"Now I'm going to see what made that shaft fall," said Tom to
Ned, as the two chums walked over to the bench where the young
inventor had been working. "The tap I gave it never ought to have
brought it down."

Together they examined the thin, but strong, cords that had
been passed around the shaft, having been fastened to two nails,
driven into the wall.

"Look!" cried Tom, pointing to one of the cords.

"What is it?" asked Ned.

"The strands were partly cut through, so that only a little jar
was enough to break the remaining ones," went on Tom. "They've
been cut with a knife, too, and not frayed by vibration against
the nail, as might be the case. Ned, someone has been in my shop,
meddling, and he wanted this shaft to fall. This is a trick!"

"Great Scott, Tom! You don't suppose any one wanted that shaft
to fall on you; do you?"

"No, I don't believe that. Probably some one wanted to damage
the shaft, or he might have thought it would topple over against
the bench, and break some of my tools, instruments or machinery.
I do delicate experiments here, and it wouldn't take much of a
blow to spoil them. That's why those cords were cut."

"Who did it? Do you think Andy Foger--"