Improved Method of Telegraphing on Telephone Lines and Tele- graphic Recorders for Use in connection therewith.
Year: 1899

page_text: Date of Application, 21st Dec., 1899-Accepted, 26th May, 1900
Electrical Engineer.
Improved Method of Telegraphing on Telephone Lines and Tele-
graphic Recorders for Use in connection therewith.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 322, High Holborn, in the County of Middlesex, 6, Lord
Street, Liverpool, and 6, Bank Street, Manchester, both in the County of Lan-
caster, and Lower Temple Street, Birmingham, in the County of Warwick, Civil.
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:―
This invention relates to an improved method of telegraphing on telephone
lines and to telegraphic recorders for use in connection therewith.
Telephone subscribers will often find it convenient to have opportunity of
interchanging telegraphic messages instead of communicating verbally; this
will for instance be the case when a subscriber on being called proves to be
absent; the very possibility of being then.able to leave in writing the number
or name of the caller will prove a considerable advantage; but in the case of
important communications the transmission of telegraphic messages of some
length will also and not seldom be required because of the very fact that in
this case persons not concerned will not so easily obtain knowledge of a tele-
graphic message transmitted by one subscriber to another.
To render practicable the combination of a telegraphic system with a tele-
phonic system the following conditions should prevail:
1. The transmission of telegraphic messages should in no way influence the
calling up devices of the central station.
2. The telegraphic recorded should be switched in automatically when there
is no response at the telephone of the called subscriber.
3. The telegraphic apparatus must be sc arranged as not to interfere in any
manner with the ordinary use of the telephone system.
4. The telegraphic receiver or recorder should be so arranged as to be applic-
able to existing telephone apparatuses without substantially altering the latter.
5. The telegraphic receiver should be as simple and cheap in construction as
possible in order to be of general utility.
According to the present invention these conditions may be fulfilled by using
the call magnet inductor as a transmitter for telegraphic impulses. As is known
said inductor on calling will produce current impulses of opposite directions and
when telegraphing a message inipulses of one direction only are employed. In
this way means are provided for fulfilling the first and second conditions above
mentioned, such measures being taken that the apparatus at the central as well
as at the receiving station will be normally worked by alternating current im-
pulses while on sending current impulses of one direction only through the line
the indicator at the central station will remain uninfluenced and at the same

page_text: time au auxiliary armature provided for the call bell magnet at the receiving
and eventually also at the transmitting station will be actuated to close the cir-
cuit of a local battery which operates the telegraphic receiver.
Instead of using the magneto inductor as a telegraphic transmitter a special
inductor may be provided for the production of current impulses, only such
impulses being then strong enough to actuate the telegraphic receiver as are
induced in the secondary circuit or telephone line by the opening of a primary
or local circuit. Or the microphone inductor may be used for the production
of telegraphic impulses.
From the above brief description the whole organization of the system will
be understood. Current impulses of only one direction being sent through the
line it will suffice to fulfil the first condition simply to construct the armature
of the indicator magnet at the central station in the form of a magnet; cur-
rents of one direction in this case will not influence the armature and conse-
quently the indicator will remain at rest. The same applies to the conditions
two and three it being a very simple problem, electrically and mechanically,
to so construct the appliances of the telephone and telegraphic systems that they
will be operated only by alternating currents or currents of one direction
respectively.
In order to prove, however, that the fourth and fifth conditions can likewise
be fulfilled Figure 1 of the accompanying drawing illustrates diagraminatically
the conducting net-work of a system of the kind referred to in which the
magneto-inductor serves to produce the telegraphic impulses. indicates the
central station wherefrom wires lead to the joint 36 on one subscriber's appa-
ratus (101) and to a point 37 on that of the other (102). Two special wires issue
from these points one of which 3 leads to a point 10. The wire 2 issuing from
the bobbin 9 can be connected by means of a switch lever 8 with said point 10
or with a point 11. If at the station 101 this lever is in contact with the
point 10, this being the normal position the calling current will flow as follows:
From the magneto-inductor 7 (subscriber 101) to the bobbins 9 of the call
bell through connection 2 and arm 8 to point 10, wire and point 36 to the
central station O whereat the indicator will drop, the calling current being an
alternating current. From the central station the calling current will pass
through the line, point 37 and wire 3 to point 10, hence through the arm 8 and
wire 2 to the bobbins 9 of the call bell and then into the earth at the receiving
station. If no answer is received and the calling subscriber desire to send a
telegraphic message the lever 8 will be moved to the point 11 (shown in full
lines at 101). By now turning the crank which is preferably for the purpose
of telegraphing provided with a little handwheel the current will flow as
follows:-
From the magneto inductor 7, subscriber 101, through bobbins 9 of the call
bell, connection 2, arm 8, point 11, and wire 4, to bell clapper armature 15.
If the bell clapper 13 is in opposite position to that shewn the current impulse
will pass via point 12 and wire 5 into earth. When, on the contrary, the clapper
has been shifted to the position shewn in the drawing the current impulse of
opposite direction will flow through point 14 and wire 6 point 36 via the central
to the receiving station. Inasmuch as current impulses of one direction
are conducted to earth and currents of the other direction only
caused to flow through the line, the indicator at the central will remain un-
influence because of the polarization of the armature of the same.
The course
and effect of these current impulses at the receiving station will be as follows:
From point 37 through wire 3, switch lever 8, wire 2, and bobbin 9 of the
call bell and hence via wire 1 to earth. The currents being uni-directional the
call bell remains at rest. The armature 16 on the contrary is attracted at each
current impulse thereby closing whenever it is attracted the local telegraphic
circuit (19) by moving the armature contact 17 into contact with the point 18.
The closing of the circuit at this point solves the problem as it will be seen

page_text: that both current schemes are practicable without in one case the telegraphic
appliances and in the other the telephone appliances being influenced.
The whole arrangement may be additionally simplified by using a special
inductor instead of the magneto inductor to produce the telegraphic currents,
this arrangement being shewn in Figure 2.
Referring now to this fig., 50 indicates the microphone inductor, 51 the tele-
graphic inductor, 52, the telephonic and telegraphic battery. 53 is a telegraphic
key which actuates two contact levers 54 and 55. Said contact levers are so
connected with the telegraphic key 53 as to be simultaneously movable by means
of the latter. By this arrangement the contact lever 54 can be moved into
contact with one or the other of the contacts 56, 57 and the lever 55 with one
or the other of the contacts 58, 59, means being provided, however, to prevent
lever 54 from leaving contact 57 before the connection at 59 has been inter-
rupted. The normal position of the contact key is that shewn in full lines.
Supposing now the subscriber 102 to be called the calling current will flow
as follows: From the line through the bobbins 9 of the call bell magnet to
contact 56 through the telephone receiver which may also be excluded from
the circuit when hanging on its arm through the secondary coil of the telephone
inductor 50 and ground line 60, the call bell operating meanwhile in the normal
manner. Should the called subscriber at 102 be absent the calling subscriber
at 101 can transmit a telegraphic message by moving the key 53 forward and
backwards no other measures being required for this purpose. On moving the
telegraphic key 53 to the left the contacts 57 and 59 are brought into contact
with the levers 54 and 55 respectively thereby setting the local battery 52 in
operation; it will be seen the local circuit will pass the primary coil of the
transformer 51 (52, 73, 72, 55, 59, 61, 51, 62, 65, 52). By closing the local
circuit as well as by opening the same a current will now be induced into the
secondary coil of the transformer; it is evident this current will flow as follows:,
From earth at the transmitting station 101 to 60, 51, 57, 54, 9, central
station (subscriber 102), 54, 56, telephone receiver, 50, 60 to earth at the
receiving station 102. Of these induced current impulses those produced by clos-
ing the primary or local circuit are very weak and will not consequently cause
any disturbing effect whatever either at the central or at the receiving station.
The induced current impulses of opposite direction produced by opening the local
circuit, on the contrary, are strong enough to cause the armature 16 to be
attracted, thereby closing the contact 63, 64 and hence a current from the local
battery 52 will be sent through the telegraphic system 67. The course of this
current is as follows:-52, 73, 72, 71, 64, 63, 16, 68, 67, 66, 65, 52.
In order to provide for the transmitting subscriber a copy of the transmitted
message the bobbins of the call bell are always included in the main line even
when the telephone receiver has been removed.
In this way it is rendered possible besides for the calling subscriber to keep
the telephone receiver to his ear even while telegraphing and this will often be
found convenient. The switch lever 66 operates to exclude the telegraph
receiver if the calling subscriber desires no copy of the transmitted message.
As a circuit closer for the telegraphic circuit magnet a special relay may also
be used instead of the call bell, the armature and contact of which relay are
adapted to be easily movable and constructed with minimum inertia or said
relay may be arranged in a vacuum.
:
As to the telegraphic receiver or recorder it is to be observed that it may be
constructed so as to be operated entirely by the current impulses produced in
the local circuit and such simple construction would fully suffice for the object
in view.
Figure 3 illustrates the construction of a telegraphic receiver on this basis.
Two electro magnets 20 and 30 are included in the local circuit 19. At each
closure of the current the magnet pole 21 will cause the armature 22 to oscillate
in the direction of the arrow; the armature lever 23 as well as another lever 24

page_text: +
are loosely mounted on the shaft to the ratchet wheel 25 but by means of a
short lever 26 (on the armature lever 23) engaging a stud 27 (on the lever 24)
the latter may be moved along with the armature lever 23 while on the return
the armature drops freely back into its normal position. Such movement of the
armature causes the retracting spring 28 to be stressed thereby revolving by
means of a pawl 29 the ratchet wheel 25 which is geared with the feed roller 35
between which and the roller 34 the paper filler is fed forward. The driving
gear is connected in the usual way with swing and floating wheels.
The tracer is carried by a lever which has mounted upon its other end an
armature 31, influenced by an electro magnet 30 and said tracer as will be seen
normally bears upon the paper strip on the support roller 33. The code symbols,
therefore, are not produced in the ordinary manner, but by causing shorter or
longer intervals between each transmitted current impulse thereby causing the
line to be subdivided according to the particular code system in use.
By such an arrangement of the tracer as is shewn in the drawing the code
symbols will appear as indicated on the issuing paper filler. If the tracer is
caused to vibrate laterally symbols are correspondingly obtained like those
indicated in Figure 4.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, as communicated to
me by my foreign correspondent, I declare that what I claim is:-
1. Method of telegraphing on telephone lines in which
a) Current impulses of one particular direction from an induction coil are
employed directly or indirectly to produce the code symbols.
b) At the central station, the armature of the indicator magnet is polarized
so as to remain uninfluenced by current impulses of one particular
direction, it becoming possible in this way to use the call bell inductor,
the telephone inductor or a special inductor as a transmitter for the
telegraphic symbols without influencing in any way either the indicator
at the central station or the telephone appliances at the receiving
station.
2. The system of telegraphing over telephone lines as described with reference
to Figure 1 or to Figure 2 of the accompanying drawings.
3. A telegraphic receiving system constructed and operating substantially as
- described with reference to Figure 3 of the accompanying drawings.
1000
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.