IMPROVEMENTS IN CIRCUITS AND APPARATUS FOR ELECTRIC TEMPERATURE AND PRESSURE INDICATORS
Year: 1883

page_text: ETTERS PATENT to William Phillips Thompson, Fel. Inst. P.A. of the
Liverpool and London Agency for Foreign Patent Solicitors, 6 Lord Street
Liverpool, in the County of Lancaster, Civil Engineer. for an Invention of
IMPROVEMENTS IN CIRCUITS AND APPARATUS FOR ELECTRIC TEMPERATURE
AND PRESSURE INDICATORS"-A communication from Robert Hewett jr aud
Charles L Clarke persons resident at the city of New York in the county
and state of New York, United States of America
PROVISIONAL SPECIFICATION left by the said William Phillips Thompson
at the Office of the Commissioners of Patents on the 27th January 1883.
WILLIAM PHILLIPS THOMPSON, Fel. Inst. P.A. of the Liverpool and London
Agency for Foreign Patent Solicitors 6 Lord Street Liverpool in the county of
Lancaster Civil Engineer "IMPROVEMENTS IN CIRCUITS AND APPARATUS FOR
ELECTRIC TEMPERATURE AND PRESSURE INDICATORS "-A communication from
Robert Hewett jun., and Charles L. Clarke, persons resident at the city of New
York, in the county and State of New York, United States of America.
The invention relates to certain improved methods and apparatus for indicating
at any required station, variations in temperature or in the pressure exerted by
fluids, gases, or volatile substances at distant points.
The invention comprises an organization of apparatus located at the point where
the variations which are to be indicated occur, and adapted to transmit through
suitable conductors, successive electric impulses of a character and frequency depen-
dent upon the nature and extent of the variations occurring in the temperature or
pressure. At the receiving station is placed an organization of apparatus actuated
by the successive impulses transmitted through the main line conductors to indicate
the frequency and extent of the variations.
The invention contemplates the adaptation of the apparatus to both open and
closed electric circuits and to either one or two line wires connecting the transmitting
with the receiving station.

page_text: The transmitting devices comprise generally, either a suitable device responding
to variations in temperature, or a pressure gauge, adapted to actuate a circuit-
closing arm in one direction or the other, accordingly as the actuating power is an
increase or a diminution in the temperature or pressure to which the thermostatic
device or the pressure gauge is subjected. When the arm is actuated in one
direction, an electric impulse is transmitted upon one of the main lines, where two
are employed, for each predetermined space passed over by the circuit-closing arm.
When the circuit-closing arm, is moved in the opposite direction, impulses are
transmitted in like manner upon the second line wire.
In case only one line wire is employed electric impulses of one polarity are
transmitted upon the line wire by the movement of the circuit-closing arm in one
direction, and impulses of the opposite polarity by its movement in the reverse
direction.
The recording or indicating apparatus at the receiving station comprises two
systems of electro-magnets, one of which systems is vitalized by currents trans-
mitted over one line wire, and the other system by currents transmitted
over the other line wire. Or, in case currents of opposite polarity are trans-
mitted over a single conductor, the circuit is closed through one system of
magnets, when it is of a given polarity, and through the other when of the opposite
polarity. The electro-magnets are in either case provided with suitable devices for
causing an index hand to indicate upon a graduated scale or dial, the movements
of the circuit-closing arin, through the agency of which the impulses are transmitted.
In the circuit-controller which is placed at the station; the temperature of which
it is desired to be observed; a glass tube holds a column of mercury, upon which
rests a platinum float, which moves up and down according to the expansion or
contraction of its supporting column of mercury. Above the float the glass tube is
expanded into a bulb, which preferably contains a quantity of dilute sulphuric acid,
the office of which is to prevent the contact of the air with the float and mercury.
A fine wire and cord are mechanically connected with the float, the cord passing
over and connected with a small pulley. This pulley is attached to an arbor,
which moves with the least possible friction, in its bearings. To the same arbor is
attached a pointer, which reaches which reaches and sweeps over the face of the
graduated arc, and is in constant electrical contact therewith by means of a contact
wheel, which turns freely in its bearings, and rolls across the graduated portions of
the scale.
The graduated are is of metal, and is insulated from the frame of the instrument
by an insulating block to which it is attached. The indented lines which form the
graduations of the scale, are filled with suitable insulating material flush with the
surface. It will be understood therefore, that as the float is pushed upward by the
expansion of the column of mercury, the cord is loosened, and the preponderant weight
of the end of the pointer will cause it to fall, and wind the slackened cord around the
pulley. Near the bearings of the pulley and pointer is pivoted a second arm,
having its bearing in the base-plate of the instrument. This arm is counterbalanced
by a small weight, and it carries two insulated wires attached to two contact pins,
at its outer end. The arm of the pointer passes between these contact pins.
having a little space for free play. When therefore the pointer moves in either
direction, the second arm is almost immediately taken and carried along with it.
The indicating mechanism at the home or recording station, consists of two
electro-magnets, provided with armatures; a wheel, having a number of teeth or
notches upon its periphery equal to the number of divisions upon the graduated
arc or scale of the receiving instrument. An index or hand is affixed to the arbor
of the notched wheel, and moves over a graduated circular dial having the same
number of divisions as the before mentioned graduated arc. A T-shaped standard
projects from the back plate of the instrument, and furnishes bearing supports for
the notched wheel and the levers attached to the armatures of the electromagnets.
One end of a coiled spring is attached to the standard, and its other end to the face
of the notched wheel, and by its tension tends to turn the latter together with its

page_text: attached hand or index to the left, or towards 10 on the scale, but the wheel and
index are kept in check by a spring pawl and also by the pallet attached to a lever
or arm. A spiral spring tends to keep the pallet engaged with one of the teeth of
the wheel. If now a current of electricity passes through the coils of one of the
electro-magnets, its armature which is normally held against an adjustable stop by
a spring, is attracted towards the poles of the magnet, and a pallet on the armature-
lever is carried downward ready for engagement with a tooth of the notched wheel.
At the same time a pin upon the upper part of the armature-lever raises the before
mentioned arm and its pallet out of engagement with the wheel; while the other
end of the armature lever forces the spring pawl also out of engagement with the
notched wheel. The latter being thus released is carried forward by the stress of
the coiled spring through a space equal to one tooth, and is then stopped by its
engagement with the pallet on the armature lever. When the current ceases, the
armature is drawn away from the poles of the electro-magnet by the spring, until
arrested by the stop, the spring and pallet fall into their normal places and the
wheel is locked in its new position. Each to-and-fro movement of the armature
therefore, allows the index to be carried forward over one division on the graduated
dial.
If now a current of electricity passes through the other electro-magnet, its
armature is attracted and a lever and arm connected thereto are raised, and the
pallet on end of said arm is brought into engagement with the next upper tooth on
the notched wheel. When the current ceases, the armature is returned to its place
of rest against a stop by a spring, the arm and pallet are pressed downwards,
turning the wheel the space of one tooth in a reverse direction, and holding it there
against the stress of the coiled spring. Hence the two electro-magnets when
excited, respectively cause the index arin to move in opposite directions around the
graduated dial.
The electric circuit is arranged in the following manner. The battery has one
of its poles connected by a wire with the earth, and the other with the binding
post of the circuit controller, thence a wire leads to the graduated arc or scale--
From the scale the current passes by the contact-roller to the pointer, and the latter
being otherwise insulated, it passes to one of the contact pins in the arm which
moves with the pointer. It is evident that if the contact roller rests upon one of
the insulated portions of the scale, or if the pointer stands midway between the
contact-pins, no current will pass; but as the pointer moves downward, it impinges
upon one of the contact-pins, and the circuit is completed through the wire attached
thereto to a binding post, thence by another wire to a binding-post of the indicating
instrument. It then passes through the coils of one electro-magnet, after which it
goes to the earth. Therefore as the contact-roller advances over each successive
division of the graduated arc, the circuit through the electro magnet is alternately
opened and closed, and the index hand of the indicator will advance in like manner
over a corresponding number of divisions of the dial. Should the mercury in the
tube descend, then the weight of the float causes the pulley to turn, and with it the
pointer, which thus sweeps upward, carrying with it, the arm and contact pin. As
the pointer touches the contact-pin, the electric-circuit is made by a wire to another
binding post, and thence to a second binding-post on the indicating instrument,
whence it goes through the coils of the second electro-magnet, and so on to the
earth. Therefore as the contact-roller passes in a retrograde direction over each
successive division of the graduated arc, the circuit through the second electro-
magnet is opened and closed, and the index hand of the indicator will move over
a corresponding number of divisions of the dial in the opposite direction or towards
zero.
The apparatus which has been described for actuating the movable arm and
circuit-closer by the expansion and contraction of mercury, constitutes a ther-
mometer, and may be constructed in any well-known or convenient manner.
By substituting for the thermometric device hereinbefore described, any suitable
barometric apparatus, the organization may readily be adapted to indicate the

page_text: presence and pressure of gases in collieries, and in this connection will be found
of special importance. The same application may also be made of the apparatus to
be described.
The ther-
Referring now to the second method of carrying out the invention.
mostatic instrument which it is preferred to employ, consists of two curved
bimetallic strips, each of which is secured at the outer extremity to the frame.
The inner extremities of these strips extend in opposite directions upon opposite
sides of the trunnion or arbor of a double armed lever. In each arm of the lever
is formed a longitudinal groove or slot, through which slots project two pins,
respectively carried at the free ends of the thermostatic strips. Upon one arm of
the lever is formed a toothed segment concentric with the arbor. The teeth of
this segment engage a pinion formed upon an arbor upon which is carried a
pointer or index for indicating upon a dial the movements of the thermostatic
strips.
Upon the arbor carrying the small pinion and pointers and moving therewith, is
a circuit-closing arm carrying at its extremity two contact points.
This arm is preferably insulated from the arbor by an intervening ring or
An annular lug
sleeve of hard-rubber or other suitable non-conducting material.
formed upon the arm and in electrical connection with the contact points encircles
the arbor, and against this lug impinges a contact-brush.
The function of the arm is to close an electric circuit when moved through a
To accomplish
predetermined distance by the action of the thermostatic strips.
this end two contact-arms are mounted upon the insulating sleeve surrounding
a portion of the arbor. One arm is secured directly to the sleeve by means of a
collar or annular lug, and the other arm is in like manner mounted upon an insu-
At the extremities of these
lating sleeve surrounding the lug of the first arm.
arms are two contact-points situated upon opposite sides of the circuit-closing arm,
The contact points are
and in the same plane with the contact-points thereon.
moreover in electrical connection through their respective arms and annular lugs
These brushes are
upon their pivoted extremities, with two contact brushes.
normally placed in electrical connection through two relay magnets with one pole
of a battery, the opposite pole of which is in 'electrical connection with the contact-
points on the circuit closing arm. Que brush is normally in electrical connection
through conductors, movable armature-lever, and pendent contact-arm (hereinafter
to be described) with one pole of a battery. The other contact-brush is likewise
connected through a conductors armature-lever and peudent contact-arm with the
same pole of the battery. The opposite pole of this battery is connected through
a conductor with a third contact-brush, and thus with the contact points on the
circuit closing arm; when therefore this arm is moved into contact with either of
the other arms before mentioned, the circuit of the battery will be closed through
the corresponding system of conductors. The closing of this circuit serves both to
transmit an impulse over one or the other of two main line conductors leading to
a distant station; accordingly as the contact is made with one or the other of the
two arms, and immediately acts to move one of these arms, as the case may be, out
of contact with the circuit closing arm, and the other arm an equal distance in
the same direction. The first of these ends is attained by including in the con-
ductors two electro-magnets, the armature-levers of which are respectively
connected by conductors with the pole of the battery which is connected with the
circuit closing arm. The armature levers are provided with front contact springs,
from which they are normally held away by a retractile spring uniting the two.
The front contact springs are electrically connected by conductors with the main
lines. These electro-magnets act thus as relays to transmit impulses to the distant
station, whenever the circuit of the battery is closed through one or other of
the arms.
For the purpose of securing a reliable contact between the armature-levers and
.their respective contact springs, the latter are made extremely delicate and flexible,
and are provided with adjustable back contact stops, away from which they are

page_text: normally held by virtue of their resilience. When the armature-levers are drawn
toward their electro-magnets, they first make contact with their respective springs,
which are deflected by the further movement of the armature-levers until brought
into contact with the back contact stops. For the purpose of preventing the jar
which would be incident to the sudden arrest of the movement of the armature-
levers, and a consequent imperfect contact of the points, the contact-stops are
preferably provided with rubber buffers, consisting of short pieces of rubber
tubing, surrounding and projecting slightly beyond the extremities of the same.
The second object, namely, that of moving the contact arms correlatively with
the circuit-closing arm is accomplished through the agency of a second pair included
in the conductors, leading from the contact springs to the main lines. These
second pair of electro-magnets are provided with armatures mounted upon suitable
levers, carrying as extensions the movable armature-lever before referred to. The
armature-lever carries at its extremity a pawl, supported upon a flexible spring, and
preferably insulated from the lever by an intervening block of non-conducting
material. This pawl extends toward the periphery of the ratchet wheel, rigidly
mounted upon but insulated from the sleeve on the central arbor. The teeth of this
wheel are inclined in such a manner as to allow the pawl to slide freely over them
when the armature lever is drawn toward its electro-magnet. When however the
electro-magnet is demagnetized, and the lever is being drawn away from its poles
by a retractile spring, the pawl will engage one of the teeth of the ratchet-wheel,
and cause it to be turned through a portion of a revolution, determined by the
amplitude of the vibration of the armature-lever. This is determined by suitable
adjusting stops applied to the extremity of the extension. In practice it is prefer-
able to adjust the movements in such a manner that the wheel will be revolved
through the distance occupied by one of its teeth, by each vibration of the
armature-lever.
For the purpose of interrupting the circuit at the relay contact-spring, when the
electric impulse shall have accomplished its several objects, namely, that of
vitalizing the electro-magnet, and actuating its armature-lever so that the pawl
shall engage a tooth upon the ratchet wheel, and also of actuating the recording or
indicating device at the distant station, the device hereinafter described is provided
for interrupting the actuating circuit of the relay electro-magnet, immediately after
the vitalization of the other electro-magnet. The extension of the armature lever
of the electro-magnet is provided with an adjustable contact-point, against the
extremity of which rests, by virtue of gravity, a contact-point carried upon a
pendent arm near its lower extremity. The arm is loosely supported upon a pivot
in such a manner, that it will normally rest against the contact-point with sufficient
pressure to form a good electrical connection. When however the electro-magnet
is vitalized, and its armature-lever thereby actuated, the movement of the extension
of this lever will convey to the pendent arm, a sufficient impetus to carry it beyond
the limit of the vibration of the former, and thus interrupt the connection between
the contact-points. The circuit through the relay electro-magnet will thus be
broken, and its armature-lever will be drawn away from the contact-spring, thus
interrupting the circuit through the conductor and electro-magnet. Before the
circuit is again closed by the point on the pendent arm falling against the contact
point on the extension of the armature-lever, the armature-lever itself will have
been withdrawn from the poles of the magnet, and the contact arms carried a
sufficient distance to place the first out of contact with the circuit-closing arm,
and the second at approximately the same distance from the arm upon the opposite
side.
For the purpose of operating the contact-arms in the reverse direction, when the
movement of the circuit-closing arm is in the opposite direction and toward the
right, a second electro-magnet is included in the conductor, and provided with an
armature and armature-lever carrying a pawl, supported upon a spring, which
several elements are counterparts of the corresponding ones already described. A
second ratchet-wheel is also rigidly mounted upon the sleeve, but insulated there-

page_text: from and constructed to be revolved by the pawl in the reverse direction in the
same general manner as the wheel already described. For this purpose the teeth
of this wheel are inclined in an opposite direction from those of the other wheel.
The armature-lever of the electro-magnet also carries an extension which is
provided with a contact-point, and pendent arm carrying a contact point, all similar
in operation and construction to the corresponding parts employed in connection
with the other electromagnet-Their mode of operation does not therefore require
further explanation.
For the purpose of preventing the contact-arms from moving at other times than
when actuated by one or the other of the electro-magnets, a serrated wheel having
the same number of teeth as each of the ratchet wheels is rigidly mounted upon the
sleeve and insulated therefrom. The teeth of this wheel are wedge shaped and
against its periphery is lightly pressed a dog carried upon a yielding support. While
the pressure of this dog is sufficient to prevent an accidental displacement of the
wheel and its sleeve in either direction, it will not afford any appreciable
hindrance to the movement of the same under the action of either of the pawls.
At the distant or indicating station is provided an index-hand, mounted upon an
arbor, and constructed to be moved in either direction in front of a dial, correla-
tively with the movements of the thermostatic index, a result which is effected
through the agency of the following named instrumentalities: Two electro-magnets
are respectively included in the circuits of the main lines. After traversing the
coils of these magnets the conductors are connected with the earth. The pole of
the battery not connected with the main lines is also united with the earth.
One of these electro-magnets is provided with an armature, and armature-lever
carrying a spring-pawl. This pawl is constructed to engage the teeth of a ratchet-
wheel while the lever is receding from the poles of the magnet. The wheel is
rigidly mounted upon the arbor. At the cessation of each impulse transmitted over
the line, this arbor will be turned through the distance occupied by one of its
teeth.
The other electro-magnet is likewise provided with an armature and armature
lever and spring pawl. A second ratchet-wheel is mounted upon the arbor, and
constructed to actuate the same in the reverse direction, through the influence of
successive impulses transmitted through the main line and electro-magnet. Thus
the index hand will be moved in one direction or the other, correlatively with the
movements of the circuit-closing arm and will thus cause the temperature at the
transmitting station to be indicated by its position upon the dial. A check-wheel,
provided with a spring-pawl similar in construction to the device employed for the
same purpose at the transmitting station, may be mounted upon the arbor to
prevent accidental displacement of the index-hand.
In the organization of apparatus herein before described, it is necessary to employ
two main line conductors for connecting the transmitting with the receiving
apparatus. In a modification of the invention the apparatus is adapted to be
operated by a single main line conductor. In this organization a polarized relay
is employed for transmitting to line, a current of one polarity or the other
according to the direction of motion of the thermostatic device, and at the
receiving station a second polarized relay for determining in which direction the
recording device shall be actuated. In organizing the apparatus for this purpose,
substantially the same system of thermostatic and primary circuit-closing devices
is employed as already described. Instead of a single battery however, it is
preferable to employ two batteries or battery-sections, opposite poles of which are
connected with the earth. The remaining poles of these batteries are respectively
connected through conductors with two contact-brushes. These brushes are
respectively in contact with two insulated annular lugs formed at the pivoted
extremity of the circuit-closing arm and these lugs are respectively electrically
connected with two insulated contact-points carried at the extremity of that arm.
The contact arms are in electrical connection through conductors respectively with
the extensions of the armature-levers respectively as in the former instance. The

page_text: pendent arms however, are electrically connected by conductors through the coils
of a polarized relay, and thus with the main line. The armature is normally held
by two springs midway between two contact-springs, respectively connected by
conductors with the poles of the batteries, which are in electrical connection with
the contact points at the extremity of the circuit-closing arm. Each of the springs
work against a contact-stop, out of contact with which they are normally
maintained by their own resiliency. The contact-points are respectively connected
by conductors through the coils of the electromagnets, and by means of a conductor,
common to both, with the main line. The construction of the polarized relay is
such, that an impulse from the battery traversing its coils to the line, will cause
the armature to be impelled toward the left, carrying one spring into contact
with its stop.
A current from the battery however will actuate the armaturo
in the opposite direction carrying the other spring into contact with its stop.
At the receiving station the same system of apparatus is employed for actuating
the indicating device as described in the former instance, but instead of connecting
the main line through the electro-magnets, a polarized relay is included in the
main line which is connected with the earth. The electro-magnets are included in
branch conductors leading from a conductor connected with the main line to the
contact-stops of the armature of the polarized relay. The armature is electrically
connected by a conductor. It is normally maintained, by suitable springs at a
point midway between these contacts. A negative current however from the line
traversing the coils of the polarized relay, will cause the armature to impinge
against one contact-stop, and will thus close the branch circuit of the main line.
Upon the cessation of this impulse, the index will be actuated toward the left
hand in a manner already sufficiently described. The effect of a positive current
from the line will be precisely similar with the exception that the other
electro-magnet will be vitalized and the index will be actuated in the reversed
direction.
A modification of the pendent-arms and their attendant devices may be
arranged with reference to the main and local circuits, which consists in interposing
the same in the main line circuit. The line for this purpose, is connected directly
with the pendent arm, and the contact brush is connected with the conductor
leading to the electro-magnet, while the line is connected with extension of the
armature-lever. In like manner the second main line is connected with the other
pendent arm with the conductor leading to the other electro-magnet. The
conductor is connected with the extension of the armature of this magnet
A still further modification in the same direction as that last indicated consists
in applying the pendent arms to the armature-levers of the receiving instrument,
and interrupting the main circuit in the manner last described.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Phillips Thompson in the Great Seal Patent Office on the
27th July 1883.
WILLIAM PHILLIPS THOMPSON Fel. Inst. P.A., of the Liverpool and London
Agency for Foreign Patent Solicitors, 6, Lord Street, Liverpool in the County of
Lancaster, Civil Engineer, "IMPROVEMENTS IN CIRCUITS AND APPARATUS FOR
ELECTRIC TEMPERATURE AND PRESSURE INDICATORS."-A communication from
Robert Hewett Jun., and Charles L. Clarke, persons resident at the city of New
York, in the county and state of New York, United States of America.
The invention relates to certain improved methods and apparatus for indicating
at any required station variations in temperature or in the pressure exerted by
fluids, gases, or molatile substances at distant points.
The invention comprises an organization of apparatus located at the point where
the variations which are be indicated occur, and adapted to transmit through
suitable conductors successive electric impulses of a character and frequency
dependent upon the nature and extent of the variations occurring in the temperature
or pressure. At the receiving station is placed an organization of apparatus actuated
by the successive impulses transmitted through the main line conductors, to indicate
the frequency and extent of the variations.
The invention contemplates the adaptation of the apparatus to both open and
closed electric circuits, and to either one or two line wires connecting the trans-
mitting with the receiving station.
The transmitting devices comprise generally, either a suitable device responding
to variations in temperature, or a pressure gauge, adapted to actuate a circuit-
closing arm in one direction or the other accordingly as the actuating power is an
increase or a diminution in the temperature or pressure to which the thermostatic
device or the pressure gauge is subjected. When the arm is actuated in one
direction an electric impulse is transmitted upon one of the main lines, where two
are employed, for each predetermined space passed over by the circuit-closing arm.
When the circuit-closing arm is moved in the opposite direction, impulses are
transmitted in like manner upon the second line wire.
In case only one line wire is employed electric impulses of one polarity are
transmitted upon the line wire by the movement of the circuit-closing arm in one
direction, and impulses of the opposite polarity by its movement in the reverse
direction.
The recording or indicating apparatus at the receiving station comprises two
systems of electro-magnets, one of which systems is vitalized by currents transmitted
over one line wire and the other system by currents transmitted over the other
line wire. Or, in case currents of opposite polarity are transmitted over a single
conductor, the circuit is closed through one system of magnets, when it is of a
given polarity, and through the other when of the opposite polarity. The electro-
magnets are in either case provided with suitable devices for causing an index-
hand to indicate upon a graduated scale or dial, the movements of the circuit-
closing arm through the agency of which the impulses are transmitted.
In the accompanying drawings two organizations of circuits and apparatus for
carrying out the invention are illustrated. Fig. 1, Sheet I, is a front elevation
of a device for transmitting impulses through one or the other of two electric
conductors, correlatively with the movements of a circuit-closing arm actuated in
correspondence with thermal variations, together with a device for indicating the
same. Fig. 2, Sheet 1 is a vertical section of the transmitting device. Figs. 3

page_text: and 4, Sheet II, are respectively a front and a side elevation of a transmitting
device for transmitting impulses correlative with the variations in temperature
upon a normally open circuit. Fig. 5, Sheet II, is a theoretical diagram illustrating
the method of organizing the circuits for conducting the impulses to an indicating
device, which device is also illustrated in connection with the diagram. Fig. 6,
Sheet III, is a theoretical diagram illustrating the invention as applied to apparatus
designed to transmit and indicate thermal variations through the medium of a
single electric conductor. Fig. 7, Sheet III, illustrates certain details in the
construction of the device shown in Fig. 6. Fig. 8, Sheet III, illustrates a modifi-
cation in the organization of the apparatus illustrated in the diagram Fig. 5.
Referring to figs. 1 and 2, (Sheet I), A represents the circuit-controller which
is placed at the station, the temperature of which it is desired to be observed;
and B represents the indicating device placed at the recording or observing
station.
The glass tube a holds the column of mercury, upon which rests a platinum
float b, which moves up and down according to the expansion or contraction of its
supporting column of mercury. Above the float b the glass tube is expanded into
the bulb c which preferably contains a quantity of dilute sulphuric acid, the office
of which is to prevent the contact of the air with the float and mercury. A fine
wire d and corde are mechanically connected with the float, the cord passing over
and connected with the small pulley f (best seen in fig. 2). This pulley f is
attached to the arbor f¹, which moves with the least possible friction, in its
bearings f² and ƒ³, the former in the base plate of the instrument, the latter in an
arm or projection f screwed thereto. To the same arbor, f', is attached the hand
or index g which reaches and sweeps over the face of the graduated arc h, and is
in constant electrical contact therewith by means of the contact wheel g', which
turns freely in its bearings, and rolls across the graduated portions of the scale.
The graduated arch is of metal and is insulated from the frame of the instrument,
being attached to and supported by the insulating block. The indented lines
which form the graduations of the scale are filled with suitable insulating material
flush with the surface, as shown at h² (fig. 2). It will be understood therefore,
that as the float is pushed upward by the expansion of the column of mercury, the
cord e is loosened and the preponderant weight of the end of the arm g will causo
it to fall and wind the slackened cord around the pulley f. Near the bearings of
the pulley fand arm g, is pivoted a second arm i, having its bearing in the base-
plate of the instrument, turning on its arbor with the least possible friction.
The arm is counterbalanced by the weight 2, and it carries two insulated wires
attached respectively to the contact-pins 3 and 4, at its outer end. The arm g
passes between these contact pins, having a little space for free play. When
therefore the arm g moves in either direction, the arm i is almost immediately
taken and carried along with it.
The indicating mechanism at the home or central Station consists of two electro-
magnets M and M', provided with armatures m and m'; a wheel, W, having a
number of teeth or notches upon its periphery equal to the number of divisions
u on the Scale h. An index or hand kc is affixed to the arbor of the wheel W, and
moves over the graduated circular dial n, having the same number of divisions as
the scale h. The T-shaped standard T projecting from the back plate of the
instrument, furnishes bearing supports for the wheel W, and the armature-
levers m² and m³ of the electro-magnets M and M'. One end of a coiled spring s
is attached to the standard T and its other end to the face of the wheel W, and
by its tension tends to turn the latter together with its attached hand or index k
to the left, or towards 10 on the scale, but the wheel and index are kept in check
by the spring-pawl p, and also by the pallet r, which is attached to the arm t.
The spiral spring & tends to keep the pallet r engaged with one of the teeth of
the wheel W. If now a current of electricity passes through the coils of the
electro-magnet M, the armature m, which is normally held against the stop v by
the spring is attracted towards the poles of the magnet, and the lower left end

page_text: of the curved armature lever m² which forms a pallet m³ is carried downward
ready for engagement with a tooth of the wheel W. At the same time a pin y upon
the upper part of the armature lever m² raises the arm t and its pallet r out of
engagement with the wheel W, while the other curved lower extension m¹ of the
armature lever m², forces the spring pawl p also out of engagement with the
wheel W. The latter being thus released is carried forward by the stress of the
springs through a space equal to one tooth, and is then stopped by its engage-
ment with the pallet m³. When the current ceases, the armature m is drawn
away from the poles of the electro-magnet M by the spring s³, until arrested by the
stop v, the spring p and pallet fall into their normal places, and the wheel W is
locked in its new position. Each to-and-fro movement of the armature m, there-
fore, allows the index k to be carried forward over one division on the graduated dial n.
If now a current of electricity passes through the other electro-magnet M',
the armature m¹ is attracted, the armature lever m³ and connecting arm t are
raised, and the pallet is brought into engagement with the next upper tooth.
When the current ceases, the spring draws the armature up against the stop v',
the arm t and pallet are pressed downwards, turning the wheel W the space of
one tooth in a reverse direction and holding it there against the stress of the
coiled spring 8. Hence the two electro-magnets M and M¹ when excited,
respectively cause the arm k to move in opposite directions around the graduated
circle n.
The operation of the apparatus is as follows: The arm g being properly con-
nected with the float b so as to point to the mark o or zero, on the scale h, when
that corresponds to the temperature of the column of mercury; then with any
expansion of the column and rise of the float b, the arm g will fall, and the
wheel g' will roll downward across the graduations of the scale h, first meeting
with the contact pin ³ and then carrying along with it the arm i
The electric circuit is arranged in the following manner: The battery E has
one of its poles connected by a wire 1 with the earth at G, and the other with the
binding post P; thence a wire 2 leads to the graduated are or scale . From the
scale the current passes by the contact-roller g¹ to the arm g, and, the latter being
otherwise insulated, it passes to one of the contact-pins or . The method of
connecting the two wires to the contact-pins 3 and 4, and of insulating them from
each other, is shown in fig. 2. It is evident that if the contact-roller g' rests upon
one of the insulated portions of the scale h, or if the arın y stands midway between
the contact-pins i³ and i¹, no current will pass; but as the arm g moves downward
it impinges upon the contact-pin and the circuit is completed through the wire 3
to the binding post C, thence by wire 4 to binding post H of the indicating
instrument B. It then passes through the coils of the electro-magnet M, after
which it goes to the earth at G¹ by the wire 5. Therefore as the contact-roller g¹
advances over each successive division of the scale h, the circuit through the
electro-magnet M is alternately opened and closed, and the hand k of the indicator
will advance in like manner over a corresponding number of divisions of the
scale n.
Should the mercury in the tube descend, then the weight of the float
causes the pulley f to turn, and with it the index g, which thus sweeps upward,
first meeting the contact-pin and then carrying upward along with it the arm i.
As the index g touches the contact pin 4, the electric circuit is made through the
wire 6 to the binding post C¹, and thence by wire 7 to the binding post H³, of the
indicating instrument, whence it goes through the coils of the electro-magnet M¹
and so by wire 5 to the earth at G'. Therefore as the contact-roller gl passes in
a retrograde direction over each successive division of the scale h, the circuit
through the electro-magnet M' is opened and closed, and the hand k of the
indicator will move over a corresponding number of divisions of the scale n in the
opposite direction or towards zero.
The apparatus which has been described for. actuating the movable arm and
circuitcloser by the expansion aud contraction of mercury, constitutes a thermo-
meter, and may be constructed in any well-known or convenient manner.

page_text: By substituting for the thermometric device hereinbefore described, any suitable
barometric apparatus, the organization may readily be adapted to indicate the
presence and pressure of gases in collieries, and in this connection will be found of
special importance. The same application may also be made of the apparatus to
be described.
Referring now to the second method of carrying out the invention as illustrated
in figs. 3, 4 and 5 (Sheet II). A represents a suitable case for enclosing, and B a
frame for supporting the various parts of the thermostatic and the impulse trans-
mitting devices. The thermostatic instrument which it is preferred to employ,
consists of two curved bi-metallic strips B' and B2, each of which is secured at the
outer extremity to the frame B. The inner extremities of these strips extend in
opposite directions upon opposite sides of the trunnion or arbor B³ of a double
armed lever B'. In each arm of the lever B' is formed a longitudinal groove or
slot B5, through which slots project two pins B6 Be respectively carried at the free
ends of the thermostatic strips B' and B'. 'Upon one arm of the lever B is formed a
toothed segment B7 concentric with the arbor B³. The teeth of this segment
engage a pinion B8 formed upon an arbor B°, upon which is carried a pointer or
index B for indicating upon a dial B the movements of the thermostatic strips.
The operation of this portion of the instrument is as follows: Any change of
temperature will cause the thermostatic strips to assume a more or less curved
position and their free ends will thereby be carried simultaneously in opposite
directions, thus causing the lever B to be moved in one direction or the other
through the agency of the pins B and slots B5. This motion is communicated by
the segment B7 and pinion B³ to the arbor B and index B¹º.
Upon the arbor B' and moving therewith is a circuit-closing arm C carrying at
its extremity two contact points c c.
The arm C is preferably insulated from the arbor B by an intervening ring or
Sleeve of hard-rubber or other suitable non-conducting material. An annular
lug d formed upon the arm C and in electrical connection with the points c
encircles the arbor B9; and against this lug impinges a contact-brush D.
The function of the arm C is to close an electric circuit when moved through a
predetermined distance by the action of the thermostatic strips. To accomplish
this end, two contact-arms C and C² are mounted upon the insulating sleeve E
surrounding a portion of the arbor B. The arm C is secured directly to the
sleeve E by means of a collar or annular lug e and the arm C¹ is in like manner
mounted upon an insulating sleeve e³ surrounding the lug e of the arm 02. At
the extremities of these arms are two contact-points c¹ and c² respectively situated
upon opposite sides of the contact-arm C, and in the same plane with the contact
points c. The contact points c¹ and c³ are moreover in electrical connection,
through their respective arms and annular lugs e upon their pivoted extremities,
with two contact-brushes e¹ and e³ respectively. These brushes are norinally
placed in electrical connection through two relay magnets with one pole of a
battery, the opposite pole of which is in electrical connection with the contact
points c c. The brush e is normally in electrical connection through a conductor 2,
a movable armature lever f', and pendant contact-arm g₁ (hereinafter to be
described), and conductors 3 and 4, with one pole of a battery O. The contact-
brush is likewise connected through a conductor 5, arınature-lever f³ and
pendent contact arm g³, which are counterparts of the lever f¹ and arm g', and
conductors 6 and 4 with the same pole of the battery O. The opposite pole of
this battery is connected through a conductor 1 with the contact-brush D, and
thus with the contact-points c. When therefore the arm C is moved into contact
with either of the arms C or C2 the circuit of the battery will be closed through
the corresponding system of conductors. The closing of this circuit serves both to
transmit an impulse over one or the other of two main line conductors L or L¹
5 leading to a distant station accordingly as the contact is made with one or the
other of the two arms C¹ or C2, and immediately acts to move the arm C or C³, as
the case may be, out of contact with the arm C and the other arm an equal distance

page_text: in the same direction. The first of these ends is attained by including in the
conductors 3 and 6 respectively, two electro magnets H₁ and H³, the armature
levers h¹ and h² of which are respectively connected by conductors 7 and 9, and 8 and 9
with the pole of the battery O which is connected with the contact arm C. The
armature levers h' and h² are respectively provided with front contact springs h³ and h
from which they are normally held away by a retractile spring S uniting the two.
The springs h³ and h are respectively electrically connected by the conductors 10
and 11 with the main lines L and L. These electro-magnets act thus as relays to
transmit impulses to the distant station whenever the circuit of the battery O is
closed through one or the other of the arms C' or C².
For the purpose of securing a reliable contact between the armature lovers h¹
and 2 and their respective contact springs h³ and h, the latter are made extremely
delicate and flexible and are respectively provided with adjustable back contact-
stops and h", away from which they are normally held by virtue of their resilience.
When the armature-levers are drawn toward their electro-magnets they first make
contact with their respective springs, which are deflected by the further movement
of the armature-levers, until brought into contact with their respective back
contact-stops. For the purpose of preventing the jar which would be incident to
the sudden arrest of the movement of the armature levers and a consequent
imperfect contact of the points, the contact-stops h¹0 and h¹ are preferably provided
with rubber buffers h¹ and 13 consisting of short pieces of rubber tubing
surrounding and projecting slightly beyond the extremities of the same.
The second object, namely, that of moving the contact arms C and C² correla-
tively with the circuit-closing arm C, is accomplished through the agency of two
electro-magnets F1 and F2, respectively included in the conductors 10 and 11
leading from the contact springs 3 and h to the main lines Land L. The electro-
magnets F1 and F are respectively provided with armatures F3 and F4 mounted
upon suitable levers F5 and F°, carrying the extensions f¹ and f³ before referred to.
The armature lever Fs carries at its extremity a pawl k¹ supported upon a flexible
spring and preferably insulated from the lever by an intervening block k³ of
non-conducting material. This pawl extends toward the periphery of a ratchet
wheel E rigidly mounted upon, but insulated from the sleeve E. The teeth of
this wheel are inclined in such a manner as to allow the pawl to slide freely over
them when the armature-lever F is drawn toward its electro-magnet. When
however the electro-magnet is demagnetized and the lever is being drawn away
from its poles by a retractile spring s¹, the pawl will engage one of the teeth of
the ratchet-wheel and cause it to be turned in the direction indicated by the
arrow y through a portion of a revolution determined by the amplitude of the
vibration of the armature-lever. This is determined by suitable adjusting stops t¹
and applied to the extremity of the extension f¹. In practice it is preferable to
adjust the movements in such a manner that the wheel E' will be revolved through
the distance occupied by one of its teeth, by each vibration of the armature lever.
It will be evident from the above explanation, that through the influence of
successive impulses transmitted through the conductor 10 upon the main line L,
the ratchet wheel E' and consequently the sleeve E carrying the contact arms C₁
and C, may be revolved in the direction indicated by the arrow y¹. As already
stated, such an impulse will be transmitted whenever the circuit-closing arm C is
placed, by the action of the thermostat, in electrical connection with the contact-
arm C. The movement however will not be imparted to the ratchet-wheel E' and
arm Cuntil the cessation of the impulse so transmitted and the consequent
retraction of the armature-lever F5.
For the purpose of interrupting the circuit at the relay contact-spring ³ when
the electric impulse shall have accomplished its several objects, namely, that of
vitalizing the electro-magnet F" and "actuating its armature lever so that the
pawl ke shall engage a tooth upon the ratchet wheel E', and also of actuating the
recording or indicating device at the distant station, the device hereinafter
described is provided for interrupting the actuating circuit of the relay electro-

page_text: The
magnet H', immediately after the vitalization of the electro-magnet F'.
extension f¹ of the armature-lever F³ is provided with an adjustable contact
point g, against the extremity of which rests, by virtue of gravity, a contact
point g carried upon the pendent arm g¹ near its lower extremity. The arm g¹ is
loosely supported upon a pivot g', in such a manner that it will normally rest
against the contact point g² with sufficient pressure to form a good electrical con-
nection. When however the electro-magnet F¹ is vitalized and the lever F³ thereby
actuated, the movement of the extension f¹ will convey to the pendent arm gla
sufficient impetus to carry it beyond the limit of the vibration of the the former,
and thus interrupt the connection between the points g2 and 95. The circuit
through the relay electro-magnet will thus be broken and the armature-lever h¹
will be drawn away from its contact-spring h³, thus interrupting the circuit through
the conductor 10 and electro-magnet Fl. Before the circuit is again closed by the
point g falling against the point g², the armature lever Fs will have been
withdrawn from the poles of the magnet F, and the arms C1 and C2 carried a
sufficient distance in the direction indicated by the arrow y¹ to place the former
out of contact with the arm C, and the latter at approximately the same distance
from the arm C upon the opposite side.
For the purpose of operating the contact arms C and C² in the reverse direction
when the movement of the circuit-closing arm C is in the opposite direction and
toward the right, a second electro-magnet F is included in the conductor 11, and
provided with an armature F and armature-lever Fs carrying a pawl ko supported
upon a spring k, which several elements are counterparts of the corresponding
ones already described in connection with the arm C-A second ratchet wheel E
similar to the ratchet wheel E, is also rigidly mounted upon the sleeve E, but
insulated therefrom and constructed to be revolved by the pawl in the direction
indicated by the arrow 2 in the same general manner as the wheel E¹. For this
purpose the teeth of this wheel are inclined in an opposite direction from those
of the wheel E'. The armature lever Fo also carries an extension f³, which is
provided with a contact-point g* and pendent arm g³ carrying a contact-point go,
all similar in operation and construction to the corresponding parts employed in
connection with the electro magnet F¹. Their mode of operation does not therefore
require further explanation.
It will now be evident that when the circuit closing arm C has been moved
through a predetermined distance, say that corresponding to the fraction of a
revolution, arbitrarily chosen to indicate a degree of temperature upon the dial B",
an electric impulse will be transmitted from the battery O upon one or the other
of the two main line conductors L and L¹, accordingly as the arm C is actuated
toward the right or left. At the transmitting station the apparatus will imme-
diately operate to interrupt the circuit and re-adjust the contact-arms to the new
position of the circuit closing arm by moving them simultaneously in the direction
of the motion of the latter through an arc represented by one degree. This
operation is repeated for each degree or division of the dial passed over by the
circuit-closing arm,
For the purpose of preventing the contact-arms from moving at other times than
when actuated by one or the other of the electro-magnets F1 and F, a serrated
wheel Es having the same number of teeth as each of the ratchet-wheels E' and E,
is rigidly mounted upon the sleeve E and insulated therefrom. The teeth of this
wheel are wedge-shaped, and against its periphery is lightly pressed a dog E*
carried upon a yielding support E³. While the pressure of this dog is sufficient
to prevent an accidental displacement of the wheel and its sleeve in either direction,
it will not afford any appreciable hindrance to the movement of the same under
the action of either of the pawls ' or .
At the distant or indicating station is provided an index-hand P mounted upon
an arbor P and constructed to be moved in either direction in front of a dial P3,
correlatively with the movements of the therinostatic index B10, a result which is
effected through the agency of the following named instrumentalities: Two

page_text: electro-magnets M₁ and M² are respectively included in the circuits of the main
lines Land L. After traversing the coils of these magnets the conductors L and
A conductor 12
L' are connected with the earth at G¹ by means of a conductor 13.
also unites the pole of the battery O not connected with the main lines, with the
earth at G.
The electro-magnet M' is provided with an armature m¹ and armature-lever m²
carrying a spring-pawl n similar in construction to the pawl k¹. This pawl is
constructed to engage the teeth of a ratchet wheel N¹ while the lever m² is
receding from the poles of the magnet M¹. The wheel N' is rigidly mounted upon
the arbor P'. At the cessation of each impulse transmitted over the line L, this
arbor will be turned in the direction indicated by the arrow z¹ through the distance
occupied by one of its teeth, in the same general manner as described with reference
to the ratchet wheel E¹.
The electro-magnet M2 is likewise provided with an armature m³ and armature
lever m and spring pawl n². A second ratchet-wheel N2 is mounted upon the
arbor P¹ and constructed to actuate the same in the direction indicated by the
arrow z through the influence of successive impulses transmitted through the main
line L' and electro-magnet M². Thus the index-hand will be moved in one
direction or the other correlatively with the movements of the circuit-closing
arm C, and will thus cause the temperature at the transmitting station to be
indicated by its position upon the dial P2. A check-wheel N³ provided with a
spring-pawl N, similar in construction to the device employed for the same purpose
at the transmitting station, may be mounted upon the arbor P¹ to prevent accidental
displacement of the index-hand P.
In the organization of apparatus herein before described it is necessary to employ
two main line conductors for connecting the transmitting with the receiving
apparatus. In fig. 6 a modification of the invention is shown, whereby the
apparatus is adapted to be operated by a single main line conductor. In this
organization a polarized relay is employed for transmitting to line a current of one
polarity or the other, according to the direction of motion of the thermostatic device
and at the receiving station a second polarized relay for determining in which
direction the recording device shall be actuated. In organizing the apparatus for
this purpose substantially the same system of thermostatic and primary circuit
closing devices is employed as already described. Instead of a single battery O
however, it is preferable to employ two batteries or battery-sections O¹ and O³,
opposite poles of which are connected with the earth at G2 by conductors 15
and 16. The remaining poles of these batteries are respectively connected through
conductors 17 and 18 with two contact-brushes D1 and D2. These brushes are
respectively in contact with two insulated annular lugs d' and d² (see fig. 7) formed
at the pivoted extremity of the circuit closing arm C, and these lugs are respec-
tively electrically connected with two insulated contact-points c³ and c¹ carried at
the extremity of that arm. The contact-arms C and C are in electrical connec-
tion through the conductors 2 and 5 respectively with the extensions f' and ƒ³
respectively as in the former instance. The pendent arms g' and g³ however, are
electrically connected by conductors 19 and 20 through the coils of a polarized
relay H³ and thus with the main line L². The armature is normally held by two
springs and 85 midway between two contact-springs h° and h, respectively
connected by conductors 21 and 22 with the poles of the batteries O' and O² which
are in electrical connection with the contact points c³ and c. Each of the springs he
and h works against a contact-stop, as shown at 8 and hº, out of contact with
The contact
which they are normally maintained by their own resiliency.
points 8 and h³ are respectively connected by the conductors 10 and 11 through
the coils of the electro-magnets F¹ and F2, and by means of a conductor 25, common
to both, with the main line L. The construction of the polarized relay H³ is such
that an impulse from the battery O' traversing its coils to the line L will cause
the armature h³ to be impelled toward the left, carrying the spring h° into
contact with the stop 8. A current from the battery O' however will actuate the

page_text: cure 76 in the opposite direction, carrying the spring into contact with
the stop h³
Assuming the arm C to be moved toward the left and the contact-point ca to be
placed in connection with the contact point c¹, the circuit will be closed from the
battery Othrough the conductor 17, contact-brush D¹, contact-point c³, contact-
aru C, contact-brush el, conductor 2, extension f¹, pendent arm g', conductor 19,
and polarized relay H³ to the line L. The armature 5 will thereupon be actuated
and the spring he be caused to impinge against the contact stop 18, thereby closing
the circuit from the negative pole of the battery O¹ through the conductors 21
and 10, electro-magnet F¹, and conductor 25 to the main line L. The armature-
lever F5 will accordingly be actuated, and the circuit through the polarized relay H³
will be interrupted by the movement of the pendent arm g¹, in the same manner
as in the organization first described. The armature h³ will in consequence assume
its normal position and the circuit through the electro-magnet F¹ will also be
interrupted. The subsequent retraction of the armature-lever Fs will actuate the
ratchet wheel E' and arins C1 and C2 as in the former instance.
When the circuit is closed by the movement of the arm C in the opposite
direction, that is toward the right-hand, the operation will be precisely similar, the
circuit of the battery being closed from its positive pole through the polarized
relay H and then through the electro-magnet F2, causing the arms C and C² to
be moved in the corresponding direction. Thus it will be evident that negative or
positive impulses will be transmitted upon the line L2 to the distant station
according to the direction of motion of the arm C.
It
At the receiving station the same system of apparatus is employed for actuating
the indicating device as described in the former instance, but instead of connecting
the main line L2 through the electro-magnets M1 and M2, a polarized relay M is
included in the main line which connected with the earth at G³ by a conductor 26.
The electro-magnets M1 and M2 are respectively included in branch conductors 27
and 28, leading from a conductor 29 connected with the main line to the contact-
stops me and m² respectively, of the armature m³ of the polarized relay M. The
armature m is electrically connected by a conductor 30 with the earth at G³.
is normally maintained, by suitable springs 86 and 87 at a point midway between
these contacts. A negative current however from the line L2 traversing the coils
of the polarized relay M will cause the armature to impinge against the contact-
stop me, and will thus close the branch circuit of the main line through the
conductor 27 and electro-magnet M¹ to the contact-stop me, thence through
the armature m³ and conductor 30 to the earth at G³. Upon the cessation of
this impulse, the index P will be actuated toward the left-hand in a manner already
sufficiently described. The effect of a positive current from the line L2 will be
precisely similar, with the exception that the electro-magnet M² will be vitalized
and the index P will be actuated in the reverse direction.
In fig. 8 a modification is shown in the arrangement of the pendent-arms g¹
and g and their attendant devices, with reference to the main and local circuits,
which consists in interposing the same in the main line circuit. The line L, for
this purpose, is connected directly with the arm g', and the contact brush e¹ is.
connected through the conductor 2 with the conductor 3 leading to the electro-
magnet H¹, while the line 10 is connected with the extension fl of the armature
lever F. In like manner the main line L' is connected with the pendent arm g³,
and the conductor 5 with the conductor 6 leading to the electro-magnet H³. The
conductor 11 is connected with the extension f³. The operation will be essentially
the same, with the exception that in this organization, the circuit of the main line
being first interrupted, the discharges of the magnets F and H' will be manifested
at the point g³, but being in opposite directions will tend to neutralize each other;
and the discharge of the electro-magnet H' will be manifested at the point c¹,
whereas in the first described organization, the entire tendency of the discharges
will be to manifest themselves at the points g³ and h³, and no discharge will occur
through the more delicate point c.

page_text: A still further modification in the same direction as that last indicated consists
applying the pendent arms to the armature-levers m³ and m' of the receiving
trument, and interrupting the main circuit in the manner last described.
Having thus described the nature of this invention, and the manner the same is
be performed, as communicated to me by my foreign correspondents, I would
e it understood that I claim
The combination, substantially as hereinbefore set forth, of a thermometer, an
electric generator, a contact arm movable to and fro by the expansion and
contraction of said thermometer, a series of contacts corresponding in number
to the arbitrary divisions of the thermometric scale, a common conductor to
which all the said contacts are united, two movable contact-stops, upon one
or the other of which the said contact-arm impinges, according to the direction
of its movement, two main conductors respectively extending from said
movable stops to an observing station, an electro-magnet in each of said main
conductors at said observing station, and an index, the movements of which
in one direction or the other, are controlled by the action of the respective
electro-magnets.
The combination, substantially as hereinbefore set forth, of a normally open
main circuit, an automatically operated circuit-closing arm, a local circuit
closed by the operation of said arm, an electro-magnet included in said local
circuit, acting, while vitalized, to close said normally open main circuit, and a
second electro-magnet acting to temporarily interrupt said local circuit when
said main circuit is closed.
The combination, substantially as hereinbefore set forth, of a normally open
main electric circuit, an automatically operated circuit-closing arm, a local
circuit closed by the operation of said arm, an electro-magnet included in said
local circuit, acting, while vitalized, to close said main circuit, an electro-
magnet included in the main circuit, an armature and armature-lever actuated
by the last named electro-magnet, and a pendent arm actuated through the
movement of said armature-lever to temporarily interrupt said local circuit.
The combination, substantially as hereinbefore set forth, of an automatically
operated circuit-closing arm, a contact-arm extending in proximity to said
circuit-closing arm, an electro-magnet, its armature and armature-lever, means
substantially such as described for successively closing and interrupting an
electric circuit through the coils of said electro-magnet through the instru-
mentality of said circuit-closing and contact-arms, a pawl carried upon
said armature-lever, a ratchet-wheel engaged by said pawl for moving said
contact-arm out of contact with said circuit-closing arm when the circuit
through said electro-magnet is interrupted.
The combination, substantially as herein before set forth, of a circuit-closing arm
automatically revolved in either direction, two contact-arms, one adjacent to
each side of said circuit-closing aru, means substantially such as described,
for transmitting electric impulses to a distant station correlatively with the
movements of said circuit-closing arm, and means substantially such as
described for revolving both of said contact-arms in the direction of the
motion of said circuit-closing arm when said impulse has been transmitted.
In witness whereof I tbe said Willian Phillips Thompson have hereunto set
y hand and seal this tenth day of July in the year of our Lord one thousand
ht hundred and eighty three.
D
HANDSON