112 Additional Notes. 



organ-pipe about two thirds of it are believed to pass on the outside of 

 this edge, and one third to pass on the inside of it; but this current of 

 air on the inside forms an eddy, whether the bottom of the pipe be 

 closed or not; which eddy returns upwards, and strikes by quick in- 

 tervals against the original stream of air, as it falls on the edge of the 

 aperture, and forces outwards this current of air with quick repetitions, 

 so as to make more than t\vo thirds of it, and less than two thirds al- 

 ternately pass on the outside; whence a part of this stream of air, on 

 each side of the edge of the aperture is perpetually stopped by that 

 edge; and thus a vacuum and vibration in consequence, are recipro- 

 cally produced on each side of the edge of the aperture. 



The quickness or slowness of these vibrations constitute the higher 

 and lower notes of music, but they all of them are propagated to dis- 

 tant places in the same time; as the low notes of a distant ring of 

 bells are heard in equal times with the higher ones : hence in speak- 

 ing at a distance from the auditors, the clear sounds produced in the 

 larynx by the quick vibrations of its aperture, which form the vowels; 

 the tremulous sounds of the L. R. M. N. NG. which are owing to 

 vibrations of certain apertures of the mouth and nose, and are so slow, 

 that the intervals between them are perceived; the sibilant sounds, 

 which I suppose are occasioned by the air not rushing into a complete 

 vacuum, whence the vibrations produced are defect! vein velocity; and 

 lastly the very high notes made by the quickest vibrations of the lips 

 in whistling; are all heard in due succession without confusion; as 

 the progressive motions of all sounds I believe travel with equal velo- 

 city, notwithstanding the greater or less quickness of their vibrations. 



III. STRUCTURE or THE ALPHABET. 



Mute and antesonant Consonants, and nasal Liquids. 



P. If the lips be pressed close together and some air be condensed 

 in the mouth behind them, on opening the lips the mute con- 

 sonant P begins a syllable ; if the lips be closed suddenly during 

 the passage of a current of air through them, the air becomes 



