IMPROVEMENTS IN TEL GRUONIC TRANSMITTING APPARATIIS
Year: 1883

page_text: LETTERS PATENT to John Graham of N° 49 Belmont Street Haverstock Hill
in the County of Middlesex Electrician for an Invention of IMPROVEMENTS IN
TEL GRUONIC TRANSMITTING
APPARATIIS
PROVISIONAL SPECIFICATION left by the said John Graham at the Office
of the Commissioners of Patents on the 29th May 1883.
JOHN GRAHAM of N° 49 Belmont Street, Haverstock Hill in the County
of Middlesex, Electrician. IMPROVEMENTS IN TELEPHONIC TRANSMITTING
APPARATUS."
These improvements have for their object the production of a telephonic
transmitter which shall be suitable for employment under the varying conditions
of general use without such liability to derangement or necessity for delicacy of
adjustment or inanipulation requisite with those at present generally employed
whilst at the same time securing better results in speaking, simplicity of
construction and economy in manufacture-In carrying out my invention I provide
a flat or a concave plate (such plate having a flat rim around it covered with india
rubber or other suitable substance to serve as a cushion. This plate is retained in
position against the inside of the case and over a suitable hole or mouthpiece by
springs fixed to the case and pressing upon the said rim. Against this plate and
affixed thereto is a piece of carbon or other suitable material adapted to hold or
retain in position the end or ends of a carbon pencil or pencils or rods or pieces the
other end or ends thereof being supported by a metal or other suitable bracket
capable of being adjusted by screwing or otherwise relatively to the carbon or
other suitable piece. The pencil or pencils of carbon are retained in proper position
by passing into suitable recesses in the said metal bracket or piece of carbon
into projectious passing therefrom into suitable recesses in the end or ends of the
carbon pencil or pencils or other equivalent connection and the pencil or pencils or
rods of carbon are supported inclined to the plane of the mouth piece. And the

page_text: angle of inclination which I have at present found to give the best results is when
the carbon rods are inclined 5° to 20° to that plane
In operation the carbon plate is connected electrically with one pole of a battery
and the supporting plate of the pencil or pencils is connected in like manner to the
other pole of the battery through the primary wire of an induction coil or when
there is no induction coil employed the transmitter is joined up in direct circuit
with the line and battery in the usual manner
In place of the bracket supporting the carbon rods or pencils being adjusted to
those carbons such carbon pencil may be separately adjusted by separate screws as
they may be so adjusted or other order or adjusting means may be applied at
either or both ends of the carbon rods or pencils

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Graham in the Great Seal Patent Office on the 27th November
1883.
JOHN GRAHAM of N° 49. Belmont Street Haverstock Hill in the County
of Middlesex Electrician "IMPROVEMENTS IN TELEPHONIC TRANSMITTING
APPARATUS
37
These improvements have for their object the production of a telephonic
transmitter which shall be suitable for employment under the varying conditions
of general use without such liability to derangement or necessity for delicacy of
adjustment or manipulation requisite with those at present generally employed
whilst at the same time securing better results in speaking, simplicity of con-
struction, and economy in manufacture. In carrying out my invention I provide a
flat or a concave plate (such plate having a flat rim around it covered with india
rubber or other suitable substance to serve as a cushion. This plate is retained in
position against the inside of the case and over a suitable hole or mouthpiece by
springs fixed to the case and pressing upon the said rim. Against this plate and
affixed thereto is a piece of carbon or other suitable material adapted to hold or
retain in position the end or ends of a carbon pencil or pencils or rods or pieces
the other end or ends thereof being supported by a metal or other suitable bracket
capable of being adjusted by screwing or otherwise relatively to the carbon or
other suitable piece
The pencil or pencils of carbon are retained in proper position by passing into
suitable recesses in the said metal bracket or piece of carbon or onto projections
passing therefrom into suitable recesses in the end or ends of the carbon pencil or
pencils or other equivalent connection and the pencil or pencils or rods of carbon
are supported inclined to the plane of the mouth piece And the angle of inclination
which I have at present found to give the best results is when the carbon rods are
inclined 5° to 20° to that plane.
In operation the carbon plate is connected electrically with one pole of a battery
and the supporting plate of the pencil or pencils is connected in like manner to the
other pole of the battery through the primary wire of an induction coil or when
there is no induction coil employed the transmitter is joined up in direct circuit
with the line and battery in the usual manner.
In place of the bracket supporting the carbon rods or pencils being adjusted to
those carbons each carbon pencil may be separately adjusted by separate screws or
they may be so adjusted in other order or adjusting means may be applied at either
or both ends of the carbon rods or pencils.
Figures 1. and 2. shew by side and back view respectively, my improved carbon
transmitting instrument according to one arrangement o shews the receiving plate
having a cloth or other surrounding cushioning o'. 02 are springs which may be of
any convenient number to retain the plate o to the side of the case o³.-0* indicates
the position of the mouth piece. p is a piece of carbon connected to the plate o by
a screwed stem and nut o. This carbon p supports one end of another carbon
piece or a series of ends of carbon pieces the other end or ends thereof being
supported by a bracket q carrying adjusting screws q¹ one to each carbon piece r
employed. q are screws connecting this bracket q to the case,-p¹ indicates a wire
connecting the carbon piece p through the primary wire of an induction coil and q*
a wire connecting the bracket 9 in circuit the one with one pole and the other with
the other pole of a battery.
The carbon pieces r give the best results when supported suitably adjusted at an

page_text: angle of about 80° to 75° to the horizontal, or in other words when inclined at
from 5° to 20° to the plane of the mouth piece.
In place of the bracket supporting the carbon rods, or pencils, or other equivalent
pieces, being adjusted to those carbons, each carbon pencil may be separately
adjusted by separate screws, or they may be adjusted in other order, or adjusting
means may be applied at either, or both, ends of the carbon rods, or pencils.
Having thus described the nature of my invention and means adapted for
carrying the same into practical effect I would have it understood that I do not
confine myself to the precise details herein described and shewn But what I do
claim is the arrangement or construction of parts forming telephonic transmitting
apparatus substantially as and for the purpose herein described and shewn by the
drawings
In witness whereof I the said John Graham have hereunto set my hand and
seal this Twenty sixth day of November in the year of our Lord One thousand
eight hundred and eighty three:
Witness:
ALFRED GEORGE BROOKES.
59 Chancery Lane. London.
Patent Agent.
JOHN GRAHAM (L.S.)