394 Prof. C. V. Raman on the " Wolf-note " 



This is readily shown by putting a mute on the bridge. The 

 pitch of the wolf-note then falls immediately by a considerable 

 interval. On the particular 'cello I use, a load of 17 grammes 

 fixed at the highest point of the bridge lowers the wolf-note 

 pitch from 176 to 160 vibrations per second. A larger load 

 of 404 grammes depresses it further to 137 vibrations per 

 second, and also causes two new bat comparatively feeble 

 resonance-points to appear at 100 and 184 respectively, 

 without any attendant cyclical phenomena. An ordinary 

 brass mute has a very similar effect. 



The Formation of Violin-tone and its Alteration by a Mute, 



The positions of the frequencies of maximum resonance of 

 the bridge and associated parts of the belly for notes over 

 the whole range of the scale are undoubtedly of the highest 

 importance in determining the character of violin-tone, and 

 the explanation of the effect of a mute on the tone of the 

 instrument is chiefly to be sought for in the effect of 

 the loads applied on the frequencies of the principal free 

 modes of vibration of the bridge and associated parts of the 

 belly. The observations of Dr. P. H. Edwards on the effect 

 of the mute * are evidently capable of explanation on the 

 basis of the lowering of the frequencies of maximum reso- 

 nance by the loading of the bridge. But a more detailed 

 understanding of the dynamics of the problem requires 

 further theoretical and experimental investigation. Recently, 

 I have secured an extensive series of photographs showing 

 the effect on the motion of the bridge in its own plane pro- 

 duced by fixing a load on it at one or other of a variety of 

 positions. The close parallelism between the effect of loading, 

 as shown by these photographic curves and as observed by 

 the ear, seems to show that the motion of the bridge in its 

 own plane determines the quality of violin-tone to a far 

 greater extent than might be supposed from the work of 

 Giltay and De Haas "|\ A detailed discussion of this and 

 other problems relating to the physics of bowed instruments 

 is reserved for a separate communication. 



This investigation was carried out in the Laboratory 

 of the Indian Association for the Cultivation of Science, 

 Calcutta. 



20th May, 1916. 



* P. H. Edwards, Physical Review, January 1911. 



t Giltay and De Haas, Proc. Roy. Soc. Amsterdam, January 1910. 

 See also E. H. Barton and T. F. Ebblewhite, Phil. Mag, September 1910, 

 and C. V. Raman, Phil. Mag. May 1911. 



