Improvements relating to Electric Signalling in Open Circuits.
Year: 1895

page_text: This Print is in accordance with the Original Specification as it stands after
Amendment (under Section 11 of the Patents, &c. Act, 1883), as required by
the decision of the Comptroller General of the 18th day of May 1896.
Date of Application, 12th Oct., 1895-Accepted, 16th Nov., 1895
COMPLETE SPECIFICATION (AMENDED).
Improvements relating to Electric Signalling in Open Circuits.
I, JOSEPH RAYNER GIBSON, of 42 Hill Rise, Richmond, in the County of
Surrey, Telephone 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 electric signalling in open circuits. It is particularly
applicable to the utilization for telephonic purposes of electric bell circuits or other
open circuits, and is especially suitable for electric signalling systems where there
are a number of circuits having a common return lead. The said invention is
applicable whether such common return lead be a metal conductor or " earth."
The great utility of my invention resides in the fact that it provides for effecting
a call at the station or position where the circuit is broken. For example it allows
of transmitting signals to any outlying station such as a fire alarm point or the like
where the circuit is normally broken.
For this purpose I use an exhausted tube or bulb provided with a pair of
separated conductors in series with a signalling instrument and with means for
producing an induced current that will leap the interval between the said conductors
and thus operate the signalling instrument to effect the desired signal.
In the accompanying drawings which illustrate my invention as applied by way
of example to an electric bell system.
Figure 1 illustrates the bell system containing three circuits having a common
return.
Figure 2 illustrates the application of my invention to the said bell system in
such a manner as to make use of the bell circuit battery for working the telephone
and the call apparatus.
Figure 3 shows a modification wherein extra batteries are introduced one for
working the telephone and one for working the induction apparatus used for making
the call from the central position.
Figure 4 shows a further modification wherein one battery works the bell circuit
and the telephone and another works the said induction apparatus.
Figure 5 illustrates another modification hereinafter described.
Referring to Figures 1 and 2, A', A', A' denote the gaps in the circuit, which
gaps in this instance exist at the bell pushes; B is the battery; C is the bell;

page_text: D' D D are the indicators. The leads are connected up in the usual manner.
With such a system it will be seen that it is not feasible to introduce bells
to directly bridge over the gaps represented by the pushes as the current from the
battery would split up and pues through the several circuits which would
collectively have a very low resistance and hence the battery would quickly
become exhausted,
In applying my invention to such a system I introduce into the same in connection
with ench gap A', A', A' (or with as many of them as it is desired to fit with
telephones) a telephone consisting of a transmitter T and a receiver R Figure 2 the
lends from which are connected in parallel with the circuit closing key or push at
the gap in the circuit. I have shown one such telephone applied to the gap A¹.
Moreover in the position usually occupied by the call bell of the telephone
I introduce an exhausted tube or bulb E in which are fitted two separated conductors.
A small Geissler tube or an incandescent lamp with the filainent broken will
answer the purpose very well. One conductor of the tube or bulb is connected to
one contact stud of an automatic switch F which is connected to one terminal of
the push or key at the gap A' and the other conductor of the tube or bulb E is
connected to the telephone at a point between the transmitter and the receiver, and
in series with the receiver. Any current therefore to be sent through the line must
have sufficient potential to leap the gap between the separated conductors in the
tube or bulb E. On the removal of the receiver from the book of its automatic
switch the latter is caused by its spring in the ordinary manner to make contact
with the other contact stud of the automatic switch which stud is connected as
usual to the transmitter, so that the bulb E is thereby cut out of circuit and the
transmitter is thrown in circuit. The instrument denoted by the drawing is of the
direct working type of which there are many modifications. My invention is
however equally applicable to any type of electrical telephone, the essential
requirement being that a call may be made to a distant position where the circuit
js " open "-the "break" in the circuit being such that an ordinary battery
current cannot pass it. This requirement is fulfilled by so arranging that the
vacuum bulb or tube E is in series with the receiver when the latter is in its normal
position resting on the hook.
The apparatus for "calling" from the central station comprises a plug switch
board having as many holes as there are stations in the system and denoted in a
general way by G, a telephone denoted by the transmitter T' and receiver R', and
an induction coil, denoted in a general way by H, or any suitable apparatus such
as a magneto-generator for producing an induced current of high potential.
Ench hole in the switch board is furnished with contacts, g normally in
electrical connection but so arranged that they can be separated and the ordinary
bell circuit through them thereby broken by the insertion of a plug J which is
connected by a flexible cord with the automatic switch K. This plug is so guided
by the socket in which it is introduced that it raises the spring contact o' but does
not come into electrical connection with the contact g. A circuit is thus formed
from this point through the receiver R, bulb E, switch F, the common return of the
bell circuit, the fine wire of the induction coil H, and the switch K back ria the
flexible cord and plug to the spring contact g'. This circuit is broken by
the gop between the separated conductors within the bulb E, but when the contact
key of the induction coil is depressed the induced current in the wire is
sufficiently powerful to leap the said gap in the bulb E and thus traverse the
circuit. To effect a call therefore from the central station the plug J is inserted
into the socket of the line required, and the contact key of the induction coil is
then depressed whereupon the make and break contact of the induction coil will
vibrate rapidly and will thus cause a buzzing sound to be emitted by the receiver R
at the called station. After thus pressing the key the operator should immediately
apply the receiver R' to his ear and he will then hear with sufficient distinctness
the tell tale "clicks" produced by the person at the other station when he presses

page_text: his push A or removes his receiver R from the switch F, either movement serving
to complete the circuit by cutting out the bulb or tube E.
It is not however necessary that the operator should wait with the receiver R¹-
applied to his ear, he may instead withdraw the plug J whereupon on a reply from
the distant station being given, the bell C will ring and the indicator be actuated
in the ordinary manner. The operator will then re-insert the plug, and speak.
A call from one of the distant stations represented by the gaps A', A', A³ is
denoted by the indicators D', D2 D³ together with the ringing of the bell C in the
ordinary manner, it being previously arranged that a different signal shall be given
when the telephone is to be used, than that given when it is not to be used, for
instance one ring may denote that the telephone is to be used and two rings that
the servant is wanted to attend on the person who calls.
The separated conductors in the tube or bulb E above referred to are insulated
from each other by the glass of which the said tube or bulb may be formed and
through which they pass; they are permanently separated within the exhausted
tube or bulb, but have suitable outer ends to which the other conductors are
connected. The induction coil, as shown in Figure 2, is worked by a portion only
of the battery B that is employed for calling from the various stations, and for
working the telephones. Two of these stations, it will be seen, are in series with.
the battery when one of the outlying stations is connected for speaking with the
central station. 1 may however use separate batteries for working the call
apparatus and the telephones in which case the connections will be modified.
Figure 3 shows the connections of a systein wherein a battery B is used for working
the bell C, a second battery B' for working the telephone and a third battery B³
for working the induction apparatus. Figure 4 illustrates the connections when a
separate battery B is used for working the induction apparatus, and another
battery B is used for working the bells and the telephones.
Although I have described a system wherein I use the receiver R for effecting
the call from the central to the distant station I may use a Mackenzie sounder or
other signalling instrument that will answer the purpose, taking care that such
instrument is placed in series with the exhausted tube or bulb E. Such an
arrangement is illustrated in Figure 5 wherein M represents a Mackenzie sounder
or an old telephone receiver, and the automatic telephone switch or other two-
way switch. By this arrangement the induced current for making the call from
the central station is passed through the instrument M and not through the
telephone receiver.
When I use a Geissler tube for the purposes of my invention the illumination in
said tube caused by the passage of the current may be utilized for signalling
purposes either separately or in conjunction with an apparatus for emitting sound
such as that above described. By suitably reversing the primary current at the
central station or position the visible signals may be changed and thereby readily
utilized by the code or Morse systems.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I wish it to be understood
that I am aware of Hodgson & Edward's application No. 11,748/95 and do not
claim anything which may be held to be within the Patent granted upon that
application. I declare that what I claim is :-
1. In an open electrical circuit an exhausted tube or bulb furnished with suitable
separated conductors included in series with a signalling instrument and arranged
in parallel with a circuit closing key, in combination with an induction coil or other
apparatus for producing an induced current that will leap the gap or space existing
between the aforesaid separated conductors, substantially as, and for the purpose,
specified.
2. The employment of Geissler tubes, or of incandescent lamps having broken
filaments, substantially as described, and for the purpose specified.

page_text: 3. The apparatus or means for enabling signalling to be effected in open electrical
circuits substantially as described with referenco to one or other of the arrangements
illustrated in the accompanying drawings.
Dated this 12th day of October 1895.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.