Improvements in Telephonic Transmission, and in the Art generally of Distributing or Transmitting Alternating Currents for Power and other Purposes.
Year: 1894

page_text: Date of Application, 2nd Jan., 1894-Accepted, 17th Feb.,
1894
COMPLETE SPECIFICATION.
Improvements in Telephonic Transmission, and in the Art generally
of Distributing or Transmitting Alternating Currents for Power
and other Purposes.
I, WILLIAM HAIN ECKERT, of 80 Broadway, in the City, County and State of
New York, United States of America, Electrical Engineer, 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 :-
My invention for the most part consists in the discovery that telephonic
transmission, or rapidly alternating currents in general, may be more perfectly
effected upon a bimetallic conductor, such as steel and copper in substantially equal
parts, than upon a conductor of one material, such as copper; and with the
advantage that such transmission may be effected upon a circuit consisting of a
single composite wire and an earth return as perfectly as though two copper wires,
each of equal conductivity, were arranged in a closed metallic circuit. In other
words, I find that a single bimetallic conductor joining two distant points is a more
perfect medium for telephonic transmission and for conveying generally rapidly
alternating currents than are two copper conductors, each of a resistance equal to
that of the bimetallic wire; and that from this fact the two conductors
necessary to form a single metallic circuit may be replaced by a single wire
costing little, if any, more than one-half of a copper metallic circuit.
I have also discovered that less insulation is needed to protect a bimetallic wire
than is necessary for copper or other single-substance conductors, in the trans-
mission of rapidly alternating currents, and that from this fact not only the expense
of constructing cables, whether aerial, underground or submarine, may be greatly
reduced, but more wire may be placed within a cable than could be done if the
usual thickness of insulation were used. Moreover, for the transmission of
alternating currents, wires of smaller conductivity, according to the ordinary
resistance measurements, may be used than is possible if they were constructed
of copper, iron or other single metal.
I am aware of what is popularly termed the "Ferranti effect" and that it has
long been known that in the mains of Ferranti's circuit potentials are higher at
a distance than at the source of generation; but notwithstanding prior knowledge
of this law or effect, I believe I am the first to point out the fact that
alternating transmissions are aided or made more perfect by the use of bimetallic
conductors.
"
The "Ferranti effect is associated with a circuit in which one main is placed
as an insulated wire within a conducting tube forming the return, and in this
respect the organization bears a remote resemblance to my bimetallic wire. The
difference, however, is obvious, and even if alternating transmissions by the
Ferranti cable are aided by such an organization it does not negative my right to
claim two dissimilar conductors in metallic contact with each other to form the
single conductor of a metallic circuit, or to form one branch of a circuit which is
completed by an earth return.
Either iron or steel may be used with copper, but steel is better adapted to
the purposes of bimetallic wire and its use in transmitting alternating currents
to great distances. Other dissimilar metals of essentially different specific
resistances may be used to advantage in transmitting alternating currents, but to
what extent their adoption would be beneficial I am unable to state. In comparing
my bimetallic conductor with those of a single substance I have pointed to the
fact that a single wire with an earth return may replace a metallic circuit of two

page_text: equally good copper conductors; but I do not intend to limit my use of bimetallic
wire to circuits having earth returns, as it is equally applicable to all other
arrangements of conductors upon which rapidly alternating currents are carried.
In the use of either steel or iron with copper, while the two metals should be
represented by approximately equal masses or cross-sections, there may be an
excess either of copper or iron, and particularly of the latter for telephonic
transmission, without materially departing from the advantages of a bimetallic
conductor for carrying such currents.
In the accompanying drawings
Fig. 1 represents a telephone system in which receiving and transmitting instru-
ments are joined by a bimetallic conductor.
Fig. 2 represents an alternating-current dynamo and an electric-light system
which is fed through bimetallic conductors.
Fig. 3 shows a bimetallic wire consisting of an iron or steel core and a copper
coating.
Fig. 4 shows a like bimetallic wire having an insulating covering, I.
My improved method or art may be practiced independently of particular forms
of apparatus, but, as an illustration, I have shown an arrangement in which my
invention is present in Fig. 1 of the drawings, consisting of a telephonic system
with_transmitting and receiving instruments at two distant stations, joined by a
metallic wire a, shown in Fig. 3 as having an iron or steel core b, upon which is
superposed a copper covering c. Another instance is represented in Fig. 2, in which
a similar bimetallic conductor, shown in Fig. 4, having a steel or iron core b, a
copper coating c, and an insulating covering d, is used for conveying the pulses of
an alternating generator m to a distance for light, heat or power.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. The improved art or method of transmitting telephonic messages, which
consists in developing a series of alternating electrical pulses representing said
messages, and in transmitting said alternating pulses over a conductor of bimetallic
wire consisting of iron or steel combined with copper or other dissimilar metals
of specifically different resistances, as and for the purpose set forth.
2. The improved art or method of transmitting electric currents to a distance,
which consists in the generation or development of a series of rapidly alternating
electrical pulses and in the transmission of said pulses over a bimetallic conductor
consisting of dissimilar metals, as and for the purpose set forth.
3. The improved art or method of transmitting electric currents to a distance,
which consists in generating a series of rapidly alternating electric pulses, and in
the transmission of said pulses over a bimetallic conductor consisting of iron or
steel combined with copper, as and for the purpose set forth.
4. The improved art or method of transmitting electrical pulses to a distance
and of isolating them from neighbouring objects, which consists in generating a
series of rapidly alternating currents, and in the transmission of such pulses over
a bimetallic conductor consisting of dissimilar metals, covered with an insulating
coating, as and for the purpose set forth.
Dated this 2nd day of January 1894.
ALLISON BROS.,
Agents for the Applicant.