"That would be just a little kitchen blower. Not big enough--we need a
man-sized one."

Ken said, after a long pause, "There isn't one in town. The chances of
getting one from somewhere else are practically zero. Frederick is 50
miles away and by tomorrow there may not be a car in town that would go
that far."

"Look," said Al, "how about the air-conditioning systems in town? There
isn't one that's any good where it is, now. Both the high school and the
college have big ones. I'll bet we could get permission at either place
to revamp the intake and outlet ducts so we could put in our filters and
precipitators. Your father and his friends could swing it for us at the
college."

"You might be right! It's worth trying. For precipitators we can rig a
battery-powered system that will put a few thousand volts on the
screens. Art will let us have enough car batteries for that. I think
we're set!"

* * * * *

Dave Whitaker did not return until dusk, but he had succeeded in getting
the horse and wagon, and a load of hay. He deposited this in his own
yard before driving back to Ken's place.

During the next two or three hours the boys found two old motorcycle
engines, a power lawn-mower motor, and one old gasoline-powered washing
machine. All of these they took down to Art Matthews' place and begged
him for space and tools to overhaul the equipment.

"You can have the whole joint," Art said dejectedly. "This pile of junk
will never move!" He waved a hand at the cars lined up and down both
sides of the streets near his place.

By 9 o'clock they had succeeded in getting all of the small engines
running, but they dared not test them too long, hoping to conserve all
possible life that might be left. When they were through, they returned
to Ken's house. Mrs. Maddox had sandwiches ready for them.

No word had been heard from the three scientists who had gone to the
power plant. Maria called, anxious about her father.

"I'm worried, Ken," she said. "What would happen to them out there if
the car breaks down and they have no place to go?"

"They'll be all right," Ken reassured her. "They probably found
something bigger than they expected at the dam. If they should have
trouble with the car they can find a phone along the road at some
farmhouse and let us know."

"I can't help worrying," said Maria. "Everything feels so strange
tonight, just the way it does before a big thunderstorm, as if