
IT WAS nothing short of astonishing. In 1877, word began to spread that a team of internationally renowned scientists had witnessed empirical proof of a fourth spatial dimension populated by the souls of the dead.
The luminaries, at the University of Leipzig in Germany, included Wilhelm Weber, inventor of the electromagnetic telegraph, psychophysics pioneer Gustav Fechner, Johann Zöllner, the universityâs chair of astrophysics, and Wilhelm Wundt, who would later be dubbed the âfather of experimental psychologyâ.
How did they come to believe what we might now think of as âalternative factsâ, controversial even then? They had been persuaded by an American con man, a self-proclaimed spirit medium called âDrâ Henry Slade. His ability to convince and confound showed up the fractious state of science in the 19th century. Even Charles Darwin and Alfred Russel Wallace, pioneers of the theory of evolution, were pulled into Sladeâs orbit â albeit in opposite ways.
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The apparent proof of Sladeâs abilities, and therefore of the supernatural, involved a series of 30 seances. They were held in Leipzig over the winter of 1877 and spring of 1878 with the universityâs best and brightest in attendance. Zöllner quickly wrote them up in the book , and although he described them as âexperimentsâ, in truth they were chaotic affairs. Slade claimed to have no direct control over his powers, so while he often failed to provide the scientists with the intended results, something incredible usually happened.
Slade first impressed the Leipzig luminaries by deflecting a compass needle with only a wave of his bare hand. Later, as the men sat in a circle holding hands, objects in the room winked into and out of existence. Impossible knots appeared in lengths of cord. Lights flickered. Other times, rapping noises and music could be heard. Books and furniture might be flung about by mysterious forces. During one sitting, a bed screen behind Slade cracked in half, a feat the physicists estimated would have required the strength of two horses. Then, the words âIt was not our intention to do harmâ mysteriously appeared on a slate that the scientists had cleaned themselves and would swear that Slade had not even touched.
Looking back, it can feel easy to dismiss Zöllnerâs experiments as products of gullibility and accomplished trickery, but researchers are still discovering ways that and and reasoning. And Slade was a persuasive man. Once described by a reporter as having â, an 18th-century Derren Brown, but with a luxuriant moustache and no scruples. Slade had seized a golden opportunity, with spiritualism in its ascendancy in the late 1800s and combining an alternative Christian movement with emerging scientific and pseudoscientific concepts. High-profile proponents, including Arthur Conan Doyle, pointed to advances in the science of invisible forces such as electricity and magnetism to argue that mediums could provide empirical evidence of a soulâs survival beyond death. One might imagine that Conan Doyleâs signature character, Sherlock Holmes, would have disagreed.
Sladeâs rise to fame began before his trip to Leipzig, when he decided to embark on a world tour of psychic demonstrations accompanied, he claimed, by the spirit of his deceased wife, Alcinda. During his performances, he would receive communications from âAllieâ, and other souls, as written messages that mysteriously appeared on slates.
At his first stop, in London, he narrowly escaped being imprisoned for fraud. in the autumn of 1876 drew huge crowds and international media attention. And because spiritualism co-opted the language of scientific revolutions, its rise led to schisms not only in the general population, but also the scientific community. Darwin himself contributed the legal fees necessary to bring charges against Slade, whereas Wallace â who had been taken in by Sladeâs performances â spoke in his defence (a decision that did little for his reputation).
No miracle
Magician John Nevil Maskelyne was called to the stand to show that Sladeâs miracles could be reproduced by way of magic tricks. Slade declined to demonstrate his powers in the courtroom; Alcinda considered the proceedings âundignifiedâ, apparently. Sladeâs attorney, Mr Munton, managed to get Maskelyneâs testimony dismissed, arguing that just because the magician could produce effects that looked like the miracles, it didnât follow that Slade himself used trickery.

Late in the trial, Munton invited the judge to consider Slade in the light of other scientific revolutionaries â if the court convicted Slade for claiming to speak to the dead, then they were akin to the church officials who had imprisoned Galileo for asserting that Earth orbited the sun. âWhat is laughed at today,â he warned, âmight be very differently regarded tomorrowâ. The judge wasnât buying it, and sentenced Slade to hard labour and three monthsâ imprisonment for using â or device, by palmistry or otherwise, to deceive and impose on any of his majestyâs subjectsâ. But luckily for Slade, the conviction was overturned on a technicality, and he fled to continental Europe before he could be retried. This is where he encountered budding spiritualist Zöllner and his colleagues.
Zöllner came to believe that Sladeâs miracles represented empirical evidence of an . He theorised in Transcendental Physics that souls of the dead resided in this dimension, where they were unbound by our usual laws of three-dimensional space. In this way, he accounted for many of Sladeâs âmiraclesâ: for example, the vanishing objects didnât really vanish, but were simply rotated into the fourth dimension. It was an elegant physical explanation, but entirely reliant on Zöllnerâs belief that Slade was an honest gentleman.
Of all the scientists who witnessed Slade in action during his time in Leipzig, only one would publicly accuse him of dishonesty â one of the universityâs newest faculty members, Wilhelm Wundt. Following the publication of Zöllnerâs preliminary conclusions, Wundt wrote a called âSpiritualism as a Scientific Questionâ, which criticised spiritualist interpretation of the seances and proposed that they might better be attributed to âjuggleryâ or sleight of hand.
âOne theory was that objects didnât vanish, they rotated into the fourth dimensionâ
Whereas Zöllner had argued that scientists were the best people to assess Slade because they were trained physical observers, Wundt proposed they might not be the most qualified to detect deception. When Slade deflected the compass needle with his hand, the scientists immediately began to consider the implications in terms of âmolecular currentsâ. Non-scientists, Wundt wrote, âwould scarcely have neglected to examine the coat-sleeves of the mediumâ looking for magnets. Zöllner countered with a blistering letter addressed to Wundt, in which he suggested that Wundt be imprisoned for slander and hypothesised that the magnetic forces surrounding Slade might have scrambled Wundtâs brain.
Wundt was not imprisoned, and nor was Zöllnerâs work with Slade ever embraced by the wider scientific establishment. Zöllner would subsequently collapse over his breakfast, dying of a stroke at the age of 47. Today, if heâs remembered at all, it is for his contributions to and not, as he had hoped, for solving the mystery of eternal life. Following Zöllnerâs death, Wundt took over his university budget to establish what would become the .
And what of Sladeâs legacy? In 1885, an investigative commission comprising magicians and scientists from the University of Pennsylvania would and . They concluded that his demonstrations were âso closely resembling fraud as to be indistinguishable from itâ. Slade continued to travel and practice, even briefly returning to England under an alias, but he would never again achieve the acclaim or notoriety that heâd had in London and Leipzig. Later in his life, his affinity with spirits got the better of him as he descended into alcoholism. He died . Four days later, ran a story that noted Slade had not yet returned from the dead.
This article appeared in print under the headline âHe blinded us with seanceâ