down as fast as I try to build it
up," he explained, "and I can't move it any nearer."

From Craven's ship lashed out another thunderbolt and once again the
engines screamed in terrible unison as they poured power into the ship's
triple screen. The first screen stopped all material things. The second
stopped radiations by refracting them into the fourth dimension. The
third shield was akin to the anti-entropy field, which stopped all
matter ... and yet the ten engines bellowed like things insane as Craven
struck with flaming bolts, utilizing the power he had absorbed from the
fifty billion horsepower Greg had thrown at him.

There was anger in Greg Manning's face ... a terrible anger. His fists
knotted and he shook them at the gleaming ship that lay far down near
Jupiter.

"I've got one trick left," he shouted, almost as if he expected Craven
to hear. "Just one trick. Damn you, see if you can stop this one!"

He set up the pattern on the board and punched the activating lever. The
ten engines thrummed with power. Then the howling died away.

Four times they screamed and four times they ebbed into a gentle hum.

"Get on the navigation controls!" yelled Greg. "Be ready to give the
ship all you've got."

Greg leaped for the control chair, grasped the acceleration lever.

"Now," growled Greg, "look out, Craven, we're coming at you!"

Greg, teeth gritted, slammed the acceleration over.

Suddenly all space wrenched horribly with a nauseating, terrible thud
that seemed to strain at the very anchors of the Universe.

_CHAPTER EIGHTEEN_

Jupiter and the Jovian worlds leaped suddenly backward, turned swiftly
green, then blue, and faded in an instant into violet. The Sun spun
crazily through space, retreating, dimming to a tiny ruby-tinted star.

The giant generators in the _Invincible_ hummed louder now, continually
louder, a steel-throated roar that trembled through every plate, through
every girder, through every bit of metal in the ship.

The ship itself was plunging spaceward, streaking like a runaway star
for the depths of space beyond the Solar System. And behind it, caught
tight, gripped and held, Craven's ship trailed at the end of a tractor
field that bound it to the space-rocketing _Invincible_.

The acceleration compensator, functioning perfectly, had taken up the
slack as the ship had plunged from a standing start into a speed that
neared the pace of light. But it had never been built to stand