Polytechnic Association. G45 



The most remarkable fact shown by Mr. Mendenhall's experiments 

 is that perception is quicker through the ear than through the eye. 



Dr. J. "W. Richards — The sense of hearing seems to be more rapid 

 than the sense of sight. And if the body producing the sound was 

 not very near the ear, the time occupied by the sound in reaching the 

 ear must be taken into account. 



Dr. P. H. Yan der Weyde — The sound would move two feet in 

 l-550th of a second ; so that that would not make much difference. 



Mr. Partridge- — Probably the persons were directed to look at the 

 opening. In order to see a motion we should not look directly 

 towards the body which is to .move, but near it. The persistence of 

 the impression is greatest in that portion on which falls the image of 

 the object which we are looking directly at. The persistence of the 

 impression on the retina adds to the time required to perceive the 

 change. 



Dr. J. Y. C. Smith — It may be well to explain a little of the 

 anatomy of these organs, that it may be understood more clearly why 

 the mind receives impressions more quickly through the ear than 

 through the eye. Light traverses space at the rate of nearly 200,000 

 miles per second ; but yet an impression remains a considerable time 

 upon the retina before the mind is cognizant of it. Sound moves only 

 about 1,100 feet in a second ; yet the acoustic apparatus is such that 

 the mind is reached more quickly through the ear than through 

 the eye. The ear is so constructed that any disturbance in the 

 air is conducted in whirls and concentrated upon a drum-head. On 

 the opposite side of the drum-head there is a little bone attached to 

 the drum, and between that and the interior part of the ear are four 

 small bones : one looking like a hammer, another like an anvil, and 

 one, called the stapes, resembling a stirrup ; and these bones consti- 

 tute a compound lever increasing the motion produced by the vibra- 

 tion of the drum-head, and carrying it to the sac in which the 

 acoustic nerve is placed. 



"We see one object with two eyes, because the two images fall on 

 exactly corresponding parts of the two retinas. If we press upon the 

 eye, so that the images do not fall on corresponding parts, we see two 

 images. It is probably a matter of education to learn to see one 

 object with both eyes. I am satisfied that infants in the cradle do 

 not see very 'distinctly. The fluid of the aqueous humor is so turbid 

 that it is like looking through ground glass. And the same is the 

 ease with young birds, puppies and all young animals. By-and-by 

 this is absorbed, and a purer fluid takes its place, and they see more 



