The medium Henry Slade was caught in fraud many times throughout his career. In a séance in 1876 in London Ray Lankester and Bryan Donkin snatched his slate before the "spirit" message was supposed to be written, and found the writing already there.[75] Slade also played an accordion with one hand under the table and claimed spirits would play it. The magician Chung Ling Soo revealed how Slade had performed the trick.[76]

In 1880 the American stage mentalist Washington Irving Bishop published a book revealing how mediums would use secret codes as the trick for their clairvoyant readings.[84] The Seybert Commission was a group of faculty at the University of Pennsylvania who in 1884–1887 exposed fraudulent mediums such as Pierre L. O. A. Keeler and Henry Slade.[85] The Fox sisters confessed to fraud in 1888. Margaret Fox revealed that she and her sister had produced the "spirit" rappings by cracking their toe joints.[86]
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