302 VIBRATION OF STRINGS 



NUMBER "I 66 132 198 264 330 396 462 528 594 660 



OF VIBRATIONS > = = =.= = = = 



PER SECOND. } 2 x 66 3 x 66 4 x 66 5 x 66 6 x 66 7 x 66 8 x 66 9 x 66 10 x 6G 



NUMBER 1 



AND LENGTH OF M /I 2 /2 3 /3 4 /4 5 /5 6 /6 7 /7 8 /8 9 /9 1U /10 

 SEGMENTS. J 



A body is thus capable of producing notes which are 

 higher than its fundamental tone. These higher notes 

 are termed overtones ; overtones of which the numbers 

 of vibrations are whole multiples of those of the funda- 

 mental tone are termed harmonic overtones, or simply 

 harmonics. 



The string should be plucked quite close to one end, and under 

 no circumstances at more than one point. The loops which the 

 string makes being comparatively small, the difference between the 

 nodes and ventral segments cannot be well seen unless the observer 

 is quite close to the vibrating string. To render it visible, so-called 

 riders are used ; these are small pieces of paper about 5 mm broax] 

 and 15 mm long, bent at an acute angle (/\), and placed astrich 

 the cord. Such a rider remains almost unmoved upon the nodal 

 points of a vibrating cord, but is at once jerked off if placed mid\va\ 

 between two nodes. If the cord be touched at 30 cm , and riders bf 

 placed at the divisions 15, 45, 60, 75, 90, and 105 cm , the riders npoi 

 60 and 90 cm will remain upon their seats when the cord is plucks 

 (say at 10 era ), while all the others are thrown off. If other segment? 

 are produced, the effect will be similar. The plucking should tx 

 done cautiously, lest all the riders be thrown off. It is better to maki 

 the cord vibrate by drawing a violin-bow across it; the rider. 

 remain in that case at rest upon the nodes even if the bow it. 

 applied rather vigorously. The bow must previously be rubbed witlij 

 rosin, just as if it were used for a violin. 



Tune both strings until they are in unison. Pluck 

 or draw the bow across, one of the strings ; the othe; 

 string will immediately begin to vibrate without be in; 



