An Improved System of Telegraphy and Telephony.
Year: 1891

page_text: Date of Application, 28th Apr., 1891
Complete Specification Left, 25th Jan., 1892--Accepted, 27th Feb., 1892
PROVISIONAL SPECIFICATION.
An Improved System of Telegraphy and Telephony.
ALFRED ROSLING BENNETT, Electrical Engineer, 22, St. Alban's Road,
Harlesden, London, N.W. do hereby declare the nature of this invention to be as
follows:-
The object of my invention is to enable telephonic conductors when arranged in
metallic circuits to be utilised also for telegraphy without reducing their telephonic
efficiency and to enable two telephonic conversations to be transmitted simul-
taneously by means of the same metallic circuit.
When two towns or other separated points are connected by an aerial telephonic
metallic circuit, I erect, from each end of the route, on the same poles and parallel
to the general course of the metallic circuit one or more single wires for a distance
which varies with the battery power employed, with the number of single wires
erected and with the distance which separates the single wire or wires from the
metallic circuit. When they have been. run out from the ends for a sufficient
distance supported on any efficient form of insulator these single wires may
terminate either with insulated ends or by being connected through an electro-
magnet or other resistance to the earth.
If the single wire or wires at one end of the metallic circuit are arranged so that
currents can be sent into them'at will from a battery or magneto machine one pole
of which is connected to the earth, and the single wire or wires at the other end
of the metallic circuit are connected through a telephone to the carth, the currents
from the battery or magneto machine will be heard in the telephone and telegraphic
signals can be transmitted from one single wire or set of single wires to the other.
The transmission is effected by means of electrostatic induction acting at the one
end between the single wire or wires and the metallic circuit and at the other end
between the metallic circuit and the single wire or wires. If telephones or
telegraphic instruments are joined in the metallic circuit their operation will not
be affected by this electrostatic transmission.
To render the signals distinctly audible in the telephone it is desirable to employ
at the sending end a vibrator or make-and-break which will either furnish rapid
reversals or rapid interruptions. In some cases it is desirable to employ a vibrator
which sounds a musical note or supplies interruptions of known frequency and to
furnish the telephone used as a receiver with an armature or diaphragm attuned to
the same musical note or to the same number of vibrations. The telephone will
then respond more freely to the signals intended for it than to inductive disturbances
from other wires.
Instead of apparatus for sending telegraphic signals a telephonic transmitter
may be fitted at the sending end. Telephonic conversation will then be transmitted
between the two single or sets of single wires without disturbing any telegraphing
or telephoning that may be proceeding on the metallic circuit.
More than one metallic circuit may be utilised between the same points. When
several single wires are employed they may be fitted at the sending end each with
a vibrator giving a different musical note or rate of interruption and at the receiving
end with telephones having armatures attuned each to its corresponding vibrator.
It will then be possible to transmit simultaneously as many telegraphic messages
as there are single wires all without disturbing the ordinary functions of the
metallic circuit.
The invention may be applied to insulated wires made up into bundles or cables
by laying single wires for the necessary distance parallel and close to the wires
composing the metallic circuit

page_text: Intermediate sections of single wire or wires may be erected along the course of
the metallic circuit. If such intermediate sections are fitted with vibrators and
telephones they will be in communication with the terminal stations and with each
other, each section influencing the others through the metallic circuit by electrostatic
induction.
5
COMPLETE SPECIFICATION.
An Improved System of Telegraphy and Telephony.
I, ALFRED ROSLING BENNETT of 22, St. Alban's Road, Harlesden, London,
N.W., Electrical 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 :-
My invention relates to the utilisation of metallic circuits for the transmission of
telegraphic or telephonic messages in addition to and without disturbing the
ordinary functions of the metallic circuits.
My invention may be carried out and given effect to practically in the following
manner. When one or more metallic circuits consisting of bare wires supported
on insulators or of covered wires whether supported on insulators or not exist
between two points or stations, well-insulated single wires of any suitable metal
may be erected on the same supports, starting from each station and strung parallel
to the wires or conductors composing the metallic circuits at eight, ten, twelve or
any convenient number of inches from them. One single wire may be erected
from each end, or any convenient number. If several single wires are erected they
need not be run out so far from the stations as if one only were employed since
the working of my invention depends chiefly on two circumstances, namely, the
amount of surface presented to the metallic circuits by the single wire or wires
and the distance between them. For these reasons the single wire or wires may
advantageously be of the largest convenient gauge and be strung as closely to the
inetallic circuits as mechanical considerations will allow. The nearer the single
wire or wires are to the metallic circuits and the greater the surface presented by
the single wire or wires the smaller will be the voltaic or other power required to
work the instruments connected to the single wires. If the stations are fifty miles
apart it will suffice to run out one single No. 11 wire for six miles from each end,
or two such wires for three miles or three such wires for one mile. When the
metallic circuits are longer than fifty miles the single wires may be lengthened
in the same proportion. The single wire or wires may either terminate abruptly
with their distant ends insulated or their distant ends may be connected to earth
through an electro-magnet or other resistance or be attached to one plate of a
condenser the other plate of which is earthed. If the distant ends are connected
to earth through an electro-magnet or other resistance, the resistance employed
may be one thousand ohms.
At the station end the single wire or wires are connected through the signalling
apparatus to earth. When cables or bundles of insulated wires are employed for
the metallic circuits the single wire or wires should be laid up amongst them. The
distance between the single wires and the metallic circuits being much less in this
case the length of the single wires may be greatly reduced, one mile at each end
being sufficient if only one single wire is employed. With cables or bundles of
wires the single wire or wires may be replaced by a metallic sheathing surrounding
individual wires of the cable or the entire cable provided the sheathing can be
kept insulated from the earth and otherwise dealt with and connected in the manner
herein described as necessary for the single wires. The surface available for
inductive action between the single wire or wires and the metallic circuits may be
augmented to any desired extent by including in the circuits of both the metallic

page_text: circuits and the single wire or wires lengths of cable containing all the necessary
conductors, which cable may be wholly or in part within the station buildings.
The whole of the necessary inductive effect between the single wire or wires and
the metallic circuits may be brought about by cable coiled or otherwise disposed
within the station buildings if the running of outside wires is impracticable but
this plan involves the addition of otherwise useless and probably prejudicial length
to the metallic circuits.
The telegraphic apparatus to which the single wire or wires are connected at the
stations may consist essentially of three parts, firstly, a source of electricity which
furnishes intermittent or alternating currents of high frequency, such as may be
obtained from a magneto or dynamo machine of suitable construction or from a
voltaic battery or thermo-pile by the agency of an interruptor, vibrator or pole-
changer; secondly, a transmitter, which may be an ordinary Morse key; and
thirdly, a receiver, which may be simply an ordinary bell telephone used as a
sounder, although a telephone in which the distance between the magnets and the
diaphragm can be varied at will by means of a micrometer screw would be preferable
since it could be adjusted to exclude inductive disturbances from other sources or
wires. The effect of such disturbances may also be reduced by using a sending
vibratory current of musical or well defined frequency and attuning the diaphragm
or armature of the receiving electro-magnet to correspond. A sensitive relay
actuating an ordinary Morse sounder may also be employed as a receiver. Other
types of telegraphic apparatus may be used and I do not confine myself to any
particular pattern or combination since my invention is essentially for the method
of effecting the necessary induction between the single wires and the metallic
circuits and not for the signalling instruments.
The transmission of signals between the sets of single wires is brought about by
electrostatic induction, the combination forming practically a three plate condenser
the two earthed plates of which are constituted by the single wires and the middle
insulated plate by the metallic circuit or circuits.
My invention will only allow of one telegraphic circuit being worked between
two stations however numerous the metallic circuits may be between them unless -
the sending currents differ in character and the receiving instruments are so con-
structed that each will respond only to the current intended for it. This may be
effected by running out several single wires from each station and connecting them
to earth through separate signalling instruments, the sending parts of which
transmit vibrations of well-defined musical frequencies, each transmitter Fielding a
different note. If the receivers consist of telephones or other electro-magnets
having diaphragms or armatures attuned to correspond to the notes sounded by the
transmitters each receiver will respond only to its own transmitter and as many
messages as there are different notes may be simultaneously passed between the
two stations without interfering with the functions of the metallic circuit or circuits
which convey the inductive effects between the terminal single wires.
In lieu of telegraphic signalling, telephonic communication may be carried on
between the terminal single wires if suitable telephonic apparatus is substituted for
the telegraphic.
Intermediate sections of single wire or wires may be erected along the course of
the metallic circuit or circuits. If such sections are connected to earth through
suitable instruments such as are hereinbefore indicated they will constitute inter-
mediate induced telegraphic or telephonic stations which may communicate with
each other and with the two terminal induced stations without disturbing the
metallic circuit or circuits in any way. It is not necessary that both or either of
the induced stations should be at the ends of the metallic circuit route. On such
a route fifty miles long one induced station may be at one end and the other ten,
twenty or thirty miles distant. Or there may be one induced station at ten miles
from one end and another ten miles or any desired distance from the other.
Although in describing my invention I have used the word "wire" throughout it
must be understood that conductors in the form of strips, plates or tubes may be

page_text: employed for both the metallic circuits and the single lines and that when the
static capacity of the metallic circuits is not required to be kept low the working
of my invention may be facilitated by forming the conductors at least partly of
strips, plates or tubes since the opposing inductive surfaces can thereby be greatly
increased.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
'
1. Substantially in the manner set forth the utilisation of insulated conductors
forming metallic circuits, without interfering with their ordinary functions, for the
transmission of telegraphic signals between two or more sets of single conductors
run parallel and in proximity to the metallic circuits and insulated therefrom, the
said single conductors being joined to earth at one of their extremities through any
suitable telegraphic apparatus.
2. Substantially in the manner set forth the utilisation of insulated conductors
forming metallic circuits, without interfering with their ordinary functions, for the
transmission of telephonic speech between two or more sets of single conductors
run parallel and in proximity to the metallic circuits and insulated therefrom, the
said single conductors being joined to earth at one of their extremities through
any suitable telephonic apparatus.
3. Substantially in the manner set forth the effecting of the aforesaid purposes
by means of insulated conductors forming metallic circuits surrounded individually
or collectively by metallic sheathing which is connected to earth at one of its
extremities through suitable telegraphic or telephonic apparatus.
4. Substantially in the manner set forth the effecting of the aforesaid purposes
by means of cable containing the necessary conductors coiled or otherwise disposed
wholly or in part within the station buildings.
5. Substantially in the manner set forth the transmission simultaneously of more
than one telegraphic message over the same metallic circuit or group of metallic
circuits.
Dated this Twenty-third day of January 1892.