New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1874-07-23

| /, VI, y most other modern discoveries. The
ornore,, of lightning rods can cite instances
where thew }. oiled to protect buildings where,
uerbons there ,,rOuld have been no lightning
stroke if q rod nd not attracted it. Sand
TO oppose to this line o. argument, there is no
record of the buildings that are saved by
lightning rods. and there cannot he. For it is
not to be questioned that in large proportion
of cases, the conductive power of the rod
serves to relieve superfluous electrical tension
without the violent discharge which we
recognize az the lightning stroke. Where con-
ductors are abundant, lightning strokes are
rare, and hence no dOubt their marked infre-
quency in cities, where every chimney with It's
column of heated air adds its quota to the
abundance of points of attraction for electricity,
while networks of non rails upon the streets
and iron tubes beneath them assist IN diSsl-
pating the discharge.
There are however, certain statistics in
point. In Germany there are insurance
companies that provide especially against
loss by lightning, and the testimony OF
their collected data is conclusively in favor
Of the protection afforded By lightning rods.
One of the most remarkable results or
tner Investigations, backed by an abund-
ant compilation of instances is that the ire
quency of damage by fire is materially les
sened by the presence of any non-lhIAnlmaOic
material to receive the first onset OF the stroke
The lightning seems to lose, In the instant OF
striking, its power to infame; or rather IL eX-
pends this power on the point first struck, and
in its subsequent course it rarely sets fire even
TO most inhammable roofs and buildings. The
denser the body first struck and the greater
its conductive capacity, the more Is the light
ming robbed of its power to intlame; and thus
a mere iron knob on the highest part OF
building has served for the protection of an
exceedingly cOmbustble roof.
But perhaps the most valuable information
on this subject was collated by the English
Association of Telegraph Engineers. After
long and disastrous experience in the frequency
with which telegraph poles were struck by
lightning, the English companies adopted
measures that resulted in perfect security
from this kind of damage to their property.
To each pole they have attached No. wire,
running from the upper end to the ground.
They state that it is chiefly necessary that
these conductors should be continuous; that
there should be no JOINT unless well sOldered
and chain-linl rods, braided wire rope, and
tubing are not as etlcacious as the simple
No wire. The Secretary of the Association
referred to, Mr.. Preece, has suggested further
points of Importance in attaching lightning
rods to dwellings. The underground connec-
ton, where practicable, should be made with
some large mass of metal, such as gas or
water pipes or else with deep, solid earth.
1t is evident that the latter requisite can
usually be best attained, out of cities, by
carrying the rod underground to suitable
distance from the building, into earth that is
permanently compacted by natural moisture.
Each conductor, if there be more than one,
should have q separate ground connection /;
but they should also be connected together,
and with a metal roof or any other mass OF
metal in their neighbOrhood. There should be
no points or acute angles in the conductor /;
the straightcr it is the better, as electricity
will follow Che line of least resistance and
greatest directness. Insulation, with such
conductor, is regarded as unnecessary.
Among other instructive suggestions from
this source is the estimate that the area
protected by the conductor is equal to
its hight above the ground; that the
upper part of the rod should termi-
nate in a gided or polished point; and
that lightning conductors require periodical
examination to keep them in good order. 1t
is stated as ali established fact that chimney
with thick layer of SCOT and an ascending
current of hot air is an excellent conductor
that is if you want the lightning brought into
the house. With facts like the foregoing be-
fore us it is not difficult to understand the
occasion of the recent disaster at WeehaWken,
where the ascending column of vapor from
the oil tanks probably served as a conductor,
and the oil, struck before the fluid reached
the iron of the tank, burst into destructive
flame.