The daily dispatch. [volume] (Richmond [Va.]) 1850-1884, 1870-07-04
I.trhtnfng Rods.

The essentials of good rod are that II
shan be we'll and firmly set, having points
above the highest portions Of the building,
and enough OF them to protect all the salient
places that it shall be solid to the ground,
or, If made in joints, firmly united. Ii
must be large enough 70 carry OF any pro.
bablc amount Of fluid falling upon 1t. Not
m IRE than two separate points should JOIN
one stem to the ground, and the lower ter,
minus must so far enough into the GROUND
to reach moist earth IL the ground end has
several branches, it is all the better; il
placed In a bed Of charcoal il is still better,
rs that is good conductor, and also pre-
vents rust to some extent.
The conducting power of copper Is toul
or five times that of iron, and that TACT mas
led to the manufacture Of light copper rodS,
which have not substance enough TO WIN
stand the heat, and so melt when severely
tested. Some manufacturers assert 'iia'
nothing better than a half-inch iron ROD mas
yet been devised, and that substance y y. ~
much needed rs surface to constitute ltSt-
class conducting ability:
1t is very uncertain. how large an area
rod of given height will protect. Diltcreht
French electricians have rated IL rs circu-
lar space of 4 radius from one to three Tunes
tho height of the rod above the highest part
OF that to which it is attached, but little
confidence can be placed in these conclu-
sions.
The electrical conditions of the atmos-
phere arc not uniform, and the discharges
may move so rs not to be influenced by q
rod. Discharges may occur laterally-Such
have been known to pass horizontally
through the atmosphere Il great distance
and strike with the most destructive flo-
lcnce Intervening or opposing objects. Ohc
mast Of ship has been struck, While an
other taller one. which had u rod attached,
was untouched. These facts, however, III
stead of furnishing arguments against rous'
only illustrates the Importance OF having
oil the exposed points protected.
By a great multiplication of conductors
the accumulation OF electricity is silently
disposed of; thus it is that houses in close
built cities, ships clustered at the wharves
large quantities Of iron in warehouses, etc.
etc, are seldom struck, because the cleo
trical equilibrium is maintained silently
If metal rod were extended from clou(
to the earth, no lightning would he seen
because the fluid would pass and repasS ant
the equilibrium be preserved. Clouds
passing low over cities lose their electricity
silently-by the church spires usually.
Isolated prominent objects arc most fire
quently struck. Single trees. detached
houses, barns, haystacks. and the like, SUI
fer oftencst. Practical men and rod manu-
facturers say that lightning strikes three
times rs often in the country as in town, il
proportion to the number of buildings, ant
that tcn'rods are used in the country to on
in the city, in proportion to the houses.
Ascending currents of irtrom chimneys
drafts of air through open windows am
doors, sharp edges and corners of elevated
= cornices, the "peak" of roof, or mai
protruding, furnish favorable points 70
lightning to drop upon under favoring cir
cumstances.
Metal stands to electricity simply in tn
Office of conductor. 1t furnishes rs natl
raj n channel for it to flow in as the bed q
river presents to water, and hence tn
utility Of lightning-rod is sclf-evident
Keep the points bright, the fastcnings insu
lated, the connections perfect, have it wei
set, avoid q small wire when Il good mass c
metal is needed, and an investment in Il TO
will be judicious one.
1t is also suggested that they be place
upon that side of q building from whic
thunder-storms most frequently approach
Buildings with high combustiblc stocks
very tall structures, or high flue stacks
should not be without lightning protectors
An ordinary fire policy covers losses fro1
fire caused by lightning. The mere shat
tering of house by wind, lightning, earth
quake, or any other violence, is not cOrcrc
by an insurance policy, but burning is
EuqlnecT.