Franklin coined the terms "positive" and "negative" charge, rejecting du Fay's notion of two kinds of electrical fluids. He imagined that during a lightning strike, the earth and sky form a gigantic Leyden jar and flew a kite in a thunderstorm and found that the silk thread showed signs of electrical charge. He was also able to charge a real Leyden jar using this energy, proving that the two electricities were identical. Franklin generalized this idea and built tall metal spires on top of buildings, which averted lightning-induced fires, the first mitigation of natural disaster through science.
A visual chronology of Asimov's ~1500 scientific inventions and discoveries.
