The popular name of _spiritual rapping_ gives a very poor idea of this class of phenomena. On different occasions during his experiments, Mr. Crookes heard blows of a delicate variety, such as might be produced by the point of a needle; a cascade of sounds, as acute as those coming from an induction coil in full activity; sharp blows or detonations in the air; acute notes of a metallic variety; rasping sounds similar to that heard from a machine with rubbing action; noises like scratching; twittering chirps like a bird, etc. “I have observed these noises,” says Crookes, “with the majority of mediums, each of whom has a special peculiarity. They were more varied with Mr. Home; but, for force and certainty of result, I have never met a medium who approached Kate Fox. For several months I experimented, it may be said, in an unlimited manner, and verified the different manifestations induced by the presence of this lady, and I especially examined the phenomenon relative to these noises. “With mediums, it is necessary in general that they be methodically seated for the _seance_ before noises are heard, but with Miss Kate Fox it was sufficient to merely place her hand on any object, no matter what, and violent blows were heard, like a triple sound of beating, and sometimes so loud as to be heard at different pieces of furniture in the room. “In this manner, I have heard these noises on a living tree, on a fragment of glass, on a membrane extended in a frame—for instance, a tambourine—on the top of a cab, and on the edge of the parquet railing in the theatre. “However, effective contact is not always necessary. I have heard the noise sound inside walls, when the hands and feet of the medium were tightly held; when Miss Fox was seated in a chair; when she was suspended above the platform; finally, when she had fallen on a sofa in a dead faint. “I have heard these same noises on the harmonica; I have felt them on my shoulder and under my hands; I have heard them on a leaf of paper held between the fingers by the aid of a wire passed through one corner. “With a perfect knowledge of the numerous theories advanced, in America principally, to explain these knocks or spirit rapping, I have verified them by all methods I could imagine, so that I have acquired a positive conviction as their objective reality, and the absolute certainty that it was impossible to produce these sounds by artifice or some mechanical means. “An important question is here asked that deserves attention, _i.e._ ‘_are these noises governed by an intelligence?_’[84] “From the commencement of my investigations, I have recognized the fact that the power which produced the phenomena, was not simply a fluid force, but that _it is associated with an intelligence, or follows its directions_.”