Slade goes to the séance armed, among other things, with an empty, counterfeit box resembling Zöllner's, also with a five-mark piece of the right date--I think that even Zöllner would have been suspicious if the coin that fell on the slate had been dated 1878! Zöllner shakes _his_ box--the genuine one--and satisfies himself that the coin is really there. Then follows a little preliminary play with the slate and so on, the simplest matter in the world to an artist like Slade. At the critical moment Slade diverts the attention of the experimenters from the table by the world-old conjuror's dodge of gazing fixedly in some other direction and murmuring "I see--see--funf," etc. While Zöllner and his colleagues are glancing in the same direction to see what he is looking at, Slade swiftly substitutes his counterfeit box for the original, and the trick is to all intents and purposes done. All he has now to do is to drop the coin which he brought with him on to the slate at any convenient moment and draw out the latter in triumph! Given the astounding guilelessness of Zöllner and the complete lack of control revealed by the records, the thing was absurdly simple. And yet Zöllner refers to it as having been performed under "such stringent conditions!" The foregoing example will, I hope, make quite clear how much importance I attach to the Slade-Zöllner investigations. I am not prepared to say that Slade never produced genuine phenomena, either with Zöllner or with anyone else. On the contrary, I think it probable that he possessed a certain amount of genuine mediumistic power which, however, he did not hesitate to supplement by cheating when occasion offered. Some, or for that matter all, of the Slade-Zöllner experiments may happen to have been genuine. But in view of the known untrustworthiness of Slade and the complete lack of proper scientific control revealed by a study of the published records we must write them off as quite valueless from a scientific point of view. I have dealt with this particular case at some length partly on account of the vehemence of the controversies which have raged round it and partly because the discrediting of Zöllner's observations has done much to bring the whole idea of the fourth dimension into disfavour and even into ridicule. This, I feel, is unfair and I wish to make it clear that my present advocacy of the claims of the higher space hypothesis is in no way based on the Zöllner experiments. There are, of course, in the literature of the subject a large number of other cases which are not so obviously unreliable--some, in fact, which are distinctly good. Dr. S.A. Peters gives an account of an early experiment by Dr. Hare--one of the pioneer investigators--in which two small balls of platinum were transferred to the inside of two hermetically sealed glass tubes. It is not a bad case but is a very old one and the record gives no particulars of any special precautions taken to exclude fraud.