Most everyone knows that Benjamin Franklin was not only a famous statesman but also a great inventor and scientist, particularly in the field of electricity. He actually introduced much of the electrical terminology still in use today, including battery, conductor, positive charge, negative charge, current and discharge.
Among his many electrical experiments, the one for which Franklin is most celebrated is his successful attempt to capture the electricity of thunderclouds in a jar. But this victory might never have happened if not for a painful lesson he’d learned from one of his lesser-known tests, an experiment performed two years earlier, in December 1750. During that failed endeavor, Franklin was traumatized and humbled by an unexpected foe: a turkey.
Franklin’s strategy for the June 1752 experiment—inspired, perhaps, by that avian accident—was to fly a kite with a wire pointing up from its top near a passing thundercloud. He reasoned that static electricity in the cloud would be attracted to the wire and flow down the wet kite string on its way to the ground. But he was concerned that if he were to hold the end of the kite string directly, he might very well be killed as the electricity passed through him. So, he decided to take precautions by tying the end of the kite string to a metal key and connecting the key to a silk ribbon. He would control the kite by holding the silk ribbon rather than the string.
Because dry silk is an excellent electrical insulator, Franklin felt it would provide him the needed protection against the electricity. To ensure the silk ribbon remained dry, he flew the kite while standing in a small rain shelter. Sure enough, when the kite was in the sky, static electricity moved down the wet string as far as the key—but not through the silk ribbon to his body. Franklin then touched the metal key to an electrode protruding from the top of a Leyden jar (an electricity-storing glass jar recently invented by Dutch physicist Pieter van Musschenbroek). He’d captured the thundercloud’s electricity in a glass jar, making history in the process. And, just as importantly, he’d live to tell about it.
Given the magnitude of electricity that Franklin was handling, his precautions may seem insufficient to modern observers; nevertheless, he did consider the dangers and had planned accordingly to protect his life. Precisely because he survived, his kite experiment is now world famous.