IMPROVEMENTS IN TELEPHONIC APPARATIIS
Year: 1883

page_text: LETTERS PATENT to George Henry Bassano, Albert Edward Slater and
Frederick Thomas Hollins all of Derby in the county of Derby for an
Invention of IMPROVEMENTS IN TELEPHONIC APPARATIIS
PROVISIONAL SPECIFICATION left by the said George Henry Bassano,
Albert Edward Slater, and Frederick Thomas Hollins at the Office of the
Commissioners of Patents on the 10th March 1883.
GEORGE HENRY BASSANO, ALBERT EDWARD SLATER and FREDERICK THOMAS
HOLLINS all of Derby in the county of Derby
"IMPROVEMENTS IN TELEPHONIC
APPARATUS
"
The first part, of this invention relates to telephone transmitters and is a
modification of Professor Hughes microphone with several novel arrangements
and improvements
It has hitherto principally been the practice where carbon pencils are employed
to secure the diaphragm or sound board all round its edges or at both ends or
both sides and fix the pencils in any suitable manner in the centre of the
diaphragm.
Under this invention we propose to use a diaphragm or tongue sounding board
of any resonant material secured only at the bottom or if a diaphragm is fixed in
a horizontal position at one end, leaving the top or the other end and the sides
unsecured so as to allow of its free vibration.
We fix in a suitable manner the carbon pencils at the top or loose end so as to
obtain the greatest amplitude of vibration.
An important part of this invention is that the pencils are used separately to
form multiple microphonic primary circuits.
It is well known that the battery power employed on the microphone for
transmitting sounds cannot advantageously be increased as an increase in the
battery power decreases the variation in the resistance of the carbon.
I
We propose to take two or more carbon pencils to a block of each of which
we connect a separate battery of one two or more cells and from each of the blocks
Prins 11

page_text: at the other end of each of the carbon pencils the separate circuits are continued
to one or more induction coils as may be preferred
It will be at once apparent that the battery power can thus be easily and
advantageously increased.
To each of the pencils a spring or magnetic tension is given so as to prevent
contact being broken or multiple contact in each pencils is obtained by using
serrated or fluted pencils and the blocks in which they rest having prolongations
or arms resting on the top (or if made in another manner on the bottom or on the
top and bottom) of the pencils
The blocks are loosely attached to the diaphragm or board by screws or other
means in such a manner that constant contact is maintained by gravity.
We also propose to fix carbon contacts on this description of diaphragm or
tongue sounding board as hereinbefore described in another form and in another
manner
At the back and near the top of the diaphragm several small blocks of carbon
of suitable shape are fixed and the same number of a similar or other shape are
fixed, to the back of the instrument or upon a projection from the back.
The loose diaphragm is then so held in position that contact is always made
by the carbons by means of small blocks of india rubber or springs or other suitable
device thus preventing the shrinking of the wood or other causes allowing contact
to be broken.
We also propose to fix carbon contacts of another description to this form of
diaphragm.
In front of this said diaphragm and slightly distant therefrom we fix a strip
of wood or other material across from side to side of the case and near the top of
the board. Along this strip of wood or other material we secure one or more small
carbon bridges of any shape and opposite those on the tongue sounding board or
diaphragm we fix other bridges and connect the two across by means of one or
more carbon rings.
It will be obvious that in this kind of diaphragm the pressure of the carbon
contacts on each other will be very nicely adjusted and capable of great variation
as the board vibrates more or less in consonance with the strength of the sound
waves acting thereon.
We also make use of a switching arrangement whereby the intermediary wires
used in carrying out one part of this invention may be cut out so that when the
microphone is switched out of circuit the whole of the battery power may be
available for the call bell.
The second part of this invention relates to telephone receivers.
The principle of telephone receivers previously known (of practical utility) has
been the reproduction of speech by tympanic vibration.
We propose to make telephone receivers upon a different principle.
In a cylinder or recess or without a cylinder or recess in a case of suitable
material size and shape we place a moveable plug or piston, disc or plate of
ebonite or other suitable material fitting well but free to move in the cylinder or
recess or otherwise and rigidly fixed to a spring or other suitable device which
holds it in a firm and central position.
At the other side of this spring or holder an armature of any suitable shape is
attached which vibrating to the pulsations of the undulatory current sent round
an electro magnet sets in rapid motion the piston or plug disc or plate.
Or the armature itself may be made the spring holder and armature combined.
A telephone receiver constructed in this manner and on this principle gives out
clear and distinct articulation of the words spoken to the transmitter.
This principle is capable of application in several ways some of which will be
hereinafter described and set forth, but three of which we here mention.
The said piston or plug disc or plate instead of being held rigidly and centrally
to a spring or holder as herein before described may be hung upon a hinge or other
device inside a suitable cylinder or recess and held in position by suitable springs

page_text: and being attached to an armature thus set in motion as before mentioned or it
may be placed upon an axis and held in position by springs and attached to one
or two armatures as preferred or the said piston or plug disc or plate may be
made in two pieces both fixed on a central axis and attached to armatures in a
suitable manner.
We propose to make this telephone either singly or double or with single or
double tubes
The said piston or plug disc or plate may also be fixed to the spring or holder
as herein before described and being attached to a rod of suitable metal receive its
necessary backward and forward motion by the elongation and contraction of the
metal rod due to the varying magnetism sent round the rod placed in a suitable
tube or otherwise.
The said piston or plug disc or plate may also be made of metal capable of
inductive action and being held in a central position by a suitable spring or
holder" be made to move bodily by the direct action of the electro magnet on the
plug or piston disc or plate itself.
46
We also propose to make a telephone receiver by fixing a diaphragm whether
solid or perforated of ebonite brass or other non inductive material on the edges
of the case and attaching the centre of the same to a rigid armature of an electro
magnet either in centres or springs using either one or both poles of the magnet
By fixing a plate of suitable material over the pole or poles of the electro magnets
of present known receivers and letting the pole piece or pieces through thus
making a small recess or cylinder between the magnets and the vibrating plate
similar to the one at present formed in front of the said plate better results are
obtained

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said George Henry Bassano, Albert Edward Slater, and Frederick
Thomas Hollins in the Great Seal Patent Office on the 8th September 1883.
GEORGE HENRY BASSANO, ALBERT EDWARD SLATER and FREDERICK THOMAS
HOLLINS all of Derby in the County of Derby
"IMPROVEMENTS IN TELEPHONIC
APPARATUS
"
The first part of this invention relates to telephone transmitters and is a
modification of Professor Hughes' microphone with several novel arrangements
and improvements
It has hitherto principally been the practice where carbon pencils are employed
to secure the diaphragm or sound board all round its edges or both sides and fix
the pencils in any suitable manner in the centre of the diaphragm.
Under this invention we propose to use a diaphragm or tongue sounding board
of any resonant material secured only at the bottom or if a diaphragm is fixed in
a horizontal position at one end leaving the top or the other end and the sides
unsecured so as to allow of its free vibration and in combination with an arrange-
ment of carbon pencils hereinafter described.
We fix in a suitable manner the carbon pencils at the top or loose end so as to
obtain the greatest amplitude of vibration. An important part of this invention
is that the pencils are used separately to form multiple microphonic primary
circuits. It is well known that the battery power employed on the microphone
for transmitting sounds cannot advantageously be increased as an increase in the
battery power decreases the variation in the resistance of the carbon. We propose
to take two or more carbon pencils to a block of each of which we connect a
separate battery of one two or more cells and from each of the blocks at the other
end of each of the carbon pencils the separate circuits are continued to one or
more induction coils as may be preferred.
It will be at once apparent that the battery power can thus be easily and
advantageously increased. To each of the pencils a spring or magnetic tension is
given so as to prevent contact being broken, or multiple contact is obtained by
using serrated or fluted pencils and the blocks in which they rest having prolonga-
tions or arms resting on the top (or if made in another manner on the bottom or
on the top and bottoni) of the pencils.
The blocks are loosely attached to the diaphragm or board by screws or other
means in such a manner that constant contact is maintained by gravity.
We also make use of a switching arrangement hereinafter more particularly
referred to whereby the intermediary wires used in carrying out one part of this
invention may be cut out so that when the microphone is switched out of circuit
the whole of the battery power may be available for the call bell.
The second part of this invention relates to telephonic receivers. .
The principle of telephone receivers previously known (of practical utility) has
been the reproduction of speech by tympanic vibration. We propose to make
telephone receivers upon a different principle. In a cylinder or recess or without
a cylinder or recess in a case of suitable material size and shape we place a
movable plug or piston disc or plate of ebonite or other suitable material fitting
well but free to move in the cylinder or recess or otherwise and rigidly fixed to a
spring or other suitable device which holds it in a firm and central position.
At the other side of this spring or "holder an armature of any suitable shape
is attached which vibrating to the pulsations of the undulatory current sent round
an electro magnet sets in rapid motion the piston or plug disc or plate, or the
armature itself may be made the spring, holder and armature combined as herein-
after described and shewn. A telephone receiver constructed in this manner and
on this principle gives out clear and distinct articulation of the words spoken to
"

page_text: the transmitter. This principle is capable of application in several ways such as
are hereinafter described and set forth. The said plug or piston disc or plate
" as hereinbefore
instead of being held rigidly and centrally to a spring or "holder
described may be hung upon a hinge or other device inside a suitable cylinder or
recess and held in position by suitable springs and being attached to an armature
thus set in motion as before mentioned or it may be placed upon an axis and held
in position by springs and attached to one or two armatures as preferred and as
hereinafter described and shewn; or the said piston or plug disc or plate may be
made in two pieces both fixed on a central axis and attached to armatures in a
suitable manner.,
We propose to make this telephone either single or double or with single or
double tubes.
The said piston or plug disc or plate may also be fixed to the spring or "holder"
as herein before described and being attached to a rod of suitable metal receive its
necessary backward and forward motion by the elongation and contraction of the
metal rod due to the varying current sent-round the rod placed in a suitable tube
or otherwise as hereinafter described and shewn.
The said piston or plug disc or plate may also be made of metal capable of
inductive action and being held in a central position by a suitable spring or
"holder" be made to move bodily by the direct action of the electro magnet on
the plug or piston disc or plate itself.
And in order that our invention may be more fully understood we now proceed
to describe the accompanying drawings in reference thereto.
Figures 1. 2. 3 and 3° relate to the transmitter. Figure 1 is a general view of
the connections of the complete apparatus shewing the microphone circuits and
the switching arrangement for coupling up for intensity the separate batteries into
one complete battery for the "call bell" call attention" sigual. Figures 2
and 3 shew the novel form of carbon pencil or contact and Figure 3* the tongue
sounding board on which to mount the pencils.
"
ог
In Figure 1 X Y Z shew three separate batteries in the well known manner-
the thick lines representing the zinc or negative poles and thin lines the positive
poles. P. P. P. are three carbon pencils (which in practice are mounted preferably
at the top of a tongue sounding board as is shewn in Figure 3*) to one end of
each of the blocks in which the pencils rest wires are led from the terminals C. C¹. C'
brauch wires also connecting those from terminals C¹. C². to contact points 0. 01.
the object of which will be hereinafter explained. From the carbon block at the
opposite side of each pencil connection is made to one wire (if one induction coil
only is used) and forms the primary of the induction coil I and thence to the
contact M which when the microphone is in circuit is in contact with the switching
arm S W.
If, however, separate induction coils are used for each pencil separate wires
must be led from each pencil to its own induction coil forming the primary of the
same and thence be led to the contact points A A' which must then of course be
disconnected from the axle of the switching arm S. W. The secondary wires of
the induction coils (when more than one is used) may be joined up in any suitable
manner one way being to join all the inner ends together and all the outer ends
together which is for " quantity" and which has the effect also of reducing the
resistance of the secondary wire to considerably less than if only one induction coil
was used or the inner end of one may be joined to the outer end of the other and
so on for "intensity."
The zinc poles of the batteries Y Z are connected to the terminals Z¹ Z³ and
thence as clearly shewn to the fixed portions of the lever springs S. St. the zinc
pole of the battery X remaining always in contact with the axle of the switching
arm S. W. through the terminals Z E which is also the "earth" terminal. When
only one induction coil is used contact points A A¹ are also connected to the axle
of the switching arm S W as shewn in Figure 1. S S¹. are lever springs which
may be of any suitable shape or arrangement and which when the switching arm

page_text: .
"
or rest SW is pressed or pulled down are moved out of contact with contact
points A. A. into contact with the points O. 01. at the same time contact between
the switching arm S W and M is broken. The microphone is then out of circuit and
the bell B is switched in by the arm S W making contact with b and the zine poles
of the batteries Z and Y are coupled up with the copper or other poles of the
batteries Y X thus forming one complete battery for " intensity and which is
available for the "call" bell or "call attention" signal. We sometimes have
separate primary wires from each pencil and separately coiled on one induction
coil having only one secondary wire. The "primarys" in this case would be
attached to contact points A A¹ and M and the secondary wire.as shewn―lever
spring S³ is also actuated by the switching arm S. W. and when in contact with
the point F completes the secondary circuit. When however the arm S W is
pressed or pulled down the secondary circuit is broken so that any current from line
must pass through the bell B. We sometimes however prefer when two arins or
rests are required to hold the tubes or telephone receivers to have this contact
made and broken by means of the second arm or rest in the usual manner and
which will be well understood. The remaining parts are L the line wire terminal,
K the ringing key and T the telephone receiver.
Figures 2 and 3 shew the novel form of carbon pencil or contact advantageously
used, a being a serrated or fluted pencil and D being the two descriptions of
carbon blocks in which they rest having prolongations or arms in one case resting
on the top and in the other underneath the pencils in both cases constant contact
being maintained by gravity the blocks being loosely held on suitable studs or
screws at the points indicated or in other suitable manner.
Figure 3 A shows the tongue sounding board advantageously made of pine on
which the pencils P P P are mounted (the ordinary description of pencil being
for the sake of simplicity shewn) with small spiral springs W. W. W². attached
thereto to prevent contact being broken by any "jump" of the pencil as will be
understood. We sometimes prefer to attach the battery wires to these springs 80
that if contact should be broken at one end it would not be at the other. In this
case we attach both carbon blocks together by means of the wire forming the
primary of the induction coils. We always prefer to mount the pencils at the top
of the tongue sounding board which being the greatest point of amplitude of
vibration gives the best results.
Sheets 2 and 3 shew our receiver in various modifications.
Referring to. Figures 4 to 7 we show our receiver as fitted with tubes for
conveying sounds to the ears.
In these figures Figure 4 shews the apparatus as more of the form of a
" piston."
Figure 5 shews it hung from the spring so as to have more of a vibratory than a
strictly rectilinear movement.
In Figure 6 the axes of the armature and magnet coincide.
In Figure 7 the diaphragm is supported by the spring.
In all these figures a is the case, 6 the piston or plug disc or plate, c the spring,
d the holder, e the armature. I coils on magnet M.
On Sheet 3 Figure 8 is a longitudinal section of a more portable form of
instrument shewing our apparatus fitted in a case of well known form. In this
Figure a is the case, 6 the disc or plate, c the spring and d the armature.
Figures 9 and 10 shew details of the front and side views of the armature.
The armature d¹ moves on adjustable centres e. e'. carried by a plate of screwed
or fastened to the inside of the case.
The armature is secured at g to the holder or piston rod d and so the attraction
of the magnet pulls on the armature e which therefore vibrates on the centres e e¹.
Instead of on centres as in Figures 9 and 10 the armature could vibrate on a
pin e as shewn in Figure 8 or the armature by being made of soft iron could be
made the spring holder and armature combined as shewn in Figure 11.
Figure 12 shews a circular form of spring sometimes. used.

page_text: There are of course many forms of springs or holders which would answer the
purpose. Any description of spring of suitable shape and strength to bold the
piston or plug disc or plate in position and to bring it back sharply into its
normal position when drawn out of it by the action of the magnet will answer the
purpose.
It is in the exact suitability of the spring or holder that the loudness and
clearness of articulation mainly depends. It is obvious also that the spring or
holder may be formed out of the same piece of material as the disc or plate b
provided always that it is thinned to the proper strength and if this is wholly or
in part made of material capable of inductive action the magnet M may act
directly thereon as described in our provisional Specification. It is also obvious
that a cylinder or recess to all intents and purposes answering the requirements of
this invention may be formed in many ways. In front of the piston or plug disc
or plate b a face or plate of wood or other material to carry the tube or tubes
may be rigidly fixed and to the edges or circumferences of both any suitable.
flexible air tight material such as thin leather may be attached thus forming a
cylinder or recess or air space the exact equivalent of the cylinder herein
described. Fair results however may be obtained without a cylinder and with
the disc or plate piston or plug left open and exposed and merely vibrating in front of
a flat surface or support carrying the tube or tubes or other contrivance for conveying
the sounds to the ear. As it is desirable that the movement of the piston or plug or disc
or plate should be air tight (although it is not essential but improves the efficiency of
the instrument) we sometimes prefer to attach round the edge or circumference of the
plate b and the cylinder a a flexible cover of thin leather, parchment or other
suitable air tight material. As previously mentioned however this is not necessary
to the working of the instrument but improves it, the object being to force the
air before the plate or disc. It is clear that on any movement of the armature e
the disc or plate 6 makes a central bodily piston like movement either backward
or forward as the magnet M may pull or release the armature e consequently when
in action the vibration of the air in the cylinder is equally as great at one point
as another over the whole surface of the piston or plug disc or plate as contra-
distinguished from where a tympanum is used in the latter case the greatest
amplitude of vibration being in the centre falling to nothing at the circumference.
When the piston or plug, disc or plate therefore is air tight the displacement of air
in the cylinder is greater and the rarefactions and condensations more marked
when vibrated than is the case where a tympan is employed.
Figure 13 shows a cross sectional view of a receiver in which the disc or plate b
in the cylinder d is made to vibrate by the elongation and contraction of a thin
rod D of iron steel or other suitable material due to the magnetisation of the same
by a helix or coil of insulated wire E coiled round a tube H of ebonite glass or
any material suitable for the purpose. d is the cylinder as before, b the piston or
plug, disc or plate c a small narrow straight spring to hold the disc or plate in
position and also to keep the rod D in a central position in the tube H. E is the
coil or helix of covered or insulated wire W a nut for the purpose of regulating
the rod D whilst t. t. are the terminals of the instrument. When a current of
electricity is sent round the coil or helix of wire E the rod D contracts or expands
accordingly as it is charged with a positive or negative current any variation in
the current causing a corresponding variation in the contraction or expansion of
the rod D and thus vibrating the disc or plate b. As shewn it has a straight
bodily piston like movement but this principle is equally applicable to some or all
of the forms of instruments described in this Specification.
With reference to the switching arrangement we do not bind ourselves to the
particular form of switching arrangement shown for it will be obvious that the
same thing may be done in many ways and may be made to couple up any suitable
number of batteries and not the number shewn in the drawing only.
And now having fully described the nature of our said invention we do hereby
declare that what we consider novel and therefore what we claim is: -

page_text: Firstly. In a telephone transmitter the fluted or serrated pencils in combination
with blocks having prolongations or arms substantially as described and illustrated
in Figures 2 and 3 and 3 A.
Secondly. In a telephone transmitter in which pencil contacts are used the
arrangement of multiple microphonic circuits as described in combination with a
switching arrangement for coupling up two or more batteries into one complete
battery for "intensity" for the "call bell" or "call attention signal" substantially
as described and shewn in Figure 1.
Thirdly-In a telephonic receiver the use of a piston or plug disc or plate as
described not secured round its edges reciprocating or moving bodily by the action
of an electro or permanent magnet (or by the varying expansion or contraction of
a metal rod placed in a helix through which a current is passed) such piston or
plug, disc or plate being held in a central or approximately central position (or
from its end or sides by a point of suspension) by a spring holder or its equivalent
in combination with a cylinder or recess as and for the purposes described.
In witness whereof we the said George Henry Bassano, Albert Edward Slater
and Frederick Thomas Hollins have hereunto set our hands and seals this fifth
day of September, in the year of our Lord One thousand eight hundred and
night throa
GEORGE HENRY BASSANO
ALBERT EDWARD SLATER
(LS.)
(L.S.)
FREDERICK THOMAS HOLLINS (L.S.)