364 HISTORY OF ACOUSTICS. 



tion, by saying, that vibrations are communicated 

 so as always to be parallel to their original direc- 

 tion. And by following it out in this shape by 

 means of experiment, M. Savart was led, a short 

 time afterwards, to deny that there is any essential 

 distinction in these different kinds of vibration. 

 "We are thus led," he says 16 in 1822, "to consider 

 normal [transverse] vibrations as only one circum- 

 stance in a more general motion common to all 

 bodies, analogous to tangential [longitudinal and 

 rotatory] vibrations ; that is, as produced by small 

 molecular oscillations, and differently modified ac- 

 cording to the direction which it affects, relatively 

 to the dimensions of the vibrating body." 



These "inductions," as he properly calls them, 

 are supported by a great mass of ingenious experi- 

 ments; and may be considered as well-established, 

 when they are limited to molecular oscillations, 

 employing this phrase in the sense in which it is 

 understood in the above statement ; and also when 

 they are confined to bodies in which the play of 

 elasticity is not interrupted by parts more rigid 

 than the rest, as the sound-post of a violin 17 . And 

 before I quit the subject, I may notice a conse- 

 quence which M. Savart has deduced from his 

 views, and which, at first sight, appears to overturn 

 most of the earlier doctrines respecting vibrating 



16 An. Chim. t. xxv. p. 33- 



17 For the suggestion of the necessity of this limitation I 

 am indebted to Mr. Willis. 



