IMPROVE- MENTS IN AND CONNECTED WITH TELEGRAPHIC AND TELEPHONIC SYSTEMS AND APPARATUS THEREFOR
Year: 1882

page_text: LETTERS PATENT to Philip Middleton Justice of 14 Southampton Buildings
in the County of Middlesex Patent Agent, for an invention of "IMPROVE-
MENTS IN AND CONNECTED WITH TELEGRAPHIC AND TELEPHONIC SYSTEMS
AND APPARATUS THEREFOR," A communication from abroad by Fr. Van
Rysselberghe of Schaerbeek. in the Kingdom of Belgium.
PROVISIONAL SPECIFICATION left by the said Philip Middleton Justice
at the Office of the Commissioners of Patents on the 17th March 1882.
PHILIP MIDDLETON JUSTICE of 14 Southampton Buildings in the County of
Middlesex Patent Agent
[
"
IMPROVEMENTS IN AND CONNECTED WITH TELEGRAPHIC AND TELEPHONIC SYSTEMS,
AND APPARATUS THEREFOR A communication from abroad by Fr.
Van Rysselberghe of Schaerbeek in the Kingdom of Belgium.
Where a network of wires exist which are employed for ordinary telegraphy, it
has hitherto been extremely difficult to practically employ one or more wires for
telephonic communication owing to the loss of current by induction, and also to
the currents induced from other lines The object of the present invention is to
remedy this defect and to enable one or more wires of a system to be employed for
telegraphy or for telephonic communication. This result may be attained by
modifying the present known systems and apparata and by applying known
instruments which have not hitherto been employed to secure the object indicated
For this purpose it is necessary to increase the intensity of the undulatory currents
of the microphone and induction coil and this is secured by employing an electric
source of extremely feeble interior resistance such as secondary batteries or
accumulators, and thermo electric piles These apparata have not to my knowledge
been hitherto applied for this purpose For the same purpose a number of hydro-
electric piles coupled in quantity may be used if the power does not exceed 4 volts
When several elements have heretofore been used for the microphone they have
been coupled in tension (en tension) According to my invention the surface of the

page_text: ordinary hydro electric element may be considerably enlarged in order to reduce
the interior resistance to a minimum The Leclanché cell has been used for both
telegraphy and for telephones and this form offers but little resistance If the
accumulator be adopted it could be maintained by a hydro electric pile of which
the power should be but little less than that of the accumulator when fully charged
As the current is used the accumulator is replenished from the pile. According to
my invention I employ microphones with multiple contacts and these must be
coupled in quantity (tous en quantité). Heretofore these have been arranged partly
in quantity and partly in tension
The Oder, Crossley, Gower-Bell, and other microphones as also the Blake and
other transmitters may be modified for multiple contacts in accordance with my
invention.
In the case of the Blake transmitter it is however necessary to have two or three
points of contact coupled in quantity It is found advantageous to cover the small
carbon cylinders of the microphone except at their points of contact with a metallic
coat to render them better conductors I also employ a commutator somewhat
similar to a Morse Key but which may be operated in any convenient manner and
whose mission is to put the receiver or the secondary wire of the induction coil out
of circuit as may be required; said commutator may also be arranged to alternately
open and close the circuit of the pile of the microphone
The
Heretofore each telephonic circuit has included the receiver the secondary circuit
of the induction coil and the communication wire at both ends of the line
construction of the coils in the telephone receivers I also modify It has been
customary to give these coils a relatively weak resistance I propose to give them
and also the secondary circuit of the induction coil a resistance considerably
greater than that of the wire of the line.
In theory if no account be taken of the induced currents the resistance of the
receiver should be made equal to the effective resistance of the wires, while the
resistance of the generating coil at the sending station should be equal to double
that of the wires even when the commutator before referred to is used In practice
where induced currents have to be considered it is essential to give the receiver a
resistance considerably greater than that of the line and to the generator circuit a
resistance more than double that of the line.
All the before described modifications are advantageous, not only when one or
more wires of a series are used for telephonic purposes while the others are used
for telegraphy, but also when an exclusively telephonic service is employed, and it
is desired to increase the power of transmission and to avoid the effect of induction
from one wire to another. The latter difficulty may be obviated by making the
receiver less sensitive than is customary This end may be accomplished by
increasing the distance ordinarily left between the armature and the vibrating
plate or by starting the winding of the wire of the electro magnet at a little
distance from the core or by interposing in the circuit a resistance coil.
As the induced currents created in ordinary telegraphing are most detrimental
to telephonic communication (being so abrupt as to cause induction) it is necessary
to restrict the wires used for telegraphy to currents of which the emission and
extinction is gradual and this end I may attain
1st By placing each line used for ordinary telegraphy in connection with one or
more condensers at the sending or receiving station or at any other suitable or
intermediate point. One face of the condenser being connected with the line and
the other with the earth.
2nd. By employing successive relays of suitable resistance.
3rd. By modifying the make and break mechanism so that the emission and
extinction of current will be gradual and this end may be attained in the following
manner The make and break surfaces may be formed of two plates or strips, the
upper one of which is attached at one end to the wire of the line and at the other
is connected with the receiver and thence to earth.
Said strip or spring is slightly curved so that when it is pressed down it comes

page_text: gradually in contact with the lower plate or strip which is in connection with the
battery In this manner the wire of the line will receive a current of gradually
increasing or decreasing intensity The call bells when operated by direct current
also give rise to sudden induction of current upon neighbouring lines and these
bells I prefer to operate by means of local currents and relays In order that a
message may be written down while being received the receiver may be mounted
upon a jointed and adjustable support and if two receivers are employed the
second may be moveable and adapted to be held in the hand, this one hand will
be at liberty even when two receivers are employed.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Philip Middleton Justice in the Great Seal Patent Office on the
16th September 1882.
PHILIP MIDDLETON JUSTICE of 14 Southampton Buildings in the County of
Middlesex Patent Agent. "IMPROVEMENTS IN AND CONNECTED WITH TELEGRAPHIC
AND TELEPHONIC SYSTEMS AND APPARATUS THEREFOR." A communication from
abroad by Fr Van Rysselberghe of Schaerbeek in the Kingdom of Belgium
Where a net work of wires exist which are employed for ordinary telegraphy
it has hitherto been extremely difficult to practically employ one or more of these
wires for telephonic communication owing to the injurious effects upon the
telephone of the induced, derived or "foreign currents" which each wire of the
network imparts to all the others.
The object of the present invention is to remedy this defect and to enable one
or more wires of a system to be employed for telephony whilst another or other
wires of the system are simultaneously employed for telegraphic communication.
The following are the means to be employed:
1. The intensity of the undulatory currents of the microphone and induction
coil is increased by employing an electric source of extremely feeble internal
resistance, much less than that of the primary batteries now employed upon
telephonic circuits.
2. Microphones with multiple contacts, and these coupled in quantity are used.
3. The small carbon cylinders of the microphone are, except at their points of
contact, covered with a metallic coating to render them better conductors.
4. A key is used whose mission is to put the receiver, or the secondary wire
of the induction coil out of circuit as may be required.
5. The construction of the coils of the telephone receiver and the secondary
circuit of the induction coil is modified, to considerably increase their resistances.
All the before described modifications are advantageous not only when one or
more wires of a telegraphic series are used for telephonic purposes but also when
an exclusively telephonic service is employed and it is desired to increase the power
of transmission and to avoid the effect of induction from one wire to another.

page_text: The interference with telephonic communication resulting from induction from
wires in which telegraphic currents are passing will be found to result from the
abruptness of the telegraphic currents.
By the following means this evil is lessened or removed :-
6. Appliances brought into use upon the telegraphic circuits by which the
emission and extinction of the currents is rendered gradual.
In order that the invention may be most fully understood and readily carried
into effect I will proceed to describe in detail the arrangements which in practice
are preferred.
First. The electric source in the local or microphone circuit of the telephone
transmitter.
It is of high importance that the internal resistance of this source should be tho
smallest possible because other things being equal, the smaller the resistance of
the source the greater the value of the variations in resistance of the microphone
contacts and the greater the variations in the current passing into the line wire.
The electro motive sources which most conveniently satisfy this condition and
which it is preferred to employ are:-
Planté's secondary batteries and Faure's accumulators; only one secondary cell
is used and the-charge is maintained in it by means of two Leclanche or three
Daniel's elements; or better still three Meidinger elements.
The arrangement is illustrated by Figure 1 of the drawings annexed. a is a
Faure cell say 12 inches long and 8 inches deep. bbb are three battery cells by
which the charge in the secondary cell is maintained, c is the microphone and d is
the primary of the induction coil.
The internal resistance of such an arrangement is very much less than that of
the primary batteries now used in working telephones. Other electric sources of
which the internal resistance is so small as to render them suitable for telephonic
use are:-
Thermo-electric piles, especially the piles of Clamond and of Nöe. A single
Clamond pile of 60 elements heated by one gas burner does very well.
Or the result may be attained by the use of a large number of ordinary Leclanche
or other battery cells (say 20, 30 or 40) coupled in quantity in such manner as to
reduce the resistance.
Second. The connections of the microphone.
The microphone employed may be similar to those known by the names of
"Ader" "Crossely" and "Gower-Bell." In each of these small cylinders of carbon
are pivotted at their ends into carbon blocks. For the purposes of this invention
the connections are changed so that the cylinders or preferably the individual.
pivots or contacts are each in parallel circuit with all the others. Figures 2 of the
drawings show microphones thus modified, the dotted lines indicating the
connections.
Third. The further reduction of the resistance of the microphone.
For this purpose it is convenient to deposit copper by the electro-type process
upon the carbons (excepting only the contact points) but metallic coats may be
given to them in other ways.
Fourth. The removal of unnecessary resistance from the main telephonic
circuit.
This is effected by means of a key or commutator which alternately puts the
secondary coil and the coil of the telephone receiver in and out of the main circuit
and simultaneously closes and opens the local or primary circuit.
The arrangements and the connections are illustrated by Figure 3 of the
Drawings. Here the key is arranged upon the handle of the receiving telephone
but a similar arrangement may be made to be operated by a treadle. The stem or
handle of the receiving telephone has three metal bands or contacts upon it a b
and c.
a is connected to one end of the secondary coil, the other end being to
earth. b is connected with one pole of the secondary battery and c is connected
through the microphone and the primary coil with the other pole of the battery.

page_text: It is also connected with the line wire. d is a contact insulated from the others
and the finger key e, when left free rests upon it. The spring finger key e, is in
metallic connection with c, and the contact d, is connected with the ordinary
binding screw f one terminal of the telephone coil. The other terminal of the
same coil g, is connected to earth. When the key e, is in contact with d, it is out
of contact with a and b and vice versa. In the first or receiving position incoming
currents pass from the line through the coils of the telephone receiver and direct to
earth; in the second or sending position the battery circnit is closed and the
secondary coil is in direct connection with the line without passing through the
coils of the receiving telephone.
Fifth. The resistances of the instruments in the main telephonic circuit.
The resistance in the coil of the telephone receiver as at present constructed, is
small, relatively to the resistance of the line. Now its resistance should be very
much superior to that of the line. If the line be one in which energetic foreign
currents may pass for ordinary cases 2000 ohms will be suitable.
The secondary coil in which the currents are induced by the microphone circuit
should have a much smaller resistance than it is now usual to give to it. In
ordinary cases a resistance of 20 ohms only will work well especially upon very
long lines.
Sixth. The means for graduating the currents in the telegraphic circuits.
Without in any way interfering with the ordinary working the telegraphic
circuits, the currents may be so controlled that they will not materially interfere
with telephonic working on other wires of the same system.
A very convenient way by which to graduate or control the currents and to
render the changes in the state of the circuit slower is to employ a condenser in
the manner indicated by Figure 4 of the drawings. One terminal of the condenser
is connected with the line wire and the other terminal is put to earth. When a
current is sent to the line the condenser becomes charged by the battery and a
portion of the current which otherwise would pass directly into the line is detained.
The current in the line only reaches a maximum when the charging of the con-
denser is complete and when the current of the battery is cut off, the condenser
delivers its charge into the line and lessens the abruptness of the change. The
capacity of this condenser should be about 10 microfarads.
A like result may be attained by including an electro-magnet in the circuit at
departure in the manner shown in Figure 5.
An electro-magnet with a core 15 m.m. in diameter and 50 m.m. in length and
of which the resistance is 1000 ohms is suitable.
In lieu of a separate magnet, the magnet of the receiving instrument may when
convenient, be employed.
Or a key may be employed such as is indicated by Figure 6 of the drawings.
This key first closes the circuit through a resistance and then gradually reduces
this resistance. In opening the action is reversed more and more resistance is
placed in the circuit before contact is finally broken.
In the Figure A B is a slightly curved piece of metal rocking or moving on a
pivot at C, and connected at C, with the line. DE is a small rheostat cylinder
formed of several metallic discs or rings separated by rings of semiconducting
material such as lamp black or plumbago paper. The disc E is connected with
the battery and the disc D is insulated. The rheostat cylinder is carried by a rod
pivotted at F, and it rests upon the bar A B. In the position shown in the figure
no current passes from the battery into the line, for the insulated disc D, bears
upon the bar A B but when the bar is caused to rock on its pivot C by the
depression of the key with which it is mechanically connected as shown, the discs
between D and E in succession come into contact with the bar A B and the
battery current flows into the line through less and less resistance as the movement
continues.
The total resistance in the rheostat cylinder should be about 100,000 ohms,

page_text: Having thus described the nature of the said invention and the manner of
performing the same I would have it understood that I claim :-
First. The several means herein described for the improvement of telephonic
communication.
Second. In a system in which telegraphic and telephonic communication is
carried on simultaneously, the modification of the telegraphic apparatus in such
manner as to render gradual the emission and the extinction of the telegraphic
currents, whereby interference with the telephonic communication is avoided
substantially as described.
Third. In telephonic transmitting apparatus the means of increasing the intensity
of the variations in the inducing circuit, resulting from the variations in the
resistance of microphone contacts, by employing a secondary battery or a thermo-
electric pile in the inducing circuit.
In witness whereof I the said Philip Middleton Justice have hereunto set my
hand and seal this thirteenth day of September in the year of our Lord One
thousand eight hundred and eighty two.
Signed sealed and delivered by the
said Philip Middleton Justice
in the presence of
ALLEN P. JONES
53 Chancery Lane
London W.C.
PHILIP M. JUSTICE (L.S.)