An 1889 social survey inquiring into the frequency and nature of reported contacts with the dead. The census grew out of an early interest of the society for psychical research (SPR) in ghosts and apparitions. Among the first important works of the SPR was Phantasms of the Living (1886) by Edmond Gurney, Frederick William Henry MYERS, and Frank Podmore. It was built from the accounts of 702 people drawn from a random sample of 5,705 individuals. One major conclusion of the volume concerned the coincidence of apparitions and the death of the person seen in the apparition. Some responses to the book complained that the sample was too small. Thus, the SPR leadership decided to conduct a much larger survey.
The Census of Hallucinations canvased 17,000 individuals from whom 1,684 accounts of apparitions were received. The survey was compiled for publication by Eleanor Sedgwick, whose husband Henry Sedgwick chaired the committee in charge of the census. The results, which filled Volume 10 of the Proceedings of the SPR (1894), further confirmed the conclusions of Phantasms of the Living, and remain as one of the important accomplishments of psychical research. In 1899 French researcher Charles Richet conducted a similar survey with like results. The census did not address the objective nature of apparitions, an issue that continues to be debated to the present.