140 PSTCHOLOOT. 



The tympanic membrane is furthermore able to render 

 sensible differences in the pressure of the external atmos- 

 phere, too slight to be felt either as noige or in this more 

 violent way. If the reader will sit with closed eyes and let 

 a friend approximate some solid object, like a large book, 

 noiselessly to his face, he will immediately become aware 

 of the object's presence and position — likewise of its de- 

 parture. A friend of the writer, making the experiment 

 for the first time, discriminated unhesitatingly between the 

 three degrees of solidity of a board, a lattice-frame, and a 

 sieve, held close to his ear. Now as this sensation is never 

 used by ordinary persons as a means of perception, we may 

 fairly assume that its felt quality, in those whose attention 

 is called to it for the first time, belongs to it qua sensation, 

 and owes nothing to educational suggestions. But this felt 

 quality is most distinctly and unmistakably one of vague 

 spatial vastness in three dimensions — quite as much so as 

 is the felt quality of the retinal sensation when we lie on 

 our back and fill the entire field of vision with the empty 

 blue sky. When an object is brought near the ear we im- 

 mediately feel shut in, contracted ; when the object is 

 removed, we suddenly feel as if a transparency, clearness, 

 openness, had been made outside of us. And the feeling 

 will, by any one who will take the pains to observe it, be 

 acknowledged to involve the third dimension in a vague, 

 unmeasured state.* 



The reader will have noticed, in this enumeration of 

 facts, that voluminousness of the feeling seems to hear very little 

 relation to the size of the organ that yields it. The ear and 

 eye are comparatively minute organs, yet they give us feel- 

 ings of great volume. The same lack of exact proportion 

 between size of feeling and size of organ affected obtains 

 within the limits of particular sensory organs. An object 

 appears smaller on the lateral portions of the retina than it 

 does on the fovea, as may be easily verified by holding the 



* That the sensation in question is one of tactile rather than of acoustic 

 sensibility would seem proved by the fact that a medical friend of the 

 •writer, both of whose membrarue tympani are quite normal, but one of 

 whose ears is almost totally deaf, feels the presence and withdrawal of ob- 

 jects as well at one ear as at the other. 



