18G ANNUAL OF SCIENTIFIC DISCOVERT. 



little below that of the wick. The flame will then be seen to contract, to lose 

 much of its brilliancy, and, after more or less of a rattling sound, to give 

 forth a musical tone, which, with a little care, may be rendered quite smooth 

 and continuous. 



These results are readily obtained with the flame of the small circular wick 

 lamp now in use for burning the mixture of alcohol and turpentine. In this 

 form of lamp the wick-tubes rise about two inches above the reservoir, and 

 an internal movable tube is provided, which, being raised or lowered, serves 

 to vary the depth of the wick and to adjust the flame with great nicety. The 

 body of the lamp should be removed from its pedestal, and placed on a 

 ring support, to secure a free current of air upward through the central wick- 

 tube. 



A simple Avay of making the experiment with an alcohol wick, is to enclose 

 between two glass tubes a strip of cotton cloth or thick paper, so that it may 

 project a little beyond the upper end of the tubes. When charged with alco- 

 hol and lighted, it will furnish a hollow circular flame well suited for the 

 temporary production of the musical effect. 



These results favor the conclusion that flames of every kind are capable of 

 exciting sonorous vibrations, provided the air and combustible vapors are 

 brought together in such proportions as to form more or less of an explosive 

 mixture, and they therefore confirm the explanation of Faraday, which 

 refers the musical sounds produced in such cases to a rapid and iiniform suc- 

 cession of small explosions. 



The following experiments illustrate, in a very simple way, the origin and 

 some of the conditions of these musical vibrations : 



(1.) When a jet of burning coal-gas is introduced into the resonant tube 

 in a position in which it docs not sing spontaneously, we may cause it to 

 commence its musical performance by simply vibrating the jet-pipe rapidly 

 from side to side. In this experiment the pipe should be covered with soft 

 buckskin for two or three inches near its upper end, to prevent the sharp 

 jarring sound caused by its striking the glass. This movement of the jet is 

 so efficient in bringing on the sonorous state, that it will compel the flame 

 to sing, even in a tube in which it would not do so spontaneously in any 

 position in which we could place it. Indeed, it will often excite the musical 

 vibrations in cases where, from the unsuitable proportions between the tube 

 and flame, the external sounds used in Tyndal's experiment entirely fail to 

 bring on the sonorous state. 



Although the singing is induced more promptly when we allow the jet- 

 pipe in its vibrations to strike the sides of the tube, this action is not at all 

 necessary ; for we obtain the same result when the pipe is merely shaken to 

 and fro within such limits as to prevent its touching the glass. The effect 

 here described can hardly fail, when first observed, to excite surprise, espe- 

 cially if from previous trials we have found that the flame refuses either to 

 sing spontaneously or under the action of external sound. 



So far as the impulse of the jet-pipe against the sides of the tube is influ- 

 ential in exciting the sound, we must ascribe its action to the feeble musical 

 resonance produced by it within the tube, which, although composed of 

 several sounds, may always be observed to include the fundamental note of 

 the tube. This action is therefore like that of a unison note sounded by the 

 voice or an external instrument, or that of any other mechanical agency 

 giving rise to a vibration of the included column of air. But the other and 

 far more remarkable effect, the excitement of the musical condition in the 



