134 Mr. Meikle on the 



This Mr. Ivory has rejected, without showing cause why. Most 

 probably he did not Hke it after it was well known not to be 

 his own production, and especially after I had advanced so 

 much in its favour. Except the index of 5, it is M. Poisson's 

 formula. The reasons why that index should be ^ are given ia 

 Edin. New Phil. Jour. vol. ii. 333, 391, and iv. 101. 



I formerly remarked that the notes of music afforded no 

 satisfactory proof that sounds of all intensities are propagated 

 with equal velocities. Another alleged proof, apparently of 

 more weight, has been drawn from the experiments made in 

 France in 1822 ; where the velocity of sound appeared to be 

 the same, whether the guns were charged with two or with three 

 pounds of powder. When, however, as was the case there, the 

 powder has almost nothing to propel, a considerable proportion 

 of it escapes without catching fire, and so much the more as 

 the charge in the same size of gun is greater : so that the re- 

 ports from the two and the three pounds of powder, might not 

 differ materially in sharpness. Nor can I attach any stress to 

 equal or uniform velocities deduced from hypothetical data ; 

 for we have seen that one of the most natural and obvious in- 

 ferences from the projectile theory just discussed, is that the 

 velocity ought to decrease rapidly ; which is curious enough 

 when we recollect that those who follow this mode of investi- 

 gation assume, without hesitation, that it accords with a uni- 

 form velocity. No solution of the problem can be legitimate, 

 if it take for granted an element so important, but so dubious, 

 as uniformity of velocity, — an element which, I presume, can 

 only be settled by experiment. For, I think it will be found 

 that in solutions of this problem, the uniformity of the propa- 

 gation of sound, or its independence of intensity, is, at best, 

 assumed, or not provided for. In some cases, as we have 

 seen, it may be got over quietly by inaccurate working ; by re- 

 peatedly rejecting terms from the calculus, without giving any 

 good reason, or showing that such terms could not have influ- 

 enced the result. 



If the velocity of sound be really greater when it is more in- 

 tense, then all attempts to bring out a legitimate and definite 

 mathematical result must necessarily prove abortive ; because 

 the intensity, being of an indeterminate character, cannot^ as 



