July 2, 1886.] 



SCIENCliJ. 



THE EXISTENCE OF A MAGNETIC SENSE. 



Since the day when Thales, about twenty-four 

 hundred years ago, rubbed a piece of amber on 

 silk and found that it attracted light particles, the 

 phenomena of magnetic action have been regard- 

 ed with feelings of awe and mystery. The 

 sti'ange entrancing of animals brought about by 

 an intense fixation of their gaze was referred to 

 'animal magnetism,' because nobody understood 

 either the one or the other. The discovery of the 

 magnetic needle, and its mysterious constant 

 pointing towards the north, added another ele- 

 ment to the wonders of magnetism. Mesmer 

 was keen enough to see, that, by explaining the 

 hypnotic phenomena to which he gave his name 

 as due to ' magnetism,' he was treading on safe 

 ground. That elastic cabinet of mysteries could 

 easily be made to accommodate another series of 

 peculiar facts, and the theory had thenceforth a 

 habitation and a name. The mere mention of so- 

 called magnetic cures is sufficient to suggest a 

 host of alleged facts and wonders. Although all 

 such phenomena assume that the human body is 

 susceptible to the influence of the magnetic field. 

 Baron Reichenbach, in a series of experiments 

 since become famous, was the first to attempt a 

 scientific proof of such an influence. He thus 

 described his ' sensitives,' who were variously 

 affected by the presence of a magnetic field : 

 some saw flames issumg from the poles ; some 

 had disagreeable organic sensations ; some were 

 benefited by it ; and so on. These experiments 

 were repeated by Professor Barrett of the EngUsh 

 Society for psychical research, but altogether with 

 negative results, until the young men who had 

 done such good service in the thought-ta-ansfer- 

 rence department were called in to describe the 

 effects of a magnetic field upon them. They saw 

 the fights issuing from the poles, and felt the pains 

 in the temples when very near the magnet. Before 

 these experiments, Sir William Thomson had 

 expressed the opinion that it would certainly be 

 strange if no magnetic sense existed . The fact that 

 nothing happened when he put his head between 

 the poles of a powerful magnet, he regards as 

 very wonderful. Finally, French observers have 

 recorded the fact that hypnotics who have re- 

 sponded to the suggestion that one-half of the 

 body is affected in a certain way (e.g., one arm is 

 insensitive) will have the affection transferred to 

 the other side of the body, and removed from the 

 first side (i.e., the other arm will become insensi- 

 tive), by the application of a magnet on the op- 

 posite side of the body. 



The above hasty sketch of what has been done 

 towards solving the question of the possible effect 



of a magnet on human nerves seems to suggest 

 that a rigid scientific test upon normal j)ersons is 

 highly desirable. It was to supply this want that 

 the experiments about to be described were under- 

 taken. ^ The special points which were borne in 

 mind were, 1°, to exclude the action of chance ; 

 and, 2°, to rule out all possible modes of sugges- 

 tion as to what was going on. We believe 

 that we accomplished these objects by using 

 the following method and apparatus. A large 

 and powerful electro-magnet was tipped on its 

 side and supported between two tables. The 

 head of the person to be tested (to be called ' the 

 subject ') was placed between the poles of the 

 magnet, with the forehead and back of the head 

 all but touching the jjoles. He was seated up- 

 right in a chau", with his head in a normal and 

 fairly comfortable position. The magnet and the 

 subject were on the third floor of the building. 

 In the room on the ground-floor there was a dyna- 

 mo-machine, which, when tm-ned by the operator, 

 generated the current. The magnet was con- 

 nected with the dynamo by heavy insulated wnes 

 passing out of the windows and along the wall of 

 the building. The su.bject and the operator com- 

 municated by a system of telegraphic signals : 

 otherwise they were completely isolated from one 

 another. 



At the first stage of the experiments the follow- 

 ing method was employed. After the operator 

 had received the signal that the subject was ready, 

 he did one of two things : 1. He turned the 

 current on, and when, after a short interval, the 

 subject signalled ' Change,' he turned it off, turn- 

 ing it on again when the second 'change' was 

 signalled ; 2. He began by doing nothing, turned 

 the current on at the first ' change,' and off at the 

 second. In either case he received a signal from 

 the subject when the observation was concluded. 

 In each observation the subject knew that the con- 

 dition of the magnet at the beginning and at the 

 end of the experiment was the same, but that in 

 the middle, between the two ' changes,' the time of 

 which he himself directed, the condition was differ- 

 ent. His object was to tell whether the magnet 

 was on or off at that intermediate time. His op- 

 portunities for judging were extremely favorable, 

 for he knew exactly when to expect the sensation 

 of a change from one condition to anoflaer ; and 

 he knew that in one case it would be change from 

 magnetization to demagnetization, and in the other 

 case a reverse change. He had simply to tell 

 which was which. It is evident that by mere guess- 

 work he would answer correctly one-half the time, 



1 The experiments were conducted in the psycho-physical 

 laboratory of the Johns Hopkins university. Dr. G. H. F. 

 Nuttall was associated with me in the work. 



