The British direct-voice medium Frederick Tansley Munnings was exposed as a fraud when one of his séance sitters turned the lights on which revealed him to be holding a trumpet by means of a telescopic extension piece and using an angle piece to change the auditory effect of his voice. Richard Hodgson held six sittings with the medium Rosina Thompson and came to the conclusion she was a fraud as he discovered Thompson had access to documents and information about her séance sitters.
The magician Julien Proskauer revealed that the levitating trumpet of Jack Webber was a trick. Close examination of photographs reveal Webber to be holding a telescopic reaching rod attached to the trumpet, and sitters in his séances only believed it to have levitated because the room was so dark they could not see the rod. Webber would cover the rod with crepe paper to disguise its real construction.
The physicist Kristian Birkeland exposed the fraud of the direct voice medium Etta Wriedt. Birkeland turned on the lights during a séance, snatched her trumpets and discovered that the "spirit" noises were caused by chemical explosions induced by potassium and water and in other cases by lycopodium powder. The British medium Isa Northage claimed to materialize the spirit of a surgeon known as Dr. Reynolds. When photographs taken of Reynolds were analyzed by researchers they discovered that Northage looked like Reynolds with a glued stage beard.
The fraudulent medium Ronald Edwin confessed he had duped his séance sitters and revealed the fraudulent methods he had used in his book Clock Without Hands (1955). The psychical researcher Tony Cornell investigated the mediumship of Alec Harris in 1955. During the séance "spirit" materializations emerged from a cabinet and walked around the room. Cornell wrote that a stomach rumble, nicotine smelling breath and a pulse gave it away that all the spirit figures were in fact Harris and that he had dressed up as each one behind the cabinet.
^ Paul Kurtz. (1985). A Skeptic's Handbook of Parapsychology. Prometheus Books. p. 29. ISBN 978-0-87975-300-9 "Florence Cook was caught cheating not only before her séances with Crookes but also afterward. Furthermore, she learned her trade from the mediums Frank Herne and Charles Williams, who were notorious for their cheating." Also see M. Lamar Keene. (1997). The Psychic Mafia. Prometheus Books. p. 64. ISBN 978-1-57392-161-9 "The most famous of materialization mediums, Florence Cook – though she managed to convince a scientist, Sir William Crookes, that she was genuine – was repeatedly exposed in fraud. Florence had been trained in the arts of the séance by Frank Herne, a well-known physical medium whose materializations were grabbed on more than one occasion and found to be the medium himself."
^ "Glossary of Key Words Frequently Used in Parapsychology" Archived 2010-12-24 at the Wayback Machine, Parapsychological Association website. "Materialization: A phenomenon of physical mediumship in which living entities or inanimate objects are caused to take form, sometimes from ectoplasm." Retrieved January 24, 2006 "Medium – Definition". Dictionary.com. Retrieved 23 March 2007.