Two volumes: The first is a facsimile of the 48-page pamphlet in the Biblioteca Palafoxiana, Puebla, Mexico that appears to be a printed version (1631) of a lecture Atanasio Kircher had given while teaching at the Jesuit seminary in Heiligenstadt. The second volume is a translation from the original Latin into Castillian Spanish. The work is a mixture of descriptions of Kirchers own experiments and accounts drawn from classical authorities. He describes his own attempts to measure the force of a magnet by using a balance, relates how an eruption of Vesuvius caused magnetic needles to change direction, and wonders that a red-hot piece of iron is attracted by a magnet, although the magnet is not attracted by it. He also suggested that magnetism could serve as a basis for long-distance communication. He cited the works of Pliny and Plutarch and suggested conserving a magnets strength by wrapping it in dried woad leaves. He warned that leaving a magnet near a diamond or rubbing it with g