Sir William Crookes (1832–1919) was one of the most important experimental physicists of the 19th century: discoverer of the chemical element thallium (1861), inventor of the Crookes tube (the precursor of all cathode-ray devices, without which neither X-rays nor the electron could have been discovered) and of the Crookes radiometer. Knighted in 1897, Order of Merit 1910, President of the Royal Society 1913–1915. What is almost always missing from the textbook picture: between 1869 and 1875 Crookes investigated the most famous mediums of his time in his private London laboratory, with self-designed experimental apparatus – above all the Scottish levitation medium Daniel Dunglas Home and the young materialisation medium Florence Cook. Crookes never retracted his findings.
Who was William Crookes?
Crookes was born in 1832 as the son of a London tailor – without inherited wealth, without university access in the classical sense. He studied at the Royal College of Chemistry under August Wilhelm von Hofmann, built his own career as an autodidact, and in 1859 founded Chemical News, a specialist journal he edited himself for almost fifty years. In 1861 he discovered the element thallium through the spectral analysis of its green line – within the same year he was elected to the Royal Society.
An extraordinary career as an experimentalist followed. The Crookes tube (from 1869), an evacuated glass tube with high-voltage electrodes, was the instrument with which Wilhelm Conrad Röntgen discovered X-rays in 1895 and Joseph John Thomson discovered the electron in 1897. The Crookes radiometer ("light mill", 1873) can today still be seen in every physics cabinet. Royal honours followed: knighthood in 1897, Order of Merit 1910, and finally the presidency of the Royal Society from 1913 to 1915. Scientifically, then, Crookes was anything but an outsider.
Entry into the field (1867–1870)
The biographical trigger was a personal loss. In 1867 Crookes's younger brother Philip died at sea. Crookes himself described in later writings that he began attending séances in the wake of this loss – in the hope of contact with his brother. Within a few years this turned into something else: a systematic scientific research programme.
In 1870 Crookes published a programmatic essay in the Quarterly Journal of Science with the title Spiritualism Viewed by the Light of Modern Science. There he formulated what would become the methodological foundation of all his later work: phenomena that occur repeatably belong in the domain of science – independently of whether existing theory can explain them. A science that rejects observations because they do not fit into its theoretical building is no longer science.
Daniel Dunglas Home – the levitation medium
Crookes's most important "experimental subject" was Daniel Dunglas Home (1833–1886), a medium-star born in Scotland and raised in the United States, who toured the European courts – from Napoleon III to the Tsar – and was never caught cheating. Among 19th-century physical mediums this is exceptional. Even the otherwise extremely sceptical British historian Frank Podmore had to concede the point.
Crookes invited Home to his private laboratory on Mornington Road in London repeatedly between 1870 and 1873. Present alongside Crookes were regularly his brother Walter, the physician William Huggins (another FRS) and several guests with sober scientific backgrounds. What was observed under these conditions:
- Levitation of the medium: Home rose from the floor several times, in one case with his feet 30 cm above the table, in a room lit by gas. Crookes recorded the observations with time and a list of witnesses.
- Accordion playing in a cage: Home held an accordion at one end, inside a specially built, enclosed wire cage under the table. The accordion played tunes although no one could reach the keys. Crookes had designed and built the cage himself, so that no "free hand trick" was possible.
- Weight variations: A wooden board suspended on a stand, with its free end resting on a beam balance, showed measured weight changes of up to 6½ pounds without Home touching the board. The apparatus is illustrated in the original publications.
The apparatus: Crookes designs his own measuring instruments
What distinguishes Crookes from earlier investigators is his methodological strictness. He built his own measuring instruments to test whether the claimed phenomena were measurable – not merely "observable". The beam balance for weight measurement, the accordion cage, later an apparatus for measuring mental influence on an electrical circuit: all his own designs.
This approach structurally anticipates what J. B. Rhine would perfect at Duke from 1930 onwards, and the PEAR laboratory at Princeton from 1979: not "phenomenon yes/no", but quantitative measurement as method. Crookes is the grandfather of this line.
"Psychic Force": the controlled hypothesis
In July 1871 Crookes published in the Quarterly Journal of Science an essay entitled Experimental Investigation of a New Force. There he proposes to explain the observed phenomena as the effect of a new, hitherto unknown physical force, which he calls Psychic Force – a force that apparently emanates from particular persons and can act on matter.
"The phenomena I have investigated are so bizarre and so far from anything our present science can predict that only one very unwelcome assumption explains them all: that there is a new force, in some way connected with the human organism, which I will provisionally call the Psychic Force."
— William Crookes, Experimental Investigation of a New Force, 1871 (paraphrase, not verbatim)
Important: here Crookes does not speak of "spirits". He stays within a physical-scientific description. The same position appears later in Pierre Curie ("physical states of space of which we have no conception") and in Albert Einstein ("an extended physics is needed"). The line is consistent: top physicists of the 19th and early 20th century attempted to interpret mediumistic phenomena not spiritualistically but physically.
The Royal Society dispute and his career
The reaction of established physics was fierce. Crookes's essay was attacked in the press by the physiologist William Carpenter and the astronomer George Biddell Airy. The Royal Society rejected a detailed follow-up publication by Crookes. In contemporary caricature he appears as a man chasing after his scientific reputation while it floats away from him.
What is remarkable is what did not happen: Crookes's scientific career did not collapse. He remained Fellow of the Royal Society, received the Royal Medal in 1875, the Davy Medal in 1888, the knighthood in 1897. From 1896 to 1899 he was President of the Society for Psychical Research, in 1898 President of the British Association for the Advancement of Science, from 1913 to 1915 President of the Royal Society itself. The mediumistic investigations did not destroy him professionally – but for a time they cost him ridicule and distancing.
Florence Cook and "Katie King" – the difficult case
In 1874 Crookes investigated a second, much more contested medium: the then 17-year-old Florence Cook, who allegedly produced in trance the materialisation of a whole bodily figure called "Katie King". Crookes held sittings in his own house over several weeks, photographed "Katie King" and described her as a person distinguishable from Cook – different height, different face.
This case is methodologically substantially more problematic than the Home experiments. Florence Cook was caught cheating in 1880 by the sceptic George Sitwell; in one sitting she herself was the "spirit". The Crookes photographs of "Katie King" cannot be unambiguously identified. Later critical historians (Trevor Hall, 1962/1984) have even alleged a personal relationship between Crookes and Cook – this thesis is, however, weakly supported by sources and contested in modern scholarship.
For an honest piece the correct line is: the Home investigations are methodologically solid and stand to this day. The Cook investigations are problematic, but Crookes nevertheless believed in them. Both cases belong to the overall picture – but they do not carry the same evidential weight.
Later recognition and his quiet persistence
What is remarkable: Crookes never retracted his findings. Not in his presidential address to the British Association in 1898, not as RS President in 1913. In 1889, almost 20 years after the first Home sittings, he published in the Proceedings of the Society for Psychical Research a detailed retrospective (Notes of Séances with D. D. Home) in which he restated the experiments – and held to his conclusions. In his inaugural address to the SPR in 1896/97 he repeated that his original observations had been factually correct.
The fact that the establishment nevertheless elected him president of its most important society says something about Victorian scientific culture: it considered his position to be wrong, but considered it to be serious. This tolerance has been largely lost in the 20th century – a historical argument for our piece on Mediumship and Power.
Why Crookes still matters today
- Maximum scientific authority. Discoverer of a chemical element, inventor of the Crookes tube, RS president. Anyone who dismisses Crookes as "credulous" has to explain why the Royal Society elected him as its president after he had published his mediumistic findings – not in spite of, but in parallel with them.
- Methodological pioneering work. What Rhine and PEAR later perfected, Crookes invented in his private laboratory: measuring instead of just observing. Self-built apparatus, protocols, multiple witnesses, photographic documentation.
- "Psychic Force" as forerunner of later hypotheses. The attempt to think mediumistic phenomena as an unknown physical force runs through Pierre Curie, Einstein and Pauli into today's quantum-consciousness debates.
- Steadfastness. Crookes did not recant under intense pressure. In today's scientific culture, in which reputational risks quickly silence researchers, this is itself a historically instructive point.
Crookes belongs in the historical line we are tracing on this site: Kepler, Jung, Pauli, Einstein, the Curies, Rhine, PEAR. He is the earliest in this row – and the one who first built the methodological bridge between Victorian salon Spiritualism and modern experimental research.
Sources
- William Crookes: Spiritualism Viewed by the Light of Modern Science. Quarterly Journal of Science, July 1870.
- William Crookes: Experimental Investigation of a New Force. Quarterly Journal of Science, July 1871.
- William Crookes: Researches in the Phenomena of Spiritualism. Burns, London 1874 (collected edition of the QJS essays).
- William Crookes: Notes of Séances with D. D. Home. Proceedings of the Society for Psychical Research, Vol. 6, London 1889.
- E. E. Fournier d'Albe: The Life of Sir William Crookes. T. Fisher Unwin, London 1923 (the authorised biography shortly after Crookes's death).
- William H. Brock: William Crookes (1832–1919) and the Commercialization of Science. Ashgate, Aldershot 2008 (modern academic biography).
- Trevor H. Hall: The Medium and the Scientist. The Story of Florence Cook and William Crookes. Prometheus, Buffalo 1984 (the critical counter-position on the Cook case – methodologically itself disputed).