Harper's Weekly 06/09/1888


THE PHONOGRAPH.

The speaking phonograph, which has recently
been improved, is now a practical machine for
recording dictation, and is unquestionably one of
the most astonishing and instructive instruments
ever produced. The accompanying illustrations
of the apparatus as perfected by Edison, its ori-
ginal inventor, and recently exhibited to the pub-
lic, show the method of dictating to and tran-
scribing from the phonograph, as well as the
instrument itself. About ten years ago Mr. Edi-
son
astonished the world by producing a ma-
chine which could record and reproduce sounds
of all kinds so perfectly that even articulate
speech, when recorded, could be preserved and
repeated at any time, not only intelligibly, but
with all the delicate expressions and inflections
of the voice of the speaker. This instrument,
like all early forms of inventions, had certain
drawbacks: it was clumsy, would only record
very loud sounds, and it required a skilled opera-
tor. Having freed himself from the cares inci-
dent to developing the electric light, Edison has
lately indulged his ambition of returning to his
favorite invention, which he alludes to as the
only one he ever made that is worth mentioning,
and after a comparatively brief effort gives us a
complete practical machine.


The improved phonograph consists of a small
brass cylinder mounted upon a spindle and ro-
tated at an absolutely steady speed by an electric
motor, with a very accurate governor concealed
in the bottom of the case. Upon this cylinder
is slipped a thin tube or hollow cylinder of wax
for receiving the record. A small sharp steel
cutter, attached to a web of silk which is stretched
across the end of the mouth-piece, or speaking
tube, is so placed and adjusted that its point cuts
a fine line in the wax as the cylinder revolves.
When sound waves strike this silk it yields to
their impulses, vibrating the cutter, and varying
the depth of the groove cut in the wax. To pre-
vent the tracing so formed from returning upon
itself after one revolution of the cylinder, the
entire mouth-piece carrying the cutter is caused
to move lengthwise along the cylinder, a hun-
dredth of an inch at each revolution, by a very
fine screw. In this way the line traced is made
a fine continuous spiral of great length, giving
room for a long message. The mouth-piece is so
arranged that it can be pushed aside to make
room for another mouth-piece carrying a blunt
point, which will lie in the groove so as to rise
and fall with every undulation in its depth, with-
out cutting the wax or altering the shape of the
tracing. This is called the reproducer. When
it is put in position, and the cylinder again ro-
tated under it after having received a record, its
pointer and sheet of silk are made to follow the
same motions or assume the same kind of vibra-
tions as those of the cutter in the recording
mouth-piece when that was vibrated by sounds or
talking as the cylinder was revolved in receiving
a record.


The new phonograph has a cutting tool which,
when required, trims off the surface of the wax
in advance of the recording needle, so as to re-
move the old record and prepare the surface for
the new one. The ordinary thin cylinders of
hardened wax, which have room for an eight-
minute conversation or letter, may be smoothed
off for a new record fifteen to twenty times. It
has been found, by actual test, that each record
will bear repetition aloud five hundred times.
Another feature of the improved instrument is a
lever, by pressing which in the same way that
one touches a piano key, the mouth-piece is raised,
and the phonograph instantly thrown out of ac-
tion, to allow a copyist to catch up, or to permit
an interruption, whether receiving or repeating,
without interfering with the uniform rotation of
the cylinder. By a little greater pressure on the
lever the mouth-piece is caused to move back so
as to repeat a portion of the inscription when
again lowered against the revolving cylinder, the
distance it moves back depending upon the length
of time the key is held down.


By this simple instrument for recording every
vibration of the air, and again imparting exactly
the same vibrations to the air, sounds of all kinds,
including all of the delicate secondary tones which
make up the character of any music, every inflec-
tion of the voice, and their peculiarities and char-
acteristics, are faithfully recorded and reproduced,
so that the voice may be even recognized, and it is
likely that by its sound an expert could identify
the make of a piano. The whole principle of the
phonograph, as well as of the telephone, is that
sounds or talking will set a plate into character-
istic vibration, and the sounds will be perfectly
reproduced by causing the plate to vibrate again
in the same way.


To explain clearly how it is possible for the
marvellous feats of the phonograph to be accom-
plished it is necessary to review one or two of the
principles of sound, and to explain the difference
between music and spoken words. Passing over
music and simple noises, and taking up the most
complex kind of sound, namely, articulate speech,
we enter upon a subject which was considered
spiritual rather than mechanical. The individu-
al peculiarities and delicate expressions of the
human voice have been looked upon as almost
belonging to the soul, and as therefore incapable
of reproduction. We recognize people by these
slight but sure differences in quality, and think
that “there is no mistaking that voice.” We
pay the same tribute to the individuality of each
kind of musical instrument, being able to dis-
tinguish one from another positively, by the quali-
ty of the sound only, after hearing precisely the
same musical note struck upon each. The first
question to be answered is, What is the differ-
ence in the sounds of different voices and of
different musical instruments by which we dis-
tinguish them, if it is difference neither in the
loudness nor in the pitch of the tone produced?
It is the simultaneous sounding of other notes
which accompany faintly the note played upon
the instrument, not loud enough to be heard, but
giving it richness and quality in precisely the
same way that a chord makes a richer sound than
a single note. These extra notes, sometimes call-
ed sympathetic vibrations, are too faint to be sep-
arately recognized, but they modify the original
note, giving it a richness, quality, or “timbre”
which differs for every instrument. The piano is
richer than the harp, because its strings are sur-
rounded by a case which imparts the vibrations
of each string to such of the other strings as are
in accord with it, thereby causing those nearest
in agreement to accompany every note struck.
The proportion of faint notes which accompany
the note played is different in different kinds of
musical instruments, being affected by the shape
of the case, the material, etc.; hence the differ-
ence in quality of sound.


In talking, the sounds of the voice are made
nearly all in one note, and articulation is simply
the effect of rapid and decided variations in the
quality or the timbre of the note, as if the instru-
ment which was sounding was rapidly changed
from an organ to a violin, a piano, etc., as the dif-
ferent syllables are pronounced. These changes
in the musical nature of the mouth are made by
using the tongue, palate, lips, and teeth to vary
its shape, and bring out the extra vibrations in
the various proportions of different musical in-
struments from moment to moment. In other
words, speech or articulation consists of one tone
produced by the voice or vocal chords, and then
modified by the various shapes which the mouth
can assume so as to possess at will the quality
giving properties of any instrument. This flexi-
bility of the voice is illustrated by the fact that
the voice can imitate almost any musical instru-
ment. Many people do not realize that a con-
versation is carried on in nearly a single tone,
with variations in its quality only. When we
vary the pitch of the notes produced by the voice,
as well as the quality, we are singing, and when
we vary the pitch without varying the quality,
that is, without pronouncing words, we are “hum-
ming” a tune, and it will be seen at once that in
doing this, as we are not required to change the
quality of the sounds, we may start the tune and
continue it in imitation of any musical instru-
ment, as a banjo or a trumpet.


All of these sounds and tones of every possi-
ble nature, simple and compound, are carried to
the ear by vibrations or waves of the air. A
simple note consists of a number of uniform
waves sent through the air, the number increas-
ing with the pitch of the note. The middle C of
the piano is the effect upon the ear of 256 waves
per second striking it. If two notes are struck at
once, the two sets of waves are blended, leaving
one set of waves a little larger, and containing all
the waves of both notes. In the same way, when
a rich sound is emitted or a word is pronounced,
the single set of irregular waves which are pro-
duced in the air contains the simple waves of the
key-note, with little waves added which represent
all the accompanying or sympathetic vibrations
that give the quality or character to the sound.
These minute waves unite with the larger ones,
but still retain their character and exert their
modifying influence in very much the same way
that ripples may appear upon the surface of
large waves of the ocean.


When these air waves strike any solid body
they set it into vibrations, exactly like those in
the air; and conversely, when a solid body can be
set into vibration, it imparts its motion to the air,
and produces the corresponding waves or sound.
This is the principle of both the phonograph and
the telephone. The latter, as its name implies,
reproduces sounds at a distant place by setting
the air there into vibrations like those that strike
the instrument at the receiving station. The
phonograph records the sounds received in such
a form that the record may be used at any time
to reproduce the sounds, the record being perfect
in every detail, so that the reproduced sounds
will be a perfect copy of the original in every re-
spect. In the phonograph the vibrations of any
sounds which reach it set in corresponding mo-
tion a cutting point, which is pressed against a
moving surface of wax so that every vibration
makes a corresponding undulation in the line cut
in the wax. To reproduce the vibrations, or
again create the sounds in the air, a dull point is
pressed against the wax, and when the undulating
line in the wax is moved under it, the point, in
following the undulations, is set into vibrations
which are an exact copy of those which made
the record in the wax. The small sheet of silk
to which the point is fixed imparts the sounds to
the air, and in this way we hear the original
sounds reproduced. The pronunciation of words
and the rendering of music by the phonograph are
perfect. The voice is distinct, and every word is
pronounced clearly, so that a copyist or composi-
tor may work directly from the dictation of the
instrument.


One of the essential features of the phono-
graph as well as the telephone is that there shall
be nothing used in the instrument which shall
have a characteristic sound of its own, like a
trumpet or a sounding-box. Any addition of
this kind tends to impart its own hollow sounds
to the tones of the instrument. It is for this
reason that all of the efforts during the last forty
years to make a talking machine have failed. It
is easily seen now that if for the purpose of pro-
ducing a sound like a trumpet we introduce a
trumpet as a part of our apparatus, the instru-
ment will fail when required to produce a sound
which is entirely free from any of the trumpet
peculiarities. For the same reason, the sounds
to be repeated by the phonograph would be more
distinct if not delivered to it through a speaking
tube, which muffles the sounds before they are
received, in consequence of which a muffled sound
is sometimes recorded. As in the telephone, the
progress in improving the clearness has been at
the expense of loudness. And to get perfect re-
sults it is necessary to make such a delicate rec-
ord that one has to apply tubes to the ears in
listening to the repetition.


The invention of the phonograph is a re-
markably impressive example of the possibility
of finally explaining and demonstrating any ap-
parently mysterious problem, and of utilizing the
knowledge gained. In thinking of its future it
is exceedingly interesting to imagine the results
which may be derived from studying its tracings.
It will furnish us the complete analysis of the
sounds of words, and it may give us curves which
can be copied in a larger size, like type, to be
used for stentorian talking machines.

Schuyler S. Wheeler.

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