These experiments date from the years 1871 to 1873. During the last mentioned year, a new medium, endowed with particularly remarkable powers, appeared in London, namely, Miss Florence Cook, who was born in 1856, and was, therefore, seventeen in 1873. Since the preceding year (1872), she had often seen the apparition by her side of a young girl. This spectral form had taken a liking to her, and told her she was called _Katie King_ in the other world, and had been a lady called Annie Morgan during one of her lives on earth. Some observers told marvellous stories of these apparitions, which they also saw,--among them being William Harrison, Benjamin Coleman, Mr. Luxmore, Dr. Sexton, Dr. Gully, the Prince of Sayn Wittgenstein, who have all published accounts of them which breathe an air of sincere belief. Professor Crookes got in touch with this new medium in December, 1873. In _The Spiritualist_--a journal edited by Mr. Harrison, at whose home several sittings had taken place--there appeared in the numbers for February and March, 1874, two letters from Professor Crookes. A few extracts from these letters here follow: I have reason to know that the power at work in these phenomena, like Love, "laughs at locksmiths." The seance of which you speak and at which I was present, was held at the house of Mr. Luxmore, and the "cabinet" was a back drawing-room separated from the front room in which the company sat by a curtain. The usual formality of searching the room and examining the fastenings having been gone through, Miss Cook entered the cabinet. After a little time the form of Katie appeared at the side of the curtain, but soon retreated, saying her medium was not well, and could not be put into a sufficiently deep sleep to make it safe for her to be left. I was sitting within a few feet of the curtain close behind which Miss Cook was sitting, and I could frequently hear her moan and sob, as if in pain. This uneasiness continued at intervals nearly the whole duration of the _seance_, _and once, when the form of Katie was standing before me in the room, I distinctly heard a sobbing, moaning sound, identical with that which Miss Cook had been making at intervals the whole time of the seance, come from behind the curtain where the young lady was supposed to be sitting_. I admit that the figure was startlingly life-like and real, and, as far as I could see in the somewhat dim light, the features resembled those of Miss Cook; but still the positive evidence of one of my own senses that the moan came from Miss Cook in the cabinet, whilst the figure was outside, is too strong to be upset by a mere inference to the contrary, however well supported.