Bismarck daily tribune. [volume] (Bismarck, Dakota [N.D.]) 1881-1916, 1911-06-15
Japanese Tea Gardens
LIGHTNING PROTECTION.
BY e. S. keene, Professor Of
Physics and Mechanical
Engineering.

1
Protection from lightning is sui
ject that recurs with the coming {
each springtime. In the violence {
the atmospheric electric disturbance
accompanied by the awe-inspirin
flashes of the lightning so commo
with the thunderstorms of the north
west, there are few who have not DE-
sired the protection of a lightnin
proof shelter, --~ ,--
The probability of an individual
building being struck by lightning il
really very slight but there is Away
a possibility of such an occurrence,
and also that the stroke might be at
tended with considerable violence, ant
more than that the building might take
fire.
That lightning rods are, real pro
lection to the buildings from lightning
has been proven so many times that
their value is no longer questioned
but the possibility of obtaining ex.
detrimental data is so limited that def
mite rules of the establishment of
the rods and conductors have never
been formulated. For many years,
lightning rods were looked upon with
suspicion in this country, because
their sale for a considerable period
was used as means to defraud the
unWary.
The formation of lightning is very
|imperfectly understood but experience
with its vagaries and knowledge of
the laws of high-tension electric cur
rents has established fairly good I'M
derstanding of the methods of con-
structing lightning conductors for all
ordinary discharges. 1t is very we'll
known that lightning is the discharge
Of large amount Of electricity in a
very short space of time and that
whatever affords it a passage to the
earth is apt to be badly damaged, un.
less the vehicle happens to be good
conductor of electricity and of SUI
ficient size to transmit the amount of
electric energy the flash contains; in
which case it passes AWAY doing no
damage at all: =! "
AS a storm develops the electrically
charged clouds pass over the earth
and when the electrical intensity be-
comes great enough to break down the
resistance 81 the intervening air, the
resulting discharge will pass into the
earth by the most convenient path.
This Is commonly some high object
of the landscape, a building a pole,
a tree or any other object that ex-
tends up from the earth. If the OBJ
ject is conductor of electricity and
connected to the earth, the lightning
will pass into the ground without any
damage being done, but if it is not a
good conductor, the havoc that is
wrought in an instant is sometimes
appalling.
Buildings with metallic roofs that
are properly connected with the earth
are far better protectors from light
ming than could be given by rods.
Buildings that are completely covered
with sheet metal and we'll connected
with the earth are practically light
ming proof. Covered In this manner,
the buildings have been known to be
repeatedly struck by lightning with
out the least damage. The sheet iron
grainery, so common in the west, when
we'll connected with the earth, may be
considered lightning proof. The
may be made of metallic rods that
extend we'll into the earth and are
securely fastened to the metallic GOV,
ering of the buildings.
In considering the form of light
ming conductors 1t is we'll to keep in
mind that fact that a metal covered
building we'll connected with the earth
is practically lightning proof and
that one with a metallic roof, we'll
grounded is excellently we'll protected
if not perfectly safe. If then, the
roof of building possesses metal
lie ridge, eve.troughs and down spouts
these will afford very good protection
Iif they are we'll connected and well
grounded. A roof covered with &
metallic screen, as chicken screen
makes an excellent protector wher
properly grounded.
1t must be remembered that the
Esity and too much care cannot be ex
Fercised in it's construction. The eartf
is the great reservoir Of electrical en-
ergy and it is always at zero potential
If a discharge of lightning can be di
rected into the moist earth by con
ductor, it's energy is soon dissipatet
but the ground connection must b.
of considerable area and extend wei
Into the moist EARTH. A piece o.
galvanized iron pipe driven into thu
ground seven or eight feet makes 9
good ground" Large buildings must
have two or more such grounds"
The connecting wires must be secure
ly fastened to the ground connections
In the matter of conducting wires
the United States weather bureau
lin a bulletin on lightning and light
lining protection recommends number
three, galvanized iron wire Drown &
Sharp gauge) as amply sumcient in
Eize for ordinary lightning protection
If metallic downspouts are used as
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