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Thunder and Lightning:
Franklin's best known scientific insight was that thunderclouds are electrified and that lightning is, in fact, a large electric spark. To test this hypothesis, during a thunderstorm Franklin flew a kite with a pointed wire attached. When a cloud approached, the wire attracted electricity. The charge was conducted through the kite's twine, and from an attached metal key Franklin drew sparks and charged a Leyden jar.
Previous studies of the "power of points" led Franklin to suggest that grounded iron rods might protect houses from lightning damage. "Would not these pointed rods," Franklin asked, "probably draw the Electrical Fire silently out of a Cloud before it came nigh to strike, and thereby secure us from that most sudden and terrible Mischief?" |