US1253001A - Electric signal system. - Google Patents

Description

F. W. COLE.

' ELECTRIC SIGNAL SYSTEM.

APPUCATION FILED IUNE 29, I914- 1L ,Q53fl1 Patented Jan. 8,1918.

2 SHEETSSHEET 2.

.aeaaooi.

-:To all u'homit may concern:

} nnrrnn snares ra rnnr orrrcn FREDERICK W. COLE, NEWTON, MASSACHUSETTS, ASSIGNOR TO GAMEWELL FIRE ALARM TELEGRAPH COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

ELECTRIC SIGNAL SYSTEM;

Specification of Letters Patent.

Patented Jan. 8, rare.

Application filed June 29, 1914. Serial No. 847,891.

l 3e it known that I, FREDERICK WV CoLE,a citizen of the United States, residing at .Newton, in the county-of Middlesex and State. of Massachusetts, have invented, an Improvement in Electric Signal Systems, of

which theifollowing is a specification.

This invention relatesto an electric signalsystcm and is particularly adapted for use in connection with fire-alarm telegraph and similar systems. a

Fire-alarm telegraph systems, as commonly constructed, involve an electric signaling circuit, having connected therein a source of energy, and signal-transmitting means, arranged to open and close saidcirwit to transmit their signals, said means being normally in circuit-closing condition, and one or more signal-responding means, the controlling-magnets of which, or it may be relays, are connected in and responsive to the breaks and closures of the circuit.

In practice these fire-alarm systems must not be excessively expensive to maintain and must be reliable so as to correctly operate at any moment.

To insure this reliability, the circuits are normally closed inforderv that their condition may be known, and the signal responding means are arranged for operation upon the breaks. Any break of a circuit is therefore immediately announced, and hence the circuits are under continual automatic test.

To maintain low operating expense, firealarm systems are generally arranged to automatically transmit and announce their signals throughout a city, so that the expense of experienced operators continually on duty to attend to the signals and watch the condition of the system andcthe responding instruments therein, may be reduced to a minimum, and for best eiliciency, the signal announcing or responding instruments in such systems should be given as wide a margin of safety as possible for correct working.

The proportion of time that a fire-alarm telegraph system is actually used for fire signaling even in the largest cities is relatively very small indeed, yet it must be kept in proper signalingcondition at all times,

and heretofore the whole amount of current needed for actual signaling has been continually maintained on the circuits to attain such end.. 5 a l To keep this maintenance icostofncurren a the fire-signals or alarms cannot be promptly sent and correctly responded to, and the prompt sending of a correct fire-signal, which is the whole object of a fire-alarm telegraph system is defeated.

Signal responding and announcing instruments and other forms of signal-receiving instruments, all of which are herein included by the general term, signal respondingmeans, in fire alarm telegraph systems are controlled by the armatures of electro-magnets or relays, which magnets are included in, connected to, or controlled by, the electric circuits in such systems.

It is a well-known fact that much more current is required to energize an electromagnet to cause it to move its armature from its retracted position, which it assumes when the circuit is open, than is required to maintain it in attracted position after having been moved to such attracted position.

It therefore follows that the current re quired to operate thearmature of a respond ing instrument during signaling, which is done by repeatedly opening and closing the circuit, is much greater than is necessary to keep the circuit under continual test thereafter, when no signalis being sent and during which time the armatures simply remain attracted but are ready to instantly retract when the circuit is broken.

The discharge of battery and its cost of maintenance is, therefore, in practice, very much higher. than what it would be if the normal current maintained, while no signals are being sent, was only what was necessary to keep thearmature in attracted position.

In order to reduce the normal output of current to be maintained and thereby to re duce maintenance cost as much as possible, it is a common practice to have the fire-alarm circuits of as low resistance as possible and to this end low resistance line wires are used with joints carefully made and often soldered and the signal-transmitting means,

some of which are called signal boxes, are

provided with shunts which give a path of low resistance around the si naling-mechanisms and any magnets associated therewith when said mechanisms are not in use.

When such a signaling-mechanism isoppends upon the relative amount of resistance of the circuit at other times, to the amount so introduced, and therefore in a low resistance circuit on which the usual standard of current only is normally maintained the drop would be the greatest and the liability of loss of signals be the greatest in these circuits where most pains had been taken and expense incurred to have them of low resistance for efficiency, but which end was absolutely defeated by this fundan'iental principle.

It is also obvious that the constant test by keeping the circuit continually closed cannot always show by the signaling-instruments whether the line is in signaling condition from such fact, as the current might be strong enough to hold the armature attracted while the circuit remained close and notification would not be given, yetsuch current might not be strong enough to cause the responding means to respond properly if a signal was attempted to be sent.

The object of this invention isto provide an electric signal system with means an 'anged to act automatically upon the breaking of the circuit to insure a strong energizing or boosting current upon the closure thereof, in order that the magnets of the signal-responding means may respond promptly and correctly to the operation of the circuit, even under extremely unfavorable conditions, to materially increase the speed at which a fire alarm system may be operated, and to automatically prevent waste of batter while but a small normal current is required, and to reduce the normal maintenance, cost, and up-keep of the system while thus greatly increasing its ef ficiency. i

The invention is especially valuable in fire-alarm signaling circuits in which signalresponding means are scattered throughout a city or town where they cannot have con- -tinual manual attention, and in all signaling 5.

systems where it is vitally 'importantthat every operation of the circuit shall be correctly responded to.

By this invention the eiliciency ofthe circuit, when being used for the transmission of a signal can be automatically increased lo a point above normal standard to enable the signal responding means to have a greatermargin of safety in operating, thereby to respond promptly and correctly even though the current on the line under bad conditions would not have been enough otherwise to properly operate said signal responding means, andiit can be adjusted to give automatic notification long before the circuit is so bad as to prevent proper signaling; It reverses the usual conditions of signaling circuit andgives an increased current at the most vital-moment, and when most needed for emergencies It prevents liability of loss of signals under load or lowv battery conditions of the circuit,'it increases the speed at which signals may be correctly and properly sent, received, interpreted and announcechand gives an efiiciencylong desired. The cost of its introduction into a circuit will be many times paid for inia short time by the saving of battery that its use will allow for the reason thatthe invention enables the normal currentmaintained to be even less than the standard current and yet at the moment of operation of assignal-mechanism will automatically provide that the current shall even 'beeabove the standard, which is the moment when 'most needed. J i i i In the embodiment of my invention, here shownfor illustration, a resistance, preferably non-inductive, isnormally included in the circuit to keep the normal discharge of the battery low and means are employed for shunting said resistance upon a break of the circuit, so that upon a-subsequent closure thereof an'increased strength of the current is then immediately temporarily available, due to the less resistance in the circuit and which will cause the magnets of the signal-responding means included in or connected with the circuit to be charged promptly, so that their armatures will be moved quickly thereby.

As a controlling-means for this resistance a relay is included in the circuit, the armature of which operates upon a break of the circuit to close said shunt circuit and thereby shunt the resistance out of circuit while said armature is retracted.

Upon a subsequent closure of the circuit, the armature in moving forward to its most attracted position will finally open .the

shunt circuit and thereby include the resistance again into the circuit after all the magnets in :the circuit have temporarily had the benefit of the increased currentto quickly and strongly energize them when most important -.to do so.

.lgo

.Theamount of resistance controlled by the relay may be varied, as desired for any particular circuit or condition desired, and the armature of said controlling-relay may be adjusted to move through a greater or less distance when retracted in response to a break in the circuit and be given more or less tension, as desired, and be arranged to open the shunt quite quickly on a closure of the circuit or to delay for an instant of more or less duration the opening of the shunt after the circuit closes and thus give time for all magnets to get fully charged, to en able them to respond properly to a signal under conditions of circuit which otherwise would have resulted in a failure for them to do so;

This invention is of especial value in noninterfering fire-alarm systems, in which the signal-circuits have signal-boxes arranged in series relation, each equipped with a non interference magnet as well as a bell-magnet, each of more orless resistance.

When several such boxes are caused to operate at the same time, which usually happens upon the occurrence of a very large and dangerous fire, the extra resistance which is then introduced by these magnets in the circuit substantially reduces the current just the time a strong current is most needed to operate the responding instruments, and the resistance cut-off by this invention can offset the cflfect of the resistance thus introduced.

Furthermore, by this invention, the speed of correct signaling may be materially increased for, upon the closures of the circuit a strong energizing current is insured at the moment of greatest need to energize the magnets of responding instruments to cause them to respond very quickly upon the C10- sures of the circuit, which time is the time of slowest response by an armature when a weak current only is available. In addition to this the immediate introduction of a noninductive resistance into the circuit after the responding magnets have become properly energized, promptly reduces the current and gives of itself no inductive or retardingeffect either at the close or break of the circuit,

and therefore when the circuit is again broken said magnets will. quickly discharge, due to the low current, and hence their armatures also will respond promptly to the breaks in the circuit.

This invention furthermore increases the reliability of the system from the fact thatas more current is available, to operate the responding magnets on the closures of the circuit a greater margin of safety for cor rect working of the signal responding means is insured. This is of great advantage, especially in fire-alarm systems, for 111 such systems the signal responding means are adjustedto one-standard and then left at such adjustment sometimes for a long period of time thereafter, without attention, and these signal-responding means are oftentimes lo cated in bell-towers and other more or less inaccessible places where they cannot be manually readjusted continually to accommcdate the varying conditions of the circuit as is done with the receiving instruments in commercial telegraphy where operators are constantly at the receiving instruments.

'lhisxinvention is also valuable in balancing signal-circuits having ground connections of well-known form, whereby the signal-responding means are caused to operate even though the signal transmitting-devices are operated while the signal-circuit is accidentally broken.

Such signals are generally sent by the use of normally open ground connections at the signal-sending stations and a permanentv ground, which is usually connected at the middle of the battery. \Vith such arrange ment but one-half of the battery would be available for signals sent through the ground connections while the metallic circuit was in a broken condition, and conditions could and do continually exist, where more than one half of the resistance of the line would be included in circuit when a signal-station was operated on a broken circuit and therefore the current available would be reduced to a point much below proper working condition.

\Vhen this relay and the resistance controlled thereby are connected in circuit at each side of the battery, then the resistance out out by the relay from either side would so improve conditions, automatically, as to afford good working conditions for either side of the circuit, to operate responding instruments of which there would be at leastone for each side.

Instead of grounding the battery in the middle it may be grounded at both poles, each through a resistance equal to perhaps one-half the resistance of the signal-circuit, thus forming two circuits from the battery of practically the same resistance and several signal-circuits could be connected to this same grounded battery.

In such case the signal responding means and the aforesaid relay controlled resistance would be connected in each side of the circuit, and when a signal was sent from a signalstation while the circuit was broken the entire current from the battery would pass through the grounded resistance at that side of the battery away from the operating signal-mechanism, and would be divided be tween the ground resistance and the then signaling-branch at the signaling side of the battery.

As a current divides inversely according to the resistance, by cutting out resistance in the signaling-branch, bythis invention most of the current could be diverted through such branch and insure correct working of the responding instruments in response to a signal which is being sent while the metal lic circuit remained broken.

Figure 1 is a diagram of an electric signalsystem embodying this invention, a signaltransmitting device of the absolute non-interference successive type being shown having a ground connection.

Fig. 2 is a diagram of an electric signalsystem embodying this invention, an ordinary form of signal-transmitting device of the absolute non-interference successive type being shown, without ground connection.

. Fig. 3 is a detail of a modified form of ground connection at the battery station.

Referring to Fig. l, a signal transmittingdevice of well-known form is shown wherein 10 represents the usual main toothed wheel of its signaling-train; 12 the lockinglever arranged to be held in a notch in en gagement with said wheel by a suitable spring, not shown, to hold the train at rest; 13 the pull by means of which the lockinglever is raised to release the signaling-t ain; 14 the signal-wheel; 15 the signaling-key arranged for cooperation with said signalwheel and also with the contact-members 16 and 17, to break and close the signal-circuit to transmit a signal; 18 the non-interference magnet; 19 a pivoted lever bearing the armature thereof which is arranged for cooperation with the signal-key 15, and with the-locking-lever 12, as usual in absolute non-interference successive fire-alarm boxes; 20 the bell-magnet; 21 a shunt-switch which is controlled by the locking-lever to include the non-interference magnet and bell-magnet in the signaling-circuit, when-the lockinglever is raised to release the signaling-train; 22 the pivoted contact-member which is connected with a ground branch-circuit 23, thereby to close or render operative said ground branch-circuit while the signalingmechanism is being operated.

This form of signal-transmitting means is shown merely for the sake of illustration, as, so far as my present invention is concerned the construction or type of signal-transmitting-means is not material, although advantages are obtained by its use in connection with signal transmittinganeans of the type here shown The signaling-key is normally held with the contact-members 16, 17, in closed position, so that the signal-circuit is normally closed; and 25 represents a signal-circuit which usually contains several other signaltransmitting-means, all arranged in series relation therein, and which extends to or includes a battery-station 26, and one or more signal-responding means.

At the battery-station normally closed ground branch connections 2T, 28, lead from each side or pole of the battery, through resistances, each representing say one-half of the resistance of the signaling-circuit.

In Fig. 3, a modification is shown wherein a single ground branclrcircuit 29 leads from the middle of the battery without including a resistance, yet both forms of ground connections are well-known;

In Fig. 1, the signal-responding means are arranged in the signal-circuit, at each side of the battery, respectively, 80 and 50,, representing signal-recorders, and 31 and 51, bells, and other instruments for receiving and translating or announcing signals may be employed, all 01"" which come within the general .term signal-responding means.

Fig. 2 shows another construction of circuit but which does not have the ground connections. In said figure is. illustrated a signal-recorder and a local battery 61 connected in a local circuit operated by a relay 62, which is connected in the signaling-circuit 25, which is a common practice. In this circuit, which is not grounded, the responding-means are distributed promiscuously without regard as to whether they are on one or the other side of the battery. All of said signal-responding means are arranged for operation by magnets controlled by or included in the circuits which are responsive to the breaks and closures of the circuit produced by the signal-transmitting means.

These systems, sorfar described, are of usual construction and are all open to the serious objections above noted. In overcoming such objections in accordance with this invention a resistance or resistances 35, 55, preferably of the variable non-inductive type, are or may be normally included in the circuit. one at each side of the battery where ground branches are used, and at any desired place where ground branches are not used, and means are provided to reduce or nullify said resistances.

As here shown, 86, 56, representcontrolling-relays which are associated with the resistances and which are included in the circuit at-each side of the battery, their armatures 37, 57, being responsive to the breaks and closures of the circuit produced by the signal-transmitting means, and said armatures are arranged to control shunt-circuits 38, 58, which are arranged around the resistances 35, 55, respectively.

These shunt-circuits are normally open, hence the resistances 35, 55,.are normally included in the signalingcircuit, but when the armatures of the controlling-relays are retracted said shunt-circuits are closed, thereby shunting the resistances out of the said signaling-circuit.

These shunt-controlling relays arerpreferably arranged to open the shunts only when their armatures are nearest the poles of the magnet, so that all magnets in the circuit will get the benefit of thestrong current during most of the time the relay-armatures are moving from their retracted positions.

These relay-armatures are preferably provided with adjustable front and back steps so that they may be set readily to move through any desired field, and are also provided with adjustable tension-springs that they may be adjusted readily as desired to meet diflerent requirements of circuits and they can be adjusted to retract when the strength of the current falls below a certain limit.

The magnet-coils themselves also may be wound with a comparatively small number of turns so that the magnets will lag in charging in comparison with other magnets in the circuit when it is desired to prolong the heavy current, and these relays may be modified in many other well known ways to meet local conditions as desired;

In Fig. 1, I have shown the shunt-coir trolling relav 36 with its armature 37, so arranged that when attracted, a projection 42 c rried b it will lift a shunt contactspring 89 away from the shunt contactscrew 40 and thus open the shunt-circuit 38, which is connected to such contacts, just before the armature arrives in its most attracted position.

7 An adjustable back-stop 41 and front stop 41', are provided for this armature so that it can be allowed more or less motion through any field as desired, and a tensionspring 43 and adj isting-means 44 for same is also provided to give various degrees of rectractile tension to the armature.

A slight modification of parts .for the 'accomplishment of the same end are also illustrated in connection with the relay 56, in which modification the shunt contactrspring 59 is carried by, but insulated from, the armature structure '57, which carries the shunt-contact 80. When this armature is attracted the outer end of the contact-spring 59, strikes an abutment-screw 82. mounted in the frame but insulated from the armature so that the' shunt-contacts will be held open when the armature is in its most attracted position.

In Fig. '2 a simple form of relay 76 is illustated, which also may be successfully usedto operate the shunt-circuit. It does not, however, have the same flexibility and range of adjustment for many conditions of service as 10 other forms.

I here are many modifications informs of relays that may be used with good results according to the ends desired, and the amountof resistance to be shunted will also vary according to the service demanded, and in signaling, where speed (of operation is iclesired,.t;he resistance used would prefer ably he of the non-indu tive type .so

there will be a quick discharge of the circuit when broken.

In c1rcu1ts where it 1s desired to have 7 but a very feeble current flowing normally;

on the line to save maintenance cost and to have a strong current when the clrcuit closes to insure speed of operation then the resist ance would be comparatively very high and the battery will be of the capacity necessary to give thedesired current when the resistance is shunted out of circuit. In practice this resistance would preferably be adjustable to readily meet varying conditions or requirements of service as found in the various places where they would be installed.

Increase ofspeed of fire-signaling is constantly demanded and, the only limit is the requirement of absolute reliability of the service. It is not enough that the signals shall be received correctly at a central station, but they must be received and announced correctly at the various houses of the department where the men are stationed in readiness to respond to an alarm, and oftentimes they must be repeated automati cally to such circuits or retransmitted manually by a key in such circuit or by a manually-set transmitter which can be adjusted to send any signal received at the central-station.

The circuits that connect these de :artmcut houses are sometimes termed alarmir cuits to distinguish them. as the alarmapparatus, such as bells, indicators, recorders, etc., have their controlling-magnets con nected in such circuits. Such magnets give a high inductive resistance to such cir uits. In order to have the signal-responding means insuch circuits work quickly, a very heavy current is often used, but the waste of current would be correspondingly great most of the time, as for instance. when no signal is being received. These circuits are often kept normally. open, thus sacrificing the constant test so valuable to announce instantly when a circuit breaks. and therefore such circuits may become accidentally broken and the fact nct known until a signal has been lost which was attempted to be sent over such circuit during an undiscovered brealc This invention, when introduced into such a circuit. is of especial value for the resistance which it introduces could be so high that it could keep the circuit closed nor mally, to keen it under continual test with but a small flow of current and still have the strong current applied automatically when needed.

IVhcn such circuit ,is broken the armatures of the controlling magnets would then respond .more quickly than before, as there would vbe less induction at such time due to the low current flowing while the circuit was closed, and the magnets would also 'lllli charge on a closure as quickly as before, as

the conditions at such time are not changed.

This invention therefore increases the efficiency and speed at which signals may be sent and received over all circuits containing signal-transmitting means, and its use will increase the reliability, efficiency and speed at which signals may be properly repeated and announced over circuits for alarm purposes, and it will also increase the efficiency of such alarm-circuits even though they are normally open, as the cutting down of the current the instant it has done its important work will enable a quick discharge of the magnets and consequently a corresponding quick response of their armatures.

I claim 1. In an electric signal-system, the combination with an electric circuit, signals transmitting means arranged to repeatedly open and close said circuit to transmit a signal, signal-responding means including a' magnet arranged-in said circuit which is responsive to the breaks in said circuit to cause said means to respond, and to the closures in said circuit to restore the signal-responding means, of current-varying means normally included in the circuit, and a single means controlled by the circuit and arranged for operation upon each break to set the current-varying means in condition to increase the strength of the current, and upon each closure to restore the current-varying means to normal after a short period of time, during which time a strong energizing current is caused to flow, to energize the magnet of the signal-responding means and restore said means.

2. In an electric signal-system, the combination with an electric circuit, signal-transmitting means arranged to repeatedly open and close said circuit to transmit a signal, and signal-responding means including a magnet arranged in said circuit and responsive to the breaks and closures thereof, of a current-varying element normally included in said circuit, and a relay controlling said current-varying element which is responsive to the successive breaks and do I sures of the circuit during the transmission of the signal, whereby upon each break a strongcr'current is available which is caused to flow upon each subsequent closure for a short period of time, to energize the magnet of the signal-responding means.

'3. In an electric signal-system, the combination with an electric circuit, signal-transmitting means arranged to'repeatedly open and close said circuit to transmit a signal, and signal-responding means including a magnet'arranged in said circuit and responsive to the breaks and closures thereof, of current-varying means normally included in said circuit, and a relay controlling said current-varying means which is responsive to the transmission of the signal, whereby upon l each break'a stronger current is available which is caused to flow for a short period of time upon each closure toener'gize the magnet of a signal-responding means, said relay being arranged'to act more slowly than the magnet of the signal-responding means.

4. In an electric signal-system, the combination with an electric circuit, signal-transmitting means arranged to repeatedly open and close said circuit to transmit a signal, and signal-responding means including a magnet arranged in said circuit and responsive to the breaks and closures thereof, of a current-varyingelement normally included in said circuit, and a relay controlling said current-varying element which is responsive to the successive breaks and closures of the circuit during the transmisison'of a signal, the contact-members of said relay being open when the armature is in attracted position, and when said armature is'retracte'd, upon a break in the circuit, said members will be closed and the current-varying element will be arranged in the circuit to increase the strength of the current, and when attracted, upon a closure in the circuit, said currentvarying meanswill be restored to normal, and during its attractive movement, while the circuit is closed, a strong energizing current will flow to energize the magnet of the signal-responding means. g r p 5. In an electric signal system, the combination with an electric circuit, signal-t ansmitting means arranged to repeatedly open and close said circuit to transmit a signal, and signal-responding means including a magnet arranged in said circuit, which is responsive to the breaks and closures thereof during the transmission of a signal, of a single means controlled by the circuit and arranged for operation upon each break thereof to reduce the resistance in the circuit, and upon each subsequent closure to increase the resistance after a short period of time, so that a stronger current is available during such short period of time to energize the magnet ofthe signal-responding means.

6. In an electric signal-system, the combination with an electric circuit, signaltransmitting means arranged to repeatedly open and close said circuit to transmit a signal, and signal-responding means including a magnet arranged in said circuit and responsive to the breaks and closures thereof, of a resistance element normally included in said circuit, and a relay controlling said resistance element, which is-responsive to successive breaks and closures in the circuit during the transmission of a signal to nullify said resistance upon the breaks, a'ndto restore theresistanceiupon; the closures after a -short=period Oftinie,

during which time a strong energizing current is available to energize the magnet of the signal-responding means.

7. In an electric signal-system, the combination with an electric circuit, signal-transmitting means arranged to repeatedly open and close said circuit to transmit a signal, and signal-responding means including a. magnet arranged in the circuit and responsive to the breaks and closures thereof, of a resistance element included in the circuit, a shunt for said resistance element, and a re lay controlling said shunt which is responsive to each break and closure of said circuit during the transmission of a signal, whereby the shunt is closed and the resistance is reduced upon the breaks and a strong energizing current is available temporarily to energize the magnet of the signal-responding means upon the closures, until the shunt is opened by the relay.

' 8. In an electric signal-system, the combination with an electric circuit, signal-transmitting means arranged to repeatedly open and close said circuit to transmit a signal, and signal-responding means including a magnet arranged in the circuit and responsive to the breaks and closures thereof, of a resistance element included in the circuit, a shunt for said resistance element, and a relay controlling said shunt which is responsive to the successive breaks and closures in a circuit during the transmission of a signal, the contact-members of said relay being open when the armature is in attracted position, and when said armature is retracted upon a break in the circuit, the shunt will be closed, and when attracted, upon a closure in the circuit, the shunt will be opened, and during its attractive movement, while the circuit is closed and the shunt also closed, a strong energizing current will flow to energize the magnet of the signal-responding means.

9. In an electric signal system, the combination in a normally closed electric circuit, of signaltransmitting means arranged to re peatedly open and close said circuit to formulate a signal, responding means in said circuit arranged to indicate or announce the signal transmitted, a high resistance normally included in said circuit, a normally open shunt of low resistance for said high resistance, a switch for closing and opening the low resistance shunt connections around the high resistance, an electro-magnet with its coils permanently connected in series in the circuit and with the signaltransmitting means and source of energy, so as to be always responsive thereto, an armature in the magnetic field of said magnet adapted to operate and wholly control said switch and to close same on failure of current in said circuit and the consequent retraction of said armature therefrom, to thereby shunt the high resistance from the circuit, to prevent it from reducing the current, said armature opening said switch after closure of the circuit to thereby break the shunt of low resistance so as to include the high resistance in series in the circuit and thereby decrease the flow of current by attraction of the armature by its magnet upon closure of the circuit and thereafter during the time said circuit remains closed in proper working condition.

10. In an electric signal-system, the com bination with a closed electric-circuit having a ground-connection at the battery-station, means in said circuit having normally open signal-transmitting ground-connections and arranged to open and close said closed circuit and also said ground-circuit connection to the circuit simultaneously when operated to transmit a signal, and signal-responding means including a magnet arranged in said circuit at each side of the battery and responsive to the breaks and closures thereof, and means arranged in the circuit at each side of the battery and controlled by the circuit and operating upon a break thereof to increase the strength of the current, whereby a stronger current is available temporarily, upon a subsequent closure of the circuit to energize the magnets of the signal-responding means, substantially as described.

11. In an electric signal-system, the combination with a closed electric-circuit having a ground-connection at the battery-station, a signal-transmitting means in said circuit with normally open ground-connections and arranged to open and close said closed circuit and also said ground connection simultaneously to transmit a signal, and signalresponding means including a magnet in said circuit at each side of the battery and responsive to the breaks and closures thereof, and means arranged in the circuit at each side of the battery and controlled by the circuit and operating upon a break thereof to FREDERICK W. COLE.

Witnesses:

B. J. Noyes, H. B. DAVIS.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. W

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