452 Prof. More and Dr. Fry on the Appreciation 



caused by any irregularity in a musical string on a violin or 

 harp, and illustrate the impurity o£ tone which must follow. 

 The curves show also that these irregularities are all taken 

 up by the bridge, and so no doubt extend to the sound-box 

 and the adjacent air. 



Looking now over the results as a whole for the bridge's 

 motion, it is noteworthy that the fundamental tone of the 

 string is also revealed in the vibration of the bridge. Whereas 

 it might have been thought that whether the string were up 

 or down the bridge would be equally deflected inwards 

 towards the string's centre"*. But if this were the case the 

 fundamental would be lost by the bridge, its slowest vibra- 

 tion being the octave. This, however, is not the case, as all 

 experience shows and as is confirmed by the curves. 



As to the general character of the vibrations of the bridge, 

 they seem to be intermediate in type between those of the 

 belly dealt with in the first paper and those of the air dealt 

 with in the second. 



University College, Nottingham, 

 Dec. 21, 1906. 



XXXV. On the Appreciation of Difference of Phase of Sound- 

 Waves. By L. T. Moee, Ph.D., Professor of Physics, and 

 H. S. FB.Y,Ph.D. } Instructor in Chemistry, 2 he University 

 of Cincinnati^ . 



ri^HE experiments described in this paper, in which an 

 JL attempt has been made to show that we can locate 

 sounds by an appreciation of the difference of phase of the 

 waves coming to the ears, were carried out during the winter 

 of 1902. Certain psychologists, to whom the results were 

 submitted, considered them to be inconclusive, and their 

 publication was postponed until additional work could be 

 done. But this winter Lord Eayleigh, in his Sidgwick 

 lecture J, described some experiments he had performed which 

 convinced him that we do locate sounds, partially at least, by 

 this means. As his method differs considerably from ours, 

 it seems best to publish these in spite of some incompleteness. 

 There have been several attempts made to prove that the 

 ear is capable of detecting phase-differences of sound-waves 

 as well as their amplitude and- complexity. Apparently the 

 attempts have not had much success, and Konig is perhaps 

 the only one who maintained that one could distinguish two 



* Compare the longitudinal form of Melde's experiment, see Eayleigh 's 

 < Theory of Sound,' 2nd ed. vol. i. p. 81. 

 t Communicated by the Authors. 

 \ See Phil. Mag. [6] xiii. p. 214 (1907). 



