Green-Mountain freeman. [volume] (Montpelier, Vt.) 1844-1884, 1852-02-26

urge COlumnO OF VapOr passing upward from the
barn, and presenting to the over-charged cloud,
a large blunt point of attraction. This column
reaches an altitude much higher than any light
ming rod can do. 1t is a very powerful attractor
of electricity. This may also be illustrated by
holding the mouth within a couple of inches Of
the prime conductor of an electrical machine.
and breathing upon the conductor, which will
Immediately discharge it, insensibly to the op
erator) Hence, as the cloud arrives over the
barn, with its load of electricity, the column Of
vapor being the nearest object Of attraction,
causes an explosion, or streaks of lightning. If
this column could have been prepared with
sharp metallic point, it would have discharged
the cloud without an explosion. In this connec-
ton it becomes important to observe that the
grain and hay should be made as dry as possible
before it is placed in the barn or large stacks,
If it were perfectly dry, the barn would be in no
more danger from lightning than any other bull
ding.
The above theory applies with equal force to
all cities and villages. 1t is believed that one
hundred lightning rods, properly arranged, land
Of this we will speak presently would effect
ualIy protect the whole city of New York against
Lightning. Suppose such should be erected on
Long Island, the heights of Brooklyn, # Hobo
ken, on all elevated places around the northern
surbubs, at suituble distances and throughout the
city, especially upon all high buildings, steeples,
towers, &c.? If such were done do not see
how it is possible for any house in that city, or
anything else to be struck by lightning, because
every cloud, when from whatever quarter it
might approach, would be effectnay deprived
of all superabundant electricity before it could
reach the city. These rods would not only form
mediums for equalizing the electricity in the
case of overcharged clouds, when the earth IS
in the condition of a negative to the positive
cloud, but in the reverse condition, when the
earth is positive and the atmosphere Or cloud,
negative. They would form conductors equally
as we'll one way as the other. know of no
outlay that city or village could make, that
would be more judicious than this, and the far
mer, certainly, cannot safely dispense with it,
But the position of the rods is not the only point
of Importance The manner of their arrange
nent is essentially The point of greatest mo-
ment and we will now proceed to discuss
that.
A lightning od,-lts material and manne. Of
construction, is the simplest thing in nature Oh
I A,o ornoiDla
which it acts. The earth is large body, al
ways charged with electricity Some hav'
: called it a generating battery. The atmosphere
and its vapors or clouds, is also large body o
: matter always charged with electricity. But
owing to their different densities and compost
tions these two bodies are always in .iiferen
l.. states Of electrical condition. Sometimes tht
earth is more highly charged than the atmos
l phere, but this is rare. Very often the atmos
phere IS more highly charged than the earth
Whenever either Of these relations exist, thert
: must necessarily be non-conductng medium
between the earth and the atmosphere, or at leas
stratum Of nearly perfect anhydrous or dry at
f mosphere. Now, to equalize the electricity o
: the earth and the atmosphere, we have only tt
4 form medium, through or over which the sur
: plus electricity of the one may pass 10 the other
= Doctor Franklin discovered how this might b,
= effected.
;, He raised simple kite, armed with metai
d points, and fastened to the earth by wire Thi
# brought the lightning from the clouds Thi
: disarmed the clouds of their lightning. Th
It metal Of the kite attracted the electricity Of tn
cloud the sharp points divided its current, so tha
!. it passed down the wire harmlessly. This wa
the first lightning rod, and illustrates the primo
e pie upon which it acts, viz: continuous me
$ tallic medium from the earth to the cloud, G
T. near it, Now, a perfect lightning rod mus
:. therefore, be connected with the earth perfedh
!, and ascend as near as may be to the cloud, wit
u perfectly sharp point. A perfect conneco
= with the earth can he effected by sinking tn
e over end of the rod to depth that will ensul
: perfect and perpetual moisture. In some situt
e tons ten or fifteen feet deep will be required,
t.. others four or five will be sufficient owing
the different constituents Of the earth at the pac
o It would never be safe to allow the lower end
g rod to rest in a sand bed that must be passC
through, though an hundred feet were penetr
y ted. When situation Of permanent and pc
of petual moisture is obtained, that Is the depth
sink the lower end And even then, a few ft
is square of copper sheeting should be soidercd
IN the end of the rod. Some require deposito
~ puverzed charcoal to be placed at the botto
d. in which The end OF the rod is to rest. | wOt
~ recommend, if charcoal is to be used al
IL which do not consider necessary, that it be m
o. ed intimately with the earth at The bottom,
by will serve to retain moisture in very dry seaso
he The rod must be single continuous rod,
cd round iron, three-eghts to half an inch dlamet
he # must be so long that it will reach from
ly leep insertion in the earth to the highest po
it above the building at which it can be sustain
re- 1t should be carried up within six inches,
,re less than four inches, of the house, and must
he supported by some mont conducting substance
is the course of its ascent, such as horn or glass
of It should not be placed near nails or spikes, t
ID is no nails or spikes should be in the house
ng rectly behind the rod. Its upper end must
va brought to perfectly sharp point. This is
of the utmost Importance, because the sharper
,ns more easily will the fluid be divided by it,
I'm. ,his connection it must be borne in mind tina
nth is the division of the current by the sharp pc
ing that prevents the shock and that it is the
on. septation Of an obtuse or blunt surface that
ma dnces il. Bear in mind, also, that it IS the
low terrupton of the current in all cases OF elect
the itv, that causes shocks. The sharp point ave
ght- this. and hence, as has been shown in prev