Improvements relating to Simultaneous Telephony and Telegraphy.
Year: 1891

page_text: Date of Application, 19th Dec., 1891
Complete Specification Left, 18th Oct., 1892-Accepted, 19th Nov., 1892
PROVISIONAL SPECIFICATION.
Improvements relating to Simultaneous Telephony and Telegraphy.
We, JOHNSTON STEPHEN, of 1 Montague Street, Russell Square, Electrician,
and CHARLES DAVIS, of 147 New Bond Street, Gentleman, both in the
County of Middlesex, do hereby declare the nature of this invention to be as
follows:-
Our invention relates to simultaneous telephony and telegraphy.
The object of our invention is to enable telephonic communication to be carried
on by means of a circuit through which at the same time a telegraphic message is
being transmitted.
Attempts have been made at various times to attain this very desirable result
by putting a telephone receiver and transmitter in circuit with an ordinary Morse
key and sounder or an ordinary reversing tapper key or the like but whenever this
has been done a confused noise was heard in the receiver when the key was worked
and the circuit made and broken, rendering the transmission of audible speech an
impossibility. Several modes of obviating these noises have been proposed, but
they have been either unsuccessful or the expense attending the same has been
practically prohibitive of their use.
We have found that the noises in the telephone receiver depend on the
fact that the telegraphic signal current is actually broken each time the key is
operated.
Now according to our invention we do not break the circuit but we so arrange
that it shall only be varied within comparatively narrow limits by the operations
of the key, and we then find that we are enabled to transmit telephonic communica-
tions simultaneously with the telegraphic communications.
In carrying our invention into practice we arrange that the operator shall
transmit telegraphic signals by merely increasing or diminishing the resistance of
the circuit thus decreasing or increasing the current, instead of by making and
breaking the circuit, or by reversing the current in the same.
We can do this for example by constructing a Morse key of special form which
shall not make and break the circuit when operated, but which shall increase or
diminish the current in the same within suitable limits, by increasing or diminishing
the pressure on a series of small carbon plates or lamine. The said series of carbon
plates are included in the circuit and form a considerable part of its resistance,
hence when the pressure is increased the current in the circuit increases and when
the pressure is diminished the current also diminishes. We find when using such
apparatus for transmitting telegraphic signals, that if a telephone receiver and
transmitter be included in the circuit, audible telephonic signals may be sent
through the wires simultaneously with the telegraphic messages, thus practically
doubling the usefulness of the wires.
It is obvious that we can modify any telegraph transmitter in the manner herein-
before indicated, and use it with any type of telephone transmitter and receiver
included in the telegraph circuit in any suitable manner without departing from the
nature of our invention. Also that instead of using the carbon discs we may
employ any other suitable device for varying the resistance for the purpose of our
present invention.

page_text: COMPLETE SPECIFICATION.
Improvements relating to Simultaneous Telephony and Telegraphy.
We, JOHNSTON STEPHEN, of 1 Montague Street, Russell Square, Electrician,
and CHARLES DAVIS, of 147 New Bond Street, Gentleman, both in. the County,
of Middlesex, 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 :-
Our invention relates to simultaneous telephony and telegraphy.
The object of our invention is to enable telephonic communication to be carried
on by means of a circuit through which at the same time a telegraphic message is
being transmitted.
Attempts have been made at various times to attain this very desirable result, by
putting a telephone receiver and transmitter in circuit with an ordinary Morse key
and sounder or an ordinary reversing tapper key or the like but whenever this has
been done a confused noise was heard in the receiver when the key was worked
and the circuit made and broken, rendering the transmission of audible speech an
impossibility. Several modes of obviating these noises have been proposed, but
they have been either unsuccessful or the expense attending the same has been
practically prohibitive of their use.
We have found that the noises in the telephone receiver depend on, the
fact that the telegraphic signal current is actually broken each time the key is
operated.
Now according to our invention we do not break the circuit but we so arrange
that it shall only be varied within comparatively narrow limits, by the operations
of the key, and we then find that we are enabled to transmit telephonic communica-
tions simultaneously with the telegraphic communications.
In carrying our invention into practice we arrange that the operator shall
transmit telegraphic signals by merely increasing or diminishing the resistance of the
circuit thus decreasing or increasing the current instead of by making and breaking
the circuit or by reversing the current in the same.
In the accompanying drawings,
Figure 1 is a side elevation of a Morse key adapted for use in a telegraph circuit
and constructed according to our invention.
Figure 2 is a detail sectional view of part of the key shewn in, Figure 1.
Figures 3 and 4 are detail views illustrating modified forms of parts of the Morse
key shewn in Figure 1.
Like letters of reference denote similar parts in all the drawings.
A is the bar of the key pivoted at A¹ to the supports B which are secured to
the base board B. C is the lower back contact of the key secured to the base
board and C¹ is the corresponding upper contact secured to the bar A. D are a
number of discs or lamina which are included in the space between the upper and
lower contacts D', D2 of the key. These discs or laminæ are made of carbon or
other semi-conducting material of suitable size and thickness and are preferably
of a lenticular shape in cross section as shewn in Figure 2. The pile, of discs
generally possesses a certain amount of spring or elasticity owing to their shape and
the material of which they are composed. E is a spring which tends to keep, the
key bar in the position shewn in Figure 1, as is usual in Morse keys.
A key constructed in the manner above described does not make and break the
circuit when operated but only varies the resistance in a greater or less degree
according to the number of carbon discs and the range of motion of the front part
of the key bar.
To obtain a greater range of motion of the key bar and,so retain the coarseness
and freedom of movement associated with the ordinary Morse key and to permit of
the key coming home upon a dummy" front contact we sometimes insert an
66

page_text: adjustable spring between the key and the carbon discs as shewn in Figures 3 and 4,
where D' is a metallic spring which electrically connects the uppermost carbon
disc to the key bar. The spring can obviously be arranged at the bottom instead
of or as well as at the top if desired.
We have herein described our invention as applied to a Morse signalling key
but it must be understood that carbons or semi-conducting discs or laminæ may
be used in a similar manner with other forms of key which are used to open
and close a circuit such as for instance with an ordinary single contact key.
We find when using such apparatus for transmitting telegraphic signals, that if
a telephone receiver and transmitter be included in the circuit audible telephonic
signals may be sent through the wires simultaneously with the telegraphic messages,
thus practically doubling the usefulness of the wires.
This effect is obtained whether the telephones be directly included that is in
series with the line or whether they be included in a secondary circuit, as we prefer
to arrange them. Our invention is also applicable to complete metallic circuit
telegraphy as well as to ordinary single line telegraphy.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
:-
1. A key for use in telegraph circuits having a series of discs or laminæ made
of semi-conducting material between its contacts, substantially as described for the
purpose specified.
2. A Morse signalling key constructed with a series of carbon discs of lenticular
section placed between its contacts, with or without a spring, substantially as
described with reference to the accompanying drawings, for the purpose specified.
Dated this 18th day of October 1892.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicants.