Since we are dealing here with a point of capital importance, I shall take the liberty of stating with some detail circumstances which seem opposed to the thesis maintained by M. Gasparin. These facts, or data, have as guarantee the testimony of a man whom I should like to be able to name, because his scientific culture and his character are known of all men. It was in his house and under his eyes that the events took place which I am going to relate. At the time when everyone was amusing himself with making tables turn and speak, or in directing the motions of lead-pencils, fixed in movable sockets, over sheets of paper, the children of the house amused themselves several times with this sport. At first, the responses obtained were such that you could see in them a reflex of the unconscious thought of the operators, a "dream of waking performers." Soon, however, the character of the replies seemed to change. It seemed as if what they revealed could hardly have emanated from the mind of the young interrogators. Finally, there was such an opposition to the commands given that M. N., uncertain as to the true nature of these manifestations in which a will different from the human will _seemed_ to appear, forbade their being called forth again. From that time forth, sockets and table rested undisturbed. A week had scarcely rolled by, after the events just narrated, when a child of the family, he who had formerly succeeded best in the table experiments, became the actor, or the instrument, in strange phenomena. The boy was receiving a piano-lesson, when a low noise sounded in the instrument, and it was shaken and displaced in such a way that pupil and teacher closed it in haste and left the room. On the next day, M. N., who had been informed of what had happened, was present at the lesson, given at the same time,--namely, when the dusk was coming on. At the end of five or ten minutes he heard a noise in the piano difficult to define, but which was certainly the kind of sound one would expect a musical instrument to produce. There was something about it musical and metallic. Soon after, the two front legs of the piano (which weighed over six hundred and sixty pounds) were lifted up a little from the floor. M. N. went to one end of the instrument and tried to lift it. At one time it had its ordinary weight, which was more than the strength of M. N. could manage; at another, it seemed as if it had no longer any weight at all, and opposed not the least resistance to his efforts. Since the interior noises were becoming more and more violent, the lesson was brought to a close, for fear the instrument might suffer some damage. The lesson was changed to the morning and given in another room situated on the ground floor. The same phenomena took place, and the piano, which was