The impression that results from the reading of all the official reports is not altogether satisfactory, and besides leaves us with our curiosity entirely ungratified. On the other hand, I can say, as I have already had occasion to remark, that, during the last forty years, almost all the celebrated mediums have been present at one time or another in my salon in the avenue l'Observatoire in Paris, and that I have detected them nearly all in trickery. Not that they always deceive: those who affirm this are wrong. But, consciously or unconsciously, they bring with them an element of trouble against which one is obliged to be constantly on guard, and which places the experimenter in conditions diametrically opposed to those of scientific observation. Apropos of Eusapia I had received from my illustrious colleague, M. Schiaparelli, director of the observatory at Milan, to whom science is indebted for so many important discoveries, a long letter from which I will quote a few passages: During the autumn of 1892 I was invited by M. Aksakof to be present at a certain number of Spiritualistic seances held under his direction and care, for the purpose of meeting the medium Eusapia Paladino, of Naples. I saw a number of very surprising things, a part of which, to tell the truth, could be explained by very ordinary means. But there are others the production of which I should not know how to explain by the known principles of natural philosophy. I add, without any hesitation, that, if it had been possible to entirely exclude all suspicion of deceit, one would have had to recognize in these facts the beginning of a new science pregnant with consequences of the highest importance. But it must be admitted that these experiments have been made in a manner little calculated to convince impartial judges of their sincerity. Conditions were always imposed that hindered the right comprehension of what was really taking place. When we proposed modifications in the program suited to give to the experiments the stamp of clearness and to furnish evidence that was lacking, the medium invariably declared that, if we did so, the success of the seance would thereby be made impossible. In fine, we did not _experiment_ in the true sense of the word: we were obliged to be content with _observing_ that which occurred under the unfavorable circumstances imposed by the medium. Even when mere observation was pushed a little too far, the phenomena were no longer produced or lost their intensity and their marvellous nature. Nothing is more offensive than these games of hide-and-seek to which we are obliged to submit