troying dust. Art Matthews and the science club boys were once
again scouring the town for engine parts that could be cleaned and used
in assembling new and, this time, workable engines.

On Friday morning Professor Douglas came in late, after all the others
had been there for a couple of hours. He was panting from his rapid walk
up the hill. "Have you heard the news?" he exclaimed.

The others looked up. "What news?" Professor Maddox asked.

"A couple of farmers and ranchers from the south end of the valley rode
in about 3 o'clock this morning. They were half-dead. They said their
places and several others had been attacked last night. Everything in
the whole southern part of the valley, beyond the point, has been looted
and burned. Six families, still living on their own places were wiped
out."

"Who did it?" Professor Larsen exclaimed.

"Nomads! The ranchers say there's a band of over three thousand camped
down by Turnerville, about 20 miles from here. They've been moving
across the country, killing and looting everything that's in their way.
Now they're headed for Mayfield. They've heard about us having a big
cache of supplies."

All work in the laboratory ceased as the men gathered around Professor
Douglas. They stared into the distance, but their thoughts were alike.

"Three thousand," said Professor Maddox slowly. "We could put twice
that many good men against them. We ought to be able to stand them off,
if they attack. What's Hilliard doing about it?"

"He wants us all down there this morning. There doesn't seem to be much
question about him staying on as Mayor since this came up."

In a group the men left the half-completed experiments and made their
way down the hill to the City Hall. When they arrived they found the
Council chamber already filled. The Mayor and the councilmen were at
their conference table on the platform in front of the room.

At one side, facing both the leaders and the audience, were three
ragged, unshaven strangers in heavy boots and ill-fitting coats. They
had not bothered to remove the fur-lined caps from their heads.

Nomads, Ken thought. It was apparent what was going on.

"We're coming in," the center man was saying. His massive size and
strength showed even under the thick covering of clothes. "I say we're
coming in, and we either come peaceable and you treat us right or we
come in our own way. It doesn't make much difference to us how we do it.
You just call the shots,