developed, of the law of
harmonic vibrations, extending from atoms and molecules at one end of
the series up to the worlds and suns at the other end, that Mr. Edison
based his invention.

Every kind of substance has its own vibratory rhythm. That of iron
differs from that of pine wood. The atoms of gold do not vibrate in the
same time or through the same range as those of lead, and so on for all
known substances, and all the chemical elements. So, on a larger scale,
every massive body has its period of vibration. A great suspension
bridge vibrates, under the impulse of forces that are applied to it, in
long periods. No company of soldiers ever crosses such a bridge without
breaking step. If they tramped together, and were followed by other
companies keeping the same time with their feet, after a while the
vibrations of the bridge would become so great and destructive that it
would fall in pieces. So any structure, if its vibration rate is known,
could easily be destroyed by a force applied to it in such a way that it
should simply increase the swing of those vibrations up to the point of
destruction.

Now Mr. Edison had been able to ascertain the vibratory swing of many
well known substances, and to produce, by means of the instrument which
he had contrived, pulsations in the ether which were completely under
his control, and which could be made long or short, quick or slow, at
his will. He could run through the whole gamut from the slow vibrations
of sound in air up to the four hundred and twenty-five millions of
millions of vibrations per second of the ultra red rays.

Having obtained an instrument of such power, it only remained to
concentrate its energy upon a given object in order that the atoms
composing that object should be set into violent undulation, sufficient
to burst it asunder and to scatter its molecules broadcast. This the
inventor effected by the simplest means in the world--simply a parabolic
reflector by which the destructive waves could be sent like a beam of
light, but invisible, in any direction and focused upon any desired
point.

I had the good fortune to be present when this powerful engine of
destruction was submitted to its first test. We had gone upon the roof
of Mr. Edison's laboratory and the inventor held the little instrument,
with its attached mirror, in his hand. We looked about for some object
on which to try its powers. On a bare limb of a tree not far away, for
it was late in f