d, then a fraction lower. The
needle was flickering now, impossible to decide whether it was dropping
or not. And in the engine rooms, ten great generators howled in their
attempt to make that needle move up the dial again.

Russ lit his pipe, his eyes not leaving the dial. The needle was
creeping lower again. Down to three miles a second now.

He puffed clouds of smoke and considered. Saturn fortunately was ninety
degrees around in his orbit. On the present course, only Neptune
remained between them and free space. Pluto was far away, but even if it
had been, it really wouldn't count, for it was small and had little
attraction.

In a short while Ganymede and Callisto would be moving around on the far
side of Jupiter and that might help. Everything counted so much now.

The dial was down to two miles a second and there it hung. Hung and
stayed. Russ watched it with narrowed eyes. By this time Craven
certainly would have given up much hope of help from Jupiter. If the big
planet couldn't have helped him before, it certainly couldn't now. In
another hour or two Earth would transit the Sun and that would cut down
the radiant energy to some degree. But in the meantime Craven was
loading his photo-cells and accumulators, was laying up a power reserve.
As a last desperate resort he would use that power, in a final attempt
to break away from the _Invincible_.

Russ waited for that attempt. There was nothing that could be done about
it. The engines were developing every watt of power that could be urged
out of them. If Craven had the power to break away, he would break
away ... that was all there would be to it.

An hour passed and the needle crept up a fraction of a point. Russ was
still watching the dial, his mind foggy with concentration.

* * * * *

Suddenly the _Invincible_ shuddered and seemed to totter in space, as if
something, some mighty force, had struck the ship a terrific blow. The
needle swung swiftly backward, reached one mile a second, dipped to half
a mile.

Russ sat bolt upright, holding his breath, his teeth clenched with death
grip upon the pipe-stem.

Craven had blasted with everything he had! He had used every last
trickle of power in the accumulators ... all the power he had been
storing up.

Russ leaped from the chair and raced to the periscopic mirror.
Stooping, he stared into it. Far back in space, like a silver bauble,
swung Craven's ship. It swung back and