Year: 1899

page_text: Date of Application, 11th Aug., 1899-Accepted, 28th Apr., 1900
I, FREDERICK BEDELL, of No. 4, Cook Street, Ithaca, County of Tompkins,
State of New York, United States of America, Scientist, 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:—
Figs. 1-6 illustrate diagrammatically certain forms of my invention;
Figs. 7-12 illustrate different wave forms which the current impulses may
assume;
Fig. 13 illustrates a form of apparatus which may be employed to carry out my
invention, and .
Figs. 14 and 15 represent modified features which may be employed in con-
nection with such apparatus;
F.gs. 16 and 17 illustrate an elementary form of generating apparatus ;
Fig. 18 is a diagram of the transmitted current impulses;
Figs. 19-21 illustrate forms of generating apparatus;
Fig. 22 is a diagram of both negative and positive impulses;
Figs. 23-27 illustrate apparatus for the transmission of such negative and
positive impulses.
My invention relates to a method of transmitting direct currents in a series
of impulses for use for telegraphic purposes. the system being especially adapted
for the transmission either by land line or submarine cable of telegraphic currents
in which the succeeding impulses are combined and modified in a predetermined
manner so as to send intelligible messages according to a specified code.
In the art of telegraphy it has heretofore been common to transmit positive
and negative impulses over a circuit so combined as to afford a means of communi-
cation in conformity with a prescribed code. It has also been proposed to iransmit
a series of alternating current-impulses of a uniform. frequency and to interrupt
the alternating current thus introduced into the circuit at the zero points in
accordance with a prearranged code.
In neither one of the two methods just mentioned am I aware that it has been
attempted to adapt the wave form of the current-impulse to meet circuit con-
ditions, nor to employ a continuously and gradually varying current in order to
avoid the inductive disturbances which sudden current variations will produce;
while in the second method of the two the interruption at the zero point has here-
tofore occurred at the moment of the greatest self-induction when the current-wave
s changing from positive to negative, or vice versa, at the highest rate, the curve of
electro-motive force being comparatively steep on either side of the zero line.
It is the object of my invention to provide a system of transmitting current-
mpulses, by means of which the current may be interrupted at the zero periods,
and in which the impulses may be prolonged to any desired degree, and in which
lso the form of the wave may have when desired a long graduated zero space
luring which it may be broken at a period of minimum self-induction and con-
equently with the minimum spark at the contact.

page_text: I provide in my system any desirable source of direct current and derive there-
from a series of direct current impulses by including and excluding in a cyclic
order a set of graduating resistances which may severally have any desired value,
which may even be changed or varied from time to time so that the succeeding
impulses may have a corresponding wave form, and particularly may come when
desired to a graduated zero, so that at the zero point the circuit may be broken
with the least unfavourable effects due to inductive and electro-static disturbances.
I also provide an apparatus by which, while the current impulses are transmitted
in an invariable sequence, it is yet possible at desired points to maintain a con-
nection from a source of direct current to the line from the crest of one impulse
wave to that of the next or other succeeding wave, and thereby in effect multiply
the normal wave length by two, three or any desired number.
I further provide a method for generating dynamically unidirectional currents,
(as distinguished from alternating currents,) which are derived from a suitable
generator and vary in a cyclic order from zero to maximum so as to take the form
of a series of direct current impulses which may be interrupted at the zero point
in any desired manner for the transmission of intelligence by the combination
of the impulses according to a pre-arranged code.
I have also invented a method of securing.impulse currents by a combination
of direct and alternating electro-motive forces which give in combination a vari
able current suitable for the telegraphic system above mentioned.
Referring to Fig. 1 of the drawing, let A represent a battery or any other con-
venient source of direct current which is to be transmitted over a circuit formed
An ordinary
by the line wires B and C to act upon a receiving apparatus D.
rheostat or adjustable resistance R is shown as included in the circuit in series
with the receiver D). It will be evident that, if the movable contact E of the
rheostat R were caused to reciprocate back and forth over the series of contact
plates of the rheostat R, a succession of current-impulses would be transmitted
over the circuit corresponding to the movement of the contact E and the varia-
tion between minimum and maximum in the amount of resistance thereby in-
cluded in the circuit.
The basis of my invention is the transmission, by means of any suitable ap-
paratus, of current-impulses such as would result from the arrangement illustrated
in Fig. 1; by giving special values to the several sections of rheostat R, impulses
having any required wave form may be secured at will.
Turning to Fig. 2 of the drawing, I have there shown the contact plates or
rheostat R arranged in a semi circle and connected respectively to similar plates
forming the complimentary semi circle. The contact E is shown as a radial arm
journaled concentrically with the series of plates and sweeping over them as
it rotates, being driven by any suitable mechanism such as a belt F from a pulley G
which in turn may be driven by an electric motor or any other agency having a
uniform rate of movement. This arrangement will give the same result as would
and illustrates one method
be secured by the reciprocation of contact E in Fig.
of securing a succession of impulses by a continued rotary movement of the
transmitter.
Referring to Fig. 3, the rheostat R is shown as shunting both the battery A
and the receiver D) and it is evident that in this manner also there will be a
series of impulses transmitted to the circuit by the reciprocation of the contact E
of the rheostat R. a short circuit being prevented by the resistance R* in the line
from the battery as shown.
In Fig. 4 there is the same arrangement which appears in Fig. 3 except that
the contact E is arranged for rotary instead of reciprocating movement. Again,
as indicated in Fig. 5, the rheostat R is partly in series and partly in shunt with
the receiver D and in Fig. 6 the same arrangement is shown with the provision
of a rotary instead of a reciprocating contact E: while I have also shown a second
set of rheostat sections R¹ connected to the right hand half of the circular series
of contact plates so that the rising current wave may be differentiated from the

page_text: falling wave, as shown in Figs. 11 and 12, by inserting one series of rheostat
sections and withdrawing another series.
The essential feature of this part of my system is the provision of a series of
contact plates of varying potential and to attain this end 1 do not limit myself
to any particular means. In one form of my invention the described resistances
may consist of a number of primary or secondary cells which may be used as
the original source of energy or may be connected to an outside source of
electricity, being thus used as resistances in the manner described to obtain the
desired values of potential of the succession contact plates.
In general I desire it to be understood that I do not intend to limit myself in
regard to the particular means employed for transmitting the rheostatically-
graduated impulses over the circuit, but may employ any suitable means for
securing that result.
Referring to Fig. 7, there is shown therein a curve of impressed electromotive-
force impulses which appears as a succession of triangles, this being the form
which would result from a complete uniformity in the series of rheostat sections
and a uniform reciprocation of the contact E. If, however, the sections at and near
the two extremities of the series have a smaller value than the others, the angles
of the curve shown in Fig. 7 will be rounded off, as shown in Fig. 8, and by the
same means the curve may be further modified to the form shown in Fig. 9. By
the employment of different sets of rheostat sections for the rising and falling
parts of the wave respectively as shown in Fig. 6 it may be made to assume the
form shown in Fig. 11 or even that-shown in Fig. 12.
For utilizing electric current of the form I have described in the transmission
of telegraphic messages I may employ any suitable circuit-breaker arranged to
interrupt the circuit at the zero points of the current according to a determined
code. Thus I may employ the well known form of transmitter consisting of a
perforated tape running over a metallic cylinder so as to pass under a brush
normally bearing upon such a cylinder and thus interrupt the connection between
the brush and cylinder except where the perforations may occur in the tape. The
tape will be fed synchronously with the rotation of the contact E described above
and the perforations will be so spaced as to interrupt the circuit at such points
of zero current as may be necessitated by the requirements of the code and the
message which is being sent.
I prefer, however, to add to a simple apparatus of this kind a second row of
perforations in the tape which will control a second contact spring or brush
arranged to short-circuit or otherwise eliminate the effect of the impulse-con-
trolling resistance above described. By this means I may so arrange the second
row of perforations in the tape as to practically suppress, at desired points and
for desired periods, the modifying effect of the said resistances upon the current
and thereby prolong to any desired extent any current impulse or impulses in
the series employed for the transmitted message, the wave then being somewhat
as appears in Fig. 10.
Referring to Fig.13, H represents a tape, such as I have described, passing over
a metallic cylinder J and having therein two rows of perforations, while two con-
tact springs K and L bear on the cylinder above the tape in line with the
respective rows of perforations. The cylinder J forms the terminal of line B
while the contact spring K is connected to contact E and the spring L is connected
directly to negative terminal of battery A whose positive terminal is connected
to line C.
Obviously the connections may be reversed, the positive battery terminal being
connected to spring L and the negative to the line. If the spring K were per-
manently in contact with the cylinder the line would be closed and the con-
tinued operation of the contact E would transmit in the manner already described
in connection with Figs. 5 and 6 a series of impulses of a uniform character, such
as is indicated at Fig. 13, but such impulses would be modified or suppressed
in a definite manner by any series of perforations in the tape H which might pass

page_text: under the spring K, such perforations being timed and spaced so that the unper-
forated parts of the tape will come under spring K at the instant when the current
is at its minimum or at zero. Thus considering only the spring K and the line
of perforations in the tape shown in the figure there would be (see Fig. 13b a
transmission of impulse 1, a suppression of impulse 2, a transmission of the
first half of impulse 3 and the last half of impulse 4, with a suppression of the
last half of impulse 3 and the first half of impulse 4 and so on, the suppression
corresponding to the unperforated part of the tape and the transmission to the
perforated part. Simultaneously, however, with the action of spring K there is
the action of the spring L connected directly to the terminal of battery A so as
to connect the battery directly to line when bearing upon its own line of per-
forations in tape H. Therefore as shown in the figure, the suppressing effect of
spring K at the last half of impulse 3 and the first half of impulse 4 is neutralized
by the spring L which, at the same instant, comes over a perforation in the tape,
so as to continue the current flow which would have been interrupted by the
spring K if it alone were operating. Thus the effect of the spring L is to bridge
from the crest of impulse wave 3 to that of impulse wave 4 as is indicated by the
full lines in Fig. 1. In the same manner spring L comes in again to bridge
the impulse waves 9, 10 and 11.
Consequently the resultant effect will be a series of impulses having the form
shown by the full line curve of Fig. 13b. Thus there will be a normal impulse
followed by a zero space, then an impulse of twice the normal length, followed
again by a zero space, then two impulses of normal length, another space, then
an impulse of three times the normal length, then another space, and so on. The
method of bridging from the crest of one impulse to the crest of a following im-
pulse may likewise be employed when the impulses are generated dynamically
as hereinafter described.
I therefore have available as code-elements current impulses either of the
normal length or of any multiple thereof, together with zero spaces of any desired
length. With these available elements I can use a code that is very brief with
respect to the range of indication which it affords.
The same indicating value may be assigned to a long impulse as is assigned
to the several component impulses which would occur during the same period
if the impulse were not sustained by means of the brush L. In this case the
deleterious effects of self-induction that are inseparable from the multiplicity
of short impulses are avoided as mentioned above. This enables me to transmit
more rapidly than would be otherwise possible. In cases where the circuit con-
ditions permit a succession of single impulses, these may be employed as code
elements as well as the corresponding sustained impulses, a still greater rapidity
of transmission being thus made possible on account of the briefer code thereby
obtained.
In the foregoing description I have for simplicity shown an arrangement
wherein one complete revolution of the contact arm produces one cycle or impulse
of electricity from zero to full value and again to zero. It is commonly desirable,
however, to obtain more than one cycle or impulse from one revolution of the arm.
In Fig. 14 I have shown the resistance R as connected to four sets of contact
plates arranged in sequence around a circle so that a contact arm in sweeping
over them may introduce and withdraw the resistance four times at each rotation,
the plates being cross connected somewhat after the manner of a cross connected
commutator.
Instead of the form of resistance which I have shown, wherein the graduation
is secured by sections of resisting wire included in or excluded from the circuit
in succession, I may employ a resisting conductor and arrange the contact arm
to sweep over it from end to end so as to give a finer graduation. Thus in Fig. 15
R represents an inlaid ring of carbon set into a block K of insulating material.
The carbon ring may have an irregular cross section so that its resistance may

page_text: have any desired value at different points of its length. The arm E will sweep
over the carbon ring and thereby include in or exclude the resistance from the
circuit in the manner already described.
It will be understood that in using the expression graduated resistance I intend
to include such graduation as would be accorded by the apparatus illustrated in
Fig. 15, and that the cyclic series of impulses I have described is not limited
to a succession of impulses that are uniform in period, value or wave form since
these may be modified, as I have shown, to make up a code for the transmission
of communications.
Although in many cases I desire for the reasons set forth to produce the re-
quired current impulses by means of a graduated resistance as described, I prefer
in certain cases to generate such impulses dynamically, for which purpose I
employ the apparatus hereinafter described.
In Figs. 16 and 17 a generator is shown of a type sometimes known as a
"unipolar" machine which produces without commutation a current which is
always in the same direction. In this machine A is a field magnet, whose opposite
poles N and S embrace, upon one side of its axis, an armature consisting of a
series of radial arms or spokes C, C, etc., which are electrically united by a common
hub at their inner extremities and at their outer extremities are connected re-
spectively to the centres of insulated sections of the rim. This armature may be
driven by a pulley P when, according to well known principles, a current will
be generated in the several arms CC in succession, which current will flow longi-
tudinally along the arm and may be taken off from the armature bearing forming
one terminal, and from a brush B bearing upon the periphery of the armature and
constituting the other terminal of the circuit. As each arm Centers the magnetic
field its corresponding peripheral section comes into contact with the brush B
and it begins to generate an electro-motive force which rises to a maximum in
a gradual manner and similarly decreases again to zero at the instant when its
peripheral section breaks contact with the brush B, the pole pieces N & S being
properly shaped to give this result. The same operation will be repeated by the
several arms in succession, so that for each rotation of the armature there will be
in the example illustrated eight current-impulses having the wave form illustrated
in Fig. 18.
It is well known that in unipolar machines there are various expedients for
securing a higher electromotive force than would be generated by a single length
of conductor passing through the magnetic field, such expedients ordinarily
involving the employment of a separate set of brushes for the individual con-
ductors cutting the magnetic field and the connection of such conductors in series
through the said brushes. I contemplate the employment of such expedients
and of such other expedients familiar to the art in connection with unipolar
machines, whenever it may be desirable to increase the available electromotive
force without affecting the general character of the current impulses.
In Fig. 19 I have shown another method of securing current impulses appro-
priate for my system. In this figure D is the commutator of an ordinary direct-
current generator of the Gramme or Siemens type, whose armature
supposed to
be constantly rotated in a constant magnetic field. Upon this commutator bears
a stationary brush. E connected to one terminal of the circuit, while the other
terminal of the circuit is connected to a rotating brush B. Each rotation of the
brush B will give one current impulse which will be at a maximum when the
brush B is diametrically opposite the brush A and at zero when it is in coinci-
dence therewith. The rate at which the impulses are generated will be dependent
of course upon the speed given to the rotating brush B.
In Fig. 20 I have shown another method of producing current impulses of the
desired character. In this figure F is a Gramme ring upon which there are
wound two equal and distinct circuits H and K, the former being shown in dotted
lines and having its diametrically opposite points connected respectively to the

page_text: collector rings F1 and F, and the latter shown in full lines and connected at
intervals to the several bars of commutator D upon which bear the brushes D¹
and 12. Thus an alternating current will be produced in one winding and a
direct current in the other and the two will be connected in series. Since both
windings have the same number of turns and rotate in the same magnetic field
they will generate the same electromotive force and, in combination, they will
give a series of unidirectional impulses, one for each rotation, which, at the
maximum point, will have twice the electromotive force of the respective wind-
ings and will then fall completely to zero, since the two electromotive forces of
the respective windings will when opposed cancel each other and will unite when
co-operating. Thus by combining equal alternating and direct electromotive
forces we have as a result a pulsating direct electromotive force which falls com-
pletely to zero.
Fig. 21 shows an arrangement for reaching the same result with a single
winding, which is connected as before to a commutator D and also has its diametri-
cally opposite points connected to collector rings F1 and F. The rotation of the
armature will thus generate both an alternating and a direct electromotive force,
the former appearing at the collector rings F 1 and the latter at the commutator
brushes DD. The alternating current is led to the primary coil of a trans-
former J whose secondary is in series with the direct current passing from the
brushes to the line. In this manner also may the alternating electromotive force
be imposed upon the direct to convert the latter into a pulsating electromotive
force touching the zero line between the succeeding impulses.
I desire in some cases to produce two such unidirectional pulsating currents
which are distinct from each other, one positive and the other negative but both
having common zero points, the two currents having the wave form shown in
Fig. 22.
Both currents can then by means of the transmitter be interrupted at
once by breaking the circuit when both are at zero and at any subsequent period
either a positive or a negative impulse may be selected for transmission. This
will increase greatly the code capacity of the system since for each impulse I
have the choice of either a positive or a negative current which is not possible
with an alternating current, nor, of course, with a single current only. Further-
more, on account of the graduated zero, the current is interrupted at the period
of minimum inductive effect, and consequently impulses may be transmitted over
land lines or cables at a much higher speed than can be attained with an alter-
nating current interrupted at the zero points at which times the current is chang-
ing most rapidly and the disturbing inductive effects are the greatest.
A result somewhat similar to the one which I attain has heretofore been atlained
by employing two alternating electromotive forces of opposite polarity, one
being positive when the other is negative and vice versa. In such a case, the
generated electromotive force being always alternating it is necessary in order
to impress on the line only positive or only negative impulses to alternately con-
nect first one and then the other source of alternating electromotive force to the
line by a circuit changing device operating between succeeding semi cycles, which
must produce either a momentary open or short circuit, with the disturbing
inductive effect incident thereto. In my arrangement, however, the circuit
remains closed except as it be opened or controlled by the transmitting device,
and it becomes possible to send a succession of impulses without opening the
circuit or short circuiting the line in the manner necessitated by the prior arrange-
ment just mentioned
Fig. 23 shows a method of generating and applying such double direct currents.
In this Figure 1) is the commutator of a direct current machine and besides the
two brushes D1 and D2 there is a third intermediate brush D³ half way between
the other two. This third brush, which may be termed the zero brush, is
connected to the transmitting line and the other two brushes D' and D2 are con-
nected respectively to one of the collector rings of two alternators for modifying

page_text: •
the uniform direct current into a pulsating direct current. The two rings of one
alternator are indicated at F1 and F (the latter being connected to brush D¹)
and those of the other at 13 and F (the former being connected to brush D2).
The rings F and F are connected respectively to the brushes M and N of the
transmitter which bear on the perforated tape T which has two rows of perfora-
tions, one under each brush, that allow the brushes to make contact with cylinder
K leading to the opposite line wire of the transmitting system whenever a per-
foration comes opposite a brush. By suitably perforating the tape, and adjusting
its speed with reference to the frequency of the impulses, either a positive or a
negative impulse complete from zero to zero may be transmitted, or both may be
suppressed for any desired period, by having the unperforated part of the paper
pass under the brushes M N at the instant of zero current. The positive impulses
may for example correspond to the dashes and the negative impulses to the dots
"
code would be trans-
of the Morse code, and, as appears in Fig. 25, the word
mitted by a series of impulses having the sequence indicated in the figure. Any
other desired combinations may be made on the same principle. The receiving
apparatus R may be of any well known description or of any form adapted to
respond to the transmitted impulses.
66
In Fig. 24 another method of generating the two sets of impulses from a single
winding is shown, being somewhat analagous to the arrangement of Fig. 21 in
combination with that of Fig. 23. Here the rings F1 F2 lead, as before, to the
primary circuit of transformer J, but there are two secondary coils, each in series
with one of the brushes 11 D and the corresponding line wire. Thus, just as
in Fig. 23, there is a positive and a negative unidirectional electromotive force,
both modified synchronously by an alternating electromotive force and converted
into the described pulsating electromotive force.
Still another method of securing the double unidirectional current with coinci-
dent maximum and zero points is indicated in Fig. 26 which shows an armature
having two similar windings independent of each other and each provided with
a commutator, upon which the brushes D1 and D2 bear in the usual manner, while
two connected rotating brushes D³ and D+ bear respectively upon the same two
commutators, this arrangement being, in some respects, a duplication of the
arrangement appearing in Fig. 19. The brushes D₁ and 12 lead respectively to
the brushes M and N of the transmitter shown in Fig. 8, while the two brushes D³
and D correspond to the intermediate or zero brush 13 of Fig. 23 and are in like
manner connected to the line. When the rotating brushes D3 and 14 are coinci-
dent in position with the stationary brushes D1 and D2 both currents will be at
zero, and at 180° will be at maximum, so that there will be a simultaneous
transmission of the double pulsating unidirectional currents in the manner already
described.
Still another arrangement is shown in Fig. 27 wherein as in Fig. 26 there are
two armature windings, each with a single stationary brush (D1 and D2), while
the zero brush D³ bears upon a collector ring connected to each of the armature
windings at a suitable point therein, being connected to the outer winding at
the point d and to the inner winding at the point d. The action of this form
of machine will be similar to that shown in Fig. 26 while the use of the rotating
brush is avoided by the presence of the collector ring.
It will be understood that in the several arrangements of generators above de-
scribed I may, in the well known manner, use multipolar instead of bipolar
machines, while in other respects I do not limit myself to the precise apparatus
shown but may adopt other modifications embodying the same general principles
without departing from the spirit of my invention.
I may for example use a rotary converter as the source of current. Thus in
Fig. 21 the chain-dotted lines show wires leading from any source of direct
current, as an electric lighting system and connecting with brushes D¹ and D³.
This will serve to drive the machine as a rotary converter which will produce the
telegraphic currents already described.

page_text: Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The method of transmitting, for telegraphic purposes, a cyclic series of
current-impulses over an electric circuit, which consists in applying thereto a
direct electromotive force and repeatedly modifying such applied electromotive
force by means of graduated resistances or cells or by an alternating. electromotive
force, and receiving the transmitted impulses by suitable receiving apparatus.
2. The method of transmitting currents of electricity, for telegraphic purposes,
which consists in generating dynamically one or more series of unidirectional
impulses of electromotive force which impulses successively fall to and rise from
zero, and receiving the transmitted impulses by suitable receiving apparatus.
3. The method of telegraphing which consists in transmitting over a circuit
a series of direct-current impulses, having a gradually rising and falling value
and of any desired wave form, but preferably having a minimum rate of change
at or near the zero points, or two such series of impulses of opposite polarity with
simultaneous maximum and zero points, interrupting the circuit at moments
of zero current according to a predetermined code, and receiving the transmitted
impulses by suitable receiving apparatus.
4. The method of telegraphing which consists in transmitting a cyclic series
of current-impulses over an electric circuit by repeatedly modifying the effect
upon the circuit of a source of direct current connected to such circuit by means of
resistances, cells, or an alternating electromotive force, interrupting the circuit
at moments of zero current according to a predetermined code, and receiving the
transmitted impulses by suitable receiving apparatus.
5. The method of telegraphing which consists in transmitting over a circuit
current-impulses having a gradually rising and falling value, combining impulses
of different lengths according to a predetermined code, preferably by prolonging
their maximum periods, and receiving the transmitted impulses by suitable
receiving apparatus.
6. A telegraphic receiving apparatus with a line circuit connected thereto
carrying currents of electricity derived from one or more series of impulses of
direct electromotive force having gradually rising and falling values and preferably
with a minimum rate of change at or near the zero point, said currents acting
upon the receiving apparatus intermittently according to a predetermined code.
7. The dynamic generating apparatus herein described whereby one or more
series of unidirectional impulses of electromotive force may be produced, as and
for the purposes described.
Dated this 10th day of August 1800
FELL & JAMES,
Agents for the Applicant.