June 10, 1752: Benjamin Franklin, inventor of bifocal glasses, the Franklin stove, one of those that wrote the Declaration of Independence and the Constitution, ambassador, Governor of Pennsylvania, on June 10 1752 in Philadelphia, flew a kite during a thunderstorm and collected an ambient electrical charge in a Leyden jar, enabling him to demonstrate the connection between lightning and electricity. According to the Franklin Institute, Franklin had been waiting for an opportunity like this. He wanted to demonstrate the electrical nature of lightning, and to do so, he needed a thunderstorm. He had his materials at the ready: a simple kite made with a large silk handkerchief, a hemp string, and a silk string. He also had a house key, a Leyden jar (a device that could store an electrical charge for later use), and a sharp length of wire. His son William assisted him. Franklin had originally planned to conduct the experiment atop a Philadelphia church spire, according to his contemporary, British scientist Joseph Priestley (who, incidentally, is credited with discovering oxygen), but he changed his plans when he realized he could achieve the same goal by using a kite. Franklin and his son “took the opportunity of the first approaching thunder storm to take a walk into a field,” Priestley wrote in his account. “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.” Despite a common misconception, Benjamin Franklin did not discover electricity during this experiment—or at all, for that matter. Electrical forces had been recognized for more than a thousand years, and scientists had worked extensively with static electricity. Franklin’s experiment demonstrated the connection between lightning and electricity. To dispel another myth, Franklin’s kite was not struck by lightning. If it had been, he probably would have been electrocuted. Franklin became interested in electricity in the mid-1740s, a time when much was still unknown on the topic, and spent almost a decade conducting electrical experiments. He coined a number of terms used today, including battery, conductor and electrician. He also invented the lightning rod, used to protect buildings and ships. By the time he died in 1790 he was arguably the most famous man in the world.
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