Natural speed please
Conan Doyle was friends for a time with Harry Houdini, the American magician who himself became a prominent opponent of the Spiritualist movement in the 1920s following the death of his beloved mother. Although Houdini insisted that Spiritualist mediums employed trickery (and consistently exposed them as frauds), Conan Doyle became convinced that Houdini himself possessed supernatural powers—a view expressed in Conan Doyle's The Edge of the Unknown. Houdini was apparently unable to convince Conan Doyle that his feats were simply illusions, leading to a bitter public falling out between the two.
Conan Doyle was also a passionate advocate for diverse causes: in 1906 and 1908 he began investigating two closed cases until he obtained the exoneration of the innocent men.
By 1920 Doyle was one of the most highly paid writers in the world. He died of a heart attack in 1930; he was 71 years old.
