Improvements in and relating to Telegraphic Transmitting and Receiving Apparatus.
Year: 1897

page_text: Date of Application, 6th Apr., 1897-Accepted, 5th June, 1897
COMPLETE SPECIFICATION.
Improvements in and relating to Telegraphic Transmitting and
Receiving Apparatus.
A communication from abroad by BERNHARDT HOFFMANN, of 10 Rue Sauchat, Paris,
France, Contractor for Public Works.
I, JOHN CLAYTON MEWBURN of the Firm of J. C. Mewburn and Ellis of 55 and 56
Chancery Lane in the County of London, Chartered Patent Agents, do hereby
declare the nature of the said invention and in what manner the same is to be
performed to be particularly described and ascertained by the following statement :-
This invention has reference to telegraphic transmitting and receiving apparatus
and has for object to simplify and improve the construction and operation of apparatus
of the character described in the Specification of the said Bernhardt Hoffmann's
Letters Patent No. 24076 of 1894. This object is attained by the improved and
modified apparatus hereinafter described, which will be fully understood from the
following description and from the annexed drawings in which
Figure 1 is a diagram showing two apparatus connected up the one being in the
transmitting position and the other operating as a receiver.
Figure 2 is a front elevation, Figure 3 a plan and Figure 4 a side view of an
apparatus constructed according to the present invention.
The other figures show details.
Upon the spindle A, which is driven by a clockwork movement, is a wheel B, which
I will call the type wheel, and which carries on its periphery the different signs or
characters to be transmitted; on the same spindle is mounted an escapement wheel C
allowing of the intermittent rotation of a clockwork movement which drives this
spindle; an arm D carrying two metallic brushes a and b is mounted on the opposite
end of the spindle A to that which carries the wheel B and rotates with an intermittent
movement in front of a ring of contacts or distributing crown E. The brush b rubs
upon a second contact ring F, interrupted at c, the purpose of which will be explained
later.
The brush a in its rotation rubs successively over a series of sectors w x y z &c.,
28 of which are shown in the drawing (Fig. 5), these being normally insulated
from each other and respectively connected with the keys of the keyboard of the
machine.
The brushes a and b are respectively connected to the rubbers d and e which bear
upon insulated collars to which they transmit the current.
The keys of the machine are alternately in communication with one of the positive
poles of the line battery H by springs ³ ³ ³ ³ &c. or insulated from that pole by the
springs. Upon depressing one of the keys in communication with the battery
this latter is cut out of the circuit, because the corresponding contact springs are
thereby caused to press against an insulated portion of the key; on the other hand, by
depressing one of the insulated keys, the battery is placed in communication with
the line.
The movement of the wheel C is controlled by any suitable escapement (in Figure 1
of the drawings it is shown as a double balance-wing escapement). The escapement f
is carried by the armature g of an electro magnet h, the solenoids of which are

page_text: arranged to act independently of one another and to attract the armature g either to
the right or to the left. The armature is polarized, and in order that it may be
attracted to the one side or the other it is necessary to develop in the solenoids
opposite polarities to those of the said armature.
When the coils of this electro magnet are alternately traversed by a current, the
escapement wing oscillates between the escapement teeth and the wheel C escapes one
tooth at each movement, and the brush a then turns to the extent of one division of
the contact ring E.
There is a relay electro magnet k the object of which is to send currents alternately
into each of the coils of the electro magnet h. For this purpose, the armature of the
relay is connected with the one pole of a local battery I while the other pole of this
battery is connected to earth; the two contacts Im between which this armature moves
are connected respectively to the two coils of h.
The spindle A also carries a wheel J provided with curved teeth, say 28 in number,
(this number being equal to that of the contacts of the contact ring E); above this
wheel is a spring n carrying a finger o which is lifted each time a tooth of the wheel J
passes beneath it. This spring n is connected at one end to the local battery I and
carries at its other extreinity a pin which may be in communication with a contact
connected to the printing electro magnet K. Every time the finger o falls into a gap
of the wheel J, the current from the local battery is closed in the electro magnet K,
but by reason of the rapidity of the operation of the apparatus, the spring is thrust
back and the contact is only established for a period which is too limited to allow the
electro magnet K to act; practically this spring rarely touches its bearing. It is only
when a character is printed and the apparatus stops, that the finger o can enter
sufficiently into the gap of the wheel J and the duration of contact becomes sufficient
to allow the electro magnet K to operate.
The apparatus also comprises two keys L and M and a button Othese being
situated above the keyboard and acting upon springs in order to effect the different
communications between the parts of the machine, and between the apparatus which are
in communication with each other by the line.
In the following description it is supposed as an example that the apparatus
combined with a telephone branched on the same line when the keys L and M are
raised. This telephone is in communication with the apparatus by the terminals t t.
Referring to the scheme of Figure 1, in which apparatus No. I is in the transmitting
position and No. II in the receiving position, the path of the currents will be as
follows:-
e,
The current passes over the lead 1 to the springs 2 and 3 of the button O, the
wire 4, the springs for example, wire 5, contact Y, brush a, rubber wire 6,
springs 7 and 8 of key M, wire 9, electro magnet k, wire 10, springs 11 and 12 of
key M, connection 13, springs 14 and 15 of key L, wire 16 and terminal 17 of the
line wire.
At the receiving station No. II, the key L¹ being alone depressed, the current
arrives by the terminal 18, wire 19, springs 20 and 21 of key L', connection 22,
springs 23 and 24 of M', wire 25, relay electro magnet. k, wire 26, springs 27 and 28
of M³, wire 29 and terminal 30 connected to a second line leading to terminal 31 of
the transmitting apparatus, or preferably to earth, this latter terminal being then
situated at earth.
In each of the two stations the armature of the electro magnet k is attracted, its
extension comes into contact with one of the two contacts or m, closes the local
circuit by 32, 33, 1 or m, electro magnet, wires 34, springs 35 and 36 of key L,
wire 37, armature of electro magnet p, wire 38, and returns to the battery I by the
terminal 39. The armature g of electro magnet / being attracted causes the escapement
wing to move, the ratchet wheel C escapes one tooth and the brush moves forward
upon the distributor E.
The following sector, z for example, being insulated, the line current is interrupted,
the electro magnet k allows its armature to return to rest, a local circuit is closed

page_text: through the second electro magnet of h, the armature 9 is attracted in the opposite
direction, and the escapement operates afresh.
There has thus been obtained at the two stations a synchronous forward movement
of the brushes a and consequently of the type wheels B.
Suppose now that the brush a, leaving a sector in connection with the line battery H,
comes upon the following sector, which instead of being insulated is also put in
communication with the battery by the depression of the key which corresponds with
it on the manipulating keyboard; the armature & remains attracted, the local current
passes into the same coil of as at the previous moment and the escape.ment ceases to
act; the mechanism stops.
The same things occur in identically the same way if the brush a, leaving an
insulated sector, comes upon the following one which has just been insulated by
depressing the corresponding key; the arinature of k not being attracted at this
moment remains at rest, and sends as at the preceding instant a local current into the
same coil of h; the escapement no longer acts.
At this moment the spring n bears upon the contact p, because the finger o enters
into the gap of the wheel J which has followed the movement of the brush a; a local
current passes through 32, 40, n, p, 41, electro magnet K, and returns to the battery
by 34, 35, 36, 37, 38 and 39; the electro magnet K attracts its armature and brings
the roller y and the paper which it carries in contact with the type wheel; the printing
is effected at this moment and the character corresponding to the key depressed
appears on the paper.
The current coming from the earth terminal 31 follows the lead 42 through the
springs 43 and 44 of the button O, the wires 45, and the second terminal 46 of the
line wire, completing the circuit. If the button O is depressed, the current coming
from the terminal I passes through the springs 47 and 43, then returns by 42 to the
terminal 31 of the line; the current is thus reversed by this operation.
This reversal of current is utilize to obtain synchronous starting of the two
apparatus at the commencement of a communication, or even in the course of same.
For this purpose, the relay n' is polarized ;. its armature connected with the electro
magnet has already explained carries a contact piece by means of which it is further
put into communication either with the local battery I by the wires 38 and 39, or
with the wire 48 and the brush d by the one or the other of the contacts between
which it vibrates. There is a branch wire 49 from wire 38 which establishes
5 communication between the latter and the continuous portion of the contact ring F,
and the contact c of this latter is insulated.
So long as the current flows in the normal direction, that is to say so long as
the button is raised, the armature of the electro magnet n', which is in the line
circuit, remains in contact with the lower contact (38) which connects with the
local battery; but as soon as the current is reversed by the depression of the
button as before explained the armature of n' comes against the other contact and
puts h in communication by 48 with the rubber d; the current returns by the latter
through b, F, 49, 38 and 39 to the local battery.
When in consequence of the rotation, the brush b comes upon the contact c,
5 which is insulated as above stated, the current from the local battery is cut off from
the electro magnet h, which ceases to act and the whole arrangement stops in this
position.
5
To send a call, the bell call button of the telephone is pressed, the keys L, M
and O of all the stations being raised.
To transmit, the transmitting station depresses L and M, and to receive, the
receiving station depresses L' only, as seen in Figure 1.
In this position, the transmitting station, by depressing the key O, sends a current
of reverse direction to the normal into the two apparatus in order to establish their
synchronism.
Suppose the receiving station to be in advance of the transmitting station;
apparatus work together until at the receiving station the brush & comes upon c; at
the

page_text: this moment the whole arrangement at the receiving station stops and the trans-
mitting station continues to work until its own brush b also comes upon its sector c;
pressure is then removed from the key O and the two apparatus work synchronously
together.
If on the contrary it is the transmitting station which is in advance of the other,
the two apparatus stop when the brush 6 comes upon the insulated sector c at the
transmitting station, since it is the latter which produces the emissions and
interruptions of the line current. It is then only necessary to lift for an instant the key 0;
the two apparatus have then advanced together to the extent of one contact, but it is
now the receiver which is in advance of the transmitter; by at once depressing
the key O the apparatus are again set in operation and the case is the same as the
preceding, the receiver stops first.
It is therefore desirable, before commencing to transmit to press twice upon the
button to ensure the synchronous starting of the two apparatus.
The parts of the apparatus shown in Figure 1 are indicated by the same letters of
reference in Figures 2, 3, 4 and 5, Figure 5 showing the distributing ring or crown.
I will now proceed to describe certain details of construction.
It has been seen that the type wheel is arranged to rotate by intermittent move-
ments each of one twenty-eighth of a revolution; in order to increase the facility of
working the apparatus this wheel is adapted to print a number of characters twice as
great as the number of contacts of the contact ring C.
For this purpose the characters or signs engraved on this wheel are arranged in
two series one above the other peripherally of the wheel, for example in the
following order A1 B2 C 3. The type wheel turning 1/28th of a revolution at each
movement of the brush a, the characters are presented in the order A B C D .
or 1 2 3 4 according to the position of this wheel with respect to its axis,
that is to say that in order to produce the one or the other of these two series it is necessary
so to speak to shift the wheel 1/56th of a revolution with respect to its spindle.
The arrangement which is employed for this purpose is represented on a larger
scale in rear elevation Figure 6 and in side view Figure 7.
The letters of the alphabet alternated with the figures and the signs of punctuation
or expression are engraved upon the periphery of the disc B. There are in all
56 divisions, 52 of which are allotted to the letters, figures and signs and the four
others to the spaces for the letters and to the spaces for the figures. The same key
of the keyboard therefore allows of printing two different characters according to the
position of the disc.
Behind the disc B and loose on the spindle A are arranged two arms r s each
formed with a hole u and a bevelled noses. Above these arms are springs
each carrying a pin 33. The two arms rs are at any suitable angle to each other
this being determined by the position on the disc of the spaces of letters and figures ;
the angle of 22 differs from that of rs by 1/56th of a revolution in such manner
that never more than one of the pins ³ ³ may take into the corresponding hole. The
springs have bevelled pieces rs. A piece having a bevel v' and an angular
nose is fixed behind the lever which carries the printing roller q.
When the key which corresponds on the keyboard to one of the spaces is depressed,
the printing lever rises, the nose of the arm r lifts the spring 2 or which is
opposite it and disengages the corresponding pin ; at the moment this pin is disengaged
the nose v strikes the extremity of r or s, whichever is opposite it, and causes this to
be deflected and to carry with it the disc B to the extent of 1/56th of a revolution; on
the other hand, the spring being fixed on spindle A, remains in place, and the second
pin 3
or enters into its hole, thus firmly securing the spring and consequently
the spindle with the disc B.
The paper P from an ordinary reel passes over a roller 9 provided at its circum-
ference with fine sharp teeth. A spring fork (Fig. 8) presses the ribbon of paper
upon the roller, space being left between the forks of the spring for the periphery of
the type wheel.
The forward movement of the paper is effected as follows. A ratchet wheel R

page_text: is secured on the roller q, a pawl S being secured on one of the plates of the
casing of the apparatus and gearing with the ratchet wheel. When the printing
electro magnet operates, the arm which carriel the roller q rises, the paw! rides over
the ratchet wheel R and the impression is produced. When the current ceases in
the electro magnet K, its lever returns to its original position, and the pawl being
in gear with its ratchet wheel causes it to rotate with the roller q, and consequently
moves the paper forward a distance determined by the construction of the apparatus.
Figure 9 represents in elevation the wheel J with curved teeth provided with its
spring and finger o; the current from the local battery arrives at the base of the spring
at 40 (Figure 1); it passes to the printing electro magnet by the contact when the
finger o enters completely into a gap between two teeth of the wheel J.
P
It has been before explained that in order to establish synchronism with certainty
between the two apparatus, it suffices to twice depress the normal current reverser
button O, the second depression of this button should be effected immediately it has
been allowed to rise and this is extremely difficult in view of the rapidity of rotation
of the brush a. To obviate this difficulty there is arranged a small accessory part
which allows of stopping the apparatus at synchronism without being limited by a
shorter or longer interval between the two manipulations of the button O. This
arrangement is shown separately in Fig. 10.
Upon the spindle A of the type wheel is fixed a cam T, which at each revolution
causes rotation of a star wheel U to the extent of one tooth; this star wheel carries a
drum V divided into an even number of alternately conducting and insulated
sectors.
The conducting sectors are in electrical connection with each other; two springs XX¹
bear upon the surface of the drum V at two diametrically opposite points in such
manner that they are in electrical connection with each other when they bear upon
metallic sectors of the drum. One of these springs X is in electrical communication
with the sector c of the synchronizing contact ring or crown; the other with a
spring Y of the button 0 (which in this case is provided with a metallic contact
piece at its lower part). Another spring Z of the button O is in electrical comm.uni-
cation with the full part of the synchronizing ring.
When the button O is depressed the contact ceases to be insulated when the two.
springs X and X' bear upon metallic sectors of the drum V; at the next revolution.
of the spindle A and therefore of the cam T the contact e will be insulated, because.
the two springs X and X' bear upon insulating portions of V. It is only at this
moment that the transmitter stops.
At the receiving station the button O not being depressed, all takes place as if the
star wheel and its accessory parts did not exist.
By means of this arrangement synchronism will only be effecte 1 at the transmitting
station once in two revolutions, while at the receiving station it is enabled to be
effected at every revolution; the receiving apparatus will await the stoppage of the.
transmitter so that the two apparatus may recommence working together.
As the printing electro magnet does not operate until pressure is applied to O
it is possible to bring the apparatus to synchronism at any time, even in the middle
of a word.
Whenever a transmission is finished it is desirable to twice establish synchronism,
keeping the button O depressed (to prevent the re-starting of the apparatus). When
the apparatus stops for the second time and it is desired to leave it in the receiving
position, the lever M is lifted. If it be desired to substitute the telephone for the
telegraphic apparatus, the two lovers are lifted; in the latter case the local battery
is cut out; no part of the apparatus works.
Having now particularly described and ascertained the nature of the said inven-
tion as communicated to me and in what manner the same is to be performed
I declare that what I claim in respect of telegraphic transmitting and receiving
apparatus of the kind hereinbefore referred to is
1. The arrangement of keys or levers L and M in such manner that the apparatus

page_text: may be caused to act at will. either as a transmitter or as a receiver substantially as
hereinbefore described and represented in the accompanying drawings.
2. The arrangement of a reversing key O in such manner that the transmitting and
receiving apparatus may be stopped in the starting position, in combination with a
ring or crown F carrying an insulated contact by means of which the auxiliary
current of the local battery may be cut off and the instruments prevented from
working when they are in this starting position, substantially as hereinbefore
described and represented in the accompanying drawings.
3. The arrangement described with reference to Fig. 10 whereby synchronism of
the instruments can be ensured without necessity for rapid manipulation of the
current reverser button, the insulated contact of the synchronising crown F being
put in electrical connection with the full part of the crown and therefore with the
local battery once in every two revolutions of the transmitting apparatus, the trans-
mitting apparatus stopping only at the second revolution substantially as hereinbefore
described.
4. The arrangement of a type wheel having a number of divisions double that of
the contacts on the distributing contact ring (E), whereby a double number of
characters may be printed, the characters being disposed in alternate series around
the periphery of the wheel, and either series being brought into action by depression
of a corresponding key of the keyboard, substantially as hereinbefore described with
reference to the accompanying drawings.
5. The mechanism substantially as hereinbefore described whereby the type wheel
may be shifted with respect to its spindle, the said mechanism comprising a double
spring carrying two pins and mounted upon the driving spindle of the apparatus, one
or other of these pins being always engaged in a socket formed in a piece fixed to
the type wheel loose on its spindle, the shift of the wheel being effected by a finger or
nose carried by the printing lever which lifts the end of the spring that is opposite it
and disengages the pin, rotates the disc the necessary distance to cause the second
pin to take into its socket and secure the driving spindle and the type wheel
together, substantially as hereinbefore described and represented in the accompanying
drawings.
6. The arrangement of a wheel provided with curved teeth acting upon a spring in
order to cause the said spring to vibrate above an electric contact, this contact being
only established during stoppage of the driving spindle, with the object of allowing
the printing electro magnet to act only when the driving spindle is stopped,
substantially as hereinbefore described and represented in the accompanying
drawings.
7. The arrangement of the printing roller q having fine sharp teeth, in combination
with a spring fork retaining the paper upon this roller, the said roller also carrying
a ratchet wheel actuated by a fixed pawl, whereby the paper is intermittently moved
forward when the roller returns to rest from the printing position after the printing
of a character, substantially as hereinbefore described and represented in the
accompanying drawings.
8. The general construction and operation of telegraphic transmitting and
receiving apparatus, substantially as hereinbefore described and as represented in the
accompanying drawings.
Dated this 6th dow of Am:11007
=
J. C. MEWBURN & ELLIS,
55 and 56, Chancery Lane, London, Chartered Patent Agents..