Improvements in Telephonic Switching and Signalling Apparatus.
Year: 1890

page_text: Date of Application, 3rd Oct., 1890
Complete Specification Left, 3rd July, 1891-Accepted, 8th Aug., 1891
PROVISIONAL SPECIFICATION.
Improvements in Telephonic Switching and Signalling Apparatus.
I, HARRY THOMAS OGILVIE FRASER of 109 Farringdon Road in the City of
London Mechanical Engineer, do hereby declare the nature of this invention to be
as follows:-
This invention relates to telephonic signalling and switching apparatus of the
class of those which are described in the Specification of Letters Patent No. 2251
dated 14 February 1888 and No. 5867 dated 5 April 1889 granted to Alfred
Graham and the object of my invention is to simplify such apparatus and render it
more efficient.
According to my invention the piece which makes contact with the several
springs in connection with the different lines is carried by a disc having in its face
or side or in its edge a number of holes or recesses at intervals apart corresponding
to the position of the contact springs and the numbered indicator outside the
switch board. When the said disc is rotated a spring pin is caused to engage with
the said recesses and when the movement of rotation is discontinued the disc will
be retained in the position to which it has been brought by the pin engaging in
that one of the recesses in the disc which is opposite to the said pin--or the disc
may be retained in its adjusted position by frictional contact as hereinafter
described.
According to one arrangement I provide in the face of the disc to which the
movable contact arm is attached a number of holes or recesses corresponding to
the number of line wires in connection with the apparatus, and on the switch board
I centre a short lever having at one end a stud or projection to engage with the
said holes or recesses. This lever carries a blade spring by which the lever is
connected to the centre of the disc in such a manner as to admit of the spring
moving freely within given limits. The opposite end of this lever carries a small
cam which in its normal position is caused by a spring to project above the lever.
Crossing this lever at or near the end which carries the cam is the lever or switch
hook on which the telephone is suspended when not in use. When the telephone is
on the hook the weight thereof maintains the lever below the cam on the short
lever but when the telephone is removed from the hook the lever is raised by a
spring above the cam which is capable of yielding to allow the lever to pass to this
position without operating the short lever. After the switch lever has passed the
cam the said cam is raised by its spring into its normal position. When the
telephone is placed on the hook the switch lever descends and presses upon the cam,
which cam is prevented from turning on its centre when the lever is moving
downwards and consequently the lever carrying the cam is caused to rock on its
fulcrum and thereby disengage the pin from the hole or recess in the disc, where-
upon if the disc had been turned from its normal position it will be returned
thereto by a spring which may be the same as that which operates the switch
lever.
By this arrangement whether the switch hook lever be up or down, the disc
and contact arm may be turned in either direction and will remain at any desired
point to which they are moved, but if the switch hook lever be up the placing
of the telephone on its hook will cause the said lever to descend and by coming
into contact with the cam cause the pin on the short lever to disengage the disc for
sufficient time to allow the spring attached thereto to return the said disc and the
contact arm to their normal position at zero. The switch hook lever is provided
with a block of ebonite or other insulating material which block when the lever is
lowered presses upon a pair of spring contacts bringing them into contact with a

page_text: metal bar and when the lever is raised the block releases this pair of contacts and
presses another pair of spring contacts into contact with another contact piece or
bar. The two bars may be connected together or they may be one piece of metal
if desired. In combination with the above described mechanical arrangements I
provide an electric bell of novel construction. The armature of this bell is held in
position by a spring or springs and from it extends an arm carrying the striker
which is preferably arranged directly opposite the edge or periphery of the dome
or gong of the bell. Attached to the arm which carries the striker is a cock or
Lshaped projection opposite which is an insulated stud having two adjustable
contacts. Attached to but insulated from the armature is a spring contact which
extends to within the cock or L piece attached to the arm of the striker. The
armature and the spring contact if left free would make contact by the spring with
the cock or piece on the arm and thereby short circuit the electro magnets of
the bell. In order to regulate this and secure the proper action of the bell the
adjustable contacts in connection with the insulated stud are so adjusted that one
of them impinges on the insulated contact spring attached to the armature and the
other on the cock or picce so as to maintain the armature at the proper distance
from the poles of the electro magnets. The line connection is made with the
insulated spring attached to the armature and the insulated stud which carries the
adjustable contacts is connected to one terminal of the electro magnets the other
terminal being connected to the armature or base. When the armature is in its
normal position the current passes through the insulated spring contact and stud to
and through the electro magnets to the base, the armature being thus attracted and
the bell is sounded, but in sounding the bell this circuit is broken by reason of the
armature bringing the cock or piece into contact with the insulated spring and
thereby short circuiting the line circuit through the armature to the base. The
line circuit thus is never completely broken, the advantage of which is, that a
number of bells in series can be sounded with a single current without any trouble.
The line wires in connection with the instrument are passed through the back
board of the instrument and are connected to flat contact springs with which the
contact arm attached to the disc hereinbefore described may be brought into
electrical contact, so that each individual line may be brought in circuit with the
system; for instance when a call is transmitted the current enters the receiving
instrument by the wire connected with spring contact at zero the current_passing
first through the bell thence to the push lever and through the contact stud to the
cross bar and bottom pair of spring contacts before referred to, to earth thereby
causing the bell to ring. To acknowledge or answer the call the push button is
pressed so as to force the push lever on to a battery contact, the other pole of the
battery being in connection with earth. A current is thus sent through the bell of
the home instrument and through the disc direct to line thus not only ringing the
distant bell but also the bell of the home instrument, but to prevent the home bell
ringing with full power I provide a resistance one terminal of which is connected
to the disc and the other terminal to an insulated contact spring projecting over
the push lever so as to shunt the current from the home bell and cause it to ring
to any desired extent. A call having been received and answered and the telephone
removed from the hook the received current will enter the home instrument and
pass from the disc through the bell to the push lever, thence through the
contact stud thereof to and through the telephone to one terminal of the secondary
wire of an induction coil and from the opposite terminal thereof to the contact bar
and one of the pair of upper springs (hereinbefore referred to) to earth. When
responding, the circuit is from one pole of the speaking battery (which may be
a split in the ringing battery if desired) which is connected to one terminal of
the primary of the induction coil, thence through the said primary coil to one
terminal of the transmitter the opposite terminal of the transmitter being con-
nected to the second spring of the pair of upper springs herein before referred
to, which short circuits through the contact bar to the first or zero spring-contact
and thence to earth or to the other pole of the speaking battery. The advantage

page_text: of this particular arrangement is that when a call is made the bell of the distant
instrument will ring strong and the home bell can always be sounded while
ringing the distant bell.
According to another arrangement instead of the disc and switch arm herein-
before described a metal bar of any desired length may be employed secured at
both ends by metal studs to the apparatus. On this bar is a metal traveller or
adjustable piece which may be moved to any position along the bar and retained
by a spring.
This traveller or sliding piece carries a contact arm which performs the same
office as that attached to the disc hereinbefore described. To each end of the bar
is fixed an insulated stud each carrying a metal contact piece. Beneath and
parallel with the bar is the switch bar lever which can be freely moved up and
down between guides.
When the switch bar is in its raised position it is in contact with the metal
pieces on the insulated studs and is held in contact therewith by springs.
This switch bar lever is provided with a hook to receive the telephone when not
in use.
Beneath this bar are provided two adjustable contacts which serve to
regulate the movement of the switch bar and also to form part of the general
arrangement of the electrical connections. On the top surface of this switch bar a
series of notches are made arranged at regular intervals and corresponding in
number to the number of lines in connection with the instrument the object of
which notches is to momentarily arrest the movement of the traveller by engaging
with the insulated pin thereon when the switch lever is in its raised position.
When the telephone is placed on the hook of the switch lever the said lever is
drawn down thereby disengaging it from the pin on the traveller and permitting of
the said traveller being drawn back by its spring to zero position. The contacts ou
the insulated studs take the place of the upper pair of contact springs and the two
adjustable contacts take the place of the lower pair of springs, the switch lever and
the cross bars hereinbefore described with reference to the first arrangement.
According to another arrangement instead of making holes in the disc as in the
first described arrangement, the periphery of the disc and a portion of the switch
lever which comes into contact therewith may have their surfaces ground together
or one or both may be provided with a facing of leather or other like material to
produce friction sufficient to prevent them from moving when in contact. The
switch hook lever is preferably shaped to fit the periphery of the disc.
By this
arrangement when the telephone is off the hook and the disc is turned to the
required position it will remain there by reason of the friction between it and the
lever.
When the telephone is placed on the hook the weight thereof causes the lever to
descend out of contact with the dise which will then be drawn back by a spring to
its normal position bringing with it the contact arm to zero.
According to another arrangement I form on one side of the disc a series of
grooves or recesses and in connection with the switch hook lever is an insulated pin
which when the telephone is off the hook is acted on by a spring so as to cause it
to engage one of the grooves or recesses in the disc. The strength of the spring is
such as to admit of the disc being rotated to any desired extent but so as to retain
it in its adjusted position until the telephone is placed on the hook whereupon the
disc will be returned by a spring to its normal position.
According to another arrangement in which the disc may be rotated in either
direction the said disc is provided all round and near the periphery with holes or
recesses at regular intervals the number of holes corresponding to the number of
line contacts.
In combination with the disc is a flat spring having at its free end a pin which
engages with the holes or recesses in the disc with a suitable pressure to admit of
the disc being turned whether or not the telephone be on the hook of the switch
lever.
With this arrangement it is not necessary to return the contact arm back to zero

page_text: when a line has been used as at the zero point there is provided a contact which is
permanently connected through the bell to earth and when the contact arm of the
disc is at zero it is situated beneath the zero line spring and on top of the
connected contact piece, but when the arm is not at zero the zero line spring
makes contact with the earth contact so that in whatever position the arm may
be the circuit through the bell is complete. To reply to a call it is necessary to
move the pointer and disc by hand back to zero.
Dated this 3rd day of October 1890.
J. H. JOHNSON & Co.,
Agents.
COMPLETE SPECIFICATION.
Improvements in Telephonic Switching and Signalling Apparatus.
I HARRY THOMAS OGILVIE FRASER of 109 Farringdon Road in the City of
London Mechanical Engineer do hereby declare the nature of this invention and
in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
This invention relates to telephonic signalling and switching apparatus of the
class of those which are described in the Specification of Letters Patent No. 2251
dated 14th February 1888 and No. 5867 dated 5th April 1889 granted to Alfred
Graham, and the object of my invention is to simplify such apparatus and render
it more efficient.
According to my invention the piece or arm, which makes contact with the
several springs in connection with the different lines, is carried by a disc or its
equivalent having in its face or side or in its edge a number of holes or recesses
at intervals apart corresponding to the position of the contact springs and the
numbered indicator outside the switch board. When the said disc or its equivalent
is rotated or moved a pin is caused to engage with the said recesses and when the
movement or rotation is discontinued the disc or the like will be retained in the
position to which it has been brought by the pin engaging in that one of the recesses
which is opposite to the said pin; or the disc or the like may be retained in its
adjusted position by frictional contact as hereinafter described.
I will describe my invention with reference to the accompanying drawings
Figures 1, 2 and 3 of which represent respectively in front elevation, back
elevation, and vertical section, a switching and signalling apparatus constructed
according to my invention.
Figures 4 and 5 are respectively a front elevation and a back view of a modifi-
cation in which a straight bar is substituted for the disc employed in Figures 1,
and 3.
Figure 6 illustrates a frictional device for retaining the movable contact arm in
its adjusted position.
Figure 7 shows a spring device carried by the switch lever for retaining the
contact arm in position and
Figure 8 illustrates a further modification of the apparatus in which are provided
means for enabling the disc to be rotated in either direction and retained in its
adjusted position whether or not the telephone be on the switch hook.
Figures 9 and 10 are sections at right angles to each other of the signalling or
call bell and
Figure 11 is a diagram shewing an arrangement of two bells in the circuit from
which it will be understood that any desired number of bells may be combined in
a circuit and operated by a single current.
Referring to Figures 1, 2 and 3 A is the disc to which the movable contact
arm A2 (such as is described in the Specifications herein before referred to) is
attached and having therein a number of holes or recesses a corresponding to the
number of line wires and contact springs 6 in connection with the apparatus. On

page_text: the back of the switch board C there is centred at a², a short lever D having at
one end a stud or projection c to engage with the holes or recesses a in the disc.
This lever carries a blade spring d having a slot in its end through which passes
a pin c2 by which the lever is thus connected to the centre of the disc A in such
a manner as to admit of the spring moving freely within given limits. This lever
carries at or near its opposite end a small cam or lever e which in its normal
position is caused by a spring to project above the face of the lever. Centred
at d² to the switch board C and crossing the lever D at or near the end which
carries the cam or levere is the switch lever E with the hook F on which the
telephone G is suspended when not in use as shewn in Fig. 1. When the telephone
is on the hook F the weight thereof maintains the lever E in position below the
cam or levere but when the telephone is removed from the hook the lever E is
by a spring g raised above the cam e which yields to the pressure of the said
lever and allows it to pass without operating the short lever D. After the switch
lever has passed the came the said cam is returned to its normal position by the
spring. When the telephone is placed on the hook F the switch lever E
descends and presses upon the came which cam is not capable of turning on its
centre when pressed in this direction and consequently the lever D carrying the
cam is caused to rock on its fulcrum a² and thereby disengage the pin c from the
hole or recess in the disc A whereupon if the disc had been turned from its
normal position it will be returned thereto by the spring 9 which operates the
switch lever E.
into
Whether the switch hook lever E be up or down the disc A and contact arm A³
may be turned in either direction and will remain at any point to which they are
moved, but if the switch hook lever be up the placing of the telephone on its
hook F will cause the said lever to descend and by coming into contact with the
cam cause the pin on the short lever to disengage the disc for sufficient time to
allow the spring to return the contact arm A to its normal position at zero.
The switch hook lever E carries a block of ebonite or other insulating material
which when the lever is lowered presses upon a pair of spring contacts i bringing
them into contact with a metal bar k and when the lever is raised the block
releases this pair of contacts and presses another pair of spring contacts
contact with another metal bar m. The two bars k and m may be connected
together or they may be one piece of metal if desired. In combination with the
above described mechanical arrangement I may employ an ordinary call bell but
I prefer to employ an electric bell of novel construction as illustrated in Figures 9
and 10 and hereinafter fully described. The line wires M in connection with the
instrument are passed through the back board of the instrument and are connected
to the flat contact springs b with which the contact arm A2 attached to the disc A
may be brought into electrical contact so that each individual line may be brought
in circuit with the system, for instance when a call is transmitted from a distant
station the current enters the receiving instrument by the line wire M³ connected
with zero spring contact and passes by the arm A2 and disc A. and through the
wire v to the bell H thence by the wire Q to the lever N of a push button O
and through the contact stud w and wires to contact spring the cross bar k
and spring contact thence by wire y to earth thereby causing the bell to ring.
To acknowledge or answer the call the push button Ŏ is pressed so as to force
the push lever N on to a contact P connected to one pole of a battery by the
line the other pole of the battery being in connection with earth. A current is
thus sent through the contact B push lever N and wire Q to the bell of the home
instrument and thence through the wire to the disc A and arm A² direct to
line thus not only ringing the distant bell but also the bell of the home
instrument.
A call having been received and answered and the telephone removed from the
hook F the received current will enter the home instrument as before by the
line M and pass from the disc through the bell to the push lever N, thence
through the contact stud w and wire to and through the telephone cord T and

page_text: wire U to one terminal of the secondary wire of an induction coil V and from
the opposite terminal thereof by the wire W to the contact bars & and m and the
spring of the upper pair of springs to earth by the wire Y. When responding
the circuit is from one pole of the speaking battery (which may be a split in the
ringing battery if desired) by the wire X which is connected to one terminal of
the primary of the induction coil V thence through the said primary coil to the
contact bar and contact spring and wire to one terminal of the transmitter Y
the opposite terminal of the transmitter being connected by the wire 13 to earth
or to the other pole of the speaking battery. To call up a distant station the
disc A is turned by means of the knob or handle Z, so as to cause the arm A² to
make contact with the spring b which corresponds to the number on the front of
the instrument indicating the station with which it is desired to communicate, then
by depressing the push button ( a current will be sent through the bell of the
instrument at that station. The reply current from the distant station enters the
home instrument by the line wire M in connection with the said distant station
and passes through the disc A as herein before described.
Instead of the disc and switch arm for making the contacts by a circular
motion as herein before described the arrangement illustrated in Figures 4 and 5
may be employed and consists of a metal bar (1) of any desired length secured at
both ends to the back of the switch board. On this bar is a metal traveller or
adjustable piece A which may be moved to any position along the bar 1.
This traveller or sliding piece carries a contact arm A² which performs the
same office as that attached to the disc hereinbefore described. The traveller A
is connected to the free end of a coiled spring which tends to draw the traveller
g
to the end of the bar 1 at which the zero spring contact is situated. To each
end of the bar 1 is fixed an insulated stud 2 2× eacli carrying a metal contact
piece 3 3×. Beneath and parallel with the bar is the switch bar or lever E which
can be freely moved up and down in guides 4.
When the switch bar is in its raised position that is when the telephone is
removed from the hook F it is in contact with the pieces 3. 3× on the insulated
studs 2. 2* and is held in contact therewith by springs 5.
Beneath the bar E are provided two adjustable contacts 6 which serve to
regulate the movement of the switch bar and also to form part of the general
arrangement of the electrical connections. On the top surface of this switch bar E
a series of notches a are made arranged at regular intervals and corresponding in
number to the number of lines M in connection with the instrument the object of
these notches being to momentarily arrest the movement of the traveller A by
engaging with an insulated pin 7 thercon when the switch lever is in its raised
position. When the telephone is placed on the hook F of the switch lever or
bar E the said lever is drawn down, thereby disengaging it from the pin 7 on the
traveller and permitting of the said traveller being drawn back by the spring g
to zero position. The contact pieces 3. 3× on the insulated studs 2. 2x take the
place of the upper pair of contact springs herein before described with reference
to Figures 1, 2 and 3 and the two adjustable contacts 6 take the place of the lower
pair of springs i i¹.
According to another arrangement as illustrated by Figure 6 instead of making
holes in the disc A as in the first described arrangement, the periphery of the said
disc and a portion of the switch lever E which comes into contact therewith have
their surfaces ground together or one or both may be provided with a facing of
leather or other like material to produce friction sufficient to prevent the disc
from turning when the telephone is off the hook.
The switch hook lever is preferably shaped as shewn at 8 to fit the periphery of
the disc A. By this arrangement, when the telephone is off the hook and the
disc A is turned to the required position it will remain there by reason of the
friction between it and the lever E.
1, 1, and i, 2 are respectively the upper and lower pair of contact springs
corresponding to those described with reference to Figures 1, 2, and 3, and

page_text: the connections and remaining parts may be similar to those hereinbefore
described.
When the telephone is placed on the hook the weight thereof causes the lever E
to descend out of contact with the disc which will then be drawn back by the
spring g. to its normal position bringing with it the contact arm to zero.
According to another arrangement as illustrated in vertical section in Figure 7,
I form on one side of the disc A. a series of grooves or recesses a and in connection
with the switch lever E is an insulated pine which when the telephone is off the
hook is caused by a spring e' to engage one of the grooves or recesses a in the disc
the strength of the spring being sufficient to retain the disc in its adjusted position
until the telephone is placed on the hook but not strong enough to prevent the disc
being rotated to any desired extent by the handle Z.
When the telephone is placed on the hook of the switch lever E the said lever
will descend and disengage the pin e from the disc which will then be returned by
a spring similar to the spring g, herein before described, to its normal position.
According to another arrangement illustrated by Figure 8, the disc A. may be
rotated a complete revolution in either direction and is provided all round and near
the periphery with holes or recesses a at regular intervals, the number of holes
corresponding to the number of line contact springs b.
In combination with the disc is a spring & having at its free end a pin c which
engages with the holes or recesses a with a suitable pressure to admit of the
disc being turned whether or not the telephone be on the hook of the switch
lever.
With this arrangement it is not necessary to return the contact arm A² back to
zero when a line has been used, as there is provided at the zero point a contact
piece 9 which is permanently connected through the bell to earth.
When the contact arm A² of the disc is at zero, it separates the zero line
spring from the earth connected contact piece 9, but when the arm is not at zero
the zero line spring makes contact with the earth contact piece 9 so that in
whatever position the arm may be the circuit through the bell is complete. To
reply to a call it is necessary to move the pointer and disc back to zero.
the other parts of the instrument and the connections may be like those herein-
before described.
All
The bell which I prefer to employ in combination with my improved switching
device is provided with a metal base o (see Figures 9 and 10) by which it may be
fixed to any suitable support and to this base is fixed the electro magnet L. carrying
the gong H of the bell. The armature n of the electro magnet is attached to the
base o by a spring arm p. and connected to this arm or to the armature direct is the
hammer or striker which is preferably arranged directly opposite the edge or
periphery of the gong
2"
H.
Formed in one with or attached to the spring arm or to the armature n or
arranged so as to be operated thereby, is a metal arm or plate I, provided at its
outer end with a recess or hook I' in which enters the outer free end of a springy
metal arm or contact plate u secured to but insulated from the base o and the
arms pand. I. Attached to, but insulated from the base o and projecting over the
hooked or recessed end of the arm I. is a plate K. carrying two adjustable studs s.
and t. with which the arms I. and u when in their normal position are respectively
in contact. The studs is made of or provided at its contact end with insulating
material to prevent short circuiting of the current which would take place if the
plates or arms I and u were left free to make contact with the plate K. and to pre-
vent this the studs s and are so adjusted that in the normal condition of the bell
the arm u is depressed by the stud t, out of contact with the arm 1. and the insulated
studs bears on the arm I. so as to keep it out of contact with the plate K. and the
armature at the required distance from the poles of the electro magnet L. If
desired, the arms and I and the striker of the bell may be made in one with
the armature n but I prefer to make them in separate pieces for convenience of
manufacture.

page_text: The line connection Fig. 2 is made with the spring contact plate u and the
electro-magnet L is connected by one of its terminals with the insulated plate K
and by its other terminal with the base o of the bell.
Figure 11. is a diagram shewing in combination with Figure 9. the course of the
current through the bells at two stations indicated by the letters H. and H2. A
current sent from the station indicated by H. passes as shewn by the arrows from
the battery by the contact P to the insulated spring contact plate of the bell H
Figure 9. and thence through the stud and plate K. to the terminal of the electro
magnet and through said magnet and its terminal 15 to the base o and line M. The
electro magnet of the bell H being thus excited attracts the armature n thereby
sounding the bell and at the same time raising the arm I. into contact with the
spring contact plate u so as to break the contact thereof with the stud t. The
electro-magnet is thus cut out of the circuit and the current short circuited through
the armature n to the base o whence it passes as shewn by dotted arrows in Figure 9
by the line M to the bell H2 Figure 11. entering the said bell by its spring contact
plate and ringing the bell in the manner described with reference to Figure 9
the circuit being completed through earth. If other bells are included in the line
the current will pass from one to another in series and thereby sound the whole
of the bells with a single current without the circuit being broken. To prevent the
bell at the sending station sounding with full power there is provided a shunt
wire (see also Fig. 2) in which a resistance R is placed one terminal v² of which
is connected to the contact N. and the other terminal is connected by the wire v² to
the switch board as shewn in Figure 2, so that when the contact at N. (Figures 2
and 11) is made, a portion of the current will pass through the shunt wire v and
resistance R. and thus reduce the power of the magnet of the bell H. In addition
to the advantage by this arrangement of reducing the power of the bell of the
sending instrument the line circuit is never completely broken and a number of
bells in series can be sounded with a single current.
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
First. In telephonic switching and signalling apparatus the combination with
fixed contact pieces in connection with the different lines connected with the
apparatus, of an adjustable contact piece capable of being moved into contact with
any one of the fixed contact pieces and retained in its adjusted position whether or
not the telephone be on the switch hook and means for effecting the release of the
movable contact piece when the telephone is placed on the hook of the switch lever
substantially as hereinbefore described.
Secondly. In telephonic switching and signalling apparatus of the class herein-
before described the combination of the disc A and arm A² for making contact
with any one of the spring contacts b, the lever d having at one end a pin c for
engaging in holes or recesses a in the disc A. and having centered at its opposite
end a cam or lever e capable of turning from its normal position in one direction
only the said cam or lever e when in its normal position being caused to project
above the surface of the lever d so that when the switch lever E is being depressed
it will engage the cam or lever e and cause the lever to turn on its centre and
thereby disengage the pin c from the hole or recess in the disc A. to permit of the
disc returning to its normal position the whole being arranged substantially as
hereinbefore described and illustrated in Figures 1, 2 and 3 of the accompanying
drawings.
3. In telephonic switching and signalling apparatus an electric bell constructed
and arranged substantially as herein before described with reference to Figures 9
and 10 of the drawings whereby the line circuit in connection therewith is never
completely broken and a number of bells in series can be sounded with a single
current substantially as hereinbefore described.
4. The general construction and combination of parts constituting the improved

page_text: telephonic switching and signalling apparatus hereinbefore described and illustrated
by Figures 1, 2 and 3 of the accompanying drawings.
5. In telephonic and signalling apparatus the combination with fixed contact
pieces in connection with the different lines connected with the apparatus of a
moveable contact piece fitted to slide on a fixed bar and provided with a projection
to engage in notches in a bar connected to the hook which supports the telephone
when not in use the said bar being caused to engage the projection on the sliding
contact piece when the telephone is removed from the hook so as to retain the sliding
contact in the position to which it had been moved the said movable contact being
released and caused under the action of a spring to return to its normal position
when the telephone is placed on the hook substantially as herein before described
with reference to Figures 4 and 5 of the accompanying drawings.
6. The combination and arrangement of the parts constituting the improvements
in telephonic switching and signalling apparatus hereinbefore described and
illustrated by Figures 4 and 5 of the accompanying drawings.
7. In telephonic switching and signalling apparatus of the class hereinbefore
described providing on the periphery or a portion of the periphery of the disc
which carries the movable contact arm a frictional surface, by grinding or covering
it with leather or the like, a like frictional surface being provided on the switch
lever at the part where it comes into contact with the disc so as to retain the disc
in the position to which it had been moved when the telephone is off the switch
lever substantially as hereinbefore described with reference to Figure 6 of the
accompanying drawings.
8. In telephonic switching and signalling apparatus of the class hereinbefore
mentioned the combination with the disc A having recesses a in its face of a
yielding pin or projection c on the switch lever E engaging with the said recesses a
to retain the disc in its adjusted position when the telephone is off the switch lever
but allowing of the disc being rotated substantially as hereinbefore described with
reference to Figure 7 of the accompanying drawings.
9. In telephonic switching and signalling apparatus of the class hereinbefore
referred to the combination of the disc A carrying the contact, arm A² and having
a series of holes or recesses a arranged in a circle near the periphery the said disc
being capable of being rotated in either direction, a spring detent engaging the
holes a to retain the disc in its adjusted position a contact piece situated beneath
the spring contact piece bl of the series of fixed contact pieces b in connection with
the line wires, the whole being arranged substantially in the manner and for the
purpose hereinbefore described with reference to Figure 8 of the accompanying
drawings.
1001 1