trike its edge, bit his lip as his
friend teetered on the rim and swayed slowly outward. Then Darl found
his balance. An imperative gesture sent the watcher back to his post,
his sorrel-topped head shaking slowly in wonderment.

* * * * *

Darl Thomas ran headlong up the staircase that spiralled through the
dim cavern. "No mistake about it," he muttered. "I saw something
moving outside that hole. Two little leaks before, and now this big
one. There's something a lot off-color going on around here."

Quickly he reached the little room at the summit. He flung the canvas
cover from the peri-telescope screen. Tempered by filters as it was
the blaze of light from outside hit him like a physical blow. He
adjusted the aperture and beat eagerly over the view-table.

Vacation jaunts and travel view-casts have made the moon's landscape
familiar to all. Very similar was the scene Darl scanned, save that
the barren expanse, pitted and scarred like Luna's, glowed almost
liquid under the beating flame of a giant sun that flared in a black
sky. Soundless, airless, lifeless, the tumbled plain stretched to a
jagged horizon.

The Earthman depressed the instrument's eye, and the silvered outside
of the Dome, aflame with intolerable light, swept on to the screen
disk. The great mirror seemed alive with radiant heat as it shot back
the sun's withering darts. The torrid temperature of the oven within,
unendurable save to such veterans of the far planets as Darl and Jim
Holcomb, was conveyed to it through the ground itself. The direct rays
of the sun, nearer by fifty million miles than it is to Earth, would
have blasted them, unprotected, to flaked carbon in an eye-blink.

An exclamation burst from Darl. A half-inch from the Dome's blazing
arc, a hundred yards in actuality, the screen showed a black fleck,
moving across the waste! Darl quickly threw in the full-power lens,
and the image leaped life-size across the table. The black fleck was
the shadow of a space-suited figure that lumbered slowly through the
viscous, clinging footing. How came this living form, clad in gleaming
silver, out there in that blast-furnace heat? In one of the space
suit's claw-like hands a tube flashed greenly.

* * * * *

Darl's hand shot out to the trigger of the beam-thrower. Aimed by the
telescope's adjustment, the ray that could disintegrate a giant space
flier utterly flared out at his fin