sm, and he was sure it was going to be
successful this time. Ned watched him prepare the selenium
plates--plates that were so sensitive to illumination that, in the
dark, the metal would hardly transmit a current of electricity, but
in the light would do so readily, its conductivity depending on the
amount of light it received.

"There, I guess we're all ready, Ned," announced Tom, at last.
"Now you go to your little coop, and I'll shut myself up in mine.
We can talk over the telephone."

Seated in the little booth in one of the smaller of Tom's shops,
Ned proceeded with his part in the new experiment. A small shelf
had been fitted up in the booth, or closet, and on this was the
apparatus, consisting of a portable telephone set, and a small
box, in which was set a selenium plate. This plate had been wet by
a spray of water in order to test Tom's new theory.

In a similar booth, several hundred feet away, and in another
building, Tom took his place. The two booths were connected by
wires, and in each one was an electric light.

"All ready, Ned?" asked Tom, through the telephone.

"All ready," came the answer.

"Now then, turn on your switch--the one I showed you--and look
right at the sensitized plate. Then turn out your light, and
slowly turn it on. It's a new kind, and the light comes up
gradually, like gas or an oil lamp. Turn it on easily."

"I get you, Tom."

Ned did as requested. Slowly the illumination in the booth
increased.

"Do you get anything, Tom?" asked Ned, over the wire.

"Not yet," was the somewhat discouraged answer. "Go ahead, turn on
more light, and keep your face close to the plate."

Ned did so.

"How about it now?" he asked, a moment later.

"Nothing--yet," was the answer. And then suddenly Tom's voice rose
to a scream over the wire.

"Ned--Ned! Quick!" he called. "Come here--I--I--"

The voice died off into a meaningless gurgle.

CHAPTER X

MIDNIGHT VISITORS

Ned Newton never knew exactly how he got out of the telephone
booth. He seemed to give but one jump, tearing the clamped
receiver from his ear, and almost upsetting the photo apparatus in
his mad rush to help Tom. Certain it is, however, that he did get
out, and a few seconds later he was speeding toward the shop where
Tom had taken his position in a booth.

Ned burst in, crying out:

"Tom! What is it? What happened? What's the matter?"

There was no answer. Fearing the worst, Ned hurried to the small