It is not necessary that a crowd should be numerous for the faculty of seeing what is taking place before its eyes to be destroyed and for the real facts to be replaced by hallucinations unrelated to them.As soon as a few individuals are gathered together they constitute a crowd, and, though they should be distinguished men of learning, they assume all the characteristics of crowds with regard to matters outside their speciality. The faculty of observation and the critical spirit possessed by each of them individually at once disappears. An ingenious psychologist, Mr. Davey, supplies us with a very curious example in point, recently cited in the Annales des Sciences Psychiques, and deserving of relation here. Mr. Davey, having convoked a gathering of distinguished observers, among them one of the most prominent of English scientific men, Mr. Wallace,executed in their presence, and after having allowed them to examine the objects and to place seals where they wished, all the regulation spiritualistic phenomena, the materialisation of spirits, writing on slates, &c. Having subsequently obtained from these distinguished observers written reports admitting that the phenomena observed could only have been obtained by supernatural means, he revealed to them that they were the result of very simple tricks."The most astonishing feature of Monsieur Davey＇s investigation," writes the author of this account, "is not the marvellousness of the tricks themselves, but the extreme weakness of the reports made with respect to them by the noninitiated witnesses. It is clear,then," he says, "that witnesses even in number may give circumstantial relations which are completely erroneous, but whose result is THAT, IF THEIR DESCRIPTIONS ARE ACCEPTED AS EXACT, the phenomena they describe are inexplicable by trickery.The methods invented by Mr. Davey were so simple that one is astonished that he should have had the boldness to employ them; but he had such a power over the mind of the crowd that he could persuade it that it saw what it did not see." Here, as always, we have the power of the hypnotiser over the hypnotised.Moreover, when this power is seen in action on minds of a superior order and previously invited to be suspicious, it is understandable how easy it is to deceive ordinary crowds.