Theory, of Compound Sounds. 663° 
The first time I perused Dr. Smith’s Har- 
monics, Dr. Young’s objection occurred to me; 
but the preceding train of arguments removed 
the scruple, without discovering, the author’s rea-. 
sons for treating this article of his work with so 
much brevity.. Perhaps the demonstration, which 
cost me an effort of study, was an intuitive con- 
clusion in his comprehensive mind. As soon as 
the proposition was established, I assented to his. 
definition of an interval of sound, allowing it to 
be a quantity of a certain kind, terminated by a. 
graver and an acuter sound, The demonstration 
of Prop. V. convinced me, that intervals of this 
sort may be subdivided by the interposition 
of one or more intermediate sounds, which con- 
cession formed the basis of my analysis of the 
hhuman voice.* Speculative men may differ in. 
opinion about the origin of the small intervals 
which form the tones of various voices; but they 
must exist, whether we ascribe them to an un- 
dulating motion like that of a stretched cord, or 
to the cotemporary vibrations of a system of elas- 
tic bodies. It does not appear, that Dr. Young 
was acquainted with my paper at the time, he 
composed his own; but he found it necessary to 
allow the tone of the larynx to receive various 
‘modifications from the vibrations of the adjacent 
VOL. V. x X 
* Page 58, 
