‘ 
Theory of Compound Sounds, ‘665 
cause the pitch of it may be varied. for the first 
sounds proceeding from the action of the file, 
evidently supply nothing but the tone, Many 
instances of the kind occur in art and nature: 
the notes of all reed-instruments are of this de- 
scription, and the voice must be referred to the 
same class, because the larynx resembles a reed- 
instrument in structure, 
