ingle conductor
of irregular surface, upon which is accumulated all the electricity that
was previously distributed over the surfaces of the millions of particles
that now compose it.

The tendency of an electric charge upon the surface of a conductor is to
take upon itself a position in which it may approach nearest to an equal
and opposite charge; or, if possible, to attain neutrality. If, then, a
cloud has a charge, and there is no other cloud above or near it, the
charge _induces_ on the adjacent earth surface electricity of the opposite
kind. Thus, assuming the cloud to be charged with positive electricity,
the subjacent earth will be in the negative state. The two
electricities[3] exert a strong tendency to combine or to produce
neutrality, whence there is a species of stress applied to the intervening
air. Possibly the cloud will be drawn bodily toward the earth more or less
rapidly, according as the charge is great or small. Or, on the other hand,
the cloud may roll on for leagues, carrying its influence with it, so that
the various portions of the earth underneath become successively charged
and discharged as the cloud progresses on its journey.

[Footnote 3: We may speak of two electricities or two electric states
without necessarily implying adherence either to the single or the double
"fluid" theory. Whether electricity be of two kinds or no, the fact
remains that there are two conditions, and all the features of this paper
may be explained with equal facility by the supporters of either
hypothesis.]

Should the cloud be near the earth, or should it be very highly charged,
the tension of the two electricities may be so great as to overcome the
resistance of the intervening air; and if this resistance should prove too
weak, what happens? How does the discharge show itself? It takes place in
the form of a lightning flash, and passing from the one surface to the
other--or, maybe, simultaneously from both--produces neutrality more or
less complete.

There has recently been a little discussion in these pages on the subject
of lightning, some having stated that they discerned the discharge to take
place upward--that is, from the earth toward the cloud. I will not venture
so far as to say whether or not the direction of the discharge is
discernible; possibly the flash may sometimes be long enough to enable one
to tell; but I have never so seen it, and have always looked upon the eye
as a deceitful member--very.