two score feet
away, and the other absolutely useless. All over the still-glowing case
it spat its hits, but the glasslike substance resisted it completely,
and remained unscathed.

Carse swore harshly. He hurled one empty gun at the case, turned with a
last salvo of shots at the coolies, and then was up on the pile and
leaping for Friday's hands.

They caught and gripped his, swung him once--twice--and hauled him
swiftly out. But as the Hawk disappeared he shouted down the case:

"I'll be back!"

CHAPTER XIII

_The Final Mystery_

On the roof, Carse quickly scanned their situation. They were standing
on the hub of the four-winged building. Far to the left was one set of
the dome's great and small port-locks; exactly opposite was the other.
Near the left hand ports; a little "north," lay the _Scorpion_. The
whole area enclosed was a flat plain of gray soil.

Looming over the great transparent dome hung the flaming disk of
Jupiter, so oppressively near that it seemed about to crash onto the
asteroid. Its rays poured in a ruddy flood over the settlement, clearly
illuminating each detail; and comparatively close against the face of
the mighty planet they could see the whitish globe of Satellite III. It
offered the nearest haven. They might arrive famished, but in the
power-equipped space-suits which Friday was lugging they should be able
to span the gap.

The Hawk nodded to the port-locks on the left.

"That one," he snapped. "We'll have two chances, the _Scorpion_ and the
port, but the port's safest; we could never get the whole ship underway
and through the lock in time. To prevent pursuit, all we have to do is
leave the lock open after us."

They hastened along the roof of the wing that ran that way. As yet there
was no outside pursuit; most of the settlement's guards seemed to have
been concentrated in the attack on the laboratory. But Carse knew it
would only be a matter of seconds before coolies would emerge from half
a dozen different points. He was trying to figure out which points they
were likely to be when there passed, perilously close, the spit of an
orange ray. He glanced back, to see the first of the crowd which had
broken into the laboratory come clambering up through the roof. Then, as
a second shot sizzled by, they arrived at the end of the wing.

* * * * *

Friday took the fifteen-foot drop without hesitation. Carse lowered
Leithgow to him