Did Franklin fly a kite in a thunderstorm?
6 min read
Probably yes, but not the way cartoons show it. Benjamin Franklin described the kite experiment in the Pennsylvania Gazette on 19 October 1752, without saying when he did it or that he did it himself. The details (June 1752, Philadelphia, his son William, a shed for shelter) come from Joseph Priestley's history of 1767. Lightning did not strike the kite: it drew a small charge from a storm cloud. And Franklin did not discover electricity. He showed that lightning is electrical.
The claim, and the verdict
The claim: in a raging thunderstorm Benjamin Franklin flew a kite with a key on the string, lightning struck it, and he discovered electricity.
The verdict: one part true, three parts wrong. Most historians accept that Franklin flew an electrical kite in Philadelphia in the summer of 1752. But the kite was not struck by lightning, which would very likely have killed him. He did not discover electricity, which had been studied for decades and stored in Leyden jars since 1745 and 1746. And his experiment was not the first proof that lightning is electrical: a French team had already done it a month earlier, following Franklin's own instructions. His real achievement was the idea, the experiment design and the invention that followed, the lightning rod.
What the evidence shows: a dated source table
| Date | Source or event | What it shows |
|---|---|---|
| 29 July 1750 | Franklin to Peter Collinson, London | Proposes the “sentry box” experiment: a pointed iron rod on a high tower to draw electricity from storm clouds. |
| 1751 | Experiments and Observations on Electricity, London | Collinson publishes Franklin's letters. A French translation follows in 1752. |
| 10 May 1752 | Marly-la-Ville, near Paris | Thomas-François Dalibard's team carries out Franklin's rod experiment and draws sparks from a storm. The first proof that lightning is electrical. |
| June 1752 | Philadelphia (date from Priestley, 1767) | Franklin's kite experiment, before news from France reached him. |
| 19 October 1752 | Franklin's statement, Pennsylvania Gazette | Describes how to make and fly an electrical kite and says the experiment has succeeded in Philadelphia. Does not give a date or say who did it. |
| 21 December 1752 | Royal Society, London | Franklin's account is read to the Society. |
| Late 1752 | Poor Richard's Almanack for 1753 | Gives instructions for lightning rods to protect houses. |
| August 1753 | St Petersburg | Georg Wilhelm Richmann is killed while trying a similar experiment with an insulated rod. |
| November 1753 | Royal Society | Awards Franklin the Copley Medal for his electrical work. |
| 1767 | Joseph Priestley, The History and Present State of Electricity | The fullest account: June 1752, with his son William, sheltering in a shed, sparks drawn from the key. |
The awkward fact is the gap. Franklin never wrote a first person, dated account of flying the kite. His 1752 statement reads like instructions: a cross of two light sticks, a large thin silk handkerchief, a sharp pointed wire at the top, a twine string, a silk ribbon at the hand end and a key where twine and ribbon meet. The person holding it should stand inside a door or window so the silk stays dry. When rain wets the twine, the key gives sparks to a knuckle and can charge a Leyden jar. He concluded that this showed
“the Sameness of the Electric Matter with that of Lightning compleatly demonstrated.”
Priestley, who met Franklin in London in the 1760s, almost certainly got his details from Franklin himself. The editors of The Papers of Benjamin Franklin see no good reason to doubt the June 1752 date.
Was Franklin struck by lightning?
No. The kite collected electric charge from the storm cloud overhead. Priestley says Franklin noticed loose threads of the twine standing up and moving apart, as charged threads do, and then drew a spark from the key with his knuckle. That is a small, static charge, like the spark from a door handle, not a lightning strike.
A direct strike carries vastly more energy. Richmann's death in St Petersburg in August 1753, during a similar experiment, showed how dangerous the work was. Franklin was lucky, careful, or both.
How the legend grew
Nineteenth century prints and schoolbooks made the scene heroic: a wild storm, a bolt hitting the kite, Franklin often shown as an old man with a small boy. In fact William was about twenty one, and the drama was in the idea, not the weather. Popular prints copied one another, so the same mistakes spread from picture to picture.
A few writers have argued that Franklin never flew the kite at all. The journalist Tom Tucker, in Bolt of Fate (2003), suggested the October statement was a teasing hoax. Most historians are not persuaded, because Franklin described the method precisely, Priestley's details probably came from him, and Franklin had nothing to gain by inventing it after the French had already succeeded.
What Franklin actually said and did about electricity
Franklin's electrical letters, written in the late 1740s and early 1750s, introduced words we still use, including battery, charge, positive and negative. He proposed that electricity is a single fluid, and he was fascinated by how sharp points draw off charge, the principle behind the lightning rod. In 1750 he wrote to Collinson:
“There is something however in the experiments of points, sending off, or drawing on, the electrical fire, which has not been fully explained”
The lightning rod was the practical result, and it spread quickly across America and Europe. Franklin did not patent it. You can ask him about the kite, the French experiment and the rod by talking with Benjamin Franklin in Yuga, by voice or text. It is an AI recreation built from his writings and the record, not Franklin, and it can make mistakes, so cite the Papers of Benjamin Franklin in your work.
How to check a famous experiment story
- Find the scientist's own published account, and note what it does and does not say.
- Find when the details first appear, and from whom. Here, 1767, from Priestley.
- Check the physics. A lightning strike and a static spark are very different.
- Check who else was doing the same work. The French team succeeded first.
More: questions to ask Benjamin Franklin, famous inventors and their inventions, America 250 and the founders and how to check if a quote is real.
Questions people ask
- When did Benjamin Franklin fly his kite?
- In June 1752, in Philadelphia, according to Joseph Priestley's History and Present State of Electricity (1767), which probably drew on Franklin's own memory. Franklin's printed account appeared in the Pennsylvania Gazette on 19 October 1752 but gave no date. The often quoted date of 10 June 1752 is a later guess, not documented.
- Did Benjamin Franklin discover electricity?
- No. Electricity had been studied since ancient times and experimented with intensively in Europe in the 1740s, including the Leyden jar for storing charge, invented in 1745 and 1746. Franklin's contributions were a theory of a single electric fluid, terms such as positive and negative, the proof that lightning is electrical, and the lightning rod.
- Was Franklin the first to prove lightning is electricity?
- No. On 10 May 1752, at Marly-la-Ville near Paris, Thomas-François Dalibard's team followed Franklin's published plan and drew sparks from a storm with a tall iron rod. Franklin's kite experiment in Philadelphia came about a month later, before he had heard the news from France. The idea and design were his.
- Why did Franklin use a key?
- The metal key, tied where the wet hemp string met a dry silk ribbon, collected the charge that ran down the string and gave a convenient point to draw sparks from or to charge a Leyden jar. The dry silk insulated Franklin's hand. The key had no special purpose beyond being a handy piece of metal.
Sources
- Benjamin Franklin, “The Kite Experiment”, 19 October 1752, Founders Online (National Archives)
- Benjamin Franklin, Experiments and Observations on Electricity (London, 1751)
- Joseph Priestley, The History and Present State of Electricity (London, 1767)
- I. Bernard Cohen, Benjamin Franklin's Science (1990)
- Walter Isaacson, Benjamin Franklin: An American Life (2003)