Year: 1874

that the efficacy Of the lightning rod
is no longer an open question and
that any failures are attributable to
Ja.nging or ignorant construction. 1t
would be au easy matter to multiply
statistics in proof of the assertion;
but none would carry with them
more force than the following state
ment obtained from the records of
TIE British navy, by Sir Snow Harris,
F. Il. S:


"l}etween 1901 and 1925, before
rods were introduced no less than
thirty five sail of the line and thirty
five frigatcs and smaller vessels were
completely disabled; and in 200 cases
recorded. 500 seamen were either
killed or injured. When the light
ming rod was introduced, every mast
was furnished with capacious con-
ductOr permanently fixed and con-
nected with bands of copper passing
through the sides of the ship under
the deck beams. and with large bolts
leading through the keel and keelson,
aud including, by other connections,
all the principal metallic masses en-
plOyed in the construction of the
hull" (Harris). Since the adoption
of this arrangement, ''it appears that
damage by lightning has positively
vanished from the records of the
navy"


In England. the various telegraph
companies suffered serious damages
by every thunderstorm, by the de-
structiOn by lightning of their poles
The poles are now provided with
small lightning rods. and all damages
has ceased.


In this country the Western Union
Telegraph Company has suffered in
the same manner, especially. says a
recent number of the Journal Of the
telegraph, upon the plain and
praires, where every lightning storm
formerly shattered and destroyed more
or less of our roles, but which are
now fully protected by a conductor
(No. 8 wire) placed on every fifth
pole, Wherever telegraph poles are
provided with such lightning rods,
all damage is prevented Where the
poles are not provided with rods.
damage ensues.


WHAT Is THE PROPER SIZE AND


MATERIAL FOR HOUSE LIGHTNING


RODS?


According to the best authorities,
a copper rod of one inch in diameter,
or all equa! quantity of copper under
any other form, will resist the effect
of any discharge of lightning hitherto
experienced. The copper rods is
therefore the safest AID best material
that can be used, blt it is expensive,
Iron rods of one inch in diameter
are very commonly used, and. if
pointed with solid copper and proper
Iy put up, are etflcacious in the great
majority Of cases. The particular
form OF the rod makes no difference.
1t may be roand Or square, twisted Or
hollow, composed of one solid piece
or made of wire twisted together. 1t
is the quaEtity of metal contained in
the cross section OF the rod that is of
value. not the form.


WHY SHOULD THE ROD BE POINTED !?


The reason for ter ninat ng lightning
rods III a point is as follows: When
thunder cloud highly charged with
positive electricity CONS up it repeals
the positive electricity Of all bodies
or the surface Of the earth coming
within it's influence, and causes
negative electricity to accumulate
i'll them. This is called induction,
and it always takes place before a
discharge. Now it has been discov-
cred that when electricity is accumu-
lated in body in this manner. it can
most readily escape by sharp points
because in them it meets with the
least resisteLce. A lighted candle
held near the prime conductor of an
electrical machine furnished with a
point will nearly blow out by the cur
rent of air produced By the escape of
:he electricity. lightning rods are
therefore provided with sharp points
TO allow the accumulated negative
fluid TO pass off readily into the air
and neuIralize the positive fluid o. the
thunder cloud,


HOW SHOULD RODS BE MADE AND


APPLIED?


The object being to make so good a
passage for the lightning to the grou d
as to remove all danger of its leaping
to some conductor in the house. the
greatest care must be taken not to
have any break in the conductivity.
As it is inconVenient to manufacture
or transport the rods in ore piece,
the different Larts must be in intimate
connection when they are put up;
it Is best to have them solGered and
the jo n protected from the air and
moisture.


The poirt of the rod should be
extended little above the chimney
or highest part of the building, and
should be fastened in contact with
the building by staples or cleats.
Glass insulators should not be en-
ploy ed. 1t makes no difference in
conductivitY whether the rod is
painted or not painted.


No building can be said to be
properly rodded or protected against
lightning, unless the lower part of
the rod or terminal under the ground
is made quite extensive. The ex-
tremity of the rod should connect
with masses of good conducting
materials, such as old iron. or iron
ore, or coke. or charcoal, laid in
trenches, or the rod itself should be
elongated. sunk deep in the ground,
and carried a considerable distance
from the house, and put in connection
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