270 years ago Czech scientist Prokop Diviš built world's first grounded lightning conductor

Prokop Diviš

The discovery was made in the garden in Přímětice near Znojmo, where Diviš worked as a parish priest and conducted scientific experiments. The main function of the "weather machine" was to permanently balance the tension between the sky and the ground and avert the discharge itself.

The lightning conductor by Prokop Diviš | Photo: Prokop Diviš Museum in Přímětice

The base of the machine was a horizontal iron cross mounted on a forty meter post. The arms of the cross were supplemented by additional poles with 12 metal boxes containing layers of iron filings and 400 metal spikes. The entire structure was connected conductively to the ground by three chains. The erection of the device took place on 15 June 1754 with it functioning as a lightning rod. Diviš made observations of the self-assembled device during every storm and wrote the results in a large treatise "On the Nature of Atmospheric Electricity," which he dedicated to Empress Maria Theresa.

The parishioners did not believe the invention

The historic wooden house on the site of Prokop Diviš's birthplace,  Helvíkovice u Žamberka | Photo: Jiří Fremuth,  Czech Radio

The villagers in Přímětice were convinced that the machine was to blame for the extreme drought that hit central Europe in 1759. They invaded Diviš's garden and destroyed the entire structure. Diviš did not rebuild it, even when they begged him to do so in the next rainy year.

The American Benjamin Franklin erected his pole-mounted grounded lightning rod in Philadelphia six years after Diviš, based on a simpler idea of diverting lightning to a harmless place and preventing discharges.

Replicas of Diviš's lightning conductor can be seen either by the Prokop Diviš Memorial in Znojmo-Přímětice, at the site of the house where he was born in Helvíkovice, or on the roof of the Diviš Theatre in Žamberk.

Prokop Diviš monument in Znojmo-Přímětice | Photo: Zdeněk Truhlář,  Czech Radio