7/29/2019 Franklin and His Electric Kite

1/5

Franklin and his Electric KiteAn Experiment That Took the World by Storm

An Account of the Kite Experiment

Before that he had thought of another way of proving his theory, and with the help of hiselectrical kite had drawn lightning from a cloud. The episode of the kite, so firm andfixed in legend, turns out to be dim and mystifying in fact. Franklin himself never wrotethe story of the most dramatic of his experiments. All that is known about what he did onthat famous day, of no known date, comes from Joseph Priestley's account, publishedfifteen years afterwards but read in manuscript by Franklin, who must have givenPriestley the precise, familiar details.

"As every circumstance relating to so capital a discovery (the greatest, perhaps, sincethe time of Sir Isaac Newton) cannot but give pleasure to all my readers, I shallendeavour to gratify them with the communication of a few particulars which I have fromthe best authority."The Doctor, having published his method of verifying his hypothesis concerning thesameness of electricity with the matter of lightning, was waiting for the erection of aspire [on Christ Church] in Philadelphia to carry his views into execution; not imaginingthat a pointed rod of a moderate height could answer the purpose; when it occurred tohim that by means of a common kite he could have better access to the regions ofthunder than by any spire whatever. Preparing, therefore, a large silk handkerchief andtwo cross-sticks of a proper length on which to extend it, he took the opportunity of thefirst approaching thunderstorm to take a walk in the fields, in which there was a shedconvenient for his purpose. But, dreading the ridicule which too commonly attendsunsuccessful attempts in science, he communicated his intended experiment to nobodybut his son" -- then twenty-one, not a child as in the traditional illustrations of the scene-- "who assisted him in raising the kite.

"The kite being raised, a considerable time elapsed before there was any appearance ofits being electrified. One very promising cloud had passed over it without any effect;when, at length, just as he was beginning to despair of his contrivance, he observedsome loose threads of the hempen string to stand erect, and to avoid one another, justas if they had been suspended on a common conductor. Struck with this promisingappearance, 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. Others succeeded, even before the stringwas wet, so as to put the matter past all dispute, and when the rain had wet the stringhe collected electric fire very copiously. This happened in June 1752, a month after theelectricians in France had verified the same theory, but before he heard of anything theyhad done."

7/29/2019 Franklin and His Electric Kite

2/5

From Carl Van Doren's "Benjamin Franklin"

1938 by Carl Van Doren

How Franklin Made His Kite

Written by Benjamin Franklin to Peter Collinson, October 19, 1752

Make a small cross of two light strips of cedar, the arms so long as to reach to the fourcorners of a large thin silk handkerchief when extended; tie the corners of thehandkerchief to the extremities of the cross, so you have the body of a kite; which beingproperly accommodated with a tail, loop, and string, will rise in the air, like those madeof paper; but this being of silk is fitter to bear the wet and wind of a thunder gust without

tearing. To the top of the upright stick of the cross is to be fixed a very sharp pointedwire, rising a foot or more above the wood. To the end of the twine, next the key may befastened. This kite is to be raised when a thunder-gust appears to be coming on, andthe person who holds the string must stand within a door or window, or under somecover, so that the silk ribbon may not be wet; and care must be taken that the twinedoes not touch the frame of the door or window. As soon as any of the thunder cloudscome 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 outevery way, and be attracted by an approaching finger. And when the rain has wetted thekite and twine, so that it can conduct the electric fire freely, you will find it stream outplentifully from the key on the approach of your knuckle. At this key the phial may be

charged: and from electric fire thus obtained, spirits may be kindled, and all the otherelectric experiments be performed, which are usually done by the help of a rubbed glassglobe or tube, and thereby the sameness of the electric matter with that of lightningcompletely demonstrated.

For Whom the Bells Toll

7/29/2019 Franklin and His Electric Kite

3/5

In the early 1750s, Franklin erected a lightning rod on top of his house for the purposesof experimentation, protection and, perhaps, to get electricity for experimentationwithout having to go through the laborious process of creating it himself via a primitivebattery.Franklin's "iron rod" drew lightning down into his house. The rod was connected to a bell

and a second bell was connected to a grounded wire. Every time there was an electricalstorm, the bells would ring and sparks would illuminate his house.Franklin described the experiment as follows. The rod was:

"fixed to the top of my chimney and extending abut nine feet above it. From the foot ofthis rod a wire (the thickness of a goose-quill) came through a covered glass tube in theroof and down through the well of the staircase; the lower end connected with the ironspear of a pump. On the staircase opposite to my chamber door the wire was divided;the ends separated about six inches, a little bell on each end; and between the bells alittle brass ball, suspended by a silk thread, to play between and strike the bells whenclouds passed with electricity in them. After having frequently drawn sparks and

charged bottles from the bell of the upper wire, I was one night awakened by aloudcracks on the staircase. Starting up and opening the door, I perceived that the brassball, instead of vibrating as usual between the bells was repelled and kept at a distancefrom both; while the fire passed, sometimes in very large, quick cracks from bell to bell,and sometimes in a continued, dense, white stream, seemingly as large as my finger,whereby the whole staircase was inlightened with sunshine, so that one might see topick up a pin."Legend has it that Franklin's wife, Deborah, was so flustered by the ringing bells andflashing lights, that she wrote to her husband who was off in London, asking him how todisconnect the experiment.

Assault on BatteriesBefore Franklin started his scientific experimentation, it was thought that electricityconsisted of two opposing forces. Franklin showed that electricity consisted of a"common element" which he named "electric fire." Further, electricity was "fluid" like aliquid. It passed from one body to another -- however it was never destroyed. In a letterto Peter Collinson, Franklin wrote that the:

"fire only circulates. Hence have arisen some new items among us. We say B(and other Bodies alike circumstanced) are electricised positively; A negatively;Or rather B is electricised plus and A minus ... These terms we may use tillphilosophers give us better."

Franklin's work became the basis for the single fluid theory. When something is beingcharged, such as a car battery, electricity flows from a positive body, that with anexcess charge, to a negative body, that with negative charge. Indeed, a car battery hasplus and minus signs on its terminals.Franklin wrote Collinson in another letter that: "I feel a Want of Terms here and doubtmuch whether I shall be able to make this intelligible." Not only did Franklin have toposit theories, he also had to create a new language to fit them. Some of the electricalterms which Franklin coined during his experiments include:

7/29/2019 Franklin and His Electric Kite

4/5

battery

charge

condensor

conductor

plus

minus

positively

negatively

armature

They are still the terms we use today.

7/29/2019 Franklin and His Electric Kite

5/5