334 



clifFerent lengtlis, and a short organ pipe, for producing the exter- 

 nal sounds. 



In studying experimentally the conditions under which these 

 sounds are produced, Prof". Rogers had lately ascertained that the 

 usual absence of the sonorous effect in the case of lamps or can- 

 dles burned under the same conditions as the gas, is not due, as 

 might be supposed, to a mechanical interference of the wick with 

 the vibrating motion. He found that wicks of cotton thread and 

 of asbestus, introduced into a jet pipe of gas, even so as to' pro- 

 ject far into the flame, did not prevent its singing, although they 

 impaired the purity of the musical tone. The difficulty of ob- 

 taining continuous musical sounds from a common flame with a 

 wick, must rather be ascribed to the nature of the combustible 

 matter, which, requiring a very large supply of air to produce 

 the explosions, is liable to be extinguished before the musical 

 sound is developed. 



To obtain an Ethe7' Jlame suitable for these experiments. Prof. 

 Rogers uses a glass tube about eight inches long and one quarter 

 of an inch in diameter, open below and drawn somewhat bluntly 

 to a point, with a small aperture at the top ; some loose cotton 

 twine or thread of Asbestus being introduced so as to terminate 

 at or very near the pointed opening, the tube is half filled Avith 

 sulphuric ether ; the larger end is closed wath a tight cork, and 

 the little ether candle is fixed vertically in the centre of a wooden 

 block. On applying a light to the apex, the ethereal vapor burns 

 in a steady bluish jet, which with proper tubes enables us readily 

 to repeat all the experiments on the singing and the silent flame. 

 This simple apparatus acts freely at ordinary temperatures, and 

 may be used from time to time for several days without replen- 

 ishing. 



In regard to the agency of the flame in giving rise to the musi- 

 cal tone. Prof Rogers thought it might be compared to that of 

 the reed of various wind instruments, the vibration of which, 

 "by giving motion to the column of air in the pipe, causes the 

 sound to begin, although the vibrating column, by its reaction on 

 the reed, controls more or less the rate of its oscillations, and de- 

 termines the pitch of the sound produced. A similar reaction 

 between the aerial column and the flame quickly establishes a 

 synchronous motion of the two, corresponding to the fundamental 

 note, or to one of the natural harmonics of the tube. 



