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.
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.