Swift were running away. Yet Ned knew his chum
better than that.

Then, as they watched, Ned and the others saw the direction of the
balloon change. She turned around in response to the influence of the
rudders and propellers, and was headed straight for the blazing shed,
but some distance above it.

"What can he be planning?" wondered Ned.

He did not have long to wait to find out.

An instant later Tom's plan was made clear to his chum. He saw Tom
circling over the burning red shed, and then the bank clerk saw what
looked like fine rain dropping from the lower part of the balloon
straight into the flames.

"He can't be dousing water on from up above there," reasoned Ned.
"Pouring water on carbide from a height is just as bad as spurting it
on from a hose, though perhaps not so dangerous to the persons doing
it. But it can't be--"

"By Jove!" suddenly exclaimed Ned, as he had a better view of what was
going on. "It's sand, that's what it is! Tom is giving battle to the
flames with sand from the ballast bags of the dirigible! Hurray? That's
the ticket! Sand! The only thing safe to use in case of an explosive
chemical fire.

"Fine for you. Tom Swift! Fine!"

CHAPTER IV

SUSPICIONS

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. "Th