As the story goes, during a thunderstorm in 1752 Franklin flew the most famous kite in history. Sparks jumped from a key tied to the bottom of the kite string to the knuckles of his hand. He had verified his theory. But like most things in Ben Franklin's life, this was not without controversy.
The controversy stems from whether at the time of his experiment he knew of the earlier French results. Curiously it wasn't until 1788 that Franklin himself first wrote that he had performed the kite experiment, and then only a brief sentence was devoted to the subject. Nevertheless in October 1753 Franklin described the kite experiment in detail and stated that it had succeeded in Philadelphia, but not that he himself had performed it. The classic account of Franklin's kite flight was written by Joseph Priestly in his History and Present State of Electricity published 15 years after the flight.
Either way, Franklin still was a pioneer of observational science and inventor of the lightning rod that is still used to this day to protect wooden structures from lightning.
Farand, Max. The Autobiography of Bejamin Franklin, A Restoration of a Fair Copy. 1949.
Priestley, Joseph. The History and Present State of Electricity. 3rd ed. London, England, 1775.
“Lightning rod - Wikipedia, the free encyclopedia.” 20 Oct 2009