Year: 1886

page_text: I, EDWARD SAVAGE SPAULDING, a citizen of the United States of America,
residing at New York in the County and State of New York, gentleman, do
declare the nature of my invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:
My invention has relation to a method of reproducing articulate sounds, and the
novelty consists in the method of reproducing the human voice, through the
medium of crepitations or minute crackling sounds or detonations, and it parti-
cularly consists in causing the original disturbances in the transmitter to be
transmitted over the line, so as to affect the receiver and cause it to give forth a
series of crepitations or intermediate detonating sounds which will have the same
articulate value as the original sounds, whereby the human voice will be transmitted
electrically from one point to another without the use of magnets, diaphragms,
helices, secondary currents or induction coils, or any vibrating or sonorous material
whatever in the circuit, thus dispensing with the complicated parts, and the various
objections to which transmitters and receivers are liable and subject. And the
novelty consists in the method of transmitting and receiving articulate sounds
substantially as herein set forth.
In the accompanying drawing similar letters of reference indicate the same parts
of my invention.
Figure 1 is a plan of the apparatus employed to carry out my method of
transmitting sound.
Figure 2 is a similar view showing a modification of the form of a receiver, and
Figure 3 represents the circumferential connection of one of the carbon contact
points.
A, is an ordinary transmitter, B, the battery, C, the line and G, G, the grounds.
H illustrates the simplest form of my receiver or Krotophone in which D, D¹, are
the carbon points which form part of the circuit or line C, one of the points, D,
being rigidly secured in the receiver, H, and the other point, D¹, being secured
therein adjustably with reference to the other point by means of the screws F.
The receiver, H, containing the carbon pencil points, D, D', and adjusting screw F
constitute the complete receiver.

page_text: The transmitter, A, may be in one of the various forms of "Microphones" or in
fact any instrument may be used in which the sound or voice produces a series of
crepitations in the circuit which being transmitted over the line are reproduced in
their identical quality between the carbon points in the receiver, which repro-
duction will have the same relation to the original sound as the original sound or
voice had to the crepitations in the first instance.
In accordance with the spirit and letter of the Patent Laws, I will endeavor to
give as correct an explanation of the operation of my invention as I am able, based
upon the results of actual experiments and observations, without, however, in any
way asserting their infallibility, or wishing to provoke discussion as to the
correctness of the deductions.
For the sake of illustration we will assume that the circuit consists of a battery,
line and the receiver shown in Figure 1 be used as a transmitter and the same
instrument be used as a receiver proper. Assuming that the current passes through
the carbon pencils in parallel lines any disturbance of the point of contact of these
pencils in the transmitter, will produce a series of crepitations, which cause a series
of corresponding electrical impulses to be transmitted over the circuit; referring to
the receiver this circuit passing in parallel lines through the pencil D causes its
points of contact with the opposite pencil D¹ to vary by reason of the elongation
and contraction of said pencil D, due, for want of a better term, to the polarization
of the molecules or atoms of the pencil. Now assuming that through the pencil
the current passes in a series of many parallel lines, then the movement of the
atoms in each of these lines would be uniformly similar and in parallel lines and
thus, the disturbances created in the receiver correspond to the impulses affecting
it, which impulses in turn correspond with and depend on the primal disturbances
in the transmitter.
Now then it being shown that the polarization or disturbance of the atoms in
the pencil D in the receiver is produced I have noted that this result is accompanied
by a series of crepitations or crackling sounds which are clearly distinguishable
from even the faintest sounds, when produced by vibrations or other cause, and
from this distinction I infer that the said crepitations are strictly "neutral" and
so denominate them.
Therefore as such crepitations are individually neutral, when they are arranged
in constantly varying groups, corresponding exactly to the primal disturbances
which cause them, if articulate sounds be the primal cause of the disturbances in
the transmitter, articulate sounds will be the effect in the receiver.
I have found that when two pencils of carbon are used as a receiver, the sounds
will be audible and distinct, but faint, and to overcome this objection I have
replaced one of the pencils by a plate of carbon of such size and quality as to be
non-sonorous and non-vibratory, as shown in Figure 2. This plate I provide with
a circumferential ring, K, and said plate D¹ has a suitable elastic packing ring to
prevent fractures when rigidly secured in place in holder H. In this form of
receiver the current passing as before in parallel lines through the pencil D and
thence to the plate D' over the point of contact of the pencil, the current then
radially diverges in every direction towards the metallic ring and thence to the
ground as before; this construction gives an amplified sound and this result
I attribute to the radial or diverging paths the current takes. In the first form of
receiver described, the current passes in parallel lines and the movement of the
atoms on each of these lines is uniform and consequently the crepitations are faint,
but in the second. instance these several lines are not parallel but diverge and
hence an increased crepitating effect is produced.
I do not claim the transmitter, as my whole invention consists in the method of
reproducing the voice through the medium of the receiving device, and from this it
is clear that any form of carbon transmitter may be used in connection with my
receiver.
So far as I am aware of the efforts of prior inventors, they have employed some
means substantially different from mine; for example, the well known experiments

page_text: of Prof. Hughes, the microphone, requires a free pencil and the effect seems to
depend on the vibratory effort of the voice or other disturbing cause on the said
pencil causing it to move bodily and vary the amount of number of contact points,
while those of Bulmer show and claim a diaphragm, and Cook employs a vibrating
metallic diaphragm, all of which I distinctly disclaim.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
The method herein described of transmitting sounds electrically which consists
in conducting an electrical current to a given point and then dispersing said current
radially so as to produce and amplify the crepitations, substantially as herein
described.