Engineering,
THE TALKING PHONOGRAPH
We quote the following account of
Mr. Edison’s latest development of the telephone from the Scientific
American:
“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 above.
“The principle on which the machine operates we
explained quite fully in announcing the discovery. There is, first, a mouthpiece 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 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 calligraphy, 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
“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, analysed.
“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 of fig. 2 are printed in of course absolute fac-simile, excepting
that they are level instead of being raised above or sunk beneath the surface. This is 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
analysed 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, which produces the indented slip, 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 receiving 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 parlour organ. It has a keyboard, 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 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 a 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.”
Back to Mike
Penney’s "The
Sound of a Voice"