accurate enough to check that--and emerge
on the other side. Thus, you can look at a body so filmed, and not see
it: your gaze travels _around_ it and rests on objects in a straight
line behind it. But you'll see for yourself in a moment. Pull that
switch, there, will you? And leave it on for two full minutes after you
have ceased to see me."

Straight and tall, a figure encased in shimmering crystal, the scientist
stood on the metal plate. Hesitant, with the superstitious dread growing
in his heart, the Secretary stood with his hand on the switch. That hand
pulled the switch down....

Soundlessly the overhead metal ring began to whirl, gathering speed with
every second. And then, though he had known in advance something of what
was coming, the Secretary could not suppress a shout of surprise.

The man before him on the metal plate was vanishing.

* * * * *

Slowly he disappeared from view--slowly, as an object sinking deeper and
deeper into clear water disappears. Now the face was but a white blob.
Now the entire body was but a misty blur. And now a shade, a wavering
shadow, alone marked Winter's presence.

The Secretary could not have told the exact instant when that last faint
blur oozed from sight. He only knew that at one second he was gazing at
it--and at the next second his eyes rested on a rack of test-tubes on
the wall beyond the plate.

He looked at his watch. Sweat glistened in tiny points on the hand that
held the switch. It was all so like death, this disappearance--as if he
had thrown the switch that electrocuted a man.

The specified two minutes passed. He cut off the power. The great ring
lost speed, stopped whirling. And on the plate was--nothing.

At least it seemed there was nothing. But a moment later a deep voice
sounded out: "I guess I'm invisible, all right, according to the
expression on your face."

"You are," said the Secretary, mopping his forehead, "except when you
speak. Then I have the bizarre experience of seeing glimpses of teeth,
tongue and throat hanging in mid-air. I'd never have believed it if I
hadn't witnessed it myself! That paint of yours is miraculous!"

"A little complicated, but hardly miraculous. It has a cellulose base,
and there is in it a small per cent of powdered crystal--but the rest
I'll keep locked in my brain alone till my country has need of it."

The glimpses of teeth and tongue and throat ceased. In spite of himself,
the