there was no indication that they were prisoners the next day, however. third sarge elfor and the other officers were cordial at breakfast and lunch, although they caught some quizzical glances directed at them from time to time. their movements were not hampered. they were given the run of the town.

after noon their armored car was brought in, hauled by four teams of horses. flanked by a troop of soldiers, it was pulled around a corner and vanished from their sight.

"if they're so curious about how it runs, why aren't they quizzing us instead of letting us go on a sight-seeing tour?" wondered ann, staring after the disappearing vehicle.

"i've built up a theory on these earthmen...." began phil. but he was interrupted as an officer and a squad of soldiers approached them. the officer saluted smartly.

"deev john gray, third sarge elfor sends greetings and desires that you confer with him. the others will be free to continue their inspection of the military city of pebbro."

"very well," agreed john. "ann, you'd better come along with me to take notes on the conference. we'll see you two tonight, if not sooner."

he motioned to the officer to lead the way, and the group went up the street, leaving phil and fran standing in the shadow of a towering building.

"what's your theory, phil?" asked fran.

"simple," he answered. "the jovian war wiped out civilization. they've just climbed back up part of the way, but they still don't know how to operate the machinery and use the power they have available."

"i don't know about that," said fran doubtfully. "they seem to know how to handle those cannon and searchlights at the spaceport all right."

"automatic control, probably, or—" phil paused. he was peering through a barred window at street level. "say, fran, look here! unless i miss my guess, this is a central power station!"

fran stooped to look.

"i think you're right," she said. "but it's deserted."

"proof of my theory," he said triumphantly. "now, if we can just find a door somewhere...."