On this day in 1752, Ben Franklin's kite-flying experiment proved lightning and electricity were related while flying a kite with a key attached. In Sept. 1752, he equipped his house with a lightning rod, connecting it to bells that ring when rod is electrified. He explained how to perform a kite experiment in the 19 Oct 1752 issue of the Pennsylvania Gazette.
In July 1750 he devised an experiment involving a sentry-box with a pointed rod on its roof, to be erected on hilltop or in church steeple, with rod attached to a Leyden jar which would collect the electrical charge,
and thus prove lightning to be a form of electricity. Link