Diagrams, experimental equipment and results by John Hopkinson, E Wilson and Francis Lydall Three circuit diagrams, labelled figures 1-2 and figure 4, followed by ten pages of graphs of experimental results relating to Hopkinson, Wilson and Lydall's investigation into magnetic viscosity. Subject: Electromagnetism / Physics Prints of these diagrams were published in volume 53 of the Proceedings of the Royal Society alongside the paper 'Magnetic viscosity'. 1893