6 Lord Rayleigh on Bells. 



By the method above described there was no difficulty in 

 showing that the four tones correspond respectively to n = 2, 

 3, 4, 5. Thus for the gravest tone the vibration is elliptical 

 with 4 nodal meridians, for the next tone there are 6 nodal 

 meridians, and so on. Tapping along a meridian showed 

 that the sounds became less clear as the edge was departed 

 from, and this in a continuous manner with no suggestion of 

 a nodal circle of latitude. 



A question, to which we shall recur in connexion with 

 church bells, here suggests itself. Which of the various co- 

 existing tones characterizes the pitch of the bell as a whole ? 

 It would appear to be the third in order, for the founders give 

 the pitch as E nat. 



My first attempts upon church bells were made in Sep- 

 tember 1879, upon the second bell (reckoned from the 

 highest) of the Terling peal; and I was much puzzled to 

 reconcile the pitch of the various tones, determined by reso- 

 nators, with the effective pitch of the bell, when heard from 

 a distance in conjunction with the other bells of the peal. 

 There was a general agreement that the five notes of the 

 peal were 



#, g$, a%, b, e$, 



according to harmonium pitch, so that the note of the second 

 bell was b. A tone of pitch a% could be heard, but at that 

 time nothing coincident with b or its octaves. Subsequently, 

 in January 1880, the b was found among the tones of the 

 be 1 !, but at much higher pitch than had been expected. The 

 five gravest tones were determined to be 



?, a% d\ g% + , b"; 



so that the nominal note of the bell agreed with the fifth 

 component tone, and with no graver one. The octaves are 

 here indicated by dashes in the usual way, the c 1 immediately 

 below the d! being the middle c of the musical scale. 



Attempts were then made to identify the modes of vibra- 

 tion corresponding to the various tones, but with only partial 

 success. _ By tapping round the sound-bow it appeared that 

 the minima of beats for d' occurred at intervals equal to -} of 

 the circumference, indicating that the deformation in this 

 mode was elliptical (n=2), as had been expected. In like 

 manner #"# gave n = 3; but on account of the difficulty of 

 experimenting in the belfry, the results were not wholly 

 satisfactory, and I was unable to determine the modes for the 

 other tones. One observation, however, of importance could 

 be made. All five tones were affected with beats, from which 



