

THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



DECEMBER 1868. 



LI. On the Communication of Vibration from a Vibrating Body 

 to a surrounding Gas, By G. G. Stokes, M.A., D.C.L., 



Sec. R.S., Fellow of Pembroke College, and Lucasian Professor 

 of Mathematics in the University of Cambridge*. 



IN the first volume of the Transactions of the Cambridge 

 Philosophical Society is a short paper by Professor John 

 Leslie, " On Sounds excited in Hydrogen Gras," in which the 

 author mentions some remarkable experiments indicating the 

 singular incapacity of hydrogen for becoming the vehicle of the 

 transmission of sound when a bell is struck in that gas, either 

 pure or mixed with air. With reference to the most striking of 

 his experiments, the author observes (p. 267), " The most re- 

 markable fact is, that the admixture of hydrogen gas with atmo- 

 spheric air has a predominant influence in blunting or stifling 

 sound. If one half of the volume of atmospheric air be extracted 

 [from the receiver of the air-pump], and hydrogen gas be ad- 

 mitted to fill the vacant space, the sound will now become 

 scarcely audible." 



No definite explanation of the results is given ; but with refer- 

 ence to the feebleness of sound in hydrogen the author observes, 

 " These facts, I think, depend partly on the tenuity of hydrogen 

 gas, and partly on the rapidity with which the pulsations of 

 sound are conveyed through this very elastic medium;" and he 

 states that, according to his view, he " should expect the inten- 

 sity of sound to be diminished 100 times, or in the compound 

 ratio of its tenuity and of the square of the velocity with which 

 it conveys the vibratory impressions." With reference to the 

 effect of the admixture of hydrogen with air he says, " When 



* From the Philosophical Transactions for 1868, Part II., having been 

 read June 18, 1868. 



Phil. Mag. S. 4. Vol. 36. No. 245. Dec. 1868. 2 D 



