Franklin's Lightning Experiment, June 10, 1752
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Franklin's Lightning Experiment, June 10, 1752

An account of Benjamin Franklin's experiment with a kite to observe the relationship between lightning and electricity.

On June 10th 1752, Benjamin Franklin flies a kite during a thunderstorm and collects a charge in a Leyden jar when the kite is struck by lightning, enabling him to demonstrate the electrical nature of lightning. Franklin became interested in electricity in the mid-1740s, a time when much was still unknown on the topic, and spent almost a decade conducting electrical experiments. He coined a number of terms used today, including battery, conductor and electrician. He also invented the lightning rod, used to protect buildings and ships.

The Experiment

While this experiment is one of the most famous in the history of science, the circumstances and date of the experiment come from Joseph Priestley as Franklin never wrote the account of his lightning experiment. Joseph Priestley's account, published fifteen years afterwards was read in manuscript by Franklin, who most likely gave Priestley the details. Joseph Priestley was an 18th-century English theologian.

“The kite being raised, a considerable time elapsed before there was any appearance of its being electrified. One very promising cloud had passed over it without any effect; when, at length, just as he was beginning to despair of his contrivance, he observed some loose threads of the hempen string to stand erect, and to avoid one another, just as if they had been suspended on a common conductor. 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. He perceived a very evident electric spark. Others succeeded, even before the string was wet, so as to put the matter past all dispute, and when the rain had wet the string he collected electric fire very copiously. This happened in June 1752, a month after the electricians in France had verified the same theory, but before he heard of anything they had done." (Source: Priestley’s account)

In a need to describe his experiments, Franklin had to come up with new definition or words to describe the various components and effects. Many are still used today;

• battery

• charge

• condenser

• conductor

• plus

• minus

• positively

• negatively

• armature

Benjamin Franklin Drawing Electricity from the Sky" by Benjamin West (1738-1820).

The Kite

Make a small cross of two light strips of cedar, the arms so long as to reach to the four corners of a large thin silk handkerchief when extended; tie the corners of the handkerchief to the extremities of the cross, so you have the body of a kite; which being properly accommodated with a tail, loop, and string, will rise in the air, like those made of paper; but this being of silk is fitter to bear the wet and wind of a thunder gust without tearing. To the top of the upright stick of the cross is to be fixed a very sharp pointed wire, rising a foot or more above the wood. To the end of the twine, next the key may be fastened. This kite is to be raised when a thunder-gust appears to be coming on, and the person who holds the string must stand within a door or window, or under some cover, so that the silk ribbon may not be wet; and care must be taken that the twine does not touch the frame of the door or window. As soon as any of the thunder clouds come over the kite, the pointed wire will draw the electric fire from them, and the kite, with all the twine, will be electrified, and the loose filaments of the twine, will stand out every way, and be attracted by an approaching finger. And when the rain has wetted the kite and twine, so that it can conduct the electric fire freely, you will find it stream out plentifully from the key on the approach of your knuckle. At this key the phial may be charged: and from electric fire thus obtained, spirits may be kindled, and all the other electric experiments be performed, which are usually done by the help of a rubbed glass globe or tube, and thereby the sameness of the electric matter with that of lightning completely demonstrated. (Source: Letter from Benjamin Franklin to Peter Collinson, October 19, 1752)

Franklin’s Lightning Bells

In the early 1750s, Franklin erected a lightning rod on top of his house for the purposes of experimentation, protection and possibly to get electricity for experimentation without having to go through the arduous process of constructing a primitive battery.

Franklin's "iron rod" drew lightning down into his house. The rod was connected to a bell and a second bell was connected to a grounded wire. Every time there was an electrical storm, the bells would ring and sparks would light up his house.

Read more about Benjamin Franklin at http://colonialhall.com/franklin/franklin.php

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Comments (6)
Ranked #63 in Science

Great job.

Very interesting Jerry! I did not know a lot of what you have unearthed.

I loved this! and you are so clever getting it published on the same date...well a few hundred years out but 10/06, I guess you knew this already!

Ranked #63 in Science

Misplaced praise, Colin. Daniel Snyder penned this article, not I,

Ranked #38 in Science

Writing the article was the easy part, ol' Ben did all the hard work!

Ranked #12 in Science

He was an extraordinary man

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