y stopped, breathless with astonishment.

"See the little airplane," Agnes said, pointing under the table.

Larry gasped.

Beneath the table stood a toy airplane. The spread of its glistening,
perfect wings was hardly three feet. A wonderful, delicate toy,
accurate in every detail of propeller, motor and landing gear, of
brace and rudder and aileron. Then he realized that it was no toy at
all, but a faithful miniature of a commercial plane. A complete, tiny
copy of one of the latest single-motor, cabin monoplane models.

"It looks like it would fly," he said "a friend of mine his a big
one, just like it! Taught me to fly it, last summer vacation. This is
the very image of it!"

"It will fly!" Agnes assured him, now composed enough to smile at his
amazement. "I have been with the doctor to the Pygmy Planet in it.

"You stand in the violet ray until you're about three inches high,"
she explained, "and then get into the plane. Then you fly up and into
the violet ray at the point where it touches the planet, and remain
there while you grow smaller. When you are the right size, all you
have to do is drop to the surface, and land. To come away, you rise
into the red ray and stay in it till you grow to proper size, when you
come down and land."

"You--you've actually done that?" he gasped. "It sounds like a fairy
story!"

* * * * *

"Yes, I've done it," she assured him. Then she shuddered
apprehensively. "And the things--the machine-monsters, Dr. Whiting
called them--have learned to do it, too. One of them came down the red
ray, and attacked him. The doctor had a gun--but what could he do
against one of those?" She shivered.

"It carried him back up the violet beam. Just a few minutes ago, I
started to phone you. Then I was afraid you would be hurt--"

"Me, hurt?" Larry burst out. "What about you, here alone?"

"It was my business. Dr. Whiting told me there might be danger, when
he hired me."

"And now, what can we do?" Larry demanded.

"I don't know," she said slowly. "I'm afraid one of the monsters will
be back after a new victim. We could smash the apparatus, but it is
too wonderful to be destroyed. And besides, Dr. Whiting may have
escaped. He may be alive there, in the deserts!"

"We might fly up, in the little plane," Larry proposed, doubtfully. "I
think I could pilot it. If you want--"

The girl's body stiffened. Her brown eyes widened with sudden dread,
and her small