IMPROVEMENTS IN TELEPHONES
Year: 1880

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields, in the
County of Middlesex, Gentleman, for an Invention of "IMPROVEMENTS IN
TELEPHONES." A communication from abroad by Ernest Marx, Frank
Aklemm, and Julius Kayser, all of New York, United States of America,
and Louis Davis, of Montreal, Canada.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at the
Office of the Commissioners of Patents on the 27th March 1880.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN TELEPHONES." A communication from abroad by
Ernest Marx, Frank Aklemin, and Julius Kayser, all of New York, United States
of America, and Louis Davis, of Montreal, Canada.
This Invention relates to certain novel features of construction in the transmitters
of telephones, and is an improvemont upon the construction described in a
Provisional Specification filed by Louis Davis with his application for Letters
Patent, dated the 27th January 1880, No. 351.
According to the said former Invention the carbon point is secured to a holder
attached to the end of a spring arm which forms one electrode, and which is
adjustable by means of a screw to regulate the mechanical contact of the carbon
point with the platinum point in the centre of the diaphragm.
The present Invention has for its object to dispense in a measure with the spring
properties of the arm to which the carbon holder is attached and to avoid the
frequent adjustments rendered necessary by inherent properties of a spring, and
with these ends in view the Invention consists broadly in securing the carbon point
and holder to the end of a practically rigid arm in such a manner that mechanical
contact between the carbon point and electrode or platinum point on the diaphragm
is maintained by the gravity of the holder so that variations of temperatures
and conditions will not affect the same, as will be hereinafter and in detail
explained.
In carrying out this Invention an ordinary transmitter box is provided having a
bevelled opening or mouth piece leading to the diaphragm, the latter being held in
contact with a felt or other suitable damping ring or shoulder by means of a metallic
spring arm, which is secured at one end by screws to the front piece of the box, and

page_text: "
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by screws at the other end to the diaphragm, so that the arm is practically a spring
hinge. On the opposite side to this spring hinge is secured to the front pieco a
practically rigid metallic arm which is fastened in place by screws. The free end
of this arm is bifurcated or mortised, and pivoted therein by adjustable screw pivots
is a knee or metal angle piece, to the lower extremity of the vertical leg of which is
secured in any suitable manner a carbon button which is kept in contact with the
platinum point in the centre of the diaphragm by the gravity of the horizontal leg
of the knee.
A metal bridge is secured to the front piece at right angles, preferably to the
rigid arm, and this bridge and the knee are electrically connected by a conducting
wire, the other necessary connections being made by wires from the one end of the
bridge and the end of the spring hinge. The rigid arm is secured to the front
piece by a post or block and screw, and with its lower end inclined towards the
diaphragm, a screw being provided which has a thread bearing in the arm and its
end in contact with the front piece, or a bearing block secured thereto, so that the
inclination of the said arm may be slightly adjusted or varied by the act of turning
the screw.
The necessary connections with the induction coil, telephone posts, and main line
are made in the usual manner well know to those skilled.
From the foregoing description it will be readily understood that the carbon point
is kept in mechanical contact with the platinum point in the diaphragm entirely by
the gravity of the knee (which may be adjusted by the screw), and that there is no
possibility of the parts getting out of adjustment. I do not wish to confine myself
to the exact angular form of the knee as it is apparent that any other form which
vill locate a weight beyond the pivot to form a leverage will accomplish the same
result.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Henry Johnson in the Great Soal Patent Office on the 21st
September 1880.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "LMPROVEMENTS IN TELEPHONES." A communication from abroad by
Ernest Marx, Frank Aklemm, and Julius Kayser, all of New York, United States
America, and Louis Davis, of Montreal, Canada.
The said Invention relates to certain novel features of construction in the
transmitters of telephones, and is an improvement upon the construction described
in the Specification to Letters Patent granted to Louis Davis, dated the Twenty
seventh January, One thousand eight hundred and eighty, No. 351.
According to the said former Invention the carbon point is secured to a holder
attached to the end of a spring arm which forms one electrode, and which is
adjustable by means of a screw to regulate the mechanical contact of the carbon
point with the platinum point in the centre of the diaphragm.
The present invention has for its object dispensing in a measuro with the spring
properties of the arm to which the carbon holder is attached, and avoiding the
frequent adjustments rendored necessary by inherent properties of a spring, and
with these ends in view the Invention consists broadly in securing the carbon
point and holder to the end of a practically rigid arm in such a manner that
mechanical contact between the carbon point and electrode or platinuin point on
the diaphragm is maintained by the gravity of the holder, so that variations
of temperatures and conditions will not affect the same, as hereinafter fully
explained.
And in order that the said Invention may be fully understood, I shall now
proceed more particularly to describe the same, and for that purpose shall refer
to the several Figures on the annexed Sheet of Drawings, the same letters of
reference indicating corresponding parts in both the Figures.
Figure 1 of the accompanying Drawings represents a longitudinal section of a
portion of a transmitter box with tho said Invention applied thereto, and Figure 2
is an elevation of the same viewed from the inside.
A is the front of an ordinary transmitter box, and B the bevelled opening or
mouthpiece leading to the diaphragm C; the latter is held in contact with a felt or
other suitable damping ring or shoulder D by means of a metallic spring arın E
which is secured at one end by screws a, a, to the front piece A and by screws b, b,
at the other end to the diaphragm so that the arm E is practically a spring hinge.
On the opposite side to this spring hinge is secured to the piece A a practically
rigid metallic arm F which is fastened in place by screws c, c. The free end of
this arm is bifurcated or morticed, and in the mortised portion is pivotted by
adjustable screw pivots d, d, a knee or metal angle piece G, to the lower extremity
of the vertical leg of which is secured in any suitable manner a carbon button H,
which is kept in contact with the platinum point e in the centre of the diaphragm
by the gravity of the horizontal leg of the knee.
I is a metal bridge secured to the picce A at right angles preferably to the
arm F, and this bridge and the knee G are electrically connected by a conducting
wire f, the other necessary connections being made by wires K, L, from the one end
of the bridge I and the end of the spring hinge E respectively. The ann F is secured
to the piece A by a post or block M and screws c, c, and with its lower end inclined
towards the diaphragm; O is a screw which has a thread bearing in the arm F', and
its end in contact with the piece A or a bearing block secured thereto, so that the
inclination of the said arm may be slightly adjusted or varied by the act of turning
the said screw,

page_text: The necessary connections with the induction coil, telephone posts, and main line
are made in the usual manner well known to those conversant with telephones.
From the foregoing description it will be readily understood that the carbon point
is kept in mechanical contact with the platinum point in the diaphragm entirely by
the gravity of the knee G (which may be adjusted by the screw O) and that there
is no possibility of the parts getting out of adjustment.
Having now described and particularly ascertained the nature of the said
Invention, and the manner in which the same is or may be used or carried into
effect, 1 would observe in conclusion that I do not confine myself to the exact
angular formn of the knee G as it is apparent that any other form which will locate
a weight beyond the pivot to form a leverage will accomplish the same result, but
what I consider to be novel and original, and therefore claim as the Invention
secured to mo by the hereinbefore in part recited Letters Patent is,―
First. The carbon holder G pivoted to the end of an arın F, substantially as and
for the purpose herein before described.
Second. In combination with the vibrating carbon holder G and arm F, the
bridge I, and connecting wire f, substantially as and for the purpose hereinbefore
described.
Third. The arm F inclined towards the diaphragm and provided with an adjusted
screw O, substantially as and for the purpose hereinbefore described.
Fourth. The combination with the mouth piece of a telephone transmitter of the
diaphragm C secured by a spring hinge E, the arm F, knee G, and carbon button H,
substantially as and for the purpose herein before described.
In witness whereof, I, the said John Henry Johnson, have to this my
Specification set my hand and seal, this Twentieth day of September,
One thousand eight hundred and eighty.
HAHVAA