Museo Galileo
Virtual Museum
Lodestone armature
Lodestone armature

Natural magnets (lodestones) were often "armed," that is, encased in iron bands arranged so as to increase the stone's attractive force. In modern terms, the bands concentrated the lines of force of the magnetic field. The technique dates from the sixteenth century and was described by William Gilbert (1544-1603) in De Magnete (London, 1600).