IMPROVEMENTS IN CIRCUITS FOR TELEPHONIC COMMUNICATION
Year: 1882

page_text: LETTERS PATENT to Henry Alabaster, of South Croydon, in the County of
Surrey, and Tom Ernest Gatehouse, of Camberwell, in the County of
Surrey, both Electricians for an Invention of IMPROVEMENTS IN CIRCUITS
FOR TELEPHONIC COMMUNICATION
PROVISIONAL SPECIFICATION left by the said Henry Alabaster and Tom
14
Ernest Gatehouse at the Office of the Commissioners of Patents on the
30th October 1882.
HENRY ALABASTER, of South Croydon, in the County of Surrey, and Tox
ERNEST GATEHOUSE, of Camberwell, in the County of Surrey, both Electricians
IMPROVEMENTS IN CIRCUITS FOR TELEPHONIC COMMUNICATION
"
Our invention relates to the arrangement of circuits for telephonic communication
where an induction coil and induced currents are used, and is designed to improve
the clearness and loudness of articulated messages or other sounds.
It is usual, where an induction coil and an induced current are used, to place the
telephone receiver in the secondary or induced circuit forming part of the line
wire.
We find that greatly improved results in clearness and loudness can be obtained
by placing the telephone receiver in a local circuit, which usually includes the
transmitter and a suitable battery and which forms the primary wire of the
induction coil. The secondary wire thus forms part of the line wire without direct
communication with either transmitter or telephone receiver, and is put to earth at
each end.
A constant local primary current at each station thus passes through the receiver
as through the transmitter.
In the transmission of words or sounds from one station to another, the current,
induced by the variations of the primary transmitting current, does not act directly
on the receiver at the other station, but by induction produces the necessary
variations in the constant local current passing through the receiver at the receiving
station.

page_text: Alternatively we may employ for the receiver an independent tertiary circuit,
(with a battery) wound round the induction coil so as to receive the necessary
induced variations from the secondary line wire, and including a suitable battery.
Where a telephone receiver with a permanent magnet is used the battery in the
tertiary circuit may be dispensed with.
Where an annealed iron core in the telephone receiver requires an active current
to induce magnetism, the batteries in the primary and tertiary circuits, herein before
described, provide this. Alternatively in the case of the tertiary induced circuit,
the battery, described in relation thereto may be arranged in an independent closed
circuit connected direct with the telephone receiver.
In the application of our improved telephonic receiver (patented to us in con-
junction with Harry Robert Kempe under date June 7th 1882, and numbered 2675)
to this improved arrangement of circuit, the presence of a battery in the samo
primary or tertiary circuit with our receiver, dispenses with the double wire in the
said receiver, one only being necessary.
Should it however be advisable to use two coils in the said receiver, the secondary
wire of the induction coil is placed in connection with the second coil of the
receiver before going to earth.
.
Our above described improvements in circuit arrangement are however applicable
to any telephonic receiver whether working with permanent or electro magnets

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Henry Alabastor and Tom Ernest Gatehouse in the Great Seal Patent
Office on the 30th April 1883.
HENRY ALABASTER, of South Croydon, in the County of Surrey, and Toxt
ERNEST GATEHOUSE, of Camberwell, in the County of Surrey, both Electricians,
JMPROVEMENTS IN CIRCUITS FOR TELEPHONIC COMMUNICATION
"
Our invention relates to the arrangement of circuits for telephonic communication
where an induction coil and induced currents are used, and it is designed to
improve the clearness and loudness of articulated messages or other sounds.
It is usual where an induction coil and an induced current are used, to place the
telephone receiver in the secondary or induced circuit forming part of the line
wire.
We find that greatly improved results in cloarness and loudness can be obtained
by placing the telephonic receiver in a local circuit, which usually includes the
transmitter and a suitable battery, and which forms the primary wire of the
induction coil. The secondary wire thus forms part of the line wire, without direct
communication with either transmitter or telephone receiver, and is put to earth at
each end.
This arrangement is illustrated at Figure 1 on the drawings appended hereto,
where A and B are the two stations, connected by the line wire C. Suitable
continuations of this line wire are wound as secondary wires upon the induction
coils D and D', and the extremities are put to earth at E and E' respectively.
The receiver R. and transmitter T with a battery F at each station, are placed
in a local circuit, forming the primary wire of the induction coils.
In the transmission then of words or sounds from one station A to the station B,
the current induced in the line wire by the variations of the primary transmitting
current does not act directly on the receiver at the other station B, but by
induction produces the necessary variations in the constant local current passing
through the receiver at the receiving station B
The term circuit used herein may be understood to mean a circuit metallically
closed, or an open circuit, so long as the approximation of the terminals, or other
conditions, permits an electrical impulse to travel through or along tho said circuit
By special construction an instrument may, if desired, be used in conjunction
with a battery in the local primary circuit herein before described, which shall act
both as a transmitter and as a receiver.
Alternatively, we may employ for the receiver an independent tertiary circuit,
wound round the induction coil, so as to receive the necessary induced variations
from the secondary line wire. This circuit includes a suitable battery, where the
receiver is not provided with a permanently magnetised core, in which latter case
the battery in the tertiary circuit may be dispensed with.
These arrangements of tertiary circuit are shown at Figures 2 and 3. In tho
former the receivers R are in independent circuits, each including a battery Fat
each station, the wire being wound as a tertiary layer on the induction coils D D¹
Suitable continuations of the line wire form the secondary coil in both induction
coils, the extremities being put to earth at E and E'.
The transmitter T is placed in a primary local circuit including a battery F¹.
Figure 3 shows a receiver such as the "Dolbear" in the tertiary circuit, which,
in such case, is an open circuit, which may or may not include a battery. A great
advantage results from our arrangement of an independent tertiary circuit, where
a current of high tension (intensity) is required for the receiving instrument such
for instance as the "Dolbear."

page_text: Any required tension (intensity) of the current, may be obtained in the small
tertiary circuit, without requiring the same in the line wire, which would cause
excessive leakage.
Similarly, the current in the tertiary circuit may be a so-called "quantity" current
of low tension (intensity), to suit the receiver, which would not be feasible in & line
wire of considerable length and consequently of high resistance.
Alternatively a condenser-transmitter T may be placed in the primary circuit
together with a battery F as in Figure 4, the circuit in this case being an open
one; Any convenient receiver R is placed in the tertiary circuit as before with a
battery F.
Again, in the case of the tertiary induced circuit, the battery described in relation
thereto may be arranged in an independent closed circuit F, connected direct with
the telephonic receiver, as shown in Figure 5.
In the application of our improved telephonic receiver (patented to us in
conjunction with Harry Robert Kempe under date June 7th 1882 and numbered
2675) to this improved arrangement of circuit, the presence of a battery in the
same primary or tertiary circuit with our receiver dispenses with the double wire
in the said receiver, one only being necessary.
Should it however be advisable to use two coils in the said receiver, the secondary
wire of the induction coil is placed in connection with the second coil of the receiver,
before going to earth.
'
Our above described improvements in circuit arrangements are however
applicable to any suitable telephonic receiver, and all connections to earth may
be read as connections by a return wire.
Having now described and ascertained the nature of our invention, and the
manner of carrying the same into effect, be it known that what we consider novel
and desire to protect by Letters Patent is :-
First. The combination of a line wire, which after forming by its continuations
the secondary wire of an induction coil at stations, is connected at each end to earth
-or a return-wire:;-with-a-primary-local-circuit, either open-or-metallically-closed,-in-
which any known receiver and transmitter, or an instrument capable of both
transmitting and receiving, together with a battery, is included; substantially as
and for the purposes described.
Second. The combination of a line wire whose continuations are wound at
stations as a secondary wire on an induction coil, and put to earth or a return wire
at each end; with a primary local circuit either open or inetallically closed,
including a battery and a transmitter; and further with a tertiary circuit either
open or metallically closed containing any known receiver, with or without a
battery as required, or with the battery in auxiliary circuit with the receiver,
substantially as and for the purposes described.
In witness whereof I the said Tom Ernest Gatehouse on behalf of myself
and the said Henry Alabaster have hereunto set my hand and seal this
twenty-fourth day of April in the year of our Lord One thousand eight
hundred and night then
Witness:-
JOHN. C. FELL
Patent Agent
23 Rood Lane, EC.
TOM ERNEST GATEHOUSE (L.S.)