beam is stopped by a cloud, which is many
mist-droplets in one place. It's scattered until it simply doesn't
penetrate!" Lockley suddenly seemed indignant at his own failure to
see something that had been so obvious all along. "If we could make a
cloud of ions, it should stop the terror beam as clouds stop light! We
could--"

Again he stopped short, and Jill's expression changed. She looked
confident again. She even looked proud as she watched Lockley
wrestling with his problem, unconsciously snapping his fingers.

"Vale and I," he said jerkily, "had electronic base-measuring
instruments. Some of their elements had to be buried in plastic
because otherwise they ionized the air and leaked current like a
short. If I had that instrument now--No. I'd have to take the plastic
away and it couldn't be done without smashing things."

"What would happen," asked Jill, "if you made what you're thinking
about?"

"I might," said Lockley. "I just possibly might make a gadget that
would create a cloud of ions around the person who carried it. And it
might reflect some of the terror beam and refract the rest so none got
through to the man!"

Jill said hopefully, "Then tonight we go into a deserted town and
steal the things you need...."

Lockley interrupted in a relieved voice, "No-o-o-o. What I need, I
think, is a cheese grater and the pocket radio. And there should be a
cheese grater in the house."

He listened at the barn door gap, and then went out. Presently he was
back. He had not only a cheese grater but also a nutmeg grater. Both
were made of thin sheet metal in which many tiny holes had been
punched, so that sharp bits of torn metal stood out to make the
grating surface. Lockley knew that sharp points, when charged
electrically, make tiny jets of ionized air which will deflect a
candle flame. Here there were thousands of such points.

He set to work on the car seat, pushing the pistol with its three
remaining bullets out of the way. The pistol was reserved for Jill in
case of untoward events, when it would be of little or no practical
value.

He operated on the tiny radio with his pocket-knife to establish a
circuit which should oscillate when the battery was turned on. There
was induction, to raise the voltage at the peaks and troughs of the
oscillations. A transistor acted as a valve to make the oscillations
repeated surges of current of one sign in the innumerable sharp points
of the graters. And there was an