d, to say the least, so I tried other things."

"What we've got to figure put first of all, is whether it was caused
by a combination of changes, or whether it was the last setting you
used," Professor Jordan said. "If it was a combination of voltage and
frequency changes, then we've certainly got a problem on our hands."

All this time of course, Mary and Johnny had been standing more or
less open-mouthed, listening, and I, from my vantage point high on the
ceiling, had been taking it all in too.

"Can you think of any way to run the experiment over?" The professor
asked. "Do you think you can remember the formula for the plastic
plate?"

Jim thought a moment, snapped his fingers and said, "By golly, I
believe I've got another piece of that plastic around here somewhere.
I made it up at school and had to cut a little piece off so I could
get it in my suitcase. I'll see if I can find it." And stepping
gingerly around the plate in the hall he came back into the room and
started rummaging around in his luggage.

* * * * *

The professor looked at me. "Mr. Wilson, what sort of sensation did
you have when you stepped on the plate?"

"Well, as near as I can remember, I _don't_ remember," I said. "I
started to reach up and pull Duchess down, and the next thing I knew
my head hit the ceiling. Still got a bump big as an Easter egg."

"Did you have a giddy, light sensation?"

"No, as I say, I don't remember anything but the whack on the head."

About that time, Jim hollered, "Hey! I found it! Now maybe we can find
out what goes on here."

Jim and the professor very carefully disconnected the transformer from
the plate in the hall, made sure the dial settings were the same,
then hooked up the new plate. It was a lot smaller than the first one,
being only about six inches wide and two feet long.

"I wonder if shape has anything to do with it?" the professor mused.

"We'll find out in a minute," said Jim. "Everybody stand back now, and
I'll plug in the transformer."

He plugged it in and in a few seconds the plate began to glow the same
as the other one. "We'll give it a few more seconds," Jim said, "then
we'll see if it works."

The professor fumbled around in his pockets, started to toss his pipe
onto the plate, thought better of it and put it back in his pocket.
Johnny, who had been watching the whole proceedings, pulled out his
Boy Scout knife. "You can use this, Professor."

P