Dr. R. Konig on Manometric Flames. 113 



with a resonator an open organ-pipe of not too great diameter, 

 during the interference of the waves of the fundamental the 

 vibrations of the octave become again prominent. By interference 

 we can remove not only the fundamental, but any overtone we 

 please from a sound, as may be clearly demonstrated with the 

 above-described covered pipe. I conduct the sound into the 

 apparatus, while I connect with it, after the removal of the gas- 

 burner, the capsule at the end by means of an india-rubber tube. 

 If I then draw out the one tube so far that interference ensues 

 for note 3, the centre flame in the mirror shows the simple 

 flame-series of the fundamental, while the two others form the 

 picture before described (fig. 5, PI. I.), resulting from the com- 

 bination of notes 1 and 3. In the same way we can banish 

 from vowel-sounds various overtones, or rather whole series of 

 them, which offers a new and fruitful method for the investiga- 

 tion. In these experiments the arrangement with three flames 

 is particularly useful, because the upper and lower flames remain- 

 ing always unchanged permits the slightest alteration in the 

 middle one to be observed. Thus, for example, the vowel U 

 sung on c into the apparatus shows the fundamental only weakly, 

 accompanied by the octave. If we place the apparatus so that 



the w r aves of c interfere, every trace of this octave is lost, whereas 

 on the interference of the fundamental two narrow flames of 

 almost equal height take the place of each wide flame ; these 

 narrow flames represent the octave, now almost alone. With 

 sung on the same note (when the fundamental is accompanied 

 much more strongly by the octave than with U) we can make 

 the same experiments ; only here at the interference of the octave 

 the note 3 becomes prominent, whilst the wide flame of the fun- 

 damental spreads out into three diminishing summits. A sung 

 on c, at the interference of the third note brings forward strongly 

 the octave with the fundamental. If the waves of the octave 

 interfere, there appears a group of five flame-summits, which 

 appear to indicate the notes 1, 3, and 5. If we suppress the fun- 

 damental and with it the notes 3, 5, &c, there appears a simple 

 flame-series, which is formed by the octave alone. 



These phenomena are nevertheless not always of so simple a 

 nature as in these examples, when it is a question of more com- 

 posite flame-groups of the deeper sounds ; and therefore I will 

 now call attention to the fact that, on lengthening one of the 

 tubes of the apparatus, we often see suddenly very great changes 

 in the flame-picture when the former is between the interference- 

 points of two successive overtones of the sound. This is then the 

 interference-point of the lower octave, or twelfth of a higher 

 overtone of the sound, which is in this way removed. 



Phil. Mag. S. 4. Vol. 45. No. 298. Feb. 1873. I 



