438 



NA TURE 



\_March 6, 1884 



THE SIX GA TE WA YS OF KNO WLEDGE '- 



T THANK you most warmly for the honour you have done me 

 in electing me to be your jiresident. I value the honour very 

 highly ; but when I look at the list of distinguished men who 

 have preceded me in the office, I feel alarmed at the responsi- 

 bility I have undertaken. A very pleasing duty, however, has 

 been already performed in the interesting and not onerous 

 function we have now gone through. I would gladly speak on 

 the several subjects, for merit in the study of which these prizes 

 have been awarded ; but I am afraid that if I were to do so, it 

 would be more for my own gratification than for your pleasure 

 and profit, and I feel that I shall best consult your wishes in 

 passing on at once to the subject of the address which it becomes 

 my duty to give. 



The title of the subject upon which I am going to speak this 

 evening might be — if I were asked to give it a title — "The Six 

 Gateways of Knowledge." I feel that the subject I am about 

 to bring before you is closely connected with the studies for 

 which the several prizes have been given. The question I am 

 going to ask you to think of is : What are the means by which 

 the human mind acquires knowdedge of external matter? 



John Bunyan likens the human -oul to a citadel on a hill, self- 

 contained, having no means of communication with the outer 

 world, except by five gates — Eye Gate, Ear Gate, Month Gate, 

 Nose Gate, and Feel Gate. Bunyan clearly was in want of a 

 word here. He u^es "feel" in the sense of "touch," a 

 designation which to this day is so commonly used that I can 

 scarcely accuse it of being incorrect. At the same time, the more 

 correct and distinct designation undoubtedly is, the sense of 

 touch. The late Dr. George Wilson, first Professor of Tech- 

 nology in the University of Edinburgh, gave, some time before 

 his death, a beautiful little book under the title of " The Five 

 Gateways of Knowledge," in which he quotes John Bunyan in 

 the mmner t have indicated to you. But I have said six gate- 

 ways of knowledge, and I must endeavour to justify this saying. 

 I am going to try to prove to you that we have .six senses — that 

 if we are to number the senses at all we must make them six. 



The only census of the senses, so far as I am aware, that ever 

 made them more than five before was the Irishman's reckoning 

 of seven senses. I presume the Irishman's seventh sense was 

 common sense ; and I believe that the large possession of that 

 virtue by my countrymen — -I sjDeak as an Irishman — I say the 

 large possession of the seventh sense, which I believe Irishmen 

 have, and the exercise of it, will do more to alleviate the woe^ of 

 Ireland than even the removal of the melancholy ocean which 

 surrounds its shores. Still I cmnot scientifically see how we can 

 make more than six senses. I shall, however, should time per- 

 mit, return t ) this question of a seventh sense, and I shall 

 endeavour to throw out suggestions towards answering the 

 question — Is there, or is there not, a magnetic sense? It is 

 possible that there is, but facts and observations so far give us 

 no evidence that there is a magnetic sense. 



The six senses that I intend to explain, so far as I can, this 

 evening, are according to the ordinary enumei"ation, the sense of 

 sight, the sense of hearing, the sense of smell, the sense of taste, 

 and the sense of touch, divided into two departments. A 

 hundred years ago Dr. Thomas Reid, Professor of Moral Philo- 

 sophy in the University of Glasgow, pointed out that there was 

 a broad distinction between the sense of roughness or of resist- 

 ance, which was possessed by the hand, and the sense of heat. 

 Reid's idea has not I think been carried out so much as it de- 

 serves. We do not, I believe, find in any of the elementary 

 treatises on natural philosophy, or in the physiologists' writings 

 upon the senses, a distinct reckoning of six senses. We have a 

 great deal of explanation about the muscular sense, and the 

 tactile sense ; but we have not a clear and broad distinction of 

 the sense of touch into two departments, which seems to me to 

 follow from Dr. Thomas Reid's way of explaining the sense of 

 touch, although he does not himself distinctly formulate the dis- 

 tinctio 1 I am now going to explain. 



The sense of touch, of which the organ commonly considered 

 is the hand, but which is possessed by the whole sensitive sur- 

 face of the body, is very distinctly a double quality. If I touch 

 any object, I ])erceive a complication of sensations, I perceive 

 a certain sense of roughness, but I also perceive a very distinct 

 sensation, which is not of roughness, or of smoothness. There 

 are two sensations here, let us try to analyse them. Let me dip 



' An Address at the Midland Instilute. Birmingham, October 3, 1883, by 

 Prof. Sir William Thomson, IJ..D., F.R.S., president. 



my hand into this bowl of hot water. The moment I touch the 

 water, I perceive a very distinct .sensation, a sensation of heat. 

 Is that a sensation of roughness, or of smoothness? No. Again, 

 1 dip my hand into this basin of iced water, 1 perceive a very 

 distinct sensation. Is this a sensation of roughness, or of 

 smoothness ? No. Is this comparable with that former sensa- 

 tion of heat ? I say yes. Although it is opposite, it is compar- 

 able with the sensation of heat. I am not going to say that we 

 have two sensations in this department — a sensation of heat, and 

 a sensation of cold. I shall endeavour to explain that the per- 

 ceplions of he.at and of cold are perceptions of different degrees 

 of one and the same quality, but that that quality is markedly 

 different from the sense of roughness. Well now, what is this 

 sense of roughness ? It will take me some time to explain it 

 fully. I shall therefore say in advance that it is a sense of force ; 

 and I shall tell you in advance, before I justify completely what 

 I have to say, that the six senses, regarding which I wish to give 

 some explanation, are : the sense of sight, the sense of hearing, 

 the sense of taste, the sense of smell, the sense of heat, and the 

 sense of force. The sense of force is the sixth sense ; or the 

 senses of heat and of force are the sense of touch divided into 

 two, to complete the census of six that I am endeavouring to 

 demonstrate. 



Now I have hinted at a pos-ible seventh sense — a magnetic 

 sense — and though out of the line I propose to follow, and 

 although time is precious, and does not permit much of di- 

 gression, I wish just to remove the idea that I am in any way 

 suggesting anything towards that wretched superstition of 

 animal magnetism, and table-turning, and sinritualism, and mes- 

 merism, and clairvoyance, and spirit-wrapping, of which we 

 have heard so much. There is no seventh sense of the mystic 

 kind. Clairvoyance, and the like, are the result of bad ob- 

 servation chiefly, somewhat mixed up, however, with the effects 

 of wilful imposture, acting on an innocent, trusting mind. But 

 if there is not a distinct magnetic sense, I say it is a very great 

 wonder that there is not. 



Many present know all about magnetism. A very large 

 number of pupils have gained an immense anount of valuable 

 knowledge in various subjects, from the classes carried on 

 nightly within the walls of the Birmingham and Midland Insti- 

 tute ; and I can see from the prizes that have been awarded, and 

 that I have just now had the pleasure of distribuiing for excel- 

 lence and proficiency in this department, that many have learned 

 of magnetism. I had the pleasure of seeing the class-rooms this 

 morning, and I wished I could be in them in the evening to see 

 the studies as carried on in them every evening. Well now, the 

 study of magnetism is the study of a very recondite subject. We 

 all know a little about the mariner's compass, the needle 

 pointing to the north, and so on ; but not many of us have gone 

 far into the subject, and not many of us understand all the recent 

 discoveries in electromagneti^m. I could wish, had I the appa- 

 ratus here, and if you would allow me, to show you an experi- 

 ment in magneti-m. If we had before us a jiowerful magnet, 

 or say the machine that is giving us this beautiful electric light 

 liy which the hall is illuminated, it, serving to excite an electro- 

 magnet, would be one part of our apparatus ; the other part 

 would be a piece of copper. Suppose then we had this appar- 

 atus, I -would show you a very wonderful discovery made by 

 Faraday and worked out admirably by Foucault, an excellent 

 French experimenter. I have said that one part of this appar- 

 atus would be a piece of copper, but silver would answer as 

 well. Probably no other metal than copper or silver — certainly 

 no other one, of all the metals that are well known, and obtain- 

 able for ordinary experiments — possesses, and no other metal or 

 substance, whether metallic or not, is kno^n to possess, in any- 

 thing like the same decree as copper and silver, the quality I am 

 now going to call attention to. 



The quality I refer to is "electric conductivity," and the 

 result of that quality in the experiment I am now going to de- 

 scribe is, that a piece of copper or a piece of silver, let fall 

 between the poles of a magnet, will fall down slo«ly as if it 

 were falling through mud. I take this body and let it fall. 

 Many of you here will be able to calcul ite what fraction of a 

 second it takes to fall one foot. If I took this piece of copper, 

 placed it just above the space between the poles of a powerful 

 electromagnet and let it go, you would see it fall .slowly down 

 before you ; it would perhaps take a quarter of a minute to fall 

 a few inches. 



This experiment was carried out in a most powerful manner 

 by Lord Lindsay (now Lord Crawford), assisted by Mr. Crom- 



