Sound / by John Tyndall.

  • Tyndall, John, 1820-1893.
Date:
1883
Catalogue details

Licence: Public Domain Mark

Credit: Sound / by John Tyndall. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    that the explanation given by Prof. Faraday in 1818 is essentially correct. It is well known that he referred these sounds to the successive explosions produced by the periodic combination of the atmospheric oxygen with the issuing jet of gas. While reading Prof. J. Plateau's admirable researches (third series) on the ' Theory of the Modifications experienced by Jets of Liquid issuing from Circular Orifices when exposed to the Influence of Vibratory Motions,' 1 the idea flashed across my mind, that the phenomenon which had fallen under my observation was nothing more than a particular case of the effects of sounds on all kinds of fluid jets. Subsequent reflection has only served to fortify this first impression. The beautiful investigations of Felix Savart on the influence of sounds on jets of water, afford results presenting so many points of analogy with their effects on the jet of burning gas, that it may be well to inquire whether both of them may be referred to a common cause. In order to place this in a striking light, I shall subjoin some of the results of Savart's experiments. Vertically descending jets of water receive the following modifi- cations under the influence of vibrations :— 1. The continuous portion becomes shortened; the vein resolves itself into separate drops nearer the orifice than when not under the influence of vibrations. 2. Each of the masses, as they detach themselves from the extremity of the continuous part, becomes flattened alternately in a vertical and horizontal direction, presenting to the eye, under the influence of their translatory motion, regularly dis- posed series of maxima and minima of thickness, or ventral segments and nodes. 3. The foregoing modifications become much more developed and regular when a note, in unison with that which would be produced by the shock of the discontinuous part of the jet against a stretched membrane, is sounded in its neighbourhood. The continuous part becomes considerably shortened, and the ventral segments are enlarged. 4. When the note of the instrument is almost in unison, the continuous part of the jet is alternately lengthened and shortened, and the beats which coincide with these variations in length can be recognised by the ear. 1 Phil. May. S. 4, vol. xiv. p. 1, et scq., July 1857.