IMPROVEMENTS IN TELEPHONIC
Year: 1883

page_text: LETTERS PATENT to Edgar George, Francis Agnew Pocock, John Saunders
Muir, and John Saunders Muir, Junior all of St Stephens Chambers in
the city of London for an Invention of IMPROVEMENTS IN TELEPHONIC
COMPLETE SPECIFICATION filed by the said Edgar George, Francis Agnew
Pocock, John Saunders Muir and John Saunders Muir, Junior, at the Office
of the Commissioners of Patents on the 7th September 1883.
EDGAR GEORGE, FRANCIS AGNEW POCOCK, JOHN SAUNDERS MUIR and JOHN
SAUNDERS MUIR, Junior all of St. Stephens Chambers in the city of London
IMPROVEMENTS IN TELEPHONIC APPARATUS
Our invention relates to instruments for the transmission by electricity of
articulate and other sounds and has for its object the attainment of the utmost
simplicity combined with efficiency in such instruments.
To carry out these objects we use or employ in the transmitter any semiconductor
of electricity such for instance as coke or carbon in combination with platinum or
carbon and the microphone therewith formed is attached to wires which are
incapable of inductive action and are stretched tightly across a frame and the said
microphone is located centrally in the said frame opposite the inner opening of a
suitable mouthpiece so that the sound waves shall impinge directly thereon and
set up vibrations in accordance with their varying tone or pitch whereby a
variation is caused in the resistance in accordance with these vibrations. This
result is by our method obtained by molecular disturbance and not by the aid of a
tension regulator or by the intervention of a diaphragm and it is therefore certain
and effective in its operation while the instrument is simplified in its construction.
In the magneto electric receiver we use according to one form as hereinafter
described a fixed solenoid and suspend within its hollow centre a core which is.
attached by a light rod of brass wood vulcanite or other non-magnetic substance
to a disc or plate of cork wood vulcanite or other suitable material which disc or
plate is attached to wires of a non-magnetic substance such for instance as German:
silver or brass stretched tightly across a frame. This said core may be made of
LDS31

page_text: soft iron or highly magnetized steel or may be a soft iron bobbin upon which is
wound wire of a suitable resistance. According to another form as hereinafter
described the core may be fixed and the solenoid be attached to the disc on the
wires. The positions of the solenoid and the core are so arranged that they shall
be directly in the field of the lines of force. This instrument can be used either as
a receiver or as a transmitter or as both. In this instrument also the sound waves
act directly on the disc or plate which supports the core or solenoid setting the
same in vibration and therefore varying the current sent into the line whereby no
tympan or diaphragm is needed
In order to clearly explain our invention and in what manner the same is to be
performed we refer to the accompanying drawing shewing different forms of our
instruments in which the same letters refer to the same or corresponding parts in
all the Figures.
Figure 1 is an elevation partly in section of a telephone shewing in what
position we may place our instrument. A is the frame hereinafter described of one
of our transmitters placed opposite the inner opening of the mouthpiece
Figure 2 is a plan of one form of our microphone transmitter. A is the frame
which may be of any convenient shape and made of any suitable metal or material
across which are tightly stretched in any convenient manner the wires B which
wires are made of any metal or material that is incapable of inductive action. On
one side of the wires B is secured a disc or plate C which is smaller than the
frame A and is made of cork wood vulcanite or other suitable material. To this
disc C are attached a number of wires or strips of platinum D or the said wires or
strips D may be attached to the suspension wires B. On the other side of the
wires B is secured a ring E of insulating material préferably caoutchouc of about
the same size as the disc C on which ring E is placed a thin disc or plate of gas
coke or carbon F and the chamber thus formed by the discs C and F is nearly
filled with granular carbon which is not shewn in this Figure. The discs C and F
and the ring E are at their peripheries firmly cemented or joined together and
made air tight and we prefer to varnish the exterior of this apparatus so that it
may be made impervious to moisture. A connecting wire from one pole of a
battery is attached to the frame A and is also in connection with the platinum
wires or strips D while the other pole is connected to a wire attached to the carbon
disc or plate F. Thus when this apparatus is placed opposite the inner end of the
mouth-piece the sound waves or vibrations impinge directly upon the cork or
carbon disc or plate and the compound disc or plate in its entirety vibrates on the
suspension wires setting up variations in the resistance between the carbon and
platinum wires or strips. An inductorium can be inserted in the circuit but
excellent results have been obtained from a direct battery current.
Figure 3 is another form of this apparatus in which the disc C herein before
described is made of carbon and the space between the discs C and F is partly
filled with granular carbon or coke or with platinum pellets small pieces of
platinum sponge or small pieces of platinum wire in any form as shewn at G.
In Figure 4 instead of the two discs herein before described we use a single plate
or block of carbon H which is slightly convex at the back thereof and is supported
in a central position in the frame A by one or more horizontal wires B' which are
also incapable of inductive action as before described. A vertical platinum wire
or strip I is secured behind the plate H to the frame A but it is insulated therefrom
which wire or strip I just merely touches the convex back of the plate H. When
the vibrations are set up in the plate H by the sound waves the said plate H
presses with greater or less force against the vertical wire or strip I thus presenting
a greater or less surface for contact by reason of the convexity of the back of the
Baid plate H
In Figure 5 instead of a single plate or block of carbon we use a number of
strips of carbon K or of other semiconductor placed side by side as shewn and
insulated from each other in their length but connected' in series in any suitable
manner at their extreme ends. These strips K can be secured together in any

page_text: convenient manner and, are suspended by the wires B stretched across the frame A
as hereinbefore described.
Figure 6 is a cross section of a transmitter formed after the manner hereinbefore
described and shewn in Figure 3 but with two sets of discs or plates. One pair
of the discs C and F are placed on either side of the suspension wires B stretched.
across the frame A: between each of which pairs is the insulating ring E whereby
the chambers are formed in which the carbon or platinum are placed as hereinbefore
described.
In all these forms as hereinbefore described the plates or discs may be smooth on.
their inner surfaces or may have any kind of corrugations or projections formed
thereon as may be deemed desirable.
Figure 7 shews one form of our magneto electric receiver. A is the metal frame
across which are tightly stretched the wires B also incapable of inductive action
on which wires B is secured the plate or disc of wood cork vulcanite or other.
suitable material L. To the plate L is fixed a short rod M of some non-magnetic
substance which carries a light iron bobbin N surrounded by a helix of insulated
wire. The core thus formed is allowed to move freely within another bobbin of
wire O. The helix on the bobbin N may be connected with an independent.
battery or may be connected with the helix on the outer bobbin O and the core is
so placed as to cut the maximum number of the lines of magnetic force. The
outer bobbin or solenoid O is in this form fixed on an adjustable frame or
otherwise.
Figure 8 shews another form of this receiver in which the outer bobbin or
solenoid O is attached to the disc L on the suspension wires B stretched across
the frame A herein before described while the inner bobbin or core N is fixed on
an adjustable frame or otherwise.
By thus making the core or the solenoid movable we obtain a greater
amplification of the sound waves and consequently a greater volume of sound.
In Figure 9 we adopt a slightly different form. P and R are two flat helices of
insulated copper wire and S is a helix of insulated iron wire. The helix P is
rigidly fixed to a plate of non-magnetic substance T while the helices R and S are
attached to wires B tightly stretched across the frame A. These helices are
placed in close juxtaposition and connected in series or the helices P and R may
be connected in series and the helix S may be connected to the poles of the
battery.
Figure 10 shews a modification of this form in which we use a disc or plate S¹ of
soft iron instead of the helix of iron wire S. In this case also the helix of copper.
wire P is rigidly fixed to the plate T while the plate S¹ and the other helix of
copper wire R are attached to the wires B as hereinbefore described. By inserting
iron cores P¹ and R' in the helices P and R the sound waves transmitted over
the line and received by both these forms of this instrument are greatly
intensified.
Figure 11 represents on an enlarged scale a receiver which has an armature V
moving freely within and in close proximity to the poles of a compound magnet W.
This armature V is wound with fine wire and may be connected either to a
battery or in series with the coils X upon the field magnets W and the said
armature V is placed in such a position as to cut the lines of magnetic force. The
armature V is fixed on a plate or disc Y of wood cork vulcanite or other suitable
material which plate or disc Y is attached to wires B stretched across the frame A
as herein before described. The magnets W are rigidly fixed to the case or other-
wise. The action of the apparatus in this form is similar to the action in the
other forms herein before described namely that on the passage of a current through
the helices the tendency evolved thereby is to draw the core into the split tube Z
each half of which tube Z forms part of the poles of the magnet W which attraction
aforesaid varies as the intensity of the current varies.
We have thus shewn the forms which we consider the best in which to construct
our improved instruments - but we would have it understood that we do not limit

page_text: ourselves.to the precise shapes or details of construction of the various part of
our instruments as shewn in the drawing for the same may be varied as may be
required in each particular apparatus without departing from our invention
though at the same time we would state that the said shapes and details as shewn
are very suitable for carrying out our objects as hereinbefore declared.
Having thus particularly described and clearly explained our invention and in
what manner the same is to be performed we would state that we claim as our
invention
1. In a microphone transmitter the attaching of the compound disc or the plate
or the series of strips which form the microphone to wires stretched tightly across
a frame which frame is so placed that the sound waves impinge directly on the
said disc or plate or strips and cause the same to vibrate on the said suspension
wires thereby creating molecular disturbance and obviating the necessity of using
a diaphragm or tension regulator substantially as and for the purpose herein before
described and set forth.
2. In a microphone transmitter the combination and use of the frame A the
suspension wires B the disc C on which or near which are the wires or strips D
the ring E the disc F and the granular carbon placed between the two discs the
whole combined and operating substantially as hereinbefore described and set
forth.
3. In a microphone transmitter the combination and use of the frame A the
suspension wires B the discs C and F the ring or rings E and the carbon or pieces
of platinum G between the said two or more discs the whole combined and operating
substantially as herein before described and set forth.
4. In a microphone transmitter the combination and use of the frame A the
suspension wire or wires B' the plate of carbon H and the platinum wire or strip I
the whole combined and operating substantially as hereinbefore described and
set forth.
5. In a microphone transmitter the combination and use of the frame A the
suspension wires B and the strips of carbon K connected in series the whole
combined and operating substantially as herein before described and set forth.
6. In a magneto electric receiver or transmitter the attaching of the cores or
solenoids to discs or plates fixed on wires stretched tightly across a frame whereby
the variations of the currents caused by the vibrations set up in either of the said
cores or solenoids are much intensified and the necessity of using a diaphragm or
tympan is obviated substantially as and for the purpose herein before described and
set forth.
7. In a magneto electric receiver or transmitter the combination and use of the
frame A the suspension wires B the plate or disc L the core N and the fixed
solenoid O the whole combined and operating substantially as herein before
described and set forth.
8. In a magneto electric receiver or transmitter the combination and use of the
frame A the suspension wires B the plate or disc L the solenoid O and the fixed
core N the whole combined and operating substantially as hereinbefore described
and set forth.
9. In a magneto electro receiver or transmitter the combination and use of the
frame A the suspension wires B the plate T and the helices of wire P R and S
with or without cores of iron in the helices P and R the whole combined and
operating substantially as hereinbefore described and set forth.
10. In a magneto electric receiver or transmitter the combination and use of the
frame A the suspension wires B the plate T the helices of wire P and R with or
without their cores P' and R' and the plate S' the whole combined and operating
substantially as herein before described and set forth.
11. In a magneto electric receiver or transmitter the combination and use of the
frame A the suspension wires B the disc or plate Y the armature V on the said
disc or plate Y and the fixed compound magnet W with the coils X thereon the

page_text: whole combined and operating substantially as hereinbefore described and set
fortb.
In witness whereof we the said Edgar George, Francis Agnew Pocock, John
Saunders Muir, and John Saunders Muir, Junior have hereunto set our hands and
seals this third day of September in the year of our Lord one thousand eight
hundred and eighty three
EDGAR GEORGE
(L.S.)
FRANCIS, AGNEW, POCOCK
(L.S.)
JOHN SAUNDERS MUIR
(L.S.)
JOHN SAUNDERS MUIR JUNIOR
(L.S.)
EDGAR GEORGE
(L.S.)
FRANCIS, AGNEW, POCOCK.
(L.S.)
JOHN SAUNDERS MUIR
(L.S.)
JOHN SAUNDERS MUIR JUNIOR
(L.S.)