Galileo presented this magnet to Ferdinand II, as witnessed by Benedetto Castelli: "I have seen a piece of lodestone of six ounces only armed with iron with exquisite care by Signor Galileo and donated to the Most Serene Grand Duke Ferdinand, which supports fifteen pounds of iron fashioned in the shape of a sepulchre" (Discorso sopra la calamita, Ms Galil. 111, c.203v. Biblioteca Nazionale Centrale, Florence).
Galileo's studies on magnetism intensified between 1600 and 1609. In particular, Galileo discussed magnets with Paolo Sarpi and Giovanfrancesco Sagredo, between Padua and Venice, during that decade. Their exchanges frequently refer to William Gilbert's De Magnete (London, 1600).