of the Position of Sonerous Bodies. 649 
echo he chuses in the place of it. But the su- 
perior part of the human body has been already 
proved to form an extensive seat of sound, from 
every point of which the two pulses are repelled, 
as if they diverged from acommon centre. This 
is the reason why people, who speak in the usual 
way, cannot conceal the direction of their voices, 
which in reality fly off towards all points at the 
same instant. The ventriloquist therefore, by 
some means or other, acquires the difficult habit 
of contracting the field of sound within the com- 
pass of his lips, which enables him to confine 
the reab path of his voice to narrow limits. For 
he, who is master of the art, has nothing to do 
but to place his mouth obliquely to the company; 
and to dart his words, if I may use the expres- 
sion, against an opposing object, whence they 
will be reflected immediately, so as to strike the 
ears of the audience from an unexpected quarter, 
in consequence of which the reflector will ap- 
pear to be the speaker. Nature seems to fix no 
bounds to this kind of deceptions, only care must 
be taken not to let the path of the direct pulses 
pass too near the head of the person who is to be 
played upon; for, if a line joining the exhibitor’s 
mouth and the reflecting body approach one of 
his ears too nearly, the divergency of the pulses 
will make him perceive the voice itself instead 
of the reverberated sound. 
