( 463 ) 
Sis, 
SOUNDS AND ECHOES. 
j. *lie P'’°Pagated successively from the soundincr body 
V- places which arc ’ ' 
'«ci 
^c. 
nearest to it, then to those more 
Every observer knows that when a gun is 
3 i* 'Considerable distance from liim, he perceives the 
and the 
^''te *-iioe before he hears the report j 
^ t)f j”g is true with respect to the stroke of a hammer, 
^'"11 a stone, or, in short, any visible 
(j. '"cli produces a sound or sounds. In general, 
^'’1(1 through the air at tlie rate of 1142 feet in a 
C* "’i*tli '^Icittoen miles in a minute. This is the 
^*as(, kinds of sounds, the softest whisper flying as 
|i .tctej^ i^odest thunder. Sound, like light, after it has been 
3t gj ‘pOtD several places, may be collected into one 
jjg ® tocus, where it will be more audible than in any 
on this principle wmispeeing galleries 
k.*}>6 1) relative to the celebrated whispering gallery 
A of St. Paul’s Church, London, will be com- 
6c description of that noble edifice. 
t) IS the reflection of sound striking against a sur- 
'tair'l^ht rt 'no renection ot sound striking against a sur- 
hill ll'c purpose, tts the side of a house, a brick 
ijf '"ct i,’ ®-'C- and returning back again to the ear, at 
time. If a person stand about sixty-five 
“tfl *Ptnk 1 ^ ® surface, and perpendicular to it, 
V^*6<1 h 1 ® ®ound will strike against the wall, and be 
V ^Saii, .> sothii^, he will hear it as it 
>ts return. 
Q'ctitig’ an 
M aU 
it goes to tlie wall. 
If a bell situated in the same way 
obsen’er stand betv'een the bell and the 
he will hear the sound going to the 
Lastly, if the sound strike the 
ilj *tjttdg • *’• "'’*1 gtt oft’ obliquely, sb tliat a person 
A *''^t 6 direct line between the bell and the wall 
»Sr> the echo. 
. the greater or less distance from the speaker, 
ij^Syllgg.'^'^ject will return the echo of several, or of 
of h! ’ syllables must be uttered before 
^yll^tile reaches tlie ear, to prevent the 
t“f sp ^‘oh would otherwise ensue. In a moderats 
about three and a half syllables axv 
