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Vol. LXX. No. 4112. NEW YORK, AUGUST^ weekly, $ 1.00 per year 
QUESTIONS ABOUT LIGHTNING RODS. 
What Rods? How Lightning Works; Protection. 
There is a great deal of controversy among the people 
of this locality of late regarding the advisability of erect¬ 
ing lightning rods, and so I write for general information. 
Do you tl\ink it is best-to rod buildings, and, if so, what 
for? If iron will melt under voltage test at 7.5, steel at 
8.5, gold at 35, pure copper at 96, and silver at 100, 
which of these would you advise using? Will copper rods 
be more efficient than iron or steel of the same size, and. 
If so, how much more so? Are buildings surrounded by 
trees less liable to be struck than if standing in the open? 
Is it because of vapor rising from trees that lightning is 
attracted to them? Is this vapor charged with electric 
energy, and is the electricity in the clouds collected in 
this way? Why is it that the electricity striking a tree 
near a building often jumps onto the building instead of 
following the tree to the ground? Would a rod attract 
the surrounding ulectric energy and take with it the 
moisture, and distribute both in the atmosphere above the 
building so that there would be less attraction? Is any 
metal roof safe unless grounded? Ought points to be 
placed on the peaks of such roofs? Is any old rod good 
enough, and is a pure copper rod more desirable than 
others? Would you advise one to buy a good rod at an 
advanced price, or pay less and get less? I understand 
FIRST-CLASS PUl’lL AND- FRIEND. Fig. 317. 
that surface furnishes the important part, and, if so, how 
large would an iron or steel rod have to be to do as good 
and lasting work as a pure copper rod of three-inch diam¬ 
eter? s. E. L. 
Staatsburg, N. Y. 
The questions asked by S. E. L. cannot be answered 
catagorically. Much remains to be learned regard¬ 
ing the origin and behavior of atmospheric electricity 
in its intense manifestations in the form of lightning, 
so often destructive, especially in the open country. 
In some manner not yet well understood electric 
energy is generated in the atmosphere and accumu¬ 
lated locally under enormous strain or tension in the 
region of certain cloud forms, much as steam may 
be generated in a boiler or air may be compressed in 
a reservoir until the tension becomes very great. In 
either of these three cases, if the accumulation goes 
on, there comes a time when the surroundings give 
way and the pent-up energy spends its power in 
destructive work. 
“Is it best to rod buildings, and if so, what for?” 
If those interested with S. E. L. will pool their 
experience and list the number of farm buildings 
of which they have many years’ knowledge, and the 
number of instances among these where lightning is 
known to have done injury, they will have some basis 
for judgment as to the liability of farm buildings 
being struck by lightning. We can look back to the 
old farm home with its house and group of barns 
which have withstood all of the thunderstorms since 
1863 without rods and without injury. Likewise 
there are three other groups of buildings belonging 
to brothers and sisters, in the same neighborhood, 
that have similarly escaped injury through more than 
“WHEN WE WERE A COUPLE OF KIDS.” Fig. 318. 
30 years without protection. Nevertheless, during 
one electric storm of 10 minutes’ duration, five fires 
were kindled within sight of a brother’s house. There 
is no question regarding the danger to farm build¬ 
ings from lightning, but the number of buildings 
which are never injured in this way are very many, 
SHINGLING THE HUMAN ROOF. Fig. 319. 
to one which is, and each person must decide for 
himself whether he will take the risk without light¬ 
ning protection. 
Lightning conductors are designed for two pur¬ 
poses, first, to secure absolute safety against light¬ 
ning, and second, to minimize the injury or danger 
when the construction is not designed to afford abso¬ 
lute protection, against the most severe strokes which 
a building may receive. Theory, critical experiments 
and all experience thus far have led those best quali¬ 
fied to judge to believe that structures entirely encased 
in metal, like a barn with galvanized iron roof and 
sides, well grounded, are absolutely safe against injury 
from lightning. This judgment is based upon the fact 
that intense electrical charges always reside upon and 
travel along the outer surface of hollow conductors, 
and never side flash into the interior. It is also be¬ 
lieved that if a building is entirely encased in wire 
netting, well grounded, injury from lightning is nearly 
an impossibility. It is further believed, and with the 
best of foundation for the belief that any conductor 
leading from the moist earth near a building up to 
the roof affords the building protection to its full 
capacity, as a conductor and power to convert the 
electric energy passing along its surface into heat 
below a temperature capable of setting fire along 
its course. 
We may quote Sir Oliver Lodge, in answer to “If 
“THE WORKERS” READY" FOR BUSINESS. Fig. 320. 
iron will melt under voltage test at 7.5, steel at 8.5, 
gold at 35, pure copper at 96 and silver at 100, which 
of these would you advise using? Will copper rods 
be more efficient than iron or steel of the same size, 
and if so, how much more ?” He says: 
No longer will it be thought necessary to use a great 
thick conductor of inappreciable resistance; it will be per¬ 
ceived that very moderate thickness suffices to prevent fu¬ 
sion by simple current strength, and that excessive con¬ 
duction power is useless. * * * A thin iron wire is 
nearly as good as a thick copper rod, * * * an d a side 
flash from a thin iron wire is actually less likely to occur 
than from a stout copper rod. 
The fact that an iron wire, such as No. 5 or even No. 8, 
B. W. G., is electrically sufficient for all ordinary flashes 
and that resistance is not a thing to be objected to, ren¬ 
ders a reasonable amount of protection to a dwelling house 
much cheaper than when half-inch copper rod or tape was 
thought necessary. 
“Are buildings surrounded by trees less liable to be 
struck than if standing in the open? Is it because 
of vapor rising from trees that lightning is attracted 
to them?” In answer to these and the next ques¬ 
tion it may be said that the highest objects, especi¬ 
ally if they are conductors, are most likely to become 
paths for lightning discharge, for the reason that 
they make the depth of air, which is a non-conductor, 
between the ground and the electrified cloud, less 
and hence easier to break through. Besides this, air 
charged with invisible moisture is a better conductor 
