ig 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.

Bad for the Martians.

"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 exhibition 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 passers-by. The Fire Department
did not dare touch it. To blow it up seemed a dangerous expedient,
because already new buildings had been erected in its neighborhood,
and their safety would be imperiled by the flying fragments. The fact
happened to come to my knowledge.

"Here is an opportunity," I said to Mr. Edison, "to try the powers of
your machine on a large scale."

"Capital!" he instantly replied. "I shall go at once."

Disintegrating a Building.

For the work now in hand it was necessary to employ a battery of
disintegrators, since the field of destruction covered by each was
comparatively limited. All of the impending portions of the wall must be
destroyed at once and together, for otherwise the danger would rather
be accentuated than annihilated. The disintegrators were placed upon
the roof of a neighboring building, so adjusted that their fields of
destruction overlapped one another upon the wall. Their indexes were
all set to correspond with the vibration period of the peculiar kind