VIBRATIONS OF STRINGS 855 



34. Vibrations of Strings. Overtones. Resonance. 

 ^imbre. Musical notes are very frequently produced 



v the vibration of solid bodies, which, when an alteration 



./ 



f their form or position has been produced by the appli- 

 ition of some force, are afterwards left to themselves. 

 Iris is the case in bells, tuning-forks, drums, cymbals, 

 le glass or steel harmonicon, &c., but especially in 

 1 stringed instruments. The investigation of the 

 ibrations of strings throws light on many acoustic 

 ibienomena ; the construction of a simple apparatus for 

 le purpose is therefore strongly recommended. 

 i If a cord be tightly stretched between two strong 

 ;iils, which are driven into two short ledges firmly 

 ;^ed to a brick wall, and the cord be plucked with the 

 ngers, or a violin -bow be drawn across it, the cord will 

 i: seen to vibrate like the string of a musical instru- 

 lent, but little or no sound will be heard. The surface 

 c the string is so small, its points of contact with the 

 }.' are so few, that the pulsations imparted to the 

 i- are not sufficiently vigorous to produce a strong 

 sand. For this it is necessary that the motion of the 

 sing should be communicated to a large, thin, and 

 fit sounding-board, as in the experiments on the cou- 

 rt ion of sound; the sounding-board takes up the 

 v .rations of the string and communicates them by its 

 .re surface to the surrounding air. For similar 

 sons, all stringed instruments are provided with 

 *< riding-boards or sounding-boxes. For acoustic 

 instigations, an apparatus is employed called a 

 Miometer' or 'monochord.' 



monochord sufficient for our purposes is shown in fig. 214. 

 ] l'e a kind of box without bottom made by a joiner, if possible 



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