IMPROVEMENTS IN APPARATUS EMPLOYED IN CONNECTION WITH TELEPHONES FOR THE PURPOSE OF NOTIFYING AND OF FACILITATING AND OBTAINING INTERCHANGEABLE COMMUNICATION BETWEEN TELEPHONIC CIRCUITS
Year: 1879

page_text: LETTERS PATENT to Arnold White, of Queen Victoria Street, in the City of
London, for the Invention of "IMPROVEMENTS IN APPARATUS EMPLOYED IN
CONNECTION WITH TELEPHONES FOR THE PURPOSE OF NOTIFYING AND OF
FACILITATING AND OBTAINING INTERCHANGEABLE COMMUNICATION BETWEEN
TELEPHONIC CIRCUITS." A communication from Thomas Alva Edison, of
Menlo Park, in the State of New Jersey, in the United States of America.
PROVISIONAL SPECIFICATION left by the said Arnold White at the Office
of the Commissioners of Patents on the 20th September 1879.
ARNOLD WHITE, of Queen Victoria Street, in the City of London. "IMPROVE-
MENTS IN APPARATUS EMPLOYED IN CONNECTION WITH TELEPHONES FOR THE
PURPOSE OF NOTIFYING AND OF FACILITATING AND OBTAINING INTERCHANGEABLE
COMMUNICATION BETWEEN TELEPHONIC CIRCUITS." A communication from Thomas
Alva Edison, of Menlo Park, in the State of New Jersey, in the United States of
America..
This Invention relates to improvements in the methods by which two separate
electric circuits may be quickly united to form one, and as quickly divided so as to
again constitute two distinct circuits. And further, in improvements in electrical
annunciators whereby notice is conveyed to an attendant at a central station or
other distant point that his attention is required. And further, in the combination
of an electrical circuit connecting board and an electrical annunciator for the
especial purposes and uses of telephonic exchanges and other stations.
By means of this Invention the following advantages are obtained :-
1st. Condensation of a large number of wires in a small space, thus offering
extraordinary facilities for rapid cross connections.
2nd. Economical construction.
3rd. Enabling one attendant to attend to a larger number of wires than by the
methods heretofore in use.
4th. The method whereby the number or name of the station requiring attention
is exposed to the attendant as well also as the superior simplicity and effectiveness

page_text: .
In carrying out this Invention the apparatus is constructed and arranged in the
following manner :-
A series of two or more electro magnets are affixed to a parallel bar supported
within a frame; there may be one or more rows of these magnets one above the
other, or otherwise arranged. Attached to a cast metal frame which supports each
electro magnet is an angle piece, which serves the double purpose of providing a
means for securing the whole to the face of the parallel bar and of projecting a
fixture, to which is attached the device for disclosing a number, name, or other sign
indicative of the particular magnet in action. This device consists of a small metal
shutter, hinged at the bottom, so that when in an upright position it conceals the
sign character, but when released and permitted to fall it uncovers it. The sign
may be either upon the reverse face of the drop itself or upon the face of a stationary
support immediately behind it when it is in an upright position. The drop is held
in an upright position by means of a niche or other device affixed to or upon the
end of an extension of the armature of the electro-magnet, and upon the drop the
extension is pivotted near its junction with the armature in such a manner that
when the armature is depressed by the attraction of the magnet the extended arm
is raised and the drop is released from the niche and allowed to fall. In order to
reduce the friction between the arm and the drop to a minimum the drop is brought
as near as possible to an upright position without reaching a dead centre, from
which it could not move by its own gravitation.
The circuit connecting board is supported within the same frame as the electro-
magnets and immediately underneath them, and consists of a series of metal upright
and horizontal bars so arranged that the upright bars lie across the face of the
horizontal bars without being in contact. This is effected by setting them into
grooves cut in the face of a wooden or other nonconducting frame, which grooves
are deeper for the horizontal than for the upright bars.
In order that the surfaces of both may present one common plane the horizontal
bars are cast with projecting lugs of a height equal to the thickness of the upright
bars, and of a thickness a trifle less than the space between the upright bars. In
this manner two series of bars, one upright and one horizontal, are laid across each
other and made to present one common plane without being in actual contact.
Holes are then drilled (for the insertion of a metal pin) at every point of crossing
of the two series of bars, the object being by the insertion of the pin at will to
obtain metallic connection between any two uprights.
The function of the horizontal bars is simply to intersect or join together by the
aid of the pin any two of the uprights.
It is apparent that this relative position may be changed and the uprights made
to serve as the connection for any two horizontals.
The electrical operation of this telephone combination of annunciator and inter-
connecting bars will appear from the following description of the arrangement of
the circuit :-
The conducting wire conveying the electro currents from the distant station is
brought to a small screw cup attached to the top of the frame, and passes from
thence by means of fine insulated wires directly to one end of the electro magnet of
the annunciator, and from the other end to the top of an upright bar, and traversing
this intersects one of the horizontal bars by means of the metal pin, this particular
horizontal bar being connected by wire with the earth; thus the circuit is com-
plete from the line to the earth through the annunciator magnet and upright bar,
each electro magnet and upright bar serving for a separate line.
If now it is desired to join electrically any two telephone lines it is only necessary
to remove the pins of each from the point of junction with the earth connected hori-
zontal bar, and insert them at the point of junction of their respective uprights and
a free horizontal.
}
It will be seen that the two lines which are thus made one electric circuit
continue to pass thro' their respective annunciators, and it is only necessary for
either distant station to transmit an electric pulsation from their signal batteries or

page_text: machines to operate the annunciators, and thus signify that they have finished and
wish their wires separated from each other and reconnected with the earth bar, the
annunciator drops previously thrown down by the original signals having been
meanwhile restored to their upright position by the attendant. The circuits may
be made in many ways through the electro magnets and bars, but the one herein-
before described is found to be convenient in practice.
It is of course apparent that when A wishes to be put in communication with B
he has but to signal to the attendant, who connecting his telephone in circuit
inquires his wishes. Upon receiving the response he immediately connects A and B,
as before described; A then calls B direct, B responding affects the annunciators
as well.
The cessation of all movement in the armatures of the electro magnets is the
signal to the attendant that A and B are now talking. He then restores the drops
to position and awaits their simultaneous dropping as his signal to separate
them.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Arnold White in the Great Seal Patent Office on the 19th March
1880.
ARNOLD WHITE, of Queen Victoria Street, in the City of London. " IMPROVE-
MENTS IN APPARATUS EMPLOYED IN CONNECTION WITH TELEPHONES FOR THE
PURPOSE OF NOTIFYING AND OF FACILITATING AND OBTAINING INTERCHANGEABLE
COMMUNICATION BETWEEN TELEPHONIC CIRCUITS." A communication from abroad
by Thomas Alva Edison, of Menlo Park, in the State of New Jersey, in the United
States of America.
The said Invention relates to improvements in the methods by which two separate
electric circuits may be quickly united to form one, and as quickly divided so as to
again constitute two distinct circuits. And further, to improvements in electric
annunciators, whereby notice is conveyed to an attendant at a central station or
other distant point that his attention is required. And further, in the combination
of an electric circuit connecting board, and an electric annunciator for the especial
purposes and uses of telephonic exchanges and other stations.
:-
By means of the said Invention the following advantages are obtained :-
First. Condensation of a large number of wires in a small space, thus offering
extraordinary facilities for rapid cross connections.
Second. Economical construction,
Third. Enabling one attendant to attend to a larger number of wires than by the
methods heretofore in use.
Fourth. The method whereby the number or name of the station requiring
attention is exposed to the attendant, as well also as the superior simplicity and
effectiveness of the apparatus.
In carrying out the said Invention the apparatus is constructed and arranged in
the following manner, reference being made to the Sheet of Drawings hereunto
annexed, in which Figure 1 represents a front elevation of the apparatus, and
Figure 2 is a transverse vertical section of the same.
To a bar A supported within a frame B is affixed a series of two or more electro
magnets C, by means of cast metal frames D and screws.
There may be one or more rows of these magnets one above the other, or otherwise
arranged. The Drawing represents two rows of electro magnets C, carried respectively
by two bars A, A, arranged one above the other, each row containing 12 electro
magnets. The metal frames D which support the electro magnets form angle pieces
which serve the double purpose of providing a means for securing the electro
magnets to the face of the bars A, and of carrying a device for disclosing a number,
name, or other sign indicative of the particular magnet in action.
This device consists of a small metal drop or shutter a hinged at the bottom b, so
that when in an upright position it conceals the sign or character, but when
released and permitted to fall it uncovers it. The sign may be either upon the
reverse face of the drop itself or (as is assumed in the example illustrated) upon the
face of a stationary support c immediately behind the drop a, or when it is in an
upright position. The drop is held in an upright position by means of a niche or
other device affixed to or upon the end of an extension d of the armature e of the
electro magnet, and upon the drop the extension d is pivotted at f, near its juncture
with the armature e in such a manner that when the armature is depressed by the
attraction of the magnet, the extended arm d is raised, and the drop is released
from the niche and allowed to fall. In order to reduce the friction between the
arm d and the drop to a minimum, the drop is brought as near as possible to an
upright position without reaching a dead centre, from which it could not move by
its own gravitation.

page_text: In the Drawing, Figure 1, the drops of the eighth and seventeenth electro
magnets are represented as down, exposing the numbers 8 and 17 respectively,
the other drops being represented in their raised position, concealing their respective
numbers.
The apparatus hereinbefore described constitutes an electric annunciator, which
may be used for conveying notice to an attendant at a central station or other
distant part that his attention is required.
The circuit connecting board which forms another part of the said Invention is
supported within the same frame as the electro magnets, and immediately under-
neath them. It consists of a series of metal upright bars E, and of metal horizontal
bars F so arranged that the upright bars lie accross the face of the horizontal bars
without being in contact with them; this is effected by settling the horizontal bars
upon the face of a wooden or other non-conducting frame G, and supporting the
upright bars upon intervening bars H of wood or other nonconducting material
made of a suitable height.
In order that the surfaces of both the upright bars E and the horizontal bars F
may present one common plane, the upright bars are let into recesses in the
horizontal bars slightly exceeding in width the width of the upright bars. In this
manner two series of bars, one upright, and one horizontal, are laid accross each other
and made to present one common plane without being in actual contact. Holes g
are then drilled (for the insertion of a metal pin I) at every point of crossing of the
two series of bars, the object being by the insertion of the pin at will to obtain
metallic connection between any two uprights. The function of the horizontal
bars is simply to intersect or join together by the aid of the pin any two of the
uprights. It is apparent however that the converse of this arrangement may be
adopted, that is to say, that the uprights may be made to serve as the connection
for any two horizontals.
The electrical operation of this telephonic combination of annunciator and
inter connecting bars or electric circuit connecting board will appear from the
following description of the arrangement of the circuits :-
Let it be assumed that the lowest horizontal bar of the series is connected with
earth by means of a wire h, and that the pins I are inserted in the holes in this bar
(some of the pins are however represented as removed in the Drawing). Taking
the first upright bar as an example of the operation of the whole, the conducting
wire conveying the electric currents from the distant station is brought to a small
binding screw k attached to the top of the frame, and passes thence by means of
fine insulated wire / directly to one end of the electro magnet of the annunciator,
and from the other end (by a connection with a binding screw m) to the top of the
upright bar, and traversing this intersects the lowest horizontal bar by means of
the metal pin, this particular horizontal bar being connected by wire with the earth,
as before mentioned. The circuit is thus complete from the line to the earth through
the annunicator magnet and upright bar. A similar arrangement is adopted in the
case of all the electro magnets and upright bars, each electro magnet and upright
bar serving for a separate line. One of the horizontal bars (videlicet, the seventh in the
example assumed) is connected by a wire n with a telephone K, in proximity to
the apparatus in order that the attendant at the central station may be able to
communicate with any one of the twenty four telephonic lines connected with the
apparatus. If now it is desired to join electrically any two telephonic lines, it is
only necessary to remove the pins of each from the points of junction with the earth-
connected horizontal bar (the lowest bar in the example assumed), and insert them
at the point of junction of their respective upright bars, and a free horizontal bar
and the two lines are thus made one electric circuit whilst continuing to pass
through their respective annunciators.
In order that the mode of using this combined electric annunciator and electric
circuit connecting board for the purpose of telephonic exchanges and other central
stations may be fully understood, let it be assumed that at a distant station, say,
for example, one connected with No. 8 electric magnet wishes to communicate with

page_text: B at another distant station, say, for example, one connected with No. 17 electro
magnet,
A first signals to the attendant at the central station or exchange by sending an
electric pulsation from its signal battery or machine to operate the annunciator,
and the drop of No. 8 magnet falls displaying the figure 8, as shewn in the Drawing,
Figure 1. The attendant then removes one of the pins from the lowest horizontal
bar, and places it in the hole at the point of intersection of No. 7 horizontal bar
with No. 8 upright bar, whereby No. 8 line is placed in circuit with the telephone
at the exchange. The attendant next enquires of A his wishes, and receiving a
response that he wishes to be connected with No. 17 line, the attendant places
the pin corresponding to No. 8 in the hole at the point of intersection of No. 8
upright bar with one of the free horizontal bars, (the second in the example
assumed) and places the pin corresponding to No. 17 in the hole at the point of
inter section of No. 17 upright bar with the same horizontal bar. Lines Nos. 8 and
17 are then in circuit, and A calls B direct, B responding affects the annunciator,
and the drop of No. 17 falls. The apparatus is then in the condition indicated in
the Drawing. The cessation of all movement in the armatures of the electro
magnets is the signal to the attendant that A and B are now talking, he then
restores the drops to their normal position and awaits their simultaneous dropping
as his signal to separate the two lines by restoring the two pins to their respective
places on the lowest horizontal bar.
It will be understood that if required any other or all of the lines may be
similarly connected in pairs at the same time.
When a greater number of lines than that provided for in the example of apparatus
illustrated is required to be connected with the exchange, an additional set of electro
magnets may be provided at the side of those shewn, and the upright bars E may
be extended downwards, as represented at E', and an additional set of horizontal
bars be provided below the others, as indicated at F', in Figure 1.
Having now described and particularly ascertained the nature of the said
Invention, and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion that what I consider to be novel and original
and therefore claim as the Invention secured to me by the hereinbefore in part
recited Letters Patent is,-.
First. The general construction and arrangement of electric circuit connecting
board, whereby any two separate electric circuits may be quickly united to form
one, and as quickly divided so as to again constitute two distinct circuits, substan-
tially as herein before described.
Secondly. The general construction and arrangement of electric annunciator,
substantially as and for the purpose hereinbefore described.
Thirdly. The combination of an electric circuit connecting board, and an electric
annunciator, both constructed and arranged substantially in the manner and for the
purpose hereinbefore described.
In witness whereof, I, the said Arnold White, have to this my Specification
set my hand and seal, this Eleventh day of March, One thousand eight
hundred and eighty
ARNOLD WIHTE. (L.S.)