NATURAL PHILOSOPHY. 185 



several other gases and vapors. He was, moreover, the first to give a philo- 

 sophical theory of the sound, by showing that, in the conditions of the 

 experiment, the flame resolved itself into a series of little explosions, which, 

 succeeding each other at very small and equal intervals of time, gave rise to 

 regular, and therefore musical vibrations in the tube. In the recent experi- 

 ments the further fact has been observed, that the flame, both when singing 

 and when silent in the tube, is strongly acted on by external sounds, having 

 a certain musical relation to the tone of the pipe or flame. 



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 candles burned under the same con- 

 ditions as the gas, is not due, as might be supposed, to a mechanical inter- 

 ference of the wick with a vibrating motion. He found that wicks of cotton 

 thread, and of asbestus, introduced into a jet-pipe of gas, even so as to project 

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

 purity of the musical tone. The difficulty of obtaining 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 ether flame 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 draAvn 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 

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

 ether candle is fixed vertically in the centre of a wooden block. On apply- 

 ing 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 

 replenishing. 



In regard to the agency of the flame in giving rise to the musical 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 determines 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. 



At a subsequent meeting, Prof. Rogers stated that by employing hollow 

 circular wicks and using tubes but slightly exceeding them in diameter, he had 

 been able to produce these musical effects with the flames of sulphuric ether, 

 common alcohol, and the mixture of the latter with spirits of turpentine, 

 which is known as burning-fluid. By using an iron tube at a high tempera- 

 ture he had obtained, though less perfectly, a similar result with the flame of 

 spermaceti oil. 



As the effect in these experiments depends on the access to the flame of a 

 current of air of definite amount and velocity, and in a proper direction, it is 

 necessary to adjust the diameter of the wick and size of the flame to the 

 dimensions of the tube employed, and to hold the tube with its lower edge a 



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