Evening star. [volume] (Washington, D.C.) 1854-1972, 1873-05-10
LIGHTNING RODS.

The experience of a century has concluSiyely
shown that gooa ,, ngtning rod, properly placed
Ills it, purpose. On the other hand, lightn ng
rods eaTelessly constructed, unscientiicaliy
arranged, are not only useless, but actually in
wife destruction upon what they profess TO pro-
tect. The lightning-rod fulfllS two essentially
different ofices-it acts both hylaetic and
rsmedy; il is intended TO prevent, if possible,
the lightning from striking, and, if not, to make
its striking more harmless. The first object il
attains, in most cases, by silently dscharging
the threatening cloud, gradually drawing on its
electricity, and so disarming it; the other, by
furnishing free a passage to the earth that
when cloud, too heavily charged, and too
swift in its approach for cOaxing, does pour out
its wrath. the lightning will pass off harmessIy:
for il does damage only when its course Is OBJ
structed. For the purpose OF prsreH.iHg light
one, if only it is well elevated above the highest
part of the building, and is provided with
sharp point gilded or tipped with platinum.
There Is patent "magnetic point" which is
a very good one and well made, though the
magnetism is simple quackeTy and of no use
whatever: III such point, properly placed, is
connected thoroughly TO the ground by the con-
ductOr no larger than ordinary telegraph
wire, ii viii silently discharge nine out of ten
of all the thunder-clouds that come within its
range; the tenth, however, will very likely be
too strongly charged and approach too rapidly
in which case the rod will be struck and melted
and the building damaged or destroyed.
Security against such a catastrophe requires
that the rod, If of iron, should be not less than
three-quarters of an inch in diameter. ian inch
Il better OF, if of copper, from tive-sixteenths
TO One-half an inch; the iron rod should weigh
at least i've pounds to the yard, and the copper,
one. Ii makes very little difference what the
formOf the conductor may be, whether round or
square, or in fiat sheets, though there is a slight
advantage in causing 1t to expose considerable
surface, since when powerful currents are
passed through wire its central filaments do
not perform quite their due proportion OF the
work. 1t is not true, however, as many light
ning-rOd makers assert that only the surface of
the rod Is efiicscious. The Ightning-Tod ought
n - 10Th ont nri Snfr, tf,a
joints should be so carefully made as to render
the continuity virtually perfect; otherwise.
when lightning strikes great amount OF heat
~ developed at the joints, and the building
may be fired or the rod melted. The wire ropes
that are now much used as lightning conduc-
tors admirably fulfill this condition of con-
unuity, and when large enough are as good as
anything can be; several of small diameter, of
course, give the same protection as a single
large one, and in some respects are better.
Where houses are provided with metallic
water-sPouts, these ought to be included in the
conducting chain; if they are not, they are
really dangerous, the danger being that a por-
ton OF the discharge will leap from the rod to
the gutter upon the roof, doing damage there
and then following the spout, again produce a
dangerous discharge in the passing ground
The rod. therefore, should be carefully cor
nected with the roof gutter, and the terminal of
the water-spout with the ground. 1t the rod at
any point OF its course passes near "a. c. within
three four fect) OF the gas or water pines il
should be connected with them at the remotest
point from the ground where the approach oc-
water pipes, If it comes near them both. Ii this
precautiOn Is neglected the building will almost
certainly be fired by the lightning striking from
the rod to the pipe through the wall. More
than a dozen accidents of this kind have hap
pened during the year. But the most danger
ous, and at the same time most common, defect
of lightning rod, lies in an insufficient connec-
ton with the ground. Earth, even when moist.
is so poor a conductor of electricity that the
conditions Of security can be fulfilled only by
giving vastly greater surface of contact be-
tween the rod and the soil than is usual: indeed
the proper arrangement of matters at the lower
pense than all the rest, and is very seldom
thoroughly done The rod should be carried hori-
zontally foot or two under the surface to q
distance of eight or ten feet from the foundation
walls. Here pit should be dug four or five
feet square, penetrating to moist earth. Garry
the rod down the centre of this pit to the bot
tom, and throw in cart-ioad of scraps Of
sheet-iron and tin, and you will accomplish the
end as wei and cheapfy as in any manner we
know of. cart-load or charcoal VIII answer
the same purpose. There is also q patent ground
connection for advantageous, which Is very
good, consisting Of circular disks of iron, cast
with numerous spikes and projections, so far as
to expose a large surface. These disks each
about a foot and a half in diameter, and per-
forated in the centre, are strung along the un-
dergIound portion of the rod at the distance of
foot or two from each other. -Four or five of
them are sufficient, if the soil Is moist.
After the rod is once thoroughly put up it
will require no further attention, except ocea-
sional examination at the point where it enters
and If Il becomes seriously corroded must be
repaired. Considering the expense of putting
up thoroughly protective rod, il is certainly
fair question whether in locations not extra
tent oneself with rod designed simply As a
preventive, and leave the insurance COMPANIES
10 meet the greater but rareI risky T.
Tunes.