had
to do was tap that key and they would know, beyond all argument, whether
or not they had dipped into the awful heart of material energy; whether,
finally, they held in their grasp the key to the release of energy that
would give the System power to spare.

His glance lifted from the keyboard, looked out the observation port.
Through the inkiness of space ran a faint blue thread, a tiny line that
stretched from the ship and away until it was lost in the darkness of
the void.

One hundred thousand miles away, that thread touched the surface of a
steel ball bearing ... a speck in the immensity of space.

He thought about that little beam of blue. It took power to do that,
power to hold a beam tight and strong and steady through the stress of
one hundred thousand miles. But it had to be that far away ... and they
had that power. From the bowels of the ship came the deep purr of it,
the angry, silky song of mighty engines throttled down.

He heard Harry Wilson shuffling impatiently behind him, smelled the
acrid smoke that floated from the tip of Wilson's cigarette.

"Might as well punch that key, Russ," said Manning's cool voice. "We
have to find out sooner or later."

Russ's finger hovered over the key, steadied and held. When he punched
that key, if everything worked right, the energy in the tiny ball
bearing would be released instantaneously. The energy of a piece of
steel, weighing less than an ounce. Over that tight beam of blue would
flash the impulse of destruction....

His fingers plunged down.

Space flamed in front of them. For just an instant the void seemed
filled with an angry, bursting fire that lapped with hungry tongues of
cold, blue light toward the distant planets. A flare so intense that it
was visible on the Jovian worlds, three hundred million miles away. It
lighted the night-side of Earth, blotting out the stars and Moon,
sending astronomers scurrying for their telescopes, rating foot-high
streamers in the night editions.

Slowly Russ turned around and faced his friend.

"We have it, Greg," he said. "We really have it. We've tested the
control formulas all along the line. We know what we can do."

"We don't know it all yet," declared Greg. "We know we can make it work,
but I have a feeling we haven't more than skimmed the surface
possibilities."

* * * * *

Russ sank into a chair and stared about the room. They knew they could
generate alternating curr