The Hartford republican. (Hartford, Ky.) 18??-1926, 1915-12-31
MAKING A RECORD
Methods by Which a Photograph
Disk Is Produced.
CATCHING THE SOUND WAVES.
They Arc First Imprisoned In Wax and
Then Transferred to a Negative In
Copper, and From This Master Mold
the Records Are Obtained.

men transferred to a Negative In
Copper, and From This Master Mold
the Records Are Obtained.
The Edison phonograph, the graphic.
phone type perfected by Bell and Tain
ter and the gr0mophone type by Bcr-
liner are all based on substantially the
same principle. Sound waves set up in
the air by any sound are allowed TO
strike delicately held Diaphragm.
which vibrates under the impact OF the
sound waves. The vibrations are made
to leave n record on u suitable me.
dunn, and this sound record Is used to
perform the Inverse operation when It
Is required TO reproduce recorded
sounds-that Is. the record IL made to
vibrate sensitive diaphragm and set
up In the air particular waves, which
convey to the ear the impression Of
sound
The differences I'm the systems are I'm
the way In which the vibrations are re.
corded. The disk record which mnde
the machine popular, was first manu-
factured In the United States I'm 1897
improvements Ia the machine and In
the needles followed
!. To make n gramOphone record per.
son sings before the mouth of a horn,
the object of which Is 10 concentrate
the energy Of the sound waves upon
the recording diaphragm. At the mar.
row end OF the horn are the recording
sound box and the machine with its
attendant expert. There Is screen
between singer and operator to guard
the secrets of the sound box On the
farther side of the screen Is u hori.
zontal table carrying wax tablet.
rotated beneath the recording sound
box Mt uniform speed. usually about
seventy-six revolutions per minute. As
the table rotatcs IL travels laterally at
uniform speed. and the wax tablet
Is thus caused 10 travel slowly under
the stationary recording box. The
sapphire cutting point Is lowered so
as to enter the wax three and one-half
to four one-thousandths Of an inch. and
as the machine runs Il cuts fine spiral
groove. running from the edge TO the
center. The construction Of the sound
box Is secret. us Is the composition Of
the wax tablet
The next step I'm the process is the
tive In copper. The wax Is busted with
graphite and worked into the grooves
with badger brush u make II cleo
tro-conductive: then II Is lowered into
an electrolytic bath of copper salt solu-
ton. The wax is kept in continuous
motion IN the bath until the copper
shell Is ninetenths of n millimeter In
thickness.
This negative Is n master, and from
this few commercial samples can be
pressed 10 test the quality of the rec
ord. The manufacturers. however.
wish to make thousands Of copies
without hurting their master: there
fore they make duplicates Of their
master by taking impressions In wax
composition. from which working mat
rices are made. Then copper shells
are obtained from these In the same
way. The copper shell is then backed
by brass plate one-half inch I'm thick
nCss ny SoiutiihE pitssuCs
Then the matrix Is nickel plated on
the recorded side In order to wear bet
ter and after polishing is ready for
the pressing machine. The commercial
record is pressed into some substancel
hard ut normal temperature and plasticI
under heat and very hard and smooth.
Various compounds are employed byI
different makers, but shellac is the!
principal Ingredient Shellac, wood
charcoal, heavy spar and earthly color
ing matter In certain proportions arel
used.
This compound after careful mixins)
is rolled into thin sheets and divided
into sections. one for each record. TheI
section Is then pressed by hydraullc|
press. The matriy Is heated and placed
face up In a mold. the label Is placed
face down on the matrix. and on this isl
placed I'm a warm. plastic state enough
material for one record. Both halves|
of the press are furnished with coolingI
plates, through which streams Of water|
can be passed. and the surfaces are|
cooled quickly. The record Is then re-
moved, the edges trimmed with emery
wheels, and It is then ready for SALE
New York Times