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. A wire attached to the rod would lead the lightning harmlessly into the ground.
During the 1750s, lightning rods went up everywhere, increasing Franklin’s reputation, but not his bank account. Franklin made little money from any of his inventions. He didn’t patent them, and he let anyone copy them.
