means of a most ingenious and complicated
construction he had mastered the problem of how to produce, in a limited
space, electricity of any desired potential and of any polarity, and
that without danger to the experimenter or to the material experimented
upon. It is gravitation, as everybody knows, that makes man a prisoner
on the earth. If he could overcome, or neutralize, gravitation he could
float away a free creature of interstellar space. Mr. Edison in his
invention had pitted electricity against gravitation. Nature, in fact,
had done the same thing long before. Every astronomer knew it, but none
had been able to imitate or to reproduce this miracle of nature. When a
comet approaches the sun, the orbit in which it travels indicates that it
is moving under the impulse of the sun's gravitation. It is in reality
falling in a great parabolic or elliptical curve through space. But,
while a comet approaches the sun it begins to display--stretching out
for millions, and sometimes hundreds of millions of miles on the side
away from the sun--an immense luminous train called its tail. This train
extends back into that part of space from which the comet is moving. Thus
the sun at one and the same time is drawing the comet toward itself and
driving off from the comet in an opposite direction minute particles or
atoms which, instead of obeying the gravitational force, are plainly
compelled to disobey it. That this energy, which the sun exercises
against its own gravitation, is electrical in its nature, hardly anybody
will doubt. The head of the comet being comparatively heavy and massive,
falls on toward the sun, despite the electrical repulsion. But the atoms
which form the tail, being almost without weight, yield to the electrical
rather than to the gravitational influence, and so fly away from the sun.

Gravity Overcome.

Now, what Mr. Edison had done was, in effect, to create an electrified
particle which might be compared to one of the atoms composing the tail of
a comet, although in reality it was a kind of car, of metal, weighing some
hundreds of pounds and capable of bearing some thousands of pounds with
it in its flight. By producing, with the aid of the electrical generator
contained in this car, an enormous charge of electricity, Mr. Edison
was able to counterbalance, and a trifle more than counterbalance,
the attraction of the earth, and thus cause the car to fly off from the
earth as an electrified pith ball fl