Editing Magnetic field (section)

===Early developments===
While magnets and some properties of magnetism were known to ancient societies, the research of magnetic fields began in 1269 when French scholar [[Petrus Peregrinus de Maricourt]] mapped out the magnetic field on the surface of a spherical magnet using iron needles. Noting the resulting field lines crossed at two points he named those points "poles" in analogy to Earth's poles. He also articulated the principle that magnets always have both a north and south pole, no matter how finely one slices them.<ref>{{cite book | doi=10.1007/978-1-4020-4423-6_261 | chapter=Peregrinus, Petrus (Flourished 1269) | title=Encyclopedia of Geomagnetism and Paleomagnetism | date=2007 | last1=Chapman | first1=Allan | pages=808–809 | publisher=Springer | location=Dordrecht | isbn=978-1-4020-3992-8 }}</ref>{{refn|group="note"|His ''Epistola Petri Peregrini de Maricourt ad Sygerum de Foucaucourt Militem de Magnete'', which is often shortened to ''Epistola de magnete'', is dated 1269 C.E.}}

Almost three centuries later, [[William Gilbert (astronomer)|William Gilbert]] of [[Colchester]] replicated Petrus Peregrinus' work and was the first to state explicitly that Earth is a magnet.<ref name=Whittaker1910>{{cite book|last=Whittaker|first=E. T.| author-link=E. T. Whittaker|title=[[A History of the Theories of Aether and Electricity]]|year=1910|publisher=[[Dover Publications]] | isbn=978-0-486-26126-3}}</ref>{{rp|34}} Published in 1600, Gilbert's work, ''[[De Magnete]]'', helped to establish magnetism as a science.