On Laplace's Correction for the Velocity of Sound. 41 

 II. A 12-inch vertical tube. Caoutchouc with four orifices. 



Water passing through the tube 

 per second. 



Air passing 

 i through the tube 

 per second. 



Number of impulses 

 per second. 



cub. centims. 



cub. centims. 





25 



! Air did not enter. 



"J Could not be deter- 



20 



•811 



mined on account 



13-888 



2-617 



> of the too rapid 



13157 



2-994 



coalescence of the 



10-638 



4000 



J air-discs. 



4-504 Highest note produced. 



4032 



598 



3*731 Lower note than preceding. 



3-496 



506 



2941 „ 



3-759 



46-9 



2439 „ 



3333 



37-5 



f Most base note, deeper") 

 2-325 -j than any note produced > 

 in Experiment I. 







3-086 



350 







1-018 Distinct impulses. 



2-293 



19-8 



IV. On Laplace's Correction for the Velocity of Sound. 

 By John Tyndall, F.R.S. 



To the Editors of the Philosophical Magazine and Journal. 



Gentlemen, 



IN the last November Number of the Philosophical Magazine I 

 published a brief " Note on Laplace's Correction for the Theo- 

 retic Velocity of Sound/' the main point of which was to show 

 that the extraordinary radiant and absorbent power which recent 

 experiments have proved to be possessed by various gases and 

 vapours, would, in all probability, affect the correction to be 

 applied to the velocity of sound through such gases and vapours. 

 The portion of the note which refers to this point, resting as it 

 does on sure experiments, will, I think, always retain its force 

 and pertinence: this portion terminates with the words "nor 

 could a correct ratio be deduced from the velocity of sound in 

 the medium." 



The remaining portion of the note I would ask permission to 

 cancel for the present. I have recently made some experiments 

 with a view to testing the possible influence of radiation; and 

 if the continuance of these should lead to any definite result, 

 they shall in due time be communicated to the Philosophical 

 Magazine. 



T am, Gentlemen, 



Your obedient Servant, 



John Tyndall, 



