An Improved Telephone System.
Year: 1895

page_text: Date of Application, 12th Feb., 1895
Complete Specification Left, 7th Nov., 1895-Accepted, 18th Jan., 1896
PROVISIONAL SPECIFICATION.
[Communicated from abroad by CHRISTOPHER A. SHEA, of Milton, in the
County of Norfolk, Telegraph Operator, and FREEBORN FAIRFIELD
RAYMOND, 2d. of Newton, in the County of Middlesex, Lawyer, both in the
State of Massachusetts, United States of America.]
An Improved Telephone System.
I, HENRY HARRIS LAKE, of the Firm of Haseltine Lake & Co., Patent
Agents, 45 Southampton Buildings in the County of Middlesex, do hereby
declare the nature of this invention to be as follows:-
This invention has for its object the use of one wire grounded at each end and
used for telephonic purposes.
In order that the telephones will remain unaffected by induction from neigh-
bouring lines and earth disturbances and the like, there is wound around the cores
of the telephones a second wire, in the opposite direction to the first wire, and
grounded at both ends, similar in all respects to the first wire. The disturbances
are thus neutralized. The second wire is not for talking purposes, merely there to
balance inductive effects. The advantage of this arrangement is that smaller
copper wire or iron wire can be used for long distances, the currents meeting but
half the resistance and retardation and consequently being twice as strong.
Therefore in a metallic circuit five hundred or a thousand miles long where
large wires are used, the same distinctness and loudness can be obtained on a
smaller wire.
But one of the wires is spoken over, with earth return; the other is not spoken
over and lies dead, except in respect to balancing disturbing currents.
Now, while one dead wire, as we will call it, is balancing one live wire in point
of inductive disturbances, can at the same time balance another live wire in two
separate and distinct telephones, said third wire being entirely associated with the
first wire.
In this way it can be carried out still further and made to balance a fourth, and
Eo on.
So, while but one wire is used for one talking circuit with earth return, and
another grounded wire used for another talking circuit, and another one used for a
third talking circuit, each one will be as perfectly quiet as a metallic circuit,
because the common to all balancing wire neutralizes in each telephone all inductive
disturbances, thus enabling two conversations to be carried on over three wires
where it now takes four, and three conversations to be carried on over four wires
where it now takes six, and so on.
1 will now describe my invention.
In the two-wire system, one wire is carried around a telephone core in one
direction and grounded, this we will call the live wire, the connection on the other
end being the same, and speech is exchanged over it. This would be a very noisy
circuit but for the silencing effect from another wire run parallel to it all the way,
and wound around the telephone core at each end in the opposite direction to the
live wire and grounded. The transmitters are placed in the live wire circuit.
In the three-line circuit we will, for illustration, call line 1, one talking line
connected at each end around a telephone in one direction and grounded. The
telephones in this line we will call T and T".

page_text: On line three (3) are two telephones T and Ts around which the line is con-
nected in a certain direction and grounded.
Lines 1 and 3 do not in any way touch each other and are entirely separate, and
are called live or talking wireɛ.
Line 2 is a central wire running parallel to 1 and 3 on poles and in cables or
elsewhere, and is first connected around T and T¹ in the opposite direction to line 1,
and thence led around T2 T3 in. the opposite direction to line 3, thereby
neutralizing in each telephone all disturbing noises.
In all instances the lines can be connected around converters instead of
telephones.
=
An improved Telephone System.
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent
Agents, 45 Southampton Buildings, in the County of Middlesex, do hereby
declare the nature of this invention and in what mauner the same is to be
performed, to be particularly described and ascertained in and by the following
statement :-
"
The telephone service, so far as we are aware, was first intended, or at any rate
used for short lines, and one wire only. was employed, the circuit being completed
by earth connections. As the wires for electrical purposes increased in number
and the necessity for increasing the distance between telephone stations increased,
the single wire service began to suffer from the effects of induction currents from
neighbouring wires, from the atmosphere and from the earth, and it was finally
ascertained that it was desirable to cut off the earth connections and connect the
termini of the line by another wire, to form a continuous metallic circuit not
connected with the earth, and when such additional wire was run parallel with the
first, and close to it, it was discovered that induced currents of all kinds were
neutralized to such an extent that there was much less or no disturbance from
them produced in the telephones, and in practice it has been found that a continuous
metallic circuit of this kind does in effect practically silence all noise in the
telephone caused by inductive disturbance.
While the metallic circuit has this advantage, it is found to have a disadvantage
in that the distance over which its telephone currents travel is doubled by its use,
the telephone currents traversing the entire circuit created by the two lines instead
of a single wire as in the old system. This correspondingly decreases at the
receiving end the strength of the telephone currents, while it very much adds to
the expense of erecting, operating and maintaining the line, it being necessary to
provide wire, instrument, and other apparatus, of a capacity and power suitable
for a line just twice as long as the actual distance between two stations, and much
.more expensive than would be required if the service could be effected by a current
traversing one-half the distance, or over one line of the circuit or in one direction
only. Not only this, but if one side of the line only be used, the telephone current
.would be more effective for longer distances under known or commercial conditions.
I mean that with the same currents, instruments, and apparatus, now used between
.stations two hundred or five hundred miles apart it would be possible to obtain an
efficient service between stations twice that distance or four hundred or one thousand
miles apart, and without increasing the gauge of the wire. It is, however, possible
to use the metallic circuit for the purpose of preventing induction and at the same
°

page_text: time to employ but one of the wires or lines of the circuit for telephone or talking
purposes. This result we accomplish by connecting the metallic circuit with the
telephones or telephone converters at each end, substantially as hereinafter
specified, and connecting each telephone or telephone converter midway of the
winding of its coil with the earth.
The telephones or telephone converters_used vary from the ordinary telephone
or telephone converters in the winding. This is because the coil of the telephone
or telephone converter core is connected with the earth at the centre of its length,
and there must be upon each side of the earth connection the winding effect and
capacity of a telephone or telephone converter suitable for the service, in order
that a current coming from either line shall efficiently actuate the telephone.or
telephone converter in its passage over its section or part of the coil to earth. The
telephone or telephone converter thus wound and connected with the earth becomes
in effect a double telephone or telephone converter in that its core has two full
windings, either one of which when vitalized by the energizing current actuatės
the diaphragm, and each of which acts independently of the other, being
electrically separated from the other by an earth connection.
It will thus be seen that the system comprises two line wires, one a transmitting
line, and the other a neutralizing line. It is very essential for the successful
operation of the system, that these lines be balanced by each having the same
resistance. I provide means for accomplishing this, and I further provide
means for balancing the resistance of the neutralizing line with that of the
transmitting line, when the transmitting instrument is cut out of the line at
either end, which in practice is the case when the message is transmitted from
the other end.
In the diagram A and X are terniinal stations of the metallic circuit M.
TT are telephones or telephone converters at the respective ends of such
circuit. The coils C, C' respectively, of these telephones or telephone converters
are wound with twice the number of convolutions and have twice the resistance of
the ordinary telephone suitable for the service, and the coils of each are connected
at their middle with earth by the wires W W' and this forms a double telephone
or converter at each end of the line divided or separated electrically by an earth
connection. In other words, the telephone or converter thus constructed is
effectively operated by a current traversing either of the lines, the said current
going through the necessary number of actuating coils on the core of the telephone
or converter to earth.
and c represent the two sets of actuating coils of telephone T, and c¹ and c³
the two sets of actuating coils of telephone T.
It will be understood that whichever way the current enters the telephone or
telephone converter, and whichever of the coils is used the telephone or telephone
converter is constructed so that each set of coils has as great an effect as though
the other were not used; or, in other words, that the telephone or telephone
converter has two-actuating coils each taking its currents from a single line, each
operating only when receiving current from said line, and each having the power
and effectiveness of a full or complete telephone or converter; while at the same
time there is no disturbance in the telephone or converter from inductive currents.
D D' are the diaphragms of the telephones.
I are the induction coils with usual primary and secondary circuits.
B B' are keys for shunting the secondaries.
The telephones, induction coils and other apparatus can be loops from the central
exchange..
24
The action will be described in connection with the diagram. When A talks
to X the current starts from induction coil I, goes out on wire 2 of the metallic
circuit to station X, around the coil of telephone T', and the wire W' to earth
and back by earth to station A, and induction coil I. If for any reason it is
desired to switch the current leaving station A off the line 2 and on to the line 1
so that it goes out on wire 1 instead of wire 2 the current then actuates the
:

page_text: telephone T by traversing the coil c³, connecting with wire W to earth in the
same manner that it actuated the telephone when it traversed the other coil * from
wire 2 to the earth wire W'. With this system the balance of the line is more
easily thrown out or disturbed than with an ungrounded circuit, and when either,
for instance, of the secondary coils I or 1' is thrown on to the line 2, the line
would be unbalanced, unless it were correspondingly treated; and for this purpose
there are arranged to be connected with or thrown into circuit with line 1 the
balancing coils 12 12 which are connected with the line 1 by the same impulse
which throws either of the coils I or I¹ into circuit with the line 2, and there is
thus continued the balancing relation between the two line wires, as both are
simultaneously loaded and unloaded.
TR and T R represent the telephone transmitters.
m m' are loops in the line 2, and each has a circuit breaking key. These loops
shunt the secondaries when the circuits are completed by pressing down the keys,
and the line is so used while receiving a message, as it has been ascertained that it
is delivered more clearly to the receiving telephone if it is not passed through the
secondary coil, but about it. To cause the current to pass about the balancing
secondary coil of line 1, there is arranged in said line the loops m³, m³, and for each
of these loops there is a key which is mechanically connected with the key of the
corresponding loops of line 2 by an insulating piece m. The two keys so
connected are moved by a single impulse, so that, in use, the companion loops of
both lines are let on or off at the same time. When off, as in speaking, the current
passes through the secondary of line 2, and the secondary or line 1 being also on
"balances the secondary of line 2. When the secondary of line 2 is off, as in
receiving, the secondary of line 1 is off also and both lines are again simultaneously
brought into the same balanced relation.
From the above it will be seen that the telephone currents traverse but one wire
or side of the metallic circuit and meet with the resistance of only one wire or one-
half that of the circuit, whereas in the metallic systems now used the telephone
currents traversing both wires meet the resistance of the entire circuit which is at
least double that of one balf of the circuit or one wire. This practically shortens
the line by at least one-half, for the potential of the first half of the current upon
the line is higher than that of the second half.
The substantial benefit arising from this invention will be understood when it is
stated that with a telephone metallic circuit of say a. thousand miles in length
between stations, wires of larger gange and consequently greater cost, and more
delicate instruments, and consequently less reliable, are needed for installing and
.. working the system than in lines of half the distance; or, in other words, with one
.section or line of the telephone metallic circuit used as herein specified, wire of the
same gauge can be employed, and instruments of known efficiency used between
stations a thousand miles in length as now effectively employed between stations
upon complete metallic circuits of half that length. This makes a great saving in
the cost of the construction of long distance lines, and does not deteriorate the
service in any respect, but on the contrary gives a better service for the long extra
distance lines than could be otherwise obtained for such distances.
It will be understood, of course, that cross-talk is prevented by crossing the
-wires of the line and presenting reciprocally inductive sections to each other.
Figure 2 shows the same arrangement extended to three or more wires (two of
which are live or talking wires, and one of which is a dead wire) arranged in such
relation to each other that the single dead wire acts to balance the inductive
disturbances in both of the live or talking wires.
Referring to the diagram, T T¹ T T³ represent ordinary telephones.
11111 are induction coils with ordinary primary and secondary circuits.
1 is a live or talking wire connecting telephone T' with telephone T. 3 is a live
or talking wire connecting telephone T with telephone T³. Both of these wires at
their respective ends pass around their telephones and are grounded.
The wire 2 is a dead wire, and is connected with all the telephones T T T² Tª

page_text: by a winding, in the reverse direction to that of the winding of the live wire of the
said telephones; and is then grounded at each end.
The wires are strung in relation to each other to occupy an inductive relation to
each other and to any parallel disturbing wires, and the three wires are brought
into proper balanced relation with each other by the use of resistances where
needed; and I have represented in the diagram, the employment of resistances in
the lines 1, 2 and 3.-S' S² S³ S S and S being resistance coils, each of which is
composed of a number of coils of wire surrounding a permanent magnet. The
coil S is of the same resistance as the coil C of the telephone T. Coils S* S*
serve as a mean balance in the line 2 for the secondary coils. The spools: S³ S³ S°
serve the same purpose as the coil St.
It is to be understood that the wire 2 is dead at all times. It is used for
'the purpose of balancing the other two wires, and no currents whatever
'traverse it.
-
Assuming that T' is talking to T, the currents flow out on wire. 1. to
telephone and to earth, and no sound will be heard in T. or T³, because wires 2
and 3. maintain a balance in them. When T talks to T3 no disturbing -sounds will
be heard in Tor T2, wires 1 and 2 neutralizing all cross-talk. These three wires
are so disposed in relation to each other that each telephone has a balanced pair of
them which neutralize all inductive effects.
It will be understood, of course, that wire 3 does not touch telephones T¹ T.
.Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me
by my foreign correspondents, I-declare that what-I-claim-is-:-
1. The combination, in a telephone system, of the telephones or telephone.
converters, each having a winding connected at the centre of its length with earth,
the line 2 having the secondaries I l' and the loops m m³, about the secondaries,
the line 1 having the balancing coils 13, 13, the loops m², m³, and keys for simul-
taneously shunting and unshunting the loops, substantially as described.
2. The combination of two main lines, a receiving instrument at each end
included in both main lines, a transmitting instrument at each end connected with
one only of said main lines, meaus for cutting out of the line, at either end, the
transmitting instrument, and means for thereupon balancing the resistance of the
other line with the transmitting line, substantially as described.
3. The combination of two main lines, a receiving instrument at each end
included in both main lines, a transmitting instrument at each end connected with
one only of said main lines and, on the other line, a balancing device at each end
balancing the transmitting instrument at that end, substantially as described.
4. The combination of two main lines, a receiving instrument at each end
included in both main lines, a transmitting instrument at each end connected with
one only of said main lines, a balancing device at each end on the other line for
balancing the transmitting instrument, and means for cutting out of the lines at
either end, the transmitting instrument and balancing device, substantially as
described.
5. The circuit herein described for the transmission of electrical impulses,
comprising two wires presenting reciprocally inductive sections to each other, the
wires being connected at each end with the earth, and at one end being wound
around a receiving instrument, at the other end one wire having therein the
secondary coil of a telephone transmitter, and the other a coil similar to and
balancing said secondary, substantially as described.
6. The telephone system herein described comprising the two telephones at each
station, the live wires 1 and 3 connected with their respective telephones at the
stations and thence to earth, and the dead wire 2 connected with all of said
telephones and to earth, and inductively arranged in relation to the wires 1 and 3,
and meaus for balancing said wires to the same resistance, as and for the purposes
described.

page_text: 7. The combination of two live wires between two stations, each wire being
provided with means for transmitting and receiving an electrical impulse there-
along, said means including at each end a core and a coil of said wire around it,
with a third wire between said stations wound round said cores in succession in the
-opposite direction to the live coils round said cores, as and for the purposes
described.
8. The combination of the telephones or telephone converters T T¹ T' T³, the
wire 1 connecting the coils of telephones T¹ T' and passing from said coils to earth,
the wire 3 connecting coils of telephones T T³ and extending to earth, and the
wire 2 connected with coils upon the telephones T T' T' Ts and to earth, the coils
of the said telephones connected with wire 2 being wound reversely to those of the
actuating coils of said telephones, substantially as described.
-
9. The combination of the telephones or telephone converters T, T¹, T², T³, the
wire 1 connecting the coils of telephones T1, T2, and passing from said coils to
earth, the wire 3 connecting the coils of telephones T, Ts, and extending to earth,
and the wire 2 connected with coils upon the telephones T, T', T, Ts, and to earth,
the coils of which telephones connected with wire 2 being wound reversely to those
of the actuating coils of said telephones, and means for balancing said wires to
the same resistance, as and for the purposes described.
Dated this 7th day of November 1895.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.