m may be taking place at some distance from the
point of observation. The electrified cloud induces the opposite charge
beneath it, the similar charge being repelled. It is noticeable that the
needle of a galvanometer, starting from the middle position, goes
gradually over to one side, eventually indicating a considerable
deflection. Suddenly, owing apparently to a lightning discharge some
distance away, the force which caused the deflection is withdrawn, and the
needle rebounds with great violence to the opposite side. In a short time,
the cloud becoming again charged on its under surface, and recommencing
its inductive effect upon the adjacent earth, the needle starts again, and
goes through the same series of movements, a violent counterthrow
following every flash of lightning.

If we can so far control our imagination, we may conceive the earth to be
one large insulated conductor, susceptible to every influence around it.
If then the earth, as a mass of matter, behaves as above indicated, there
is no plausible reason for declining to regard any other large conducting
mass in a similar light, and as a body capable of being subjected more or
less completely to the various impulses affecting the earth. In other
words, a large mass of conducting material, partially or perfectly
insulated, is, during a thunderstorm, in considerable danger. With this
portion of the subject I shall, however, deal more fully when discussing
the merits of lightning protectors.

Lightning discharges do not take place between cloud and earth only, but
also, and perhaps more frequently, between too oppositely charged clouds.
We then get atmospheric lightning, the flash often extending for miles.
This form of lightning is harmless, and in all probability what we see is
only a reflection of the discharge. The oft-told tale of the lightning
flying in at the window, across the room, and out of the door, or up the
chimney, is all moonshine, and before dealing with lightning protectors I
intend to expose some of the fallacies concerning lightning. Were the
discharge to pass through a house, it would infallibly leave more decided
traces and do more damage than simply scaring a superstitious old lady now
and again. Many people are often and unnecessarily frightened during a
thunderstorm, but it may be safely predicted that a person under a roof is
infinitely safer than one who is standing alone on level ground, and
making himself a prominence inviting