Year: 1895

page_text: Date of Application, 5th Nov., 1895-Accepted, 21st Dec.; 1895
A communication from abroad by WILLIAM H. NIXON, of 115, Transit Street,
Providence, Rhode Island, United States of America.
I PHILIP MIDDLETON JUSTICE of 55 and 56 Chancery Lane in the County
of Middlesex Fellow of the Chartered Institute of Patent Agents 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 :-
The main object of this invention is to enable communication to be effected not
only between terminal stations of an electric system but also from one or more
intermediate points. The arrangements being such that when the terminal stations
are in communication it is impossible for the communications to be heard at the
intermediate points although a portion of the same system of wires is employed
for both communications.
From the foregoing it will be seen that the invention will be particularly useful
for railway systems and for other uses where it is sometimes extremely desirable to
be able to communicate promptly with a terminal station.
To enable the invention to be fully understood reference is made to the
accompanying drawings in which
Figure 1 shows the arrangement of the wires employed, communication being
effected by means of telephones; and
Figure 2 is a view of a single post on the line of a railway or other electric
system showing the manner in which the open loop wires of one of the sub-stations
of Figure 1 may be arranged upon the poles.
By a reference to Figure 1, it will be seen, that, as there shown and as it is
between
preferred to construct it, there are three essential parallel wires a, b, and
the terminal stations at X and Y, at which terminal stations are located the
telephones S and T respectively. One of these wires, as c, is connected at either
end to one pole of each of the terminal telephones. Each of the other wires,
as a and b, are connected at one end to the other pole of one of the two terminal
telephones so that only one of these wires is normally connected with either of
these telephones, the other end of each of these wires being left normally open.
Thus wire is connected to telephone S at the opposite pole to that to which is
attached wire c, and running thence down the line finally ends in the normally open
switch or circuit breaker d at the other station Y. In a similar manner the third
wire a is connected to the terminal telephone T at the opposite pole to which is
attached the common wire c, and after proceeding to the opposite station X ends
in the similar normally open switch d. Both these switches and d¹ are preferably
constructed to automatically break the circuit except when intentionally closed, as
for example by means of a spring actuated push button. When closed they form
electrical connections respectively with those poles of the two terminal telephones
to which the common wire c is not attached, either by connecting with the other
normally open wire before it reaches the telephone as shown in the drawings or in
any other way preferred to effect the same result.
From each of the wires a and b at various points along the system and as
numerously placed as desired extend branch wires g and g' in pairs preferably carried
down the poles A (Figure 2), upon which all the wires of the system are strung, as
shown in Figure 2, each pair of wires terminating at any convenient height from

page_text: the ground at the points and ', these letters representing any convenient means
by which portable apparatus for communications is to be attached. These
points and must not be in electrical connection one with the other except when
connected through such apparatus. When the portable instrument as S is con-
nected with any pair of these branch wires it evidently becomes electrically
connected as in multiple with the wires a and b.
The operation of the system is as follows:-In case the guard of a wrecked
train, a track inspector, or other person, desires to communicate with the
stations X and Y through the telephones S and T at those stations, he connects a
portable telephone as S, with the pair of branch wires g and g' at the points h h',
at the nearest sub-station and at once communicates with both terminal stations,
the sound undulations traveling the following course; through one of the branches g
to line a and by that line to telephone T; thence, the switch d being open, by
line c to and through telephone S, and thence by line back to that branch wire g
connected with the sub-station used. It will be seen that the sound undulations
thus traverse in both directions the entire distance between the terminal stations by
means of the metallic circuit thus established. But not only this, but it traverses
practically no more than this circuit, at whatever point the portable telephone is
inserted, since as the length of one of the wires a or bis increased as one passes
along the line the length of the other of these is decreased to the same extent, one
portion of both wires from any given place of communication being a dead wire
when used in this way. Accordingly whatever sub-station is used, be it one mile
or fifty miles from either end, the resistance of the line is always the same.
The switches d and d' are used for ordinary communication between the terminal
stations. As the system is shown in Figure 1 no communication is possible between
these terminal stations, but by either operator closing the connection at his own
end of the line he at once establishes a closed circuit to the other end passing
through both terminal instruments only. Thus the operator at Y by closing the
switch d, has the metallic circuit composed of wires c and b in which both
telephones S and T are included in series, and the operator at X by closing has
in a similar manner the circuit composed of wires c and a; and if both d and d'
are closed at the same time no harm is done. Thus the same system of wiring
will serve for communication between the terminal stations themselves and also
between any one of a number of sub-stations along the line and both the terminal
stations. But this is not all. Two further points deserve attention;
First-
-That the resistance of the circuits between the terminal stations X and Y
either by line a or line b is always the same as that from any one of the sub-stations,
and two of the instruments are always the same. Accordingly it is impossible for
any user of one of the sub-stations to make the excuse that he was too far away
to make himself heard. The answer would be that the resistance of the circuit is
no greater than that in constant use between the terminal stations.
Second-That the closing of either switch or circuit breaker d or d¹ of itself
destroys all communication between any sub-station and the terminal stations and
renders it impossible for any person at any one of the sub-stations to overhear any
conversation carried on by means of the terminal telephones, since it short-circuits
this entire system. Thus assume the switch d¹ to be closed, and a portable
telephone S connected to any one of the sub-stations. Now upon speaking into
this portable instrument the sound undulations will travel the path of the least
resistance, and will simply pass by the wire a and switch d' back by the wire b
without passing through the telephone S. And in the same manner if switch d is
closed, the undulations will not pass through telephone T. It is only when these
switches are open that the undulations are compelled to pass through the greater
resistance of the terminal instruments. In the same way upon the operator at
either end closing his switch to communicate with the operator at the other.end,
his circuit is always made up in part of wire c which has no connection with any
of the sub-stations and thus no conversation between the terminals can reach the
sub-stations. Even if both switches happen to be closed at the same time, yet the

page_text: only wires having any connection with the sub-stations, viz. a and b both connect
with the same pole of each terminal telephone and accordingly any instrument
inserted between them must remain unaffected by those terminal instruments.
It is evident that the wire c may be replaced if desired by ground connections
at the terminal stations. A metallic circuit is however very much to be preferred
and is alone shown in the drawings. It is also evident that any other means of
electrical communication may be used with this system of wiring in place of
telephones, the latter particularly in the magneto form being however preferable
from the absence of batteries necessary for instruments of other kinds, and batteries
being objectionable from their weight, danger of breakages &c. It is further
evident that it is not necessary to confine the system to two instruments, one at
either terminal, but any number desired may be inserted in line c without affecting
the invention; and if it is at any time desired one of these terminal instruments
may be omitted. Nor is it necessary that the invention should be confined to
railway uses.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed as communicated to
me by my foreign correspondent I declare that what I claim is
1. A system of wiring for electrical communication which consists of two
conductors each normally electrically open in one direction but at opposite ends of
the system, means at various points along said conductors by which an instrument
for electrical communication may be inserted between them, an electrical connection
between the other ends of said conductors, one or more instruments for electrical
communication inserted in said electrical connection, and means for electrically
connecting one or both of said conductors at its normally open end with the other
of said conductors, as and for the purpose described.
2. A system of wiring for electrical communication which consists of three
essentially parallel conductors, two of which are each normally electrically open in
one direction but at opposite ends of the system, and the third of which connects
the other ends of said normally open conductors, means at various points along said
normally open conductors by which an instrument for electrical communication
may be inserted between them, one or more instruments for electrical communication
inserted in said third conductor, and means for electrically connecting one or both
of said normally open conductors at its open end with the other of said open
conductors, as and for the purpose described.
3. A system of wiring for electrical communication which consists of three
essentially parallel conductors, two of which are each normally electrically open in
one direction but at opposite ends of the system, and the third of which connects
the other ends of said normally open conductors, open branch loops at various
points along said normally open conductors by which an instrument for electrical
communication may be inserted between said conductors, one or more instruments
for electrical communication inserted in said third conductor, and means for
electrically connecting one or both of said normally open conductors at its open end
with the other of said open conductors, as and for the purpose described.
Dated the 5th day of November 1895.
PHILIP M. JUSTICE.