Benjamin Franklin and the First Lightning Conductors


  • E. Philip Krider The University of Arizona


The Philadelphia experiments and observations on electricity, as led and communicated by Benjamin Franklin, were important in the history of science because some were new and novel and because their interpretations helped to stimulate the development of electricity as a science and the beginnings of modern physics. This work also led to the sentry box and kite experiments5 that proved once and for all that thunderclouds are electrified and that lightning is an electrical discharge. The latter discoveries, in turn, validated the key assumptions that lay behind Franklin’s supposition that tall, grounded rods would protect structures from lightning damage. Here, we will trace how Franklin’s ideas evolved and the design of the first protective rods, and then we will describe some key improvements that Franklin made to his design, after experience was gained through practice in the years from 1752 to 1762.