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

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wise is Il source of danger, bccames
an obsolute protection, even to
persons or animals shcltcring beneath
IT, Or course nobody would suggest
that all trees should be thus dealt
with, but it often happens tha, from
It's special POSITION tree during
thunderstorm is not only source of
some peril but is the occasion of much
uneasiness and anxiety.
According to the liyhtnin" rod com
Terence appointed Il few years 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 solid
iron rod. On the newest Of our public
bulldlnes- such us the new Law
Courts, where il may be assumed they
would act on the best professional ad-
vice, they have adopted flat bands of
copper. These are made in sizes
varying from Il sixteenth TO an eighth
of an inch thick and from three quar-
tcrS 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 Il building than thick
rod. But the iron makes Il very salts
factory lightning rod, and provided
1t is quite continuous and embedded
we'll into the earth, going down, if
possible, into moist stratum Of soil,
it affords perfect security.
The cost of such rod up a house
or the main trunk Of tree 10 hcilyht
a little beyond that Of surrounding
objects is really very trifliny.
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 harmleSsly to earth an actu-
al discharge Of lightning. but NAV al
so prevent the occurrence Of the flash
by conducting the electricity in sill
cnt stream so to speak. For this pll-
pose electricians now recognize the
fact that it is important that the con-
ductor shall terminate in 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 prevcntin" corrosion.
When ii is practicable to do so. they
should be periodically examined, and
should be rcpointed when they are
found to have rlstcd away.
The notion prevalent at one time
that conductor should terminate in
a ball is quite abandoned. and 50 also
Is the idea that a tube is better than
a solid rod. II used to be Thought
that electricity passed only by the
surface of the conductor. and as
tube presented more surface than
solid rod the tube was for a while
the favorite form. This is now known
to have been mistake.
1t is true that electricity al rest
distributes itself over the surface rf
conductor, but when in motion if
passes through the whole mass, and
the efficiency of metal rod of any
given kind is to be gaugcd by its see
tlona' area, only, as it has been said,
that sectional area must terminate in
a point. the finer the better.
Without the point ii will carry the
most violent discharge TO carth-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 clcc-
tnclty may rush without any violent
explosion at all.
The Meteorological Journal for
1919 relates a very curious illustra-
ton OF this action of conductors. 4
party Of tourists in the F,ngadinc had
attained height Of about II 900 feet
above the level of the sea when they
Found themselves cnvcloncd in mist
and Falling snow and in silence brok-
en- only by a curious intermittent
noise which thcy presently traced to a
flagstaff ON the mountain peak. The
noise rcscmblrd the rattIing Of hail
stones on a window, and close scru-
tiny convinced them that it was due
to the PASSAGE of current Of clcctri-
city through thc pointed fla" staff.
AT one moment the rattling was AT
the top of the staff, at another at
tie bottom and al other times is
qmvercd seemingly all through il, but
never for a moment crasr6 Tho nor-