- For generations of science students, the ultimate don't-try-this-at-home
experiment has been the wild account of Benjamin Franklin flying a kite
in a thunderstorm to snare electricity from the clouds.
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- This month marks the 250th anniversary of that daring
investigation. The Bakken Library and Museum in Minneapolis recently opened
an exhibit commemorating it and Franklin's contributions to electrical
knowledge.
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- Did the kite experiment really happen, though?
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- There is no doubt that Franklin profoundly advanced the
knowledge of electricity.
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- You can thank him the next time batteries power your
flashlight on a dark and stormy night. He laid the groundwork for the invention
of batteries and many other practical uses of electricity.
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- But debate and mystery surround the kite story.
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- For Franklin and his contemporaries, the mystery was
electricity itself. It seems almost impossible today -- when electricity
defines our urban skylines, keeps home appliances humming and even prods
hearts to beat on pace -- to imagine a time it wasn't part of everyday
life.
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- In Franklin's time, though, it was a rather spooky but
fascinating novelty.
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- "It was a very hot topic, not only among scientists,
but the general public as well," said David Rhees, the Bakken's executive
director and an expert on the history of electricity.
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- Indeed, Franklin and other dabblers in the field amused
their friends with electrical games and gags.
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- In 1749, Franklin wrote this bizarre plan for a party:
A turkey would be killed by electrocution and then roasted over a fire
started with a spark from a Leyden jar (a simple container for static electricity).
The drinks would be rigged to give guests a mild shock on the first sip.
And after dinner, the guests would play games involving passing shocks
to one another.
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- A party room at the Bakken provides electrostatic toys
that reenact the games.
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- Serious contributions
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- Scientists honor Franklin. though, for more serious contributions
to the understanding of electricity. His advancement of electrical theory
laid groundwork for modern physics, said E. Philip Krider, a professor
at the Institute of Atmospheric Physics at the University of Arizona in
Tucson.
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- The prevailing theory had been that electricity was made
of two invisible fluids. Franklin asserted that it was a common element
that passed in fluid-like fashion from one body to another. He named an
excess of electricity a "positive" and a deficiency of it a "negative."
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- Franklin's "single fluid theory" doesn't describe
everything we know about electricity today, but it set the course for modern
thinking.
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- Perhaps more mind-boggling to ordinary people in 1752
was Franklin's conclusions that thunderclouds are electrified and that
he could tap them for what he called "electric fire."
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- The kite experiment would provide the proof, and it was
profound not only from a scientific point of view but also in terms of
the public's perception of electricity, Krider said.
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- Test mystery
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- The modern-day mystery begins with Franklin's failure
to directly report the study. The only witness seems to have been his 21-year-old
son William. Because the exact date is unclear, groups celebrating the
250th anniversary are guessing when to stage their observances. The Franklin
Institute in Philadelphia plans to re-enact the experiment today.
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- Franklin sent a friend instructions for making a similar
kite in 1752. But it took 15 years before a detailed report was published
-- not by Franklin, but by Joseph Priestley, an English chemist who apparently
had corresponded with Franklin about the research.
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- Rhees and other scholars speculate that Franklin may
have been embarrassed about playing with a kite, which would have been
seen as undignified for him.
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- It's also likely, Krider said, that Franklin didn't bother
to report it because the outcome seemed so obvious to him.
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- The upshot is that other scientists conducted similar
experiments long before Franklin's was reported. A French group reported
its version of the study in May 1752, beating Franklin by a month. Thus,
Franklin surely wasn't the first to perform the landmark experiment, and
some scientists question whether he did it at all.
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- The point to remember, Rhees said, is that the other
groups readily acknowledged that their ideas came from a book Franklin
had published in 1751, Experiments and Observations on Electricity.
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- "All in all, you have to acknowledge that he was
the genius who triggered this series of experiments that had enormous impact,"
Rhees said.
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- Priestley wrote that Franklin had been waiting for workers
to erect a spire on Christ Church in Philadelphia, which would provide
a tall point to test his theory. Then, "it occurred to him that by
means of a common kite he could have better access to the regions of thunder
than by any spire," Priestley wrote.
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- The kite featured a pointed wire intended to draw electricity
from a cloud and zap it down wet twine to a metal key.
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- At first, Franklin was disappointed. Priestley wrote:
"One very promising cloud had passed over it without any effect."
Just as Franklin began to despair, he saw strands of the twine twitch.
"Struck with this promising appearance, he immediately presented his
knuckle to the key, and [let the reader judge of the exquisite pleasure
he must have felt at that moment] the discovery was complete," Priestly
wrote. "He perceived a very evident electric spark."
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- Despite skepticism in some circles, Rhees accepts Priestley's
account: "He had it directly from Franklin. I think it's clear that
Franklin did fly his kite."
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- Genius aside, Franklin took a chance that many people
would consider foolish. He was lucky in that the kite didn't take a direct
lightning strike.
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- Lest modern-day scientists forget that lightning is not
a toy, the Bakken exhibit also includes stunning photographs of deadly
bolts striking Minneapolis during a 1998 storm.
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- Sharon Schmickle is at sschmickle@startribune.com .
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- © Copyright 2002 Star Tribune. All rights reserved.
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