Year: 1898

page_text: Date of Application, 27th Dec., 1898
Complete Specification Left, 19th Sept., 1899-Accepted, 2nd Dec., 1899
A communication from abroad by ALLEN THOMAS NYE, of No. 36, West 120th
Street, New York, in the United States of America.
I, PHILIP MIDDLETON JUSTICE, of 55 and 56, Chancery Lane, in the County of
Middlesex, Fellow of the Chartered Institute of Patent Agents, do hereby
declare the nature of this invention to be as follows:-
This invention relates to those instruments through which sound waves are
caused to act upon the electrical current passing over the conductors of a telephone
system, such instruments being commonly known as transmitters In such
instruments, as 18 well understood, granular carbon 18 commonly interposed
between the two electrodes, the one of which is carried by the vibrating diaphragm
while the other is supported by the frame or case of the transmitter Commonly
the receptacle which contains the granular carbon is carried by the frame or
shell of the transmitter and the plate which forms the other electrode (the base
of the cup forming one of the electrodes) 18 secured to the diaphragm With this
arrangement the granular carbon between the electrodes gradually becomes
packed so hard as to lose its desirable qualities and interfere with the distinct
transmission of speech Various ways of preventing this packing of the granular
carbon or rather of loosening it up after it has become packed have been resorted
to, as by striking the transmitter sharply or by rotating the transmitter upon its
axis at intervals. It has been discovered that by securing the cup or receptacle
to the diaphragm, so that the former shall partake of the vibrations of the latter,
the granular carbon will be kept in a state of constant agitation while the
instrument is in use and the packing of such granular carbon will be prevented
entirely. It is proposed therefore to secure the cup or receptacle as thus described
and to support the other electrode or plate upon the frame or shell of the
transmitter.
Dated this 27th day of December 1898.
A communication from abroad by ALLEN THOMAS NYF, of 36, West 120th
Street, New York, in the United States of America
I, PHILIP MIDDLETON JUSTICE, of 55 and 56, Chancery Lane, in the County of
Middlesex, Fellow of the Chartered Institute of Patent Agents, do hereby

page_text: declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:
1
It is well known that the granular carbon which is cominonly employed between
the electrodes of a telephone transmitter has a tendency to become packed in use
so hard as to lose its desirable qualities whereby the distinct transmission of
speech is interfered with In the present improved transmitter the granular
carbon 16 subjected to the action of the vibrations of the transmitter diaphragm,
so that the cai bon as a body shall partake of such vibration, whereby it will be
kept in such a state of constant agitation while the instrument is in use that
the objectionable packing will be prevented, especially when the carbon 18
thoroughly loosened up from time to time. The means whereby these results
are accomplished will be fully described hereinafter with reference to the
accompanying drawing, in which,—
Figure 1 is a longitudinal central section of a transmitter which embodies the
present improvement,
Figure 2 is a section on an irregular plane indicated at the line 2–2 of
Figure 1; and
Figure 3 is an end view of the carbon retaining cup
The casing A, the diaphragm B, the cap or holder C by which the diaphragm
18 supported, and the mouth piece D may be of any usual or suitable form and
allangement A budge piece E 18 secured to the cap or holder C and serves
to support one of the electrodes which is represented at Fas having a screw
threaded shank f which engages the bridge piece, a binding screw 1 serving
to hold the electiode firmly in adjusted position The other electrode 18 secured
as usual to the diaphragm B, being repiesented at F¹.
The granular carbon, indicated at G, 18 interposed between the two electrodes
and is subject to the action of the electrode F which is mounted upon the
diapliagm An enclosing cup or receptacle to retain the granular carbon 18
commonly secured to the fixed electrode F, the result of this usual arrangement
being that the carbon becomes packed in the continued use of the instrument. 'In
accordance with this invention the cup or receptacle, represented at G¹ is secured
with the electiode F to the diaphragm B, so that the caibon, as a body, partakes
of the vibrations of the diaphragm while the instrument is in use, and the packing
of the carbon is thereby prevented, and the cup is 80 formed as to make it possible
to loosen up the carbon thoroughly from time to time. For convenience the
cup oi receptacle G₁ may be slipped loosely upon the shank of the electrode F¹
and be securely held in position by a thin nut f³, but rotatable on said shank.
The usual insulation is provided within the cup as at 9, an insulating washer gl
being mounted loosely on the shank of the fixed electrode l' to close the open end
of the cup or receptacle and thereby retain the granulated carbon within said cup or
receptacle The cavity of the cup, as clearly shown in Figure 3, is eccentric and
the cup is normally placed with the greatest eccentricity of the cavity down.
Whenever the transmission of speech is such as to indicate that, the carbon 18
becoming packed somewhat, the cap C is removed with its attached parts and the
cup is rotated by the fingers. As the carbon naturally gathers in the part of
greatest eccentricity the rotation of the cup not only overturns the mass of
carbon but grinds it against the electrodes, thus loosening up the mass and
separating the granules thoroughly.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, as communicated
to me by my foreign correspondent, I declare that what I claim 18:-
1 A telephone transmitter having a fixed electrode, a movable electrode secured
to the diaphragm, and a rotatable cup or receptacle to retain granulated carbon
between the electrodes secured with the movable electrode to the diaphragm, and

page_text: having an eccentric cavity for the granulated carbon whereby the granulated carbon
as a body is made to partake of the vibrations of the diaphragm and 18 prevented
from being packed, and can be thoroughly loosened up from time to time by
rotating the cup, substantially as shown and described
2. In a telephone transmitter, the combination with a cap or holder, & dia-
phragm carried by said cap or holder and a bridge piece secured to said cap or
holder, of an electrode mounted adjustably in said bridge piece, an electrode
mounted on the diaphragm, and a rotatable cup or receptacle secured with the
last named electrode to the diaphragm to retain granulated carbon between the
electrodes and having an eccentric cavity for the granulated carbon, whereby
the granulated carbon as a body is made to partake of the vibrations of the
diaphragm and prevented from becoming packed and can be thoroughly loosened
up from time to time by rotating the cup, substantially as shown and described.
Dated the 19th day of September 1899
PHILIP M. JUSTICE