In the experiments of M. Schaffgotsch and Prof. J. Tyndall, it is evident that “the shaking of the singing-flame within the glass tube,” produced by the voice or the siren, was a phenomenon perfectly analogous to what took place under my observation _without the intervention of a tube_. In my case the discharge of gas was so regulated that there was a tendency in the flame to flare, or to emit a “_singing-sound_.” Under these circumstances, strong aërial pulsations occurring at _regular intervals_ were sufficient to develop synchronous fluctuations in the height of the flame. It is probable that the effects would be more striking when the tones of the musical instrument are _nearly_ in unison with the sounds which would be produced by the flame under the slight increase in the rapidity of discharge of gas required to manifest the phenomenon of flaring. This point might be submitted to an experimental test. As in Prof. Tyndall’s experiments on the jet of gas burning within a tube, clapping of the hands, shouting, etc., were ineffectual in converting the “silent” into the “singing-flame,” so, in the case under consideration, _irregular_ sounds did not produce any perceptible influence. It seems to be necessary that the impulses should _accumulate_, in order to exercise an appreciable effect. With regard to the mode in which the sounds are produced by the combustion of gases in tubes, it is universally admitted 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,”[84] 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 modifications under the influence of vibrations: 1. The continuous portions become shortened; the vein resolves itself into separate drops nearer the orifice than when _not_ under the influence of vibrations.