The herald and news. [volume] (Newberry S.C.) 1903-1937, 1907-08-13

up the tree there would be no such
Nef!"ction. The metal conductor
would afford Il readier 'a>sage than
the body oi a man nr tie materials
OF house, and the tree. which other
wise is a source Of danger, becames
an obsolute protection, even to
persons or animals sheltering beneath
it. Of course nobody would suggest
that all trees should be thus dealt
with, but it often happens that from
its special position tree during
thunderstorm is not only source Of
some peril but is the occasion Of much
uneasiness and anxiety.
According to the lightning rod con-
ference appointed a few Eears ago by
the Meteorological society Of London
to inquire into the subject and report
on the best form of the thing there Is
nothing much better than a solid
iron rod. On the newest Of our public
buildings. such as the new Law
Courts. where it may be assumed they
would act On the best professional adj
vice, they have adopted flat bands OF
copper. These are made in sizes
varying from a sixteenth to an eighth
of an inch thick and from three quar-
ters Of an inch to two or three inches
wide. The copper is somewhat bet
ter conductor than iron, and the flat
bands adapt themselves more easily
to the walls Of building than thick
rod. But the iron makes a very salts
factory lightning rod. and provided
it is quite continuous and embedded
we'll into the earth, going down, It
possible, into a moist stratum Of soil,
it affords perfect security.
The cost of such a rod up a house
or the main trunk Of tree to height
a little beyond that Of surrounding
objects is really very trifling.
Many persons who are we'll aware
of the protective power OF a good
lightning rod are not perhaps equally
we'll aware that it may serve not only
to direct harmiessly to earth an actu-
al discharge Of lightning, but may al
so prevent the occurrence Of the flash
by conducting the electricity in a sill
ent stream so to speak. For this pur-
pose electricians now recognize the
fact that it is important that the con-
ductor shall terminate in a sharp
point, indeed the most approved form
of lightning rod now has a corona OF
points. and a practical difficulty is to
keep these terminals sufficiently
pointed by preventing corrosion.
When it is practicable to do so, they
should be periodically examined, and
should be repointed when they are
found to have rusted away.
The notion prevalent at one time
that a conductor should terminate in
ball is quite abandoned, and so also
is the idea that a tube is better than
a solid rod. It used to be thought
that electricity passed only by the
surface Of the CONDUCTOR. and as a
tube presented more surface than a
solid rod the tube was for a while
the favorite form. This is now known
to have been a mistake.
It is true that electricity at rest
distributes itself over the surface Of
a conductor, but when in motion 1t
passes through the whole mass, and
the efficiency of a metal rod of any
given kind is. to be gagged by its Sec
tional area, only, as it has been said,
that sectional area must terminate in
a point, the finer the better.
Without the point it will carry the
most violent discharge to earth-or'
as, Of course, it sometimes happens,
from the earth to the clouds-if the
rod or band be sufficiently thick, but
with the point it may act as a sort of
spout or pipe through which the elec-
tricity may rush without any violent
explosion at all.
The Meteorological Journal for
1875 relates a very curious illustra-
tion of this action Of conductors. A
party of tourists in the Engadine had
attained a height Of about II 900 feet
above the level Of the sea when they
found themselves enveloped in mist
and falling snow and in silence brok-
en- only by a curious intermittent
noise which they presently traced to a
flagstaff on the mountain peak. The
noise resembled the rattling OF hail
stones on window, and close scru-