IMPROVEMENTS IN TELEGRAPHY AND TELEPHONY
Year: 1885

page_text: I, CHARLES LANGDON-DAVIES of 110 Cannon Street in the City of London,
Electrician do hereby declare the nature of my invention for "IMPROVEMENTS IN
TELEGRAPHY AND TELEPHONY to be as follows:-
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This invention has for its object improvements in telegraphy and telephony.
It has before been proposed to employ ordinary telegraphic line wires for the
purpose of simultaneous communication by means of telephones and also by means
of harmonic telegraph instruments and numerous experiments have been made
with this object in view. But the telegraphic currents are found greatly to
interfere with the use of the telephone, producing sound in the receiving telephone
and drowning the voice of the speaker at the transmitting telephone. Similar
disturbances occur when harmonic instruments are employed.
It has been attempted to remove or diminish this difficulty by modifications in
or in connection with the transmitting key of the telegraph. The object of these
modifications has been to render less sudden the shocks resulting from, making
and breaking contact by the telegraph key. To this end condensers have been
connected with the key and a certain amount of success is obtained by the use of
condensers in this way so long as the condensers remain intact and in proper
working order. But condensers so applied are very liable to injury by electric
storms or even by earth currents of more than ordinary intensity. In the use of
condensers in this manner it is found after a short time that the diaelectric of the
condenser has become perforated and the condenser is then useless for the purpose
for which it is applied.
Now according to my invention I employ in this manner and for this purpose in
place of condeusers an instrument which I term a phonopore and which consists
essentially of two insulated wires laid side by side and together wound upon a reel
or made into a bundle in any convenient manner. One of these wires is placed in
electrical communication with the transmitting key and the other is connected to
earth, but by neither wire is the circuit completed. Such an arrangement when
the wires are suitably insulated and arranged yields greater advantages than has
heretofore been obtained by the use of condensers and the instrument is not liable
to injury by electric storms or earth currents.
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page_text: Improvements in Telegraphy and Telephony.
I CHARLES LANGDON DAVIES of 110 Cannon Street in the City of London
Electrician 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 :-
This Invention has for its object improvements in telegraphy and telephony.
It has before been proposed to employ ordinary telegraphic line wires for the
purpose of simultaneous communication by means of telephones and also by means
of harmonic telegraph instruments and numerous experiments have been made
with this object in view. But the telegraphic currents are found greatly to
'interfere with the use of the telephone, producing sound in the receiving telephone,
and drowning the voice of the speaker at the transmitting telephone. Similar
disturbances occur when harmonic instruments are employed.
It has been attempted to remove or diminish this difficulty by modifications in,
or in connection with the transmitting key of the telegraph. The object of these
modifications has been to render less sudden the shocks resulting from making and
breaking contact by the telegraph key. To this end condensers have been con-
nected with the key, and a certain amount of sucess is obtained by the use of
'condensers in this way, so long as the condensers remain intact and in proper
working order. But condensers so applied are very liable to injury by electric
storms or even by earth currents of more than ordinary intensity. In the use of
'condensers in this manner it is found after a short time that the di-electric of the
condenser has become perforated and the condenser is then useless for the purpose
for which it is applied.
Now according to my invention I employ in this manner, and for this purpose in
place of condensers an instrument which I term a phonopore, and which consists
essentially of two insulated wires, laid side by side, and together wound upon
a reel or made into a bundle in any convenient manner. One of these wires is
placed in electrical communication with the transmitting key, and the other is
connected to earth, but by neither wire is the circuit completed. Such an arrange-
'ment when the wires are suitably insulated and arranged yields greater advantages
than has heretofore been obtained by the use of condensers and the instrument is
not liable to injury by electric storais or earth currents.
!
In order that my said invention may be most fully understood and readily
carried into effect I will proceed to describe the drawing hereunto annexed"
DESCRIPTION OF THE DRAWING.
The drawing represents in a diagrammatic form, the arrangements which I make
when using the same line wire for telegraphic communication and simultaneously
for comunication by means of telephones or by means of harmonic instruments.
a is the line wire serving the double purpose as stated above, it is shown in
connection at one end, with an ordinary telegraph station and also with a telephonic
or harmonic station.

page_text: There may be similar stations at the two ends of the wire. b is the telephonic
or harmonic station, with its earth connection b'. The arrangements in this station
may be of any ordinary and convenient description and the connection is made by
means of a phonopore as is described in the Specification of a former Patent
granted to me No 10990 in the year 1884.
The ordinary telegraphic station is provided with the battery d key receiving
instrument and earth connections g also arranged in any usual and convenient
manner.
The phonopore h is applied in such manner as to lessen the suddenness of the
shocks resulting from the use of the finger key e so that the use of the finger key
may not interfere with the telephonic harmonic or like instruments in the station b.
i is an electro magnet which I prefer to include in the circuit as has before some-
times been done. The phonopore / consists of two or more coils of wire in close
proximity-one of these coils may serve as the connection between the station and
the line wire; another is insulated at one end and connected permanently to earth
at the other end whilst a third coil (if such be employed as is preferred) forms
a closed circuit.
A phonopore suitable for this purpose is composed of two strands of N° 30
B. W. G wire separately covered with silk and then laid side by side and recovered.
More than two wires may be employed and arranged in the same way.
Of such a compound wire or strand 400 yards are wound on a wooden bobbin
and the ends are brought out. The length stated above will usually be found
sufficient but this will depend to some extent on the length of the line wire
and on the battery power employed..
If the length of compound wire in the phonopore be found insufficient in any
case the employment of a greater length will overcome the difficulty.
Sometimes in place of connecting the line wire with the station directly it may
be connected by means of another phonopore as described in the Specification of a
Patent granted to me No 10990 in the year 1884.
The phonopore h, may advantageously contain a third wire and in this case the
two ends of this wire are connected and form a closed circuit.
The phonopore h may be connected any where between the key contact and the
branch by which the' telephone or harmonic station communicates with the line
wire, but the position indicated in the diagram is preferred.
The phonopora when employed in accordance with this invention in simultaneous
telegraphy is much more efficient than a condenser similarly employed; it also is
not liable to injury by earth currents, and it is less expensive..
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is:-
The use substantially as described in simultaneous telegraphy of a phonopore in
such manner as to moderate the shocks resulting from the opening and closing of
the telegraph circuit by the key, 80, that such shocks may not interfere with the
reception of telephonic messages or harmonic signals transmitted on the same
line wire.
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