i88 



NA TURE 



[June 20, 1895 



-.1 with very considerable accuracy. This leads me to 

 thu second e\|5eriment. (*) Let the observer, still with eyes 

 closed and bandaged, stand up and tie at liberty to move his 

 head. Let the assistant produce the clicking sound, not once 

 only, but again and again at short intervals, always in the same 

 place. The obser\er turns round until he faces the source of 

 sound. He knows that he is facing it when he hears it equally 

 loud in b.5th ears, and hears it to the right when he turns a 

 little to the left, and to the left when he turns a little to the right, 

 that is the criterion of whether the source is behind or before 

 him. Having now got the aziniuth, he seeks the altitude. 

 Moving his head about a right and left axis, he seeks the jxjsition 

 in which he hears the sound l)est. He is now looking towards 

 the source of the sound. 



The concha of the external ear acts as a screen, and it is 

 remarkable how much difference there is in the quality as well 

 as in the loudness of most sounds with different altitudes. 



Stand in front of a pi|)e from which water is rushing, and 

 move the head round a right and left axis, bow, in fact, to the 

 pipe, and a striking difference in the quality and loudness 

 of the sound will be observed in the different |X)sitions of 

 the head. 



It may Ik; said birds have no concha, and yet they perceive as 

 well as we do the direction of sound. But there is a method 

 by which, without any use of the action of the concha, and 

 by purely binaural observations, we can ascertain the direction 

 of sound. By one observation, as already described, we can 

 find a plane containing the line along which the sound reaches 

 us. That plane is at right angles to the line joining our two 

 ears. By moving the head we can shift the line joining our two 

 ears, and then by another similar observaiion obtain the plane 

 at right angles to the new position of the line joining the two 

 ears and containing the direction of sound. The direction of 

 sound is the intersection of these two planes. 



I do not think we use this method (allh<uigh I have tried it 

 and found it work), but we often see birds incline their heads 

 when listening in such a way as to suggest that they use it. 



There is another objection which is often brought ag.iinst the j 

 theory I have Ixren explaining. It is said, " Is it conceivable 

 that there should lie a special sense, common to man and all 

 vertebrate animals, which has remained unknown till about 

 twenty-two years ago ? This is a sense invented, not discovered 

 by scientilic men, otherwise we should all have known about its 

 existence at least." 



This objection is not one to be met by contempt ; it has a 

 real basis, and as I believe this sense to be a real one, I feel 

 bound to look for the cause of the incredulity. 



.\ six-cial sense is (xipularly understood to be a gateway of 

 knowledge. Information as to external things comes to us in 

 various ways, and each of these ways has from ancient time 

 been recognised and named as a special sense. But this is not 

 exactly the physiological way of looking at things. I may 

 illustrate the ilifference by a sort of analog)'. In a large busi- 

 ness estal)lishment the manager sits in his room upstairs. He 

 has various ways of getting information. The post brings him 

 letters, he lofiks at them ; some he carefully considers and 

 answers, others he looks at and puts into the waste-paper 

 lasket— but he has hxiked at them all. So we sec things; 

 many of the things we consider, take note of, others we pay no 

 attention to — do not an hour later remember anything about 

 them. But there are many messages which come to the busi- 

 ness establishment anil never reach (he manager's nmni at all. 

 They are allcndtd to by clerks in the oliice. They are not 

 futile, they are real mess.agcs and serve their purpose, a purpose 

 cssenlial lo the carr)'ing on of the business. If these were not 

 attended to downstairs, the manager would ver)' soon hear of it. 

 So with us. There are what we may call sensory impressions 

 which ilo not make their way lo the conscious li^, but arc all 

 the same properly attended lo by what in us correspon<ls lo the 

 clerks. If our clerks neglect Iheir work, the conscious Ego 

 ver)' S4)'m Iwcomes aware thai ihere is something wrong. 



In ihe case of ihc sense of rotation, ordinarily we |)ay no 

 attention lo its mess-iges — Ihc clerks at the sensory cenlres of 

 the ampullary nerves, and aX the motor cenlres of the muscles 

 of Ihc eyeUdls, do all thai is necessary. We ixrrceive the result 

 of Ihcir work in our visual sense of Ihe fixedness of ihe outside 

 world, anil we do not Irmilile ourselves as to how Ihe office work 

 has JK-'cn done. 



Hut and here I come lo a matter I referred to early in this 

 Irrtiire^the office work is vimeliines not well diine, and the 



NO. 1 338, VOL. 52] 



visual sense of the fixedness of the outside world is lost. If 

 this is due to disease, we send for the doctor and ask him to 

 find out what is wrong in the office, and, if he can. put it right. 

 But Ihere is a far more common cause of the loss of the visual 

 sense of the fixedness of the outside world, one which it has 

 not been left for two or three scientific men lo discover in the 

 last quarter of the nineteenth century. The most characteristic 

 effect of alcohol is to make all reflex actions sluggish. 

 Under the influence of a moderate dose of alcohol, what I 

 have called the office work, goes on all right but not quite 

 so fast as with no alcohol. The iness.age arrives, and the 

 answer is sent, but not quite so promiitly. The conscious 

 Ego may not note anything wrong, but a quantity of alcohol, 

 far short of a dangerously ix)isonous dose, may delay the 

 transmission of the signal to the muscles of the eyel)all so much 

 as to affect quite perceptibly the compens;ition of the move- 

 ments of the head. .V jwrfectly sober man sees the world wag 

 a little when he wags his head very vigorously — a i>oint of 

 light is perceptibly drawn out into a horizontal line of lights 

 the office work fails a little under such extreme pressure. But 

 a little alcohol makes the office work fail more readily, and as 

 the dose is increa.sed it fails altogether, and the sense vif the 

 fixedness of the world is wholly lost. Kven in such an extreme 

 case of intoxication, short of paralysis, thetlrunken man may see 

 the world steady, if only he can kee]) himself steady. I dare 

 say we have all seen very drunken men walking quite straight, 

 but with a preternatural fixeilness of the head. If anything 

 makes them move their head, they totter and reel. They move 

 the head a little : that happens to them in consequence of a 

 small and slow rotation of the head, which happens to us when 

 we wag our head violently, and they reel and stagger just as we 

 should reel and stagger if we tried to walk, violently wagging 

 our head all the lime. 



Just as there are blind men and deaf men, so there are men 

 who have lost or never had the sense of rotation. Such 

 persons are almost always deaf-mutes. The close anatomical 

 relation of the organ of heating and the organ of the sense of 

 rotatiiwi has this effect, that imperfect develoimienl of jiiitho- 

 logical injury of the one is usually associateil with similar defect 

 in the other. .\nil exjieriments on deaf-mutes have shown that 

 a large proportion of them are defective in the sense of rotation. 

 This is shown by the absence of the normal jerking of the eye- 

 IkiIIs when they are rotated, and by a perceptible insecurity in 

 their gait. They tlo not reel as driuiken men do, just as blind 

 men find their way about much belter than we could do if our 

 eyes were bandaged up : they have learned to gel on fairly well 

 with the help of ex]ierionce ami iheir other senses. 



I am not sure « helher in this account of the sense of rotation, 

 of its organ, and of the use of it, I have carried all my hearers 

 with me, and convinced you of Ihe real existence and real 

 practical use of ihis sense. I hope, however, I h:ive made it 

 clear thai the sulyect is worthy of attention, and that we 

 h.ave here matter fiir the careful consideration of physicists, 

 physiologists, and psychologists. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 

 OxKORi). — In a Convocation, held on Tuesday last, Iho 

 University, or at le.-ujt a section of it, displayed itself in an 

 unfavourable light. The Convocation House was crowded, not 

 because of the Statute on Research Degrees, which came before 

 the House, and passed its final stage without opposition, Imt 

 because of the proposid, which seemed to be a modest one, 

 that .\nthro|iology should be included anuing the subjects of the 

 I'inal .School of Natural Science, not as an extra, but as an 

 equivalent subjecl. This prmiosal was from Ihe first strongly 

 opposed by a few members of Congregation, but p.issed the two 

 readings in that body by subslanllal majorities. The opponents 

 of the subjecl, however, were not content to accept the results 

 of these voles, aiul issued an urgent whip to members of Convo- 

 cation, with the result that the statute was rejected by 68 votes 

 against 60. I'resumably the philosojihers, historians, and 

 divines who succeeded in throwing out the statute at its final 

 stage are pleased with their performance. To the outside world, 

 which is less than ever convinced that education is comprised 

 within the limits of the subjects of the School of l.iter.e 

 Humaniores, Iheir action will be but another instance of the in- 

 comjielency of a section of the classical world to understand 

 what is going on around ihem. The circular which was issued 



