Aberdeen herald. [volume] (Aberdeen, Chehalis County, W.T.) 1886-1917, 1906-11-08
VIBRATION.
Designs In Sand Formed by the Pro-
ductiOn Of Sounds.


duction CT Sounds.
Did you ever hear that you can make
drawings by sound. or, rather that the
sound vibrations will cause designs to
be made with the proper implements
at hand? Here is TIE way to do 1t:
At hardware store get piece Of
sheet brass oneeislNh Of an inch thick
and six inches square. The sheet
should be perfGctiy fiat, or If 1t Is not
it should be Nlmlnered so and the
edges rounded off, In the center OF the
sheet cut hole kree-siXteenths Of an
inch In diameter. If the sheet has
been hammered 1t must now be heated
In a redhot stove &nd cooled slowly.
Now cut six inch piece from a
broom handle and fix one end Of 1t
firmly In block Of wood. The other
end you must round of and screw the
plate Of brass an It.
If you draw violin bow over the
edge Of the brass plate tone will be
sounded. Practice this until the tone
Is quite clear and strong. Now sprin-
kle some sand on the plate, and the
grains will dance about while the note
is sounded, showing that the plate Is
In vibration.
Now put your finger on the edge Of
the plate in the middle Of one side. AT
the corner of the side at an angle of
forty-five degrees draw the bow, and
the sand will form in two lines Mt right
angles, starting from your finger. This
is because the plate now vibrates In
parts, one part moving up. while the
other moves down, and the lines be-
tween these Parts have no motion.
Therefore the sand settles In them.
BY drawing the bow ut regular dis
tunces from the finger or by touching
the plate in more than one place at a
time while SoIle one else draws the
bow variety Of sand figures will be
made.
If you will iaix Il little lycopodium
powder with t.. sand when the plate
vibrates it will :orm curious little
heaps and whr 20 is. which add to the
moving effect G. tie designs.
Instead of Il tra., plate you may use
one of glass six or eight inches square,
and its sharp "dg,s you may smooth
down with file noistened with tur-
pentine.
To prove to yourself that the plate Is
still or almost so ut the sand lines
make Il cardboard cone about ten inch-
es long, two and aalf inches in diam
eter at its larger end and small enough
<ho 9th al IN, int p,yh
tube, which should be about two feet
long. Let one person cause the plate
to vibrate, while another holds the
large end Of tie cone over the plate,
applying the rubber tube to the ear.
When the middle Of the cone Is exact
~ over sand line scarcely any tone ut
all will be heard, and the nearer the
cone Is to the sand line the weaker the
sound will be, while 1t will be clear
and strong at the farthest points from
the sand lines. proving that the sand
falls into lines, and as the parts Of the
plate move in opposite directions on
each side Of thu sand lines their effect
Is equalized or destroyed, causing no
sound in the CIR in the cone balance
when directly over those linas.-Cleve-
land Plain Dealer.
He Drew the Line.
Mr.. Cribbs-Mrs. Cribs, I have
borne with resignation - nay, even
notwithstanding chairs that wab-
bled, antique clocks that were always
thirteen hours behind time. antique
rugs that some prehistoric Turk wove,
antique china. antique bowls, pans and
kettles. All this have smiled at;
but when you give me antique eggs for
breakfast, I draw the line. madam-l
drow tho limo