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CHAPTER VI. 



PROBLEM OF DIFFERENT MODES OF VIBRATION OF 

 BODIES IN GENERAL. 



NOT only the objects of which we have spoken 

 hitherto, strings and pipes, but almost all 

 bodies are capable of vibration. Bells, gongs, tun- 

 ing-forks, are examples of solid bodies ; drums and 

 tambourines, of membranes ; if we run a wet finger 

 along the edge of a glass goblet, we throw the 

 fluid which it contains into a regular vibration ; 

 and the various character which sounds possess 

 according to the room in which they are uttered, 

 shows that large masses of air have peculiar modes 

 of vibration. Vibrations are generally accom- 

 panied by sound, and they may, therefore, be con- 

 sidered as acoustical phenomena, especially as the 

 sound is one of the most decisive facts in indicating 

 the mode of vibration. Moreover, every body of 

 this kind can vibrate in many different ways, the 

 vibrating segments being divided by Nodal Lines 

 and Surfaces of various form and number. The 

 mode of vibration, selected by the body in each 

 case, is determined by the way in which it is held, 

 the way in which it is set in vibration, and the 

 like circumstances. 



The general problem of such vibrations includes 



