IMPROVEMENTS IN ELECTRICAL APPARATUS CHIEFLY DESIGNED FOR TELE- GRAPHIC AND TELEPHONIC PURPOSES
Year: 1881

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for an Invention of
"IMPROVEMENTS IN ELECTRICAL APPARATUS CHIEFLY DESIGNED FOR TELE-
GRAPHIC AND TELEPHONIC PURPOSES." A communication from abroad by
Charles Williams, junior, and Frank Ward Harrington, both of Somerville,
and Thomas Whittemore Lane, of Boston, all of Massachusetts, United States
of America.
PROVISIONAL SPECIFICATION left by the said William Robert Lake at
the Office of the Commissioners of Patents on the 15th August 1881.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN ELECTRICAL APPARATUS
CHIEFLY DESIGNED FOR TELEGRAPHIC AND TELEPHONIC PURPOSES." [A com-
munication from abroad by Charles Williams, junior, and Frank Ward Harrington,
both of Somerville, and Thomas Whittemore Lane, of Boston, all in Massachusetts,
United States of America.]
This Invention relates to improvements in electrical apparatus chiefly designed
for telegraphic and telephonic purposes, and comprises various novel features
hereinafter described.
The first part of my said Invention has special reference to magneto generators,
and has for its object to automatically put the generator into and out of a circuit
when required to send a magneto current over the line for signalling or other
purposes. In the generators heretofore used for such purposes it has been
customary to momentarily or continuously put the generator into and out of tho
circuit by pressing and releasing a push knob, the current passing into the line
while the said knob was depressed, and the armature revolved between the poles
of the magnet.
According to my Invention I provide means for putting the generator in circuit
by the same operation which causes the armature to rotate, thus automatically
631....מ,

page_text: performing what has heretofore been effected by a separate operation, and causing
the generator to be automatically cut out of the circuit when the armature ceases
to rotate.
I provide a base of suitable material, upon which is fixed a magneto generator
of any desired form, for instance, one of the ordinary "Siemens" armature type.
The armature is secured and rotated between the poles of magnets; a shaft carries
the armature, one end of which has bearing against it a spring, which is rigidly
fastened to a foot, the other end of the shaft having fixed upon it a pinion, which
meshes with a gear wheel, whose shaft is suitably secured in bearings. The outer
end of the latter shaft is turned down. A sleeve is arranged to slide upon the
outer end of this shaft, having at one end a crank handle, and an enlarged chamber
at the opposite end, within which is located a spiral spring. This spring is secured
at each end, one end in the enlarged portion of the shaft, the other in the sleeve.
There is a disc which forms a part of the sleeve, upon the side of which (when it is
in its normal condition) a spring bears. A cam slot is cut through the sleeve, and
a screw is driven firmly into the shaft, its head projecting above the surface of the
shaft to form a guide for the cam-groove; screw posts are provided, to which the
line wires are secured. There is a metallic connection between two feet, and one
between one of the feet and one of the posts, and one between the other binding
post and the armature. In the normal condition of the generator the circuit passes
through such parts of the apparatus as to avoid the resistance occasioned by the
armature coil, and passes through the generator with little or no resistance.
When it is desired to use the generator to transmit the current to the line, the
operator turns the crank, which resists rotation. By the inertia of the parts of
the machine and by the action of the spring in the chamber (which forces an
abutment of the cam slot against the screw) I arrange the parts however so that
the resistance of the spring is less than the inertia and friction of the machine, so
that by pressing the crank handle around, the spring yields, and the sleeve rotates
upon the shaft until the abutment of the cam-slot strikes the opposite side of the
screw head, when by continued pressure the gear wheel is caused to turn and
rotate the armature. As the sleeve rotates upon the shaft, the cam slot, by its
inclined sides pressing upon the screw-head, causes said sleeve to rotate spirally
and to move around and along the shaft inwardly, and cause the disc to move
away from the spring, and thus break the contact between the two parts, and as
long as the pressure is exerted upon the crank handle the separation continues:
By this separation of the disc from the spring the circuit normally existing (as
previously. described) is broken, and the generator put in a position to send
magneto currents into the line. It will be readily seen that the generator is
automatically cut into and out of the line circuit by the separation of the spring
and disc, and that currents of any duration can be passed to the line, and that
upon releasing the crank it is forced back to its normal position.
According to a modification the sleeve spring is arranged on the opposite side of
the disc, and the chamber-spring is adapted to press the disc toward the sleeve
spring. The end of the gear-wheel-shaft is provided with a bevelled face, and a
projection at the outer portion of said face. The sleeve is provided with a pin,
which is pressed by the force of the chamber-spring against the face. When the
sleeve is rotated the face acting on the pin causes the sleeve to move outwardly
on the shaft, thereby separating the disc from the spring until the pin strikes the
projection, which arrests the outward movement of the sleeve and causes the sleeve
to rotate the shaft.
My Invention further relates to that class of telephone switch boards in which
the line circuit strips are provided with springs adapted to bear with a yielding
pressure against plugs inserted through perforations in the insulated connecting
strips, which cross the board at right angles with the line circuit strips. Heretofore
in this class of switch boards the springs of the line circuit strips have been so
arranged that each plug receives the pressure of but one spring directed against one
side of the plug. This part of my Invention has for its object to so arrange said

page_text: springs that each plug shall receive the pressure of two springs bearing on opposite
sides, so that a more reliable and positive contact will be maintained, and one less
liable to be accidentally broken than in switch boards heretofore used.
To this end I provide the following arrangement, which I will now proceed to
describe:-I provide a switch-board having on its front side parallel connecting
strips, and on its opposite side line circuit strips arranged substantially at right
angles with the first named strips; perforations are made in the first named strips,
extending also through the board, and adapted to receive movable plugs; contact
springs are attached to the back of the switch board arranged in pairs, and con-
nected with the second line circuit strips, the springs of each pair being connected
with the same line-circuit strip. The springs of each pair are arranged to normally
bear against each other at their outer ends, and to coincide with the said per-
forations, so that a plug inserted in either of the perforations will also be inserted
between the springs of one of the pairs, and displace said springs in opposite
directions. The springs will therefore press against opposite sides of the plug, and
each will neutralize the tendency of the other to push the plug toward one side.
It will be observed that the springs thus arranged ensure an effectual connection
between the line circuit and the connecting strip through the medium of the plugs,
the latter being so supported by the springs that they cannot readily be displaced.
In case either spring of a pair becomes broken, the other spring being connected to
the same line circuit strip maintains the desired connection.
I prefer to connect each spring with the adjacent spring of the next pair by
forming the two springs from a single piece of metal, so that all the springs of each
line-circuit-strip will be connected independently of the line circuit strip. The
line circuit strips are normally connected to a ground strip as usual, and the
operation of connecting any two of the line circuits is performed in the usual
manner.
I also provide electrical switch-boards for use in telephone central offices and
exchanges in which there are improved means for enabling the operator at the
central office to place his listening telephone into and out of the circuit formed by
the line wires of two subscribers connected together by means of said switch
board.
In the ordinary method of ascertaining whether connected parties have ceased
conversation, the telephone is connected into the line by one of the telephone cord
wires, the other wire being grounded. In such a method the wire to line is so
connected usually by plugs, and spring-jacks, and other devices that the jars and
friction of the parts while being adjusted cause unpleasant sounds to be conveyed
over the line wire to the ears of the parties conversing, and consequent annoyance.
Another disturbance is occasioned by the grounded wire of the telephone causing
more or less leakage of the electrical current to the ground, and thereby diminishing
the volume of sound transmitted to the listening parties, oftentimes rendering it
impossible to transmit speech.
By means of this Invention the said objections are eliminated, and the telephone
is put noiselessly into circuit, and the transmitted current is caused to pass through
the telephone without losing its strength by leakage, or from any other cause.
In carrying this part of my Invention into practice I provide a board or backing
of suitable insulating material, arranged upon the front of which are the usual
horizontal insulating metallic connecting strips adapted to be connected by means
of plugs or other suitable devices with the line circuit strips, which cross the board
at right angles to the other strips, and are in this instance arranged on the opposite
side of the board from the last named strips.
The line-circuit-strips, the connecting strips, and the devices for connecting them
may be of any suitable construction as far as relates to their joint operation. The
line circuit strips may be composed of springs arranged in pairs attached at their
bases to the board, and pressed together normally at their outer ends, and continuous
metal strips extend along the bases of the springs, the connecting strips being
provided with holes coinciding with the meeting faces of the springs, and receiving

page_text: plugs adapted to be inserted between the springs of each pair to connect the line-
circuit-strips with the connecting strips.
I make each line circuit strip capable of separation into two distinct parts at a
given point, and this is preferably accomplished by means of two springs in each
strip, said springs forming a part of the strip, and being attached to the board
and normally pressed together at their outer ends, like the line-circuit springs,
but unlike the last named springs they are entirely disconnected or insulated from
each other at their bases, so that when separated and insulated at their outer ends
they convert the strip to which they belong into two distinct parts having no
electrical connection.
The listening telephone is included in a listening circuit composed of
wires or cords, and means whereby one of said wires may be connected to one
of the parts of the line circuit strips (when the same is broken), and the
other part, thereby looping in the listening telephone and causing the entire
current to pass around through the listening circuit in passing through the line
circuit strip with which said circuit is connected. The means for connecting the
said wires respectively with the parts of the line circuits are preferably composed
of springs arranged between the separating springs, and normally separated from
the latter and from each other at their outer ends, so that when forced outwardly
a connecting and a separating spring will make contact with two other springs of
the same kind, some of the connecting springs being connected with each other and
with one of the connecting wires by a strip or wire and other connecting springs
with each other, and with the other connecting wire by a strip or wire through
suitable binding posts. The connecting and separating springs are arranged
opposite to a listening or central office telephone strip on the front of the switch
board, which strip is parallel with the connecting strips, and has holes coinciding
with the spaces between the connecting springs, so that a plug of insulating
material inserted in one of said holes will first press the-said springs outwardly
against the separating springs; and, secondly, separate the latter springs. The
line circuit strips pertaining to the separated springs are thus broken or separated
into two parts, neither having an electrical connection with the other, excepting
through the listening circuit through which the entire current passes from one part
of the line circuit strip to the other.
In a modification in the plug the same is composed of a body of insulating
material and plates secured to opposite sides. The connecting springs do not in
this instance touch the separating springs, the latter being separated by the plug
itself. The connecting springs are separated first, and then the separating springs
by the plug.
Another modification is employed, in which one terminal of each line circuit
strip at its separable point is composed of a fixed contact point and a spring, and
the other terminal is composed of a spring normally in contact with the point, and
insulated from the first spring by an insulating disc; a metallic strip extends
across the board parallel with the listening strip, and forming a back contact for
the first spring. In this modification the operator's telephone is connected with the
listening strip and with the metallic strip. A metallic plug is employed, and when
it is pressed into one of the holes of the listening strip it makes contact with one
spring, separates the latter from the point, thus breaking the line circuit strip, and
presses the other spring against the strip, thus looping-in the operator's telephone,
so that the circuit will be through the one spring, the metallic strip telephone and
metallic plug to the other spring. When the plug is withdrawn the last named
spring returns to the point, and the other spring separates from the strip, so that
the circuit passes directly through the line-circuit. It will be readily seen that the
act of pulling out a plug puts the telephone out of circuit in a manner as free from
disturbance and annoyance to the circuit as when the plug was introduced.

page_text: the said William Robert Lake in the Great Seal Patent Office on the
15th February 1882.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN ELECTRICAL APPARATUS
CHIEFLY DESIGNED FOR TELEGRAPHIC AND TELEPHONIC PURPOSES." A com-
munication from abroad by Charles Williams, junior, and Frank Ward Harrington,
both of Somerville, and Thomas Whittemore Lane, of Boston, all in Massachusetts,
United States of America.
This Invention relates to improvements in electrical apparatus chiefly designed
for telegraphic and telephonic purposes, and comprises various novel features
hereinafter described.
The first part of my said Invention has special reference to magneto-generators,
and has for its object to automatically put the generator into and out of a circuit
when required to send a magneto current over the line for signalling or other
purposes. In the generators heretofore used for such purposes it has been
customary to momentarily or continuously put the generator into and out of the
circuit by pressing and releasing a push knob, the current passing into the line
while said knob is depressed and the armature revolved between the poles of the
magnet.
According to my Invention I provide means for putting the generator in
circuit by the same operation that causes the armature to rotate, thus automatically
performing what has heretofore been effected by a separate operation and causing
the generator to be automatically cut out of the circuit when the armature ceases
to rotate.
In the accompanying Drawing,
Figure 1 represents a top view of a magneto-generator made in accordance with
my Invention.
Figure 2 represents a side view of the same.
Figure 3 represents a section on line 2, 2, of Figure 2.
The remaining Figures will be described hereinafter.
Upon a base A of suitable material is fixed a magneto generator of any desired
form, for instance, one of the ordinary "Siemens' armature type; A¹, A³, A³, are
magnets between whose poles the armature B is secured and rotated; C is the shaft
carrying the armature, one end of which shaft has bearing against it the spring D.
which is rigidly fastened to the foot D¹, the other end of the shaft C having fixed
upon it the pinion E, which gears with the toothed wheel F, whose shaft F¹ is
suitably secured in bearings. The outer end of the shaft F" is turned down, as
shown in Figure 3. G is a sleeve arranged to slide upon the outer end of the
shaft F. This sleeve has at one end the crank-handle H, and at its inner end an
enlarged chamber G', within which is located the spiral spring G³. This spring is
secured at its ends, as indicated in Figure 3, that is to say, one end is fixed to the
enlarged portion of the shaft F1 at F, and the other end to the, sleeve G at G³.
I is a disc forming a part of the sleeve, upon the side of which disc (when it is in
its normal position) the spring J bears; K is a cam-slot cut through the sleeve G,
as shewn; K¹ is a screw driven firmly into the shaft F1 its head projecting above the
surface of the shaft to form a guide for the cam-groove; L, L, are screw-posts, to
which the line-wires L' and 13 are secured; M is a metallic connection between the
foot J and the foot D¹; M³, between the foot D¹ and the binding post L; and M²
between the binding post L¹ and the armature B. In the normal condition of the
generator the circuit is as follows:-A magnetic current over line L³ passes through M
through the metallic surfaces of the generator, and by means of disc I, spring J,
foot J¹, wire M, foot D¹, wire M', to line wire L³, thus avoiding the great resistance

page_text: "
occasioned by the armature coil and passing through the generator with little or no
resistance.
When it is desired to use the generator to transmit a current to the line the
operator turns the crank H, which resists rotation by the inertia of the parts of the
machine, and by the action of the spring G³ in the chamber G1 (which forces the
abutment K² of the cam slot K against the screw head K¹). I arrange the parts,
however, in such a manner that the resistance of the spring is less than the inertia
and friction of the machine, so that by pressing the crank handle around, the spring
yields and the sleeve G rotates upon the shaft F¹ until the abutment K³ of
the cam-slot strikes the opposite side of the screw head K', when by continued
pressure the gear-wheel F is caused to turn and rotate the armature B.
As the sleeve G rotates upon the shaft F¹ the cam-slot by its inclined sides
pressing upon the screw-head K' causes the said sleeve to rotate spirally and to
move around and along the shaft F¹ inwardly and cause the disc I to move away
from the spring J (as shown in dotted lines in Figure 1), and thus break the
contact between the two parts, and as long as the pressure is exerted upon the
crank-handle the separation continues.
By this separation of the disc from the spring J the circuit normally existing (as
previously described) is broken and the generator put in a position to send
magneto currents into the line; as the line L³ makes a circuit from binding post L¹
by wire M² (which is in metallic contact with one end of the armature B, the said
armature being connected at its opposite end by spring D) by foot D¹, and wire M¹
through line L³ over which a magneto current passes when the generator is in
motion, it will be readily seen that the generator is automatically put into the
line-circuit by the separation of the spring J and disc I, that currents of any
duration can be passed to the line, and that upon releasing the crank it is forced
back to its normal position, that is to say, the abutment K³ of the cam-groove
against the screw K₁, thus bringing the disc I into contact with the spring J and
cutting the generator out of the circuit.
According to a modification the sleeve-spring is arranged on the opposite side of
the disc, and the chamber-spring is adapted to press the disc toward the sleeve-
spring. The end of the gear wheel shaft is provided with a bevelled face and a
projection at the outer portion of said face. The sleeve is provided with a pin
which is pressed by the force of the chamber-spring against the face.
When the
sleeve is rotated the face acting on the pin causes the sleeve to move outwardly on
the shaft, thereby separating the disc from the spring until the pin strikes the
projection, which arrests the outward movement of the sleeve and causes the
sleeve to rotate the shaft.
My Invention further relates to that class of telephonic switch-boards, in which
the line-circuit-strips are provided with springs adapted to bear with a yielding
pressure against plugs inserted through perforations in the insulated connecting-
strips which cross the board at right angles with the line circuit strips. Hereto-
fore in this class of switch boards the springs of the line-circuit-strips have been so
arranged that each plug receives the pressure of but one spring directed against
one side of the plug. This part of my Invention has for its object to so arrange
the said springs that each plug shall receive the pressure of two springs bearing on
opposite sides, so that a more reliable and positive contact will be maintained, and
.one less liable to be accidentally broken than in switch boards heretofore used.
This part of my Invention is represented in Figures 4 and 5 of the accompanying
Drawing.
•
Figure 4 represents a rear view of a portion of a switch-board embodying this
part of my Invention.
Figure 5 represents a section on line x, x, Figure 4.
a is a switch-board having on its front side the parallel connecting-strips b, b,
and on its opposite side the line circuit strips c, c, arranged substantially at right
angles with the strips b, b; d, d, are perforations in the connecting strips b, b,
extending also through the board and adapted to receive movable plugs e. Contact-

page_text: springs ff, are attached to the back of the switch board a, arranged in pairs and
connected with the line-circuit-strips c, as shown, the springs of each pair being
connected with the same line-circuit-strip. The springs of each pair are arranged
to normally bear against each other at their outer ends and to coincide with the
perforations d, so that a plug e inserted in either of the perforations will also be
inserted between the springs of one of the pairs and displace the said springs in
⚫opposite directions. The springs will therefore press against opposite sides of the
plug, and each will neutralize the tendency of the other to push the plug toward
one side. It will be observed that the springs thus arranged ensure an effectual
connection between the line-circuit and the connecting-strip through the medium
of the plugs, the latter being so supported by the springs that they cannot readily
be displaced.
In case either spring of a pair becomes broken, the other spring being connected
to the same line-circuit-strip maintains the desired connection.
I prefer to connect each spring with the adjacent spring of the next pair either
by forming the two springs from a single piece of metal, as shewn, or otherwise, so
that all the springs of each line-circuit-strip will be connected independently of the
line-circuit-strip. The line-circuit-strips are normally connected to a ground strip
as usual, and the operation of connecting any two of the line-circuits is performed
in the usual manner.
I also provide electrical switch-boards for use in telephone central offices and
exchanges with improved means for enabling the operator at the central office to
place his listening telephone into and out of the circuit formed by the line-wires of
two subscribers connected together by means of one of the said switch-boards.
In the ordinary method of ascertaining whether connected parties have ceased
conversation, the telephone is connected into the line by one of the telephone cord
wires, the other wire being grounded. In such a method the wire to line is usually
so connected by plugs and spring-jacks and other devices, that the jars and friction
of the parts while being adjusted cause unpleasant sounds to be conveyed over the
line wire to the ears of the parties conversing, and consequent annoyance. Another
disturbance is occasioned by the grounded wire of the telephone causing more or
less leakage of the electrical current to ground, and thereby diminishing the
volume of sound transmitted to the listening parties, oftentimes rendering it
impossible to transmit speech.
By means of this part of my Invention the said objections are eliminated, the
telephone is put noiselessly into circuit, and the transmitted current is caused to
pass through the telephone without losing its strength by leakage or from any
other cause.
•
This part of my Invention is represented in Figures 6 to 11 in the accompanying
Drawings.
Figure 6 represents a portion of a switch-board embodying this part of my
Invention.
Figure 7 represents a section on the line y, y, Figure 6.
Figure 8 represents an end view, showing the plug introduced and the telephone
in circuit.
Figures 9, 10, and 11 represent modifications.
N is a board or backing of suitable insulating material, arranged upon the front
of which are the usual horizontal insulated metallic connecting-strips g adapted to
be connected by means of plugs or other suitable devices with the line-circuit-
strips h which cross the board at right angles to the strips g, and are in this
instance arranged on the opposite side of the board from the last named strips.
The line-circuit-strips, the connecting-strips, and the devices for connecting
them, may be of any suitable construction as far as relates to their joint operation.
In this case the line-circuit-strips are shewn as composed of springs k, k, arranged
in pairs attached at their bases to the board, and pressed together normally at their
outer ends, and continuous metal strips h extending along the bases of the springs,
the connecting-strips being provided with holes coinciding with the meeting faces

page_text: of the springs k, k, and receiving plugs adapted to be inserted between the springs
of each pair to connect the line-circuit-strips with the connecting-strips.
I make each line-circuit-strip capable of separation into two distinct parts at a
given point, and this is preferably accomplished by means of two springs 1, 1, in
each strip, said springs forming a part of the strip, and being attached to the board
and normally pressed together at their outer ends like the springs k, k, but unlike
the last named springs, they are entirely disconnected or insulated from each other
at their bases, so that when separated and insulated at their outer ends they
convert the strip to which they belong into two distinct parts having no electrical
connection.
The listening telephone T is included in a listening circuit composed of wires
or cords n, n', and means whereby one of the said wires may be connected to one
of the parts of the line-circuit-strips (when the same is broken) and the other wire
to the other part, thereby looping in the listening telephone and causing the entire
current to pass around through the listening circuit in passing through the line-
circuit-strip with which said circuit is connected.
The means for connecting the wires n, n¹, respectively with the parts of the line-
circuits are preferably composed of springs o, o¹, arranged between the springs Z, 1,
and normally separated from the latter and from each other at their outer ends,
as shewn in Figure 7, so that when forced outwardly the springs o, 1, and the
springs o¹,, will make contact, as shewn in Figure 8, all the springs o being
connected with each other and with the wire n by a strip or wire p, and all the
springs. o with each other, and with the wire n¹ by a strip or wire p¹ through
suitable binding posts q, q¹. The springs l, l, and o, o¹, are arranged opposite to a
listening or central office telephone strip g¹ on the front of the switch-board, which
strip is parallel with the connecting-strips g and has holes coinciding with the
spaces between the springs o, o¹, so that a plug P of insulating material inserted
in one of the said holes will first press the springs o, o¹, outwardly against the
springs 1, 7, and secondly separate the springs 1,, as shown in Figure 8. The line-
circuit-strips pertaining to the separated springs 1, 1, are thus broken or separated
into two parts neither having any electrical connection with the other excepting
through the listening circuit through which the entire current passes from one
part of the line-circuit-strip to the other. The operation is as follows:-When the
operator at the central office wishes to place his office telephone into a circuit he
passes the tapered plug P made of insulating material, as described, through the
hole in the metal listening strip g¹ corresponding to the circuit.
As the plug P is pressed into said hole its end strikes the inner surfaces of
the free ends of the springs o, o, causing them to separate and to press against
and separate the contact springs 1,, as shewn in Figure 8, the plug not necessarily
touching the springs l, V.
It will be seen that the path of a current from line h is now by springs 1, o',
strip p', binding post q¹, through the telephone binding post q, strip p, springs o
and I, thus looping the telephone into the circuit. This operation may be repeated
with every line wire that connects with the switch-board. By pressing apart the
springs o, o¹, as before described, before separating the springs l,, all liability of
causing clicking noises in the circuit is avoided, but if the springs 1, , were
separated before the springs o, o¹, touched them a "click" might be communicated.
Figure 9 shows a modification in which the plug used is composed of a body of
insulating material r and plates 8, 8¹, secured to opposite sides thereof. The
springs o, o', do not in this instance touch springs, l, the latter being separated
by the plug itself. The springs o, o³, are separated first, and then the springs 7, 11,
by the plugs. In this case the path of the current would be from line h to spring 1,
through plate 8 of the plug, spring o' through the telephone, spring o opposite
plate & to spring Z.
Another modification is shown in Figures 10 and 11, in which one terminal of
each line-circuit-strip at its separable point is composed of a fixed contact point t
and a spring u, and the other terminal is composed of a spring u' normally in

page_text: contact with the point t and insulated from the spring u by an insulating disc v, as
shewn in Figure 10; w represents a metallic strip extending across the board
parallel with the listening strip g¹, and forming a back contact for the spring u.
In this modification the operator's telephone is connected with the listening strip g¹
and with the strip w. A metallic plug P¹ is employed, and when it is pressed into
one of the holes of the listening-strip, it makes contact with the spring u³, separates
the latter from the point t, thus breaking the line-circuit-strip, and presses the
spring u against the strip w, as shown in Figure 11, thus looping in the operator's
telephone, so that the circuit will be through the spring u, strip w, telephone and
metallic plug P¹ to the spring u'. When the plug is withdrawn the spring u'
returns to the point t, and the spring u separates from the strip w, so that the
current passes directly through the line circuit. It will be readily seen that the
act of pulling out a plug puts the telephone out of circuit in a manner as free from
disturbance and annoyance to the circuit as when the plug was introduced.
Having thus fully described the said Invention, as communicated to me by my
foreign correspondents, and the manner of performing the same, I wish it under-
stood that I do not limit myself in the application of these devices to the particular
form of apparatus shewn and described, as my Invention may be readily applied to
other forms of apparatus, but I claim,―
First. In an automatic magneto-generator, a disc I normally held in electrical
contact by a spring G³ combined with a rotary shaft F¹, amd a sleeve thereupon
for moving said disc to break the contact; substantially as described.
Second. In an automatic magneto-generator, the shaft F, the spring G³, the
sleeve G, the cam-slot K, and the screw K¹, combined, arranged, and operating as
described.
Third. In a switch-board having line-circuit-strips, connecting-strips, and per-
forations extending through the said strips and the board for the connecting
plugs, all arranged as described, the contact-springs f, f, connected with the line-
circuit-strips and arranged in pairs, each pair coinciding with one of the said
perforations, and adapted to grasp a plug inserted therein, the springs of each pair
pressing against opposite sides of the plug, as set forth.
Fourth. In an electrical switch-board, the combination of a series of line-circuit-
strips, each composed in part of separable springs 1, 7, normally pressed together and
adapted to be separated to convert the strip into two distinct parts, the springs o, o¹,
arranged as shewn, with relation to the springs 1, ', and connected, as described, in
a listening circuit, and means for electrically connecting the springs 1, 1, respectively
with the springs o, o¹, to loop in the telephone of the listening circuit, as set
forth.
Fifth. In an electrical switch-board, the combination of a series of line-circuit-
strips, each composed in part of separable springs l, l, normally pressed together
and adapted to be separated to convert the strip into two distinct parts, the springs
o, o¹, arranged as shewn, with relation to the springs L, l', and connected in a
listening circuit, as described, and a removable plug P of insulating material
adapted to be inserted between the springs o, o³, and thereby first make contact
between the springs o, l, and o¹, 1, and secondly, separate the springs 1, 2, to break
the line-circuit-strip and loop in the telephone of the listening-circuit, as set
forth.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal this untoanth in.. of L