ly by children, but also by two adults, and their testimony agrees
completely with that of the children. The fifth case is similar to the
first: a ten year old boy disappeared without trace. The whole city is
in a reign of terror."

* * * * *

The telephone at Carpenter's elbow rang and he answered it. A short
conversation took place and he turned to me with a grim face as he hung
up the receiver.

"Another case has just been reported to police headquarters from Beverly
Hills," he said. "Again the child was seen to be lifted into the air by
some invisible means and disappeared. The sound of a motor was plainly
heard by five witnesses, who all agree that it was just, above their
heads, but that nothing could be seen."

"Was it in broad daylight?"

"Less than an hour ago."

"But, Jim, that's impossible!"

"Why is it impossible?"

"It would imply the invisibility of a tangible substance; of a solid."

"What of it?"

"Why, there isn't any such substance. Nothing of the sort exists."

Carpenter pointed to one of the windows of his laboratory.

"Does that window frame contain glass or not?" he asked.

I strained my eyes. Certainly nothing was visible.

"Yes," I said at a venture.

He rose and thrust his hand through the space where the glass should
have been.

"Has this frame glass in it?" he asked, pointing to another.

"No."

He struck the glass with his knuckle.

"I'll give up," I replied. "I am used to thinking of glass as being
transparent but not invisible; yet I can see that under certain light
conditions it may be invisible. Granted that such is the case, do you
believe that living organisms can be invisible?"

"Under the right conditions, yes. Has any observer been able to see any
of the purple amoeba which we know are so numerous on the outer side of
the heaviside layer?"

"Not until they have entered the hole through the layer."

"And yet those amoeba are both solid and opaque, as you know. Why is it
not possible that men, or intelligences of some sort, are in the air
about us and yet are invisible to our eyes!"

"If they are, why haven't we received evidence of it years ago?"

"Because there has only been a hole through the heaviside layer for six
years. Before that time they could not penetrate it any more than poor
Hadley could with his space ship. They have not entered the hole earlier
because it is a very small one, at present only some two hundred