TELEPHONIC AND ELECTRIC " IMPROVEMENTS IN of APPARATUS FOR 1-m AND E COMMUNICATION AND IN CONNECTING THE LINE WIRES TO EARTH.
Year: 1880

page_text: LETTERS PATENT to John Norcross Culbertson, M.D., of Antwerp, in the
Kingdom of Belgium, at present residing at the Holborn Viaduct Hotel,
in the City of London, and James Wallace Brown, of No. 170, Upper
Kennington Lane, in the County of Surrey, Electrician, for an Invention
TELEPHONIC AND ELECTRIC
" IMPROVEMENTS IN
of
APPARATUS
FOR
1-m
PROVISIONAL SPECIFICATION left by the said John Norcross Culbertson
and James Wallace Brown at the Office of the Commissioners of Patents on
the 6th December 1880.
JOHN NORCROSS CULBERTSON, M.D., of Antwerp, in the Kingdom of Belgium,
at present residing at the Holborn Viaduct Hotel, in the City of London, and
JAMES WALLACE BROWN, of No. 170, Upper Kennington Lane, in the
" IMPROVEMENTS IN APPARATUS FOR TELEPHONIC
County of Surrey, Electrician.
AND ELECTRIC COMMUNICATION AND IN CONNECTING THE LINE WIRES TO
EARTH.'
> "
This Invention has for its object improvements relating to telephonic and other
systems of electrical communication, and the improvements relate more especially
to systems of electrical communication where a number of distant stations or offices
are all connected by wire with one central station at which the wire coming from
one station can be coupled up with the wire from any other station, and the two
stations thus put into direct electrical communication with one another.
It is well known that when any two wires are in proximity to one another and
connected to earth in the usual manner at their extremes, and an electrical current
is transmitted over one wire there is another momentary current set up in the
other, the effect being that this momentary current in the latter wire affects most
instruments, especially the telephone, in a more or less degree, and the telephone to
such an extent that one is able to hear any conversation that may take place over
the former wire.

page_text: To obviate this resort has been made to cabling or bunching a great many wires
together, each of which has been heavily insulated (in this case necessarily so) and
therefore very expensive. Now we also propose to cable or bunch wires together,
but we avoid the necessity of using a great number of wires of heavy insulation to
reduce the effects of induction and are enabled to use wires lightly insulated,
sometimes indifferently so, and to use indifferently either cables consisting of two
wires, or many, so reducing the expense, and at the same time we enable two
persons to converse over any one wire without fear of their conversation being
heard by any person listening upon a second wire.
Now as is well known with a cable of wires lightly insulated there would be
considerable induction of the wires at the ends of the cable were all connected to
earth in the usual manner but if all wires or conductors in the cable are at each
end of the cable conducted through instruments to independent "earth plates" or
"earths," that is, that each wire is connected through its instrument to earth
independently of all the other conductors, so that there shall be an isolated earth
plate for each conductor, then a conversation carried on along one wire cannot be
heard by any person listening on any of the other wires.
We therefore at the central station make provision for coupling each wire
(through the call instrument with which it is connected) to a separate earth, and
also at the opposite or outer end of the cable where the several wires are led away
to various offices. or stations we couple the several wires through instruments to
separate and independent earth plates which have no metallic connection one with
the other.
In addition to making provision for coupling each wire to a separate earth at
the central and outlying stations, we also arrange the commutator or coupling
'board at the central station in such a manner that when any one wire is coupled
to any other wire, they may also be coupled to an independent earth plate preferably
through a resistance coil.
If at the central station a separate earth connection cannot be obtained we plant
an earth plate of considerable area, and. then convey our earth wires to this plate,
and in such manner that there can be no escape or communication between the
several different wires until they are actually brought together by means of the
earth plate under ground.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Norcross Culbertson and James Wallace Brown in the Great
Seal Patent Office on the 3rd June 1881.
JOHN NORCROSS CULBERTSON, M.D., of Antwerp, in the Kingdom of Belgium,
at present residing at the Holborn Viaduct Hotel, in the City of London,
and JAMES WALLACE BROWN, of No. 170, Upper Kennington Lane, in the
County of Surrey, Electrician. "IMPROVEMENTS RELATING TO TELEPHONIC AND
OTHER SYSTEMS OF ELECTRICAL COMMUNICATION.".
This Invention has for its object improvements relating to telephonic and other
systems of electrical communication, and the improvements relate more especially
to systems of electrical communication where a number of distant stations or offices
are all connected by wire with one central station, at which the wire coming from
one station can be coupled up with the wire from any other station, and the two
stations thus put into direct electrical communication with one another.
It is well known that when any two wires are in proximity to one another and
connected to earth in the usual manner at their extremes, and an electrical current
is transmitted over one wire, there is another momentary current set up in the
other, the effect being that this momentary current in the latter wire affects most
instruments, especially the telephone, in a more or less degree, and the telephone to
such an extent that one is able to hear any conversation that may take place over
the former wire.
To obviate this resort has been made to cabling or bunching a great many wires
together, each of which has been heavily insulated (in this case necessarily so) and
therefore very expensive. Now we also propose to cable or bunch wires together,
but we avoid the necessity of using a great number of wires of heavy insulation
to reduce the effects of induction, and are enabled to use wires lightly insulated,
sometimes indifferently so, and to use indifferently either cables consisting of
two wires, or many, so reducing the expense, and at the same time we enable two
persons to converse over any one wire without fear of their conversation being
heard by any person listening upon a second wire.
Now as is well known, with cable of wires lightly insulated, there would be
considerable induction if the wires at the ends of the cable were all connected to
earth in the usual manner, but if all wires or conductors in the cable are at each
end of the cable conducted through instruments to independent "earth plates" or
"earths," that is, that each wire is connected through its instrument to earth
independently of all the other conductors, so that there shall be an isolated earth
plate for each conductor, then a conversation carried on along one wire cannot be
heard by any person listening on any of the other wires.
We therefore at the central station make provision for coupling each wire
(through the call instrument with which it is connected) to a separate earth and
also at the opposite or outer end of the cable, where the several wires are led away
to various offices or stations; we couple the several wires through instruments to
separate and independent earth plates which have no metallic connection one with
the other.
In addition to making provision for coupling each wire to a separate earth at
the central and outlying stations, we also arrange the commutator or coupling
board at the central station, in such a manner that when any one wire is coupled
to any other wire they may also be coupled to an independent earth plate
preferably through a resistance coil,
If at the central station a separate earth connection cannot be obtained we
plant an earth plate of considerable area and then convey our earth wires to this

page_text: plate, and in such manner that there can be no escape or communication between
the several different wires until they are actually brought together by means of
the earth plate under ground.
The Drawings annexed show how our Invention may be carried out when one
form of commutator or coupling board is used. This form of commutator or
coupling board is similar to those commonly used at the central stations of systems
of electrical communication. The only alternation that is required is that a
separate earth is provided for each wire coming to it instead of having one common
earth connection as heretefore.
Figure 1 is a diagram plan view of the key-board, in which the lines A marked
1 to 50 represent metallic strips coupled to 50 different wires leading to 50 different
distant stations.
The thin lines B at right angles to these lines represent strips of metal to which
any of the wires 1 to 50 can be coupled up by the insertion of a metallic key or
plug x between them, as shown at Figure 5, one such plug X is provided for each
bar A. These numerous parallel bars or strips B of metal are for convenience
divided into series A, B, C, &c. The bars in one or more of the series are used for
coupling together such of the wires 1 to 50 as it may at any one time be required to
couple together whilst the bars of the other series are by wires put in electrical
communication with corresponding bars on other commutators or coupling boards,
as is well understood.
Parallel with the cross bars B are, in the ordinary form of commutator or
coupling board, three other bars, one marked C coupled to earth, another D to one
wire from a battery, and another E to one wire of a telephone, so that by shifting
the position of the keys X the bars A can be set to earth, or coupled to one wire of
a battery, or to a telephone at the central station, or can be coupled to any of the
bars or strips B, as before stated. In place however of the earth bar C being in
one piece and-connected by one connection to earth as heretofore, we (as represented
by the diagram, Figures 2 and 3) divide it into as many parts as there are bars A
in the commutator or coupling board, and connect each part by a separate insulated
wire to a separate earth plate. The insulated wires leading to earth may, as shown
at Figures 2 and 3, be cabled together and led away to any desired distance before
being put to earth.
In Figure 3, F, F, are cables of wires coming from outlying stations; G are
means for protecting the instruments from injury by lightning; H are electro
magnet call instrument apparatus; I, wires from such apparatus to one or other of
the bars A of the commutator or coupling board, Figure 1; C, C, are the separate
earth connections by which any one or other of the bars A can be put to earth;
K, K, are the separate and independent earth plates, one for each bar A.
In cases
where at the central station separate and independent earth plates cannot be
provided for each wire, then the several insulated wires leading to earth may all
be coupled to one metallic earth of large dimensions, as shown at Figure 7.
A plan view of a part of the bars A and B is shown at Figure 4, and a cross
section in Figure 5; in this latter Figure a plug X is also shown, coupling one
bar A to a bar B. Á side elevation of one of the plugs is shown at Figure 6;
Figure 8 is a perspective view showing parts of the apparatus.
When it is desired that any two wires when coupled together at the central
station by being coupled to one or other of the bars B shall also be coupled to
earth; this is readily effected by connecting each of the bars B of the key board
by separate insulated wires to separate and independent earth plates; preferably
this connection to earth is made through resistance coils.
We claim,-
First. In systems of electrical communication where numerous stations åre
connected by wires with a central station, the employment of a separate and
independent earth plate, or separate connection with a large earth plate for each
of the wires which are led into such station, and which are either cabled together
or carried along for a distance in proximity to one another.

page_text: Second. In systems of electrical communication where numerous distant stations
are connected with a central station by wires bunched or cabled together, the
employment at such distant stations of a separate and independent earth plate for
each wire.
Third. The construction of commutators or coupling boards used at such central
stations in such a manner that each wire of a bunch or cable of insulated wires
may be coupled to an independent earth plate, or separately connected to a large
earth plate.
Fourth. The construction of commutators or coupling boards used at such central
stations in such a manner that when any two of the wires from distant stations
have been coupled together they may at the same time be coupled to an independent
earth.
In witness whereof, I, the said James Wallace Brown, have hereunto set my
hand and seal, this Thirtieth day of May, in the year of our Lord One
thousand eight hundred and eighty-one.