Slade, Dr. Henry

Slade, Dr. Henry One of the most famous Slate-Writing mediums during the 19th century. Henry Slade (the “Dr.” apparently was adopted for effect) was so adept at producing slate phenomena that scientists, journalists, royalty and even magicians came to believe in Spiritualism.

Slade’s birth and early life are not known. But following the epidemic of mediumistic discovery in the 1850s, Slade began holding Séances in New York City about 1860–61, working in that city for 15 years. In 1876, the Grand Duke Constantine of Russia asked Theosophists Madame Helena P. Blavatsky and Colonel Henry Steel Olcott to find a suitable medium for psychic investigation by the Imperial University of St. Petersburg. After a series of tests, Blavatsky and Olcott chose Slade, who left for Europe in July.

He arrived in London on July 13 and decided to remain a while to educate the British public about the wonders of slate phenomena. He gave Séances in his rooms at Russell Square, amazing sitters with writing on sealed slates, materialized hands and even levitation. A reporter from the London World wrote that he felt spirit pinches, saw ghostly hands, heard violent Rappings, and read various messages on the slates, all in full light.

Various eminent scientists and men of letters sat with Slade, and nearly all were won over. The great naturalist Alfred Russel Wallace believed completely in Slade’s powers, as did Rev. William Stainton Moses. Even a doubter like psychical researcher Frank Podmore, a founder of the Society for Psychical Research (SPR) in London, found the manifestations miraculous.

But not everyone was convinced. In September, E. Ray Lankester, professor of zoology at University College, London, and Dr. Horatio B. Donkin, a physician at Westminster Hospital, determined to unmask Slade. Lankester had been a member of the Selecting Committee of the British Association for the Advancement of Science but had left when the group accepted a paper on spiritualism written by Sir William Barrett. Lankester and Donkin each paid a pound for admission to the Séance. Before the climax of the sitting, Lankester seized a slate and found writing on it before it was supposed to appear. He submitted the exposure to the London Times and brought charges against Slade under the Vagrancy Act for taking money under false pretenses.

The case stirred passionate controversy. Spiritualists, led by Wallace, maintained that the spirits follow no schedule and could have penned the message at any time during the Séance. But when the case came to trial at the Bow Street Police Court on October 1, the magistrate, albeit impressed with the volume of spiritualist support, ruled that he must judge based on the known course of nature. He convicted Slade and sentenced him to three months’ imprisonment with hard labour.

Slade was released on bail pending appeal. When the case was reheard, the conviction was overturned on a technicality. His health in decline, Slade hurriedly left England for the Continent before Lankester could issue an other summons.

His plans to tour France were blocked by published accounts in Paris of his English exposure, so Slade proceeded to The Hague for a rest. From there he appealed to Lankester for a chance to prove his innocence, but the professor declined. Slade next travelled to Germany, where he mystified the court conjurer, Samuel Bellachini. He appeared in Denmark, then finally sat for the Grand Duke Constantine in St. Petersburg.

In December 1877, Slade submitted to rigorous investigation by Johann Zollner, professor of physics and astronomy at the University of Leipzig. Assisted by three other professors, Zollner became completely convinced of the genuine nature of Slade’s manifestations. He published his findings in Transcendental Physics, which was translated into English by C. C. Massey and published in 1880. Years later the Seybert Commission, charged with investigating every facet of spiritualism, discredited Zollner’s work.

Slade toured Australia after sitting for Zollner, then returned to America. In 1885, Slade sat for the Seybert Commission in Philadelphia. They found him guilty of fraud. In 1886, Slade and his business manager were arrested for deceiving the public in Weston, West Virginia. They were later released without prosecution.

In 1883, John W. Truesdell published an exposé of Slade in his book Bottom Facts of Spiritualism. Posing as Sam Johnson of Rome, New York, Truesdell attended a Séance with Slade. He purposely left an unsealed letter in his overcoat pocket, knowing it would be searched for clues, and snooped around the Séance room before the sitting. Finding a pre-written slate under the sideboard, Truesdell added the message: “Henry, look out for this fellow. He is up to snuff—Alcinda.” Alcinda was the name of Slade’s deceased wife.

During the Séance, a message from “Mary Johnson,” purportedly Sam’s sister, appeared. Truesdell, alias Johnson, said that was incorrect, and Slade surreptitiously drew the Séance table over to the sideboard. He stealthily retrieved the prepared slate, and he became enraged when he saw the additional message. Demanding to know who had done such a thing, Truesdell answered, “Spirits.” After a pause, Slade continued as if nothing had happened.

Slade’s career deteriorated rapidly after such bad publicity. He died penniless, an alcoholic and mentally unstable, in a Michigan sanatorium in 1905.



  • Doyle, Sir Arthur Conan. The History of Spiritualism Vol. I & II. New York: Arno Press, 1975.
  • Fodor, Nandor. An Encyclopedia of Psychic Science. Secaucus, N.J.: The Citadel Press, 1966. First published 1933.
  • Houdini, Harry. Houdini: A Magician Among the Spirits. New York: Arno Press, 1972.
  • Oppenheim, Janet. The Other World: Spiritualism and Psychical Research in England 1850–1914. New York: Cambridge University Press, 1985.
  • Podmore, Frank. Mediums of the Nineteenth Century. New Hyde Park, N.Y.: University Books, 1963. First published as Modern Spiritualism, London, 1902.


The Encyclopedia of Ghosts and Spirits– Written by Rosemary Ellen Guiley – September 1, 2007