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sounds ; it is only the high notes which affect it. If the strings 
of a violin be struck, the grave notes produce no alteration, 
whilst the highest ones violently urge it down. Hence, if a tune 
be played on a musical instrument, the flame, variously affected 
by the different notes, dances in perfect time to the music. Still 
more striking is this action when a musical snuff-box is set 
going, and placed near the flame. Indeed, so very magical is 
the unseen connection between the instrument and the flame, 
that at first sight the experiment seems more appropriate for a 
conjuror’s stage than a scientific lecture table : but are not the 
experiments of the philosopher always more wonderful than the 
tricks of the conjuror? 
In the same way that the flame responds to certain notes of 
musical instruments, so it picks out, and is more or less moved 
by various vocal sounds. Eepeating, in the same pitch, the 
vowels to the flame, it will be seen that the sound of u cannot stir 
the flame, whilst e affects it powerfully, and ak still more ener- 
getically. The cause of this is found in the fact, that in the latter 
sounds there are present higher tones which are absent in the 
first, and it is to these over-tones, or harmonics, of the funda- 
mental note common to all the vowel sounds, that the agitation 
of the flame was due. If, therefore, we address the flame, it 
curtsies, bobs, and bows, or remains unmoved, just as the words 
we utter may happen to contain more or less, or none of those 
high notes, to which this flame is peculiarly sensitive. 
Hence the reason why the flame is so intensely agitated by a 
noise. For this unmusical sound is caused by an admixture of 
various notes, and among them, especially if the noise be of a 
certain class, are sure to be found a few of those notes which 
most largely influence the flame. The sound of the gentlest 
tap, the chinking of money, the creaking of boots, the crackling 
of a fire, the dropping of a cinder, and even the splashing of a 
rain drop and the ticking of a watch, all startle or convulse the 
flame. Whilst the crumpling of tracing paper, or the rustling 
of a silk dress, sets it frantic with commotion. 
What, let us now ask, is the explanation of these remarkable 
phenomena ? {Seeking to know the cause of what I had observed, 
I was led to notice last summer, that an increased pressure of 
the gas acted precisely like a shrill sound in shortening the flame. 
Dr. Leconte has, however, the prior claim to this observation, 
which has been raised by Professor Tyndall to an explanation 
of the phenomenon, given in the following words : — “ The gas 
issues from its burner with a hiss, and an external sound of 
this character added to that of a gas-jet already on the point of 
roaring, is equivalent to an augmentation of pressure on the 
issuing stream of gas.” # This statement holds good for all 
* Philosophical Magazine } February 1807, p. 99. 
