Houdini's "Margie Box"
Mediums had no greater opponent than magician Harry Houdini, who denounced them as frauds. In fact, he had almost a secondary career debunking the methods of famous mediums during séances and performing their tricks as part of his stage show. He even asked his wife to help him show how mediums pull off certain tricks.
In 1924, Houdini was part of a committee investigating Boston medium Mina "Margery" Crandon, the wife of a respected surgeon and Harvard faculty member. Crandon had entered herself in a contest of sorts, run by Scientific American, that offered a monetary prize to the medium able to produce a "visual psychic manifestation." Here, Houdini is shown in the "Margie Box," which was intended to limit the medium's physical movements within the séance room and contain her suspected manipulations; Houdini built the box himself. The committee sat in on 20 séances, and the debate about Crandon's abilities lasted for a year, but ultimately, Scientific American opted not to award her the money