tive power. Expansion of gas. That accounts for the cold and
the vapor. Suddenly expanded it would be intensely cold. The moisture of
the air would condense, freeze. But how could they carry it? Or"--he
frowned for a moment, brows drawn over deep-set gray eyes--"or generate
it? But that's crazy--that's impossible!"

"So is the whole matter," the Secretary reminded him. "With the
information Mr. Thurston and Mr. Riley have given us, the whole affair
is beyond any gage our past experience might supply. We start from the
impossible, and we go--where? What is to be done?"

"With your permission, sir, a number of things shall be done. It would
be interesting to see what a squadron of planes might accomplish, diving
on them from above. Or anti-aircraft fire."

* * * * *

"No," said the Secretary of War, "not yet. They have looked us over,
but they have not attacked. For the present we do not know what they
are. All of us have our suspicions--thoughts of interplanetary
travel--thoughts too wild for serious utterance--but we know nothing.

"Say nothing to the papers of what you have told me," he directed
Thurston. "Lord knows their surmises are wild enough now. And for you,
General, in the event of any hostile move, you will resist."

"Your order was anticipated, sir." The General permitted himself a
slight smile. "The air force is ready."

"Of course," the Secretary of War nodded. "Meet me here to-night--nine
o'clock." He included Thurston and Riley in the command. "We need to
think ... to think ... and perhaps their mission is friendly."

"Friendly!" The two flyers exchanged glances as they went to the door.
And each knew what the other was seeing--a viscous ocherous mass that
formed into a head where eyes devilish in their hate stared coldly into
theirs....

"Think, we need to think," repeated Thurston later. "A creature that is
just one big hideous brain, that can think an arm into existence--think
a head where it wishes! What does a thing like that think of? What
beastly thoughts could that--that _thing_ conceive?"

"If I got the sights of a Lewis gun on it," said Riley vindictively,
"I'd make it think."

"And my guess is that is all you would accomplish," Thurston told him.
"I am forming a few theories about our visitors. One is that it would be
quite impossible to find a vital spot in that big homogeneous mass."

The pilot dispensed with theories: his was a more literal mind. "