Vibrations on Gaseous and Liquid Jets. 



383 



Fiff. 15. 



flame picks certain sounds from my utter- Fig. 14. 

 ance ; it notices some by the slighest nod, to 

 others it bows more distinctly; to some its 

 obeisance is very profound, while to many 

 sounds it turns an entirely deaf ear. 



In fig. 14 this brilliant flame is shown, tall 

 and straight. On chirruping to it, or on 

 shaking a bunch of keys within a few yards 

 of it, it falls to the size shown in fig. 15, the 

 whole length a b of the flame being suddenly 

 abolished. The light at the same time is 

 practically destroyed, a pale and almost non- 

 luminous residue of the flame alone remaining. 

 These figures are taken from photographs of 

 the flame. 



In our experiments down stairs we have 

 called this the "vowel flame," because the differ- 

 ent vowel-sounds affect it differently. We have 

 already learned how these sounds are formed — 

 that they differ from each other through the 

 admixture of higher tones with the funda- 

 mental one. It is to these tones, and not to 

 the fundamental one, that our flame is sensi- 

 tive. 1 utter a loud and sonorous u, the flame 

 remains steady ; I change the sound to o, the 

 flame quivers; I sound e, and now the flame 

 is strongly affected. I utter the words boot, 

 boat, and beat in succession. To the first there 

 is no response ; to the second the flame starts; 

 but by the third it is thrown into greater com- 

 motion; the sound Ah! is still more powerful. 

 Did we not know the constitution of vowel- 

 sounds, this deportment would be an insoluble 

 enigma. As it is, however, the flame is a de- 

 monstrator of the theory of vowel-sounds. It 

 is most sensitive to sounds of high pitch ; 

 hence we should infer that the sound Ah! contains higher notes 

 than the sound e, that e contains higher notes than o, and o 

 higher notes than u. I need not say that this agrees perfectly 

 with the analysis of Helmholtz. 



This flame is peculiarly sensitive to the utterance of the letter 

 s. If the most distant person in the room were to favour me 

 with a " hiss," the flame would instantly sympathize with him. 

 A hiss contains the elements that most forcibly affect this flame. 

 The gas issues from its burner with a hiss, and an external 

 sound of this character is therefore exceedingly effective. I 



