red shed all right; I'm sure of that."

"Do you really mean it?" cried Ned.

"I sure do."

"Well, if that's the case, I wouldn't leave such dangerous things
around where there are explosives, Tom."

"I didn't, Ned. I wouldn't have had this within a hundred miles of my
shed, if I could have had my way. It's a fire bomb, and it was set to
go off at a certain time. Only I think something went wrong, and the
bomb started a fire ahead of time.

"If it had worked at night, when we were all asleep, we might not have
put the fire out so easily. This sure is suspicious! I'm glad you found
this, Koku."

Tom was carefully examining the bomb, as Ned had correctly named it.
The bank clerk, now that he was assured by his chum that the object had
done all the harm it could, approached closer.

What he saw was merely a hollow shell of iron, with a small opening in
it, as though intended for a place through which to put a charge of
explosives and a fuse.

"But there was no explosion, Tom," explained Ned.

"I know it," said Tom quietly. "It wasn't an explosive bomb. Smell
that!"

He held the object under Ned's nose so suddenly that the young bank
clerk jumped back.

"Oh, don't get nervous," laughed Tom. "It can't hurt you now. But what
does that smell like?"

Ned sniffed, sniffed again, thought for a moment, and then sniffed a
third time.

"Why," he said slowly, "I don't just know the name of it, but it's that
funny stuff you mix up sometimes to put in the oxygen tanks when we go
up in the rarefied atmosphere in the balloon or airship."

"Manganese and potash," spoke Tom. "That and two or three other things
that form a chemical combination which goes off by itself of
spontaneous combustion after a certain time. Only the person who put
this bomb together didn't get the chemical mixture just right, and it
went off ahead of time; for which we have to be duly thankful."

"Do you really think that, Tom?" cried Ned.

"I'm positive of it," was the quiet answer.

"Why--why--that would mean some one tried to set fire to the red shed,
Tom!"

"They not only tried it, but did it," responded Tom, more coolly than
seemed natural under the circumstances. "Only for the fact that the
mixture went off before it was intended to, and found us all alert and
ready--well, I don't like to think what might have happened," and Tom
cast a look about at his group of buildings with their valuable
contents.

"You mean some one purposely p