Except where darkness has been a necessary condition, as with some of the phenomena of luminous appearances, and a few other instances, everything recorded has taken place in the light. In the few cases where the phenomena noted have occurred in darkness I have been very particular to mention the fact. Moreover, some special reason can be shown for the exclusion of light, or the results have been produced under such perfect test conditions that the suppression of one of the senses has not really weakened the evidence.
I have said that darkness is not essential. It is, however, a well-ascertained fact that when the force is weak a bright light exerts an interfering action on some of the phenomena. The power possessed by Mr. Home is sufficiently strong to withstand this antagonistic influence; consequently, he always objects to darkness at his séances. Indeed, except on two occasions, when, for some particular experiments of my own, light was excluded, everything which I have witnessed with him has taken place in the light. I have had many opportunities of testing the action of light on different sources and colors,—such as sunlight, diffused daylight, moonlight, gas, lamp, and candle-light, electric light from a vacuum tube, homogeneous yellow light, etc. The interfering rays appear to be those at the extreme end of the spectrum.
Professor Crookes next proceeds to classify the phenomena observed by him, going from the more simple to the more complex and giving in rapid review under each head, a sketch of some of the facts. In the abridgment of his report which follows I eliminate what has already been fully demonstrated elsewhere in this book.
First class: The movement of Heavy Bodies with Contact, but without Mechanical Exertion.
(This movement has been fully proved in this volume.)
Second class: The Phenomena of Percussive and other Allied Sounds.
An important question here forces itself upon the attention. Are the movements and sounds governed by intelligence? At a very early stage of the inquiry, it was seen that the power producing the phenomena was not merely a blind force, but was associated with or governed by intelligence. Thus the sounds to which I have just alluded will be repeated a definite number of times. They will come loud or faint, and in different places at request; and by a pre-arranged code of signals, questions are answered, and messages given with more or less accuracy.
The intelligence governing the phenomena is sometimes manifestly below that of the medium. It is frequently in direct opposition to the wishes of the medium. When a determination has been expressed to do something which might not be considered quite right, I have known urgent messages given to induce a reconsideration. The intelligence is sometimes of such a character as to lead to the belief that it does not emanate from any person present.
Third class: The Alteration of Weights of Bodies.—(Experiments which have been already described.)
Fourth class: Movements of Heavy Substances when at a distance from the Medium.—The instances in which heavy bodies, such as tables, chairs, sofas, etc., have been moved, when the medium has not been touching them, are very numerous. I will briefly mention a few of the most striking. My own chair has been twisted partly round, whilst my feet were off the floor. A chair was seen by all present to move slowly up to the table from a far corner, when all were watching it. On another occasion an arm-chair moved to where we were sitting, and then moved slowly back again (a distance of about three feet) at my request. On three successive evenings a small table moved slowly across the room, under conditions which I had specially pre-arranged, so as to answer any objection which might be raised to the evidence. I have had several repetitions of the experiment considered by the Committee of the Dialectical Society to be conclusive, viz., the movement of a heavy table, in full light, the chairs turned with their backs to the table, about a foot off, and each person kneeling on his chair, with hands resting over the back of the chair, but not touching the table. On one occasion this took place when I was moving about so as to see how everyone was placed.