CHAP, in.] STRINGED INSTRUMENTS. 145 



of air must be otherwise quite isolated ; lie found that by making 

 openings in the sides, the tone became thinner in proportion as the 

 holes were wider, and also that the vibrations of the plates were 

 individually imperfect. 



The sides of the sounding-box of the violin and the mass of 

 inclosed air vibrate together in unison, as was also proved by Savart. 

 Nevertheless, taken separately, the two plates ought to give two 

 notes differing about a major second from each other. Nearer the 

 unison, they would cause beats or throbs in the notes : further off the 

 notes would be able to blend with difficulty. Moreover it is the 

 upper plate or belly which vibrates with most power : this is the 

 reason why it is necessary that the wood of this part of the instru- 

 ment should be fibrous, elastic and light. The lower plate or back 



4th string. 3rd string. 2nd string. 1st string. 



7 1 2 3 l~ |~ 2 3 41 2~ 3 4 

 4 J + 



+ _l_ 



FIG. 98. Finger-board of the violin; fingered. 



is designed to give a reciprocating resistance to the motion trans- 

 mitted from the belly ; .it has not merely to receive but to return the 

 impulses and intensify the shocks. If it were only equal to the belly 

 in rigidity only a see-saw motion would result adding nothing to 

 the power. 



The sound-post of a violin is a part of the instrument essential to 

 the sonorousness and the quality of its tones. According to 

 Savart, its function is to give out the normal vibrations of the two 

 or conjoined plates. To prove his view, he pierced the two plates 

 and vibrated the strings normally with the plates, by passing the 

 bow through the openings ; then the sound-post became useless. 



M. Daguin l on the other hand, in noticing Savart's opinion 



1 The theory of M. Daguin is untenable. The possibility of transversal drag of 

 the bridge is set aside by the fact that the acting string is one out of four, and the 

 tension of each string averages I81b. 54 against 18 holding the bridge in posi- 

 tion. The bridge is really supported on both feet, one by the sound-^ostf, the other 

 by the sound-&ar, else the strings least upheld by the post would burst the belly. 

 The value of the present arrangement is in its securing everywhere responsive 



L 



