RAPS
I will not stop to consider movements with contact. From a physical
point of view they have no serious signification whatever. They are
so easily explained by the combined, unconscious, muscular movements
of the experimenters, that it is really not worth while stopping to
examine them. The messages obtained by their intermedium may present
an internal or clinical interest, but in that case they belong to the
category of intellectual phenomena, properly so-called.
The first physical phenomena, which deserves attention, is that of
‘raps.’ It is generally the one most frequently obtained. We must,
however, point out that the faculties of mediums are not identical:
some produce chiefly physical, others chiefly intellectual phenomena.
The former also manifest diverse qualities: some of them obtain raps,
others movements, others luminous phenomena. Still in a general way
‘raps’ have seemed to me to be one of the simplest phenomena of a
material order.
If we work with a physical medium of even only average force, raps will
be heard after the third or fourth seance. They will be heard much
sooner if we have a powerful medium.
As a rule, raps seem to resound on the top of the table; but it is not
always so. They are frequently heard on the ground, on the sitters, or
on the furniture, walls, or ceiling. The raps I have heard—of course
I am speaking only of genuine raps—have resounded near the medium,
as a rule, either on the table, floor, walls, or furniture in close
proximity to him.
The simplest way to obtain raps is to proceed as I have directed in
section ii. chapter 1. The experimenters, seated around a table, lay
their hands upon it palm downwards, with outstretched fingers. This
method is not, however, to be strongly recommended, for raps are easily
imitated: and we must never lose sight of that fact when appreciating
an experiment; further on, I will enumerate the usual fraudulent
processes. Still, even when the hands are resting upon the table, raps
can be obtained of sufficient sonority to exclude the hypothesis of
fraud, if not absolutely, at least with much probability.
I have received raps in full light. I have received them so frequently
in vivid light, that sometimes I cannot help wondering, whether
darkness facilitates their production to the same extent as it may
other phenomena. It is, however, allowable to suppose, that the
energy which produces them prefers accumulating force in spots that
are sheltered from strong light, _e.g._ under the table, or under the
floor, or in shaded corners of the room. What makes me suppose so is
this, I have frequently noticed that the raps burst forth under the
medium’s hand, when they appeared to be produced on the top of the
table.
Contact of the hands is unnecessary when sitting for raps. I have
procured them quite easily, with several mediums, without such contact.
When we have succeeded in obtaining raps with contact, one of the best
ways of obtaining them without contact is to let the hands rest for
a certain time on the table, then to raise them _very slowly_, palms
downwards, and the fingers loosely extended. Under such conditions,
it seldom happens that raps do not continue to be heard for at least
a short time. I need not say that experimenters should not only avoid
contact of their hands with the table, but even of any part of their
body or clothing. The contact of clothing with the table is sufficient
to produce raps, which have nothing of a supernormal nature. We must be
careful, therefore, that ladies’ dresses especially do not come into
contact with the table; in taking these necessary precautions, raps can
be obtained under most satisfactory and convincing conditions.
With certain mediums the energy liberated is great enough to act at
a distance. I once heard raps upon a table which was nearly six feet
away from the medium. On that occasion we had had a very short seance,
and had left the table. I was seated in an armchair, the medium was
standing by, talking to me, when a shower of raps suddenly resounded
upon the table we had just left. The experimenters are all personally
known to me, and I am persuaded that they are above suspicion;
but this circumstance is quite insufficient in itself to entail a
favourable conclusion of the phenomenon, for I cannot too strongly
put experimenters on their guard against blindly confiding in their
neighbours. Serious experimenters should exclude all susceptibility
amongst themselves, and agree beforehand that reciprocal verification
and control will be freely exercised without any one taking offence.
In the case I am speaking of, the table on which the raps were heard
was about six feet away from the medium and myself; it was daylight,
towards five o’clock on a summer’s afternoon; the table had never been
touched by the medium or the experimenters before the seance; the raps
were loud, and were heard for several minutes.
I have had several opportunities of observing facts of this kind. Once,
when travelling, I came across a medium among my fellow-travellers.
He has not given me permission to name him, but I may say he is an
honourable, highly-educated gentleman, occupying an official position.
He had no suspicion of his latent faculties before experimenting with
me. I obtained with him loud raps in buffets and restaurants. It would
suffice to observe these raps produced under the conditions this medium
offered me, to be convinced of their genuineness. The unusual noise
attracted the attention of persons present and greatly embarrassed us:
the result surpassed our expectations, for the more we were confused by
the noise of our raps, the louder they became; it was as though some
one of a teasing turn of mind was amusing himself at our expense.
I have also heard, when in company with a medium, some very fine raps
given on the floor in museums before the works of old masters, and
especially before religious pictures. I particularly remember the
intensity of certain raps I once heard when standing before a painting
representing the burial of Christ,—the work of a celebrated artist.
I also heard some fine raps in a house which is celebrated as having
been the last home of a famous writer; in the room in which he died,
the raps were so loud as to attract the suspicious attention of the
guardian.
I have also heard formidable raps with the two young girls, fourteen
and fifteen years of age, who were called the Agen mediums. I observed
these mediums at their own home, and I also had them twice at Bordeaux,
when on each occasion they remained for nearly a month. The raps
produced by them are interesting, but they do not seem to me to be
demonstrative. One of these girls obtained raps on the floor under her
feet; I verified the apparent immobility of the foot while the raps
were being produced. When the two girls were in bed, loud raps were
heard near their feet, seemingly given on the wood of their bed. We
were able to observe the apparent immobility of the children. Raps
were also given on the blankets; we could feel the vibrations when
laying our hands on the blankets; the raps appeared to be produced
under our hands. I have heard diverse noises with these children in
obscurity, but I draw no conclusion therefrom. I found out that they
were not always sincere, and that they had a tendency to take advantage
of the confidence and friendliness of the people, with whom they were
staying. They have simulated some of their phenomena, especially raps
in the ceiling. I have never been able to persuade these young girls to
experiment at a table with sufficient conditions of light. They were
accustomed to go to bed in order to procure their raps. It is true I
have heard these raps in daylight, but I consider other conditions
were unsatisfactory on these occasions. I regretted exceedingly that
these mediums showed so little good-will, for even putting aside the
greater part of the suspicious phenomena they produced, there were
still some which seemed to be worthy of further examination.
I have touched upon my observation of these children because it is
instructive, although it may be negative from my point of view. It
shows the inconveniences of a bad method of development. I have noticed
that psychical phenomena has a great tendency to repeat itself, to
follow a certain routine: they tend to turn round the same axis. The
children of whom I have just spoken had been allowed to acquire the
habit of going to bed, in order to obtain the sonorous phenomena they
appeared to produce. Therefore they were able to obtain them only under
those conditions. They have never given me a ‘rap’ by means of a table,
and yet, I am inclined to think that they, or at least that one of
them, had the constitution necessary for the emission of psychic force.
My failure with the Agen mediums was not altogether devoid of interest,
for I gained experience, and experience is only acquired with time,
patience, and multiplicity of observations. It is useful to be able to
compare good, doubtful, and bad seances.
Among my most doubtful experiences, whose recital may be as instructive
as the foregoing, I will choose, for brief discussion, a recent series
of seances which I held at Bordeaux. Some of the phenomena I observed
seem to me difficult to explain by fraud, especially lights which
floated about the seance-room; but the greater part of the motor
phenomena was simulated. The personification had the habit of demanding
total darkness, and as I was chiefly interested in luminous phenomena,
I saw no inconvenience in putting out the lights. The personification,
which made this request, was probably the personal consciousness of
one of the sitters. As soon as the lights were extinguished, the raps
became noticeably louder. Many of them were certainly the work of two
of our number—I have not been able to analyse the mental state of
these two young men: one of them, who is neurasthenic, acted perhaps
unconsciously. Nevertheless, though I observed the whims of these two
men with interest and attention, I noticed, at the same time, that
raps were forthcoming in _total obscurity_ when I made imperceptible
movements, _e.g._ when I gently blew on the table, or when I pressed
the hand of one of my neighbours whose sincerity I could vouch for.
There was always this synchronism, which I have already pointed out,
between the muscular movement and the rap. Without being able to
affirm it absolutely, I think I may say that my co-experimenters were
not aware of the slight movements I made with my feet, hand, finger,
or breath. In these sittings, otherwise bearing a most suspicious
character, there was, therefore, a residue of facts worthy of attentive
analysis. I was unable to make this analysis, having shortly afterwards
ceased to experiment with the group, which these young men frequented.
In some respects I am sorry for it, as the observation of this parcel
of truth, and even of the two fraudulent experimenters themselves, was
interesting from various points of view.
I will now reconsider the experiments I first touched upon—viz.
those conducted in full light—the only ones upon which I establish my
opinion. I have indicated as fully as possible the conditions under
which I have been able to observe raps. The raps most commonly heard
are those given with contact on the table or floor, and then those
which are given at some distance from the experimenters.
Sometimes, but more rarely, I have heard them on cloth, on the medium’s
or sitters’ garments, etc. I have heard them on pieces of paper placed
on the seance table, on books, on the walls, on tambourines, on small
wooden articles, and particularly on a planchette which was used
for automatic writing. I have also observed very curious raps with
a writing-medium:—when he wrote automatically, raps resounded with
extreme rapidity at the end of his pencil. I can affirm that the pencil
did not strike the table, for several times I very carefully put my
hand on the opposite end of the pencil, and I was then able to verify
that the sound was produced at the point of the pencil, the pencil
remaining all the time, steadily and firmly, on the paper—the raps
resounded on the wood of the table, and not on the paper. In this case,
of course, the medium held the pencil in his hand.
Consequently, raps may be given upon various articles, with or without
contact, and even at a certain distance from the medium. I have
observed some which burst forth as far as nine feet away from the
medium. I have not obtained any at a greater distance than nine feet,
and it is not often I have been able to observe them at that distance.
One of the most curious cases I have observed is the following:—I was
experimenting in a room where there was a screen. The table was about
nine feet away from this article. Very clear, distinct raps resounded
on the floor behind the screen. It was broad daylight, but the raps
were given on the shaded side of the screen.
I have frequently heard raps in the seance-cabinet, the medium seated
in front of the curtains as indicated in section ii. chapter 1. Thus
placed, raps are easily obtained behind the medium: they may be given
on the floor, the wall, or on the articles placed in the cabinet. They
are also frequently given outside the curtains, on the medium’s chair,
or on the floor under him. When raps are obtained, it is very easy to
study them by varying, in many satisfactory ways, the conditions of the
experiment. This is one of the phenomena whose reality has been the
most clearly demonstrated to me.
The variety of form the raps may take is not less than the diversity
of objects upon which they may be given, or the places in which they
may be heard. The sound of the usual rap, on a table, reminds you of
the tonality of an electric spark, while of course there are many
variations.
In the first place, we must note that the tonality of raps differs
according to the object upon which they resound. It is easy to
recognise by the sound if the raps are given on wood, paper, or cloth.
This is an interesting demonstration, because it indicates that
the sound is produced by the vibrations of the material substance.
The material molecules of the object struck are therefore put into
movement; they are not, however, always disturbed in the same way,
for the tonality of the raps given on the same object is susceptible
of great variety. The raps, instead of being sharp and short, may be
dull and resemble the muffled sound of impact with some soft body: they
may resemble the slight noises made by a mouse, a fret-saw, or the
scratching of a finger-nail on wood or cloth: they may affect the most
diverse modalities. Their rhythm is as varied as their tonality.
One of the most curious facts revealed by the observation of raps, is
their relation with what I call the personification. Each personified
individuality manifests its presence by special raps. In a series of
experiments which have now lasted for more than two years, I have had
frequent opportunity of studying raps personifying diverse entities.
One of these entities called itself ‘John,’ Eusapia’s control, who has
retained a friendly feeling for me, it appears, ever since my first
experiments with the Neapolitan medium. ‘John’ manifests by short,
sharp raps, so very like the manipulation of the Morse telegraph,
that my co-experimenters and I wondered whether we were not actually
listening to the usual Morse signals. Unfortunately none of us knew
how to recognise letters by rhythm as exercised telegraphists can. A
group, of four individualities, who call themselves the ‘Fairies,’
manifest their presence by raps resembling high, clear notes. These
personifications are particularly interesting, and, further on, I will
have occasion of relating how one of them showed herself to me. The
four fairies are fond of mingling in the conversation, approving or
disapproving of the ideas expressed by the experimenters. They appear
to take considerable interest in the experiments, and I have often
noticed that it sufficed—when the raps delayed in making themselves
heard—to turn the conversation upon psychical phenomena, their
probable explanation, their conditions of realisation, etc., in order
to receive approving or disapproving raps at once. Sometimes the raps
imitate a burst of laughter—this coincides either with an amusing story
related by one of the sitters, or with some mild teasing. Another
entity personifies a man for whom I had the deepest affection: these
raps are graver in character. This personality seems to have the
clairvoyant perspicacity and the kindheartedness of the man I knew.
His intervention manifested itself under very curious circumstances,
but of too private a nature to be made public. I will cite another
personification of more recent appearance. It gives itself out to be
the astronomer, Chappe d’Auteroche, and has related most accurately the
details of his life and death in California. As a biographical notice
concerning this learned man appears in several dictionaries, notably
in Larousse, it is impossible to affirm that the irruption of this
personification is supernormal. The raps which announce his presence
are dull-sounding, and are given with a certain amount of force. In
conclusion, light precipitated raps, weak but abundant, are the signals
of certain personifications which we might call mar-joys—troublesome
guests, whose unwelcome intervention spoils the experience.
Let it not be forgotten, that if I point out the connection existing
between the personifications and the raps, it does not follow that I
accept the reality of those personifications. I am making a statement,
and I fill in all the details, so that experimenters, tempted to resume
my observations, may know exactly what I have observed. So far, the
personifications have not convinced me of their identity. It is true I
act somewhat indifferently the rôle of listener to their fatiguing and
rambling conversations, and that I do all I can to bring them back to
material phenomena, so much more important to me in that they are so
much easier to verify. Were I, however, not to point out the rôle which
the raps play in relation to the personification, I would be omitting
one of their most significant features, and would not be giving their
exact physiognomy.
They manifest themselves, then, as the expression of a will and
activity distinct from those of the observers. Such is the _appearance_
of the phenomenon. A curious fact is the result—not only do the raps
reveal themselves as the productions of intelligent action, they also
manifest intelligence in response to any particular rhythm or code
which might be demanded.
Often the different raps reply to one another; and one of the most
interesting experiences one can have is to hear these raps clear and
resonant, or soft and muffled, sounding simultaneously on the floor,
table, furniture, etc.
I have had exceptionally good opportunities of studying very closely
this curious phenomenon of raps, and I think I have arrived at some
conclusions. The first and most certain is their undoubtedly close
connection with the muscular movements of the sitters. I may sum up my
observations on this point in the three following propositions:—
1. All muscular movements, however slight, are generally
followed by a rap.
2. The intensity of the raps does not strike me as being in
proportion with the movement made.
3. The intensity of the raps does not seem to me to vary
proportionately according to their distance from the medium.
The following are the facts upon which I build my conclusions:—
I. I have frequently found that when the raps were feeble or
interspersed, an excellent way of producing them was to form a chain
of the sitters’ hands round the table. One of the sitters, without
breaking the chain—which he avoids doing by taking in the same hand
his neighbours’ right and left hands—makes, with his freed hand,
circular sweeps or passes a little distance above the circle formed by
the sitters’ outstretched hands. Having done this, the experimenter
draws his hand towards the centre of the circle to a variable height,
and makes a slight, downward movement with his hand; then he abruptly
arrests the movement at about five or six inches away from the table,
when a rap invariably follows, corresponding with the sudden cessation
of the movement. It is exceptional when this process does not give
a rap as soon as there is a medium in the circle who is capable, in
however feeble a degree, of producing raps.
The same experiment can be made without touching the table, _i.e._ by
forming the chain above the table. One of the sitters then experiments
as in the preceding case.
This is not the only observation I have made. I have noticed that with
mediums of decided power, it was unnecessary to adopt any special
method for the production of raps, as they were forthcoming as soon
as any sort of movement with hands or feet was executed. With strong
mediums, it often suffices to move the hand above the table, to shake
the fingers, to gently press the foot upon the ground, in order to
determine the production of a rap.
Needless to say with some mediums raps are forthcoming without the
execution of any movement whatsoever: with patience nearly all physical
mediums can obtain raps without movement. But it seems as though the
execution of a movement acted in the nature of a determining cause: the
accumulated energy then receives a sort of stimulus, the equilibrium
is disturbed by the addition of the excess energy unemployed in the
movement, and a kind of explosive discharge of neuric force occurs,
causing the phenomenon of raps. This is, however, only a working
hypothesis.
The synchronism between the raps and the movements made by the sitters
is very interesting, as it reveals the connection which exists between
the organism of the experimenters and the phenomena observed. Richet
has already pointed this out. Eusapia Paladino, unconsciously perhaps,
employs a process analogous to that which I described a little further
back. This synchronism may give, as it has given, equivocal phenomena,
and may also give rise to many false accusations of fraud. This is
perhaps how Dr. Hodgson comes to attribute certain raps produced by
Eusapia Paladino at Cambridge, to the latter striking the table with
her head. Of course, I am unable to affirm the reality of the raps
heard at Cambridge, seeing I was not present at the sitting of the
Sidgwick group. I can but say, that the reading of the few extracts of
the _procès verbaux_ of these seances—most incomplete extracts—does
not by any means indicate, whether the movement of the Italian medium’s
head was the fraudulent physical cause of the rap, or whether this
movement was but a synchronous phenomenon.
I cannot help thinking that the Cambridge experimenters were either
ill-guided, or ill-favoured, for I have obtained raps with Eusapia
Paladino in full light, I have obtained them with many other mediums,
and it is a minimum phenomenon which they _could_ have, and _ought_ to
have obtained, had they experimented in a proper manner.
I will discuss these seances more fully further on.[4] Therefore,
even in the appreciation of fraud, we must not forget to take into
consideration the curious synchronism I am pointing out.
[4] See Appendix B.
There is another useful observation to make known: namely that raps
produced by synchronous movements can be produced by the sitters
themselves. In many cases, I have seen experimenters, non-mediums,
obtain louder raps than the medium; the presence of a medium, however,
is necessary, for, the persons of whom I speak obtain no raps whatever
when alone. Here is a subject for study which has not yet been touched
upon.
Sometimes, in order to obtain raps, it suffices to touch the medium, or
to make a slight movement with the hand above the table, or simply to
place the palm of the hand gently on the table; this is an excellent
way to obtain clear, decided phenomena. The table must be moved away
from the medium in such a way that contact is impossible. The observer
puts himself beside the medium, takes both his hands in one of his own,
and moves the other slowly over the table, or even keeps it quite still
above the table. Nothing is more demonstrative than this experiment.
Let us remember I am speaking of experiments made in broad daylight.
II. Secondly, I have verified that the intensity of the raps is
not in proportion with the synchronous movement. I am unable to
affirm the accuracy of this statement with the same confidence as
with the preceding one; but I have observed the fact in a great many
circumstances. Thus, _e.g._ a very slight movement of the finger will
sometimes determine a rap, quite as loud as the rap determined by the
abrupt lowering of the whole arm.
Again, a simple muscular contraction also will bring about the
realisation of the phenomenon, without the execution of any apparent
movement.
This observation is of special interest, if I am not mistaken, for it
tends to make one suppose that the energy which serves to produce the
raps is independent of the movement executed in space, but is connected
with the cause of that movement, _i.e._ with the nervous influx. It
would be well if experimenters, more competent than I am in physiology,
were to study these observations carefully; I sincerely hope this will
be done some day. Richet might well undertake these researches, for no
one is more competent than he is to analyse the facts I am pointing out.
I think there is a close connection between psychical phenomena and the
nervous system. What I have just said about the production of raps by
the simple contraction of a muscle under a voluntary nervous influx is
one of the reasons upon which I base my hypothesis.
There are others. I have often questioned mediums about their
sensations when the raps were being produced. They all acknowledged to
a feeling of fatigue—of depletion—after a good seance. This feeling
is perceptible even to observers themselves. I have tried to analyse
my own sensations when the raps are heard; I have not arrived at any
positive result. I cannot say I have any decided physical sensation;
but my negative observation is only of interest, if compared with the
different observations I made, in connection with the production of
movements without contact.
One of the mediums, with whom some of my best and clearest raps were
obtained, tells me he experiences a feeling akin to cramp in the
epigastric region when the raps are particularly loud. This medium is
a clever and highly-educated man, one quite capable of analysing his
own symptoms. It seems to him as though something emanated from his
epigastrum.
III. Regarding my third proposition—the intensity of the raps is not
appreciably affected by distance—I have found that raps could occur
as far as three yards away from the medium. The raps given at this
distance were as loud and clear as those given close to the medium.
This fact would at first seem to imply a difference between the action
of psychic force and that of gravitation, light, heat or electricity,
all of which act with an energy in inverse proportion to the square of
distances. However, such a conclusion would be premature, for secondary
centres of accumulation of energy may be formed at a distance from the
medium. The term ‘accumulation of energy’ is very vague and may be
incorrect, but I dare not give a more precise one, and confine myself
to simply stating, that the existence of such centres of accumulation
and emission seems indicated, by the manner in which the phenomena are
obtained.
I have never verified any serious physical effects at a greater
distance than that of ten feet. I will add that if the phenomena are
not more intense, they are at least more frequent in the immediate
neighbourhood of the medium.
Such are the observations I have been able to make. It may quite
naturally occur to my readers to think I have been the victim of
illusion or fraud. This is not the case, however.
There is no illusion, simply because nothing permits me to suppose I
am the victim of illusion. This assertion is insufficient, I admit:
we are bad judges of ourselves. And now I ought to say, that if up to
the present I have always clearly distinguished between real facts and
subjective impressions, I present, nevertheless, two phenomena which
may render my testimony suspect. The first is hypnagogic hallucination,
the second coloured audition. The latter is not very decided; sound
simply awakens in me the idea of colour, not the visual sensation
of colour. My chromo-phonetic scale is _A_, white; _I_, black; _É_,
grey; _E_, blue; _on_, green; _er_, _air_, _œil_, orange, etc.[5] This
phenomenon was rather marked when I was a child; but, I repeat, the
reading of vowels or diphthongs, or the audition of sounds has never
awakened a complete sensation of colour; the idea only was evoked.
[5] This scale is applicable to the French pronunciation of the
vowels in question.
On the contrary, hypnagogic illusion is, with me, a decided phenomenon.
The illusion is exclusively visual. I have carefully observed this
interesting faculty on myself; it appears to me to have its origin in
dream. It is a dream begun before sleep has taken complete possession
of one. The hallucination disappears as soon as somnolence ceases.
It is with extreme difficulty that I am able to retain—even for a
second—a hypnagogic picture, when I regain complete consciousness; in
spite of all my efforts, the picture fades away or changes form as
soon as I fix my attention upon it. I have seldom been able to maintain
the illusory impression.
We must not conclude, that I am incompetent to distinguish a real
phenomenon from a false one, because of the existence in myself of
these two subjective phenomena. I have indicated the results of my
self-observation in order to be thoroughly sincere and complete, for
I have the keenest desire to be an accurate witness. I do not think,
however, that the observations I have been able to make upon myself are
really of a nature to cast suspicion upon my faculties of observation.
Quite the contrary, I should say; because my personal experience
enables me to recognise hypnagogic hallucinations, and, further on, I
will point out some phenomena which seem to me to be closely connected
with these hallucinations; but as for raps, they have quite a different
character, and their objectivity appears quite certain to me.
I will add that every one present can and does hear them. Let me recall
to mind what I said about the raps I heard in railway refreshment
rooms, restaurants, and other public places. All who were in the same
room showed, by their demeanour, that they too heard the raps. This
circumstance suffices to exclude the hypothesis of hallucination.
I propose registering these raps in a phonograph; this will be the
_experimentum crucis_ as far as their objectivity is concerned.
I have no manner of doubt whatsoever upon the authenticity of raps,
a phenomenon I have heard so frequently, and under such diverse and
excellent conditions. I have also taken care to study the different
ways of simulating raps,—and these are indeed manifold.
The simplest and most perfect method is to gently glide—an
imperceptible movement—the finger-tips along the table. The results
are better when the finger is dry, when the natural grease has been
previously removed by turpentine or benzine: resin is good, but leaves
traces. Under these conditions, slight but clear raps may be obtained.
The movement of the finger is so slow, that, unless forewarned, no one
can discover it; but, with attentive observation, a slight vibration of
the finger may be perceived when the raps burst forth. They can also be
simulated with the finger-nails, but this process is easy to unmask.
The trickster finds greater security in darkness, where he has
resources other than those just mentioned. In obscurity he can easily
imitate the raps which resound on the floor; _e.g._ he can produce dull
raps by skilfully striking his foot against the legs of the table or on
the floor; he can simulate the sharp, quick raps by allowing his boot
to glide slowly along the feet of the table or chair.
Raps are also very easily simulated by a gentle rubbing of clothing or
linen, especially shirt-cuffs. We should beware of this, for raps can
thus be produced by slow unconscious movements, and the good faith of
the experimenters may be involuntarily taken by surprise.
There is yet another way of obtaining fraudulent raps; this is by
leaning more or less heavily on the table. When the top of the table is
thin, or when the table is badly put together, or the parts have too
much play, the variations of the pressure of the hand determine noises
which greatly resemble raps.
Lastly, I have sometimes observed raps produced in a way which should
be made known. Some people, by leaning the foot in a certain way, and
by contracting the muscles of the leg, can imitate raps on the ground.
This fact has been indicated especially in connection with the sinews
of the musculus peronaeus longus. I observed a medical student, an
incorrigible cheat and neurotic, who obtained sounds very similar to
authentic raps by leaning his elbow on the table, and making certain
movements with his shoulder. There are also some people who can make
their joints crack at will.
But force of habit soon teaches how to ferret out fraud, when working
in daylight or with good artificial light. Besides, the tonality
of authentic raps is characteristic, and the method of simulation
indicated at the beginning of these remarks, _i.e._ finger-gliding, is
the only one able to reproduce some of the raps with even a fair amount
of exactness.
It does not seem to me to be possible to simulate raps on the table,
when they are produced without contact. It is easy to localise
them, and auscultation of the table enables us even to perceive the
vibrations of the wood. Precautions, easily taken, enable us to
make sure of the absence of contact and communication between the
experimenters and the table.
To sum up, I am certain—as far as it is reasonably possible to be
certain of anything in such a matter—that knockings of variable rhythm
and tonality are heard in the presence of certain persons—knockings or
‘raps’ which cannot be explained by any known process. They are heard
at diverse distances; they often seem to obey the expressed wishes of
the sitters, and to manifest a certain independent intelligence. On the
other hand, their production appears to be intimately connected with
the nerve-energy of the medium and the sitters.
I think I am able to express the foregoing conclusions with certainty
and confidence.