IMPROVE- MENTS IN APPARATUS FOR AND ARRANGEMENTS OF TELEPHONIC EXCHANGES
Year: 1881

page_text: LETTERS PATENT to Charles Denton Abel, of No. 28, Southampton Buildings,
Chancery Lane, in the County of Middlesex, for an Invention of "IMPROVE-
MENTS IN APPARATUS FOR AND ARRANGEMENTS OF TELEPHONIC EXCHANGES."
A communication from abroad by La Société Generale des Telephones, of
Paris France
PROVISIONAL SPECIFICATION left by the said Charles Denton Abel at
the Office of the Commissioners of Patents on the 1st September 1881.
CHARLES DENTON ABEL, of No. 28, Southampton Buildings, Chancery Lane,
in the County of Middlesex. "IMPROVEMENTS IN APPARATUS FOR AND ARRANGE-
MENTS OF TELEPHONIC EXCHANGES." [A communication from abroad by La
Société Generale des Telephones, of Paris, France.]
This Invention relates to improved apparatus and arrangements for facilitating
the working of telephonic exchanges at the central stations.
According to the present Invention the telephonic circuits are composed of two
wires instead of a single wire and the earth as heretofore, both wires being united
in one and the same insulated covering, and seven sets of such double wires being
grouped together in one cable, which consequently serves for seven subscribers.
The groups of such cables passing from the underground conduits are led through
an underground branch passage to the building of the central station. From this
passage they pass into the building through a metal plate attached to the wall of
the building, which plate has as many separate holes as there are cables in the
group, whereby the cables are effectually separated from each other, and also the
passage of offensive smells into the building through the passage communicating
with the underground conduit is prevented. From this plate the cables are led
along channels to the " rosace or apparatus, by which the connections are
established between the conducting wires and the exchange apparatus, one half of
the cables being led to the bottom and the other half to the top of the rosace.
"
This rosace, which may have one, two, three, or more faces, consists of one or
more vertical plates or panels secured to uprights, and having a central circular hole..

page_text: The ends of the several cables are spread out at equal distances apart round this
hole, each cable being attached to a stud at some distance therefrom, whence the
seven pairs of wires composing it are spread out, each one being passed through one
of a series of holes situated at the outer periphery of a sector of the central part
of the panel. Beyond the said hole the pair of insulated wires are separated
from each other and attached to a disc bearing the name and address of the
subscriber to whom the wires belong, and from this disc the wires are led to two
contact screws on an ebonite plate, each of which screws is connected by a
conducting plate to another pair of contact screws to which are attached the two
ends of an insulated cable with two wires that lead to the commutator of the
subscriber. Each such cable carries a plate with the number of the subscriber and
of the table of the commutator: By this means it is rendered easy to group
together the cables on the rosaces in such a manner that at the commutators the
subscribers that communicate most often with each other have their "jack-knives".
nearest to each other, thereby greatly facilitating the work of the operator.
The said connecting cables are led to the edge of the before mentioned circular
hole of the rosace, where they are secured between caoutchouc blocks. They are
there collected together in groups of 25, this being the number of commutators to
each table, and these groups are led along channels behind the tables at the level
of the floor. There are two sets of vertical tables arranged back to back, the wires
being led between them, and each group of 25 is spread out upon the corresponding
table. Each table consists of the "announcers" at top, below which are the
"jack-knives" of the subscribers, and below these the connectors that serve to
establish the communications with the several tables.
The "jack-knife" for the two-wire system is formed by superposing two
jack knives" of ordinary construction; it consists of two plates insulated from each
other by ebonite and fixed by insulated bolts to the table. Below each plate is a
spring, each of which has two studs; the one stud of the one spring enters a hole
at the side of the one stopper hole in its plate so as to be in contact with its
stopper when inserted, while the other stud enters a side hole and is in contact
with one of the fixing bolts. The studs of the spring of the other plate enter
similar holes in the sides of the other stopper hole in such plate and hole of the
fixing screw.
The outer plate has two stopper holes of large diameter, and the inner plate has
two stopper holes of smaller diameter; one of these is formed in a plug separate
_from_the_plate_and_insulated therefrom by a cylinder of ebonite, but a screw is
provided that can establish a communication between the plate and the plug. In
like manner a screw can establish a communication between the other plate and
one of the fixing bolts. The stoppers consist of an ebonite handle through which
the wires of the flexible conductor connecting the two stoppers pass, the one wire
being connected to a split ring on the handle of a diameter corresponding to the
large stopper-holes, while the other wire is connected to a projecting split stem at
the end of the handle of a size to fit the small stopper holes.
The current from the subscribers wire enters by the outer plate and issues
by the inner plate. By this arrangement the relay or announcer may be put
in circuit or in a derivation circuit. In the latter case the arrangement remains
as described. In the "waiting" position the current enters the outer plate, passes
through the one fixing bolt, and thence through the conducting wire to the
announcer or relay, and through the conducting wire to the other fixing bolt, thence
through the stud of the spring in contact therewith and through the spring and
the inner plate. A "calling" current sent by a subscriber consequently passes to
the announcer, and the operator's attention is drawn thereto.
If the double stopper is inserted into the one pair of holes, the stud on the one
spring is acted upon so as to remove the other stud from the fixing bolt, and the
introduction of the stopper has the effect of establishing communication with the
calling subscriber. If a current be sent into the line (as for instance by the
subscriber when he has finished his conversation) it passes through the connecting

page_text: screw of the one fixing bolt, and so on to the relay or announcer and back through
the inner plate to the other wire.
If the stopper be put in the other pair of stopper holes it still establishes
communication with the subscriber; but as by this means the spring of the inner
plate is moved so as to break contact with the other fixing bolt the current cannot
pass between these two, and the relay or announcer is consequently no longer in a
derivation circuit. Thus when communication is established between two
subscribers by means of their "jack-knives," one of the stoppers of the connecting
wires is inserted in the one stopper hole of the one jack-knife, and the other stopper
is inserted in the opposite stopper hole of the other jack-knife, so that a single
announcer is in derivation circuit.
In order to put the announcer or relay in the circuit the connecting screws are
removed from the two plates and a branch wire is connected to the insulated plug
of the inner plate, as before stated. The subscribers are by preference connected in
groups of 25, and as far as possible those subscribers are grouped together that
communicate most often with each other. Assuming that there are two groups
of 25 in each table, and that there are 10 tables of 50 subscribers, or 500 subscribers
altogether, at a central station, the electric connections of the connectors of the
several tables would be as follows:-Those connectors bearing the same
letters A, B, C, D, E, F, in one and the same horizontal row are connected
together; it is arranged that the first row is to be devoted to the communications
of the subscribers of the first table with the others; that the second row corresponds
with the second table, and so on. For instance, if the subscriber No. 15 of the
first group of the first table demands communication with No. 87 of the second
group of the second table, then the operator having heard the call of No. 15
connects by the stopper-couple the jack-knife 15 with a connector of the first row,
say B. On the other hand, after having called No. 87, he connects the jack-knife
of the latter with the connector B of the first row, taking care to put the stoppers
in the jack-knives in different holes, so that only one announcer shall be in
circuit.
Conversely if it be a subscriber of the second table who desires communication,
the stoppers are put in the connectors of the second row.
The lower rows of the connectors serve for establishing communications
permanent, or otherwise, from one station to another.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Charles Denton Abel in the Great Seal Patent Office on the
1st March 1882.
CHARLES DENTON ABEL, of No. 28, Southampton Buildings, Chancery Lane,
in the County of Middlesex. "IMPROVEMENTS IN APPARATUS FOR AND ARRANGE-
MENTS OF TELEPHONIC EXCHANGES." A communication from abroad by La
Société Generale des Telephones, of Paris, France.
"
This Invention relates to improved apparatus and arrangements for facilitating
the working of telephonic exchanges at the central stations. According to the
present Invention the telephonic circuits are composed of two wires instead of a
single wire and the earth as heretofore, both wires being united in one and the same
insulating covering, and seven sets of such double wires being grouped together in
one cable, which consequently serves for seven subscribers. Figs. 1 and 2 of the
accompanying Drawings shew a vertical section and a plan of the complete system
of apparatus from the underground conduit to the tablets of the subscribers. The
groups of such cables a passing from the underground conduits are led through an
underground branch passage A to the building of the central station. From this
passage they pass into the building through a metal plate Cattached to the wall of the
building, which plate is shewn detached at Figs. 3 and 4. It has as many separate
holes b as there are cables in the group, whereby the cables are effectually separated
from each other, and also the passage of offensive smells into the building through
the passage communicating with the underground conduit is prevented. From this
plate the cables are led along channels D, D, to the "rosace' or apparatus by which
the connections are established between the conducting wires and the exchange
apparatus, one half of the cables being led to the bottom and the other half to the
top of the rosace. This rosace E, which may have one, two, three, or more faces,
but which on the Drawing is supposed to have two, consists of one or more vertical
plates or panels E secured to uprights c, and having a central circular hole. The
ends of the several cables a, a, a, are spread out at equal distances apart round this
hole, each cable being attached to a stud d at some distance therefrom, whence the
seven pairs of wires e, e, e, composing it are spread out, each being passed through
one of a series of holes f situated at the outer periphery of a sector F of the central
part of the panel, one of which is shewn to an enlarged scale at Fig. 5. Beyond
the said holes the pair of insulated wires g, g, are separated from each other, each
having its insulated covering, and attached to a disc h bearing the name and address
of the subscriber to whom the wires belong, and from this disc the wires are led to
two contact screws i, i, on an ebonite plate j, each of which screws ȧ is connected
by a conducting plate respectively to one of a pair of contact screws ¹, to which
are attached the two ends of an insulated cable with two wires that lead to the
commutator of the subscriber. Each such cable k carries a plate with the number
of the subscriber on the tablet of the commutator. By this means it is rendered
easy to group together the cables on the rosaces in such a manner that at the
commutators the subscribers that communicate most. often with each other have
their "jack-knives" nearest to each other, thereby greatly facilitating the work of
the operator. The said connecting cables are led to the edge of the before-
mentioned circular hole of the rosace, where they are secured between caoutchouc
blocks n, Fig. 5. They are there collected together in groups of 25, this being the
number of commutators to each table, and these groups are led along channels G,
Figs. 1 and 2, behind the tablets at the level of the floor. As shewn at Fig. 2,
there are two sets of vertical tablets arranged back to back, the wires being led

page_text: between them, and each group of 25 is spread out upon the corresponding tablet.
Fig. 6 shews a section of the two sets of tablets. Each tablet consists of the
announcers at I, below which at J are the "jack-knives" of the subscribers, and
below these at K the connectors that serve to establish the communications with
the several tablets.. The "jack-knife" for the two wire system, which is formed
by superposing two "jack-knives" of ordinary construction, is shewn in horizontal
section at Fig. 7. It consists of two plates M, M', shewn separately at Fig. 8,
insulated from each other by the ebonite N, and fixed by insulated bolts 0, 0, to
the tablet. Below these plates are arranged springs m, m³, each having a stud o
and o, and at opposite ends a point p, p. Furthermore a screw q' allows a com-
munication to be established between the plate M and the socket P, and the
screw q connects the plate M with the bolt O. In combination with the double
jack-knife is employed a double stopper, shewn in elevation at Fig. 9, and in
section at Fig. 10. It is formed of a split ring r on an ebonite handle, in the
centre of which is embedded the split stem 8. The two ends of the double
wire of the flexible cable are connected, one to the ring r and the other to the
stem 8.
The plate M has two holes t, t, the diameter of which corresponds with
that of the ring 7, and the plate M³ has two holes u, u', corresponding to the.
diameter of the central stem 8. The current from the line of the subscriber
enters by the outer plate M and issues by the inner plate M¹. With this arrange-
ment the relay or announcer R can be put either in derivation or in the circuit.
In the first case the system remains as it is. In the waiting position the current
enters by M, passes through screw q, bolt O, wire x, announcer or relay R, wire y,
bolt O', stem p', spring m³, and plate M¹. A calling current sent by a subscriber
therefore enters the announcer, and the operator's attention is drawn thereto.
If the double stopper is inserted into the one pair of holes t, u, the stud o on the
one spring m is acted upon so as to remove the point p from the fixing bolt,
and the introduction of the stopper has the effect of establishing communication
with the calling subscriber. If a current be sent into the line (as for instance
by the subscriber when he has finished his conversation) it passes through the
connecting screw q of the one fixing bolt O and wire to the relay or announcer
R, and back through the wire y, bolt O', stud p¹, spring m³, and inner plate M',
to the other wire. If the stopper be put in the other pair of stopper holes t', u',
it still establishes communication with the subscriber, a current sent by whom
enters at M, passes to the screw q, wire x, relay R, and wire y; but as by these
means the spring of the inner plate is moved so as to cause o' and p¹ to break
contact with the other fixing bolt, the current cannot pass between these, and the
relay or announcer is consequently no longer in a derivation circuit. Thus when com-
munication is established between two subscribers by means of their "jack-knives'
one of the stoppers of the connecting wires is inserted in the one stopper hole t of
the one "jack-knife," and the other stopper is inserted in the opposite stopper hole
t of the other "jack-knife, so that a single announcer is in derivation circuit. In
order to put the announcer or relay in the circuit the connecting screws q, q', are
removed from the two plates, and a branch wire v, v, is connected to the insulated
plug of the inner plate. Fig. 11 shews to an enlarged scale several tablets of the
central station in order to show how the communications are established by the
connectors. As before stated, the subscribers are by preference connected in groups
of 25, and as far as possible those subscribers are grouped together that communicate
most often with each other. Assuming that there are two groups of 25 in each
tablet, and that there are 10 tablets of 50 subscribers, or 500 subscribers altogether,
at a central station, the electric connections of the connectors of the several tablets
would be as follows:-Those connectors bearing the same letters A, B, C, D, E, F, in
one and the same horizontal row are connected together; it is arranged that the
first row is to be devoted to the communications of the subscribers of the first
tablet with the others; that the second row corresponds with the second tablet,
and so on.
For instance, if the subscriber No. 15 of the first group of the first
tablet demands communication with No. 87 of the second group of the second
"

page_text: tablet, then the operator, having heard the call of No. 15, connects by the flexible
stopper couple the jack-knife 15 with a connector of the first row, say B. On the
other hand, after having called No. 87, he connects the jack-knife of the latter with
the connector B of the first row, taking care to put the stoppers in the jack-knives
in different holes, so that only one announcer shall be in circuit. Conversely if it
be a subscriber of the second tablet who desires communication, the stoppers are
put in the connectors of the second row. The lower rows of the connectors serve
for establishing communications, permanent or otherwise, from one station to
another.
Having thus described the nature of the said Invention, and in what manner
the same is to be performed as communicated to me by my foreign correspondents,
I claim,-
First. The herein described arrangement of the cables passing from the sub-
teranean conduit to the central station.
Second. The herein described arrangement and combination of the rosace with
one, two, three, four or more faces on which are established the connections
between the double wire of the cables and the double wires from the announcers
of the tablets.
Third. The herein described construction of double jack-knives.
Fourth. The herein described construction of double stopper for the flexible
coupling cable, operating in combination with the double jack-knife, as set forth.
Fifth. The herein described combination of the tablets with the connectors
serving to establish the communications from tablet to tablet.
Sixth. The combination of parts herein described constituting telephonic apparatus
for central stations.
In witness whereof, I, the said Charles Denton Abel, have hereunto set my
hand and seal, this Twenty-eighth day of February, in the year of our
Lord One thousand eight hundred and eighty-two.