When did Benjamin Franklin fly his kite in a thunderstorm?
So I've been on a flying kick lately... and I really love storms and wind... but I know flying in a storm is not a great idea. This being said, Benjamin Franklin flew a kite in a thunderstorm right? I mean, maybe it's a thing great inventors do... or really lucky people who don't end up being electrocuted.
On the afternoon of June 10, 1752, the sky began to darken over the city of Philadelphia. Benjamin Franklin decided it was the perfect time to go fly a kite. He wanted to demonstrate the electrical nature of lightning, and to do so, he needed a thunderstorm.
He had his materials at the ready: a simple kite made with a large silk handkerchief, a hemp string, and a silk string. He also had a house key, a Leyden jar (a device that could store an electrical charge for later use), and a length of wire. His son William assisted him.
Franklin had originally planned to conduct the experiment atop a Philadelphia church spire, according to his contemporary, British scientist Joseph Priestley (who, incidentally, is credited with discovering oxygen), but he changed his plans once he realized he could achieve the same goal by using a kite.
Franklin and his son “took the opportunity of the first approaching thunder storm to take a walk into a field,” Priestley wrote in his account. “To demonstrate, in the completest manner possible, the sameness of the electric fluid with the matter of lightning, Dr. Franklin, astonishing as it must have appeared, contrived actually to bring lightning from the heavens, by means of an electrical kite, which he raised when a storm of thunder was perceived to be coming on.”
Despite a common misconception, Benjamin Franklin did not discover electricity during this experiment—or at all, for that matter. Electrical forces had been recognized for more than a thousand years, and scientists had worked extensively with static electricity. Franklin’s experiment simply demonstrated the connection between lightning and electricity.
To dispel another myth, Franklin’s kite was not struck by lightning. If it had been, he likely would have been electrocuted. The kite actually picked up the ambient electrical charge from the storm. Franklin constructed the simple silk kite and attached a wire to the top of it to act as a lightning rod. At the bottom of the kite he attached a hemp string, and then a silk string. The hemp would conduct an electrical charge quickly in the rain and the silk string would be kept dry, held by Franklin in the doorway of a shed.
The last piece of the puzzle was the metal key Franklin attached to the hemp string. With his son’s help he got the kite in the air during the storm. Then they waited. Franklin noticed loose threads of the hemp string standing every which way, erect, “just as if they had been suspended on a common conductor.” When Franklin moved his finger near the key, and as the negative charges in the metal piece were attracted to the positive charges in his hand, he felt a spark.
“Struck with this promising appearance, he immediately presented his knucle [sic] 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,” Priestley wrote.
Using the Leyden jar, Franklin collected the ambient electricity. Franklin’s own description of the event appeared in the Pennsylvania Gazette on October 19, 1752. In it he gave instructions for re-creating the experiment.
Franklin wasn’t the first to demonstrate the electrical nature of lightning. A month earlier it was successfully done by Thomas-François Dalibard in northern France. And a year after Franklin’s kite experiment, Baltic physicist Georg Wilhelm Richmann attempted a similar trial but was killed when he was struck by ball lightning (a rare weather phenomenon).
After his successful demonstration, Franklin continued his work with electricity, going on to perfect his lightning rod invention. He coined a number of terms used today, including battery, conductor and electrician. In 1753, he received the prestigious Copley Medal from the Royal Society, in recognition of his “curious experiments and observations on electricity.”