15ft Mr. Cooper's Observations on the 



the case here described, no such sensation was produced : for, in 

 Mr. P's ear, the air, meeting with no impediment, could suffer 

 no compression ; since it found a passage, through the open 

 membrane, to the mouth, by means of the Eustachian tube. 



Mr. P — was liable to the sensation commonly called the 

 teeth being on edge, in the same degree as it exists in others; 

 and it was produced by similar acute sounds, as by the filing of 

 a saw, the rubbing of silk, &c. Its occurring in him seems to 

 disprove the idea which has been entertained of its cause ; for 

 it has been thought, that the close connection of the nerve 

 called the corda tympani with the membrana tympani, exposed 

 it to be affected by the motions of the malleus ; and that, as it 

 passes to nerves connected with the teeth, they would suffer 

 from the vibratory state of the nerve, produced by the agitations 

 of the membrane. But, in this case, as the membrane was en- 

 tirely destroyed on that side on which the sensation was pro- 

 duced, some other explanation must be resorted to ; and I see 

 no reason why this effect should not be referred to that part of 

 the auditory nerve which lines the labyrinth of the ear, which, 

 being impressed by acute and disagreeable sounds, would con- 

 vey the impression to the portio dura of the same nerve, and 

 to the teeth with which that nerve is connected. 



The external ear, though two distinct muscles are inserted 

 into it, is capable, in its natural state, of little motion; however, 

 when an organ becomes imperfect, every agent which can be 

 employed to increase its powers is called into action ; and, in 

 the case here described, the external ear had acquired a distinct 

 motion upward and backward, which was observable whenever 

 Mr. P — listened to any thing which he did not distinctly hear. 

 This power over the muscles was so great, that when desired 



