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THE first patent that was ever granted on a
device for permanently recording the human voice
and other sounds, and for reproducing the same
audibly at any future time, was United States
Patent No. 200,251, issued to Thomas
A. Edison on February 19, 1878, the
application having been filed December 24,
1877. It is worthy of note that no
references whatever were cited against the
application while under examination in the
Patent Office. This invention therefore,
marked the very beginning of an entirely new
art, which, with the new industries attendant
upon its development, has since grown to occupy
a position of worldwide reputation.
That the invention was of a truly fundamental
character is also evident from the fact that
although all "talking- machines" of to-day
differ very widely in refinement from the first
crude but successful phonograph of Edison,
their performance is absolutely dependent upon
the employment of the principles stated by him in
his Patent No. 200,251. Quoting from
the specification attached to this patent, we
find that Edison said:
"The invention consists in arranging a plate,
diaphragm or other flexible body capable of being
vibrated by the human voice or other sounds, in
conjunction with a material capable of
registering the movements of such vibrating body
by embossing or indenting or altering such
material, in such a manner that such register
marks will be sufficient to cause a second
vibrating plate or body to be set in motion by
them, and thus reproduce the motions of the
first vibrating body."
It will be at once obvious that these words
describe perfectly the basic principle of every
modern phonograph or other talking-machine,
irrespective of its manufacture or trade name.
Edison's first model of the phonograph is shown
in the following illustration.
It consisted of a metallic cylinder having a
helical indenting groove cut upon it from end to
end. This cylinder was mounted on a shaft
supported on two standards. This shaft at one
end was fitted with a handle, by means of which
the cylinder was rotated. There were two
diaphragms, one on each side of the cylinder,
one being for recording and the other for
reproducing speech or other sounds. Each
diaphragm had attached to it a needle. By means
of the needle attached to the recording
diaphragm, indentations were made in a sheet of
tin-foil stretched over the peripheral sur-
face of the cylinder when the diaphragm was
vibrated by reason of speech or other sounds.
The needle on the other diaphragm subsequently
followed these indentations, thus reproducing
the original sounds.
Crude as this first model appears in comparison
with machines of later development and
refinement, it embodied their fundamental
essentials, and was in fact a complete,
practical phonograph from the first moment of its
operation.
The next step toward the evolution of the
improved phono- graph of to-day was another
form of tin-foil machine, as seen in the
illustration.
It will be noted that this was merely an
elaborated form of the first model, and embodied
several mechanical modifications, among which
was the employment of only one diaphragm for
recording and reproducing. Such was the general
type of phonograph used for exhibition purposes
in America and other countries in the three or
four years immediately succeeding the date of
this invention.
In operating the machine the recording diaphragm
was advanced nearly to the cylinder, so that as
the diaphragm was vibrated by the voice the
needle would prick or indent a wave-like record
in the tin-foil that was on the cylinder. The
cylinder was constantly turned during the
recording, and in turning, was simultaneously
moved forward. Thus the record would be formed
on the tin-foil in a continuous spiral line.
To reproduce this record it was only necessary
to again start at the beginning and cause the
needle to retrace its path in the spiral line.
The needle, in passing rapidly in contact with
the recorded waves, was vibrated up and down,
causing corresponding vibrations of the
diaphragm. In this way sound-waves similar to
those caused by the original sounds would be set
up in the air, thus reproducing the original
speech.
The modern phonograph operates in a precisely
similar way, the only difference being in
details of refinement. In- stead of
tin-foil, a wax cylinder is employed, the
record being cut thereon by a cutting-tool
attached to a diaphragm, while the reproduction
is effected by means of a blunt stylus similarly
attached.
The cutting-tool and stylus are devices made of
sapphire, a gem next in hardness to a diamond,
and they have to be cut and formed to an exact
nicety by means of diamond dust, most of the
work being performed under high-powered
microscopes. The minute proportions of these
devices will be apparent by a glance at the
accompanying illustrations, in which the object
on the left represents a common pin, and the
objects on the right the cutting-tool and
reproducing stylus, all actual sizes.
In the next illustration (Fig. 4) there is
shown in the upper sketch, greatly magnified,
the cutting or recording tool in the act of
forming the record, being vibrated rapidly by
the diaphragm; and in the lower sketch,
similarly enlarged, a representation of the
stylus travelling over the record thus made, in
the act of effecting a reproduction.
From the late summer of 1878 and to the fall
of 1887 Edison was intensely busy on the
electric light, electric railway, and other
problems, and virtually gave no attention to the
phonograph. Hence, just prior to the
latter-named period the instrument was still in
its tin-foil age; but he then began to devote
serious attention to the development of an
improved type that should be of greater
commercial importance. The practical results
are too well known to call for further comment.
That his efforts were not limited in extent may
be inferred from the fact that since the fall of
1887 to the present writing he has been
granted in the United States one hun- dred and
four patents relating to the phonograph and its
accessories.
Interesting as the numerous inventions are, it
would be a work of supererogation to digest all
these patents in the present pages, as they
represent not only the inception but also the
gradual development and growth of the wax-record
type of phonograph from its infancy to the
present perfected machine and records now so
widely known all over the world. From among
these many inventions, however, we will select
two or three as examples of ingenuity and
importance in their bearing upon present
perfection of results
One of the difficulties of reproduction for many
years was the trouble experienced in keeping the
stylus in perfect en- gagement with the
wave-like record, so that every minute
vibration would be reproduced. It should be
remembered that the deepest cut of the recording
tool is only about one- third the thickness of
tissue-paper. Hence, it will be quite
apparent that the slightest inequality in the
surface of the wax would be sufficient to cause
false vibration, and thus give rise to distorted
effects in such music or other sounds as were
being reproduced. To remedy this, Edison
added an attachment which is called a "floating
weight," and is shown at A in the illustration
above.
The function of the floating weight is to
automatically keep the stylus in close engagement
with the record, thus insuring accuracy of
reproduction. The weight presses the stylus to
its work, but because of its mass it cannot
respond to the extremely rapid vibrations of the
stylus. They are therefore communicated to the
diaphragm.
Some of Edison's most remarkable inventions
are revealed in a number of interesting patents
relating to the duplication of phonograph
records. It would be obviously impossible,
from a commercial standpoint, to obtain a
musical record from a high-class artist and sell
such an original to the public, as its cost
might be from one hundred to several thousand
dollars. Consequently, it is necessary to
provide some way by which duplicates may be made
cheaply enough to permit their purchase by the
public at a reasonable price.
The making of a perfect original musical or
other record is a matter of no small difficulty,
as it requires special technical knowledge and
skill gathered from many years of actual
experience; but in the exact copying, or
duplication, of such a record, with its many
millions of microscopic waves and sub-waves,
the difficulties are enormously increased. The
duplicates must be microscopically identical with
the original, they must be free from false
vibrations or other defects, although both
original and duplicates are of such easily
defacable material as wax; and the process must
be cheap and commercial not a scientific
laboratory possibility.
For making duplicates it was obviously necessary
to first secure a mold carrying the record in
negative or reversed form. From this could be
molded, or cast, positive copies which would be
identical with the original. While the art of
electroplating would naturally suggest itself as
the means of making such a mold, an apparently
insurmountable obstacle appeared on the very
threshold. Wax, being a non- conductor,
cannot be electroplated unless a conducting
surface be first applied. The coatings
ordinarily used in electro- deposition were
entirely out of the question on account of
coarseness, the deepest waves of the record
being less than one-thousandth of an inch in
depth, and many of them probably ten to one
hundred times as shallow. Edison finally
decided to apply a preliminary metallic coating
of infinitesimal thinness, and accomplished this
object by a remarkable process known as the
vacuous deposit. With this he ap- plied to the
original record a film of gold probably no
thicker than one three-hundred-thousandth of an
inch, or several hundred times less than the
depth of an average wave. Three hundred such
layers placed one on top of the other would make
a sheet no thicker than tissue-paper.
The process consists in placing in a vacuum two
leaves, or electrodes, of gold, and between
them the original record. A constant discharge
of electricity of high tension between the
electrodes is effected by means of an
induction-coil. The metal is vaporized by this
discharge, and is carried by it directly toward
and deposited upon the original record, thus
forming the minute film of gold above mentioned.
The record is constantly rotated until its
entire surface is coated. A sectional diagram
of the apparatus (Fig. 6.) will aid to a
clearer understanding of this ingenious process.
After the gold film is formed in the manner
described above, a heavy backing of baser metal
is electroplated upon it, thus forming a
substantial mold, from which the original record
is extracted by breakage or shrinkage.
Duplicate records in any quantity may now be
made from this mold by surrounding it with a
cold-water jacket and dipping it in a molten
wax-like material. This congeals on the record
surface just as melted butter would collect on a
cold knife, and when the mold is removed the
surplus wax falls out, leaving a heavy deposit
of the material which forms the duplicate
record. Numerous ingenious inventions have been
made by Edison providing for a variety of rapid
and economical methods of duplication, including
methods of shrinking a newly made copy to
facilitate its quick removal from the mold;
methods of reaming, of forming ribs on the
interior, and for many other important and
essential details, which limits of space will
not permit of elaboration. Those mentioned
above are but fair examples of the persistent and
effective work he has done to bring the
phonograph to its present state of perfection.
In perusing Chapter X of the foregoing
narrative, the reader undoubtedly noted
Edison's clear apprehension of the practical
uses of the phonograph, as evidenced by his
prophetic utterances in the article written by
him for the North American Review in June,
1878. In view of the crudity of the
instrument at that time, it must be acknowl-
edged that Edison's foresight, as vindicated
by later events was most remarkable. No less
remarkable was his intensely practical grasp of
mechanical possibilities of future types of the
machine, for we find in one of his early
English patents (No. 1644 of 1878)
the disk form of phonograph which, some ten to
fifteen years later, was supposed to be a new
development in the art. This disk form was also
covered by Edison's application for a United
States patent, filed in 1879. This
application met with some merely minor technical
objections in the Patent Office, and seems to
have passed into the "abandoned" class for want
of prosecution, probably because of being
overlooked in the tremendous pressure arising
from his development of his electric-lighting
system.
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