IMPROVEMENTS IN ELECTRICAL CALL OR SIGNAL APPARATUS "FOR TELEGRAPHIC 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 CALL OR SIGNAL APPARATUS "FOR
TELEGRAPHIC AND TELEPHONIC PURPOSES." A communication from abroad
by David Hall Rice and Jacob B. Currier, both of Lowell, Massachusetts,
United States of America.
.
.1
..
COMPLETE SPECIFICATION filed by the said William Robert Lake at the
Office of the Commissioners of Patents on the 20th April 1881.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent
Agents, Southampton Buildings, London. "IMPROVEMENTS IN ELECTRICAL': CALL
OR SIGNAL APPARATUS FOR TELEGRAPHIC AND TELEPHONIC PURPOSES." A, com-
munication from abroad by David Hall Rice and Jacob B. Currier, both of Lowell,
Massachusetts, United States of America.
This Invention relates, firstly, to improvements in electric calling and alarmn
devices to be placed upon telegraphic or telephonic circuits or lines to call 'and
sound an alarm at any one of a number of stations on such circuit without calling
and alarming any other station upon the said circuit.
'
To this end the first part of the said Invention comprises the employment upon.
such telegraphic or telephonic lines, for the purpose of ringing alarms or calls; of
vibrating springs or reeds, which are graduated so as to vibrate at given normal
rates of oscillation, and an undulatory or broken electric current synchronous with
the reed or spring to be actuated, each of the said reeds on a circuit being different
froin every other, and each being placed at a different station on the said circuit,
and operating directly or intermediately upon the bell or alarm mechanism.'
The objects of this part of the said Invention are to provide a device or
mechanisin which shall give a satisfactory alarm at any desired station on an
electric circuit without sounding an aların at any other station; to provide such
mechanism as shall permit of a considerable number of alarms being upon one
TD 017
'

page_text: circuit without danger of sounding any of the alarms except the one desired, and
one by which such increased number will not increase the difficulty and labor of
the operator in managing the circuit, and to provide automatic stop-mechanism
which shall hold and operate the calling or caller mechanism with precision.
These objects are obtained by the mechanism illustrated in Figures 1 to 4 of the.
accompanying Drawings, in which
Figure 1 is an elevation, partly in section, of my improved telegraphic alarm or
alarm-device; and
Figure 2 is a plan of the same.
Figure 3 is a front elevation of the caller or calling device.
Figure 4 represents an ordinary electric circuit provided with its ground
connection and battery, and having different stations thereon at which are placed a
series of aların devices or apparatuses, and a central or calling station at which is
placed a calling device constructed according to this Invention.
In Figure 4, W, Y, W, represent the electrical circuit; 0, 0, are its ground-
connections, and Z is the battery; 1, 2, and 3" are the stations at which the
different alarm-devices are placed, and 4* is the central or calling station at which
the calling device is placed. These stations may be at any convenient distance
apart upon the circuit. The details of the alarm and calling devices are shewn
most clearly in Figures 1, 2, and 3, and are hereinafter described.
It has long been known that when elastic steel tongues are fixed in proper
position with relation to electro-magnets in a circuit, they may be set in vibration
if magnetized by currents of electricity to which an undulatory or intermittent
motion over the circuit is given, provided such undulations correspond in number
in a given time with the normal rate of vibration of such congue or tongues to be
affected. It has further been demonstrated by Helinholtz and. others that when
two or more steel tongues, differing in their normal rate of vibration in a given
time with their magnets, are introduced in the same electric circuit, the intermittent
or undulatory electric current which will set one of such magnetized tongues in
vibration will leave the other practically unaffected, and vice versa, provided the
difference in their normal rate of vibration is considerable, because the steel
tongues are of considerable rigidity and sufficient to resist undulations in the
electric current not in or approximating closely to their normal vibration
respectively. According to the first part of this Invention I employ a modification
of such vibrating tongues by making them somewhat more slender than those
employed as above mentioned, and providing them with a ball or hammer at the
end, and placing a bell in proper position to be struck thereby. According to this
part of the said Invention also I place such tongues in relation to their magnets
which vibrate them, and to the strength of the electric current which develops the
attractive power of the said magnets, so that no single electric impulse will draw
the tongue up to the magnet and thereby cause currents, not in the normal time of
vibration of a tongue, to make it strike the bell. I also attach to the steel tongue
opposite to the magnet a soft iron armature where interimnittent currents of the
same polarity are to be used to vibrate it, and I also place one of these alarm
devices or instruments at each of the separate or different stations on the electric
circuit which are to be called, the alarin mechanism of each station being so
constructed as to require a different time of undulation or vibration of the electric
current to operate it from that of other stations on the line. I also provide
improved adjusting mechanism for setting the vibrating tongue in proper position,
as above described with relation to its magnet and bell.
The said Invention moreover comprises improvements in the mechanism for
making and breaking the electric circuit to effect the putting in operation in the
most efficient manner of the above described alarm-inechanism. Practically my
improved alarm mechanism differs from a steel tongue without a hammer attach-
ment in its capacity of striking a louder and better aların at the station desired, and
it differs from a bell hammer which is operated by a magnet, and swings freely
upon an axis or pivot to and from the bell in preserving its normal rate of vibration

page_text: while continuing to strike the bell at each oscillation. It has been found that this
is not the case with a bell-hammer swinging freely, because one or two strokes
upon the bell by the latter tend to throw it out of its normal rate of vibration, and
so cause its strokes upon the bell to grow weaker or cease entirely from the
As above stated,
interruption of its synchronous action with the electric current.
this is not the case with the spring-striker above mentioned; this fact may be
attributed to the resilient power of the spring, which immediately overcomes the
Another
tendency of the blow upon the bell to interrupt its synchronous action.
advantage of the spring-striker is the extreme rapidity with which it can be set in
action and the rapidity with which it delivers its blows upon the bell. This not
only produces a better alarm, but enables the placing of a greater number of such
aların-devices, operating at a varied rate of speed or in different time upon the same
circuit.
Referring to the Drawings, S₁ is the base-board upon which is secured the
cylinder 6; this cylinder has a dial-pointer and a dial d, upon which are figures
indicating the different stations upon the circuit. Attached to the said cylinder by
one of its ends is a spring-strip of metal g, considerably longer than the circum-
ference of the cylinder, and upon the pendant end of the said strip is placed a bob f
of such weight that the resiliency of the metal strip acting as a vibrating tongue
will be able to quickly overcome any momentum which can be given it, so that
when it is started swinging back and forth like a pendulum, instead of swinging
with the slowness of a true pendulum, or nearly so, it will by its spring-like action
make many more vibrations in a given period of time. The addition of the bob f
to the spring genables the time of vibration of the spring to be altered by merely
shortening or lengthening the same without necessarily varying its resiliency, as
might be required if the bob were not attached.
W represents the wire connecting the battery with the insulated plate ; into
this plate the stud h, upon which the cylinder b is rotated, is inserted. Y is the
line passing from the insulated screw out to the different stations and aların
instruments or devices upon the circuit. m is an arın swinging in the path of the
weight and having attached to it a spring n sufficiently strong to overcome the
gravity of the weight fand the resilience of the suspending spring g. This spring g
will therefore be constantly held in a state of tension against the screw k by the
arın m, and the electric current will be free to pass through the plate l, stud h,
cylinder b, spring-strip g, and screw k to the line Y.
When however the arm m is swung out of the way of the weight, by bearing
quickly upon the thumb-piece x so as to bring the arm over to a suitably arranged
pin, the gravity of the weight f and the resilience of the spring strip 9 will cause
the weight to follow after the said arın. The bob or weight being small in pro-
portion to the power of the spring, it will as it swings beyond the perpendicular
have its momentum quickly overcome by the strength of the spring, and begin its
backward movement, and will thus commence a series of rapid vibrations, which,
with a proper proportioning of the spring-strip and weight, may be made, to reach
several hundred
and as the circuit is broken each time the spring-strip
minute;
per
leaves the screw each time the weight vibrates, the circuit will be made and
broken. I am thus enabled to greatly increase the number of electric impulses upon
a circuit in a given time, and consequently a larger number of alarm devices can be
placed upon a circuit and still have the difference between any two of the said
devices marked by the same or a greater number of separate movements per second
than before. This results from the fact that a certain difference in the number of
their vibrations-in a given time must exist between the strikers of different stations
in order that the caller when sending a number of electric or magnetic impulses over
the line in a given time, corresponding with the vibrations of one striker, shall not
operate the other strikers on the line which are nearer in times of vibration to the
one actuated. This difference in the number of vibrations of the several strikers is
as effectual to accomplish this, whether the vibrations themselves are comparatively
slow or fast, within certain limits.

page_text: When it is desired to increase or diminish the number of times the circuit is made
and broken in a given period, the vibrating spring-pendulum is either shortened or
lengthened, as the case may be by, rotating the cylinder which winds or unwinds the
spring upon itself.
In Figure 1, S represents a base-board, which is attached to a wall or to some
convenient object; C, D, and E, represent supports for the vibrating striker, an
electro-magnet, and a bell; these are made adjustable, as shewn, or in any other
convenient manner. Extending from the adjustable rod N held by the support C
is the vibrating spring-tongue F, which has attached to it opposite the poles of the
electro-magnet A an armature G, and opposite the bell B the bob or hammer H
held in place upon the tongue by the set screw h*. This vibrating tongue F is of
such a stiffness and is placed at such a distance from the electro-magnet, that its
attached arinature will be far enough from the magnet to ensure that no single
impulse of any current, which is ever allowed to pass over the line, will bring thei
together or cause the hammer to strike the bell either when continued for a long
or a short period of time, but it is at such a distance that the armature will be
drawn, while the circuit is complete, a considerable distance toward the magnet,
moving the spring-vibrating tongue from its point of rest until the resistance of the
spring and the force of the magnet are in equipoise. This adjustment is made
either by changing the distance between the point of attachment of the vibrating
tongue and the base-board, or by placing the mechanism in such a position that
the action of gravitation will bring the armature nearer to the magnet when at
rest. This construction and relation of the armature and the vibrating striker F, H,
is essential to the operation of the said Invention for the reason that it enables the
oscillations of strikers, which are not vibrating in unison with the magnetic or
electric impulses to obtain a return movement when first attracted, which operates
against the electric impulses instead of in unison with them, and thus to prevent
their aların being sounded, at the same time it enables the oscillating striker which
is vibrating in unison with the electric or magnetic impulses over the line to
re-inforce the attractions created in the magnet by such impulses, and thus actuate
its alarm with certainty and effect.
The spring-striker F is secured to the sliding bolt N by the screw L. This
bolt N slides in a hole in the support or brace C which forms a sleeve, and the
lower end of the said bolt N bears upon a spiral spring which tends to press it out
of the said sleeve. The spring-striker F with its sliding bolt N is adjusted and
secured in position by a screw K passing through a lug or projection of the sleeve C,
as shewn.
The hammer H is arranged to slide upon the spring F, and is secured in position
with reference to the bell B by means of the set-screw /* as above stated. The
bell B is attached to a plunger T which slides in the bore of the stud or support E.
A set-screw V passing through a lug upon this stud E serves to adjust the bell to
and from the spring-hammer with relation to the latter and the magnet A. These
several parts permit the setting or adjustment of the hammer, the bell, and the
magnet, in their proper relative positions to accomplish the best result, which
adjustment is of great importance.
Having arranged a number of alarm-devices at different stations upon a circuit,
all adjusted so that no two having vibrating tongues of the same stiffness, length,
and weight of hammer, or an aggregate of these elements which shall be the same,
the operation of the device may be thus described.
By a sudden release from the position in which it is held by a stop as the
extreme of its arc of movement, the pendulumn-weight and spring-tongue of the
caller makes and breaks the circuit moving on account of the acclerating action of
its spring-suspending strip with great celerity for a limited length of time, the bob
being set at such a length that it will vibrate in the period of the vibration of
some one of the alarm movements upon the circuit; the circuit being made and,
broken and a number of alarms being upon it, they will after being attracted (each'
with its first breaking) fall back with their vibrating tongues and hammers towards

page_text: their normal position of rest, being acted upon by the resiliency of their spring-
vibrating tongues. By the momentum gained as the hammers or bobs move
toward such normal position, they will be carried beyond such position and then
will return. Now if the circuit be again made and broken at the time one of the
vibrating tongues begins to swing back towards the magnet, that one will by the
acceleration which it receives by the attraction of the magnet upon its armature
swing nearer to the magnet than at first, because of the momentum its hammer has
gained; when if the circuit be continued to be broken and made at proper intervals
of time corresponding to the vibration of the bob or hammer, its motion will
continue to be increased until the armature finally comes in contact or nearly so
(dependent on adjustment) with the poles of the electro-magnet at each vibration,
when the bob or hammer will repeatedly strike the bell with considerable force, for
the reason that the power of the electro-magnet upon the armature is much greater
when the armature comes close to it. If however the circuit be not made and
broken in the proper and regular intervals corresponding to the vibrations of the
spring-tongue carrying the hammer or bob, its motion will be adverse to the
attraction of the magnet, and it will not strike its bell, as the attraction of
the magnet will so frequently be exerted while the armature and hammer are
swinging away from and in opposition to the said magnet, and the vibratory
movement will be constantly checked instead of accelerated.
Now as the different alarms placed upon the circuit have their spring-tongues of
such a length and stiffness, and are provided with hammers so adjusted that no
two of them will make a complete vibration in the same period of time, it is
evident that but one alarm will be struck or sounded by any regular making and
breaking of the circuit, and that by making and breaking the circuit a number of
times in the period of vibration of any one of the alarm-spring-tongues, such alarm
will be struck. To ensure the striking of but one alarm it is desirable that a
number of impulses be requisite before the haminer will reach the bell and the
adjustment of the vibrating tongue, magnet, armature, and bell is so effected that
such will be the case.
It will be understood that the striking of the bob upon the alarm-bell is not a
necessary part of this Invention, as the vibration of the tongue may be made to
sound an alarm in a great variety of ways by intermediate mechanism, such as
clockwork, auxiliary batteries and circuits, and the like.
The spring alarm devices herein described can be used with the spring-hammer
in any convenient position, as for instance, projecting horizontally or at any angle
to the perpendicular, and this will be found very convenient in many cases.
It is also obvious that instead of using a closed circuit an open one may be
employed, and it is also obvious that the device may be made to operate on a circuit
with a very strong electric or magnetic force, even if the circuit be not entirely
broken; if it be very largely increased and diminished it can be made to operate
substantially as would a weaker current made and broken if the aların mechanism
be adjusted for the purpose.
My improved circuit-breaker makes and breaks the circuit by direct contact
and without intervening mechanism, and the part of the circuit with which it
comes in contact forms the axis of its movement during part of its beat. This
construction avoids friction and allows of a more efficient and longer continued
action of the circuit-breaker. The circuit-breaker also has the stop mechanism or
lever mi to set it in motion, which lever is held against it as shown. By pressing
upon the thumb-piece of the said lever the spring-bob fis released and set in
motion.
This Invention relates, secondly, to electric calls or calling devices placed upon
telephonic or telegraphic circuits, the object of this part of the said Invention
being to provide such switch-mechanism as will permit of a call being made upon
any one of a number of stations without sounding the call bell of any other of the
stations upon the circuit.

page_text: This object is accomplished by the mechanism illustrated in Figures 5 and 6 of
the Drawings, in which—
Figure 5 represents a single electric switch with its short circuit and alarm-
mechanism connected therewith, and
Figure 6 represents a main circuit having thereon a series of separate stations,
at each of which is placed one of my improved electrical switches for shifting or
shunting the electrical current from the main circuit to the short circuit of such
station; this view also represents a calling station provided with means for
switching the electrical current upon the short circuit of any desired station and
sounding the alarm thereof.
In these Figures A', A, represent the main circuit, M its battery, and G, G, the
ground-connections; N is a rheostat or resistance-coil; 1ª, 2, and 3*, represent the
separate stations on the line to be called, which stations may be any distance
apart; C represents the calling station; 1, 2, 3b, represent devices for making
and breaking the circuit corresponding respectively in synchronism with the
vibrating tongues of the switches at the different stations to be called; f, f, f,
represent the short circuits of the stations to be called, with each of which is
connected, as shewn, a cominon electrical bell, each short circuit being grounded
at G. The devices for making and breaking the circuit at the station C' are of
ordinary construction.
A, A', is the line-wire coming from the central office and connecting with other
stations out upon the line; B is a vibrating tongue attached to the metal block b
through which the circuit passes to the electro-magnet C; from this magnet the
circuit passes to the wire connecting with the next station. This tongue B is of
such a length and so adjusted that its vibration is made in a given period of time,
and the tongues of the different instruments upon the line A, A¹, are of such
different lengths and adjustments that no two of them have the same period of
vibration or so nearly the same period as to both be made to vibrate norinally by
electric impulses over the line corresponding to the normal vibration of one of the
two. D is a spring placed above the vibrating tongue attached to the block h;
this spring is connected by the wire f with another electro-magnet which operates
a bell S and has a ground-connection G. The tongue B consists of a soft iron
armature arranged opposite the magnet C and attached to a steel blade; the said
tongue is adjusted at such a distance from the electro magnet C as to be sensibly
attracted by it without being brought into contact therewith by any single
attraction which the magnet may exert. The spring D is placed a sufficient
distance from the tongue so that no vibration of the tongue caused by a single
electric impulse and attractive action of the magnet C will bring them in contact
while it is still within the path of the normal vibration of the tongue in its given
time.
Upon the spring and tongue are placed points n of platinum or other metal
which come in contact when the vibration of the tongue is sufficient. The spring d,
being shorter and lighter than the vibrating tongue b, makes many more vibrations
than the tongue when struck by it, and will therefore make a frequent and
prolonged contact with the said tongue.
When the contact is made between the spring D and the vibrating tongue B, the
circuit will be complete through the wire f, spring y, and hammer-rod k, to the
electro magnet / which has a ground-connection, and as this circuit is made to have
less resistance than that through the magnet C and line-wire A, the current will
pass through the said magnet l, which, acting upon its armature m, strikes the
bell S, and breaking the circuit by withdrawing or separating the points 8, upon
the spring g, and armature m from contact with one another, permits the armature
to fall back and again bring the point into contact and complete the circuit and
again strike the bell. This action will be continued as long as the tongue B
continues to vibrate into contact with the spring D.
Instead of connecting the line-wire with the blocks b, and permitting the circuit

page_text: t
to be made through the vibrating tongue B, the line-wire may be connected with
the block h, and the wire f, instead of being attached to the latter may be made
fast to the block of another spring whose bifurcated end abuts against the spring D,
so that when the said spring D is in a state of rest, the two will not be in contact,
but when the spring D is struck by the tongue B it will be made to vibrate in
contact the bifurcated ends of the spring connected with the bell-mechanisin, and
as the spring D and the bifurcated spring-end come in contact more frequently
than the vibrating tongue and the spring D, this modification may sometimes be
desirable.
When the points n are not in contact, the current will pass over the line-
wire A, A, through all the stations, each of which is provided with switch-mechanism
similar to that above described, except that no two of them have tongues whose
period of vibration is the same.
When the operator at the central office desires to call any one of the stations, he
makes and breaks the circuit a number of times in the time required to vibrate the
tongue B at the desired station, and with each electric impulse which passes over
the line the vibration of the tongue will be increased until its vibrations will
reach their normal limit and bring the point n upon it in contact with the point n
on the spring D, when the call bell S will be sounded as above described, but as
the tongues at the other stations upon the line do not vibrate in the same period
of time as that in which the current is made and broken, their movement will not
be accelerated to its normal point by their electro-magnets, and none of them will
vibrate sufficiently to bring themselves into contact with their like springs D and
no alarm will be sounded at any station other than the one being called.
It will be understood that I use at the calling station an automatic calling
device to make and break the electric circuit of suitable construction for operating
the switches and their attached call bells, such, for instance, as that described with
reference to the first part of this Invention, or of any other well known construction
of oscillating pendulum, vibrating reed, or rotating cylinder mechanism.
•
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
understood that I claim,-
First. The combination in an electric circuit of a vibrating spring-tongue,
actuating an alarm-device with a circuit-breaker which makes and breaks the
circuit in the time required to vibrate the tongue and actuate the alarin, substantially
as above described.
Second. The combination with their electro-magnets in an electric circuit of two
or more vibrating spring-strikers, placed at different stations in the circuit, each of
whose periods of vibration differs from that of the others and operates an alarm by
a suitable intermittent or vibrating electric current passing over the circuit
synchronously with the striker, operated substantially as herein described.
Third. The combination on an electric circuit of a number of vibrating alarm
spring-tongues placed at different stations therein and adapted to vibrate in
different periods of time with a vibrating circuit-breaker, capable of being adjusted
and operated to make and break the circuit with sufficient rapidity and in the
time of vibration of any desired one of the alarm spring-tongues, substantially as
above described.
Fourth. The electric aların-device consisting of the magnet A, the spring F, the
hammer H, and the bell B, constructed, combined, and adjusted, substantially as
herein described, that is to say, so that the hammer vibrates in a given time and is
not brought into such a position as to strike the bell by any single impulse of the
electric current and consequent attraction of the magnet, all substantially as above
set forth and for the purpose specified.
Fifth. The combination on an electric or magnetic circuit provided with suitable
mechanism for transinitting electrical or magnetic iinpulses thereover of two aların

page_text: devices placed at different stations, and each composed of the magnet A, the
spring F, the hammer H, and the bell B, the said springs and hammers being
constructed to vibrate in substantially different times, and all being constructed
and combined, substantially as above described.
Sixth. In combination with the vibrating spring-caller or circuit-breaker, the
pivotted stop m and its spring n, substantially as above described.
Seventh. The combination of the bell B, the electro-magnet A, the armature G,
and the spring bob or striker, the said "bell and striker being adjusted relatively to
the magnet, as above set forth, whereby the bell will not be sounded until the
intermittent attraction of the magnet is reinforced by several synchronous vibrations
of the striker, substantially as above described.
Eighth. In combination with the spring bob or striker F, H, adapted to vibrate
synchronously with an intermittent electric current, and its magnet A, and bell B,
the adjusting screw K, and sliding bolt N, substantially as herein described.
Ninth. In combination with the bell B, the magnet A, and the synchronously-
operating spring-hammer H, the set-screw V, adapted to adjust the bell, substantially
as above described.
Tenth. In combination with the electric circuit, the spring circuit-breaker with
its attached weight f, and the synchronously-operating spring-striker F, H, with
its magnet A, substantially as above described.
Eleventh. The combination of a main electrical circuit and two or more short
circuits f,f, by means of magnets C and vibrating tongues B, each. of which is
capable of vibrating in a different time from the other, and both of which are
capable when vibrating in their respective times of transmitting the electric current
from the main circuit A to the short circuits f, f, and sounding alarms thereon,
substantially as above described.
Twelfth. The combination of the main electrical circuit A with a circuit f by
means of the electro-magnet C and vibrating tongue B, so adjusted that the latter
is capable of transmitting the electric current to the circuit f when its vibrations
have been augmented by a number of synchronous electrical impulses through the
magnet, but is not capable of so transmitting the current by any vibration caused
by a single electrical impulse, substantially as herein described.
Thirteenth. The combination of the electro-magnet C, its vibrating tongue B
connected to the circuit, and the contact-spring D, all so adjusted and arranged
that a series of synchronous electrical impulses passing through the magnet C and
attracting the tongue B must be re-inforced by several synchronous vibrations of
the tongue to bring it into electrical contact with the spring D, substantially as
above described.
Fourteenth. In combination with each other, an electric battery, a telegraph line,
switch-mechanism, operated by regular intermittent impulses of the electric current
from a distant station to convey the latter upon a short or side circuit, and a call-
bell in the said short circuit, substantially as herein described.
Fifteenth. In combination with the vibrating reed, the spring D separated
therefrom when at rest, and arranged to vibrate inore rapidly than the said reed,
and the whole forming switch-mechanism to convey the electric current,substantially
as described.
Sixteenth. The combination on an electric circuit of a series of vibrating spring-
reeds B, B, each placed at a separate station on the circuit, and each constructed
of a substantially different tension or vibrating length and size, to vibrate in
unison with intermittent electrical impulses passing synchronously over the said
circuit with the magnets C and the bells S placed in like manner, the latter
constructed to operate by connecting mechanism from the said spring-reeds,
substantially as above described.
Seventeenth. In combination with the electric circuit, a vibrating circuit-breaker,
which makes and breaks the circuit to sound the alarms by direct contact.
Eighteenth. In combination with the electric circuit, a circuit-breaker vibrating

page_text: about or upon its make and break contact point during some part of its vibration,
substantially as described.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and Seal, this Twentieth day of April, in the year of our Lord One-
thousand eight hundred and eighty one.
W. KUB'. LAKE.
(L.S.)