John Rennie wrote last week on the occasion of Houdini's birthday about the great magician's efforts to disabuse the spiritualist beliefs of Sir Arthur Conan Doyle, creater of Sherlock Holmes ("How did Houdini trick Conan Doyle?"). Rennie briefly describes the setup, which ends poorly:
Houdini then explained that he had done the whole thing through simple trickery and implored Conan Doyle to give up his spiritualist beliefs. Alas, he failed: not only did Conan Doyle continue to believe in mediums but he suspected that Houdini knowingly or unknowingly used his own supernatural gifts in the performance of his escape acts.
Not so surprising. As of yet, none of the commenters have worked out just how Houdini may have managed the trick that so convinced Conan Doyle of his psychic powers, involving magic writing of a secret message on a slate.