Epistola Petri Peregrini de Maricourt ad Sygerum de Foucaucourt, militem, de magnete

The Epistola Petri Peregrini de Maricourt ad Sygerum de Foucaucourt, militem, de magnete, commonly known as Epistola de magnete, is a 13th-century treatise by Peter Peregrinus of Maricourt. This work is significant as the first extant document to describe the properties of magnets.12

In the Epistola, Peregrinus details his experiments and observations on magnetism. He was the first to use the term "pole" in relation to magnets and described how to identify the north and south poles of a magnet. He also noted that like poles repel each other, while unlike poles attract. The treatise further discusses practical applications of magnets, including the floating compass, and proposes a new design for a pivoted compass. This work is considered a foundational text in the science of magnetism and a precursor to modern scientific methods.12