V.A.[219] The principal inorganic objects alleged to have elicited novel sensations are running water, metals, crystals and magnets;—including under this last heading the magnetism of the earth, as claimed to be felt differently by sleepers according as they lie in the north-south or in the east-west positions.
(1) The faculty of finding running water has the interest of being the first subliminal faculty which has been so habitually utilised for public ends as to form for its possessors a recognised and lucrative occupation.
An exhaustive and impartial survey of the existing evidence for the faculty of "dowsing" is given in Professor W. F. Barrett's two articles "On the so-called Divining Rod" in the Proceedings S.P.R., vol. xiii. pp. 2-282, and vol. xv. pp. 130-383.
From this it seems clear that this power of discovery is genuine, and is not dependent on the dowser's conscious knowledge or observation. It forms a subliminal uprush; but whether it is akin to genius, as being a subconscious manipulation of facts accessible through normal sensory channels, or to heteræsthesia (as resting on a specific sensibility to the proximity of running water), is a question which will be variously decided in each special case. The dowser, I should add, is not hypnotised before he finds the water. But (as Professor Barrett has shown) he is often thrown, presumably by self-suggestion, into a state much resembling light hypnotic trance. The perceptivity (we may say) of central organs, in an unfamiliar direction, is stimulated by concentrated attention, involving a certain disturbance or abeyance of perceptivity in other directions.
(2) I next take the case of metallæsthesia,—that alleged reaction to special metals which has often been asserted both in hypnotic and in hysterical cases. As a definite instance I will take the statement made by certain physicians attending Louis Vivé,[220] that while they supported him during a hysterical attack a gold ring on the finger of one of them touched him for some time and left a red mark, as of a burn, of whose origin the patient knew nothing. It is further alleged—and this is a quite separate point, although often confused with the first—that gold is distinguished by some subjects under conditions where no degree of sensitiveness to weight or temperature could have shown them that gold was near.
Now, as to the first point, e.g. the Louis Vivé incident, I can readily believe that the touch of gold, unknown to the subject's supraliminal consciousness, may produce a redness, subsequent pain, etc. All that is needed for this is a capricious self-suggestion, like any other hysterical idea. This self-suggestion might remain completely unknown to the waking self, which might be puzzled as to the cause of the redness and pain. The second claim, however, involves much more than this. If gold is recognised through a covering, for instance, or heated to the same point as other metals, so that no sensation of weight or temperature can help observation, this might possibly be by virtue of some sensibility more resembling the attraction of low organisms to specific substances whose chemical action on them we cannot determine, or to particular rays in the spectrum. I am not convinced that this has yet been proved; but I should not regard it as a priori impossible.
Medicamentous substances have also been claimed by many different hypnotists as exerting from a little distance, or when in sealed tubes, specific influences on patients. The phenomenon is of the same nature as the alleged specific influences of metals,—all being very possibly explicable as the mere freak of self-suggestion.
(3) Considering in the next place the alleged sensibility of certain persons to crystals and magnets,—known to be absolutely inert in relation to ordinary men,—we should note the alleged connection between the perception of magnets and that of running water.
Some experiments intended to test the reality of the "magnetic sense," and especially of the so-called "magnetic light"—luminous appearances described by Baron Reichenbach as being seen by his sensitives in the neighbourhood of magnets—were carried out by a Committee of the S.P.R., in 1883. After careful and repeated trials with forty-five "subjects" of both sexes and of ages between sixteen and sixty, only three of these professed to see luminous appearances.
The value of these experiments as evidence of a magnetic sense of course depends primarily on whether the subjects had any means, direct or indirect, of knowing when the current was made or broken. The precautions taken to avoid this and the other conditions of the experiments are described in detail in the report of them in the Proceedings S.P.R., vol. i. pp. 230-37. See also a further note by the Chairman of the Committee, Professor W. F. Barrett, vol. ii. pp. 56-60.