Experimenif and Inquirtet refpeBirtg Sound and Light, 



77 



Table vrii. 



Diameter of the tube .1. A, B, C, and D, as in Table vii. 



Tabh 



e IX. 



Table X, 



Diameter 



of the 



tube .3. 



A,B,C, 



and D, as 



in Table 



VII. 



A is the preflure. 

 B, the diftance of 

 the apex of the 

 cone from the orI» 

 fice of a tube , r 

 in diameter. 



III. Ocular Evidence of the Nature of Sound. 

 A tube about the tenth of an inch in diameter, with a lateral orifice half an Inch from 

 its end, filed rather deeper than the axis of the tube, Fig. 27, was inferted at the apex of a 

 conical cavity containing about twenty cubic inches pf air, and luted perfeftly tight: by 

 blowing through the tube, a found nearly in unifon with the tenor C was produced; fi-y 

 gradually increafing the capacity of the cavity as far as feveral gallons, with the fame 

 mouth-piece, the found, although faint, became more and more grave, till it was no bn^ 

 ger a mufical note. Even before this period a kind of trembling was diftinguifliable ; and 

 this, as the cavity was ftill further increafed, was changed into a fucceffion of diftinft 

 -puffs, like the found produced by an explofion of air from the lips; as flow, in fome in- 

 fiances, as 4 or 3 in a fecond. Thsfe were undoubtedly the fingle vibrations, which, 

 when repeated with fufficient frequency, imprefs on the auditory nerve the fenfation of a. 

 continued found, On forcing a current of fmoke through the tube, the vibratory motion 



of. 



