14 



Lord Rayleigh on Bells. 



The nodal circle for n — 2 has been verified experimentally 

 upon a bell constructed of thin sheet zinc in the form of fig. 5. 

 The gravest note, Gr#, and the corresponding mode of vibra- 

 tion, could be investigated exactly in the manner already 

 described. In each mode of this kind there were four nodal 



Fter. 4. 



Fij 



meridians, and a very well denned nodal circle. The situation 

 of this circle was not quite so low as according to calculation ; 

 it was almost exactly in the middle of the lower conical 

 segment. By merely handling the model it was easy to 

 recognize that it was stiff to forces applied at N, but flexible 

 higher up, in the neighbourhood of W, 



It is clear that the actual behaviour of a church bell differs 

 widely from that of a bell infinitely thin ; and that this should 

 be the case need not surprise us when we consider the actual 

 ratio of the thickness at the sound-bow to the interval 

 between consecutive nodal meridians. I think, however, that 

 the form of the bell does really tend to render the gravest 

 tone less prominent. 



Appendix. 

 On the Bending of a Hyperboloid of Revolution. 

 The deformation of the general surface of revolution was 

 briefly treated in a former paper *. The point whose original 



* "On the Infinitesimal Bending of Surfaces of Eevolution," Proc. 

 Math. Soc. xiii. p. 4 (1881). 



