Florence Cook

By the time William Crookes began sitting with Florence Cook in 1874, materialisation seances built around a spirit called Katie King had already circulated through the London spiritualist circuit for several years, associated at different points with more than one medium. Cook's version of the phenomenon followed a standard form: she was tied into a curtained cabinet, sometimes with a rope sealed and inspected beforehand, and after a period the figure of Katie King, a young woman in white drapery, would emerge to walk among the sitters, speak, and occasionally be photographed, while Cook herself remained, by report, insensible inside the cabinet throughout.

Crookes brought instruments and his own scientific reputation to the sittings, took a series of photographs using magnesium light, and at points arranged to see Cook and the materialised figure in view at the same time, a test meant to rule out the simplest explanation that Cook herself was simply dressing as Katie King. He published his conclusion that the phenomena were genuine, and the endorsement of a Fellow of the Royal Society lent the case a scientific weight that testimony from less credentialed sitters never achieved.

Critics from the outset pointed to the limits of the test: the conditions were largely set at Crookes's own house, under his own arrangements, with Cook's cooperation throughout, and the moments in which Cook and Katie King were supposedly seen together were brief and dimly lit. Whether the investigation ruled out substitution or simply failed to catch it has been argued ever since, and the atlas records both readings rather than adopting either.

Two incidents bracket Cook's career and are usually read as pointing in opposite directions from the Crookes sittings. In 1873, before Crookes's investigation began, the collector William Volckman seized the materialised Katie King mid-seance and claimed the figure was Cook herself; the sitting ended in confusion, Cook's supporters accused Volckman of assault, and no independent examination settled the question either way. Crookes began his own sittings not long afterward, and his eventual endorsement is sometimes read as a direct rebuttal of the Volckman incident, an attempt to test properly what Volckman's grab had only asserted.

The more damaging incident came in 1880, well after Cook's reputation had moved on from the Katie King sittings to further materialisation work under her married name, Florence Corner. At a sitting hosted by Sir Charles Blandford, the young writer George Sitwell seized the materialised spirit and found, by his account and that of other witnesses present, Florence Cook herself, wearing only a chemise over her ordinary clothing where the drapery should have been. Unlike the Volckman incident, this exposure was witnessed by multiple observers in circumstances contemporaries treated as considerably harder to explain away, and it effectively ended her standing as a credible physical medium even among sympathetic spiritualist circles.

Historians who have revisited the case note that Cook continued to attract sitters afterward, which some read as evidence of a devoted following unmoved by exposure and others read as evidence of how little a single damning incident could dislodge belief already invested in a medium's gifts.