June 15 is Fly a Kite Day, on the anniversary of Benjamin Franklin’s famous kite-flying experiment. Hear the rest of the story & how to celebrate with or without a kite.
On June 15th, 1752, Benjamin Franklin flew a kite into a thunderstorm to prove his theory that lightning was an electrical discharge.
He wrote about his experiment to his friend Peter Collinson (a member of the Royal Society of London) in England, on the 9th of May, 1753. (Read the letter at Founders Online.)
Franklin began his experiments with electricity in 1747. He noticed that electricity had the same color, crooked direction, and sound as lightning.
He wanted to prove his hypothesis that lightning was a form of electricity by seeing if it passed through metal.
His plan was to get iron rods into storm clouds to conduct electricity.
He needed to be at a high elevation in order to do his experiments, but there were no hills in Philadelphia.
Benjamin Franklin’s plans to get higher.
Franklin told his friend British scientist Joseph Priestley (who discovered oxygen) that he planned on using the steeple of Christ Church for his experiment but at the time it was still in the building stage. (Priestly wrote about it in his 1767 book “History and Present Status of Electricity“)
Franklin then came up with the idea to fly a kite into the clouds during a storm. Priestly says Franklin and his son William “took the opportunity of the first approaching thunder storm to take a walk into a field 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.”
The famous kite and key experiment.
Franklin built a simple kite from a red silk handkerchief and cedarwood crosspieces. He attached a foot of wire at the top to act as a lightning rod. He attached a hemp string to the bottom of the kite.
He attached a silk string to the hemp string which he held. The hemp string would be wet from the storm and conduct the electricity, but the silk string would be dry from him standing in the shed.
They attached an iron house key to the hemp string to act as a conductor.
Priestly wrote that just as they were beginning to despair, Franklin noticed that the fibers on the hemp string were standing erect “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.”
The key was connected to a Leyden jar where Priestly says they “collected electric fire very copiously,” and it was released later.
Franklin describes his Fly a Kite Day.
In the October 19, 1752 Pennsylvania Gazette Benjamin Franklin described how to do the experiment, and then concluded his article with this statement.
“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 wet 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 charg’d; and from Electric Fire thus obtain’d, Spirits may be kindled, and all the other Electric Experiments be perform’d, 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 compleatly [sic] demonstrated.”
No, Benjamin Franklin did not discover electricity.
We sometimes hear that Benjamin Franklin “discovered” electricity. This is not accurate. He came to understand the positive and negative discharges (the shock on his knuckle from positive charges in his body), and the connection between lightning and electricity.
Electricity was already discovered and regarded as the Interaction Between Two Fluids. Franklin was the first to call them “plus” and “minus”.
In fact, Benjamin Franklin wasn’t even the first person to do his own experiment. He had shared his idea about conducting lightning with iron rods with Peter Collinson, a member of the Royal Society of London, who didn’t understand it’s importance.
The French were first to do Franklin’s experiment.
In a pamphlet “Opinions and Conjectures,” July 29, 1750, Franklin suggested that there was an experiment that could prove the electrical nature of lightning.
Georges-Louis Leclerc, Comte de Buffon, a count and scientist in his own right, suggested that physicist Thomas-François Dalibard translate the pamphlet and try the experiment. He translated it in Paris in February 1752.
He erected a rod of iron 40 feet high. On May 10, 1752, a storm went over. People moved closer and saw sparks of fire, just like in electrical experiments.
In Dalibard’s report to the Royal Academy of Sciences on May 13th, 1752, (a month before Benjamin Franklin flew his kite.) Dalibard referred to it as the “Philadelphia experiment” and confirmed that Franklin was correct – clouds are electrically charged.
Not everyone was successful with the “Philadelphia Experiment”.
Unfortunately, not everyone who tried the experiment survived. In Russia, Swedish Physicist Georg Wilhelm Richmann tried the experiment with a jar of water with brass fittings. An iron bar stuck out of the jar and was attached to a wire on the roof of the building.
Richmann was standing a foot from the jar when a ball of lightning came down the bar and struck him on the forehead. There was an explosion that knocked both Richmann and his engraver backwards and the door off its hinges.
A letter from Moscow giving the account of Richmann’s death, dated August 23, 1753, was reprinted in the The Pennsylvania Gazette, March 5, 1754.
It is believed that the last paragraph was written by Benjamin Franklin as an explanation of the accident.
“The new Doctrine of Lightning is, however, confirm’d by this unhappy Accident; and many Lives may hereafter be sav’d by the Practice it teaches. M. Richmann being about to make Experiments on the Matter of Lightning, had supported his Rod and Wires by Electrics per se, which cut off their Communication with the Earth; and himself standing too near where the Wire terminated, help’d with his Body to compleat that Communication. It is plain the Wire conducted the Lightning to him thro’ the whole Length of the Gallery: And had his Apparatus been intended for the Security of his House, and the Wire (as in that Case it ought to be) continued without Interruption from the Roof to the Earth, it seems more than probable that the Lightning would have follow’d the Wire, and that neither the House nor any of the Family would have been hurt by that unfortunate Stroke.”
No, Franklin’s kite was not struck by lightning.
You see, Benjamin Franklin was very fortunate that his kite was not struck by lightning or he could have been electrocuted, too. The negative charges in the air were attracted to the kite, went through the string, key, and into the Leyden jar. Franklin didn’t know that he needed to ground his “apparatus” so his body wouldn’t “complete the communication” of the lightning to the ground yet. He learned about grounding from a turkey, the bird that he wanted as the American national bird.
The American Physical Society tells the story well: “To be sure, Franklin had a great sense of humor and clearly enjoyed the parlor tricks, and he liked having an audience for his electrical amusements. For instance, in the early summer of 1749, somewhat disappointed at not yet having produced anything of great use to mankind with electricity, Franklin hosted an elaborate electrical barbecue. He killed a turkey by electrical shock, then roasted it using the electrical jack, an electric device he invented that would rotate the turkey as it roasted before a fire, which was kindled by an electrified bottle. Guests drank from electrified glasses that gave them a small shock as they sipped their wine, and were entertained as sparks were sent across the river. Franklin also devised a game called “treason,” which involved an electrified portrait of the king, with a removable gilt crown. The picture was rigged so that anyone who tried to remove the crown while holding the gilt edge of the picture would be shocked.”
Franklin thought electricity made the turkey tender, so he continued to cook his turkey this way until in 1750 he shocked himself while electrocuting his holiday turkey. In his Christmas letter Franklin describes the event. “I have lately made an experiment in electricity that I desire never to repeat. Two nights ago, being about to kill a turkey by the shock from two large glass jars, containing as much electrical fire as forty common phials, I inadvertently took the whole through my own arms and body, by receiving the fire from the united top wires with one hand, while the other held a chain connected with the outsides of both jars.”
Franklin learns how to ground his holiday turkey & buildings.
From this he learned about grounding. His purpose in experimenting with lightning was to try and stop house fires in storms. He now knew what he needed to be successful. He could use an iron rod on the top of a building as a Lightning Rod. The electricity from a bolt of lightning could be safely carried from the top of the building through a wire attached to another iron bar in the ground.
In his 1753 Poor Richard’s Almanack, Franklin wrote about his lightning rod, “It has pleased God in his goodness to mankind, at length to discover to them the means of securing their habitations and other buildings from mischief by thunder and lightning. The method is this: Provide a small iron rod (it may be made of the rod-iron used by the nailers) but of such a length, that one end being three or four feet in the moist ground, the other may be six or eight feet above the highest part of the building. To the upper end of the rod fasten about a foot of brass wire, the size of a common knitting-needle, sharpened to a fine point; the rod may be secured to the house by a few small staples. If the house or barn be long, there may be a rod and point at each end, and a middling wire along the ridge from one to the other. A house thus furnished will not be damaged by lightning, it being attracted by the points, and passing thro the metal into the ground without hurting any thing. Vessels also, having a sharp point rod fix’d on the top of their masts, with a wire from the foot of the rod reaching down, round one of the shrouds, to the water, will not be hurt by lightning.”
Finally everyone acknowledged Benjamin Franklin’s success because now they understood the importance of understanding the connection between electricity and lightning.
The Franklin Institute: Benjamin Franklin and the Kite Experiment
The loc.gov Wise Guy: Go Fly a Kite
What now? Well, you could fly a kite. Or, watch a movie with kite flying. Or both.
See a list of movies about kites in our Movie Bucket List. There’s a kite flying in a romance, a drama, a kids movie, a teen movie, a family movie and a peaceful kite moment in a horror movie. Also a kite snack to munch on while watching.
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