TELEPHONIC TRANSMITTING INSTRUMENTS OR VALVE TELEPHONES
Year: 1884

page_text: DEMVIRICATION.
SILVANUS PHILLips Thompson, of University College, Bristol, Doctor of Science
and Professor of Experimental Physics, and PHILIP JOLIN of 2 Elmdale Rd
Redland, Bristol, Engineer do hereby declare the nature of this our invention for
TELEPHONIC TRANSMITTING INSTRUMENTS OR VALVE TELEPHONES to be as
follows:-
Our invention relates to a novel kind of Telephonic transmitting instrument
which we construct upon the following plan. In most of the forms of Telephonic
transmitter hitherto known one or both of the electrodes have been attached to
springs or to a tympanum or diaphragın, or to soine attachment capable of taking
up vibrations imparted by means of a tympanum or diaphragm, but in our new
telephonic transmitter the working parts are constructed as a valve, for example
one of the electrodes or contact pieces forming the valve-seat and the other the ball,
plug, flap or other portion of the valve resting under normal conditions upon its
sent, and so arranged that the sound-waves of the voice tend to open the valve,
raising the ball, plug, or flap more or less completely from its seat and letting it
fall again. By this invention we are able to simplify and cheapen the construction
of telephonic transmitters, and to construct them of fewer parts than heretofore.
It is not necessary in our transmitters that the valve should be entirely closed when
in their normal state and in some cases apertures are expressly bored to prevent
the descent of the valve into its seat from closing absolutly the air-ways. Nor is
it necessary for the valve itself to be an electrode; for the instrument may be made
equally efficient if the valve-seat be divided into two or more parts separated by
wood or other non-conducting material, one part or segment of the seat forming
one electrode, the other part or segment forming the other electrode, and the valve,
made also of suitable conducting material forming contact between the two
electrodes. And it is further convenient, in some cases where the transmitters are
required to carry strong currents, to provide for more electrodes than two. In such
a case the valve seat may be divided into four or more separate parts or portions
each of which is separated from the others by non-conducting material, two or
more of the electrodes being made positive electrodes and the rest serving as
negative electrodes. The sound-waves of the voice must impinge upon the valve,
and they may strike either upon its upper or upon its lower surface, or upon both.
When it is desired to make the air-waves produce a more powerful effect, they may

page_text: be concentrated upon the valve by a speaking-tube or other suitable mouth-piece.
As to the material of the electrodes or contact pieces of the valves or valve seats
they may be made of any sufficiently good conductor of the kinds available for the
making of microphones or telephonic transmitters, as for example of any good-
conducting non-metallic substance, such as coke, which can be made up in the
shape of a clack, plug, ball, frustrum of a cone, zone of a sphere, or other suitable
form for a valve of the common kind. The valve is in some cases made of wood
or other non-conducting material and the electrodes or contact pieces are arranged
at the top or side of it so that when the air-waves tend to open the valve to a
greater or lesser degree the valve in turn tends by the motion which it imparts to
the electrodes or contact-pieces to open to a corresponding degree the electric-
circuit, and thereby affect the quantity of electric-current which flows through the
electrodes. In some cases in which the valve is itself an electrode we make the
seat of non-conducting materials, serving merely as a support for the valve and for
contact-pieces or electrodes applied at the sides of the valve, such contact pieces or
electrodes being carried from the centre or valve-piece to the other pieces placed
round' the framing. In this particular way of arranging the connections of the
parts the valve-piece which covers wholly or partially the opening in the sent
receives the impulses of the sound waves and tends to rise up and sink down in its
seat, and, consequently moves the contact pieces or electrodes in a manner corre-
sponding to the impulses of tho sound-waves, causing them to open the circuit to a
greater or lesser degree. When strong currents are to be transmitted, in order to
prevent undue sparking several valves may be used at once, cach consisting of a
hall, plug, clack or other suitable piece resting on its own sent, and serving ns
electrodes or as means of actuating electrodes or contact-pieces, the sound waves of
the voice being divided simultaneously upon the several valves, which, since each
of them receives a part of the current, simultaneously act upon their own part of
the current, and set up in it the requisite fluctuations corresponding to the opening
Or to effect this end
of the valves to a greater or lesser degree by the air waves.
still more effectually the valve-piece itself may be divided by non-conducting
material into several parts, cach being in contact with a soparate part of the valve
When such dispositions of
sent or with other suitable contact-piece or electrode.
the parts as are last described are adopted it is found convenient to apply to the
valve-pieco or valve-pieces small weights or springs to keep them in their places
and in some cases in order to ensure that the complete opening of the circuit neve
occurs, a proper contact is obtained by the use of wires, springs or of mercury cups
And we find that when weaker currents are to be transmitted in single-valv
transmitters, if the valve-piece is light, a small weight or spring is advantageously
applied to keep the valve-piece from leaving its seat A plug-valve or piston-valv
which is set within its tubular seat but does not rest thereon can be used when the
electrodes or contact-pieces are placed above or at the sides of the valve or betwee
the top of the valve and its framing. Or, when the valve has a tail it is convenien
to arrange the electrodes or contact-pieces so that they shall be actuated by th
movements of the tail of the valve, or the valve-tail itself may be one of the tw
electrodes.

page_text: COMPLETE SPECIFICATION.
We, SILVANUS PHILLIPS THOMPSON, of University College, Bristol, Doctor of
Science and Professor of Experimental Physics, and PHILIP JOLIN, of 2 Elmdalo
Road, Redland, Bristol, Engineer, do hereby declare the nature of our invention
for
"TELEPHONIC TRANSMITTING INSTRUMENTS OR VALVE TELEPHONES" and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :—
Our invention relates to a novel kind of telephonic transmitting instrument, of
the class in which the air-waves act directly upon the current-regulator, without
any tympanum or diaphragm, which we construct as hereinafter described.
The sound-waves formed by the voice are suitably directed by means of a mouth-
piece, mouth-tube, or reverberator and caused to pass upwards through an orifice
and impinge upon a free piece which we term a valve. The valve rests freely over
or upon the orifice and its weight is supported by a suitable piece or pieces, which
we may conveniently term the valve-seat. The action of the sound-waves upon
the valve produces variations in an electrical current in the manner requisite to
transmit sounds by electricity as hereinafter described.
Where a tympanum, diaphragm, reed, tongue, or other piece confined at one or
more points and capable of vibratory motion is used to take up the sound-waves
produced by the voice, a considerable part of the effective energy of the sound-
waves is rendered unavailable or ineffective for the reproduction of sound by being
absorbed in bending or deforming the confined vibrator. Furthermore, the
resistance which such confined vibrator offers to the sound-waves causes a con-
siderable portion of them to be uselessly reflected back. Moreover secondary
vibrations of such confined vibrator are produced, which muffle the sounds and
impair the distinctness of the articulation.
Where the sound-waves aro caused to compress a "tension-regulator" or current-
regulator, a further amount of their available energy is uselessly absorbed by such
compression and appears in the form of heat in the regulator.
Where the requisite adjustment of the regulator is obtained by screw or other
similar pressure, variations of temperature, causing expansion and contraction of
the parts of the instrument, interfero with the adjustment and produce irregu-
larities in working, and this objection applies to many existing forms of instru-
ments.
We are aware that instruments have been heretofore made, or proposed to be
made, in which some of the above mentioned defects have been obviated, but the
transmitting instrument which is the subject of our invention combines the
following advantages. By the use of the free piece which we term a valve, capable
of a motion of translation as a whole, without deformation, no resistance is opposed
to the sound-waves, such as comes into play when a confined piece or vibrator of
the character above referred to is used, and therefore the waste of energy due to
bending or deformation, or to reflection of the sound-waves, is obviated or
minimized. Furthermore, no secondary vibrations interfere with the distinctness
of articulation. Also in our arrangement loss of energy from compression of the
regulator or other parts of the instrument is avoided. Our arrangement is also
such that variations of temperature do not affect the adjustment of the instrument.
A further general advantage of our invention is that the construction of telephone
transmitters is thereby considerably simplified and cheapened.
The free piece hereinbefore referred to we have termed a valve from its general
imilarity in form, position, and capability of motion to an ordinary valve used to

page_text: allow a fluid to pass through a chamber in one direction, but to prevent its flow in the
other direction. By the use of this term we do not intend to imply that our valvo
is similar in its mechanical functions to an ordinary valve, but only that it is similar
in form, position, and capability of motion. We are aware that other arrangements
of telephone transmitters have been heretofore proposed in which the current- 5
regulator has consisted of a loose piece or block or sphere of conducting material
supported by, and making electrical connection between, two or more other pieces
or blocks of conducting material. But these arrangements differ from ours in the
mode in which the sound-waves are communicated to the current-regulator, and we
wish it to be clearly understood that the direct communication of the motion of 1
the air-waves to the free piece or valve as herein described in such a manner that,
under the increment of pressure due to the air-waves, the valve is free to rise from
its seat, is of the essence of our invention.
Figures 1 and 2 illustrate a simple form of our valve telephone.
a is the valve which consists of a suitably shaped block or cake of suitable
conducting material, supported upon the valve-seat b, which is a ring of suitable
conducting material over the orifice of the tubular cavity & in the block B, the
sound-waves being directed upwards through the tube d. If the weight of the
valve be insufficient to secure the requisite contact between valve and seat, the
valve may he furnished with a stalk or tail-piece e and a small weight at the end
thereof. A light and flexible wire c is connected to the valve so that the said valve
forms one electrode, the sent forming the other electrode. The sound-waves will
'tend to lift the valve from its seat and let it down again, thereby varying the
electric current in the requisite manner, The wire c may be connected to the tail-
piece of the valve, as in Figure 3.
We have shown the valve of a spherical form, and this form possesses the
advantage of being self-adjusting upon its seat and requiring no guidance. But
we do not confine ourselves to the use of this form of valve, as other forms, such as
a segment of a sphere, or frustum of a cone, may be used.
As above described, the valve forms, or is part of, one electrode and the seat
forms the other electrode; we prefer, however, to divide the seat into two or more
parts or segments insulated from one another, as illustrated by Figures 4, 5 and 6.
In these cases, instead of using the valve as an electrode we use one part or parts.
of the seat as one electrode and the other part or parts of the seat as the other
electrode, the valve in this case completing the circuit between the two electrodes.
(Figure 4 also illustrates a convenient mode of fitting up our valve telephone).
In some cases, we find it advantageous to use two or more valves upon the
circuit in one transmitter, as illustrated in the case of divided seats in Figures 7, 8
and 9. If it be desired to augment the magnitude of the variations of the electric
current, we may connect the electrodes in series as shown in Figures 7 and 8. If,
on account of the strength of the current, it be desirable to take precautions against
sparking, we may connect the electrodes in multiple arc as shown in Figure 9.
We can also attain similar results by using a divided scat such as is shown in
Figures 5 and 6 and employing therewith a valve divided into corresponding
insulated segments. Each section of the valve will thus act in conjunction with a
section of the soat, and we may connect these soctions either in series or in multiple
are as before mentioned.
We find that a tube and mouth-piece, such as is described in the specification of
former Letters Patent dated August 9th, A.D. 1882, Nº 3803, forms the best and
most convenient method of concentrating the sound-waves upon the valve, but the
ordinary conical mouth-piece may, in some cases, be used for this purpose without
a tube, though less advantageously, but it should be sufficiently deep or long to
catch any moisture from the breath of a person speaking into the transmitter
which might otherwise settle upon the contacts. Also, instead of conducting the
sound-waves to act upon the valve by means of a tube, we may make use of a
suitable reverberator or sound-reflector as indicated in the said former specification,
A suitable arrangement for this purpose is shown in Figures 10 and 11,

page_text: The above arrangements have been described as if the valve completely closed,
the orifice of the valve-seat, but this is not necessary. Apertures may be left in
or around the seat so that the valve, when resting upon its seat, does not completely
prevent the passage of air along the tube. For instance, in the arrangements
illustrated in Figures 8 and 9, the spaces between the divided portions of the seat
may be left open; or narrow apertures or air-spaces may be made round or through
the seat. One arrangement in which air can pass the valve, and which possesses
an additional advantage of anothor kind, is illustrated with reference to the sphere
form of valve in Figures 12 and 13. It is well known that, when two rigid bodies.
are in contact, three points of contact determine their approximation one to another,
whilst if it be attempted to produce a contact in four points an element of instability
is introduced. For instance, a three-legged table always stands firm, even on an
unlevel floor, whilst a rigid four-legged table will not stand firm, if the floor be
level, unless the extremities of the legs are all in one plane, or on an unlevel floor,
unless the fourth leg be of such length as to reach the ground at the point where it
should stand. Applying this principle to our valve telephones, we find it to be
very advantageous to seat the valve upon three pins of suitable conducting
material, as shown in elevation in Figure 12 and in plan in Figure 13. By this
means, the element of uncertainty in the action of the telephone, due to the
variation of the contact-points of valve and seat, which is introduced if the
surfaces are not fitted with mathematical accuracy, is eliminated. The pins should
project above the orifice of the tube, so, that the valve may be slightly raised above
such orifice, leaving a narrow space between the valve and the edges of the orifice
about the width of the thickness of a sheet of paper. This form of valve-seat may
be applied with advantage to valves of other than a spherical shape. The pins may
be adjustable, if desired, and may be made of metal tipped with gold, platinum,
iridium, or other infusible metal or conducting material. As before described, tho
valve has been, in all cases, placed at the end of the tube, but the valve may also,
with less advantage, be placed within the tube or an oxtension thereof, as illustrated
in Figures 14 and 15. In such cases, the valve should be somewhat smaller than
the upper portion of the tubo.
The conducting material used for the contact-pieces may be such as is available
for similar purposes in microphones or telephone transmitters of known con-
struction, as for example any non-metallic substance, such as coke, which is a
sufficiently good conductor, and which is capable of being made up into the desired
form of valve. In many cases, we find that a metal or metalloid or alloy, answers
the purpose as well as, and, in some cases, better than, any non-metallic body;
and, in particular, we have found that phosphor bronze, silicium bronze, selenium
bronze, tellurium bronze and sulphur bronzo give good results. But we wish it to
be understood that we do not limit the application of our invention to the use of
any particular material for the contact-pieces.
The valve may be either solid or hollow, but we prefer to make it hollow. In
this case, we find it very advantageous to carry the stalk through the valve and to
secure the stalk rigidly to the surfaces of the valve where it passes through the
same, as shown in Figure 16, where the stalk is secured at the points m and n,
thus acting as a stay and helping to prevent the walls of the ball from entering
into vibration.
It will be observed that we arrange the valve relatively to the direction of
motion of the sound-waves so that the increment of pressure due to the sound-
waves tends to lift or remove the valve from its seat, although the lifting of the
valve should only take place to an infinitesimal extent. With this arrangement, the
valve being free to move, as a whole, away from its seat, the motion or tendency of
motion of the valve is simply one of translation, without deformation or change of
shape, whence result the advantages in the utilization of the energy of the sound-
waves hereinbefore pointed out. The seat should be of such a form and so placed
that it may not to any appreciable extent enter into vibration under the influenco

page_text: of the sound-waves, so that the whole available energy of the sound-waves may be
as far as possible concentrated upon the valve alone.
We will now proceed to describe the transmitter shown in Figures 12 and 13,
which embodies the principles of our invention in a very convenient form, and in
that form which we have found to give the best results in practice. In this
instrument, the valve and valve-seat are carried by a cylindrical block B of wood
or other suitable material. The block B passes, without touching, through a
circular aperture formed in the bottom of the box or case A. The block B is
supported and maintained in its position by two annular pieces or rings e and e¹ of
india-rubber or other equivalent dampening material, which encircle the said block I
and prevent vibrations of the box or case from affecting the working parts. D is a
tube of brass or other suitable material, which is situated within a cylindrical
cavity extending axially through the block B. The tube D fits closely the lower
part of the said cavity, but there is an annular air-space between the tube D and
the upper portion of the inner surface of the block B. The tube D is of such 1
length that its upper end is somewhat below the upper end of the block B which
encircles it.
1
The valve a is seated upon three pins f.f¹, f' inserted in the upper portion of
the block B. These pins should touch the sphere or ball a at three points, which
preferably are equidistant, in a horizontal plane cutting the said sphere at a point
below its centre. These pins are preferably tipped with gold, platinum, iridium, or
other non-fusible metal or conducting material. The pins f¹, ƒ are connected
together to form one electrode, and the third pin forms the other electrode.
Upon the lower end of the block is screwed or otherwise secured an annular cap
or rose g provided with a central opening g¹ into which is inserted the end of a ร
speaking tube h provided with a suitable mouth-piece . The tube h may be
cither rigid or flexible.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is
First. The improved telephone transmitter hereinbefore described.
Second. A telephone transmitter having two or more contact-pieces in connection
with the external circuit forming a seat and supporting a free piece such as is
herein before described and termed a valve which forms the electrical connection
between the contact-pieces over the orifice of a tube or tubular cavity through
which the air-waves are suitably conducted so as to impinge directly upon the
valve as hereinbefore described.
Third. In a telephone transmitter, the use of a valve-seat formed of three pins or
like projections in combination with a valve such as is herein before described, in
the manner, and for the purposes, hereinbefore set forth.
Fourth. In a telephone transmitter, the use of a spherical valve such as heroin-
before described in combination with a valve-seat such as is hereinbefore described,
in the manner, and for the purposes, hereinbefore set forth.
Fifth. The arragement of our valve telephone herein before described with
reference to Figures 12 and 13 of the drawings hereto annexed.
Sixth. In a telephone transmitter, the use of a hollow spherical valve, stiffened
or stayed as hereinbefore described, in the manner, and for the purposes, hereinbefore
set forth.
3
100%
HASELTINE, LAKE & Co.,
For the Applicants.