Books › On the Function of the Sound-Post and on the Proportional Thickness of the Strings of the Violin, 1883 › scan 3
Scan 3
On the Function of the Sound-Post and on the Proportional Thickness of the Strings of the Violin, 1883
8 lines. Read by computer on 18 September 2026. No printed page number was found. See the scan on archive.org.
1There could be no doubt that vibrations were carried by the clamp, for the lower end was powerfully agitated when the upper end rested upon the belly. If the sole function of the sound-post is to serve as a firm prop for the foot of the bridge, it should fulfil this condition most fully when placed under the foot of the bridge. In this position of the sound-post, however, as is well known, the tone is much injured.
3In order to separate that part of the function of the sound-post which serves as a support from the further function it may possess as a transmitter of vibrations, it was desirable to introduce such alterations in the structure of the sound-post as would enable it to retain its supporting power, and yet greatly modify and, if possible, stop its power of transmitting vibrations. A sound-post was made in which about half an inch of the middle was cut out, and a piece of lead inserted, also a sound-post in which instead of lead sealing-wax was put in. The effect of these compound posts, which retained uninjured their prop power, was to modify greatly the quality of the tone, but not to diminish its quantity in any marked degree, a result in favour of the view that the character of the wood of which the post is made does influence the tone, and that vibration is transmitted by the post. As these compound posts could transmit vibrations freely, it was desirable to contrive a post which would not carry vibrations and yet form a firm prop. A post was made with a piece of hard India-rubber inserted in the middle, but this post was found by experiment with a tuning-fork to transmit vibrations to some extent. Other materials were tried without success. A post capped at each end with pieces of sheet vulcanized rubber stopped almost completely the sound of a tuning-fork when the foot of the fork rested on the rubber over one end of the post, while the other end equally protected with rubber rested on a body capable of reinforcing the sound of the fork. This rubber-capped post was firmly fixed in position in the violin, so that it would be able to support fairly well the belly and foot of the bridge, and yet not be able to carry vibrations; unfortunately it does not seem possible, from the nature of things, to have a rigid prop which does not transmit vibrations, but this post with thin sheet rubber at the ends firmly forced into position, must have been fairly efficient in its supporting power. The effect on the tone was about the same as when the sound-post was removed. When the wooden clamp was put on, then the normal tone returned, and the back vibrated strongly.
5These experiments appear to show that the sound-post is more than a prop, and that besides its other functions, it does transmit vibrations to the back in addition to those which are conveyed through the sides.
7Experiments with sand and the touch-rod appear to me to show that Helmholtz's statement is too absolute when he says "it is only
The computer misreads some letters and numbers. Where a name matters to you, read the scan.