The 19th and early 20th century was an age of wonder for spirit mediums and those believing in their power to communicate with the dead. Although belief in spirits and the supernatural goes back for thousands of years, the Spiritualist movement seemed to reach the peak of its influence from the 1840s to the 1920s. Séances were held in private homes and drawing rooms across Europe and North America and phenomena such as automatic writing, table tipping, and spirit rapping were common.   The popularity of spiritualism seemed to stem from the famous converts who attended séances and testified to what they saw and heard. While early sceptics raised the inevitable suggestion that trickery was being used, the believers, often-trained men of science themselves, were quick to insist that they would spot anything fraudulent. After all, eminent scientists such as Alfred Russel Wallace, William Crookes, William James, and Charles Richet couldn’t possibly be fooled, could they?

While mediums such as the Fox Sisters, Donald Douglas Hume, and Eusapia Palladino became international celebrities, there was one medium who was definitely in a class by himself: Dr. Henry Slade.   Born in 1835 in Johnson’s Creek, New York, actual details of his early childhood remain scarce (except for the elaborate biography he wrote for himself of course). According to Slade’s own grandiose description of his origins, he began showing signs of his strange power from the age of eight and progressed to doing feats of levitation by his early teens. By 1855, he was well established as a medium and people from all over the country were coming to see his demonstrations.

What made Slade so unique was his invention of the phenomenon of slate writing.   Although other mediums would be quick to copy his methods, it was Slade who did it first.   In a typical slate writing session, Slade and the client (also known as a “sitter”) would take their seats at a small table while grasping the corners of an ordinary slate like the kind commonly used by schoolchildren.   The slate was held under the table and all lights were extinguished.   During the séance, writing sounds were heard and then a series of raps were heard at the end signaling that the message had been written. When the slate is exposed, a written message is found (usually in answer to a specific question on the part of the sitter).

Already calling himself “Dr.” Henry Slade by the time his career began in 1860 (although nobody knows where or how he acquired the advance degree that supposedly qualified him for the title), he became famous for his séances and his slate writing.   A bold showman, Slade publicly offered a $1000.00 reward for anyone who could prove that he was a fraud (a hefty sum in those days). It also helped that he was a handsome man with a charismatic manner that likely did as much to attract women patrons as his supposed mediumship powers. After deciding that Europe provided better opportunities, Slade went to London, England in 1876 and quickly began charging hundreds of pounds for his famous sittings.

Unfortunately, Slade eventually drew the attention of two arch-skeptics, Professor Ray Lankester and Dr. Horatio Donkin. Both men became suspicious of Slade’s methods and laid an elaborate trap for him.   Inventing a non-existent “Uncle John”, Lankester asked Slade for help in contacting his supposedly deceased relative. In an arranged séance, Slade was placing a supposedly blank slate under the table to prepare for the séance when Lankester snatched it out of his hands.   The “blank” slate already held the message from “Uncle John” that was supposed to have been written during the séance.   Armed with this evidence of fraud, Lankester and Donkin had Slade arrested.

It was a sensational trial and generated tremendous publicity across the United Kingdom.   Lankester and Donkin both testified against Slade. The star witness though, was magician John Nevil Maskelyne who successfully imitated all of Slade’s trick right there in the witness box.     Even support from the eminent Alfred Russel Wallace himself wasn’t enough to sway the jury in Slade’s favour. Based on the overwhelming evidence, Henry Slade was sentenced to three months hard labour.   The sentence was overturned on appeal based on a technicality and, while Lankester was arranging for a new trial, Slade and his manager fled to France.

While Slade was hoping that he could launch a new career in France, Lankester had arranged for a colleague to publish the entire account of the court proceedings in the French press.   Though his hopes for France ended quickly, he had better success in Germany where his trickery made a convert of Professor Johann Karl Zollner (who, ironically enough, is most famous for his work with optical illusions). With Zollner’s endorsement and the tacit support of many other German scientists (who largely relied on Zollner’s reputation rather than testing Slade for themselves), Henry Slade was back in business. Later writers have argued that Johann Zollner was half-senile at the time and his support of Slade represents a sad footnote on an otherwise glorious scientific career.

Despite further endorsements from famous theosophists such as Helena Blavatsky, Henry Slade’s career as a spiritualist definitely went downhill.   After appearing in St. Petersburg and holding séances with several prominent Russian academics and nobles, he was caught out in trickery several times (but still managed to make further converts). There was also a reference to his attempting to return to London in 1878 and holding séances under the name of “Dr. Watson” but he didn’t stay there long.

By 1884, Henry Slade was back in New York which, unfortunately for him, would be just in time for his last stand.   When Philadelphia philanthropist Henry Seybert died in 1882, he left a sizeable bequest to the University of Pennsylvania to set up a commission to investigate "all systems of Morals, Religion, or Philosophy which assume to represent the Truth, and particularly of Modern Spiritualism."   Although Seybert had been an ardent spiritualist, the outcome of the Seybert Commission was likely not what he had in mind with his bequest. The ten scholars who made up the Commission were recruited for their neutral stance on Spiritualism and psychic phenomenon.   From 1884 to 1887, the members of the Commission made it their mandate to investigate various mediums across the country. Henry Slade was among the mediums invited to be tested.

The Commission took a special interest in slate writing but none of the mediums that they investigated were able to stand up to their scientific scrutiny. Henry Slade in particular was disgraced when he was caught cheating.   In the scathing final report that the Commission released in 1887, they concluded that “our regret that thus far we have not been cheered in our investigations by the discovery of a single novel fact; but, undeterred by this discouragement, we trust with your permission to continue them with what thoroughness our future opportunities may allow, and with minds as sincerely and honestly open, as heretofore, to conviction”.

Henry Slade never recovered from this blow to his reputation and his career as a medium was effectively over. By 1892, he succumbed to alcoholism and one source described him as “an inmate of a workhouse in one of our Western towns, penniless, friendless, and a lunatic”.


Dr. Vitelli is a practicing psychologist from Hamilton, Ontario, Canada. He also writes "Providentia" (, a blog about psychology in today's world.