The history of psychical research traces the systematic investigation of reported paranormal phenomena, spiritualist mediumship, telepathy, apparitions and hauntings, from the moment scholars first tried to apply disciplined evidence gathering to claims that had previously been either simply believed or simply dismissed. The Society for Psychical Research was founded in London in 1882 by a group of Cambridge academics including Henry Sidgwick, Frederic Myers and Edmund Gurney, who set out to collect and test reports of these phenomena with the same documentary rigor other Victorian scholars brought to any other subject, publishing detailed case investigations rather than either apologetics or ridicule.
The nineteenth century spiritualist movement and its mediums are a documented part of the history of new religious movements, and the Society's own investigations, which exposed a number of prominent mediums as fraudulent while leaving other cases formally unresolved, are the primary historical record of what was actually tested and what the tests found. The atlas relies on this documented history rather than either a movement's own claims or a skeptic's blanket dismissal when describing what nineteenth century investigators concluded about a specific medium or case.