the ray
screen little work to do.

"Now your job is to design the apparatus in a form that machines can
make automatically. We tried doing it ourselves for the fun of it, but
we couldn't see how we could make a machine that didn't need at least
two humans to supervise."

"Well," grinned Fuller, "you have it all over me as scientists, but as
economic workers--two human supervisors to make one product!"

"All right--we agree. But no, let's see you--Lord! What was that?" Morey
started for the door on the run. The building was still trembling from
the shock of a heavy blow, a blow that seemed much as though a machine
had been wrecked on the armored roof, and a big machine at that. Arcot,
a flying suit already on, was up in the air, and darting past Morey in
an instant, streaking for the vertical shaft that would let him out to
the roof. The molecular ray pistol was already in his hand, ready to
pull any beams off unfortunate victims pinned under them.

In a moment he had flashed up through the seven stories, and out to the
roof. A gigantic silvery machine rested there, streamlined to
perfection, its hull dazzingly beautiful in the sunlight. A door opened,
and three tall, lean men stepped from it. Already people were collecting
about the ship, flying up from below. Air patrolmen floated up in a
minute, and seeing Arcot, held the crowd back.

The strange men were tall, eight feet or more in height. Great, round,
soft brown eyes looked in curiosity at the towering multicolored
buildings, at the people floating in the air, at the green trees and the
blue sky, the yellowish sun.

Arcot looked at their strangely blotched and mottled heads, faces, arms
and hands. Their feet were very long and narrow, their legs long and
thin. Their faces were kindly; the mottled skin, brown and white and
black, seemed not to make them ugly. It was not a disfigurement; it
seemed oddly familiar and natural in some reminiscent way.

"Lord, Arcot--queer specimens, yet they seem familiar!" said Morey in an
undertone.

"They are. Their race is that of man's first and best friend, the dog!
See the brown eyes? The typical teeth? The feet still show the traces of
the dog's toe-step. Their nails, not flat like human ones but rounded?
The mottled skin, the ears--look, one is advancing."

One of the strangers walked laboriously forward. A lighter world than
Earth was evidently his home. His great brown eyes fixed themselves on
Arcot's. Arcot watche