that it is a field of subnormal electronic
balance--in effect, the result of de-electroniration. It was
found, nevertheless, that stars close to the limb of the sun
appeared, not in their true positions, but shifted in just
the directions and with the amount of shift Einstein
predicted. The light rays coming from them to the eye of the
observer on Earth were curved in passing so close to the
sun. But the color-bands of their spectrums were unaltered.

And some of the stars actually were behind the sun, yet
because of the curved path of the light, were visible. I
mention this because it is an important aspect of the
subject of mechanical invisibility.

With the foregoing factors, the secret of mechanical
invisibility is constructed. Gracely, an American--following
a long series of world-wide experiments, tests of current
strength, frequencies of oscillation, suitable metals, etc.,
which I cannot detail here--in 1955 was the final developer
of the mechanisms subsequently used in the X-flyers.

Gracely produced what he christened "aluminoid-spectrite"--a
light-weight alloy which, when carrying an oscillating
electronic current of the proper frequency, produced the
effects I have described. It absorbed from the light rays
coming from the metal, all the colors of the solar spectrum,
well beyond the range of the human eye at both ends of the
scale. The result was a "visible nothingness."

A moment's thought will make clear that term. A visible
nothingness is not invisibility. The fact that something was
there but could not be seen was obvious. A black hat with a
light on it and placed against an average background is
almost as easy to see as a white hat. Gracely's first crude
experiments were made with an aluminoid-spectrite cube--a
small brick a foot in each dimension. The cube glowed,
turned, dark, then black, then was gone. He had it resting
on a white table, with a white background. And the fact that
the cube was still there, was perfectly obvious. It was as
though a hole of nothingness were set against the white
table. It outlined the cube; reconstructed it so that for
practical purposes the eye saw not a white, aluminoid brick,
but a dead black one.

And this is very much what a man sees when he stares at his
black