Father Secchi and the first Italian magnetic observatory

Abstract. The first permanent magnetic observatory in Italy was built in 1858 by Pietro Angelo Secchi, a Jesuit priest who made significant contributions in a wide variety of scientific fields, ranging from astronomy to astrophysics and meteorology. In this paper we consider his studies in geomagnetism, which have never been adequately addressed in the literature. We mainly focus on the creation of the magnetic observatory on the roof of the church of Sant'Ignazio, adjacent to the pontifical university, known as the Collegio Romano. From 1859 onwards, systematic monitoring of the geomagnetic field was conducted in the Collegio Romano Observatory, for long the only one of its kind in Italy. We also look at the magnetic instruments installed in the observatory, which were the most advanced for the time, as well as scientific studies conducted there in its early years.