IMPROVEMENTS IN DYNAMO-ELECTRIC TELEGRAPHY
Year: 1880

page_text: LETTERS PATENT to Sydney Pitt, of Sutton, in the County of Surrey,
for an Invention of "IMPROVEMENTS IN DYNAMO-ELECTRIC TELEGRAPHY."
A communication from abroad by Orazio Lugo, M.D., of the City, County,
and State of New York, United States of America.
COMPLETE SPECIFICATION filed by the said Sydney Pitt at the Office of the
Commissioners of Patents on the 21st December 1880.
SYDNEY PITT, of Sutton, in the County of Surrey. "IMPROVEMENTS IN DYNAMO-
ELECTRIC TELEGRAPHY." A communication from abroad by Orazio Lago, M.D., of
the City, County, and State of New York, United States of America.
The Invention relates to that class of electric telegraphs in which dynamo-
electricity is employed for the transmission of signals, instead of voltaic electricity
generated by chemical action.
In the application of dynamo-electric generators to the production of electric
currents for telegraphic transmission certain difficulties have been encountered,
arising from the presence of conditions which do not exist in the various forms
of voltaic batteries which have heretofore usually been employed as sources of
electrical power. In the case of the chemical batteries employed for telegraphy,
the resistance of the circuit or circuits exterior to the battery is very con-
siderable, while the electro-motive force remains practically constant, thus
producing a working current of uniform strength in the circuit or circuits
connected with the battery. In the case of dynamo-electric generators in which
the reaction principle is employed, the introduction into the circuit of a high
external resistance consisting of telegraph lines, which are alternately broken and
closed at irregular and arbitrary intervals for signalling purposes, produces wide
variations in the resistance, and subjects them to great variations in the electro-
motive force, which variations are due to changes in the intensity of the magnetic
field within which the currents have their origin. Furthermore, changes take
place within the machine or generator itself, arising from the increase of the
internal resistance by the heating of the wires and other causes.
The variations referred to are also attended by changes in the amount of power

page_text: required to drive the machine, and in the speed of rotation of the latter, which
changes again react upon the strength of the current generated.
It has been determined by experiment that the most efficient arrangement of a
dynamo-electric generator, that is to say, the one which produces the greatest
useful effect with a given expenditure of power, is that known as the single-current
machine, in which the coils of wire surrounding the stationary electro-magnets
which maintain the magnetic field and the external resistance are all included in
the same circuit.
In the attempts which have hitherto been made to operate telegraphic circuits
by means of dynamo-electric generators, it has been considered impracticable to
make use of the single-current machines, in consequence of the difficulties herein-
before stated, and resort has been had to the class of generators known as
double-current machines, in which the armature is wound with two wires, one of
these being connected in the circuit with the field-magnets, and the other with the
exterior circuit in which the work is to be done, or else two separate generators
have been coupled together, one being a single current machine, whose function it
is to polarize its own field magnets, and also those of the other generator, while the
armature of the latter supplies the current to the exterior circuit.
The Invention is designed to overcome the objections which have hitherto
prevented the employment of the more efficient, simple, and economical single-
current machine for telegraphic purposes, and to produce therefrom uniform and
constant currents over one or many telegraph lines of similar or varying lengths,
which are operated by alternately breaking and closing the circuit in the usual
manner.
The object of the first part of the Invention is to enable uniform currents to be
produced in telegraphic circuits by means of a single current dynamo-generator,
and to utilize these currents for the transmission of intelligible signals, which end
is attained by connecting the opposite poles of the generator by a shunt wire, or
short or branch circuit; and also by including said poles in the telegraphic circuit
of the main line, which is connected in multiple arc with the shunt wire, the field
magnets of the generator being kept charged through the intervention of the
constant current traversing the shunt-wire, and the proportion of such current
necessary to produce signals being thrown upon or diverted to the line by the
signalling apparatus, the resistance of the branch or short circuit being greater
than that of the generator, and less than that of the main line or lines.
The object of the second part of the Invention is to vary the electro-motive force
of the generator according to the work to be performed, which end is attained by
combining with a shunted or short-circuited generator a telegraphic circuit or
circuits, and signalling keys placed in multiple arc with said shunt-wire.
The law of operation of an apparatus thus organized is that as the number of
lines thrown into circuit is increased, the total resistance of the circuit exterior to
the generator is correspondingly diminished, and the electro-motive force of the
generator correlatively increased, or vice versa.
The object of the third part of the Invention is to enable intelligible signals to
be transmitted through all the telegraphic circuits connected with a dynamo
electric machine, by means of a single key or circuit-breaker, and to enable said
signals to be received simultaneously upon one or more receiving instruments
included in each circuit, which end is attained by alternately closing and breaking
the exterior circuit of said generator at a point traversed by the common current
of all the telegraphic circuits, but not by that of the shunt circuit connecting the
opposite poles of the generator.
The special object of the fourth part of the Invention is so to organize a
dynamo-electric generator in a telegraphic circuit, that a constant circuit may be
inaintained through the coils of the armature and field magnets of the generator, so
as to keep them continuously and sufficiently polarized, whether the exterior
working or telegraphic circuit be closed or open, which end I attain by combining
a telegraphic circuit, a dynamo-electric generator (the revolving armature and

page_text: stationary field-magnet of which are included in said telegraphic circuit), and a
shunt circuit of low resistance, connecting the opposite poles of the generator with
each other, the resistance of the shunt circuit being greater than the internal
resistance of the generator, but less than that of the exterior working or telegraphic
circuit.
The object of the fifth part of the Invention is to maintain a proper relation
between the resistance of the shunt connecting the opposite poles of a dynamo-
electric generator, and the resistance of the exterior or working circuit, which end
is attained by providing suitable means for increasing or diminishing the resistance
of said shunt circuit.
The object of the sixth part of the Invention is to enable one or more telegraphic
lines, which are operated in the usual manner by the opening and closing of a
key or keys to be thus operated in the exterior circuit of a dynamo-electric
generator, without interfering with the maintenance of the field of force in
said generator, which end is attained by combining with the said lines, keys,
and generator, a constantly closed shunt of low resistance connecting the opposite
poles of the said generator, the resistance of the shunt being greater than the
internal resistance of the generator, but less than that of the telegraphic circuit.
The object of the seventh part of the Invention is to maintain the proper relation
between the joint resistance of two or any required number of telegraphic lines,
which constitute the exterior circuit of a dynamo-electric generator, and the
resistance of the shunt circuit which connects the opposite poles of said generator,
which end is attained by combining with said lines, generator, and constantly
closed shunt circuit connecting the poles of said generator, suitable means for
increasing or diminishing the resistance of said shunt circuit.
The object of the eighth part of the Invention is to maintain a proper relation
between the resistance of the exterior or working circuit, when composed of two or
more telegraph lines, and the resistance of the dynamo-electric generator, and of
the shunt circuit connecting the opposite poles thereof, which end is attained by
providing means for increasing and decreasing the resistance of the several
telegraph lines, which constitute the exterior or working circuit.
The object of the ninth part of the Invention is to enable a proper relation to
be maintained between the internal resistance of a dynamo electric generator, the
resistance of the telegraph line or lines constituting the exterior or working
circuit, and the resistance of the shunt-circuit connecting the opposite poles of the
said generator, which end is attained by providing means for increasing and
decreasing the resistance of both the said shunt and the several lines which
constitute the exterior circuit.
The essential elements of the improved organization, shown in Figure 1, are
a dynamo-electric machine or generator of any of the well known and improved
forms of construction, a shunt-wire or short-circuit connecting the opposite poles
of the armatures thereof, an electric or telegraphic circuit or circuits connected
with the poles of said armatures, signalling apparatus of well known construction
in said circuit, and a local sounder in a branch circuit separate from the main line
and shunt wire.
The details of the apparatus shown, as well as the arrangement of such apparatus
with reference to the circuits, may however be modified in various ways without
departing from the principle of the Invention. In this instance three stations are
shown, a main or central station X and two terminal stations Y and Z.
The organization shown is well adapted for lines of ordinary length; for long
circuits however it would be preferable to place a generator at each end of the
line, taking care that their respective unlike poles are presented to the line. The
running of the circuits under the improved system is substantially the same as
that used where voltaic or chemical batteries are employed, that is to say, the
proper relative polarities of the apparatus must be maintained throughout. The
instruments of a large number of stations under this organization may be operated
from a single generator.

page_text: In Figure 1, A represents a dynamo-electric generator, which may be of any
suitable well known construction and driven by a power in the usual manner.
The opposite poles N, P, of the generator are connected by a shunt wire B in
which an adjustable rheostat or resistance coil R, h, is included. This adjustability
is for the purpose of giving the shunt the proper resistance relatively to the
generator. As an example of the proper relative resistance between the generator and
shunt, a resistance in the latter of from five to six ohms. is sufficient for a generator
having an electro-motive force or generative capacity of fifty volts., such an apparatus
being adapted to operate a line of from 500 to 600 miles in length, besides
supplying the necessary branch circuits or derived currents to operate the local
sounders. The rheostat could obviously be dispensed with by experimentally
adjusting the shunt wire to the proper relative resistance; as another extreme
example, with an electro motive force derived from a machine of low intensity
with a capacity of one volt., a resistance in the shunt of about one-thousandth of
an ohm. is required.
.
Telegraphic circuits or line wires 1, 2, 3, 4, and 5 are shown as connected with
the poles N, P, of the generator in the ordinary way of running branch telegraphic
circuits, those delineated in the Drawing being known as ordinary normally closed
earth-circuits, included in which circuits are ordinary telegraph keys K, K¹, K2, K³,
relays R, R¹, R², R³, sounders S, S¹, S², S³, adjustable rheostats R, h, being included
in the line wire wherever required to equalize the resistance of the circuits.
Under the organization shown the south pole P is the positive pole. Starting
from the ground G at the home or central station X a telegraphic circuit is shown
as running through the wire 4, key K², relay R², generator A at P, through the
field magnets and armatures of the generator to the binding-post of the pole N,
which post forms a common branching point for all the lines, any one of which
may be followed, for instance, through the line 4 and main line L to the station Z,
where it passes through relay R³ and key K³ to the ground G2, which is the ground
of opposite polarity of that from which the circuit started.
A local sounder S2 at the central station X is located in a local metallic circuit 3
starting again from a connection with the south pole P of the generator, running
through the tongue 2 of the relay R2 and through its contacts to the helix s² of
the sounder S2, thence through a rheostat R, h, to the point 3 on the north side of
the generator, and through the machine to its starting point. The corresponding
sounder S at the terminal station Z is also in a local metallic circuit b starting
from the south pole P of the generator A', running through the line b, helix s³ of a
local sounder S³, contact point and tongue ³, and line b to the north pole N of the
generator A at that station, and through the generator to the starting point.
This generator is also provided with a shunt or short circuit b¹ connecting its poles.
Under this organization it will be observed that the receiving instrument at
station Z is actuated by an independent generator included in its local circuit.
This plan of including the sounder at the terminal station in a local metallic
circuit provided with an independent generator is preferable for very long distances,
although the plan shown for working the locals by branch-circuit from the main
generator answers very well for circuits of ordinary length.
I will now proceed to describe the circuit connections between the home station
X and station Y, which are as follows:-Starting from the same ground G as
before, the circuit passes through the wire 4, key K2, and relay R2, to the south
pole P of the generator, thence through the generator to the north pole N, thence
out of the line 1, through relay R and key K to the line L', relay R¹, and key K¹
to the ground G¹ at that station. The corresponding local sounder at the home
station is included in a closed metallic circuit, starting from the south pole of the
generator through the machine, through the line 2, the tongue r of the relay R,
its contact point, and the helix s of the sounder S back to the starting point. The
local sounder at the terminal station Y is operated by a separate line-wire or
telegraphic circuit 5, the connections of which are as follows:-
Starting from the common ground G, through the wire 4, key K², relay R²,

page_text: through the generator and wire 5 to the tongue r¹ of the relay R¹, thence through
its contact point and helix s¹ of the sounder S¹ to a separate ground g.
In case it is desired to cut out the key K, its relay R2, and sounder S2, the
switch T is turned so as to connect the wire 6 with the generator without
disturbing their circuit connections, the effect of which is to ground the line at
the point g' instead of at the common ground G, thus shunting the key K² and its
ground.
The organization shown is that of a normally closed earth circuit through which
the current constantly flows, but an open circuit may be used if preferred. When
used as a closed circuit no current passes through the line as long as the keys
remain open, but the circuit passes through the generator and shunt. The resistance
of the shunt being greater than that of the internal resistance of the machine the
shunt wire becomes hot while the machine remains cool, an incidental advantage of
much importance as is well understood.
When a transmitting key is closed a portion of the charge from the machine
passes over the main line, the effect of which is to increase the electro motive force
of the generator, thus automatically and correlatively adapting the electro motive
force of the machine to the work to be done.
Experience has demonstrated that an apparatus organized as above described
affords a smooth regular current, by means of which signals may be transmitted
with great efficiency.
Under the organization of apparatus shown the working of the key K operates
the receiving instrument at station Y only, but when the switch T is open and the
key K2 is worked it operates not only its own receiving instrument and the
corresponding instrument S at the home station, but also the receivers at both
the terminal stations Y and Z.
In the diagram the switch T at station X is shown as open, but this does not
break the continuity of the circuit from the key K2 through the point 4 to the
south pole P of the generator. When the switch T is closed it connects the
generator through line 6 to ground, which closing, shunts or short circuits said key
without breaking its circuit.
In the accompanying Drawing Figure 2 is a diagram of a dynamo-electric
machine illustrating the application of the Invention thereto, and Figure 3 is a
diagram illustrating the application of the Invention to the operation of a number
of telegraph lines.
The essential elements of this part of the improved organization are a single
current dynamo electric machine or generator of any of the well known and
improved forms of construction; a shunt wire or short-circuit connecting its
opposite poles, an electric or telegraphic circuit or circuits connected with the poles
of said armatures and signalling apparatus of well known construction. Referring
to Figure 2, A represents a dynamo electric generator, which may be of any suitable
The
or well known construction, and driven by power in the usual manner.
generator which I prefer to use has its component parts arranged upon the principle
shown in the diagram, in which a is a revolving armature (enveloped in coils of
wire) which moves within the magnetic field of the stationary or field magnets
a', a¹. The positive and negative poles of the generator are at p and n respec-
tively, and the circuit through the machine or generator is as follows:-Com-
mencing at the positive pole p it passes by the wire 2 to the coils of one of the
field magnets a', thence by wire 3 to the commutator spring d', thence through
the coils of the rotating armature a, thence by commutator spring d and wire 4
to the other field magnet a¹, and thence by wire 5 to the negative pole n.
Now if the generator be set in motion no effect is produced until the opposite
poles p and n of the generator are connected by a conductor, as indicated by the
dotted line B; but as soon as this is done a weak current is excited in the coils of
the armature a, which also traverses the field magnets a¹, a¹, and the conductor B
which is termed the exterior circuit. The current excites magnetism in the cores
of the field magnets, which reacts upon the armature, and this action and reaction

page_text: continues until the cores reach their maximum of magnetism; or the attraction
between the revolving and stationary parts of the generator reduces the speed of
the armature, and an equilibrium is established between the mechanical resistance
produced by the attraction and the power which drives the machine, after which
the current developed will remain practically uniform so long as the resistance of
the exterior circuit B remains unchanged. If the circuit B is broken the field
magnets and armature are instantly discharged, and the maximum power can only
be regained by a series of actions and reactions after the circuit has been restored,
as hereinbefore set forth.
If the poles p and n of the generator be connected by a second conductor C,
technically termed a shunt-circuit, the resistance of the portion of the circuit
exterior to the generator will be diminished, and for that reason a greater quantity
of electricity will be produced, and, moreover, under this arrangement if the
conductor B is broken or disconnected the current through the field magnets and
armature will still be maintained through the shunt C, so that the generator will
continue to act, though with somewhat diminished effect.
In order to produce the greatest useful effect in the operation of a dynamo electric
generator two conditions must be observed:-First, the resistance of a portion of
the circuit without the machine must be approximately equal to that within the
machine, and, second, the resistance exterior to the machine must be kept practically
constant. The manner in which the conditions are fulfilled in the application of a
dynamo electric generator to the working of a number of telegraphic circuits of
various lengths and resistances will now be explained.
Referring now to Figure 3, A represents the dynamo-electric generator, having
its armature coils a and field magnets a', a¹, connected together in the same circuit,
as herein before set forth. The exterior or working circuit consists of the wire
which connects the positive pole p of the generator A with the earth at E (and
which together with the earth itself forms a conductor of no appreciable resistance),
the wire 6 also of no appreciable resistance, and three telegraphic circuits L, L',
and I, which branch from the wire 6 at the negative pole of said generator, and
terminate the first two in the earth at e and e¹ respectively, and the third in the
wire at the positive pole. These three circuits which, taken collectively, form
essentially the whole of the exterior or working circuit, are of very different lengths,
and consequently their normal resistances vary in like proportion. The exterior
resistance therefore is represented by the joint resistance of the three circuits, which,
by a well known law, is much less than that of any one of them individually.
The telegraph lines L and L' are each provided with transmitting keys K, k,
K, k, for alternately breaking and closing the circuit in order to transmit
intelligible signals, and also with suitable receiving instruments I, i, and I¹, ¹, these
being placed at different stations as shown. The line l, l, represents a local circuit
of small resistance, which is employed to actuate a sounder or other like instrument S
through the intervention of the instrument I' which is shown as a relay.
The shunt circuit C, C, connects the positive and negative poles p and n of the
generator A, as already explained, and it, in effect, forms a branch of the exterior
circuit.
It has already been stated that the greatest useful effect is produced when the
resistance of the interior and exterior circuits of the generator are approximately
equal. Now the joint resistance of the three working circuits or lines L, L³, and Z
is necessarily much greater than that of the generator itself, consequently the
resistance of the shunt circuit C should bear a certain relation to that of the
working circuits, and also to that of the generator, being necessarily less than the
former and greater than the latter.
The resistance of the exterior circuit is subject to change, inasmuch as a greater
or less number of lines may be required to be worked from it at different times,
while the resistance of the generator itself is practically constant. In order
therefore to maintain the proper relation between the resistances of different
portions of the systems, it is desirable to render the resistance of the shunt circuit

page_text: adjustable, which may be done by varying its length or otherwise. It is preferred
to use for this purpose a rheostat R (see Figure 2), which is composed of a
metallic bar M divided into sections, which are normally connected by metallic
Coils
pegs, but may be separated by withdrawal of any one of the pegs as at m.
of wire of graduated lengths as w, w³, w², w³, are connected from one section to
another of the bar M. Thus the withdrawal of the peg m as in Figure 2 adds the
length and resistance of the wire w to the shunt circuit, and in like manner any
of the shorter lengths may be inserted or withdrawn at pleasure. It is obvious any
required scope of adjustment in the length and resistance of the wire C, C, may be
obtained in this manner.
Where the difference in the length and resistance of the different lines is very
great, as, for example, the line L, which may offer a resistance of several thousand
units, and the local circuit l, which may offer not more than ten similar units, the
current will tend to divide itself very unequally, and by far the greater portion of
the total current will tend to traverse the shorter lines. This effect is objectionable,
not merely by reason of an excessive waste of current, and consequently of power,
but also because the breaking and closing of the shorter circuits produces con-
siderable variation in the total resistance of the exterior circuit, which for reasons
herein before given it is desirable to avoid. I therefore insert adjustable rheostats
or resistances in all the shorter circuits, as at r and r, which are constructed in
the same manner as the rheostat R already described. By this means the
resistances of the shorter lines may be so increased that the joint resistance of the
exterior or working circuit will be very great compared with that of the generator
and its shunt, by which another important advantage is secured, in that the system
becomes automatically self-regulating. The current required for operating even &
large number of lines of considerable resistance is far within the capacity of the
generator to supply. If, in closing and breaking the several circuits by means of
the keys, a considerable number of the lines should happen to be opened simul-
taneously, the resistance of the external circuit becomes greater, and consequently
the current through the field magnets is weakened, and the electro motive force of
the generator correspondingly decreased, while the opposite effect follows if all the
lines are closed, and more current required. Thus by placing adjustable rheostats
in all the branches of the exterior circuit, except the one having the greatest
resistance, the proper relations of resistance between the working circuits, the
shunt circuit, and the generator may be preserved at all times.
I also remark that as the shunt circuit C, C, must always be of a resistance
exceeding the internal resistance of the generator, but less than the resistance of
the telegraphic circuits, that the heat developed in the circuit will appear in the
shunt circuit, and not within the generator, an incidental advantage of much
importance; as the machine remains cold its internal resistance therefore continues
constant, and the current derived therefrom is consequently uniform.
It is often important to be able to transmit the same intelligence simultaneously
over a great number or over all the circuits radiating from a central station, as in
the distribution of press news and the like. By means of the organization shown
I am able to accomplish this result with great convenience simply by inserting a
transmitting key K² at a point in the exterior circuit of the several telegraph lines,
as L and L', but not in the circuit of the shunt wire C. It is obvious that by
manipulating this key the signals will be received on all the instruments I, i, I², i¹,
in the circuit of several telegraph lines.
The essential elements of the improved organization, shown at Figure 4, are a
dynamo electric machine or generator, a shunt wire or short circuit connecting the
opposite poles of the armatures thereof, the resistance of which shunt wire is
greater than the internal resistance of the machine, a transmitting key in the
primary circuit of an induction coil, and suitable signalling apparatus in a tele-
graphic circuit, including the secondary wire of said induction coil.
In the accompanying Drawing Figure 4 represents a diagram of the improved
apparatus organised in the best way now known to me.

page_text: The improvement contemplates the employment of the most approved apparatus
of the present day. The details of construction of such apparatus however are
well known, and need not therefore be herein described, as the construction and
arrangement of the apparatus may be modified in various ways without departing
from the principle of the Invention. I prefer to employ under this system a
generator at each station, but any number of instruments at such station may be
operated from the same generator.
The diagram represents three stations, a central one X, and two terminal stations
Y, Z. The organization of apparatus of each station being substantially similar, a
description of one will be sufficient, the arrangement of the two sets of transmitting
apparatus at the central station requiring nothing beyond the mere skill of the
workman in running the circuits properly.
Each dynamo-electric machine or generator A, A1, A2, is shown as having the
opposite poles N, P, of its armatures connected by a shunt wire B, B1, B³, the
resistance of which shunt wire is greater than the internal resistance of the machine,
but less than that of the telegraphic circuit or circuits. Each station is provided
with one or more transmitting keys K, K1, K2, K³, each included in the primary
metallic circuit of an induction coil, in branch circuit with the shunt of the
generator, that is to say, including the opposite poles of the armature in its circuit.
The secondary wire of these induction coils I, I, I, I³, and relays R, R¹, R³, R³,
are included in the main line L, which is an ordinary earth circuit. The primary
circuits may be kept either normally open or closed as preferred.
The sounder S, S¹, S2, S3, of each relay might be worked with a local battery in
the ordinary way, but I prefer to charge it directly from the main generator, which
I do by including it in an independent branch circuit D, d, D', d¹, which circuit
starting from one pole of the generator passes through the armature r, 1, 3, ³, of
each relay, and through the helix of the sounder back to the other pole of the
generator.
I will now describe the circuit connections between the home station and one of
the terminal stations. The arrangement under the organization shown being
duplicated for each station, a description of one will be sufficient for the proper
understanding of the other.
The transmitting key K at the sending station X is included in a primary closed
metallic circuit starting from the south pole P of the generator A at 3, and running
through the wire 3, key K, the primary helix i of the induction coil I, and the
wire 3 again, back to the north pole of the generator, and through the generator
to the starting point at 3.
The makes and breaks in the primary current caused by key K in this circuit
are reproduced upon the helix i of the induction coil I, which is included in the
line wire. The latter is what is known as an earth circuit starting from the ground
at G, passing through the secondary helix of the induction coil I, thence through
the relay R, line wire L, relay R¹, and the secondary helix of the induction
coil I at station Y, to the ground at G .The sounder S at the sending station X is
always included in a metallic circuit, passing through the point 2 connected with
the south pole of the generator, through the wire D, the helix of the sounder S, the 4
contact point and tongue r of the relay and wire D, back through the point 2 to
the north pole N of the generator, thence through the generator to the starting
point. The organization at the receiving station is substantially the same, and the
parts are similarly lettered.
Under this organization it will be seen that the sounder is in branch circuit with 5
the shunt-wire and transmitting key, and that while the tongue or armature of the
sounder is controlled by the primary circuit from the generator, its circuit is made
or broken by the vibrations of the tongue or armature of the relay, which is
actuated by the secondary current of the line wire.
The operation of the apparatus will readily be understood from the foregoing 5
description.
When the transmitting key is closed, a portion of the charge of the machine

page_text: passes through the primary circuit, the makes and breaks in which circuit induce
corresponding impulses in the secondary circuit in a well known way, and vibrate
the tongues of the relays, the effect of which is to open and close the circuit of the
Bounders, causing them to respond correspondingly.
I claim :-
First. As an improvement in the art of dynamo electric telegraphy, the method
herein before described of producing intelligible signals in a telegraphic circuit by
generating dynamo electric currents in branch circuit with the main line, the
resistance of the branch circuit being greater than that of the generator, and less
than that of the main line or lines.
Second. As an improvement in the art of dynamo electric telegraphy, the method
hereinbefore described of automatically varying the electro motive force of the
generator by merely throwing the line wire into or out of circuit..
Third. The combination, substantially as hereinbefore set forth, of a dynamo electric
generator, a constantly closed shunt circuit, and one or more telegraphic circuits, all
connected in multiple arc with said generator, one or more instruments for receiving
intelligible signals included in each of said telegraphic circuits, and a key or circuit
breaker placed in the exterior circuit of the generator at a point traversed by the
common current of all the telegraphic circuits, but not by that of the shunt
circuit.
Fourth. The combination, substantially as hereinbefore set forth, of a telegraphic
circuit, the revolving armature coil and stationary field magnet of a dynamo
electric generator included in said circuit, and a shunt circuit of low resistance
connecting the opposite poles of the generator, the resistance of said circuit being
greater than the internal resistance of the machine, but less than that of the
telegraphic circuit.
Fifth. The combination, substantially as herein before set forth, in a dynamo
electric generator, of a revolving armature coil, and a stationary field magnet, both
of which are included in the same circuit with the exterior resistance, a shunt-
circuit which connects the poles of the generator with each other, and thereby acts
to keep the circuit of the armature and field-magnet continuously closed without
reference to the condition of the exterior or working circuit, and means for adjusting
or regulating the electrical resistance of said shunt circuit.
Sixth. The combination, substantially as herein before set forth, of a dynamo
electric generator, one or more electric circuits connected therewith, one or more
keys for transmitting signals through said circuit or circuits by alternately breaking
and closing the same, and a constantly closed shunt circuit of low resistance
connecting the opposite poles of the said generator, the resistance of the shunt
circuit being greater than the internal resistance of the generator, but less than
that of the telegraphic circuit.
Seventh. The combination, substantially as herein before set forth, of a dynamo
electric generator, one or more electric circuits connected therewith, one or more
keys for transmitting signals through said circuit or circuits by alternately
breaking and closing the same, a constantly closed shunt circuit connecting the
opposite poles of the said generator, and means for adjusting or regulating the
electrical resistance of said shunt-circuit.
Eighth. The combination, substantially as herein before set forth, of a dynamo
electric generator, one or more electric circuits connected therewith, one or more
keys for transmitting signals through said circuit or circuits by alternately
breaking and closing the same, means for adjusting or regulating the resistance of
said circuit or circuits, and a constantly closed shunt circuit connecting the opposite
poles of the said generator.
or
Ninth. The combination, substantially as herein before set forth, of a dynamo
electric generator, one or
more electric circuits connected therewith, onc
more keys for transmitting signals through said circuits by alternately breaking
and closing the same, means for adjusting or regulating the resistance of said
circuit or circuits, a constantly closed shunt circuit connecting the opposite poles of

page_text: said generator, and means for adjusting or regulating the electrical resistance of
said shunt circuit.
Tenth. The combination, substantially as herein set forth, of a dynamo electric
machine or generator, a constantly closed shunt circuit connecting its opposite
poles, one or more telegraphic circuits included in branch circuit with the generator,
apparatus for producing intelligible signals on the line, and a local sounder in
branch circuit with the shunt circuit and telegraphic circuits.
Eleventh. The combination, substantially as herein set forth, of a dynamo-electric
machine or generator, a shunt wire or short circuit connecting the opposite poles of
its armatures, a primary circuit (in which is included a key and the primary helix
of an induction coil) in branch circuit with said shunt wire, with a telegraphic
circuit or main line in which are included the secondary helix of the induction
coil, and signalling instruments actuated by the currents induced in the secondary
circuit by the makes and breaks of the primary.
In witness whereof, I, the said Sydney Pitt, have hereunto set my hand and
seal, this Sixteenth day of December, in the year of our Lord One thousand
eight hundred and eighty.
SYDNEY PITT. (L.S.)