OTD Ben Franklin Kite Experiment

June 10, 1752

Benjamin Franklin flies a kite during a thunderstorm.

How the founding father's experiment impacted modern science (and ignited myths along the way).

“…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.”

Friend of Franklin and discoverer of oxygen, Joseph Priestly, in a 1767 account on the groundbreaking discovery using metal as a conductor for electrical charges – or, as he described it: “To demonstrate, in the completest manner possible, the sameness of the electric fluid with the matter of lightning…”

A Long Time Coming

Franklin had been researching electricity & various hypotheses for years.
His original experiment was designed to occur on top of a church’s steeple; he planned to attach iron rods to the top of the steeple to test for electrical charges.
However, the church’s construction was taking too long. As a result, it occurred to him to build a kite suitable for testing electrical charges during a thunderstorm.

The Spark

Materials: A kite made out of a silk handkerchief, hemp string, silk string, sharp wire, a Leyden jar (stores electrical charge for later use), & a metal house key.
Procedure: When the storm began, Franklin conducted the experiment from the ground using his newly-developed kite. With the help of his son, he flew the kite & discovered a spark when the kite drew electric charges.
Franklin’s theory was solidified when the key, attached to the bottom of the kite, received a negative charge & shocked him.

Truth vs. Myth

Franklin was not the first person to discover electricity. Scientists had already been working extensively with (static) electricity up to the point of the experiment.
His kite was not struck by lightning; rather, it collected the nearby electrical charge from the lightning.
Franklin’s experiment was not the first to demonstrate the electrical nature of lightning. It was first tested a month beforehand in France, but Franklin had not heard of the findings until after his own experiment.

Why it matters: This well-known experiment laid the groundwork for the lightning rod and helped develop a better understanding of positive and negative charges. It’s just one of many inventions developed or inspired by Benjamin Franklin.