Ben Franklin made many discoveries about electricity, but he was best known for demonstrating the electrical nature of lightning. Franklin, however, did not seek knowledge just for its own sake.
He thought it should serve some useful purpose. The practical product of the great kite-and-key experiment was the lightning rod—a pointed iron rod that was raised above a rooftop. During storms, the rod would attract lightning and lead it, by wire, harmlessly into the ground.
Lightning rods went up everywhere during the 1750s, increasing Franklin’s reputation but not his bank account. Franklin profited little from any of his inventions. He sought patents for none of them and allowed anyone to copy them.
