Transmission of Musical Sounds. 225 



I 2. 



In all the experiments above alluded to, the sounds trans- 

 mitted were either mere noises, such as the blow of a hammer, 

 or, as in Herhold and Rafn's experiment, a single musical 

 sound, produced by striking a silver spoon attached to one end 

 of the conducting wire ; and in no case were any means em- 

 ployed for the subsequent augmentation of the transmitted 

 sound. I believe that, previous to the experiments which I 

 commenced in 1820, none had been made on the transmission 

 of the modulated sounds of musical instruments ; nor had it 

 been shown that sonorous undulations, propagated through 

 solid linear conductors of considerable length, were capable 

 of exciting, in surfaces with which they were in connexion, a 

 quantity of vibratory motion, sufficient to be powerfully audible 

 when communicated through the air. The first experiments 

 of this kind which I made were publicly exhibited in 1821, 

 and notices of them are to be found in the Literary Gazette, 

 Ackerman's Repository, and other periodicals of that year. 

 On June 30, 1823, a paper of mine was read by M. Arago, at 

 the Academy of Sciences in Paris, in which I mentioned these 

 experiments, and a variety of others relating to the passage of 

 sound through rectilinear and bent conductors *. I propose, 

 in the present instance, to give a more complete detail of these 

 experiments than I have yet published ; and at the same time 

 to add what additional facts my subsequent experience has 

 furnished me with on the same subject. 



| 3. 



Before proceeding any further, it will be necessary to make 

 a few observations on the augmentation of sound which results 

 from the connexion of a vibrating body with other bodies 

 capable of entering into simultaneous vibration with it. This 

 participation of the vibrations of an original sounding body is 

 called resonance, or reciprocation of sound. 



Sonorous bodies are audible (the extent of their excursions 

 being supposed equal) in proportion to the quantity of their 

 vibrating surfaces. Thus, a plate of glass or metal is capable 



* An abridgment appeared in the Ann. de Chimie, July, 1823, and the entire 

 paper in the Annals of Philosophy, August, 1823. 



