The Wichita daily eagle. [volume] (Wichita, Kan.) 1890-1906, 1898-01-18
News Of Recent Science
ExPLANArIoN OF ECHOES.

! EXPLANATION OF ECHOES.
On the subject Of echoes Elisha Gray
| in the Chicago Times-HeraId writes:
If it were possible to know the relations
of all the rejecting surfaces of the storm
clouds to each other, the innunerable diff
ferences of distance and form, it would
still be impossible to analyze all the COM
| plicated motions and counter motions of
air waves that have been set up by a sim
gle lightning discharge. The sensation
| produced in the brain of the nearer is
| just complex as the mechanical condi-
! tons are in the outer world. The sensa-
ton, as whole, he calls rolling thunder
1t is simply the effect of the fist great
sound wave caused by the lightning dis
| charge echoing and re-echoing from
cloud to cloud till it has spent its force
! in the countless resistances which it
meets within its pathway.
When I was a child I grew up among
| the hills of southern Ohio. 1 well remem-
| Der going often to a certain spot among
| the hills to have a scrap with another
| naughty boy, who lived or seemed to
live, away up among the hills, long way
| off. In my childish imaginings I could see
hims hiding behind some crag or hillock
and only showing his head long enough
to throw back in perfect mimicry my own
words with the most unwearing prompt
ness. There were more than one of these
spirits; in fact a whole family Of them.
They seemed to be brothers, for they all
spoke with the same quality of voice.
Ea q one, however, had to be spoken to
from a different point of view. The only
| difference seemed to be that one of them
was very prompt and loud in his MINI
icry, almost catching the words out of my
mouth before they were spoken, while
| another was more deliberate and seemed
to take time to consider before sending
back his saucy message, and when 1t did
come it was not spoken in so loud a voice
as the first boy seemed to have.
When I grew older I learned something
of the laws of sound, and then 1 under
stood why I never could call my imagin
airy boys from their hiding place. 1 learn
ed that all this mimicry was simply re-
Election, or an echo, of my own voice, and
that the puick, loud voice came from the
Te1eCIlnp
that the one slower to respond and not so
loud was a reflection from hill greater
distance from me. I learned this lesson.
If you say nothing your words cannot
be thrown back to you Or, as the Arab
proverb has it: "Of thy unspoken word
thou art master; thy spoken words are
master of thee
I once stood in the base of the dome of
st. Paul's, London. 1 stood with my face
to the wall while a friend stood with his
back to me on the opposite side of the
dome, also facing the wall. In this posi-
ton we could converse with ease in
whisper. This was caused by series of
sound reflections that passed around each
inner half of the dome and met exactly
opposite to the point where the speaker
stood The sound was concentrated
where the listener stood somewhat in the
same manner as though spoken through
speaking tube. In one of the large
dome shaped rooms at the capitol at
Washington there are two points on the
floor where two persons may stand and
convrse with ease, in a very low voice,
though some distance apart. If one per-
son moves a few inches out of position
the conversation cannot be heard. The
ceiling in some way makes two focal
points the same as two parabolic mir
rors will for light or radiant heat as well
as for sound. In fact, the flight of sound
is governed by the same laws as thta of
light in almost, if not quite, all respects.
1t is reflected, refraCted and condensed
and dispersed, the same as light. Sound
may be distorted by this law of reflection
till there is no resemblance between the
original sound as it would seem to one
who was near by it's source, and as it
would seem to one who was off a consi-
derable distance, and so situated as to get
reflections Of the original from any points
differing not only in distance, but in the
character of the respective rejecting sur
faces. Almost everyone has seen himself
or herself in one of theses curious mir
rors so made as to produce distorted
image of whatever is reflected. By keep
ing this in mind you can get mental pic
ture of what takes place when sound is
distorted.
A minister once told me an amusing
story of how young man was called to
preach by one of these distorted sounds.
He did not feel quite sure Of his call, so
he submitted his case TO what he thought
would be crucial test. He lived in
country of high hills and sinuous valleys.
He betook himself to the fields, far away
from human habitation. and here he
PRAYED that if the Lord wanted him to
| preach He would give him an audible
sign of no uncertain sound. His prayer
was answered in the affirmative almost
as soon as uttered, in a most pronounced
and astounding way. There came TO his
| ears a most unearthly sound. unlike any
| thing that had ever come within hiseX-
perience. and he went home with & clear
cua conviction respecting his duty as
future minister of the gospel. Upon inyes-
tigation it was found that over in one OF
the valleys there was quietly grazing one
| Of those long cared, four footed animals
so noted for their wonderful vocti powers.
Just as the young man uttered his prayer
! the animal-whether in answer to the
| PRAYER or not, no one knows-spoke 70 the
| hills as only such animals can. The hills
played tenni~ with his voice. 1t bounded
| and rebounded from rock to crag and
| crag to peak and from a thousand other
rejecting surfaces until the voiee-not
/ lovely at its best-was twisted and distor-
| ted into a thousand hideous combna-
| tions Of all that was unlovely all that was
/ uncanny and all that was horrible. by the
! time it reached the ear of the young seek
! err of a sign.