"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 wouldn't do the things he's done, unless he's got a rocket-blasting good reason!"
Roger quickly added, "And he wouldn't try to buck Captain Strong unless he was playing for high stakes!"
"Right," said Tom. "The only thing that could have caused our watches to go haywire, like the ships instruments, would be uranium. Lots of uranium. And uranium is the only thing valuable enough to make Vidac take such long chances."
"But how can you tell it's uranium?" asked Logan.
"Our watches are not ordinary timepieces, sir," explained Tom. "They are specially constructed for use in space travel. Each watch is electrically controlled and highly sensitive."
"Electric?" repeated Logan in amazement. "Electric wrist watches? That small thing?"
Tom smiled. "Each is charged by a miniature power pack, sir."
"The uranium deposits out in the hills affected these watches," continued Astro, "the same way they affected the electronic instruments on the spaceships coming in to Roald."