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I. "On the alteration of the Pitch of Sound by conduction 

 through different Media." By SYDNEY RINGER, Esq., 

 late Physicians' Assistant at University College Hospital. 

 Communicated by Dr. GARROD. Received November 25, 

 1859. 



Having observed that the pitch of cardiac murmurs underwent 

 various alterations dependent on the constitution of the conducting 

 body, the following experiments were devised to extend and render 

 more certain the observations made on the human subject. In most 

 of these experiments a tuning-fork was used, and in all the alterations 

 in pitch were tested by the ear. 



In making these experiments, the note of the vibrating fork was 

 first taken with the instrument close to the ear and without being 

 in contact with any resounding body. It was next placed on the body 

 which was experimented on, and lastly listened to through the medium 

 of the same. The alteration in pitch obtained by these two latter 

 methods gave always the same results in kind, but Dot in degree, 

 the alteration being always greater when the note was heard through 

 the medium of the conducting body. 



SOLIDS. 



A board 1 3 feet long was balanced on the back of two chairs. 

 The note of the fork was then taken, without its being in contact 

 with the board. The fork in vibration being next placed at one end 

 of the board, the ear was placed on the other, and the note was then 

 found to be most appreciably lowered in pitch. 



As boards composed of various kinds of wood were not obtainable, 

 tables were used. Of all the woods thus tested, deal lowered the 

 pitch most ; indeed the lowering of the pitch was always in proportion 

 to the porosity of the wood f . 



The pitch was found to fall the greater the distance from the fork. 



*Bone lowered it. 



Glass raised the pitch. 



Iron raised it. 



t Dr. Wylde, the Conductor of the Philharmonic Society, kindly examined and 

 fully corroborated, in those experiments marked with an asterisk, the conclusions 

 I had previously come to. All the experiments were confirmed by numerous 

 persons of acute ear. In no case was their opinion at variance with my own. 



