ly now, singing the low song of power held
in leash.

But then they screamed like a buzz saw biting into an iron-hard stick of
white oak. Screamed in a single, frightful agony as they threw into the
protecting wall that enclosed the _Invincible_ all the power they could
develop.

The air of the ship was instantaneously charged with a hazy, bluish
glow, and the sharp, stinging odor of ozone filled the ship.

* * * * *

Outside, an enormous burst of blue-white flame splashed and spattered
around the _Invincible_. Living lightning played in solid, snapping
sheets around the vision port and ran in trickling blazing fire across
the plates.

Russ cried out and backed away, holding his arm before his eyes. It was
as if he had looked into a nova of energy exploding before his eyes.

In the instant the scream died and the splash of terrific fire had
vanished. Only a rapidly dying glow remained.

"What was it?" asked Russ dazedly. "What happened? Ten engines every one
of them capable of over five billion horsepower and every one of them
screaming!"

"Craven," said Greg grimly. "He let us have everything he had. He simply
drained his accumulator stacks and threw it all into our face. But he's
done now. That was his only shot. He'll have to build up power now and
that will take a while. But we couldn't have taken much more."

"Stalemate," said Russ. "We can't hurt him, he can't hurt us."

"Not by a damn sight," declared Greg. "I still have a trick or two in
mind."

He tried them. From the _Invincible_ a fifty-billion-horsepower bolt of
living light and fire sprang out as all ten engines thundered with an
insane voice that racked the ship.

Fireworks exploded in space when the bolt struck Craven's ship. Screen
after screen exploded in glittering, flaming sparks, but the ship rode
the lashing charge, finally halted the thrust of power. The beam glowed
faintly, died out.

Perspiration streamed down Greg's face as he bent over a calculator and
constructed the formula for a magnetic field. He sent out a field of
such unimaginable intensity that it would have drawn any beryl-steel
within a mile of it into a hard, compact mass. Even the _Invincible_, a
hundred miles away, lurched under the strain. But Craven's ship, after
the first wild jerk, did not move. A curious soft glow spread out from
the ship, veered sharply and disappeared in the magnetic field.

Greg swore softly. "He's cutting it