644 On theMethod of judging by the Ear 
the face, which defect renders them incapable of 
perceiving the impulses of feeble sounds. . 
The faculty of hearing which I have been ine 
vestigating, betrays men under certain circum- 
stances into errors, that appear the more surpriz- 
ing, because the judgment relies on the admo- 
nition of the ears with the greatest confidence, 
The theory. of these deceptions will therefore 
form a proper supplement to this essay, Men- 
tion has been already made of the sudden change 
that takes place in the sensible direction of a 
sound, as soon as the direct communication with 
the sounding body happens to be broken by the in- 
tervention of a lofty obstaele, provided the sound 
in question be loud enough to produce an echo 
from anather quarter. .Any person who has had 
occasion to walk along a valley obstructed with 
buildings, at the time that a peal of bells was 
ringing in it, will assent to the truth of the cir~ 
cumstance here alluded to. For the sound of 
the bells instead of arriving constantly, at the ears 
“of a person so situated, in its true direction, is 
frequently reflected in a short time from two or 
three different places. These deceptions are in 
many cases so much diversified by the successive 
interpositions of fresh objects, that the steeple 
appears, in the hearer’s judgment, to perform the 
part of an expert venirifoguist on a theatre, the 
