This rod is a life-saver

In mythologies associated with almost every ancient civilisation, thunder and lightning were considered weapons of the gods, sent down to signal divine displeasure at worldly goings-on. In medieval Europe, these beliefs were reinforced by instances of lightning strikes on churches – which, as the tallest structures in the landscape, were paradoxically more vulnerable. In order to 'appease the gods', the clergy organised for prayers and bell-ringing during storms, but since the church walls channelled the 'thunderbolts', this had lethal consequences for the ringers.

From early in the 18th century, however, men of science sought a more rational explanation for these meteorological pyrotechnics. This led them to the study of electricity, in particular the similarity between short electric sparks and the lightning discharge, and the manner in which, as some of them believed, sharp points of metal could remove or discharge electricity from electrified bodies. The most consequential of these experiments were those that Benjamin Franklin, at that time a publisher and a dabbler in philosophical pursuits, conducted on electrical apparatuses from the 1740s.

In 1750, in a letter to The Royal Society, Franklin outlined the idea for an arrangement that gave a theoretical basis for the lightning conductor. He wondered if houses and churches could be saved from lightning strikes by fixing "on the highest parts of these edifices... upright rods of iron made as sharp as a needle... and (by fixing) from the foot of these rods a wire down the outside of the building into the ground..." Would not these rods "draw the electric fire silently out of a cloud before it came nigh enough to strike, and thereby secure us...?" he theorised.

However, establishing the precise details of Franklin's experiment becomes difficult. According to contemporaneous accounts, he conducted his famed "kite experiment" – in which a kite with a pointed, conductive wire attached to its apex was flown near thunder clouds to "collect" electricity from the air and conduct it down the wet kite string to the ground – in June 1752. However, in his description of the experiment in The Pennsylvania Gazette, which appeared in October that year, he made no mention that he himself had performed the experiment.

This has led sceptics to question Franklin's claim to having conducted the experiment himself. Science historian Tom Tucker claims that the kite experiment was Franklin's "scientific hoax".

However, other science historians, including I. Bernard Cohen (bit.ly/defending-franklin), have vigorously defended the veracity of the kite experiment. In Franklin's own time, the experiment established him as a Renaissance Man. The image of Franklin holding aloft a kite, beneath an ominous thundercloud, became an iconic one. As Tucker notes, it is the only image of a scientific experiment ever printed on U.S. currency. Yet, given heightened religious orthodoxy, resistance to erecting lightning rods in churches persisted in some countries even a century later (bit.ly/rod-resist). Even so, in the 270-plus years since the lightning rod was invented, it has saved countless lives and property.

In addition to inventing the lightning rod, Franklin went on to contribute in countless other fields – in the world of science and beyond. Indicatively, he influenced the science of demography and population studies, and contributed to oceanography and political theory. In addition, he advanced the American independence movement, and was one of the signatories to the Declaration of Independence. His was a truly da Vincian mind; and, like the best lightning conductors are, it was also well grounded.