Green-Mountain freeman. [volume] (Montpelier, Vt.) 1844-1884, 1882-05-10
Vibration.

WIZ dllUIi.
SOME CURIOUS FACTS ABOUT 1.-THE MAN
"FIDDLE DOWN. A BRIDGE
SINGING SANDS AND FLAMES,
Not long ago lady was singing in n
room where a chandelier with many glass
shades was hanging. The lady's voice
was loud and strong, and, as she continued
her song, her voice shattered one of the
glass shades to fragments.
Perhaps that sounds like a strange story
to you, my readers, but voices do and al
ways have done curious things. There
was once an innkeeper who added to his
earnings by letting his guests see him
break drinking cups with his voice. In
the Talmud, the Jews ancient book of
laws, there is something said about the
roparation that should be made when au
article is broken by the voice of any do
mcstic animal. We arc told that on the
wild mountain roads of Switzerland, the
muleteers tic up the bells of their mules,
lest the tinkling should start an avalanche.
A dog can play the pianofortc so far as to
make certain strings ybratc by his bark ;
and, after all, vibration of the strings is
what makes all the music of the piano
| forte.
Vibration is moving to and fro, as we
SEQ the pendulum of clock do. All things
have certain vibration, though it cannot
always be seen; some things have mum.
bcr of vibrations in their different parts.
And when tive things vibrate in time with
cash other, and are near each other,
though it is only air that connects thom,
the moving OF one is affected by that of the
other. The lady's voice broke tho shade
because they vibratcd in time with each
other, aud tho motion of the voice so in.
creased tho motion of the glass as to loosen
its particles and make it fall apart. When
two clocks, with pendulums that have the
same range Of vibration, are in the same
room, and the clock doors arc open, if the
pendulum oil one is set in motion, the
pendulum Of tho other will move, too.
This is tho principle: Every timo the
pendulum Of tho first clock vibrates, 1t
sends puff Of air in the direction of the
pendulum of tho second clock; and these
puffs, continued regularly, set the pendu-
lum of the second clock a-going When
two pianos arc in the same room, if the
strings of one are struck not only will
they vibrate, but also the corresponding
strings of the other piano, provided that
the forte pedal Of the second piano has
been depressed. And if you whistle a
note into piano or violin, the string of
the instrument in unison with that note
will audibly take it up.
In London boys carry milk about the
street in pals which hang from yoke on
their shoulders, and are held off from their
bodies by hoops Just below the waist. If
these boys kept up regular step, the vi
bration OF their bodies would increase the
vibration of the milk until that was spilled.
The little fellows may not quite understand
the philosophy Of the matter, but they
know they must change their step from
timo to tIme to keep their milk in the
pals.
A strong gust of wind will uproot a
majestic tree when it comes lust in time
with the trees own swing or vibration.
Some years ago there was considerable
annoyance in one of the mills in Lowell.
because the walls and floors of the build.
ing were shaken on certain days by the
machinery. At these times, pail of
water would almost be emptied of its con.
tents by the motion of the factory. 1t was
finally discovered that on the days of dis
turbance the machinery went at rate in
keeping with the vibration of tho building.
and the trouble was readily overcome BY
making the machinery work either faster
or slower than had been the custom.
The first iron bridge ever built was that
at Colebrook Dale, in England. While it
was building fiddler came along, and
exclaimed, 81 can fiddle that bridge
DOWN. The workmcn little alarmed,
bado him fiddle away to his hearts con.
tent. Whereupon, the musician tried one
tone after another upon his instrument,
until he hit upon one in tune with the
movement of the bridge, and then the
structure began to quiver so pcrccptibIy
that the laborerS begged him to cease and
let them alone.
1t is usual for 4 band Of soldiers when
they came TO a bridge to stop music and
walk over in broken file. Terrible calami-
ties have occurred in cases where this
precauton was not taken, rs at Anglers,
in France, where suspension bridge
broke in under n body of soldiers march
ing over in file, and two hundred and
eighty lives were lost. Robert Stephenson
said there was not so much danger when
a bridge was crowded with men or cattle,
or when cavalry were on it, as when sol,
dcrs passed over keeping step. Indeed,
if 1t were possible to make mouse walk
back and fourth continuously over a
bridge. keeping time with the vibration OF
the bridge, the mouse would eventually
destroy tho bridge.
When Calico discovered, that by blow
ing with his mouth upon pendulum each
time it moycd away from him, he could
greatly augment its velocity, he arrived at
the Important fact that slight impulse, if
regularly repeated, may become of great
consequence. On the same principle, a
heavy bell, that strong man can scarcely
move by one pull with all his might, can
be set i'll violent motion by mere boy, if
the lad gives regular pulls at the ropc,
because each pull slightly increases the
bells vibration. So, in swinging a child,
if push is given every time tho child
comes back, he will keep going higher and
higher until he finally goes over the tree ;
but break tho samencss Of the motion by
giving push before the swing has come
way back, and you will stop the swing.
Put tuning fork in connection with
another tuning fork of the same pitch,
and its strength is increased. The Same
effect is produced by holding a tuning
fork over the mouth OF bottle, if you ap.
ply one that vibrates in time with tho air
in the bottle. The sound called the song
of the sea, that is heard when she'll IS
held to the car, is the vibration of air in
tho shell. The music of the mighty organ
is caused by the vibration of air in the
pipes. Sound is tho sensation we expert
once from vibrations that reach tho car.
These vibrations are constantly passing
through tho air. but other matter may
convey them. Whom tree is folled, if a
person slightly scratches with a penknife
on ono end of the tree, another person
his car pressed at the other end-can dis
tinctly hear the sound, which in this in
stance is conveyed through the tree itself.
But what of the statement, that two
sounds can create silence?At first thought.
as some one has suggested, it seems as
absurd as to say that two loaves can make
| no bread. But when we reflect that sound