ness struggling
to throw off his two guards. "Walt," he called loudly, "take it easy!
For God's sake, Walt, keep your head!"

This, Chet sensed, was no time for resistance. Let Schwartzmann go
ahead with his plans; let him think them complacent and unresisting;
let Max pilot the ship; then watch for an opening when they could land
a blow that would count! He heard Schwartzmann laughing now, laughing
as if he were enjoying something more pleasing than the struggles of
Walt.

* * * * *

Chet was standing by the controls. The metal instrument-table was
beside him; above it was the control itself, a metal ball that hung
suspended in air within a cage of curved bars.

It was pure magic, this ball-control, where magnetic fields crossed
and recrossed; it was as if the one who held it were a genie who could
throw the ship itself where he willed. Glass almost enclosed the cage
of bars, and the whole instrument swung with the self-compensating
platform that adjusted itself to the "gravitation" of accelerated
speed. The pilot, Max, had moved across to the instrument-table, ready
for the take-off.

Schwartzmann's laughter died to a gurgling chuckle. He wiped his eyes
before he replied to Harkness' question.

"Leave you," he said, "in one place? _Nein!_ One here, the other
there. A thousand miles apart, it might be. And not all three of you.
That would be so unkind--"

He interrupted himself to call to Kreiss who was opening the port.

"No," he ordered; "keep it closed. We are not going outside; we are
going up."

But Kreiss had the port open. "I want a man to get some fresh water,"
he said; "he will only be a minute."

He shoved at a waiting man to hurry him through the doorway. It was
only a gentle push; Chet wondered as he saw the man stagger and grasp
at his throat. He was coughing--choking horribly for an instant
outside the open port--then fell to the ground, while his legs jerked
awkwardly, spasmodically.

Chet saw Kreiss follow. The scientist would have leaped to the side of
the stricken man, whose body was so still now on the sunlit rock; but
he, too, crumpled, then staggered back into the room. He pushed feebly
at the port and swung it shut. His face, as he turned, was drawn into
fearful lines.

"Acid!" He choked out the words between strangled breaths.
"Acid--sulfuric--fumes!"

* * * * *

Chet turned quickly to the spectro-analyzer; the line