the quartz glass used for view panels
in his space and undersea craft.

"What's it for, son?" Mr. Swift asked, after studying the setup
curiously.

"Don't laugh, Dad, but I'm trying to produce a brain of pure energy. A
substitute for Exman, so we can go ahead with our sensing experiments."

Mr. Swift reacted with keen interest and offered to help. "But remember,
son," he cautioned, "at best you can only hope to produce an ersatz
brain energy--which will be vastly different from the real thing. Don't
forget, Tom, the mind of a human being or any thinking inhabitant of our
universe is based on a divine soul. No scientist must ever delude
himself into thinking he can copy the work of our Creator."

"I know that, Dad," Tom said soberly. "Man's work will always be a crude
groping, compared to the miracles of Nature. All I'm hoping to come up
with here is a sort of stimulus-response unit that we can use for
testing any sensing apparatus we devise."

The two scientists plunged into work. First, a bank of delicate gauges
was assembled to record precisely every electrical reaction that took
place inside the sphere. Then Tom threw a switch, shooting a powerful
bolt of current across the electrodes. The field strength of the
electromagnets, controlled by rheostats, instantly shaped the charge
into a glowing ball of fire!

"Wow! A real hothead!" Bud wisecracked, trying to hide his excitement.

Tom grinned as he twirled several knobs and checked the gauges. The
slightest variation in field strength triggered an instant response from
the ball of energy. Mr. Swift tried exposing it to radio and repelatron
waves. Each time the gauges showed a sensitive reaction.

"Looks as if we're in business, Dad!" Tom said jubilantly.

Bud left soon afterward as the two Swifts buckled down to work on the
problem of perfecting an apparatus to simulate the human senses. Each
concentrated on a different line of approach.

At noon they broke off briefly for a lunch wheeled in by Chow. Then
silence settled again over the laboratory.

Tom had rigged up a jointed, clawlike mechanical arrangement with
sensitive diaphragms in its "finger tips." The diaphragms were connected
to a transistorized circuit designed to modulate the field current to
the electromagnets.

Suddenly the young inventor looked up at his father with a glow of
triumph.

"Dad, I just got a reaction to my sense-of-touch experiment!"

CHAPTER XVII

AN URGENT WARNING