( 524 ) 
A mute placed on the bridge damps both motions. But from the 
fact that it renders the sound mellower we think we may infer 
that the b’s are reduced by it by a higher fraction than the a’s. 
This would mean that the transverse motion of the bridge is 
damped to a higher degree by putting on the mute than the paral¬ 
lel motion. 
5. We have also tried to show experimentally that the bridge 
in its parallel motion turns principally about its right foot. 
For this purpose we screwed two metal rings into the clamp of 
fig. 9, which were placed in a horizontal position. The violin was 
fitted with a steel string, as before moved electromagnetically. While 
the string was moving a small leaden ball was placed alternately in 
the two rings; the two balls weighed 34 grms each. They were 
attached to a thin cord; as nearly as ppssible at the same moment 
that one ball was lifted out, the second ball was carefully placed 
in the other ring. We expected that the sound of the violin would 
be perceptibly weakened as the ball on the right was removed and 
the left ball simultaneously put in. But we did not succeed in 
arriving at a trustworthy result in this manner; in the first place a 
rattling noise was sometimes apparent while the balls were being 
exchanged and in the second place the tone of the steel string was 
not always of the same intensity. 
6. The conclusion therefore to be derived from our experiments 
is that the bridge of a violin performs a parallel as well as a trans¬ 
verse motion and that the timbre of the tone, given by the violin, 
is modified greatly when the intensity of one of the motions is 
altered while leaving the other motion unchanged as nearly as possible. 
Herewith we have at the same time given the physical explanation 
of the action of the mute and also of the influence which the use 
of too thick or too thin a bridge has on the sound of a violin. 
The action of the mute is commonly described by calling it “dam¬ 
ping or “deadening” *). But if the mute caused nothing but a general 
damping or reducing of the bridge motion, the mute would only weaken 
the sound, and the same effect would be obtained by bowing softly on 
a violin without as by bowing hard on a violin with a mute. That 
however is by no means the case as every one knows. 
Delft, November 1909. 
i) Barton. “Textbook on sound”, p. 419: “The mute is a small apparatus 
of wood or metal which fits on the bridge, and thus deadens the sound considerably” 
