IMPROVEMENTS IN TELEPHONIC AND TELEGRAPHIC APPARATUS
Year: 1885

page_text: I, JOHNSTON STEPHEN, of Ravelston Cottage, Blackhall, in the County of
Midlothian, North Britain, Journalist do hereby declare the nature of the said
invention for IMPROVEMENTS IN TELEPHONIC AND TELEGRAPHIC APPARATUS, to
be as follows:—
This Invention, which relates to Improvements in Telephonic and Telegraphic
apparatus, has for its object to provide a switch table which may either be operated
by an attendant at the central station or Exchange, or automatically by the
subscribers themselves.
In carrying out this Invention, at the central station there is provided a number
of bars which may be of Mahogany or of other insulating material. For each
subscriber to the Exchange there is provided a pair of bars which run, say from
West to East, one of such pair of bars being situated above the other but held
apart therefrom by distance pieces also of insulating material. Each subscriber has
also a similar pair of bars which run say from North to South situated preferably
below the herein first mentioned pair. All the subscribers being thus provided it
will be seen that in the aggregate there is formed a network of bars wherein each
West and East pair of bars will intersect at some portion of its length the lines of
all the north and south pairs of bars. In the manner hereinafter described the
West and East bars carry strips of electrical conductors which, together with the
discs hereinafter mentioned, forin a portion of the circuit which may be described
as the "calling" portion, and the north and south bars in like manner form part of
the circuit which may be described as the "called" portion.
At the points of intersection of these bars are holes, through which pass pins or
rods which may be wholly of insulating material. These pins or rods are provided
with discs or their equivalent of electrically conducting material, two of which
discs normally are in such position upon the metallic strips herein before described
that they close the earth connections of the "calling" and the "called" lines
respectively, but if one of the pins and with it the two discs be lifted up, such
connections with earth are broken. It will now be seen that the first step towards
switching together two subscribers to a telephone Exchange vizt that of breaking
the earth connections of both has been effected. Each of the west and East bars
carries metallic strips which together with metallic discs secured to the pins or
rods form part of a line which passes in this way along the West and East bar and
Price 81

page_text: The
through the metallic strips of the corresponding north and South bar which are
perforated to allow the pins or rods to pass through, to an insulator. The line
I called free circuit."
herein last described is referred to hereinafter as the "
West and East bars also carry metallic strips perforated to allow the pins or rods
to pass through, these strips end at their Eastmost extremities on insulators. On
the rise of one of the pins or rods, the Earth circuits of the "calling" and
"called" subscribers are broken as herein before described, one of the discs on the
said pin or rod will now make electrical contact with the metallic strip which
terminates on an insulator at its eastmost extremity. Another disc will make
electrical contact with the perforated metallic strip on the north and south bar.
The fifth disc or that which normally forms, with the conducting strips, the line
which ends on the southmost insulator by rising off these strips prevents the
possibility of circuit therethrough. The two discs which have now come up
against, and are in electrical connection, the one with the strip on the West and
East bar (vizt the calling line) and the other with the strip on the north and south
bar (vizt the called bar). These two discs are electrically connected together by a
wire or otherwise. It will now be seen that by this action of the pin or rod rising,
the earth connections of the "calling" and "called" subscribers are broken, and
electrical connection is made between a free branch from the line of the "calling"
subscriber and a free branch of the line of the "called" subscriber, thereby allowing
the two subscribers to communicate, while, by the rise of the fifth disc herein before
referred to, the possibility of another subscriber connecting his line with the line
of the "calling" subscriber, is prevented. To prevent the possibility of any other
person "calling" an already "called" subscriber, the pins or rods at their lower
extremities are provided with hooks or loops. Through the loops of those pins
forming North and South lines a cord or its equivalent is passed. Between each
of these loops the cord passes under a pulley or its equivalent, secured in any
convenient manner to any fixed part. This cord is secured at its two extremities
and it is of such a length that there is sufficient "slack" to admit of one pin or rod
only rising at one time. Each of the pins or rods herein before described is
provided at its upper extremity with a soft iron armature.-Over each of these
armatures there is situated an electro-magnet which is preferably constructed with
a single core having attached to its upper extremity a piece or band of soft iron
which is bent downwards along the side of the coil and again at right angles
At its last turn this band has a hole formed in it, through which the pole face of
the core is exposed, the surrounding portions of soft iron forming the opposing
pole face. The manner of directing the current of electricity from a local battery
through any one of the coils of these electro-magnets and the method of continuing
their magnetization is set forth in the Provisional Specification of the said
Johnston Stephen N° 13670 dated October 16th A.D. 1884.
The construction, connections and method of using the vibratile coils employed
in connection with the switch table is also set forth in the aforesaid Provisiona
Specification, and therefore need not here be further referred to.
If an annunciator be insertable in each subscriber's circuit and if the circui
from the local battery through any one of the electro-magnets be closeable by
press-button or its equivalent, it will be seen that the switchings may be effecte
by an attendant.

page_text: Improvements in Telephonic and Telegraphic Apparatus.
I JOHNSTON STEPHEN of Ravelston Cottage Blackhall in the County of Mid-
lothian North Britain Journalist 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 :-
This Invention which relates to improvements in Telephonic and Telegraphic
apparatus has for its object to provide a switch table which may either be
operated by an attendant at the central station or exchange or automatically
by the subscribers themselves.
I will explain my Invention with reference to the accompanying diagrams,
Figure 1 representing the arrangement of bars as hereinafter described in plan
Figure 2 representing the same in transverse section in connection with the other
devices used therewith and Figure 3 representing (drawn to a larger scale) the
details of two of the contact makers used in the system of bars constituting the
switch table one shewing the normal position and the other the position when two
subscribers are in communication.
At the central station there is provided a number of bars of insulating material
such as mahogany for example. For each subscriber to the Exchange there is
provided a pair of bars a b which run say from West to East, one of such pair of
bars being situated above the other but held apart therefrom by distance pieces c
also of insulating material. Each subscriber has also a similar pair of bars e f
which run say from North to South and situated preferably below the herein. first
mentioned pair a b. All the subscribers being similarly provided with bars it will
be seen that in the aggregate there is formed a network of bars wherein each West
and East pair of bars will intersect at some portion of its length the lines of all the
North and South pairs of bars. The West and East bars a b carry strips of
electrical conductors g. h. h² which together with the discs or contact makers
hereinafter mentioned form a portion of the circuit which may be described as the
"calling" portion and the North and South bars ef in like manner carry conduct-
ing strips e2f2 which form part of the circuit which may be described as the
"called portion."
The conducting strips of the bars of the calling portion are electrically connected
with those of the called portion as shewn in the diagram Figure 4 which indicates
six subscribers stations at 1. 2. 3. 4. 5 and 6 all running to one exchange and
connected to their respective bars of the calling portion and thence by the con-
ducting wires represented at a² respectively to the corresponding bars of the called
portion so that each subscriber's calling portion crosses the called portion of all the
other subscribers and may be connected to any one of them by electrical connections
effected at these points of intersection as by the raising of one of the pins j herein
after referred to.

page_text: This is effected by an arrangement which is shewn in Figure 2 and more clearly
in Figure 3.
At the points of intersection of the bars a band ef are holes i through which
pass pins or rods j which may be wholly of insulating material. These pins or
rods are provided with discs or their equivalent constituting contact makers of
electrically conducting material, two of which discs those marked klare normally
in such position upon the metallic strips g and f" that they close the earth connec
tions of the "calling" and the "called" lines respectively-If one of the pins and
with it the discs be lifted such connections with earth are broken which is the first
step towards switching together two subscribers to a telephonic or telegraphic
Exchange The strip h on the West and east bars is connected at one end with the
line wire and at its other extremity terminates on an insulator as at h³. The
metallic strips h² on the West and East bars are connected at one of their
extremities with the line wire and at their other ends with the strips e² of the
respective or corresponding north and south bars and thence lead to insulators e³
The strips h and e² terminating in insulators and e³ are each metallically
continuous or connected throughout the length of their bars and not interrupted
electrically at the places where the rods j pass as is the case with the other strips
unless they are bridged by the contact pieces or discs on the rods j. All the strips
and bars are of course perforated for the passage of the rods-On the rise of one of
the pins or rods j the earth circuits of the "calling" and "called "subscribers are
broken by the contact pieces and leaving the strips g and f² and a contact piece
or disc on the said pin or rod will now make electrical contact with the metallic
strip h and another contact maker or disc e* will make electrical contact with the
stripe on the north and South bar and thus put the two subscribers in communi-
cation The fifth disc or contact piece 5, which normally forms with the conducting
strips the line which ends on the Southmost insulators e", by rising off the strip h³
prevents the possibility of circuit there-through and consequently of interference
with two subscribers who are speaking by other subscribers-The two discs or
contact pieces and e* which have now come up against and are in electrical
connection with the strips h and e² respectively, as shewn in Figure 3 are
electrically connected together by a wire or otherwise-It will now be seen that
by this action of the pin or rod rising the earth connections of the "calling" and
called" subscribers are broken and electrical connection is made between a free
branch from the line of the "calling" subscriber and a free branch of the line of
the called subscriber thereby allowing the two subscribers to communicate while
by the rise of the fifth disc h³ the possibility of another subscriber connecting his
line with the line of the " calling" subscriber is prevented To prevent the
possibility of any other person "calling" an already "called" subscriber the pins
or rods of each series of the north and south bars at their lower extremities are
provided with hooks or loops as shewn in Figure 5 and through the loops
of those pins a cord or its equivalent is passed. Between each of these loops the
cord m passes under a pulley or its equivalent secured in any convenient manner
to any fixed part This cord is secured at its two extremities and it is of such a
length that there is sufficient "slack" to admit of one pin or rod only rising at one
time.
16
Figure 6 is a dragram intended to render clear the connections of each subscriber
and to illustrate the way in which he is connected with any one of the other sub-
scribers with whom he may desire to speak The line marked 1. 1 is one of those
through the West and East bars which I have designated the calling portion and the
line marked 2. 2. is one of those through the North and South bars which I have.
designated the called portion. g is the portion corresponding to that which passes
through the strip g to earth and, f2 is the portion which normally passes through
the strip to earth and the parts marked h² and e² are the portions which pass
through the strips marked h h and e²-It will now be understood that when any
one subscribers contact, making and breaking rod j is raised the lines to earth will

page_text: be broken as indicated at x and electric connection will be established between n
nd e as indicated at thus putting the two subscribers in communication with
ach other and the conductor at 2 will be broken as indicated at y to prevent
nterference with other subscribers.
The herein before described contacts may be operated by hand at the central
tation or they may by the following arrangement be operated by a subscriber from
his own particular station so that he can switch his line onto that of any one of
the other subscribers with whom he may desire to communicate; the said arrange-
ment is as follows.
Each of the pins or rods j is provided at its upper extremity with a soft iron
arinature . Over each of these armatures there is situated an electro-magnet n
which is preferably constructed with a single core having attached to its upper
extremity a piece or band of soft iron which is bent downwards along the side of
the coil and again at right angles. At its last turn this band has a hole formed in
it, through which the pole face of the core is exposed, the surrounding portions of
soft iron forming the opposing pole face. This is shewn at Figure 7. The manner
of directing the current of electricity from a local battery through any one of the
coils of these electro magnets and the method of containing their magnetization is
set forth in the Specification of my application for Letters Patent No 15,439 dated
November 24th A.D. 1884.
The construction, connections and method of using the vibratile coils employed
in connection with the switch table is also set forth in the aforesaid Specification.
I will describe the arrangements for the purpose which I have shewn in diagram in
Figure 2. p is a local battery the circuit of which is normally interrupted at q q and
normally closed at r. When contact is made at either of the contacts q the current
passes round the corresponding electro magnet n and it is energised and attracts
the armature j³ for raising the rod j for making and breaking the contacts on the
west and east and north and south bars as aforesaid. In order to keep the magnet
energised and thus maintain the rod in its elevated position whilst the subscribers
are speaking the armature on rising makes contact at s which causes a current to
pass from the battery by the wires & as will be well understood by referring to
Figure 2 The contacts at q are operated as desired by means of vibratile coils
indicated at t which are arranged to operate cither contact as required as described
in my aforesaid Specification. When the subscribers have finished their com-
munication the current is caused to actuate the vibratile coil at m to break contact
at and thus demagnetize that electro magnet n which held up the rod j through
which the contacts were made for the communication. It will be understood that
the vibratile coils are timed to operate independently so that the only desired
contact is made substantially as described in my aforesaid Specification. The blank
spaces at the crossings of the bars where no rod is situated it will be understood
is the place where the subscribers west and east bar crosses his north and south bar
and of course at these points no contacts are required to be made or broken.
If an annunciator be provided at the exchange (one in each subscribers circuit)
and if the circuit from the local battery through each of the electro magnets be
provided with a press button or its equivalent it will be seen that the switchings
may be effected by an attendant at the station instead of by the subscribers them-
selves from their stations. Or the rods j may be raised and lowered by the direct
action of the attendant at the central station.
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
First. The general arrangement of parts and circuits constituting the telephonic
or telegraphic exchange system substantially as hereinbefore described and explained
with reference to the accompanying Diagrams.

page_text: Second. The switching board or device consisting of the construction of crossed
bars and contact strips or pieces and contact making and breaking devices capable
of making and breaking at all the required places at once to insolate any two
subscribers and put them in communication with each other substantially as hercin-
before described and illustrated by the accompanying diagrams whether the said
switching board or device be operated electrically by the subscribers from their
stations or by the attendant at the exchange station.