ked past and vanished up ahead.
And, by this, Chet knew that their tremendous momentum was unchecked.
Though he was using the great stern blast to slow the ship, it was
driving stern-first into outer space. Nor, for twenty hours, was there
a change, more than a slackening of the breathless speed with which
the lights went past.

Twenty hours--and then Chet knew that they were in all truth hung
motionless, and he prayed that his figures that told him this were
correct.... More timeless minutes, an agony of waiting--and a
dimly-glowing mass that was ahead approached their bow, swung off and
vanished far astern. And, with its going, Chet knew that the return
trip was begun.

He gave Harkness the celestial bearing marks and relinquished the
helm. "Full speed ahead as you are," he ordered: "then at
nineteen-forty on W.S. time, we'll cut it and ease on bow repulsion to
the limit."

And, despite the strangeness of their surroundings, the ceaseless,
murmuring roar of the exhaust, the weird world outside, where endless
space was waiting for man's exploration--despite the deadly menace
that threatened, Chet dropped his head upon his outflung arms and
slept.

* * * * *

To his sleep-drugged brain it was scarcely a moment until a hand was
dragging at his shoulder.

"Forty-seven hours!" the voice of Schwartzmann was saying.

And: "Some navigating!" Harkness was exclaiming in flattering
amazement. "Wake up, Chet! Wake up! The Dark Moon's in sight. You've
hit it on the nose, old man: she isn't three points off the sights!"

The bow-blast was roaring full on. Ahead of them Chet's sleepy eyes
found a circle of violet; and he rubbed his eyes savagely that he
might take his bearings on Sun and Earth.

As it had been before, the Earth was a giant half-moon; like a
mirror-sphere it shot to them across the vast distance the reflected
glory of the sun. But the globe ahead was a ghostly world. Its black
disk was lost in the utter blackness of space. It was a circle, marked
only by the absence of star-points and by the halo of violet glow that
edged it about.

Chet cut down the repelling blast. He let the circle enlarge, then
swung the ship end for end in mid-space that the more powerful stern
exhaust might be ready to counteract the gravitational pull of the new
world.

Again those impalpable clouds surrounded them. Here was the enveloping
gas that made this a dark moon--the gas, if Harkness' theo