ion explains the shifting of gravitational lines, the
changing and contortion of their direction. Twist gravity and you have a
perfect space drive. As good as negative gravity. Better, perhaps, more
easily controlled. Would make for more delicate, precise handling."

Russ laid down the sheaf of papers, lit his pipe and walked to the
apparatus.

"Here goes," he said.

His hand went out to the power lever, eased it in. With a roar the
material energy engine built within the apparatus surged into action,
sending a flow of power through the massive leads. The thunder mounted
in the room. The laboratory seemed to shudder with the impact.

Wilson, watching intently, cried out, a brief, choked-off cry. A wave of
dizziness engulfed him. The walls seemed to be falling in. The room and
the machine were blurring. Russ, at the controls, seemed horribly
disjointed. Manning was a caricature of a man, a weird, strange figure
that moved and gestured in the mad room.

Wilson fought against the dizziness. He tried to take a step and the
floor seemed to leap up and meet his outstretched foot, throwing him off
balance. His cigarette fell out of his mouth, rolled along the floor.

Russ was shouting something, but the words were distorted, loud one
instant, rising over the din of the apparatus, a mere whisper the next.
They made no sense.

There was a peculiar whistling in the air, a sound such as he had never
heard before. It seemed to come from far away, a high, thin shriek that
was torture in one's ears.

Giddy, seized with deathly nausea, Wilson clawed his way across the
floor, swung open the laboratory door and stumbled outdoors. He weaved
across the lawn and clung to a sun dial, panting.

He looked back at the laboratory and gasped in disbelief. All the trees
were bent toward the building, as if held by some mighty wind. Their
branches straining, every single leaf standing at rigid attention, the
trees were bending in toward the structure. _But there was no wind._

And then he noticed something else. No matter where the trees stood, no
matter in what direction from the laboratory, they all bent inward
toward the building ... and the whining, thundering, shrieking machine.

Inside the laboratory an empty bottle crashed off a table and smashed
into a thousand fragments. The tinkling of the broken glass was a
silvery, momentary sound that protested against the blasting thrum of
power that shook the walls.

Manning fought alo