at down in a chair facing Halliday.

"You're afraid of something," he said bluntly. "Supposing you tell me
about it."

"As a matter of fact, I was meaning to," Halliday said. "You see, on
this section we're pretty well isolated from the rest of the Earth
stations on Mars. We receive all supplies and mail by a direct
materialization unit. No space craft puts in here. We're here all alone
and if anything happened to us all the data and work that has been
compiled might be lost."

As Halliday removed his glasses again with a quick aimless gesture, Ward
thought, "A lot you care about the records and data. It's your skin you
want to save."

Halliday coughed and replaced his glasses.

"This area is inhabited by a species of creature which I do not believe
has been classified. I do not know if they are human or if they possess
intelligence. I do not even know if they are 'alive' in the sense that
we speak of life. Possibly their energy is of electrical or
carboniferous origin, or it could be even vegetable in nature. As you
see I know little enough about these neighbors of ours, but I do know
that they are dangerous. They resent the work that is being done here."
Halliday frowned and twisted a pencil in his hands. "I'm not even sure
of that. Possibly they are without rational motivation at all. It may be
that they are merely moved to action by the sight of another object in
motion. But whatever their reason, they have been very troublesome.
That, really, is all I know about them. And that is the reason that I
exercise such care. I have a small periscope installed on the roof and
before I unlock the door I study the entire surrounding terrain to be
sure there are no Raspers in sight."

"Why do you call them Raspers?" Ward asked.

"Because of a peculiar sound that seems to emanate from them," Halliday
explained. "My former assistant and I had to call them something and
Raspers seemed as logical as anything else."

"Have you ever seen one of these--er--Raspers?" Ward asked.

"I'm not sure," Halliday said thoughtfully. He removed his glasses
again. "I've had two brushes with them, but I'm not sure that I saw them
distinctly either time. Possibly the picture that came to my mind,
later, was supplied by my imagination. But I know that there is
something very repellent and fearsome about them. I _felt_ that much."

Ward crossed his legs and lit a cigarette casually.

"Can these things be killed?" he asked.

"I don't kn