TY - JOUR T1 - On the Existence of a Magnetic Medium JF - Proceedings of the Royal Society of London (1854-1905) VL - 7 SP - 448 EP - 454 PY - 1854/01/01/ UR - http://dx.doi.org/10.1098/rspl.1854.0105 M3 - doi:10.1098/rspl.1854.0105 AU - Hirst, T. ER -