of the Position of Sonorous Bodies. 645 
extent of which is adapted to its own powers, 
and not to those of the human voice. 
The phenomenon has often attracted my 
attention ; and the similarity of effect which 
connects it with ventriloquism, convinces me 
every time I hear it, that what we know to 
be the cause in one instance is also the cause in 
the other: I mean that the echo reaches the ear, 
while the ‘original sound is intercepted by ‘acci- 
dent in the case of the bells, but by aré in the 
case of the ventriloquist. In order that the 
cause which gives rise to the amusing tricks of 
this uncommon talent may be pointed out with 
the greater clearness, it will be proper to describe 
certain circumstances that take! place in the act 
of speaking, because the skill of the ventrilo- 
quist seems to consist in a peculiar management 
of them. Articulation is the art of modifying 
the sound of the larynx, by the assistance of the 
cavity of the mouth, the tongue, teeth, and lips. 
The different vibrations, which are excited by 
the joint operation of the several organs in 
action, pass along the bones and cartilages, 
from the parts in motion to the external tegu- 
ments of the head, face, neck, and chest; from 
which, a succession of similar vibrations is im- 
parted to the contiguous air, thereby converting 
the superior moiety of the speaker’s body into an | 
extensive seat of sound, contrary to general 
opinion, which supposes the passage of the voice 
