Year: 1888

page_text: I, THOMAS LAURIE of Wellside Terrace, Falkirk, in the County of Stirling, North
Britain, Electrical Engineer do hereby declare the nature of this invention to be as
follows:-
This Invention, which relates to improvements in telephonic apparatus, has reference
to the transmitters and receivers thereof as well as to the signalling used in or with
telephones.
According to the present improvements in transmitters, the electrodes are all
situated loosely, that is to say in a free state within the transmitter. The lower
electrode consists of two pieces of carbon which constitute a disc with a recess in its
centre. This recess may either be a complete hole or it may be closed at its
bottom. The two pieces constitute a disc and have a layer of fibre or other insulator
between them. The hole or recess in the dise may or may not be fluted and upon
or in the hole or recess there is laid a ball or other suitably shaped piece of carbon
which constitutes the upper or other electrode. Both electrodes are so contained
within the case or receptacle of the transmitter, that the sound waves of the speaker's
voice have free access to them.
In place of using a ball or other equivalently shaped piece of carbon for the
upper electrode, pencils of carbon suspended at their upper ends may be substituted,
the lower extremities of these pencils of carbon bear against any suitable part of
the lower electrode in such way that when the transmitter is spoken into the
points or lower extremities of the pencils rub against or move upon the surface of
the lower electrode.
In place of using the pencils last described or the ball or equivalently shaped
piece of carbon herein previously referred to, the upper electrode may consist of
particles of carbon which rest in the recess or upper surface thereof and are set
in motion with the lower electrode by the action of the speaker's voice.

page_text: place of forming the lower electrode as hereinbefore described, the upper and
lower electrode may respectively be formed of pieces of carbon whose area or
superficial extent is greater than a semi-circle. These two portions are respectively
checked out at their centre parts so that one overlaps the other whereby the
contact surfaces or points of each are caused to have the necessary rubbing motion
upon each other when vibrated by the sound waves of the voice of the person speaking
into the transmitter, and in place of two such pieces of carbon one overlapping the
other, several such pieces like pencils of carbon similarly overlapping and resting
one upon the other may be arranged in parallel series side by side within the
transmitter.
In
A modification of the foregoing improvements consists in keeping the ball or
equivalently shaped piece of carbon out of contact with the lower electrode.
this case a horizontal bar of carbon is passed through the ball, the ends of which
bar rest on the lower electrode, the ball in this case may be made either of carbon
or other material and in place of forming the dise of the transmitter, in which the
upper electrode rests, of carbon, it may be formed of wood or other suitable material
and have three or more points of carbon held in it and which constitute the lower
electrode upon or against which the upper electrode rests.
It is to be understood that in place of carbon the electrode may be constructed
of platinum or other good conductor of electricity and it is explained that when
suspended pencils of carbon are used, the best result is obtained by forming their
edges or points of contact with the other electrode into extremely thin or fine edges
or hearing points.
The improvements, which relate to the receivers in telephonic apparatus, have for
their object to overcome a certain defect due to atmospheric changes which occur in
membrane diaphragms used in such receivers. The defect here referred to is that due
to alterations in the state of tension of the membrane diaphragm caused by variations
in the amount of moisture contained in the atmosphere and in cases where one
instrument is used both as a receiver and transmitter this defect being in such case
also caused by the tension of the membrane diaphragm becoming altered by the
action upon it of the moist breath of the speaker, this part of the improvements has
also for its object to correct the variations in tension of the membrane diaphragm due
to this cause also.
The improvements consist in causing one face of the membrane diaphragm to bear
against a ring having a V-shaped or an equivalent edge equi-distant from its centre
and against which the diaphragm is pressed with a practically constant degree of
tension by the action of springs, thus any variation due to differences of moisture
acting upon the diaphragm are taken up by the elastic pressure of the springs
stretching the membrane diaphragm over the V-shaped or equivalent edge of the
aforesaid ring.
Another improvement relating to telephonic receivers has for its object to enable
the relationship of the soft iron disc carried at the centre of the membrane diaphragm
and the soft iron core of the magnet against which it operates to be always capable
of being inspected without removing the cap by which these parts are enclosed. This
consists in forming a hole at opposite sides of the cap and casing so that on being
held up to the light the position or relationship of the disc on the membrane to the
soft iron core can be seen and necessary adjusted.
Another improvement in connection with telephonic apparatus relates to that class
of telephones in which a constant current is maintained in the line and it has for its
object to prevent confusion in signalling. In telephonic apparatus of this kind when
the receiver is unhooked from the instrument it causes a single stroke of the bell on the
instrument at the other end of the line which might cause a person at that end to
suppose that he was being called to the telephone when such would not really be the
case. To make it sure to such person when his attendance at the telephone is
required the line at the transmitting end is provided with an apparatus for making and
breaking contact intermittently and when the person at the transmitting end desires
to speak with the person whose telephone is placed in connection with him at the

page_text: other end the person at the transmitting end operates the apparatus for intermittently
making and breaking contact thereby transmitting a series of intermittent signals
to the opposite end the intermittent character of which conveys to the person at that
end that his attendance at the telephone is being called.
Dated this 12th day of March 1883.
ST. JOHN V. DAY,
115, St. Vincent Street, Glasgow,
Petitioner's Agent.
Improvements in Telephonic Apparatus.
I, THOMAS LAURIE of Wellside Terrace, Falkirk, in the County of Stirling, North
Britain, Electrical Engineer do hereby declare the nature of this invention and in what
manner the same is to be performed, to he particularly described and ascertained in
and by the following statement:-
My Invention, which relates to improvements in teleplionic apparatus, has reference
to the transmitters and receivers thereof as well as to the signalling used in or with
telephones.
In order that my Invention may be properly understood and readily carried into
effect. I have hereunto appended two explanatory sheets of drawings, in the several
Figures of which corresponding parts are marked with the same letters of reference.
In Figure 1, the ball A of carbon or other suitable material is laid loosely in the end
of an aperture T, connected with a suitable mouthpiece. Above the ball A, two
pencils B, B. of carbon or equivalent material are suspended loosely at D, D, and at
such a slight angle that the lower ends of the pencils 13, B, rest lightly against the
ball A. The action of this apparatus is as follows. When any sound waves enter.
the aperture T, the ball A, is rapidly oscillated or otherwise mechanically disturbed
on the edge of the aperture T, constituting its seat. This movement or disturbance of
the ball causes it to rub against the pencils B, B, and to correspondingly put them
into a state of motion giving the desired variation of current passing through these
electrodes necessary for the transmission of sound when this arrangement of the
electrodes is used as the transmitter of a telephonic circuit one wire is carried from
the pencils B, B. and another from the ball A, or one wire may be carried from each
of the pencils B, B, the ball completing the circuit.
At Figure 2, is shewn a modification of the arrangement herein before described with
reference to Figure 1, in which instead of the ball A, the lower electrode is a conical
piece of carbon A, having flutes or grooves in its conical surface, this surface being

page_text: shaped like what is commonly known as a rosedrill. The lower cylindrical part of
the electrode A, is inserted loosely into the tube or aperture T, and above the lower
electrode A, a carbon pencil or pencils B, B, constituting the upper electrode is or are
suspended loosely at D, so that their lower ends bear lightly against the lower
electrode A. When the voice or other sound waves strike or impinge against the
-lower electrode A, it is correspondingly oscillated rapidly on its seat and by this
action varies the inclination of the pencil or pencils B, B, by rubbing against them.
When used as a telephonic transmitter one wire of the circuit may be connected to
the lower electrode A, and the other to the carbon or equivalent pencil or pencils B.
In this arrangement it is preferred that each pencil at the part where it rests against
the conical part of the lower electrode A, should be hollowed or scooped out so that it
may make contact with more than one of the V-shaped projections formed by the
flutes or grooves in the lower electrode. The electrode A, in place of being fluted
as shewn may be left with a plain surface and the pencils B, B, may be fluted where
they rest on the lower electrode A.
At Figures 3 and 4, there are shewn in end elevation and front elevation respectively
another arrangement of moveable electrodes. This consists of one or a series of
triangular or wedge-shaped blocks A, hinged at H, by metal, cloth or other suitable
material above the aperture T, and which constitute the lower electrode or electrodes.
Above this block or blocks A, one or more pencils B, is or are suspended loosely at D,
so that the lower ends of these pencils rest lightly against the inclined face of the
block or blocks A. The pencil or pencils B, constitute the upper electrode or
electrodes when sound waves from the voice or other source pass into the aperture T,
they strike against the triangular block or blocks A, and putting it or them into rapid
motion that motion is transmitted to the pencil or pencils B, and thus the lower ends
of the pencil or pencils B, rub against the block or blocks A, and act in the manner
hereinbefore set forth. When used in a telephonic circuit one wire is connected to
the block or series of blocks A, and the other wire is connected to the pencil or
pencils B, as shewn.
At Figure 5, is a side elevation of another modification of electrodes for telephonic
transmitting apparatus both of which are moveable. In this arrangement the
triangular or wedge-shaped block or blocks of carbon A, is or are hinged or suspended
by metal, cloth or other suitable material at H, near to the upper part of the
aperture T, and against the block or blocks A, the pencil or pencils B, rest lightly,
being suspended at D. When sound waves pass into the aperture T, they set the
block or blocks A, into rapid motion upon the hinge or suspender D, and this
communicates a corresponding motion to the pencil or pencils B, so that the lower
ends of these pencils and the inclined face of the block or blocks A, rub against each
ther in the manner necessary, as herein before set forth. When the electrodes A
and B, are used in the transmitters of a telephonic circuit, one wire is or may be
connected to the block or blocks A, and the other to the pencil or pencils B.
At Figure 6, is shewn another modification of electrodes for telephonic transmitting
apparatus shewn at and hereinbefore described with reference to Figure 5. In this
case the wedge-shaped or triangular block or blocks A, is or are placed in the reverse
position to that which the said block or blocks occupy in Figure 5, that is to say,
whilst in Figure 5, the block or blocks A, is or are hinged to the aperture T, at their
narrowest end which is in this case placed uppermost, in Figure 6, the block or
blocks A, is or are hinged or suspended at their thickest end which in this case is
placed uppermost.
At Figure 7, there is shewn a complete transmitter constructed according to my
Invention. The transmitter is mounted in a block W, of wood, metal, or other suitable
material. The carbon block or series of carbon blocks A, is or are hinged or
suspended at. their upper ends to a washer B', of rubber, cotton, wool, or any other
suitable material or the block or blocks, A may be hinged directly on the aperture or
mouthpiece without the washer intervening. This washer is or may be attached to
the mouthpiece S. The carbon pencil or pencils B, is or are suspended from a bar R,
of rubber, metal, or of any other suitable material. The pencil or pencils B, rests or

page_text: rest lightly against the blocks or series of blocks A. The mounting may be provided
with a cover C, for the purpose of keeping out dust and preventing interference with
the internal parts. A spiral spring X, and a regulating screw F, are provided and
fixed to the suspending bar R, for the purpose of giving the desired inclination to the
pencil or pencils B. The block W, may be suspended with India-rubber to keep it
free from outside noise so that no extraneous sound or vibration of any other material
to which the said block W, may be attached shall interfere while the mouthpiece S, is
being spoken into or it may be held in the hand while using it. One wire of the
telephonic circuit is connected with the block or blocks A, as shewn at H, and the
other is connected to the pencil or pencils B, as shewn at I, and both are connected to
the binding screws L, L. which form part of the circuit as shewn in drawing which
are insulated from one another.
Figure 8, is another modification of my improvements in transmitters B, B, are two
carbon or other equivalent pencils loosely suspended at D, D, and resting at a slight
angle against the conical hole C, in the lower electrode. The sound waves being
directed on the underside of the paris A, and B, at T, (which parts are either united
by the insulating strip D, or hinged at their outer corners H, in the manner before
specified) causes the parts A, and B, to rise rapidly up and down and consequently
produces a rubbing action between the pencils B, B, and the parts A, and B. This
alters the inclination of the pencils and produces the necessary variations in the
current.
Figure 9, shews another arrangement of my improved transmitter indicating
how the sound waves may be made to impinge against the pencil or pencils B, in
place of against the block or blocks A. Both the pencil or pencils B, as well as the
block or blocks A, are suspended at D, and H. One wire of the telephonic circuit is
connected to the suspending point D, and the other wire is connected to the suspended
point of the electrode or electrodes A.
Figure 10, is another modification of my improvements in transmitters shewing
how in place of a suspended pencil a light carbon ball or balls may be adopted. The
ball or balls E, is or are suspended by a very light metallic wire from the point D, or
it may be suspended by a light thread or similar material but a thin wire is preferable
in so far as it is thus capable of being used as the conductor. The action is
as follows: When the block or blocks A, is or are actuated by the sound waves as
before described with reference to Figure 5, the ball or balls B, are made to rub or
roll against the block or blocks A, producing the necessary movement of the electrodes.
On wire of the telephonic circuit is connected to the point of suspension D, when a
metallic wire is used and the other wire of the circuit is connected to the point
of suspension H.
A modification of the foregoing improvements consists, instead of having all the
electrodes of carbon, one of the electrodes may be of platinum or other conductor of
electricity and it is explained that when suspended pencils of carbon are used,
the best result is obtained by forming their edges or points of contact with the other
electrode into extremely thin or fine edges or bearing points.
It is to be understood that it is not essential that the pieces constituting the
electrodes A, and B, or the block or blocks A, of my Invention should be solid at
that part where the sound waves strike or impinge against it or them, it is indeed
preferable to have these parts perforated in order that the sound waves may not strike
too violently against them. It is also to be further understood that I do not confine
myself to the exact manner specified of electrically connecting the electrodes as this
may be done in a variety of ways all well known nor to the number of electrodes
specified as more may be joined up with advantage.
The improvements which relate to the receivers in telephonic apparatus, have for
their object to overcome a certain defect due to atmospheric changes which occur in
membrane diaphragms used in such receivers. The defect here referred to is that due
to alterations in the state of tension of the membrane diaphragm caused by variations
of the amount of moisture contained in the atmosphere and in cases where one
instrument is used both as a receiver and a transmitter this defect being in such case

page_text: also caused by the tension of the membrane diaphragm becoming altered by the action
upon it of the moist breath of the speaker, this part of the improvement has also for
its object to correct the variations in tension of the membrane diaphragm due to this
cause also. The improvement consists in causing one face of the membrane diaphragm
to bear against a ring having a V-shaped or an equivalent edge equi-distant from its
centre and against which the diaphragm is pressed with a practically constant degree
of tension by the action of the springs, thus any variation due to differences of
moisture acting upon the diaphragm are taken up by the elastic pressure of the springs
stretching the membrane diaphragm over the V-shaped or equivalent edge of the
aforesaid ring.
Another improvement relating to telephonic receivers has for its object to enable
the relationship of the soft iron disc carried at the centre of the membrane diaphragm
and the soft iron core of the magnet against which it operates to be always capable of
being inspected without removing the cap by which these parts are enclosed. This
consists in forming a hole at opposite sides of the cap and casing so that on being held
up to the light the position or relationship of the disc on the membrane to the soft
iron core can be seen and if necessary adjusted. Another improvement in connection
with telephonic apparatus relates to that class of telephones in which a constant
current is maintained in the line and it has for its object to prevent confusion in
signalling.
At Figure 11, is shown a vertical section of one form of receiver constructed
according to my Invention and Figure 12, is a plan of the same. A, A, is a circular
frame of metal or other suitable material with a raised ridge or ring B, all round,
over which the membrane diaphragm, is stretched. The diaphragm consists of a
membrane of parchment or other suitable material, clamped, cemented or held between
two rings D, D, of metal or other suitable material. In the centre of the said membrane
diaphragm is cemented or otherwise secured a thin piece or disc of iron or steel I.
The diaphragm is placed so that the ridge B, B, is pressing against the said
diaphragm all round its circumference. One ог more regulating screws E,
are inserted loosely through the rings D. D, and screwed into the lower
frame A, A. Between the rings D, D, and the head of the screw or screws E, a
spiral or other spring F, is inserted so that when these screws are tightened or
screwed down, the spiral or other spring will press against the said rings and by
that action cause the surface of the diaphragm C, to be always in a distended state.
Should the membrane diaphragm C, become slack by any variation of atmosphere
or other influence the spiral springs F, will by their pressure against the rings D, D,
take up any slackness that may occur in the said diaphragm or vice versa. Should
any tightening of the diaphragm take place through atmospheric or other
influence the springs F, will correspondingly yield thereto. By this improvement
the diaphragm C, is always kept in an almost equal state of tension so that the core
of the electro-magnet. H, may be as near as possible without danger of coming in
actual contact with the said iron dise 1. The magnet H, is supported by its core to
the horizontal bar of iron J, or other suitable material, which slides up and down the
standards M, M. The said bar, core and magnet being regulated and kept at their
proper position by the regulating screws K, K, and spiral or other springs L, L.
This form of a receiver I prefer to fit into a suitable case which may be fixed to a
wall or other support and the emitted sounds carried by means of one or more flexible
tubes fitted into the socket N, to the ears of the person listening or attending.
Figure 13, shews another form of receiver suitable for holding in the hand. The
diaphragm C, is fastened and stretched on the cap A, which is screwed on to the
holder B, B. The magnet H, is kept in position by means of the regulating
screw D, and the rubber washer spring D, or by a metal or other suitable spring.
The conducting wires are carried to the terminals E, and covered with a cap F
through which the conducting cords G, are continued to the other parts of a
telephonic instrument. As a means of regulating to a nicety the distance of the
magnet core from the iron disc on the diaphragm C, I bore two holes F, F, on
opposite sides of the cap or case A, and B, so that when held up to the light and
:

page_text: looking into one of these holes the magnet core will be observed obstructing the
light of the other hole, so that the distance between the disc and magnet may be
easily seen and regulated accordingly.
be
Figure 14. shews an arrangement for calling attention to a telephonic instrument
of that class where a battery current is used in the line wire when speaking. In
the ordinary method adopted, a trembling hell is invariably used so that if the
receiver at one end be off the usual hook switch and the receiver at the opposite end
be on the hook of a similar switch it will, if the battery be strong enough, keep the
bell at the said opposite end ringing so that when a conversation may
desired both operators may not simultaneously put their receivers on their switchers
and accordingly the one that has his receiver on first receives a current through his
bell which may be understoood as another call when it is not the case and
is liable to cause confusion. By my improvement I adopt, single stroke bells and a
call is made by turning the toothed wheel A, by a suitable handle, the teeth of this
wheel coming in contact with the spring B, will cause it to press against the stud G,
which is connected to ene end of the battery. Every time this spring is made to
press against the stud C, a current is sent into the line causing one stroke of the
single stroke bell at the other end of the line and if the wheel be rotated smartly an
intermittant or trembling ring will be made. On the other band should one operator
take his receiver off the hook of the switch a current will be sent into the line but
will only give the bell a single beat and by this means a decided call can easily be
detected from a ring caused by the lifting off, of a receiver or by not replacing
receivers at both ends of the line simultaneously.
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 :-
1. The several arrangements of electrodes for telephonic transmitters, as shown
respectively at Figures 1, 2, 3, 4, 5, 6, 8, 9 and 10, of the annexed drawings,
substantially as hereinbefore described.
2. The arrangement wherein one or more of the electrodes is or are notched or
Aluted, substantially as hereinbefore described and shewn on the annexed drawings.
3. The general arrangement and construction of transmitter as shewn
Figure 7, of the annexed drawings and wherein the upper electrode B, is carried
upon an adjustable regulating bar R, substantially as hereinbefore described.
IL
4. In telephonic receivers the arrangements whereby the diaphragm C, is
maintained in a constant state of tension by being stretched by the action of springs over
the narrow edge of a circular ring substantially as hereinbefore described and shewn
at Figures 11, 12, and 13 of the annexed drawings.
5. The constructing of the case of telephonic receivers with spy holes for the
purpose of inspecting by the eye the relative positions of the electro-magnet and the
circular plate carried on the diaphragm, substantially as herein before described and
shewn at Figure 13, of the annexed drawings.
6. The arrangements shewn at Figure 14, of the annexed drawings for the
purpose of preventing confusion in signalling substantially as herein before described.
Dated this 12th day of December 1888.
ST. JOHN V. DAY,
115, St. Vincent Street, Glasgow,
Applicant's Agent.