Saint Mary's beacon. [volume] (Leonard Town, Md.) 1867-1983, 1874-11-05


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- ! iIirstninc etoru. foruerlv .ba.,er.s
I'd d.,trovea NOR, s. lr,. Of our nole.
~ whirh .re nov fullv protected bv ,
runductor (No. 8 v;yel pl.ced ON every
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NJ, IN daunce /. prevented. Where
- poles are mot provided with rods
Image eupnes.s 2.Fs
8 According to the best authorities. q
Rer rod e one inch u diameter, o.
keopPer xnaG .1ns
other form. wiH resist the dnact Of any
discharge OF lightning hitherto expe-
renced. The copper rod is therefore
the safest and best material that can
be used, but it is expensive. Iron rods
OF one inch In diameter are very COM
monty used, and, If pointed with solid
copper and properly put up are efica-
aous In the great majority OF cases.
The particufr torm OF the rod make:
no dlfferen2 1t may be round OF
square, t + or hollow, composed oi
one soy Ipiece or made OF wires twisted
togetE' 1t the quantity OF meta
contained IN the cross section OF the rod
that is of value, not the form.
The reason for terminating lightning
rods in point is as follows When g
thunder cloud highly charged with pos
tive electricity comes up, it repels tn,
positive electricity of all bodies on Tho
surface of the earth coming within it,
influence, and causes negative electrici
ty to accumulate in them. This is called
induction, and it always takes place be
fore discharge. Now it has been dis
covered that when electricity is accumu
lated in a body in this manner, it CT,
most readily escape by sharp points be
cause in them it meets with the leas
resistance. A lighted candle held neal
the prime conductor of an electrical ma
chine furnished with a point will /,
nearly blown out by the current of ali
produced by the escape of the electrici
ty. Lightning rods are therefore pro
vided with sharp points to allow the ac
cumu!ated negative fluid to pass of
readily into the air and neutralize tn,
positive flaid of the thunder cloud.
The object being to make so good ,
passage for the lightning to the g-ount
as to remove all danger of its leapinc t,
some conductor in the house, the great
est care must be taken not to have an,
break in the conductivity. As it is in
convenient to manufacture or transpor
the rods in one piece, the differen
parts must be in intimate connectio,
when they are put up: it is best to bav,
them soldered and the joints protected
from the air and moisture.
Tn point of the rod should be exten
ded little above the chimney or high
est part of the building. and should b,
fastened IN contact with the building
by staples or clcats. Glass insulator.
should not be employed. 1t make.
no diiference IN conductivity whether
the rod Is painted or not painted.
No building can be said to be proper
ly rodded or protected against light
ming, unless the lower part of the roc
or terminal under the ground is mad,
quite extensive. The extremity of tn.
rod should connect with masses Of goot
conducting materials, such as old iron
or iron ore, or coke, or charcoal, laid il
trenches. or the rod itself should b,
elongated, sunk deep in the ground. an,
carried a considerable distance from III,