Mr.
Thomas A. Edison recently came into this office, placed a little
machine on our desk, turned a crank, and the machine inquired as
to our health, asked how we liked the phonograph, informed us that
it was very well, and bid us a cordial good night. These remarks
were not only perfectly audible to ourselves, but to a dozen or
more persons gathered around, and they were produced by the aid
of no other mechanism than the simple little contrivance explained
and illustrated below.
The
principle on which the machine operates we recently explained quite
fully in announcing the discovery. There is, first, a mouth piece,
A, Fig. 1, across the inner orifice of which is a metal diaphragm,
and to the center of this diaphragm is attached a point, also of
metal. B is a brass cylinder supported on a shaft which is screw-threaded
and turns in a nut for a bearing, so that when the cylinder is caused
to revolve by the crank, C, it also has a horizontal travel in front
of the mouthpiece, A. It will be clear that the point on the metal
diaphragm must, therefore, describe a spiral trace over the surface
of the cylinder. On the latter is cut a spiral groove of like pitch
to that on the shaft, and around the cylinder is attached a strip
of tinfoil. When sounds are uttered in the mouthpiece, A, the diaphragm
is caused to vibrate and the point thereon is caused to make contacts
with the tinfoil at the portion where the latter crosses the spiral
groove. Hence, the foil, not being there backed by the solid metal
of the cylinder, becomes indented, and these indentations are necessarily
an exact record of the sounds which produced them.
It
might be said that at this point the machine has already become
a complete phonograph or sound writer, but it yet remains to translate
the remarks made. It should be remembered that the Marey and Rosapelly,
the Scott, or the Barlow apparatus, which we recently described,
proceed no further than this. Each has its own system of caligraphy
[sic], and after it has inscribed its peculiar sinuous lines it
is still necessary to decipher them. Perhaps the best device of
this kind ever contrived was the preparation of the human ear made
by Dr. Clarence J. Blake, of Boston, for Professor Bell, the inventor
of the telephone. This was simply the ear from an actual subject,
suitably mounted and having attached to its drum a straw, which
made traces on a blackened rotating cylinder. The difference in
the traces of the sounds uttered in the ear was very clearly shown.
Now there is no doubt that by practice, and the aid of a magnifier,
it would be possible to read phonetically Mr. Edison's record of
dots and dashes, but he saves us that trouble by literally making
it read itself. The distinction is the same as if, instead of perusing
a book ourselves, we drop it into a machine, set the latter in motion,
and behold! the voice of the author is heard repeating his own composition.
The
reading mechanism is nothing but another diaphragm held in the tube,
D, on the opposite side of the machine, and a point of metal which
is held against the tinfoil on the cylinder by a delicate spring.
It makes no difference as to the vibrations produced, whether a
nail moves over a file or a file moves over a nail, and in the present
instance it is the file or indented foil strip which moves, and
the metal point is caused to vibrate as it is affected by the passage
of the indentations. The vibrations, however, of this point must
be precisely the same as those of the other point which made the
indentations, and these vibrations, transmitted to a second membrane,
must cause the latter to vibrate similar to the first membrane,
and the result is a synthesis of the sounds which, in the beginning,
we saw, as it were, analyzed.
In
order to exhibit to the reader the writing of the machine which
is thus automatically read, we have had a cast of a portion of the
indented foil made, and from this the dots and lines in Fig. 2 are
printed in of course absolute facsimile, excepting that they are
level instead of being raised above or sunk below the surface. This
is a part of the sentences, "How do you do?" and "How do you like
the phonograph?" It is a little curious that the machine pronounces
its own name with especial clearness. The crank handle shown in
our perspective illustration of the device does not rightly belong
to it, and was attached by Mr. Edison in order to facilitate its
exhibition to us.
In
order that the machine may be able exactly to reproduce given sounds,
it is necessary, first, that these sounds should be analyzed into
vibrations, and these registered accurately in the manner described;
and second, that their reproduction should be accomplished in the
same period of time in which they were made, for evidently this
element of time is an important factor in the quality and nature
of the tones. A sound which is composed of a certain number of vibrations
per second is an octave above a sound which registers only half
that number of vibrations in the same period. Consequently if the
cylinder be rotated at a given speed while registering certain tones,
it is necessary that it should be turned at precisely that same
speed while reproducing them, else the tones will be expressed in
entirely different notes of the scale, higher or lower than the
normal note as the cylinder is turned faster or slower. To attain
this result there must be a way of driving the cylinder, while delivering
the sound or speaking, at exactly the same rate as it ran while
the sounds were being recorded, and this is perhaps best done by
well regulated clockwork. It should be understood that the machine
illustrated is but an experimental form, and combines in itself
two separate devices--the phonograph or recording apparatus, and
the receiving or talking contrivance which reads it. Thus in use
the first machine would produce a slip, and this would for example
be sent by mail elsewhere, together in all cases with information
of the velocity of rotation of the cylinder. The recipient would
then set the cylinder of his reading apparatus to rotate at precisely
the same speed, and in this way he would hear the tones as they
were uttered. Differences in velocity of rotation within moderate
limits would by no means render the machine's talking indistinguishable,
but it would have the curious effect of possibly converting the
high voice of a child into the deep bass of a man, or vice versa.
No
matter how familiar a person may be with modern machinery and its
wonderful performances, or how clear in his mind the principle underlying
this strange device may be, it is impossible to listen to the mechanical
speech without his experiencing the idea that his senses are deceiving
him. We have heard other talking machines. The Faber apparatus for
example is a large affair as big as a parlor organ. It has a key
board, rubber larynx and lips, and an immense amount of ingenious
mechanism which combines to produce something like articulation
in a single monotonous organ note. But here is a little affair of
a few pieces of metal, set up roughly on an iron stand about a foot
square, that talks in such a way, that, even if in its present imperfect
form many words are not clearly distinguishable, there can be no
doubt but that the inflections are those of nothing else than the
human voice.
We
have already pointed out the startling possibility of the voices
of the dead being reheard through this device, and there is no doubt
but that its capabilities are fully equal to other results just
as astonishing. When it becomes possible as it doubtless will, to
magnify the sound, the voices of such singers as Parepa and Titiens
will not die with them, but will remain as long as the metal in
which they may be embodied will last. The witness in court will
find his own testimony repeated by machine confronting him on cross-examination--the
testator will repeat his last will and testament into the machine
so that it will be reproduced in a way that will leave no question
as to his devising capacity or sanity. It is already possible by
ingenious optical contrivances to throw stereoscopic photographs
of people on screens in full view of an audience. Add the talking
phonograph to counterfeit their voices, and it would be difficult
to carry the illusion of real presence much further.
