The Democratic advocate. [volume] (Westminster, Md.) 1865-1972, 1882-05-13
Our @lio.
Remarkable Echoes.
The Acoustic Qualities of the Old Hall
OF Representatives at the Capitol

Remarkable Echoes.
The Acoustic Qualities Of the Old Hall
Of Representatives at the Capitol
! Most of us are familiar with the famous
paddy Blake Echo" of Old Ireland, which,
in response to the query How are you?
replies, Every well, thank you. To the
doubling mind this may present an aspect
of incredulity; yet there are comparatively
few of the many hundred whose feet daily
tread the old Hall of Representatives who
are aware of the remarkable acoustic quail
ties possessed by that apartment. There
has been somewhat of a ghastly attempt
made to turn this place into hall of stat
uary, but it has not thriven. To the casu-
al observer it too forcibly suggests Madam
Tussands collection in the chamber of
Horrors, and they hurry through with only
glimpse at the uncanny form serving but
to render desolation more desolate.
Rouse your courage sufficiently to pass
through this row of solemn, blank-eyed
figures, get behind them and, turning your
| face to the marble slab of the arch, speak
in an ordinary tone The guide or one of
your party having previously placed him
self on the opposite side, you can then with
ease carry ON the most private conversation
without fear Of being overheard by the
crowd passing and repassing through the
body of the ROOM A whisper even can be
distinctly heard. This seems certainly Gu
rious; for naturally one would suppose, no
matter how great the echo, sound so
slight would be lost amid the buzz of con-
versation. laughs and Gathering of foot
steps over the stones. Yet, so perfectly is it
preserved, the voice even of different per-
sons can be distinguished, and oneinvolun-
/ tarily turns in expectation Of being the vic
tim of practical joke.
All scientists are agreed that sound Is
produced by vibrating motions impressed
upon atmospheric air Whatever the agent
whose undula,ions produce light and heat,
that motion is capable of reflection. If,
then an agent.so subtle can suffer such an
/ impediment to motion. it is not singular
that one Of whose existence We have almost
tangible evidence should be acted upon
in the same manner.
4 We deduce, moreover, from our knowl-
edge Of the origin Of sound, the fact that
reflection win be produced whenever 1t
meets with hard, plain surface. This
rests upon no argument; we have evidence
of ii in that remarkable phenomenon called
echo.
Some substances We know absorb sound,
some transmit. while Others again reflect,
and. as is the case with light. all these ef-
fects may be produced By the same sub
stance. The sound of piano, for instance,
Is reflected from all sides Of the room, yet
part Is evidently transmitted, as the
sound heard outside Is not 50 great as that
heard at an equal distance in the room: a
Z portion, therefore, Is absorbed.
Sound travels with such velocity that
even when it meets with plain surface Of
sufficient extent, favorably situated, the
Original sound and echo are frequently
/ blended. Instances are numerous IN which
/ the echo is several time suecessiyely repeat
ed. In the same hall, with the speaking
columns or Whispering stones, as they are
yariously called, is an example Of this.
One Of the many squares Of marble eou-
posing the floor possesses this curious
power. Stand upon it, speaking in an or
dinary tone, and you viii not hear your own
voiee-that is lost, swallowed up in the
( dozen fcndish reverberations which thun-
der in your ear the words You are conscious
Of having spoken, yet which seemed at the
time to make no impression upon the waves
Of sound. The feeling is any but pleas
ant one, to know you have spoken without
catching the reflection Of your own voice,
and 10 a person Of nervous temperament
the effect is the reverse Of agreeable.
This Is, however, easily accounted for By
the fact that two or more substances Iaay
/ be 50 placed that sound reflected by one
shall be returned BY another, until it flies
away altogether.
II may not be generally known that
sounds are more readily reflected by night
than by day. In Woodstock Park, mean
7 Oxford, there Is an echo which repeats
seventeen times BY day and twenty by
night. Attaching to this exists roman
l tic superstition; for il was here that Henry
I III, goaded By tormenting uncongenIal
wife. hid his love, Rosamond. Hid her
only TO be discovered and put to death by
/ the jealous Eleanor. To the surrounding
country folk this echo represents the dis
embodied spirit of the unhappy captive.
The reason given for a sound being
more often repeated by night than by day,
saws an old writer, us because the air be
ing colder at that time, is more dense, and
therefore the return Of the first vibrations
being slower, gives time for the repetition
of more syllables." This explanation is a
curious. aud we can hardly imagine salts
factory, one for the phenomenon. hwould
seem better accounted for by the fact OF
the density being more uniform at night
than during the day, and the intensity Of
sound consequently suffering less rapid
decay.
Barthius states ON his own authority that
on the banks of the Waha, between Coblen-
ton and Bingen, is an echo which not only
repeats seventeen times. as in this former
case, but does so with surprising varieties
Whereas in ordinary cases the repetition is
not heard until after the words are spoken
in this the voice is scarcely heard at all
the echo sounding sometimes near, at Others
farther off; sometimes quite distinctly, at
others not at ALL One person detects ono
voice, another several; one catches the echo
from the right, another from the left.
Beneath the Menai suspension bridge
separating the Isle of Anglesy from Wales
close to one of the main piers Is a remark
ably fine echo, upon which an experiment
was made BY Sir John Hersehel and Mr.
Babbage, leading to the conclusion that iii
the reflection of sound there is an evident
approach to the law Ofequality between tn.
angles of incidence and reflection, which
obtains in that of light, and tendency in
the reflected sound to confine itself to the
directions which a ray of light regularly
reflected at the echoing surface would fol
low, and to spread into the surrounding an
equally in all directions,
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