IMPROVEMENTS IN AND RELATING TO TELEPHONIC APPARATUS com
Year: 1883

page_text: LETTERS PATENT to William Robert Lake, of the firm of Haseltine Lake
”
& Co., Patent Agents Southampton Buildings, London for an Invention of
"IMPROVEMENTS IN AND RELATING TO TELEPHONIC APPARATUS commu-
nicated to him from abroad by Edwin Holmes of Brooklyn and Edwin
Truman Greenfield of New York, both in the State of New York United
States of America.
COMPLETE SPECIFICATION filed by the said William Robert Lake at the
Office of the Commissioners of Patents on the 1st March 1883.
"
WILLIAM ROBERT LAKE of the firm of Haseltine, Lake, and Co, Patent Agents,
" IMPROVEMENTS IN
Southampton Buildings, London
AND RELATING ΤΟ
TELEPHONIC APPARATUS Communicated to me from abroad by Edwin Holmes,
of Brooklyn, and Edwin Truman Greenfield, of New York, both in the State of
New York, United States of America,
This invention relates to improvements in telephonic exchange systems and to
apparatus therefor.
$
The said invention partly consists in the combination in a telephonic exchange
system, of a number of subscribers' service lines with a multiple telephonic receiver
at a central office, normally in circuit with the service lines, a single telephonic
transmitter at the central office, normally out of circuit, and means whereby this
telephonic transmitter may be put in circuit with any of the service lines
It further partiý consists in the combination in a telephone exchange system of
a number of subscribers' service lines with a multiple telephonic receiver at a
central office normally in circuit with the service lines, a single telephonic
transmitter at the central office normally out of circuit, and a switch-board whereby
different service lines may be put in circuit with each other or with the telephonic
transmitter.
It further partly consists in the combination in a telephone exchange system
of a number of subscribers' service lines, and a multiple receiver located at a
central office, having a number of diaphragms and electro-magnets and a sound
passage common to all.
It further partly consists in the combination in a telephone exchange system of

page_text: a number of subscribers' service lines, and a multiple receiver located at a central
office having a number of diaphragms, and a corresponding number of electro-
magnets arranged opposite the centres of the diaphragms and severally provided
with a plurality of coils
It further partly consists in the combination in a telephone exchange system of
a number of subscribers' service lines and a multiple receiver at a central office
suspended over the portion occupied by the operator
It further partly consists in the combination in a telephone exchange system of
a number of subscribers' service lines, and a multiple receiver at a central office
suspended over the position occupied by the operator and having a head-piece for
the operator.
It further partly consists in the combination in a telephone exchange system of
a number of subscribers' service lines and a multiple receiver at a central office
suspended over the position occupied by the operator and having a sound passage
terminating in a head-piece provided with sound passages adapted to lead to the
ears of the operator.
It further partly consists in the combination in a telephone exchange system of
a number of subscribers' service lines and a multiple receiver at a central office
suspended over the position occupied by the operator and having a flexibly
connected head-piece for the operator.
In the accompanying drawings
Figure 1 is a diagram of an apparatus embodying the said invention.
Figure 2 is a front view of a switch board and a series of annunciator drops
frming part of the apparatus
Figure 3 is a vertical section of a portion of the switch board drawn to an
enlarged scale
Figure 4 is a vertical section of the switch-board at right angles to Figure 3
Figure 5 is a view of the underside of a portion of the switch-board.
Figure 6 is a side view of a multiple receiving instrument forming part of the
apparatus
Figure 7 is a vertical section drawn to an enlarged scale of the multiple receiver
Figure 8 is a horizontal section of the multiple receiver
Figure 9 is a transverse section of certain parts of the multiple receiver
Figure 10 is a side view drawn to an enlarged scale of one of the annunciator
drops; and
Figure 11 is a horizontal section of the same.
Similar letters of reference indicate corresponding parts throughout the drawings
A¹ A² to A (see Figure 1) indicate the premises of various subscribers' or
customers in communication with the same central office. Only a few subscribers'
places are indicated in the drawings, and they are supplied with telephonic
receivers and transmitters as usual and their instruments are in communication
with the ground. I have indicated this by showing wires B¹ B to B leading to
earth plates C¹ C³ to C³
•
Wires D¹ D to D³ extend from the subscribers' to the switch-board at the central
office. As shown these wires are connected to binding screws at the sides of the
switch-board. In the diagram Figure 1 the sides and top of the switch-board are
drawn as though they were all in the same plane so as to facilitate tracing the
circuits. Wires E¹ E' to E8 extend from the sides of the switch-board to the top,
and are in electrical communication with metal plates F1 F to F8 which are
arranged upon the top of the switch-board. I will now describe the manner in
which electrical communication is made between the wires E' E² to E8 and the
plates F F to F and other features of the top of the switch-board with special
reference to Figures 3, 4 and 5. The wires E¹² etc are connected by binding
screws or otherwise to metal strips a' a' etc which impinge against metal
strips 66 etc leading to the plates F¹ F' etc. These plates F1 F2 etc are fastened
in pairs by screws or other suitable means to dovetail blocks of wood c which fit in
dovetail grooves in wooden bars or strips d. Pairs of tumblers or levers G¹ G³, made

page_text: of metal are pivoted to one of each pair of blocks c and are drawn towards each
other below their pivots by springs e connected to plugs of insulated material to
prevent the electric currents passing along the springs from one tumbler to another.
These springs, by drawing the lower ends of the tumblers towards each other force
the upper ends of the tumblers away from each other and cause metallic spring-
like portions arranged at the upper ends to make contact with the plates F¹ F³ etc.
Normally contact will be maintained in this manner between the tumblers G¹ G'
and the plates F F etc. The electric circuit is then continued from the tumblers
G¹ G² etc to contact pieces H¹ H³ etc thence along wires I' I' etc to the sides of the
switch-board and thence along wires J' J' etc to the electro-magnet belonging to
one of the diaphragms of the multiple receiver.
It will be seen from this description that the subscribers' telephone instruments
are normally connected in pairs with the multiple receiver. To illustrate this the
circuit between subscribers' A¹ A will be followed. From the ground of the
telephone instruments of subscriber A¹ the circuit extends through the instruments,
thence along the wires D' E' and strips a¹ b₁ to the plate F¹ of the switch-board
thence through the tumbler G¹ to the contact piece H₁ thence along the wire 1' to
the multiple receiver and along the wire I, to the contact piece H³ and tumbler G³
to the plate F thence along the strips 6' a' and the wires E* D* to the instruments
of subscriber A² and thence to the ground of the latter The whole of the
subscribers are thus connected in pairs and the plates F¹ F¹ are numbered in
accordance with the numbers of the subscribers. These plates are preferably
arranged so that adjacent plates will bear successive numbers to facilitate finding
the plates when wanted." This order has been departed from in the diagram
Figure 1 merely for convenience in illustration and description
The multiple receiver is suspended by rods or other suitable means from a
support above the table as indicated in Figures 6 and 7. It comprises a number
of diaphragms K and appurtenances attached to a common body-piece K₁ This
body-piece has one vertical passage K' and a number of radial passages K³ com-
municating therewith. At the ends of these passages are chambers K* containing
electro-magnets K' and the diaphragms K. It will be seen that the electro-
magnets K³ are opposite the centres of the diaphragm K. The chambers K* com-
municate with the passages and the diaphragms are arranged close to the passages.
Sounds emitted from any of the diaphragms will pass through the passages to the
lower end of the vertical passage K. At the said lower end is a flexible tube
which may be made of india-rubber and is connected to a head piece Ko. This head
piece comprises branch pipes terminating in sections of flexible material provided
with ear pieces. Between the ear pieces extends a strip of flexible material such
as metal or hard india-rubber adapted to fit the head of the operator The operator
sits at the switch board with this head piece applied to his head and hears any
orders which may be given to him by the subscribers. The flexible tube whereby
the head piece is connected to the vertical passage K' affords provision for motions
of the bead of the operator and the flexible terminal sections of the head piece
conduce to the same result The operator never needs to change his position to
listen at the multiple receiver when it is thus arranged.
The electro-magnet belonging to each diaphragm has three separate and inde-
pendent coils of wire as shown in Figure 9. Each coil has a pair of subscribers'
wires connected to it hence every one of the electro-magnets and its diaphragm
serves for six subscribers. The ends of these coils are connected with binding
screws on the head piece of the multiple receiver and to these binding screws are
secured the wires JJ' etc. Attached to this head-piece is a drum which surrounds
and encloses the body-piece K¹ and the chambers K.
When the operator hears an order he learns which subscriber, is giving the order,
by the subscriber calling out his number. The order may be simply "A' on A"."
In such case the operator has merely to make the necessary connections to place
the subscribers in communication. To accomplish this he takes a pair of metal
plugs Land inserts one of these plugs in the plate F¹ of subscriber A' and the

page_text: -
other in plate F3 belonging to subscriber A³. There are a number of pairs of these
plugs L adjacent to the switch-board and they are connected to wires L' L³ which
pass round pulleys attached to weights L' as shown in Figure 2 so that the wires
and plugs will be drawn down and kept down when not in use. This expedient is
adopted merely to ensure the plugs going automatically to their proper places and
being kept there when out of use. The insertion of the plugs L in the plates F¹ F³
causes the tumblers Gland G³ to break contact with the plates F' and F3 and to
press against metal rods M which extend between each pair of tumblers and
connect with a wire M¹ which is common to all and leads to the ground. The
plugs L do not make electrical contact with the tumblers but act against insulated
buttons with which the tumblers are provided. The result of making contact
between the tumblers G¹ G³ and the rods M is to establish electrical communi-
cation between the subscribers A and A' and the ground without cutting them off
the multiple receiver. To be more explicit the circuit of subscriber A³ will then
pass from his instruments along the wires D* E* and strips a b' to the plate F²
thence along the tumbler G2 contact piece H and wires I J' to the multiple
receiver, thence along the wires J¹ I to the contact piece H¹ along the tumbler Gl
to the rod M with which it is in contact and thence along the wire M to the
ground. In a similar manner the subscriber A' is connected through the multiple
receiver to the ground. The insertion of the plugs L in the plates F' F³ forms as
it were a bridge between these plates or in other words forms a connection between
the subscribers A¹ A³. A detailed description of the manner in which this is
erected will now be given. Each of the wires L' extends to a binding screw f and
thence a wire L' extends to the metallic front frame of an annunciator drop N.
This front frame is insulated from the main frame of the annunciator has hinged
to it a plate g in such a manner that when this plate is released from a
catch g¹ it will fall forward upon a metal seat on a bar O of insulating material.
When the plate g is held up by the catch, the electric current passes through
it to a metal spring g², thence to the main frame of the annunciator, thence
to the coils of an electro magnet g³, comprised in the annunciator thence along
a vire L to a metal plate h, thence to a plate h¹, which is in contact with
the plate h and thence to a plate h which is also in contact with the plate /'
From the plate h² a wire Le leads to a binding screw f' with which one of the
wires L is connected It will be seen that in this manner the coils of the electro
magnet g which is comprised in the annunciator drop in circuit. The electric
current by which sound is transmitted is not sufficiently strong to operate the
electro-magnet g³ hence the catch g¹ will maintain the plate g in its upright
positions. This catch g¹ consists of a lever pivoted between the ends and having
at one end a hook which is adapted to engage with the plate g when the latter is
raised. Its other end extends over the electro magnet and constitutes an
armature therefor. When the electro magnet acts upon it the hook is disengaged
from the plate g and the latter falls forward. A spring g holds the hooked end
downwards when the electro magnet does not operate upon the other end and thus
the hook is kept in condition to hold up the plate.
After connecting the two subscribers the operator notifies them of the fact that
they are connected. This he does by pressing the plate ' down upon metal
plates h³ h and breaking its connection from the plates h h². A wire L' extends
from the binding screw f to the plate ³ and a wire L' extends from the plate h* to
the binding screw f'. A generator or battery P having one pole connected with
the ground as the other pole connected by a wire P¹ with a metal push button
whereby the plate h¹ is operated, hence when the plate is depressed electrical
communication will be established between the wires P L' and L³ whereupon the
electric current from the battery P divides and passing along the wires L' L³ to the
plates F F and thence to the bells of the subscribers A¹ A³ sounds a signal
When the subscribers A¹ As have finished their conversation they press a key or
otherwise send over their circuit an electrical current of sufficient electro-motive
force to energize the electro-magnet g of the annunciator drop which is in circuit

page_text: with them.
The catch g' will thereby be released and will fall forward on its
metal seat on the bar Ŏ thus signalling the operator. When the plate 9 falls
forward a push piece with which it is provided presses back the spring g³ so
that it will no longer be in electrical contact with the front frame of the
annunciator. A wire Q extends from the seat on which the plate g drops to a coil
of one of the electro magnets K³ of the multiple receiver and a wire Q' extends
from such coil to the plate h² hence when the subscribers signal to the operator by
dropping the plate g they also throw into their circuit one of the electro-magnets
of the multiple receiver; the circuit then extends from the wire L' to the wire L'
thence to the front frame of the annunciator, thence over the plate g to the seat
upon which it drops thence along the wire Q to the multiple receiver thence along
the wire Q to the plate h* thence along the wire L, and thence to the wire L³.
The operator can then hear anything which the subscribers desire to say to him
Should the operator desire to converse with a subscriber he can do so through
a telephonic transmitter R which is hung on a rod R' having a swivelling con-
nection with the multiple receiver. When he desires to converse with a subscriber
he inserts in the plate F" or F2 etc of the subscriber a plug S which is connected by
a wire R with the transmitter R whereupon a circuit will extend from that
subscriber's plate F¹ or F2 etc to the plug S along the wire R2 to the transmitter
thence along a wire R³ from the transmitter to a coil of one of the electro magnets
of the multiple receiver and thence along a wire R' to the ground
Having thus fully described the said invention as communicated to me by my
foreign correspondents and the manner of performing the same I wish it understood
that I claim
First In a telephone exchange system, the combination of a number of sub-
scribers' service lines with a multiple telephonic receiver at a central office normally
in circuit with the service lines, a single telephone transmitter at the central office
normally out of circuit, and means whereby this telephonic transmitter may be put
in circuit with any of the service lines, substantially as specified.
Second In a telephone exchange system, the combination of a number_of
subscribers' service lines with a multiple telephone receiver at a central office
normally in circuit with the service lines, a single telephone transmitter at the
central office normally out of circuit, and a switch-board whereby different service
lines may be put in circuit with each other or with the telephonic transmitter,
substantially as specified.
Third In a telephone exchange system, the combination of a number of sub-
scribers' service lines and a multiple receiver located at a central office having
a number of diaphragms and electro-magnets, and a sound passage common to all,
substantially as specified.
Fourth In a telephone exchange system, the combination of a number of sub-
scribers' service lines and a multiple receiver located at a central office baving a
number of diaphragms and a corresponding number of electro-magnets arranged
opposite the centres of the diaphragms and severally provided with a plurality of
coils, substantially as specified
Fifth In a telephone exchange system, the combination of a number of sub-
scriber's service lines, and a multiple receiver at a central office suspended over the
position occupied by the operator, substantially as specified.
Sixth In a telephone exchange system, the combination of a number of
subscribers' lines and a multiple receiver at a central office suspended over the
position occupied by the operator, and having a head piece for the operator,
substantially as specified.
Seventh In a telephone exchange system, the combination of a number of
subscribers' service lines and a multiple receiver at a central office suspended over
the position occupied by the operator, and having a sound-passage terminating in
a head-piece provided with sound-passages adapted to lead to the ears of the
operator, substantially as specified.

page_text: Eighth In a telephone exchange system, the combination of a number of sub-
scribers' service lines and a multiple receiver at a central office suspended over the
position occupied by the operator and having a flexibly connected head-piece for
the operator, substantially as specified.
Ninth. In a switch-board, the combination of the plates F¹ F etc, the dovetail
blocks c and the bars or strips d, substantially as specified.
Tenth. In a switch-board, the combination of the plates F F etc, and the
tumblers G1 G2, etc, substantially as specified.
Eleventh In a switch-board, the combination of the plates F¹ F' etc, the
tumblers G¹ G³ etc, and the rods M, substantially as specified.
In witness whereof I the said William Robert Lake have hereunto set my
hand and seal this first day of March in the year of our Lord One
thousand eight hundred and eighty three
1173 DODT TATZE