While the French Revolution was raging in the 1790s, in an abandoned crypt near Place Vendôme in Paris, a phantasmagoria took place every evening for three years. Doors remained locked for the whole duration of the show so that nobody could escape. Optical illusions and trompe-l’oeil effects filled a candlelit room, where Étienne-Gaspard Robert, known by the stage name of “Robertson”, would recite a monologue on death and the afterlife, surrounded by a smoky mix of sulphuric acid and aqua fortis, accompanied by ghostly apparitions. The show came to an end because it was investigated after complaints from audience members who feared Robertson would conjure back Louis XVI.

Phantasmagoria, literally “ghosts in the marketplace”, was a form of horror theatre consisting in the projection of frightening images – skeletons, demons, ghosts - with magic lanterns onto semi-transparent screens. Already popular in the early modern period, phantasmagoria and optical illusions became extremely popular in the eighteenth-century, when technical advancements diversified the range of available performing possibilities. 

In 1864, J.H. Brown published Spectropia or Surprising Spectral Illusions Showing Ghosts Everywhere and of Any Colour, an optical illusion book. Brown thought that spiritualism was a “mental epidemic” that confused visions with actual spirits. In Spectropia, Brown challenges readers to look at the images of variously coloured ghosts performing a variety of gestures and guises for about fifteen seconds without blinking. Turning one’s gaze at a wall soon after would make those same images appear inverted in colour and floating for an effect called ‘afterimage’. 

Despite the growing fascination with ghosts and spectres in the late-19^th century, scientism was still triumphant, at least among reviewers, who thought that the Brownian plates were “certainly very effective, and well designed for the purpose; but we should recommend an avoidance of needless horrors in future series. The grotesque and the beautiful will both work just as vividly as the ghastly, and several objects in the present series could not be judiciously introduced to the notice of boys and girls whose disposition was nervous, or whose superstitious feelings had been excited by injudicious nursery tales.”

Constantly crisscrossing the boundaries between magic and medicine, the fascination with ghosts underlied an oxymoronic desire to reify the invisible and dissolve the entrenchments of the ever-popular photographic medium at once. With the democratisation of photography in the late-19^th century, came an increase in the forms that ghosts could take on film, progressively moving away from the solid or corporeal towards the ethereal and eerie. In Chronicles of Spirit Photography, Georgiana Houghton (1814–1884), the prominent medium and artist championed by such influential figures as Sir Arthur Conan Doyle, brought forth the belief that contact with the spirit realm was possible and could bring one closer to God. Houghton pioneered the use of drawing as a method of channelling and expressing communications with spirit entities and worked closely with spirit photographer Frederick Hudson to sell reproductions of his photographs of entities invisible to the material eye. Similarly to Houghton, James Coates’ Photographing the Invisible showed what we now know to be images clipped from printing press sources such as newspapers, onto portraits of couples in their living rooms or of pensive people staring into the void. Coates led countless experiments in spirit photography and used what he called “mystery” as the basis of his “plastication” theory. He believed that ghosts in spirit photos were objects and not souls, postulating that spirit photography did not produce images of discarnate spirits, but rather supernaturally produced images of the deceased. 

Scientific was, instead, the language of Les vibrations de la vitalité humaine. Nerveux, sensitifs, névroses (1904) by the French doctor Hyppolyte Baraduc. Elaborating on the mental photographs he had made in the earlier stages of his career, Baraduc produced what he called the “biometre”, a tool with which he measured the invisible vital force emanating from a body. In 1903 he claimed that he “obtained photographs of love, hate, grief, fear, sympathy, piety etc. No new chemical is necessary to obtain these results. Any ordinary camera will do it.” He dedicated Les vibrations “exclusively to this all too special class of my contemporaries who vibrate in excess, poorly or not enough, to the nervous ones, to the impressionable, to the sensitive, to the misunderstood by materialist medicine”. Baraduc believed that “everyone of us has around himself his own and personal vortex of vibrations that expresses one’s vitality and defines the state of one’s soul whose sensibility and elasticity are measured by the portion of a circle; its length gives back an ideographic sense of the vibration itself: it is comparable to height for sound and brightness for colour: that vibration that animates us is alive, it is the momentary expression of universal life working within us, which manifests itself around us through a movement that moves the biometric tick by a number of degrees, proportionally to this movement.”

Transposing the medical into the religious, Charles Webster Leadbeater (1854-1934), a member of the Theosophical Society in London, elaborated a theory on human aura. He believed that particularly gifted people or clairvoyants were able to receive impressions on their eyes, which revealed them secrets about higher worlds. The colours of “thought forms”, as he called these intuitions, were associated with emotions, ranging from light blue (spirituality) to black (malice). Leadbeater gathered his studies in Man Visible and Invisible (1911), where his colour theory was laid out figuratively, bringing to the fore the friction between the aniconic and the illustrative underlying the same discourse dominating contemporary spirit photography.

All in all, ghosts proliferated between the 18^th and the 20^th centuries through the spectrality of phantasmagoria and spirit photography. Both recreated the emotional aura of the supernatural that technology had swept away at first. An invective against materialism became embedded in the evanescence of ghosts and ghastly figures disrupting mimesis and medicine. The reproducibility of the photographic medium facilitated the spread of the ghost on the marketplace through the twofoldedness of its very medium, at once indexical and ephemeral.