Roger."

"You probably forgot to wind it," said Tom. He glanced casually at his
own watch and suddenly exclaimed. "Say, my watch has three-thirty!"

"And mine says four twenty-two!" cried Astro.

Roger and Tom looked at each other, eyes widening.

"You don't think--?" began Tom, hardly daring to breathe.

"Yes, I do!" said Roger. "Remember what happened to the instruments?"

[Illustration]

"Uranium!" exclaimed Astro.

The word echoed in the kitchen like the blast of a bomb. The boys looked
at each other, too startled to explain to Logan and Jane, who, though
they were listening intently, were unable to fathom the boys' reasoning.

"Where were you last night?" asked Jeff quickly.

Roger described as nearly as he could remember the exact route that they
had traveled in making their way to the Logan farm.

"Hey, I think I've got the answer, fellows!" Tom suddenly exclaimed.
"If Vidac came out here last night and took over Mr. Logan's farm, and
we're falsely accused of getting rid of the professor, and the professor
is missing, there must be something to tie it all together. Vidac