of the Position of Sonorous Bodies. 647 
any body near him hears two voices whilst his 
continues, but as soon as the noise ceases the 
echo is perceived. This does not happen because 
the one begins the moment the other ends; but 
the reflected sound being the weaker of the two, 
it is smothered by that which precedes it. 
We have seen in what manner secondary or 
teflected sounds are smothered by their princi- 
pals; but though the places of such sounds ares 
not recognized by the ear, their effects do not 
die away unnoticed: for the reverberated pulses 
mingle with those which come immediately from 
the sounding body, and thereby alter the sensa-~ 
tion, which, without their interference, would be 
less compounded. This is the reason why the 
same musical instrument has one tone in a close 
chamber, where its notes undergo a multi- 
plicity of reverberations, and another in the 
open air, where the reflections are few in com- 
Parison. ; 
But it is time to apply the preceding facts to 
the subject in hand; and it will be proper to begin 
with a familiar example. When an orator ad- 
dresses an audience in a lofty and spacious room, 
his voice is reflected from every point of the 
apartment, of which all present are made sen- 
sible by the confused noise that fills up every 
pause in his discourse; nevertheless every one 
VOL. V.. aa 
