American printer, writer, politician, diplomat, and scientist. He invented bifocals and the Franklin stove. He also experimented with Leyden Jars. In 1752, he flew a kite attached to a silk string in a thunderstorm, and showed that a metal key tied to the thread would charge a Leyden jar. (Incidentally, the next two people who attempted the experiment were killed in the effort.) His experiments with Leyden jars showed that they discharged more easily if near a pointed surface. He thus suggested the use of lightning rods. He named the two kinds of electricity positive and negative, unfortunately assigning negative charge to what later was found to correspond to material with an excess of electrons.