That the human body should be home to a physical soul which survived death was at one time rarely questioned. Then came the advent of scientific disciplines such as anatomy, chemistry and physics, whose probing and measuring raised awkward questions about where in the body a soul could live and what physical form it could take. With no medical proof being forthcoming, in 1854 the German anatomist Rudolph Wagner suggested that there must be a “special soul substance” in the body, evidence of which should be sought out by experimentation. Wagner was much ridiculed for his beliefs, and some years later his rival Ernst Haeckel mocked that at the moment of death it might be possible to liquefy the soul by freezing it and then “exhibit it in a bottle as immortal fluid”.
The nature of a human soul was a much-discussed topic within Victorian psychical research communities, many of whose members were also eminent scientists. Different philosophical conclusions were reached, but none was based on empirical evidence, it being deemed too difficult to measure any of the soul’s presumed physical properties. However, not everyone was prepared to accept this, and in the winter of 1896 Dr Duncan MacDougall, a Massachusetts-based surgeon, came up with a novel idea. “Why not,” he asked, “weigh on accurate scales a man at the very moment of death?”
MacDougall was a member of the American Society of Psychical Research and had a fascination with the idea that the human personality could survive death. Like others in his profession, he knew of no physical location within the body where the soul could be found but believed that it was “unthinkable that personality and continual personal identity should exist… and not occupy space”. He termed the hypothetical space occupied by the human personality the “soul substance” and argued that, because it did not leave the body until the moment of physical death, it must be held in place by an organic link. This, suggested MacDougall, meant that the soul substance probably had some form of mass and was “therefore capable of being detected at death by weighing a human being in the act of death”.
SOULS IN THE SCALES
By 1901, MacDougall had adapted a set of industrial beam scales (accurate to within five grams) so that one side held a platform onto which was placed a lightweight hospital bed while the other contained individual weights which could be added or subtracted to measure any change in mass. Once installed in his hospital, the surgeon then approached several terminally ill patients to ask if they would allow themselves to be weighed during the final hours of their life. On 10 April 1901, his chance came, and at 5.30pm a man “of the usual American temperament” and suffering from tuberculosis was placed onto the apparatus. He was attended by at least four people, including MacDougall and Dr John Sproull, a sympathetic colleague. Like many suffering from this disease, the exhausted patient was calm and as he ebbed away, any change to his weight was noted.
Over the course of three hours, there was a small but steady loss of weight, which was put down to loss of water through sweating and respiration. Then, around 9pm, the man’s condition worsened and a few minutes later he died. MacDougall explained what happened next.
“The instant life ceased, the opposite scale pan fell with a suddenness that was astonishing – as if something had been lifted from the body.” MacDougall and his colleagues ascertained the weight loss to be 21 grams.
The immediate and measurable loss of weight at the moment of death excited MacDougall but, as it was the first experiment of its kind to be undertaken, he wanted to explore all potential explanations. The patient was found not to have evacuated his bowels, but he had emptied his bladder – although the urine had soaked into the sheets beneath and had not left the bed. This was not deemed to be sufficient to cause a sudden weight loss and subsequent experiments involving forcibly inhaling and exhaling air could not cause the scales to move in a similar fashion. To MacDougall, the missing 21g at the point of death was inexplicable using any conventional medical knowledge but, as he acknowledged, this was just one patient.
In November, MacDougall was presented with his second patient, also a male suffering from tuberculosis and similarly moribund during his final hours. The measurements were made over a period of four and a quarter hours, after which time the man stopped breathing, although his face continued to twitch for some 15 minutes afterwards.
“Coinciding with the last movement of the facial muscle,” wrote MacDougall, “the beam dropped. The weight loss was found to be half an ounce”. As before, MacDougall tried to account for the weight-loss in conventional terms but concluded that it was inexplicable.
Between January and May 1902, a further four patients consented to die on the beam scales. In two cases, sudden losses of 10 and 14 grams were recorded at death, while one experiment apparently had to be abandoned because “There was a good deal of interference by people opposed to our work.” The other patient recorded no weight-loss, something which MacDougall blamed on his having been on the scales only a short time before death.
MacDougall believed that his results could not be explained by natural means and that the loss of weight was being caused by the “soul substance” exiting the body at the time of death.
Communications with Dr Richard Hodgson, President of the American Society for Psychical Research, convinced MacDougall that he was on track, but he worried that “Other experimenters will discover it to be a mare’s nest.” Subsequently, MacDougall repeated the same experiment using 15 dogs, which were anæsthetised and then killed on a beam scale. (The source of these unfortunate animals is not known, but they were apparently “all healthy”.) Unlike his human subjects, no weight loss was observed. From this MacDougall concluded that weight loss at death was a purely human phenomenon – something that only made sense if humans had a soul substance that other animals lacked.
Since devising the experiment, MacDougall had experienced the continual wrath of his superiors at the hospital (he refers to “foolish misunderstandings” as well as the “interference” mentioned above) and was eventually banned from undertaking any further work. He chose to sit on his results for several years, for reasons unknown, before releasing news of his findings to The New York Times, which ran a lengthy piece on 11 March 1907.
The reaction was predictable, with correspondents divided between sceptics offering rationalist explanations and supporters adding their own theories and anecdotal evidence. Such was the clamour for further detail that MacDougall wrote up his results into a paper simultaneously published in the prodigious scientific journal American Medicine and the Journal of the American Society for Psychical Research. In it he presented his evidence and added a further discussion putting forward the idea that the soul substance was lighter than air. MacDougall wrote in guarded terms, inviting others to repeat his experiment, but his conclusion came down in favour of a soul substance being the cause of the observed weight loss.
The correspondence continued, especially in American Medicine, many of whose readers were disgruntled at the journal for agreeing to publish the results in the first place. The results were never confirmed or explained, but the idea that a doctor had weighed a human soul slipped into collective memory as offering scientific proof of human immortality.
MacDougall’s work later inspired Laura Gilpin’s poem The Weight of a Soul and the 2003 film 21 grams (this being the weight loss experienced by the first patient). MacDougall’s later years saw him move away from psychical research and into poetry: to judge by his published verse, he was probably better suited to the former than the latter. He died in October 1920, aged just 54 years.
Given the philosophical implications of Dr MacDougall’s experiments, it isn’t too surprising that they caused such a stir and that even today they should still be widely talked about. However, his work has never been repeated and its immediate dismissal by the medical community means that little formal attention has been paid to these startling results.
Deducing exactly what went on in MacDougall’s laboratory after more than a century has passed is no easy task, but a possible insight comes from some written correspondence between MacDougall and Richard Hodgson. These letters (which were later published by the American Society of Psychical Research) start in November 1901, after MacDougall’s first experiment, and continue until May 1902, when the entire project was halted. They contain a full description of MacDougall’s methods, results and the circumstances of all six patients which, when compared with his American Medicine paper, offer some clues to the solution of this mystery.
MacDougall’s letters make it plain that, with the exception of the first patient, all the experiments were beset with problems that may be broadly divided into one of two categories. The first problem was in ascertaining the exact time of death, an issue that appears to affect patients two, three and six. MacDougall acknowledged this with the second patient, where the period of uncertainty lasted for 15 minutes, but with patient three it is only in his letters that we learn of “a jarring of the scales” made while trying to determine “whether or not the heart had ceased to beat”. Patient six was excluded for other reasons (see below), but in his letters MacDougall remarks that “I am inclined to believe that he passed away while I was adjusting the beam”, which again suggests uncertainty as to the exact moment of death.
The second issue was a problem relating to the measuring equipment itself, which MacDougall himself cited as a reason for voiding the results of patients four and six. However, with the fifth patient the measured drop in weight at death was later followed by an evident malfunction, as the scales could not afterwards be made to re-balance themselves correctly. In any objective experiment this uncertainty would have voided the result, but at no point does MacDougall question the reliability of his set-up. Thus, of the six patients, just one (the first) appears to have been measured without mishap, but repeated troubles with the equipment and with determining the moment of death perhaps casts doubt on even these results. Thus, rather than trying to find a physical cause for the loss of weight at death, it is conceivable that there was no loss of weight at all, or that it might not have coincided with the moment of death. Only a complete retrial with human patients will answer these questions, and that has so far not been forthcoming.
MacDougall’s correspondence reveals a man with an unswerving belief in the existence of a human soul. At every turn he sought to justify his results in these terms, dismissing or ignoring any evidence to the contrary. It is, for example, possible that he ignored the results of the sixth patient because, in his own words, “there was no loss of weight” measured at the time of death. MacDougall explained in a letter that the negative result was probably due to the patient having been on the scales for only a few minutes, which caused him to doubt “whether I had the beam accurately balanced before death”. This seems like an afterthought used to explain an inconvenient result and one wonders what his reaction would have been should the result have been favourable.
To me, it seems that MacDougall’s human experiments were hopelessly beset with technical difficulties that serve to make the results unreliable and meaningless. It is probable that his experiments with dogs were carried out under more controlled conditions as it was possible to induce (and therefore better gauge) the time of death. Also, these experiments were carried out using a different set of scales, sensitive to 1.75 grams (as opposed to 5g with the other equipment), and yet no loss of weight was observed. This was also true for a similar experiment performed in 1915 by H Twining using 30 mice that were killed in a variety of situations while being continually weighed. No weight gain or loss could be detected, and the same was possibly true for a similar mouse experiment mentioned in The New York Times (13 March 1907), although I can find no further details of this. One experiment stands in partial contrast and that is by Lewis Hollander, who observed a variation in weight of between 18 and 780g in the few seconds following the induced death of seven sheep. This weight change was, however, not permanent and could not be measured in either lambs or a goat.
Perhaps the final word should go to psychical researcher Donald Carpenter, who suggests that a new unit be created in order to define the energy require to sustain a human soul. He proposes that the unit be called “The Mac” in honour of the pioneering work of Duncan MacDougall.
PHOTOGRAPHING THE SOUL
The work of Duncan MacDougall may not have set the medical world alight, but it certainly inspired others to conduct their own search for evidence of the human soul. One such episode began in 1910 when Walter Kilner, a medical technician at London’s St Thomas’s Hospital, announced that he had created a special set of glass filters that, with suitable training, would allow people to observe the human aura or Etheric Double, as he termed it.
Kilner’s experiments were published in a book which, in 1911, influenced Patrick O’Donnell, a Chicago “X-ray expert”, to create some Kilner-style glass filters through which he could observe the human aura. With MacDougall’s weight experiments in mind, O’Donnell was given permission by the Mercy Hospital to use his filters to observe a dying man.
“The attending physician announced that the man was dead,” said O’Donnell. “The aura began to spread from the body, and presently disappeared. Further observation of the corpse revealed no sign of the aura.”
O’Donnell sought not to explain his observation in terms of the soul but suggested that: “[I]t is some form of radioactivity made visible by the use of the chemical screen. My experiments, however, seem to prove that it is the animating power, or current of life of human beings.”
Shortly afterwards, it was announced in the press that a race had developed between O’Donnell and Duncan MacDougall as to who could be the first to photograph the human soul, a feat which had thus far eluded Walter Kilner. The New York Times greeted this news with scepticism: “We rely upon Drs O’Donnell and MacDougall for further authentic photographs and weights of the animating power, the etheric projection, the current of life, the last breath, the soul substance or whatever it may be called to make possible [..] a substitute for the customary word-pictures of the sea serpent.”
This article claimed to have interviewed MacDougall, but the surgeon denied this and wrote to the paper, complaining that: “I am not about to conduct experiments for obtaining pictures of the human soul.” He went on to explain that, while the human soul was “substantial and space occupying [..] it could not be made the subject of photography” because its refractive index was identical to that to the “ether of space”.
This angry missive dates from July 1911 and is the last comment I have found by MacDougall on the subject of his earlier research, but it seems to confirm that his opinions on the subject of the soul remained unchanged with time.
New York Times, 11+12+13+14+15 Mar 1907; 16 Oct 1920.
New York Times, 5 Feb, 16+24+25+28 July, 28 Aug 1911.
D Carpenter: Physically Weighing the Soul.
L Hollander: Journal of Scientific Exploration (v.15, pp495–500).
D MacDougall: American Medicine, v.13, pp240–3, 1907.
D MacDougall: “Correspondence”, Journal of the American Society for Psychical Research, v.1, pp264–275, 1907.
M Roach: “A Soul’s Weight”, Lost Magazine, Dec 2005.
H Twining, see H Carrington: Laboratory Investigations into Psychic Phenomena, Rider & Co., 1939.