In addition to the experiments of Crookes, it is fitting to add in this place those of the great English naturalist, Alfred Russel Wallace, also a member of the Royal Society of London, President of the English Anthropological Society, and well known as the scientist, who at the same time with Darwin (June, 1858), gave to the world the theory of the variation of species by natural selection. He himself gives the following account[69] of his studies in this matter of the mysterious psychic force: It was in the summer of 1865 that I first witnessed any of the phenomena of what is called Spiritualism, in the house of a friend,--a sceptic, a man of science, and a lawyer, with none but members of his own family present. Sitting at a good-sized round table, with our hands placed upon it, after a short time slight movements would commence--not often "turnings" or "tiltings" but a gentle intermittent movement, like steps, which after a time would bring the table quite across the room. Slight but distinct tapping sounds were also heard. The following notes made at the time were intended to describe exactly what took place:-- "July 22nd, 1865.--Sat with my friend, his wife, and two daughters at a large loo table, by daylight. In about half an hour some faint motions were perceived, and some faint taps heard. They gradually increased; the taps became very distinct, and the table moved considerably, obliging us all to shift our chairs. Then a curious vibratory motion of the table commenced, almost like the shivering of a living animal. I could feel it up to my elbows. These phenomena were variously repeated for two hours. On trying afterwards, we found the table could not be voluntarily moved in the same manner without a great exertion of force, and we could discover no possible way of producing the taps while our hands were upon the table." On other occasions we tried the experiment of each person in succession leaving the table, and found that the phenomena continued the same as before, both taps and the table movement. Once I requested one after another to leave the table. The phenomena continued, but, as the number of sitters diminished, with decreasing vigor, and, just after the last person had drawn back, leaving me alone at the table, there were two dull taps or blows, as with a fist on the pillar or foot of the table, the vibration of which I could feel as well as hear.