all, sat a disconsolate crow.

"Good," said Mr. Edison, "that will do." He touched a button at the side
of the instrument and a soft, whirring noise was heard.

"Feathers," said Mr. Edison, "have a vibration period of three hundred
and eighty-six million per second."

He adjusted the index as he spoke. Then, through a sighting tube, he
aimed at the bird.

"Now watch," he said.

Another soft whirr in the instrument, a momentary flash of light close
around it, and, behold, the crow had turned from black to white!

"Its feathers are gone," said the inventor; "they have been dissipated
into their constituent atoms. Now, we will finish the crow."

Instantly there was another adjustment of the index, another outshooting
of vibratory force, a rapid up and down motion of the index to include a
certain range of vibrations, and the crow itself was gone--vanished in
empty space! There was the bare twig on which a moment before it had
stood. Behind, in the sky, was the white cloud against which its black
form had been sharply outlined, but there was no more crow.

"That looks bad for the Martians, doesn't it?" said the Wizard. "I have
ascertained the vibration rate of all the materials of which their war
engines, whose remains we have collected together, are composed. They
can be shattered into nothingness in the fraction of a second. Even if
the vibration period were not known, it could quickly be hit upon by
simply running through the gamut."

"Hurrah!" cried one of the onlookers. "We have met the Martians and they
are ours."

Such in brief was the first of the contrivances which Mr. Edison
invented for the approaching war with Mars.

And these facts had become widely known. Additional experiments had
completed the demonstration of the inventor's ability, with the aid of
his wonderful instrument, to destroy any given object, or any part of an
object, provided that that part differed in its atomic constitution, and
consequently in its vibratory period, from the other parts.

A most impressive public exhibit of the powers of the little
disintegrator was given amid the ruins of New York. On lower Broadway a
part of the walls of one of the gigantic buildings, which had been
destroyed by the Martians, impended in such a manner that it threatened
at any moment to fall upon the heads of the passersby. The Fire
Department did not dare touch it. To blow it up seemed a dangerous
expedient, because already new buildings had be