THE SIX GATE W 'A YS OF KNOWLEDGE. 265 



hear the sounds that he called forth from the 

 instrument. Hence, besides the Ear Gate of 

 John Bunyan, there is another gate or access for 

 the sense of hearing. 



What is it that you perceive ordinarily by the 

 ear that a healthy person, without the loss of 

 any of his natural organs of sense, perceives with 

 his ear, but which can otherwise be perceived, 

 although not so satisfactorily or completely ? It 

 is distinctly a sense of varying pressure. When 

 the barometer rises, the pressure on the ear 

 increases ; when the barometer falls, that is an 

 indication that the pressure on the ear is diminish- 

 ing. Well, if the pressure of air were suddenly to 

 increase and diminish, say in the course of a 

 quarter of a minute suppose in a quarter of a 

 minute, the barometer rose one-tenth of an inch, 

 and fell again ; would you perceive anything? I 

 doubt it ; I do not think you would. If the 

 barometer were to rise two inches, or three inches, 

 or four inches, in the course of half a minute, most 

 people would perceive it. I say this as a result of 

 observation, because people going down in a 



