ded with a
tremendous report.

A most remarkable thing followed, sending the occupants of the room
rushing for the staircase, the women uttering cries of alarm. Bob
staggered backwards and sat down heavily on the floor. His experiment
had been attended with greater success than he had even dreamed were
possible. It had been followed by a terrific crash. A cloud of dust
filled the room, the structure vibrated as if from a slight earthquake
shock, then quiet once more settled over the gloomy attic of
Treasureholme.

CHAPTER XV

AN AMAZING OCCURRENCE

BOB was on his feet again ere the dust had settled in the room.

"Don't be alarmed," he cried. "There is no danger so long as you keep
away from that partition. That is where the trouble lies."

"Where--where is the hammer?" cried Grace.

Stevens stepped forward and looked for the maul on the floor near the
baseboard, but finally glanced up with a perplexed expression in his
eyes.

"The maul has disappeared, too," he said.

There was a gasp following this announcement. But the young man was not
disturbed.

"I understand a little of what all this means," he said. "The maul has
gone. If someone will get me an axe I will chop down this partition near
where I struck it with the maul."

"Is there some secret there?" whispered Mr. Presby over Bob's shoulder.
The young man nodded.

"Yes. I have an idea what it is. However, we shall see."

When the axe was brought he chose his location with some care, then
began chopping away, swinging the axe in a manner that showed him to be
no novice at that sort of work. The axe went through the partition soon
after that. Using the back of the tool, he began smashing in the boards,
here and there employing the blade to cut through a scantling or a
brace. Soon after he had laid open a dark recess behind the partition.

Tom pushed forward and was about to crawl in when the young man stopped
him.

"Better be careful, young man! That may be a pitfall, and I suspect that
it is."

The others were too amazed to speak. Still another secret in the old
house had been revealed. But the sudden disappearance of the maul was
still unexplained, though Stevens had his own idea about this. He began
cutting further. A tremendous crash followed a moment of chopping. He
sprang back to await developments. There were none.

"There, I think I have drawn the monster's teeth," he said, reaching for
a lantern. "One of you will please hold a