1883.] On the Sound-post and Strings of the Violin. 243 



powerfully felt where the sound-post rests, which is at nearly the 

 thickest part of the back. These effects were very satisfactorily 

 observed on a violoncello, where the phenomena are on a larger scale. 



When the sound-post was removed from the violin, the large 

 difference of the amount of vibration on the two sides of the belly 

 was no longer present, the belly was about equally strongly agitated 

 on both sides, making allowance for the string which was bowed. 

 The tone became very poor and thin, as is well known to be the case 

 when the sound-post is removed. The vibration of the back was now 

 very feeble, as compared with its vibration when the sound-post was 

 present, a circumstance in favour of the view that the sound-post 

 conveys vibrations to the back. 



A clamp of wood was prepared which could be so placed on the 

 violin, as to connect by an arch of wood outside the violin the place 

 of the belly behind the bridge where the top of the sound-post 

 presses, with the place of the back where it rests. It was expected 

 that the wooden arch would restore to some extent the connexion of 

 belly and back which was broken by the removal of the post, and 

 carry, though imperfectly, vibrations from the upper plate to the 

 back. 



When this clamp was put on, the poor and thin sound was altered 

 to the fuller character of tone which belongs to the violin when the 

 sound-post is in its place. On testing the condition of the back its 

 normal state of vibration was found to be in a large degree restored. 

 If, while the strings were being bowed, the clamp was suddenly 

 removed, the tone at the same moment fell to its poor character, and 

 the vibration of the back as instantly diminished. 



It was further observed that if the upper part of the clamp pressed 

 upon the belly without the lower part coming into contact with the 

 back, the tone was altered in the same direction as when the sound- 

 post was present, but it was not until the lower part of the clamp 

 was in contact with the back that the normal character of the 

 tone was fully restored. A similar effect to that resulting from the 

 pressing of one end of the clamp only was produced by firmly placing* 

 one end of a wooden rod at this part of the belly. This effect may 

 be due to the setting-up in the belly, by pressure at this part, of 

 the peculiar nodal arrangement which the post produces when in its 

 place.* 



* According to Daguin some similar experiments were made by Savart, but I have 

 failed to find them in those of his papers to which I hare had access. 



" On pent la (Fame) mettre en dehors, en l'appuyant a une espece d' arcade dont 



on colle les pieds de chaque cote du violin On peut la remplacer par la 



pression d'un poicls cony enable appuye sur la table superieure." " Savart a conclu 

 de la qne l'ame a pour effet de rendre normales les vibrations de la table. . . ." 

 " Traite de Physique," tome I, p. 575. 



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