Improvements in Direct Call Telephone Systems.
Year: 1895

page_text: Date of Application, 24th May, 1895
Complete Specification Left, 19th Mar., 1896-Accepted, 23rd May, 1895
Improvements in Direct Call Telephone Systems.
THOMAS SLOPER of 11, 12, 14 & 15 Brittox Devizes in the County of
Wiltshire House Furnisher do hereby declare the nature of this invention to be as
follows:-
This invention relates to certain improvements in electrical communicating
apparatus & my complete system consists of a series of telephones connected in a
particular manner by signalling apparatus & special switches so that a person at
any one telephone instrument may communicate with a person at any other
instrument in the system.
In carrying out my invention I use a series of main line wires equal in number
to the number of telephone stations & also a return wire which is generally only
used for signalling purposes.
At each station I employ an instrument consisting of a telephone, switch, signal
bell and a signalling apparatus.
The switch may be of any desired form but for convenience I prefer to use a
metal arm turning upon one end & so arranged that the other end may be brought
into contact with studs or springs in electrical connection with the lines apertaining
to the other stations.
In addition to the above described switch I employ the usual "switch hook"
upon which the receiver is hung when not in use the hanging up of which
disconnects the line wire from the telephone & connects it to the bell ready to
receive a call.
Each main line wire is connected to the switch hook of one instrument & to its
respective stud at the switches of all the other instruments.
When the receiver is taken off its hook the line wire is disconnected from the
bell & put in connection with the telephone in the usual manner. The second
terminal of the telephone is not connected to the earth or return wire as usual but
is connected to the switch arm or other apparatus for connecting to the lines of the
other stations.
From the above it will be understood that the telephone could not be used until
the switch arm at a "called" station is pointed to the number of the calling
station.
In order that the "called" station shall know what number to put his switch to
I use a special signalling apparatus which sends a number of currents to the
"called" station such number of currents corresponding to the number of the
calling station.
Thus suppose No. 5 wished to communicate with No. 3 he would put his switch
to No. 5 & operate his signalling apparatus which would ring 5 notes on the bell
at No. 3 station. Upon hearing this No. 3 would put his switch to No. and
operate bis signalling apparatus which would ring 3 notes at the calling station
intimating that the proper station was answering & that conversation could be
proceeded with. As there is a complete metallic circuit & as the return or "earth"
line is not used for conversation " cross-talk" is absolutely impossible.
The calling station can be sure that the right station is answering a call as he
can only talk to, or hear conversation from the station corresponding to the number
to which his switch is connected.
The person at the "called" station knows what station is calling him before

page_text: going to the instrument & the calling station receives a reply ring from the called
station.
It is impossible for any other station to ring up or in any way to interupt during
a conversation.
The ringing key is made of a special form so that when operated a number of
signals are given. In order that these may not follow each other too closely &
thus appear as one I sometimes use what I will call a retarding device to regulate
the transmission.
This may consist of a pendulum or rocking lever (usually operated by the press-
button) which may be caused to transmit a current to the line desired at each beat,
or after a certain number of beats. It will be understood that the object is to
transmit a certain number of electric signals & no more, or no less, each time the
ringing apparatus is operated & I do not confine myself to any particular arrange-
ment of the transmitting or ringing key as almost any of the devices used to regulate
or retard the movements of ordinary clockwork may be employed with modifications
to retard regulate or transmit the signals.
I prefer to arrange the ringing key so that in outward appearance it resembles
the ordinary push button but any suitable arrangement may be employed. Of
course an ordinary push button could be used for the purpose by pressing it the
requisite number of times, but as this would be liable to cause mistakes I prefer
that the signals shall be sent automatically by one movement of the ringing key.
In cases where a large number of stations are combined in one system Morse or
other signals may be used instead of numbers.
In some cases where it is only desired that a station may communicate with
certain other stations of a system the wires relating to the stations it is not required
to communicate with may be omitted from the instrument of such station.
I sometimes so arrange that the signal shall be given rapidly when the press
button is pushed in & that the same signal shall be repeated slowly afterwards when
the press button is returning to its original position.
In connection with the press button is a rack which when the button is pressed
in causes a pinion to revolve. In connection with this pinion is a hollow drum or
wheel (preferably lined with a nonresonant material such as rubber or felt) con-
taining some loose substance such as sand or shot. This loose substance does not
fill the drum & its object is to retard or delay the return of the rack to its original
position.
A lever attached to the rack successively comes in contact with a number of
studs or projections suitably arranged according to the signal required, and each
time contact is made a current is sent to the line to which the switch is connected.
The button may be caused to return to its original position by a separate spring
to that employed to replace the rack so that the trausmission of the repeated signal
may continue after the finger is removed from the press button.
The switch hook may be so arranged that when the receiver is taken off its hook
the ringing apparatus is locked & cannot be used.
The ringing apparatus may be so arranged that the act of ringing causes the
microphone to be shaken or revolved in order to change the contacts of the carbon
or to transmit the signal (giving the number of the station) through the telephone
at the called station.
It will be obvious that the transmitting key or press button may be arranged to
ring several bells at once through different wires, or to ring a peal on a series of
bells having different tones.
One or more distant or outside telephone stations may be connected to the main
system by single line wires if desired. In this case I place a magneto bell of high
resistance between the line of the distant station & earth at one station on the main
system. At the distant station I provide an ordinary electric bell to be rung by a
battery current from any station in the main system & a magneto generator for
ringing purposes. By a modification a double line wire may be used to a distant
station.

page_text: Considerable modifications may be made in the arrangements described without
departing from the spirit of the invention.
Dated this lat dor of Now 1805
THOMAS SLOPER.
Improvements in Direct Call Telephone Systems.
I THOMAS SLOPER of 11, 12, 14 & 15 Brittox Devizes in the County of
Wiltshire 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 my invention relates to certain improvements in electrical communicating
apparatus and my complete system consists of a series of telephones connected in a
particular manner by signalling apparatus and special switches so that a person at
any one telephone instrument may communicate with a person at any other
instrument in the system.
In carrying out my invention I use a series of main line wires equal in number
to the number of telephone stations & also a return wire which is only used for
signalling purposes.
At each station I employ an instrument consisting of a telephone a switch, a
signal bell and a signalling apparatus.
The switch may be of any desired form but for convenience I prefer to use a
metal arm turning upon one end & so arranged that the other end may be brought
into contact with studs or springs in electrical connection with the lines appertaining
to the other stations.
>
In addition to the above described switch I employ the usual " switch hook
upon which the receiver is hung when not in use & the hanging up of which
disconnects the line wire from the telephone and connects it to the bell ready to
receive a call.
Each main line wire is connected to the switch hook of one instrument and to its
respective stud at the switches of all the other instruments.
When the receiver is taken off its hook the line wire is disconnected from the
bell & put in connection with the telephone in the usual manner.
The second terminal of the telephone receiver is not connected to the earth or
return wire as usual but is connected to the switch arm or other apparatus for
connecting to the lines of the other stations. From the above it will be understood
that the telephone could not be used until the switch arm at a "called" station is
connected to the number of the calling station.
In order that the "called" station shall know what number to put his switch to,
I use a special signalling apparatus which sends a number of currents to the
called station, such number of currents corresponding to the number of the calling
station.
Thus supposing No. 5 wished to communicate with No. 3, he would put bis
switch to No. 5 and operate his signalling apparatus, which would ring 5 notes on
the bell at No. 3 station.
Upon hearing this No. 3 would put bis switch to No. 5 & operate his signalling
apparatus, which would ring 3 notes at the calling station intimating to the person
there that the proper station was answering & that conversation could be
proceeded with.
As there is a complete metallic circuit & as the return or earth line is not used
for conversation cross-talk is absolutely impossible.
The person at the calling station can be sure that the right station is answering
a call as he can only talk to or hear conversation from the station corresponding to
the number to which his switch is connected.

page_text: The person at the called station knows what station is calling him before going
to the instrument & the calling station receives a reply ring from the "called
station which advantages are not attained by ordinary systems.
The ringing key is made of a special form so that when operated a number of
signals are given. In order that these signals may not follow each other too closely
& thus appear as one I sometimes use what I will call a retarding device to regulate
the transmission.
It will be understood that the object is to transmit a certain signal to indicate
what station is calling. I do not confine myself to any particular arrangement of
the transmitting or ringing key as many of the devices used to regulate or retard
the movements of ordinary clockwork may be employed with modifications to
retard regulate or transmit the signals.
I prefer to arrange the ringing apparatus so that in outward appearance it
resembles a magneto ringing apparatus or an ordinary press button.
Of course an
ordinary press button could be used for the purpose by pressing it the requisite
number of times, but as this would be liable to cause mistakes I prefer that the
signals shall be sent automatically.
In cases where a large number of stations are combined in one system Morse or
other signals may be used instead of numbers.
In the accompanying drawings like letters indicate like parts throughout.
A is the handle of the signal transmitting apparatus.
B is the switch for connecting to the lines of the other stations.
C is the secondary of the induction coil (Fig. 2).
D is the telephone receiver.
E is a spring which is electrically connected to the switch hook when the receiver
is unhooked.
F is the switch hook.
G is a piece of insulating material.
H is a piece of metal which connects the spring contacts I and K and thus closes
the circuit of the microphone when the receiver is unhooked.
L is the microphone."
M is the microphone battery.
N is the primary of the induction coil.
O is a spring or contact.
P is the bell (usually single stroke).
R is the common return or "earth" line.
S is the battery used for ringing purposes in connection with the signal transmitting
apparatus.
The signal transmitting apparatus shown as example in Fig. 2 consists of a
handle A connected with a wheel Y. This wheel is geared into a similar wheel W
having twice the number of teeth. Connected to W is the wheel X the arrange-
ment being such that two revolutions of the handle A causes the wheel X to revolve
once.
The wheel X has projections V which when revolving come into contact with
the spring T causing the latter to make electrical contact with the post U. The
projections V correspond in number & are arranged in position according to the
signal to be given thus for No. 3 station there would be three such projections on
the wheel X which would send 3 signals each time the handle A is turned twice
round.
I prefer to so arrange that the signal is sent during one revolution of the handle
& no signal is sent during the next revolution as this causes a pause between each
complete signal. This apparatus slowly repeats the signal over & over again so
long as the handle is turned.
I usually employ a single stroke bell for receiving the signal.
I find this form of apparatus very convenient, as the person at the calling station
has only to turn the handle slowly round several times or until he receives a reply
signal from the "called" station."

page_text: Fig. 1 shows a telephone system of 4 stations with microphone circuits omitted.
No. 4 station is shown in position for calling No. 2 and No. 3 is shown as in
conversation with No. 1 station.
Fig. 2 shows the connections for an instrument with microphone circuit.
No replacement of the switch is necessary after a conversation.
The contact post U may be omitted from the signal transmitting apparatus & the
circuit may be closed by the projections V coming into contact with the spring T.
It will be understood that I do not confine myself to any particular form of
signal transmitting apparatus. Considerable modifications may be made in this
system without departing from the spirit of the invention.
Having now particularly described & ascertained the nature of my said inven--
tion & in what manner the same is to be performed, I declare that what I
claim is,-
"
1. A telephone instrument of the class described in which the home line is.
connected through the telephone receiver to the switch & thence to the distant
station without coming into electrical contact with the ".
"earth or common return
wire by the operation of taking the receiver off its hook & the home line is
connected to the bell by the operation of hanging up the receiver substantially as
described.
2. In a telephone instrument of the class described a switch hook arranged in.
such a manner that it connects the home line with the bell when the receiver is
hung up & so that when the receiver is removed it disconnects the bell & connects
the switch to the home line through the telephone & without electrical connection.
with the earth or return wire substantially as described.
3. A telephone system of the class described in which the calling or signalling
current passes through a circuit formed by the line of the called station & the
common return wire & in which the common return wire is cut off by the operation
of unhooking the receiver and at the same time the speaking circuit is formed
through the lines of the "calling" & the "called " stations respectively substantially
as described.
4. A telephone instrument of the class described in which the line wire is cut off
from the bell & from electrical connection with the earth or return wire by the-
operation of unhooking the receiver & is at the same time connected through the
telephone to the switch or other device for connecting to the line wires of the other
stations substantially as described.
5. In a direct call telephone system of the class described the use of automatic
or mechanical transmitting apparatus for transmitting a predetermined & different
signal from each station such signal being transmitted through a circuit formed by
the line appertaining to the called station & the return or earth wire substantially
as described.
6. An intercommunication telephone system in which each station is provided
with a distinctive signalling apparatus to enable the "called" station to distinguish
from where the signal came, each instrument being so arranged as to cut out the
common return line & to form the speaking circuit through the lines appertaining
to the "calling" and "called " stations respectively substantially as described.
7. The combination and arrangement of parts constituting the complete
telephonic system substantially as described and illustrated in the accompanying
drawings.
8. The combination & arrangement of parts constituting the complete telephonic
switch board apparatus substantially as described & illustrated in Fig. 2 of the.
accompanying diawings.
THOMAS SLOPER.