Improvements in Induction Telephone Repeaters.
Year: 1886

page_text: Date of Application, 9th June, 1886
Complete Left, 8th Mar., 1887.
Complete Accepted, 7th Apr., 1887.
PROVISIONAL SPECIFICATION.
Improvements in Induction Telephone Repeaters.
I SIDNEY FORTESCUE SHELBOURNE of 11 Gold Street in the City of New York
and State of New York, United States of America, counselar at law, do hereby
declare the nature of my Invention for IMPROVEMENTS IN INDUCTION TELEPHONE
REPEATERS to be as follows:-
The object sought to be attained by this invention is that telephonic speech may be
transmitted or repeated from local single or grounded circuits between a subscriber
and his adjacent exchange upon and over a metallic circuit between said exchange and
any other similar exchange and thence again from said metallic circuit upon and over
a single or grounded circuit to a subscriber locally connected with the second exchange
and vice versa, thus enabling a working telephonic system to be composed of a com-
bination of many local single circuits employing the switch boards now in general use
at the exchanges with trunk lines between the exchanges, constructed in metallic
loops in underground cables, thereby avoiding the expense of metallic circuits between
the several exchanges and their relative subscribers and also the labor and expense of
making double connections at each call of a subscriber, or as an alternative making
radical alterations in the switch board systems of the exchanges.
Attempts have been made with ordinary induction coils to accomplish this object
but with indifferent success, such coils not being equally reciprocal in inductive effect
as between the primary and secondary of the same coil, i.e, outwardly and inwardly,
nor reciprocal when two coils, one at each end of a metallic circuit are joined in that
circuit through the secondaries of both, so that the sender on a ground circuit at one
end is transmitting by induction outwardly while the receiver on a similar ground
circuit at the other end has to take the sound by induction from the secondary of
the coil at his end of the line into the primary connected in his own ground circuit.
To overcome the difficulties hitherto encountered and greatly improve the reciprocal
inductive effect the present invention consists in a novel construction of the induction
coils by the employment of two magnetic cores, or any number of pairs of cores,
in the same instrument. These cores are alike composed of a bundle of soft iron wires
and each of them forms the longitudinal axis, within a cylinder of paper or equivalent

page_text: material, of a spool with a head of wood or similar non-metallic substance at each end
of the wire bundle. The two spools are wound exactly alike with two small sized
silk covered copper wires of substantially the same gauge length and resistance, both
together as one, in parallel circuit, to and fro, upon each of the spools until a sufficient
fullness or depth of winding has been obtained. If but one pair of cores or spools is
to be used to compose an induction repeater, the two spools, after being wound, are
placed upright, on end, upon a suitable base of ebonite or similar material, having an
oval plate of soft iron fitted upon its upper surface equal in general area to the
combined heads of the two spools when placed side by side upon it.
The ends of the spools resting upon the base are made to cover the soft iron plate
which is overlaid with an insulating material, so as not to be in metallic contact with
the iron wire bundles of the axes of the spools. The spools are so placed above the
soft-iron plate of the base that (when the silk covered wires of the one are connected
with those of the other, and a current is passed through either one of the two circuits
extending, when joined together, around both of the spools, and composing two
parallel and correlated circuits) the north pole of the core of the one is adjacent,
upon the plate, to the south pole of the core of the other, and, of course, the upper
ends of the cores will be related to each other in a similar manner.
The two ends of each of the silk covered wires composing the two parallel circuits,
are led respectively to two binding posts at each side or end of the ebonite base.
A soft iron oval case is fitted around the spools so as to snugly enclose them, side by
side, the lower open end of this case corresponding in area to that of the soft iron plate
fitted to the ebonite base, while the upper end of said case has an oval cover of soft
iron fitted upon it so as to come very near to the upper ends of the two magnetic
cores or wire bundles and yet not so as to be in metallic contact with them.
A small brass rod passes down through this cover and between the heads of the
spools (which are slightly cut away to allow room for it) and down through the ebonite
base, and by means of a thread and nut at each end of it, serves to bind the parts of
the instrument firmly together.
The arrangement of the circuits and the soft iron parts of the instrument in
manner as described has been found in practice to give a greatly increased inductive
effect over that produced by single cores, besides the circuits in the repeater as herein
designated are equally reciprocal either in giving or receiving the currents of
induction.
Daiad : 571
T

page_text: COMPLETE SPECIFICATION.
Improvements in Induction Telephone Repeaters.
I SIDNEY FORTESCUE SHELBOURNE of 11 Gold Street in the City of New York
and State of New York United States of America, counselar at law do hereby declare
the nature of my invention for IMPROVEMENTS IN INDUCTION TELEPHONE REPEATERS
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:–
The object sought to be attained by this invention is to repeat in a more distinct
and perfect manner than heretofore, speech telephonically from local ground circuits
onto and over trunk line metallic circuits and thence again onto and over local ground
circuits at the stations where the message or speech is delivered and vice versa, thus
enabling vocal communication to be carried on over a combination of ground circuits
with metallic circuits, between persons located on the ground circuits and many miles
separated from each other.
Various attempts have been made with ordinary induction coils to accomplish this
object but with indifferent and unsatisfactory results, such coils not being mutually
and equally reciprocal in inductive action as between the primary and secondary of
the same coil-i.e, outwardly and inwardly-nor reciprocal when two coils, one at
cach end of a metallic circuit are joined in that circuit through the secondaries of
both, so that the sender on a ground circuit at one end is transmitting by induction
outwardly while the receiver on a similar ground circuit at the other end has to take
the sound by induction from the secondary of the coil at his end of the line into the
primary connected in his own ground circuit.
To overcome the difficulties hitherto encountered and greatly improve the reciprocal
inductive effect, the present invention consists in a novel construction of the induction
coils, by the employment of two magnetic cores or any number of pairs of such cores
in the same instrument. These cores are alike composed of a bundle of soft iron
wires and each of them forms the longitudinal axis, within a cylinder of paper or
equivalent material, of a spool with a head of wood or similar non-metallic substance
at each end of the wire bundle. The spools are wound exactly alike with two small
sized silk covered copper wires of substantially the same guage length and resistance,
both together as one, in parallel circuit, to and fro, upon each of the spools until a
sufficient fullness or depth of winding has been obtained. If but one pair of cores or
spools is to be used to compose an induction repeater, the two spools, after having
been wound, are placed upright on end, upon a suitable base of ebonite or similar
material, having an oval plate of soft iron fitted upon its upper surface equal in general
area to the combined heads of the two spools when placed side by side upon it. The
ends of the spools resting upon the base are made to cover the soft iron plate which is
usually overlaid with an insulating material so as not to be in direct metallic contact
with the iron wire bundles of the axes of the spools or the soft iron rods in the
longitudinal centres of those axes; but an equally desirable effect will be produced if
the said soft iron bundles or their soft iron binding rods are actually placed in metallic
contact with the soft iron plates, or if the heads of the spools themselves are made of

page_text: soft iron and placed in contact with each other across their diameters, thus dispensing
with the use of the soft iron plates, the object being to afford an easy or a complete
magnetic circuit produced in the pair of cores in combination with each other by soft
iron plates or soft iron spool heads (in contact with each other) at both ends of the
pairs of magnetic cores.
The spools are so placed upon the soft iron plate of the base that (when the silk
covered wires of the one are connected with those of the other, and a current is passed
through either one of the two circuits extending when joined together around both of
the spools and composing two parallel and correlated circuits) the north pole of the
core of the one is adjacent upon the plate, to the south pole of the core of the other,
and, of course, the upper ends of the cores will be related to each other in a similar
manner.
The two ends of each of the silk covered wires composing the two parallel circuits
are led respectively to two binding posts at each side or end of the ebonite base.
A soft iron oval case is fitted around the spools so as to snugly enclose them side by
side, the lower open end of this case corresponding in area to that of the soft iron
plate fitted to the cbonite base, while the upper end of said case has an oval cover of
soft iron fitted upon it so as to come very near to or in contact with the upper ends of
the iron wire magnetic cores or their axial soft iron binding rods in the approach to
or in the completion of a magnetic circuit between the pair of cores as already
described.
A small brass rod is passed down through the cover of the instrument and between
the heads of the spools (which are slightly cut away to allow room for it) and down
through the ebonite base. This brass rod having a thread cut on each of its ends and
fitted with nuts above and below serves to bind the parts of the instrument firmly
together.
The figures of the drawing forming a part of this specification will serve to illustrate
the several features of the invention. Fig. 1 shows a vertical section of the instrument
taken through the line ar, y, Fig. 4. In said Fig. 1, A and B represent the two
magnetic cores, E, E, the soft iron case enclosing the spools, g, g, the soft iron binding
rods of the spools respectively, and c, c, the small brass rod with nuts at either end
securing the parts of the instrument together. Fig. 2, shows a view diagrammatically
of the relation of the two parallel circuits and their windings with respect to the
magnetic cores and their connection with the binding posts of the base of the
instrument. Fig. 3 is a plan view of the separation of thic ends of the two wires
composing the parallel circuits and their respective listribution to the binding posts;
thus, binding post 1 and 2 will represent the extremities of one of the wires, a, and
binding posts 3 and 4 will likewise represent the extremities of the wire b, as shown in
Fig. 2. Fig. 4 presents an elevation in perspective of the instrument as a whole,
when its parts are joined together.
The two spools, each having its own magnetic core, as shown, with the soft iron
plates or end pieces or heads in contact to facilitate or complete the magnetic circuits,
enables a given length of the wires to be wound closer to the magnetic cores of the
spools and the mutual inter-action of the magnetic forces created in each of the spools
gives the wires mutually a greater sympathetic relation with each other by reason of
the increased intensity of the magnetic field in which they are situated because of
the disposition of the parts as shown. Thus the arrangement of the circuits and cores
and end plates or heads in manner as described has been found in practice to give a
greatly increased inductive effect between the circuits under the influence of inter-
rupted or variable currents over that produced by single cores. Moreover, it is
obvious that the inductive effects between the parallel circuits in relation as herein
described are equally and mutually reciprocal.
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 combination of two or more separate magnetic cores and their surrounding
coils in parallel circuits of two insulated wires, wound as one, said parts being in such

page_text: relation that the opposite polarities of the cores of each pair shall be at their adjacent
ends, as described in the foregoing specification.
2. Two parallel circuits of substantially equal length and resistance in identical
correlation with each other about two or more independent magnetic cores, forming
induction giving and receiving circuits (each to or from the other) as herein
described.
3. Two or more soft iron wire bundles or cores, each within its separate coil of
magnet wire, arranged in pairs, each pair having the opposite polarities of its members
adjacent at the ends, in combination with soft iron plates or heads extending across
the poles of such pair, as and for the purpose set forth.
4. Two spools formed each with a magnet core, and each wound with two insulated
wires of substantially equal length and resistance and in parallel circuit with cach
other upon both spools, being wound thereon in such a manner that the contained
magnetic cores shall have opposite polarities at their adjacent ends, in combination
with soft iron polar plates or heads and an inclosing case or box of magnetic material
substantially as shown and described.