el to determine whether it would be worthwhile
building a full-size machine with a reflector 250 feet in diameter.

Ken's father looked completely exhausted, but his smile was broader than
it had been for many weeks. "I'm confident we will prove the
practicability of this machine," he said. "After that, we will build a
really big one, and we'll tell the rest of the world how to do it. I
don't know how long it will take, but this will do the job. We'll get
them to build big ones in Tokyo and Pasadena and Stockholm, wherever
there's civilization enough to know how to do it; they can decontaminate
their own metals and build new engines that will run as long as
necessary. We've got the comet on the run!"

He hadn't meant to give a speech, but he couldn't help it. They were
right, and their staggering labors were nearly over, in this phase, at
least.

* * * * *

They slept from exhaustion that night. Ken was awakened in the
early-morning hours by the glare in his bedroom window. He sat up and
looked out. It seemed to be a very long time before he could let his
mind admit what his eyes saw.

Science Hall was in flames, the entire structure a mass of leaping,
boiling fire.

Ken ran from his room, crying the alarm.

In their separate rooms, his father and Dr. Larsen stared stupidly at
the flickering light as if also unable to comprehend the vastness of the
ruin. In frenzy of haste, they donned their clothes and ran from their
rooms.

Maria was awake as was Mrs. Maddox. "What is it?" they called. Then
they, too, saw the flames through the windows.

The men ran from the house, hatless, their tousled hair flying in the
night. Halfway up the hill, Ken called to his father, "You've got to
stop, Dad! Don't run like that!"

Professor Maddox came to a halt, his breath bursting from him in great
gasps. Ken said, "There's nothing we can do, Dad."

Dr. Larsen stopped beside them. "Nothing except watch," he agreed.

Slowly, they resumed their way. Behind, they heard the sounds of others
attracted by the fire. As they came at last to the brow of the hill, Ken
pointed in astonishment. "There's a crowd of people over there! Near the
burning building!"

He started forward. A shot burst in the night, and a bullet clipped the
tree over his head. He dropped to the ground. "Get down! They're firing
at us!"

As they lay prone, sickness crept through them simultaneously. "I know
who it is," Ken cried