers.

As all the sand ballast had been allowed to run out Tom was obliged to open the gas-valves and let some of the lifting vapor escape, or he could not have descended.

"Come on, now!" cried the inventor, as he leaped from the deck of his sky craft. "Let's clean out the red shed. That fire is only smothered, and there may be sparks smoldering under that sand, which will burst into flame, if we're not careful. Let's get the explosives out of the way.

"Bless my insurance policy, yes," exclaimed Mr. Damon. "That was a fine move of yours."

"It was the only way I could think of to put out the fire," Tom replied. "I knew water was out of the question, and sand was the next thing."

"But I didn't know where to get any until I happened to think of the ballast bags of my dirigible. Then I knew, if I could get above the fire, I could do the trick. I had to fly pretty high, though, as the fire was hot, and I was afraid it might explode the gas bag and wreck me."

"You were taking a chance," remarked Ned.

"Oh, well, you have to take chances in this business," observed Tom, with a smile. "Now, then, let's finish this work."

The sand, falling from the ballast bags of the dirigible, had so effectually quenched the fire that it was soon cool enough to permit close approach. Koku, Tom and some of the men who best knew how to handle the explosives, were soon engaged in the work of salvage.

"I wish I could help you, Tom," said his aged father. "I don't seem able to do anything but stand here and look on," and he gazed about him rather sadly.

"Never you mind, Dad!" Tom exclaimed. "We'll get along all right now. You'd better go up to the house. Mr. Damon will go with you.

"Yes, of course!" exclaimed the odd man, catching a wink from Tom, who wanted his father not to get too excited on account of his weak heart. "Come along, Professor Swift. The danger is all over."

"All right," assented the aged inventor, with a look at the still smoking shed.

"And, Dad, when you haven't anything else to do," went on Tom, rather whimsically, "you might be thinking up some plan to take up the recoil of those guns on my aerial warship. I confess I'm clean stumped on that point."

"Your aerial warship will never be a success," declared Mr. Swift. "You might as well give that up, Tom."

"Don't you believe it, Dad!" cried Tom, with more of a jolly air of one chum toward another than as though the talk was between father and son. "You solve the recoil problem for me, and I'll take care of the rest, and make the air warship sail. But we've got something else to do just now. Lively, boys."

While Mr. Swift, taking Mr. Damon's arm, walked toward the house, Tom, Ned, Koku, and some of the workmen began carrying out the explosives which had so narrowly escaped the fire. With long hooks the men pulled the shed apart, where the side walls had partly been burned through. Tom maintained an efficient firefighting force at his works, and the men had the proper tools with which to work.

Soon large openings were made on three sides of the red shed, or rather, what was left of it, and through these the dangerous chemicals and carbide, in sheet-iron cans, were carried out to a place of safety. In a little while nothing remained but a heap of hot sand, some charred embers and certain material that had been burned.

"Much loss, Tom?" asked Ned, as they surveyed the ruins. They were both black and grimy, tired and dirty, but there was a great sense of satisfaction.

"Well, yes, there's more lost than I like to think of," answered Tom slowly, "but it would have been a heap sight worse if the stuff had gone up. Still, I can replace what I've lost, except a few models I kept in this place. I really oughtn't to have stored them here, but since I've been working on my new aerial warship I have sort of let other matters slide. I intended to make the red shed nothing but a storehouse for explosive chemicals, but I still had some of my plans and models in it when it caught."

"Only for the sand the whole place might have gone," said Ned in a low voice.

"Yes. It's lucky I had plenty of ballast aboard the dirigible. You see, I've been running it alone lately, and I had to take on plenty of sand to make up for the weight of the several passengers I usually carry. So I had plenty of stuff to shower down on the fire. I wonder how it started, anyhow? I must investigate this."

"Mr. Damon and Eradicate seem to have seen it first," remarked Ned.

"Yes. At least they gave the alarm. Guess I'll ask Eradicate how he happened to notice. Oh, I say, Rad!" Tom called to the colored man.

"Yais, sah, Massa Tom! I'se comin'!" the darky cried, as he finished piling up, at a safe distance from the fire, a number of cans of carbide.

"How'd you happen to see the red shed ablaze?" Tom asked.

"Why, it was jest dish yeah way, Massa Tom," began the colored man. "I had jest been feedin' mah mule, Boomerang. He were pow'ful hungry, Boomerang were, an', when I give him some oats, wif a carrot sliced up in 'em--no, hole on--did I gib him a carrot t'day, or was it yist'day?--I done fo'got. No, it were yist'day I done gib him de carrot, I 'member now, 'case--"

"Oh, never mind the carrot, or Boomerang, either, Rad!" broke in Tom, "I'm asking you about the fire."

"An' I'se tellin' yo', Massa Tom," declared Eradicate, with a rather reproachful look at his master. "But I wanted t' do it right an' proper. I were comin' from Boomerang's stable, an' I see suffin' red spoutin' up at one corner ob de red shed. I knowed it were fire right away, an' I yelled."

"Yes, I heard you yell," Tom said. "But what I wanted to know is, did you see anyone near the red shed at the time?"

"No, Massa Tom, I done didn't."

"I wonder if Mr. Damon did? I must ask him," went on the young inventor. "Come, on, Ned, we'll go up to the house. Everything is all right here, I think. Whew! But that was some excitement. And I didn't show you my aerial warship after all! Nor have you settled that recoil problem for me."

"Time enough, I guess," responded Ned. "You sure did have a lucky escape, Tom."

"That's right. Well, Koku, what is it?" for the giant had approached, holding out something in his hand.

"Koku found this in red shed," went on the giant, holding out a round, blackened object. "Maybe him powder; go bang-bang!"

"Oh, you think it's something explosive, eh?" asked Tom, as he took the object from the giant.

"Koku no think much," was the answer. "Him look funny."

Tom did not speak for a moment. Then he cried:

"Look funny! I should say it did! See here, Ned, if this isn't suspicious I'll eat my hat!" and Tom beckoned excitedly to his chum, who had walked on a little in advance.