The Democratic advocate. [volume] (Westminster, Md.) 1865-1972, 1872-08-03
Scientific
From the Scientific american.
Lightning Rods.

Lightning Rods.
Lightning Rods and how to con-
struct them" is the title ola convenient
little handbook by Professor John Phiu.
1t contains much useful information
upon the subject, aud ought to have
very wide circulation. The following
selections will give some idea of the
excellent character of the book:
Are Lightning Rods Really Protec.
ton There are many instances on
record where buildings protected by
rods have been struck and injured.
But this is not to be wondered at when
We reflect that fully one-half-uay, per-
haps three.fourths-of all the rods now
actually erected violate ibe iundnment-
al principles upon which their efficiency
depends. Besides serious errors 10 re.
gard to arrangement and continuity, il
will in general be found that it is only
by the merest accident that a good
ground connection is ever secured
This point will be more fully discussed
in subsequent paragraph. Meanwhile,
the following facts prove irrefragibly
the great value Of well constructed rods
The Cathedral Of St. Peter, 10 Geneva,
although so elevated as to be above all
other buildings in the neighborhood,
has for three centuries enjoyed perfect
immunity from damage by lightning /;
while the towerO St. Gervaise, although
much lower, has been frequently struck
This doubtless arises from the fact that
all the towers Of St. Peter are accident.
ally furnished with perfect conduction.
The great column Of London known as
the Monument, erected in 1877 in COM
memoratiou Of the great FIRE, although
over two hundred feet in height, has
never been struck while much lower
buildings in the vicinity have not es
capped The Monument, however, is
protected by most perfect conductor,
the upper end terminating 10 vase
from which proceed numerous metal
plates designed to initiate the appear.
auce Of tongues Of fame The vase
communicates by means Of stout bars Of
iron with the metal staircase, which
dcscends through the middle of the
column aud terminates in the ground.
\ still more striking instance Of the
value Of lightning rods is a church on
the estate OF Count Orsini, in 0orinthia
This building was placed upon an emf.
neuee, aud had been SO often struck By
lightning that it was deemed no longer
safe to celebrate Divine service within
its walls In 1880, a single stroke ol
lightning destroyed the entire stecple
after it had been rebuilt, it was struck
on an average four or five times year
without counting extraordinary storms
during which it was struck from five tC
ten times 10 a single day, In l77S, tht
building was reconstructed and furnish
ed with conductor; aud according tC
Liehtenberg, up to 17S3-that is to say
during the space of five years-thc
steeple had been struck only once, and
this stroke had fallen upon the metallic
point without producing any damage
For two or three years after its erection
the church OF st. Michael in Charles
town had been frequently damaged By
lightning; conductor was attached
to 1t, aud during the following four
teen years it had not been injured -
The steeple Of st. Marks, in Venice
has hight OF $40 feet, aud was FIRE
quertly struck by lightning until 1
proper Lightning rod was applied to it
since which time 1t has not been iDjur
ed These facts leave no room fci
doubt in regard to the great value o
lightning rods.
Tie Best Form for The Rod.-Ir W,
examine the rods ordinarily found il
market, and pulled by those who hay,
invented them, we shall find that in
stead of being solid bars of sonare
round or merely faltend form, thew ar,
tubes. twisted ribbons or bars who's,
cross section has the form of n STAR
And if we ask WHY these connlicate,
aud expensive forms have been ndon,ed
we shall be told that il is far the npr
pose of obtaining the greatest amoun
Of surface with the least amount of met
al, and this is done because oleetricit,
always resides on the surface Thos,
who reason in this way. however nrov,
clearly that thew have meyer s,ud;ad N,
subject. else thew wonld be aware M,
fact that while static electricity as il /;
called-tbat is electricitv at rss,.I
ways disposes Itself on ihe snrr,oo .
bodies charged with il eloc,ricity !,
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