IMPROVEMENTS IN ELECTRIC CIRCUITS
Year: 1881

page_text: LETTERS PATENT to Sydney Pitt, of Sutton, in the County of Surrey, for
an Invention of "IMPROVEMENTS IN ELECTRIC CIRCUITS." 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 31st May 1881.
"IMPROVEMENTS IN
SYDNEY PITT, of Sutton, in the County of Surrey.
ELECTRIC CIRCUITS." A. communication from abroad by Orazio Lugo, M.D., of
the City, County, and State of New York, United States of America.
In Letters Patent granted to me, dated March 15th, 1881, No. 1119, I have
shown and described an electric telegraphic and telephonic conductor constructed
in the form of a solenoid. This solenoid is shown as, consisting of a direct insulated
conductor passing longitudinally through the mathematical axis of a helical
conductor or conductors also insulated.
The present Invention is based upon the Invention heretofore referred to and
constitutes an improvement thereon. It consists in a novel organization of the
conductors constituting said circuit, whereby the interferences arising from action
and reaction upon each other of derived or induced currents and the retardation
and prolongation of signals arising therefrom are more perfectly prevented.
The subject matter claimed is specifically designated in the claims at the end of
this Specification.
When a direct and a return conductor are combined together in the form of a
single solenoid it is obvious that the total length and resistance of the conductor
which constitutes the helical portion of the solenoid will be much greater than
that of the portion forming the axial conductor. This inequality in the resistance
of the two parts of the circuit is objectionable. These are, as stated in the former
Specification, two methods of construction whereby this difficulty is diminished or
avoided. The first consists in making the helical conductor of a thicker wire than
the axial conductor, and consequently of less resistance per unit of length, but this
construction may be found objectionable for mechanical reasons. The second
method consists in forming the helical conductor of two or more equal wires laid
parallel to each other in a spiral around the axial conductor, and afterwards

page_text: joining their extremities in multiple arc, so that they constitute in effect a single
conductor. This construction is not open to the mechanical objections incident to
the first method, but on the other hand it may involve increased complexity,
greater cost of construction, and greater liability to injury.
In both these methods of construction, moreover, there exists a certain degree of
inductive action and reaction between the currents flowing in opposite directions
through the direct and the return conductor. This is, however, so small as to be
inappreciable except upon circuits of considerable length; it is due to the fact that
the helical conductor of a solenoid from the nature of the case cannot be placed
perpendicular to the axial conductor but must be more or less inclined thereto.
Now, it is well known that the greatest inductive reaction between two conductors
takes place when they are parallel to each other, and that no inductive reaction
whatever can take place between two conductors at right angles to each other.
The amount of this inductive reaction is in all cases in proportion to the cosine of
the angle between the conductors.
The present Invention is designed to overcome the objections herein before
referred to, and it consists, speaking generally, in forming the direct and return
conductors into a compound solenoid consisting of two or more simple solenoids
joined together in series and cross-connected at their junctions. I am thus enabled
to construct a conducting circuit in which the total resistance of the direct and
return conductor is substantially the same, while at the same time they may be
constructed of wire of similar thickness. Certain other advantages in the
conduction of the currents also arise in connection with the organization, which
advantages will be hereinafter more fully set forth.
In the accompanying Drawings Figure 1 represents a portion of a conducting
circuit embodying these improvements.
Figure 2 illustrates the manner in which the same may be arranged for use with
the ordinary telegraphic instruments.
Figure 3 shows the same as adapted for use in connection with speaking
telephones.
Figure 4 shows the manner in which this Invention may be applied to circuits
employed for electric lighting.
Figure 5 shows an application of the same circuit for conveying or transferring
electric power.
Figure 6 is a cross section of one form of a submarine or subterranean cable
containing three independent circuits embodying the Invention, and which may be
used for either or all the purposes hereinbefore mentioned.
The organization of this improved conductor will be best understood by reference
to Figure 1, in which one conductor, which may be considered as the direct
conductor, is shown at A, A, and the other or return conductor at B, B, the two
conductors being assumed to be united at their opposite ends so as to form a
complete electric circuit. Each conductor is enveloped in an insulating coating of
gutta percha, or other suitable dielectric a, a, and b, b. The direct and return
conductors together form a number of solenoids, as shown at C, D, E, and F, which
solenoids are united together at their ends so as to form a continuous series. For
example, the solenoid C is formed by coiling the insulated conductor B closely into
a helix surrounding the insulated conductor A; hence A is in this instance the
axial and B the helical conductor. In the next solenoid of the series, as shown
at D, this arrangement is reversed in consequence of the manner in which the
conductors are interchanged or cross connected, B now becoming the axial conductor
and A. the helical conductor. The next solenoid E in the series is arranged in the
same manner as C, and in like manner F is similar to D. Thus it is to be
understood that the entire circuit, whatever may be its length, is formed of a series
of solenoids joined together in the manner described, the axial conductor of each
solenoid being joined to the helical conductor of its neighbour on each side, and
vice versa. The direction in which the electric currents flow through the
conductors A and B are indicated by the arrows in Figure 1. These several

page_text: elementary solenoids, which are afterwards joined together to form the complete
conductor as described, may be of any convenient length. In practice it will be
ordinarily be found advantageous to construct them of the length in which it is
practically convenient to manufacture insulated wires before joining them up into
a long cable. It is preferable that the several solenoids of the series be of
substantially equal length.
Some of the advantages which result from the improved organization of
conductors which I have described may be enumerated as follows:-
First. The axes of the two conductors are coincident throughout the length of
the circuit, and hence the mean distance of each conductor from all surrounding
objects of whatever nature must necessarily be the same. It follows from this
that any inductive disturbance which tends to be set up in any surrounding object
by the influence of the direct current traversing one conductor will be effectually
counteracted by the influence of the return current traversing the other conductor
in the opposite direction, and thus no inductive charge can be produced to react on
the conductors; second, the two conductors may conveniently be made of the same
thickness and of the same resistance per unit of their respective lengths; third, the
total resistance of the direct and the return conductor between one terminal station
and the other are substantially equal; fourth, the inductive actions and reactions
which tend to manifest themselves between the direct and the return currents in
consequence of the greater or less approach to parallelism between the helical and
the axial conductors are neutralized and eliminated.
All so called insulating substances possess in some degree the property of
conducting electric currents. Even gutta-percha, which is ordinarily employed for
the insulating coating of submarine conductors, is capable of conducting electricity
to an extent which may be definitely measured, although that resistance is
enormously great in comparison with that of the conductor which it encloses. It
follows from this fact that when an electric current is transmitted through a con-
ducting wire coated with gutta-percha, and surrounded by a conductor such as
water, or the earth, or the armour of a cable, that a portion of the current flows
directly through the mass of insulating coating to the water or other external
conducting medium. When such a current begins to flow through the insulating
coating it gradually and rapidly diminishes in strength as if the resistance of the
dielectric increased under the influence of the current. This apparent increase in
resistance however is not caused by an actual resistance, for when the original
current ceases the dielectric or insulating coating sends back into the conductor a
gradually decreasing current in the opposite direction, and this current is of such
magnitude and lasts for such a time as to return to the conductor that portion of
the electricity which had at first apparently flowed through the dielectric in excess
of the quantity which would have passed in the same time through a constant
resistance equal to the final resistance. The effects of this action is to retard the
discharge of the electricity from the cable at the termination of each signal, for
during the transmission of the current required to produce a signal at the distant
station the dielectric becomes charged by absorption in the manner hereinbefore
stated, and after the current has ceased it sends back most of the electricity which
has been thus absorbed, and thus maintains an extra current in the conductor
after the proper termination of the signal, which tends to obliterate the interval
between the said signal and the next succeeding one.
It will be observed that whatever may be the effect which is produced upon or
within the dielectric surrounding the conductor by a current in one of the
elementary solenoids of which the conductor is made up, equal and opposite effects
will necessarily be produced upon the surrounding dielectric by the current in the
next adjacent solenoid of the series, hence if the dielectric be continuous, as in the
case of the insulating coating of a submarine or subterranean telegraph, these
effects of the currents will necessarily tend to neutralize instead of reinforcing each
other, and causing their several effects to accumulate as the length of the circuit is
increased. It follows from this that any reaction on the part of the dielectric

page_text: upon the current traversing the insulated conductor will also be of an opposite
character in each alternate section, and these several actions will in like manner
tend to neutralize each other and not to accumulate.
In Figure 2 I have shown the improved conductor as applied to an ordinary
commercial telegraph circuit, being provided at its terminals with suitable
batteries E and E', and having a key K, a receiving instrument R at one terminal
station, a key K¹ and a receiving instrument R¹ at an intermediate or way station,
and a key K2 and a receiving instrument R2 at the remaining terminal station. It
is preferred to arrange the apparatus at the intermediate station in the manner
shown in the Figure, the key being in the direct circuit and the sounder in the
return circuit, or vice versa. Figure 3 shows a series of receiving and transmitting
telephones for the transmission of articulate and other sounds, the arrangement of
which is the same in principle, T, T¹, and T being the telephonic transmitters,
and t, t¹, and t the telephonic receivers; Figure 4 represents the application of
the Invention to an electric circuit for the purpose of electric illumination;
G represents the dynamo-electric generator, the positive pole of which is attached
to the direct conductor and the negative pole to the return conductor, and this
arrangement may be reversed, the particular arrangement in this respect being
immaterial. The said generator has its opposite poles united by a shunt conductor s
with an adjustable rheostat 1 inserted therein in the manner and for the purpose
more fully set forth in my former Letters Patent, No. 1119, dated March 15th, 1881,
to which reference is had. I have shown two electric lamps L and L', which may
be of any suitable construction, and may be arranged either in series or in multiple
arc, which is the plan represented in the Drawing, the lamp L being placed in a
cross connection between the direct and the return conductor, as shown in the
Drawing. I have represented this lamp as being placed between the two solenoids.
Figure 5 represents a dynamo electric machine arranged in the same manner in
connection with the improved circuit for the transmission of mechanical power to
a distance; the remote terminals of the direct and the return conductor are con-
nected as shown to the terminals of an electro-magnet engine or motor M. The
cross section in Figure 6 represents three of the improved conductors organized in
the manner illustrated in Figure 1, which are embodied in a cylindrical mass of
non-conducting material and enclosed within an armoured or other protecting
envelope W; these several conductors may be used for any or all of the purposes
hereinbefore set forth.
I claim,―
First. The electric conductor hereinbefore set forth, consisting of two or more
solenoids connected together in series as described, and having the helical conductor
of each solenoid joined to the axial conductor of the next solenoid in series in each
direction, and vice versa.
Second. The electric conductor hereinbefore set forth, consisting of a series of
solenoids in which each terminal of the series has one end of its axial conductor
joined to its own helical conductor, and the other end to the helical conductor of
the next solenoid in the series.
Third. An electric circuit, consisting of a direct and a return conductor in the
form of a compound solenoid constructed in the manner hereinbefore set forth, so
that each conductor becomes alternately the helical and axial conductor thereof.
In witness whereof, I, the said Sydney Pitt, have hereunto set my hand
and seal, this Twenty eighth day of May, in the year of our Lord One
thousand eight hundred and eighty one.