saw a second airplane
flying toward them, a larger one than the plane which he had flown.

It opened its helicopter wings and drifted downward. Kay saw a single
pilot, and, in the baggage compartment something that at first he did
not recognize. Then he recognized both this object and the aviator.

"It's Cliff," he whispered hoarsely. "He's brought the top!"

* * * * *

The crowd was milling about Cliff as he stepped out of the plane. Kay
broke through their midst, shouting to them to clear a space, that it
was their chance, their only chance. They heard him and obeyed. And
Cliff and Kay clasped hands, and there was Ruth beside them.

The two men carried the top out of the baggage compartment and set it
up.

"Thank God I came in time," Cliff hissed. "How long have we got, Kay?"

"Five minutes, I think," Kay answered, glancing at the oncoming wall.
"They're slow. Will it work, Cliff? God, when I found you'd gone last
night--"

Cliff did not answer. Ignoring Kay's offer of assistance, he fitted
the top tightly into its socket of craolite, much heavier than the
former one. Beneath this, three heavy craolite legs formed a sort of
tripod.

"I looked forward to this possibility, Kay," said Cliff, as he
adjusted the top and turned the clamps that held it in position.
"Sorry I had to deceive you, but you we're so set on the cosmic rays,
and I knew the psenium emanations wouldn't appeal to you. You wouldn't
have believed. I had a hunch Ruth would draw one of those numbers....
_How long?_"

The swaying masses of gray jelly were very near them. Cliff worked
feverishly at the top.

"Let me help. Cliff!"

"No! I'm through! Stand back!" shouted Cliff.

* * * * *

Even then--he regretted it afterward, and knew that he would regret it
to his dying day--even then the thought flashed through Kay's mind
that Cliff wanted all the glory. Behind him the milling, screaming
crowd was huddling, as if for protection. Slowly a wisp-like tentacle
protruded from the advancing wall. Kay swung his ax and lopped it from
the phantom body. But the wall was almost upon them, and from the
other side it was advancing rapidly.

"I'm ready! Stand back!" Cliff turned upon Kay, his face white, his
voice hoarse. "I've one request to make, Kay. Keep everybody back,
including you and Ruth. Nobody is to come within twenty-five yards of
this machine!"

"That shall be done," said Kay