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L. On the Action of Sonorous Vibrations on Gaseous and Liquid 

 Jets. By Professor Tyndall, F.R.S. fyc. 



[With the permission of Professor Tyndall we print the fol- 

 lowing extract from the sixth lecture of his work on Sound, now 

 on the point of publication. A portion of the extract has already- 

 appeared in an abbreviated form in the Philosophical Magazine. 

 We have also to thank Professor Tyndall for the use of the 

 woodcuts which illustrate the paper. — : Ens.] 



IN a former lecture I referred to the oscillations of water in a 

 bottle as revealing the existence of vibrations of a definite 

 period in the general jar of a railway train. The fish-tail flames 

 in some of our metropolitan railway carriages are far more sen- 

 sitive acoustic reagents. If you pay the requisite attention, you 

 will find single flames here and there jumping in synchronism 

 with certain tremors of the train. A flame, for example, having 

 a horizontal edge when the train is still, will, during the motion, 

 periodically thrust forth a central tongue, and continue to jump 

 as long as a special set of vibrations is present. It will subside 

 when those vibrations disappear, and jump again when they are 

 restored. When the train is at rest, the tapping of the glass 

 shade which surrounds the flame rarely fails, when it is sensitive, 

 to cause it to jump. 



This action of sound upon a naked fish-tail flame was first ob- 

 served by Professor Leconte at a musical party in the United 

 States. His observation is thus described : — " Soon after the 

 music commenced, I observed that the flame exhibited pulsations 

 which were exactly synchronous with the audible beats. This 

 phenomenon was very striking to every one in the room, and espe- 

 cially so when the strong notes of the violoncello came in. It was 

 exceedingly interesting to observe how perfectly even the trills 

 of this instrument were reflected on the sheet of flame. A deaf 

 man might have seen the harmony. As the evening advanced, 

 and the diminished consumption of gas in the city increased the 

 pressure, the phenomenon became more conspicuous. The jump- 

 ing of the flame gradually increased, became somewhat irregular, 

 and finally it began to flare continuously, emitting the charac- 

 teristic sound indicating the escape of a greater amount of gas 

 than could be properly consumed. I then ascertained, by expe- 

 riment, that the phenomenon did not take place unless the dis- 

 charge of gas was so regulated that the flame approximated to 

 the condition of flaring. I likewise determined by experiment 

 that the effects were not produced by jarring or shaking the floor 

 and walls of the room by means of repeated concussions. Hence 

 it is obvious that the pulsations of the flame were not owing to 



