He even toured the US, offering $10,000 to anyone who could demonstrate supernatural powers he could not replicate with Earthly means. 

Sherlock Holmes would have snorted contemptuously at his author’s theories as Conan Doyle came to the opinion that Houdini could not have accomplished several of the escape acts without resorting to the supernatural.  He even saw Houdini’s debunking of spiritualists as evidence that the magician could block others’ abilities. 

Both Houdini and Doyle continue to fascinate to this day, and collectors are always eager to purchase items that bring reality to an era that the majority of us will only read about.