IMPROVEMENTS IN METHOD AND APPARATUS FOR TELEGRAPHY
Year: 1885

page_text: I JOHN CHARLES LUDWIG residing at 728 Cass Street in the City of San
Francisco, in the County of San Francisco, and State of California, in the United
States of America Electrician do hereby declare the nature of my invention for
IMPROVEMENTS IN METHOD AND APPARATUS FOR TELEGRAPHY and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement:―
My invention relates to a method and apparatus for producing and transmitting
electric currents for telegraphic purposes, its object being to provide strong and
highly efficient currents for this purpose while obviating the maintenance of large
and continuously expensive voltaic batteries or ponderous power driven mechanical
generators.
The currents I use are produced by magnetic induction and are different from
those produced by ordinary induction coils which have heretofore been used in
telegraphy and while the currents of my system have a character similar to that of
currents from magneto or dynamo electric machines the mode of their production.
is vastly different in that there is in it required no movement of any part of the
generator, other than a finger-key In the preferred form of the apparatus the
simple making and breaking of a circuit of a small battery by means of an
ordinary transmitting key, serves to magnetize and demagnetize an electro-magnet
which by its alternations of conditions effects in suitable adjacent coils surrounding
magnetic cores, the induction of electric currents which traverse the line wire
alternately in opposite directions and actuate relays or other receiving instruments
constructed for operation by such reversed currents.
In what my improvements consist will be readily understood from the following
particular description and definite claims in connection with the accompanying
drawings in which
Fig 1 is a perspective view of a current generating and transmitting apparatus
constructed according to my invention.
Fig. 2 is a side elevation and Fig. 3 an end elevation of the same.
Fig 4 is a side elevation of a preferred forın of receiving instrument.
Fig 5 is a top view of the same.
Fig 6 is a diagram illustrating a system of telegraphy comprising my invention.
Fig 7 is a side view of a current reversing key. Referring to Figs 1, 2 and 3
the letters A and A¹ indicate two permanent magnets of the ordinary horse-shoe

page_text: form arranged flatwise with relation to each other and at a suitable distance apart
one being above the other in the present instance though such relative positions
are non-essential. Between the permanent magnets near their current ends stands
a block of wood b or other isolating material which serves to keep them separated
a proper distance at these ends. Each pole of both permanent magnets is provided
with a laterally projecting sofe iron pole-piece a the pole pieces of one magnet
extending toward those of the other and separated therefrom a suitable distance.
Each pole-piece is surrounded by a coil C of insulated fine wire about the size
preferably of ordinary Morse relay wire. The coils of each magnet are connected
in a pair by their inner terminals and the two pairs are connected together
between two similar outer terminals as shown by the wire c that is the coil on
one south pole-piece has its outer extremity connected to the outer extremity of
the 'coil on the other south pole-piece The outer extremities of the other two
coils are to be connected to earth E and the line L respectively. The coils are all
similar in their winding and the manner of their connection brings the winding
in proper relation to the respective pole-pieces for instance if a current in a given
direction should enter a coil of one magnet by its outer extremity it would leave
by its inner extremity and pass to the inner extremity of the opposite coil of the
same magnet and then leaving this coil by its outer extremity it passes to the
outer extremity of the similarly situated coil of the other magnet. By this
arrangement induced currents simultaneously produced in all the coils by the north
and south pole-pieces are caused to flow in the same direction while if the
coils were connected so that the outer extremity of one joined the inner extremity
of another the simultaneous inductive influences of opposite poles would neutralize
each other in the coils and no current would flow. The letter D indicates an
electro magnet having coils of large wire so that its cores will be promptly and
efficiently magnetized when said coils are traversed by an electric current.
The yoke piece d of the cores of this electro magnet is fastened to the block b
and the polar portions of said cores as shown clearly at f in Fig 2 are somewhat
flattened and extend between the tips of the opposite pole pieces of the permanent
magnets being prevented from touching said pole-pieces however by thin inter-1
posed plates g-of isolating material such as hard rubber, wood or paper One of
the coil terminals of the electro-magnet D is connected to a binding post p and the
other to a similar post p¹ on base board B The apparatus is secured to the
baseboard by suitable bolts y and bars y¹. The binding post p is connected with
one pole of a small voltaic battery X the otlier pole of which is connected with
the anvil or circuit closing contact of an ordinary transmitting key K the key
itself being connected with the binding post p¹.
The permanent magnets A and A have poles of opposite character arranged
opposite each other that is the tip of the north pole piece of each magnet faces and
is adjacent to the tip of the south pole piece of the other magnet and in the space
between each opposed pair of tips and also in a limited contiguous space is com-
prised an intense magnetic field If a piece of soft iron or a magnet were moved
through this field athwart and between the opposed polar tips currents. would be
induced in the coils but a view to obviating the necessity of moving an armature
with relation to the pole-pieces I have arranged perinanently between the soft iron
poles of the electro magnet and I have found that alternate magnetization and
demagnetization of the cores of this electro magnet effect, in an increased degree,
the purpose which would be accomplished by moving an armature through or
alternately into and out of the magnetic field In other words the intermittent
magnetization of the electro magnet or better still reversing its magnetic polarity
by currents alternately in opposite directions through its coils results in the induc-
tion of very powerful currents alternately in opposite directions in the coils of fine
wire C which surround the pole pieces of the permanent magnets the strength of
such currents depending first on the strength of the permanent magnets, secondly
in the size of the wire used on the spools C and thirdly on the battery power used.
The stronger the permanent magnets the more intense the currents produced and

page_text: il terminal of the small
the other to a similar
the line wire L and the
the intensity is also enhanced in proportion as the wire of spools is finer A single
small-sized bichromate of potassium cell is sufficient battery for all ordinary
purposes and will produce a proper magnetization to induce a current sufficient to
overcome a resistance of more than forty thousand ohms which is the resistance of
about two thousand miles of No 10 galvanized iron wire such as commonly used
in practical telegraphy. It will of course be understood that in using the reversed
currents produced by my generator for telegraphing by the Morse code, a suitable
receiving instrument must also be used and such an instrument I have illustrated
in Figs. 4 and 5, in which M designates a permanent magnet of horse-shoe shape
with one limb attached to a base board m and the other lying above it. Directly
to the pole of this upper limb is secured the yoke piece of a small electro magnet O
the coils q, q' of which have soft iron cores, to which of course is communicated
a magnetic polarity the same as that of the permanent magnet pole to which their
yoke piece is attached. In front of the poles of this small electro-magnet is an
equal armed oscillating armature R the middle of which is fastened to a vertical
arbor S which is stepped in a bearing t at its foot and has a top-bearing in the
overhanging arm t¹ of a metal post T. Behind one end of the armature R is
arranged an adjustable contact soreen u supported in a metal post v. The metallic
step bearing t and post T are connected by a wire was shown in dotted lines Fig. 5
with a binding post p' and the post U is connected by a wire w also shown in
dotted lines with a binding post p³. To these two binding posts p³ p³ are to be
connected respectively the wires of a local circuit including a local battery X¹ and
a sounder S¹ as shown in the diagram Fig. 6. One
electro-magnet O is connected to a binding post p
post p. In Fig. 6 the post p³ is shown connected
post p is connected with a small switch J which may be swung to contact
buttons or 3, the former being connected directly to ear while the latter is con-
nected to earth through the coils C of the generator. The mature R of the relay
is entirely neutral and made of soft iron. It is arranged ite close to the poles of
the electro magnet O and when no current traverses the co of said magnet it will
be attracted equally at both ends and if either end is psed closer to one pole
than the other the armature will remain in such positio.. as long as no current
passes and also while a current in a given direction is passing as will presently be
explained. Referring now to the diagram Fig. 6 I will explain the operation of my
invention recurring also occasionally to some of the other figures. In the diagram
I have indicated two telegraph stations by name as Station N° 1" and
"Station N° 2" The sets of apparatus at the two stations are precisely alike
each set comprising a generating and transmitting instrument, a transmitting key
and battery connected therewith, a relay and local battery circuit including a
sounder and a switch and connections by which the relay may be connected directly
to earth or to earth through the coils C of the generator The relays at the two
stations are connected by the line wire L. Ordinarily when the line is not in use
the switch J will be turned, to contact with button j at each station thus connecting
the relays directly to earth and removing the resistance of the generator coils from
the line. Now suppose Station No 1 desires to send a message to Station Nº 2.
The first step is to turn the switch J at Station No 1 to contact with button *
thus putting the generator and transmitter to line Then by operating key Kat
Station No 1 a signal for calling Station Nº 2 is sent and received at the latter
station by means of its relay and sounder as its relay is connected to ground.
At Station N° 1 after sending the call the generator is preferably removed
temporarily from the line (though not necessarily) which should be connected
directly to earth while the answer to the call is awaited. The answer having
announced that Station N° 2 is ready to receive the message the generator at
Station No 1. is again connected to line and the operator by using the key K in
the usual manner may send his message according to the ordinary Morse code. If
a simple make and break key is used each time it is depressed and the circuit of
battery X closed, the cores of electro magnet D will be magnetized and by their

page_text: action on the magnetic field and the cores of spools C there will be induced in said
spools a current which will pass say from the spools to line and also from earth
through the spools.
.
When the key is opened and the cores of magnet D demagnetized a reverse
current traverses the line and spools. Now we will suppose that in the con-
struction of the relays the electro-magnets O are attached to the north poles of the
permanent magnets M and a north polarity is consequently communicated to the
Boft iron cores of said electro magnets. Suppose further that the induced current
generated and sent on the line as the result of closing the key flows in such
direction through the coils of the relay electro magnets that were the cores of said
magnets neutral the current would give to core of spool g a north polarity and to
core of spool g¹ a south polarity. Now it is obvious that the cores already have a
north polarity the effect of the current will be to make stronger the north polarity
of core of coil q and weaken it not altogether neutralize that of core of coil g' so
that the core of coil q will have the strongest attraction for the armature R and
will draw the adjacent end of said armature toward it, throwing the other end out
against the contact screw u and thus closing the local circuit and operating the
sounder at both stations. No reverse current will flow until the key is opened
(although the magnetizing effect of the direct current will cease almost instantly)
and consequently the armature will remain attracted by the pole to which it is
nearest until the key is opened and will keep the local circuit closed meantime.
As soon however as the key is opened the demagnetization of the cores of electro
magnet D causes a reverse current to traverse the line and coils of the relay and
this reverse current weakens the power of the cores of coils q and reinforces that
of cores of coils q so that the armatures R are drawn away from the contact
screws u the local circuits are opened and the sounders make a back stroke. It
will thus be seen that the intervals of movement of the relay armatures may be
made to correspond to the "dots" and "dashes" of the Morse code of signals. It
will be observed that but one pole of the permanent magnet is made use of in my
relay the other pole being not made use of to magnetize the armature as in the
ordinary polarized relay. If the armature of my relay were magnetized the
instrument would be inoperative, as the end corresponding to or rather having
opposite polarity to that of the coil would be always attracted and that delicate
balance of power between the two cores upon which the prompt and vigorous
action of the relay depends would be destroyed. This relay may be disconnected
from a local circuit and used as a sounding receiver directly. I have illustrated
that instead of simply making and breaking the circuit through the coils of electro
magnets D of the generator, the currents may be reversed through said coils In
Fig 7 I show a current traversing key which may be used for this purpose
operation is obvious and will not therefore be particularly explained.
t
Its
I do not limit myself to the precise means shown for varying the magnetic
character of the stationary body of metal as it might be varied in other ways than
by making it a part of the core of an electro magnet without departing from the
spirit of my invention. I would further say and it will be readily understood that
my invention as respects the generator and transmitter is not limited to any
particular number of pairs of opposing pole-pieces and coils. There may be but
one pair or any convenient number more than two as shown it being only necessary
that the system of connecting the coils which I have indicated shall be followed.
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
1. The hereindescribed improvement in the art of generating induced electric
currents for telegraphic and other purposes the same consisting in varying the
magnetic character of a stationary body of metal adjacent to inagnetically polarized
cores surrounded by coils of wire included in a circuit whereby currents of
alternately opposite direction are induced in said coils and flow upon the circuit
essentially as set forth;.
t

page_text: 2. The hereindescribed improvement in the art of generating induced currents
of electricity for telegraphic and other purposes, which consists.in alternately
magnetizing and demagnetizing a stationary body of iron within induction
proximity to magnetically polarized coils surrounded by coils of wire in circuit,
whereby reversed currents are set up in said coils and caused to traverse the circuit
essentially as set forth.
3. In an electric current generating and transmitting instrument the combination
with one or more pairs of magnetically polarized cores having opposing poles
adjacent to each other of coils of wire surrounding said cores and connected as
described and a stationary electro-magnet having a pole inductively adjacent to
but separated from the poles of each opposing pair of said cores substantially as
described.
4. In an electric current generating and transmitting apparatus the combination
of two permanent magnets arranged at a proper distance apart and having soft
iron pole pieces of opposite character projecting toward each other of coils of wire
surrounding said pole pieces and connected to give uniformity of direction to
currents resulting from, induction of opposite magnet cores, and a stationary
electro-magnet having its soft iron core or cores inductively adjacent to the poles
of each pair of opposed pole-pieces substantially as described.
5. In an electric current generating and transmitting instrument the combination
of the permanent magnets A A¹ having soft iron-pole pieces of opposite character
extending toward each other the coils surrounding said pole-pieces and connected
together as described and the stationary electro-magnet D, having the polar portions
of its cores inserted between and isolated from the opposing pole-pieces substantially
as described.
6. The combination in an inductive electric generator of two magnetically
polarized cones having poles adjacent to each other coils of wire surrounding said
cores and a stationary electro-magnet having a polar portion of its core inductively
adjacent to said cores substantially as described.
7. The combination with the magnetically polarized cores the surrounding
connected coils and the stationary electro-magnet with polar portions or a polar
portion adjacent to the poles of said cores of suitable means for causing an
intermittent flow of electricity through the coils of said electro magnet substantially
as described.
S. In a telegraphic receiving instrument the combination with a permanent and
an electro-magnet having its two cores similarly polarized by one of the poles of
said permanent magnet of an oscillating neutral armature having its opposite
ends arranged within attractive distance of the electro magnet cores respectively
substantially as described.
9. The combination with the permanent magnet, of the electro magnet having
its yoke piece in contact with one of the poles of said permanent magnet and the
oscillating neutral armature pivoted in front of the poles of said electro-magnet
substantially as described.
10. The combination, with the permanent magnet, the electro magnet having its
cores polarized by one of the poles of said permanent magnet and the neutral
armature pivoted to oscillate in front of the poles of said electro magnet of a
local circuit arranged to be closed and opened by said armature substantially as
described.