Electrical Fire
“Electrical Battery,” 1760–1769
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“Electrical Battery,” 1760–1769
 Static electricity tube, ca. 1747
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Static electricity tube, ca. 1747
Broadside, 1752
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Broadside, 1752
 Portrait of Benjamin Franklin, 1762
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Portrait of Benjamin Franklin, 1762
Electrical Apparatus, 1742–1747
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Electrical Apparatus, 1742–1747
 Lavoisier dans son laboratoire, 1888
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Lavoisier dans son laboratoire, 1888
Benjamin Franklin of Philadelphia, 1763
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Benjamin Franklin of Philadelphia, 1763
 Double-acting pneumatic air pump, 1750–1770
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Double-acting pneumatic air pump, 1750–1770
   
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Your kind present of an electric tube, with directions for using it, has put several of us on making electrical experiments, in which we have observed some particular phenomena that we look upon to be new. I was never before engaged in any study that so totally engrossed my attention and time.
—Letter from Benjamin Franklin to Peter Collinson, March 28, 1747
 
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The study of electricity was the most spectacular and fashionable branch of Enlightenment natural philosophy. Franklin was immediately hooked when the Library Company’s British agent, Peter Collinson, sent him a glass tube used to generate static electricity. Franklin taught himself to perform basic electrical “tricks” with it and was soon immersed in trying to understand how this surprising phenomenon worked.

Through his electrical investigations, Franklin developed important new theories, complete with new terms and instruments to describe and demonstrate them. As usual, his concern centered on developing useful applications for his discoveries: the result was a lightning protection system that is still in use today, notably on St. Paul’s Cathedral in London.

Franklin’s experiments were known all over Europe, initially through his personal correspondence and then through publications initiated by colleagues abroad. Later, Franklin’s international fame as a scientist would give him the status and political access to succeed as America’s premier diplomat.
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Thunder and Lightning
Franklin’s best known scientific insight was that thunderclouds are electrified and that lightning is, in fact, a large electric spark. To test this hypothesis, during a thunderstorm Franklin flew a kite with a pointed wire attached. When a cloud approached, the wire attracted electricity. The charge was conducted through the kite’s twine, and from an attached metal key Franklin drew sparks and charged a Leyden jar.

Previous studies of the “power of points” led Franklin to suggest that grounded iron rods might protect houses from lightning damage. “Would not these pointed rods,” Franklin asked, “probably draw the electrical fire silently out of a cloud before it came nigh to strike, and thereby secure us from that most sudden and terrible mischief?”
   
Experiments and Observations on Electricity, 1751
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Experiments and Observations on Electricity, 1751
   Top portion of a lightning rod, ca. 1756
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Top portion of a lightning rod, ca. 1756
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Indeed, in the construction of an instrument [lightning rod] so new, and of which we could have so little experience, it is rather lucky that we should at first be so near the truth as we seem to be, and commit so few errors.
—Letter from Benjamin Franklin to Ebenezer Kinnersley, February 20, 1762
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The Phillips Museum of Art