Benjamin Franklin's lightning experiment. Coloured artwork of Benjamin Franklin (1706-1790) and his 21- year-old son William, performing their famous lightning experiment of 1752. They flew a kite in a thunderstorm. A metal wire on the kite attracted a lightning strike and electricity flowed down the string to a key, charging a Leyden jar (capacitor) seen near Franklin's hand. This experiment proved that lightning was an electrical phenomenon, and supported Franklin's invention of lightning rods. Some scientists died repeating the experiment, and the Franklins were lucky they were not killed themselves. The original artwork was based on the description Franklin gave to Joseph Priestley.