Make a small Cross of two light Strips of Cedar, the Arms so long as to reach to the four Corners of a large thin Silk Handkerchief when extended; tie the Corners of the Handkerchief to the Extremities of the Cross, so you have the Body of a Kite; which being properly accommodated with a Tail, Loop and String, will rise in the Air, like those made of 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 pointed Wire, rising a Foot or more above the Wood. To the End of the Twine, next the Hand, is to be tied a silk Ribbon, and where the Twine and the silk join, a Key may be fastened.
This is Benjamin Franklin's description of how to construct a kite that could be used to extract electricity from clouds. It comes from a letter written to Peter Collinson, with whom he corresponded on matters of electricity and other subjects. It was theorized that lightning was an electrical discharge. Franklin and others had studied electricity using Leyden jars - early storage devices that were used like batteries, although technically they are capacitors. Electricity was normally generated using electrostatic generators, which rubbed cloths against solid objects. This created static electricity in much the same way that walking on a carpet can. Franklin was able to confirm that clouds carry an electrical charge that could be stored and handled exactly as if it was the electricity extracted through their usual methods.
Joseph Priestley, another friend of Franklin, set the actual date of the experiment as June 30, 1752. Franklin is said to have flown a kite from the steeple of Christ Church in Philadelphia, with the assistance of his 21-year-old son. The description indicates that a few small clouds could be used to pull a significant amount of electricity from the sky.
This Kite is to be raised when a Thunder Gust appears to be coming on, and the Person who holds the String must stand within a Door, or Window, or under some Cover, so that the Silk Ribbon may not be wet; and Care must be taken that the Twine does not touch the Frame of the Door or Window. 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 demonstrated.
It has since been determined that Franklin was not the first to do an experiment such as this. There are, indeed, those who doubt he ever did it at all, that he may have only proposed what was necessary for this experimental proof. Still, this was one of the ways he made his name as a meticulous and noteworthy scientist and philosopher. Drawing lighting out of the clouds and into bottles made him famous enough, two decades later, to be a great help to the cause of the American Revolution.
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