Digital Clairvoyance: Lessons Learned by Text Mining the “Dr Slade Number” from 1876

The American medium Henry Slade was a nineteenth-century sensation. At the height of his career in the early 1870s he was considered one of the most extraordinary psychics of his generation. His main performance featured a type of supernormal communication where written messages, said to be from spirits existing beyond the veil, appeared on supposedly blank slates. It was a hugely popular act, and Slade toured all over North America and Europe demonstrating his incredible mediumship to broad and eager audiences. However, when Slade arrived in England during the autumn of 1876, his luck changed considerably. During a sitting at his apartment in London in mid-September with the naturalist E. Ray Lankester and the physician Horatio Bryan Donkin, the séance was abruptly cut short when the supposedly blank slate in Slade’s hand was seized to reveal that there was a pre-recorded message already written on it. After this sitting, a media sensation erupted in the press.[1]

Enraged by the discovery, Lankester led a public campaign to destroy Slade’s reputation. He published a series of damning letters in The Times between the 16th and 23rd of September 1876 declaring Slade to be an utter Charlatan.[2] Coverage of the affair appeared throughout the Victorian periodical press, and all kinds of influential figures weighed in on the conversation as a result of Lankester’s accusation [see Figure 1]. Some, like the naturalist Alfred Russel Wallace, defended Slade and proclaimed his supernormal powers to be real.[3] Others, like the inventor John Algernon Clarke, asserted that Slade’s mediumship was fake. As a close collaborator of the famed Victorian magician John Neville Maskelyne, Clarke positioned himself as an expert in detecting well-crafted illusions. In his view, Slade’s séances were nothing more than a skilled performance in misdirection and legerdemain.[4] Eventually, Lankester went to the police, and Slade was indicted under the terms of the Vagrancy Act of 1824. This law stated that it was illegal in Britain for a person to use any “subtle craft, means, or device by palmistry or otherwise,” to deceive people.[5] Slade was summoned to court, and a trial was held throughout October of 1876. Slade was ultimately found guilty, but an error in the original paperwork submitted to the court by Lankester enabled his defense lawyers to win an appeal. Before a retrial could take place, Slade fled England to avoid further prosecution.

Figure 1. Anon., ‘Prosecution of the Spirit-Medium Slade,’ Illustrated London News, 7 October 1876.

The story of Slade’s downfall during his stay in England in the autumn of 1876 is famous today, especially among Victorianists interested in the history of modern spiritualism and psychical research. Mention of Slade’s trial is sprinkled throughout the historiography.[6] However, as we enter a new age of scholarship, where text mining software like Voyant enables us to dig deeper into well-known historical cases, it is high-time we consider what these digital tools can potentially unearth that will change or enhance our understanding and interpretation of famous stories like Slade’s exposure. Voyant is an especially useful software because it does not require any coding. Therefore, even a novice in digital humanities studies can use it. What follows are some initial impressions of the kinds of data recovered from a preliminary search of material related to the Slade case.

Text mining is a useful method for analyzing both the structure and presentation of a source. Many of the stories about supposed instances of spirit and psychic phenomena that appeared in the extant literature during the height of spiritualism are carefully crafted narratives. The evidence used to confirm the reality of spirit and psychic manifestations was often highly suspect. Both believers and sceptics alike worked hard to either legitimize or delegitimize accounts.[7] The minute details of witness testimonies were heavily scrutinized, and therefore writers took great pains to present cast-iron cases. With text mining software we can completely deconstruct how writers framed their portrayals of important spiritualist events like Slade’s supposed exposure in 1876. As a tool for micro-historical investigations, it is possible to produce a rich ‘thick description’ of a text, to borrow the term from Clifford Geertz.[8]

To test the value of using software like Voyant, I text mined a special issue of the spiritualist periodical The Medium and Daybreak from 1876 that was completely devoted to a defence of Slade during the period of his trial. This issue was titled ‘The Dr Slade Number’ and was published on 6 October 1876 [see Figure 2]. Proceeds from its sale were to be used for Slade’s legal fees. The Medium and Daybreak was one of the main spiritualist publications in Victorian Britain. Its editor was James Burns, a prolific figure within the British spiritualist movement. In addition to founding the Burns Spiritualist Institution in 1863, which was a central hub for spiritualist activities in London, Burns originally founded the periodical The Medium in 1869. Later that year his periodical merged with another spiritualist publication titled Daybreak to form The Medium and Daybreak, which continued to produce issues until 1895.[9]

Figure 2. Front Cover to the ‘The Dr Slade Number’ produced by the periodical The Medium and Daybreak, 6 October 1876 [10]
For those who have never used Voyant before, one of the chief features of the software is the ability to create word maps of the most used terms in any given corpus. In this case, I instructed Voyant to create a map that highlighted the top twenty-five most used words in ‘The Dr Slade Number’ [see Figure 3]. If you were already familiar with the Slade story, the results are fairly predictable.

Figure 3. Word map generated by Voyant that highlights the top twenty-five most used words in ‘The Dr Slade Number’ of The Medium and Daybreak from October 1876.

The larger the font in the word map, the more frequently the word is used in the text. If we focus solely on the ten largest words, we can dig even deeper to reveal more about the kind of language used to frame the case in ‘The Dr Slade Number.’ The word ‘tho’ appears most frequently in the text at 151 times. However, this is a mistranslation by the software’s optical character recognition reader (OCR). Voyant produces a list that allows you to see how a selected word (in this case ‘tho’) appears throughout the text. You can use this function to zoom in on each of the sentences where the word is used for a closer reading. By clicking on the link, it was clear that the word ‘the’ was repeatedly mistranslated as ‘tho.’ Such an error by the OCR reader certainly raises some concern about what else the software might be misreading during the text mining process. Therefore, it is highly advantageous to compare the results from Voyant searches with those of a searchable PDF of the original text.

A more revealing result from the text mining data is the second most frequently used word in ‘The Dr Slade Number,’ which is ‘Dr.’ It appears 145 times in the text. This connects to my earlier remark on how writers of spiritualism produced carefully crafted narratives about events, figures, investigatory techniques, et cetera. Burns, who edited the special issue, was a chief proponent of the spiritualist movement in Britain, and a staunch supporter of Slade’s mediumship. He routinely refers to Slade as ‘Dr Slade,’ and this is no minor detail. There is zero evidence that Slade earned a degree in medicine or receive a doctorate from a university. His title was fake, but it served to frame him as a more trustworthy and authoritative figure. To a certain degree, we can think of it as an exercise in ‘virtue epistemics.’[11] By repeatedly positioning Slade as a kind of scientific figure, he became a more reliable subject. It implied that Slade was credible because he was also a doctor. The repeated emphasis on calling him ‘Dr Slade’ throughout the issue, which was designed to defend the medium’s reputation at the time of the trial, was done to reinforce his status among the spiritualist community as a credible practitioner.

Another useful feature in Voyant is the word link infographic tool. This allows the user to trace connections between the most used terms in a corpus, with a function to have an even closer look at these links in the sentences from the text. Once again, the tool allows us to closely inspect the way contributors to ‘The Dr Slade Number’ carefully framed the story in their narratives. Take for example the word ‘table,’ which appears 84 times in the text. The most common word links according to the infographic are ‘place’, ‘slate,’ ‘top,’ ‘Slade,’ and ‘hand’ [see Figure 4].

Figure 4. Word link map showing the most common connections in ‘The Dr Slade Number’ to the word ‘table.’

For those familiar with how Slade organised his séances, these word connections make a lot of sense. At a typical Slade séance, visitors would sit around a small loo table in the medium’s parlour. Usually, Slade would sit in a chair with his back to the light, which meant that his body was cast into shadow. During the main part of his séance, where spirit writing was produced, the slates were often held together in the hands of both Slade and one of his sitters, or pressed tightly against the top of the table. Thus, we can already begin to make sense of the connections highlighted in the word link infographic. Specific information on how everything was placed during the spirit writing process was also carefully recorded in every witness account. Thus, the connection between the words in the infographic for ‘table’ more or less matches the general narrative of Slade’s mediumship and reinforces the canonical story about Slade’s séances.

In addition to the data recovered through the word link infographics, the user can also map the linkages against the sentences in the text. For example, the words ‘table’ and ‘hands’ are connected 54 times in ‘The Dr Slade Number.’ Upon a closer inspection of the word pairing, we learn that the connections are not always in relation to the slate writing phenomenon, but other manifestations as well. Take, for example, a witness account of a sitting with Slade that was published in The Medium and Daybreak’s special issue. It was written by a woman named Louisa Andrews, who had organised a sitting with Slade and her sister earlier in the autumn of 1876. Andrews described in detail some of the other kinds of extraordinary occurrences to be produced by Slade during the séance:

Not only did blows, almost deafening in the noise they made, fall close to our hands upon the table, while at the same moment hands were pounding upon the keys of the piano, but we heard something heavy dragged over the floor, and after the sitting, found that the instrument had been moved from its place and brought close up to us, while the stool was upon the table, almost touching our hands. [12]

As we can see, by looking closer at the text, the connection between ‘table’ and ‘hands’ reveals other experiences to be witnessed at Slade’s sittings; including auditory and physical manifestations. By combining the infographic data, with the close reading function of Voyant, a more textured picture of Slade’s mediumship emerges. As a tool for both micro-historical research and close textual analysis, Voyant certainly enhances what a researcher can uncover in a text through a highly systematic approach.

These findings are only some initial impressions of what tools like Voyant can offer to scholars interested not just in the history of spiritualism, but in Victorian print culture more generally. Through this cursory examination of a single issue of The Medium and Daybreak from October of 1876, I have been able to visually map some of the ways spiritualists in support of Slade’s mediumship attempted to carefully craft narratives about the legitimacy of his supposed supernormal powers. Much of what was uncovered in this initial scoping exercise aligns with the details of the canonical story. Therefore, at a rudimentary level, what this test using Voyant unearthed is further data to reinforce the well-known account. However, other details come to the fore as well. Most of the studies to explore Slade’s mediumship tend to focus on his spirit writing. However, an examination of Voyant’s word link infographics highlighted other incredible feats such as auditory phenomena like loud knocks on the table, and furniture moving around the room without any apparent human agency involved. Thus, an expanded picture of Slade’s mediumship begins to form. Text mining tools such as Voyant will become a staple of Victorian print culture studies in the years ahead, and I look forward to learning what else will be uncovered as we move further into this new digital age of scholarship.

Efram Sera-Shriar (@DrEframSS / is a historical anthropologist who specialises in Victorian science and studies of the occult. He is an Associate Professor in the history and culture of the English-speaking world at the University of Copenhagen. Sera-Shriar is the author of Psychic Investigators: Anthropology, Modern Spiritualism, and Credible Witnessing in the Late Victorian Age and The Making of British Anthropology, 1813–1871. He has been a senior editor for the John Tyndall Correspondence Project since its inception. Sera-Shriar’s current work explores the relationship between popular occulture, science, and the media since the late Victorian age. 

Notes & references

[1] Joseph Lester, E. Ray Lankester and the Making of Modern Biology, (Farringdon: British Society for the History of Science, 1995), 93-104.

[2] E. Ray Lankester, Horatio B. Donkin, and Alice Lane Fox, ‘A Spirit Medium,’ The Times, 16 September, Issue 28736 (1876), 7; E. Ray Lankester and Henry Slade, ‘A Spirit Medium,’ The Times, 21 September, Issue 28740 (1876), 3; E. Ray Lankester, Horatio B. Donkin, and Henry Slade, ‘A Spirit Medium,’ The Times, 23 September, Issue 28742 (1876), 9.

[3] Alfred Russel Wallace, R. A. Joy, and George C. Joad, ‘A Spirit Medium,’ The Times, 19 September, Issue 28738 (1876), 4.

[4] Charles Carter-Blake, C. C. Massey., and John Algernon Clarke, ‘A Spirit Medium,’ 18 September, The Times, Issue 28737 (1876), 6.

[5] Anonymous, “Conviction of Dr. Slade,” The Hull Packet and East Riding Times, 4758 (1876): 3.

[6] For example, Janet Oppenheim, The Other World: Spiritualism and Psychical Research in England, 1850-1914, (Cambridge: Cambridge University Press, 1985); Alex Owen, The Darkened Room: Women, Power and Spiritualism in Late Victorian England, (London: Virago Press, 1989); Peter Lamont, The First Psychic: The Extraordinary Mystery of a Notorious Victorian Wizard, (Preston: Abacus Books, 2005).

[7] Efram Sera-Shriar, Psychic Investigators: Anthropology, Modern Spiritualism, & Credible Witnessing in the Late Victorian Age, (Pittsburgh: University of Pittsburgh Press, 2022), 6-7.

[8] Clifford Geertz, The Interpretation of Cultures, (New York: Basic Books, 1973), 25-56.

[9] Geoffrey Nelson, Spiritualism and Society, (Abingdon: Routledge, 1969), 99-100.

[10] James Burns (ed.), ‘The Dr Slade Number,’ The Medium and Daybreak, 3 (1876).

[11] Lorraine Daston and Peter Galison Objectivity, (New York: Zone Books, 2007), 39-42.

[12] Louisa Andrews, ‘Phenomena in the Presence of Dr Slade,’ The Medium and Daybreak, 3 (1876), 629.

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