Locked Double Slates Used by Remigius Weiss to Expose Spirit Medium Henry Slade, as Profiled by Harry Houdini in сA Magician Among the Spirits.о Nineteenth century hinged wooden slates with incorporated iron lock and original key, being a piece of apparatus used to expose Henry SladeНs practice, from the session eventually eliciting the confession from Slade that Houdini, quoting from Weiss, reproduced in A Magician Among the Spirits (1924). 8 _ x 6 _о. Accompanied by a Typed Letter Signed by Houdini (Aug. 2, 1923) to Weiss relating to HoudiniНs inspection of the slates and to the signed confession that, Houdini writes, сbears out your story to me,о continuing to say сI will open [the slates] at my leisure.о In turn, the slates bear an inscription dated just days later in chalk by Houdini, faintly visible: сDr. Slade failed. Forty years later slates were opened by Houdini./Aug 7 1923.о Inside, the slates are inscribed by сW.W.о: сyour Slates are to [sic] small for our use _ we will do more same very soon.о Also with an 1880 ALS from an unknown New York correspondent of WeissНs, providing information on SladeНs criminal charges, relating that a conviction under the Vagrant Act in the Bow Street Police Court (London) in 1876 was reversed on appeal by сthe presiding Judge (Segt. Cox) [who] was himself a Spiritualist and a firm believer in Slade.о Provenance traced to Oscar Teale, whose 1931 typed note of authenticity is included, indicating that the slates were to be sent to Frederick Eugene Powell. After Powell the slates were acquired by John Henry Grossman, whose set of photographic glass slides showing interior and exterior views of the slates are included.