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

1 As an electrical conductor. well bs:rnt
charcoal ranks next to the metals. Me-
talic ores come next to charcoal. Wa
ter and moist earth. which are so fire.
lquently recommended as terminals for
lightning rods, are among the poorest
of conductors.
L One Of the best protected buildings
that we have heard of is that of Mr..
John Knox Smith, an intelligent Eng
hsh merchant residing at Singapore
His country house is built on q prom
inence, upon bed Of iron ore, with
which the house lightning rods are made
conAnuni4te. The lower ends Of the
i!c1 Tim hess :; ;sszy es1ensive eondnc-
ling surface, and the prot9cticn allcFded
is considered perfect. Thunderstorm
and lightning strokes are very frequent,
but the house has never been injured.
1t was supposed to have been estab-
lished by Charles and Gay Lussac that
a lightning rod protected an area whose
radius was double the hight of the rod
extending above the building, but this
rule is not longer reliable by reason of
the extensive use of metals in the shape
of pipes, ect., in the construction of the
buildings of our day.
When electricity finds several paths
to the ground, it will prefer the best,
it is true; but some portion viii also
pass along the poorer conductors. If,
Therefore, any metallic substances lie
within the area supposed to be protec-
ted, they are in danger of being struck
This is especially true where the light
ming has a chance to jump to the gas
and water pipes of building. 1t is a
good plan to connect these pipes with
the lightning rod; if the rod is struck.
the electricity win then have an excel
lent path into the ground and viii be
rapidly diffused over the vast under
ground network of pipes. The danger
to the inmates of the house of being
struck from the pipes is less than that
of receiving shock from the powerful
induced currents, liable to be developed
in them, if urconnected, during thun-
de-s.orm.
The more rods on building the bet
. ter, especially if all are connected with
each other near their upper ends.
Multiple lightning conductors are
useful because each one helps the other,
and if the discharge is too great for one,
they will be able to carry it between
them, but what is more Important is
this The less the total resistance of
the conductor to earth, the more certain
is it that no other, undesirable lire will
offer an approximately good path to
the earth, and so get part Of the fash.
Thus, suppose single rod whose resis-
tance is l, and that a series of bolts,
hinges, cutters, stove pipes, etc, offer
another line passing perhaps through
the walls of the house or the body OF
its occupant) whose resistanceis Now,
under these conditions, fash would
be likely to divide itself, and while
would go safely down the rod, pass
ing along the other line might burn
the house or kill the man. But if two
rods were connected, the resistance in
this line would be but half, hence f.
would take this road and but Is tend
to go by the other. Again, the less the re.
sistance of any line, the higher the op.
posite charge developed in it by induc.
ton, and hence the greater its attrac.
tive influence, lea ling the discharge tc
prefer it as path. This bears upon
the Importance Of connecting all acci.
dental lines of conductors. such as Gas
and water pipes, with the lightning
rods. Insulated, these ere oppositions
lines. soliciting the lightning to come
into house and traverse them; connected
they help the rod as we have seen &c
get and keep the lightning outside.
Finally, in the way of general advice
we would say Connect all your light.
ming rods together, and also to your
iroE tank, and water, gas, or Other
pipes. not by separate connections, but
so that there is some connection between
all, which connection should be as hiGI
up as possible. If you have a metal
roof, connect all rods with it. If the
roof is not Of metal. then connect vonr
rods together by means Of good sized
conductor running along The ridge Of ht
roof. Bear in mind that. to carry of
the heaviest lightning fash known, a
copper rod one inch in diameter is no;
considered too large; and though oi
: course such flashes are Of very rare &C.
currence, they may come. Hence the
great value of uniting your differen.