From 1918 until his death in 1930, Arthur wrote eleven books proselytizing spiritualism, plus numerous pamphlets, articles, and letters to make his case. To spread the word, he lectured throughout Britain, the United States, Canada, Australia, New Zealand, and Africa. He opened his own psychic bookstore.

Strangely, he established a fractious friendship with Houdini, the great magician who spent so much time debunking claims of the supernatural, explaining and demonstrating how so-called psychic phenomena were nothing more than crude magic tricks. Though Houdini refused to reveal how he accomplished his own tricks, he never denied that they were accomplished by natural means.

Arthur, being unable to conceive of how Houdini accomplished his many escapes, simply concluded that Houdini was one of the great mediums of all times who accomplished his feats by supernatural means. In fact, Arthur deemed his insight to be a great discovery, one of which the world should be made aware. To Houdini’s biographer, Harold Kellock, Arthur wrote, “I think, however, that you may take the words ‘An Unsolved Mystery’ off your cover. It is I who have solved the mystery of Houdini and I have no more doubt that he used psychic powers than I have that I am dictating this letter.”

Arthur was fooled not only by young women with unusual appendages, by girls with scissors and a camera, and by a dog that wouldn’t stop yipping, he was fooled most thoroughly by himself. The creator of Sherlock Holmes must have been someone less silly and gullible than Arthur Conan Doyle.

More than three decades ago, I read a book by Martin Gardner called Science: Good, Bad, and Bogus (1981). It was a collection of his essays, and one of them in particular caught my attention. It was “The Irrelevance of Conan Doyle.” In that essay, Gardner argued that Arthur could not have created any character as rational and scientifically minded as Sherlock Holmes because Arthur was simply too gullible. Gardner did not provide any specific examples of Arthur’s gullibility, but he did allege that Arthur “spent the last twelve years of his life in a tireless crusade against science and rationality. … There is scarcely a page in any of Doyle’s books on the occult,” Gardner continued, “that does not reveal him to be the antithesis of Holmes. His gullibility was boundless. His comprehension of what constitutes scientific evidence was on a level with that of members of London’s flat-earth society.”

This interested me. Though Gardner provided no examples of Arthur’s credulity, I had no trouble discovering many on my own, and I’ll relate one of them here. In his book The History of Spiritualism (1926), Arthur discusses the astounding power of ectoplasm. Spiritualism is the belief that those of us remaining on earth can communicate with our forebears who have passed into the spirit world, but we can do so only through an especially gifted person called a medium. Ectoplasm is the material through which the spirits make themselves visible to us. In Spiritualism’s Victorian heyday, the best mediums exuded ectoplasm, hence spirits, from their “natural orifices,” to use Arthur’s delicate words. Of ectoplasm, Arthur wrote:

The substance itself emanates from the whole body of the medium, but especially from the natural orifices and the extremities, from the top of the head, from the breasts, and the tips of the fingers. […] The substance occurs in various forms, sometimes as ductile dough, sometimes as a true protoplasmic mass, sometimes in the form of numerous thin threads, sometimes as cords of various thickness, or as a broad band, as a membrane, as a fabric, or as a woven material, with indefinite and irregular outlines.

Arthur believed that female mediums could exude “psychic rods” from whatever natural orifice they might have beneath a tabletop, and that these rods could become firm enough to lift the table. He described this titillating phenomena in his Edge of the Unknown (1930).

In the Belfast experiments this same ectoplasm was used for the making of rods or columns of power, which protruded from the body of the unconscious girl, and produced results such as raps, or the movement of objects, at a distance from her. Such a rod of power might be applied, with a sucker attachment, under a table and lift it up, causing the weight of the table to be added to that of the medium, exactly as if she had produced the effect by a steel bar working as a cantilever and attached to her body.

Most mediums were female. They were investigated by some of the most famous scientists of the time, virtually all of whom were male. Given Victorian sensibilities, and given that ectoplasm was exuded from all the “natural orifices,” this gender dichotomy might have posed a problem of propriety. Fortunately, the female mediums and the male investigators were willing, for the sake of research, to overcome all obstacles. If science demanded that the medium perform in the nude or take her investigator as a lover, so be it. If science demanded that Arthur fondle the ectoplasmic phallus of a female medium, how then could Arthur decline? He describes one such fondling in his History of Spiritualism.

The author has frequently seen ectoplasm in its vaporous, but only once in its solid, form. That was a sitting with Eva C. under the charge of Madame Bisson. Upon that occasion this strange and variable substance appeared as a streak of material six inches long, not unlike a section of umbilical cord, embedded in the cloth of the dress in the region of the lower stomach. It was visible in good light, and the author was permitted to squeeze it between his fingers, when it gave the impression of a living substance, thrilling and shrinking under his touch. There was no possibility of deception on this occasion.

Finding so many examples of Arthur’s self-admitted silliness helped me better understand Gardner’s too-gullible-to-be-Sherlock’s-creator suspicion. Gardner, however, provided no solid proof of Arthur’s literary fraud, nor did Gardner offer any alternative to Arthur as Sherlock’s creator. He left that work to whomever among his readers might take up the gauntlet.