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MR. C. A. BELL ON THE SYMPATHETIC VIBRATIONS OF JETS. 
In 1866 Kundt'"' obtained musical tones by the impact of two flames, or of an air- 
jet against a flame. He considered it a desirable condition that the flame and jet 
orifices should be of unequal size. 
Leconte in 1858, and Barrett in 1867, discovered the now well-known “ sensitive 
flame,” which was investigated by Barrett and Tyndall.! In order to detect 
possible changes behind the orifice, which might account for the phenomenon, these 
physicists mixed smoke with the gas previous to ignition. No such changes were 
discovered ; but they were thus led to observe that jets of unignited gas and air 
are also changed in form by sound, a fact strangely overlooked by Sondhauss. The 
changes occurring in such jets were found to be very similar to those induced by 
sound in liquid jets. Barrett and Tyndall stated that an ignited jet of gas—a 
dame—is sensitive to higher tones than an unignited jet at the same pressure, and 
that the effective tones are higher the smaller the orifice. They attributed the 
phenomenon to the resonance of the gas in the connecting tube. 
In the course of these experiments it was noted that a sensitive flame sometimes 
reproduces the tone by which it is affected. 
About this time also, Tyndall| produced a new kind of “ sensitive flame ” by 
blowing a jet of air through a gas flame : and observed that the ordinary blowpipe 
flame could be brought into a sensitive condition. Tyndall considered that the tones 
which visibly affect a sensitive flame must be of about the same pitch as those 
produced by friction of the gas against the orifice. 
In a subsequent note Barrett§ compared a flame at different pressures to a series 
of tuned reeds. He also made the interesting discovery that sensitive flames may be 
violently affected by vibrations far beyond the limit of audition. 
In 1875 Decharme|| not only produced tones by directing a jet of air against the 
surface of mercury, but observed that the latter was thereby thrown into vibration, as 
proved by the motions of a beam of light reflected from it. 
The same experimenter also obtained musical tones by blowing air through a tube 
against a flame. Carbonic acid and pure oxygen, used instead of air, gave but feeble 
effects, and nitrogen hardly any. He attributed the action of carbonic acid to its 
decomposition by the flame. 
More recently NeyreneufIT has studied the phenomena of jets and flames. He 
observed that the “ nappe ” formed by the meeting of two flames, or of an air-jet and 
a flame, not only responded to, but also reproduced a limited range of tones uttered 
* Poggend. Ann at, vol. 128 (1866), p. 610. 
f Phil. Mag., ser. 4, vol. 33 (1867), pp. 92, 211, 287. 
J Phil. Mag., ser. 4, vol. 33 (1867), p. 375. 
§ Nature, vol. 16 (1877), p. 12. 
|| Poggend. Anna!., Ergzgsb. 7 (1876), p. 176; Comptes Rendus, vol. 80 (1875), p. 1602, and vol. 81 
(1875), p. 339; Phil. Mag, ser. 4, vol. 50 (1875), p. 496. 
ll Annal. de Chimie, ser. 5, vol. 25 (1882), p. 183. 
