406 



THE BODY AT WORK 



crowd. This latter point marks an interval of one-third of 

 this wave plus the wave which led up to it. At the end of the 

 ninth foot there is a crowding, though less marked this wave 

 plus the two preceding waves, divided into fourths. Within 

 these intervals are other points at which the molecules have 

 closed together, the distances from a nodal point depending 

 upon the number of waves involved, and, speaking generally, 

 growing less marked as the number increases. Such are the 

 very complex pulsatile movements which reach the ear. 



Every musical sound produced by a piano, a violin, or other 

 instrument, is compounded of a fundamental or prime tone, 

 and overtones, partial tones, or harmonics. The following 

 table shows the more important partial tones which accompany 

 the prime tone when the middle on a pianoforte is struck : 



Ratio. 



8 



7 



Number of 

 Overtone. 



7th 

 6th 



5th 



4th 



3rd 



2nd 



1st 



Octave 



256 



Fundamental 



