Benjamin Franklin Conducts Kite Experiment on Electricity

Context

By the mid-eighteenth century, European natural philosophers had begun to explore connections between atmospheric phenomena and the newly studied force of electricity. Speculation by Jean-Antoine Nollet and others prompted public discussions and prize questions in France about whether lightning might share properties with laboratory electricity. Benjamin Franklin, already engaged in electrical experiments in colonial Philadelphia and corresponding with European colleagues, had by 1750 reversed his earlier doubts and proposed using pointed rods atop tall structures to draw charge from thunderclouds.

What Happened

Franklin had originally intended to conduct the test from a church spire under construction in Philadelphia. When that proved unavailable, he adapted the idea by constructing a kite fitted with a pointed metal wire at its apex. Assisted by his son William, he attached the kite to a hemp string that would conduct when wet, tied a metal house key—borrowed from carpenter Benjamin Loxley—to the string, and used a silk ribbon as an insulator at the ground end. During an approaching thunderstorm, the pair sheltered in an open shed or barn to keep the silk dry while flying the kite into the cloud.

Aftermath

Franklin observed the hemp fibers standing erect and drew sparks from the key, then charged a Leyden jar. He described the results in a letter published in the Pennsylvania Gazette on October 19, 1752, without detailing the precise circumstances. The account reached the Royal Society in London later that year. Franklin quickly recommended installing pointed lightning rods on buildings to conduct electrical charge safely to the ground.

Legacy

The experiment furnished empirical support for the identity of lightning and electricity and accelerated the adoption of lightning rods, which protected structures across Europe and North America. It enhanced Franklin’s standing among European savants and contributed to the growing prestige of American scientific inquiry. Popular accounts later mythologized the event, often depicting a direct lightning strike that never occurred; historians continue to note that Franklin’s own writings omitted the date and many specifics later supplied by Joseph Priestley in 1767.