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History of Lightning Rods
Lightning damage has been with humanity since people started
building structures. Early structures made of wood and stone tended
to be short and in valleys and as a result lightning hit rarely. As
buildings became taller, lightning became a significant threat.
Lightning can damage structures made of most materials (masonry,
wood, concrete and even steel) as the huge currents involved can
heat materials, and especially water to high temperatures causing
fire, loss of strength and explosions from superheated steam and
air.
Europe
Wooden church with lightning rods and grounding cables "Machina
meteorologica" invented by Václav Prokop Diviš worked like a
lightning rod.The church tower of many European cities, usually the
highest structure, was the building often hit by lightning. Early
on, Christian churches tried to prevent the occurrence of the
damaging effects of lightning by prayers. Priests prayed,
"temper the destruction of hail and cyclones and the force of
tempests and lightning; check hostile thunders and great winds; and
cast down the spirits of storms and the powers of the air."
Peter Ahlwardts ("Reasonable and Theological Considerations about
Thunder and Lightning", 1745) advised individuals seeking cover from
lightning to go anywhere except in or around a church. In Europe,
the lightning rod was independently invented by Václav Prokop Diviš
between 1750 to 1754.
Asia
According to some speculations, lightning conductors were used in
Nevyansk tower, where the roof of the tower is crowned with a
metallic rod in the shape of a gilded sphere with spikes. If the
Nevyansk Tower were built somewhere between 1725 and 1732, then the
Russian craftmen created the first lightning rod some 25 years
before Benjamin Franklin. Since nothing is known about the architect
or origin of the building (not even the time of construction is
clear), the true purpose and intent behind the metal rooftop remains
unknown.
United States
In the United States, the pointed lightning rod conductor, also
called a "lightning attractor" or "Franklin rod," was invented by
Benjamin Franklin in 1749 as part of his groundbreaking explorations
of electricity. Franklin speculated that, with an iron rod sharpened
to a point at the end,
"The electrical fire would, I think, be drawn out of a cloud
silently, before it could come near enough to strike [...]."
Franklin speculated about lightning rods for several years before
his reported kite experiment. This experiment, in fact, took place
because he was tired of waiting for Christ Church in Philadelphia to
be completed so he could place a lightning rod on top of it. There
was some resistance from churches who felt that it was defying
divine will to install these rods. For instance, in a 1755 sermon
titled "Earthquakes the Works of God and Tokens of His Just
Displeasure," the rector of Old South Church in Boston, Rev. Thomas
Prince, said:
"...the more points of Iron are erected round the Earth, to draw the
Electrical Substance out of the Air; the more the Earth must needs
be charged with it. And therefore it seems worthy of Consideration
whether any part of the Earth, being fuller of the terrible
Substance, may not be exposed to more shocking Earthquakes. In
Boston are more erected than anywhere else in New England; and
Boston seems to be more dreadfully Shaken. O! there is no getting
out of the mighty Hand of God! If we think to avoid it in the Air,
we cannot in the Earth: Yea it may grow more fatal..."
Franklin countered that there is no religious objection to roofs on
buildings to resist precipitation, so lightning, which he proved to
be simply a giant electrical spark, should be no different. As an
act of philanthropy, Franklin decided against patenting the
invention.
In the 19th century the lightning rod became a symbol of American
ingenuity and a decorative motif. Lightning rods were often
embellished with ornamental glass balls (now prized by collectors).
The ornamental appeal of these glass balls has also been
incorporated into weather vanes. The main purpose of these balls,
however, is to provide clear evidence of a lightning strike by
shattering or falling off. If after a storm a ball is discovered
missing or broken, the property owner should then check the
building, rod, and grounding wire for damage.
Balls of solid glass occasionally were used in a method purported to
prevent lightning strikes to ships. Although this failed to work, it
is worth noting because it reveals a lot about pre-scientific
thought. The basic principle was that glass objects, being
non-conductors, are seldom struck by lightning. Therefore, goes the
theory, there must be something about glass that repels lightning.
Hence the best method for preventing a lightning strike to a wooden
ship was to bury a small solid glass ball in the tip of the highest
mast. The random behavior of lightning ensured that the method
gained a good bit of credence even after the development of the
marine lightning rod soon after Franklin's initial work.
Nikola Tesla's U.S. Patent 1,266,175 was an improvement in lightning
protectors. The patent was granted due to a fault in Franklin's
original theory of operation; the pointed lightning rod actually
ionizes the air around itself, rendering the air conductive, which
in turn raises the probability of a strike. Many years after
receiving his patent, in 1919 Dr. Tesla wrote an article for The
Electrical Experimenter entitled "Famous Scientific Illusions", in
which he explains the logic of Franklin's pointed lightning rod and
discloses his improved method and apparatus.
Some DuPont Explosives manufacturing sites, which were surrounded by
pine trees, used various lightning protection devices. During the
1950s, DuPont made nitroglycerin in some buildings and moved it in
'Angel Buggies' to the packing building. Employees at those sites
were very sensitive to potential lightning strikes.
In the 1990s, the 'lightning points' were replaced as originally
constructed when the statue of Freedom atop the United States
Capitol building in Washington, D.C. was restored. The statue was
designed with multiple devices that are tipped with platinum. The
Washington Monument also was equipped with multiple lightning
points, and the Statue of Liberty in New York Harbor gets hit with
lightning which is grounded out.
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