286 MUSICAL INSTRUMENTS 



eight in the piano ; the hammer of the piano is replaced in 

 the violin by the bow, and in the guitar by the fingers ; vary- 

 ing pitches on any one string are obtained by sliding a finger 

 of the left hand along the wire, and thus altering its length. 

 Frequent tuning is necessary, because the fine adjustments 

 are easily disturbed. The piano is the best protected of all 



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FIG. 180. Front view of an open piano. 



the stringed instruments, being inclosed by a heavy frame- 

 work, even when in use. 



267. Strings and their Tones. Fasten a violin string to a 

 wooden frame or box, as shown in Figure 181, stretching it 

 by means of some convenient weight ; then lay a yard- 

 stick along the box in order that the lengths may be deter- 

 mined accurately. If the stretched string is plucked with 

 the fingers or bowed with the violin bow, a clear musical 

 sound of definite pitch will be produced. Now divide the 



