US763970A - Party-line telephone system. - Google Patents

Description

N0. 763,970. PATENTED JULY 5, 1904.

T. C. DRAKE. PARTY LINE TELEPHONE SYSTEM.

APPLICATION FILED FEB.13,1903.

N0 MODEL. 2 SHEETS-SHEET l- W as [if flllllf iiF I] it.

T a b WTITESEEE; a I T No. 763,970. PATENTED- JULY 5, 1904 T. 0. DRAKE.

PARTY LINE TELEPHONE SYSTEM.

APPLICATION FILED FEB. 13. 1903.

N0 MODEL. 2 SHEETS-SHEET 2.

Patented July 5, 1-904.

PATENT OEEIQE.

THOMAS C. DRAKE, OF MALTA, OHIO.

PARTY-LINE TELEPHONE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 763,970, dated July 5, 1904,

Application filed February 13, 1903. Serial No. 143,163. (No model.)

To all whom it may IZOILCIJ'II/J Be it known that 1, THOMAS C. DRAKE, a citizen of the United States, residing at Malta, in the county of Morgan and State of Ohio, have invented certain new and useful Improvements in Party-Line Telephone Systems, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to party-line telephone systems with selective or non interfering bells.

The object of my invention is to provide an improved method of selective ringing biased polarized call-bells in party-line telephone systems.

In the prior art it has been proposed to connect two oppositely biased polarized bells on either side of a metallic circuit and ring over the different circuits formed by using the separate limbs of the line with the ground as a common return. The bells or ringers have been biased by means of a light spring acting upon the pivoted armature to retain the armature normally in a position toward which it would be attracted by a current in a direction not intended to operate the bell.

With two ringers thus oppositely biased and connected from one limb of the line to ground in their operative condition a pulsating plus or minus current has been sent over the limb of the line to selectively oper ate the ringer adapted to respond to the current sent out in a predetermined direction, the other ringer being unresponsive for the reason that the current operating one will assist the light spring in retaining the bias of the other. In systems of this character the biasing-spring of the ringer has been depended upon entirely for the return or retracting stroke of the polarized armature after change inresistance of the line, the bells require an adjustment to conform to the varying condition in order to operate perfectly.

One object of my invention is to obviate this deficiency and make it possible to operate a biased bell under greatly varyingconditions as regards speed or frequency of the ringingmachine and the resistance of the line-circuit.

My invention contemplates giving the polarized armature of the ringer a certain amount of bias, either by gravity or by a spring, magnet, or other means; but I do not depend upon the bias entirely for the return or retracting movement or stroke of the armature after having been actuated in opposition or against the biasing force by a pulsation or alternation of the required strength and polarity.

My invention contemplates employing an alternation or half-wave of a definite strength and polarity to assist the biasing force in actuating the polarized armature in the direction of its normal bias or trend. In practice 1 prefer to arrange suitable ringing apparatus in such a manner as to obtain an alternation for assisting the bells biasing force in the retracting stroke of the armature of about onethird the electromotive force of the alternations employed to actuate the armature in opposition to the biasing force.

In the specification and claims I will refer to the alternations or half-waves which are intended to actuate the polarized armature against the biasing force as the heavy or major alternations or half-waves and to the alternations or half-Waves which are intended to assist the biasing force in the retracting stroke of the armature as the light or minor alternations or half-waves.

By means of my present invention 1 am enabled to operate polarized bells entirely satisfactory by mounting the same in such amanner that the weight of the tapperwire and ball only are depended upon for the biasing force of the armature, and as the usual spring is obviated the ringer is much more sensitive, and Will therefore operate through greater resistance. In practice I prefer to mount the bell so that the same is biased by the weight of its own moving element; but I do not limit operate at the present time.

my invention to bells mounted in this manner, as any polarized bell properly biased with a spring or other means will operate satisfactory.

Another object of my invention is to obviate the trouble incident to operating biased bells with pulsating current over long lines and underground cables, as the static capacity of such lines tends to convert the pulsating current into alternating current of such character as will give an annoying operation or chatter of the bell intended to remain silent. ly operating the bells with an alternating current in the manner hereinafter set forth inductance and static capacity as encountered in practice will not interfere in any way with the selective operation of the bells.

An important feature of my invention relates to the amount of resistance practical to place in each bell-circuit.

According to my invention the ringers or the circuits including the ringers may be as high as iifty thousand ohms; but the resistance is preferably less, for the reason that fifteen thousand to twenty thousand ohms has been found to be suiiieient for all conditions under which the system may be required to This is accomplished by reason of obviating the usual type of biased ringer, in which the pulsating current is counteracted by a spring. This comparatively high resistance gives to my system several important features which are not present in similar systems in use before my invention--namely, the constant loss of current through the ringers when working the system on common-battery circuits is reduced to a minimum, the margin in line resistance between the talking and signaling condition of the system is suflicient for properly operating the line-relays in common-battery systems, and the kick from cord-circuit and cutoif relays, as well as the discharge from condensers sometimes used in the cord-circuit, will not affect the }')arty-line bells by giving an impulse or tap on all of the bells when inserting or withdrawing a plug from the line connection terminal or jack.

In so far as connecting the ringers with the line-circuit is concerned my invention doesnot contemplate a method different from systems in common use at the present time; but instead of employing the usual plus and minus pulsating current to selectively operate the bells I employ an alternating current, as before stated.

In practice I employ an alternating current with about ninety volts in one alternation or half-cycle and about thirty volts in the alternation or half-cycle of opposite sign. I prefer to produce the desired alternating current by connecting a source of steady current, such as a battery, with an alternating current such as is generated by the usual type of ap paratus for ringing telephone bells. The source of steady current is employed to suitably counteract the positive alternation and correspondingly augment the negative alternation to ring a bell biased in one direction and to suitably counteract the negative alternation and correspondingly augment the positive alternation to ring a bell biased in the opposite direction.

In practice the alternatingcurrent generator is designed to give about sixty volts and the steady-current generator about thirty volts, the two generators being preferably connected in series whereby to produce an alternating current with one alternation or halfwave augmented to ninety volts, herein referred to as the major or heavy alternation, and the alternation or half-wave of opposite sign counteracted to about thirty volts,

herein referred to as the minor or light alternation 0r half-wave.

The desired alternating current may be taken from a steady-current batteryand a suitable pole-changer, the apparatus being arranged to give about ninety volts of positive polarity and thirty volts of negative polarity to operate one of the bells and about ninety volts of negative polarity and about thirty volts of positive polarity to operate the op positely-lt iased bell.

Referring to the accompanying drawings, Figure l is a diagrammatic view of a fourparty telephone system operated according to my invention. Fig. 2 is an extraction of Fig. l, which will serve as a theory diagram. Fig. 3 represents my invention employing two distinct sources of alternating current, and Fig. at is the iireferred type of polarized bell biased by the weight of its moving element.

Like characters refer to like parts throughout the several figures.

Referring to Fig. 'l, the limbs (I 1/ of the party-telephone line extends to the four substations, and the transmitters and receivers c are connected between the metallic-circuit limbs o a, the receivers being adapted when on the switch-hooks to open the circuit, and thus cut the telephone apparatus out of circuit in the usual manner in the unused condition of the system.

At substations A and B are providml biased polarized bells (l M, respectively, the bells being biased in opposition to one another and connected in multiple with limb a and the ground as a return-circuit. One of the bells, (I, is biased, so that a positive major alternation or half-wave will actuate the polar izcd armature in opposition to the biasing force, and a negativeminoralternation or halfwave will assist the biasing force in the return stroke of the ari'nature, and the other bell, r1, is biased oppositely, so that a negative major alternation will actuate the polarized armature in opposition or against the bias ing force and a positive minor alternation will assist or augment the biasing force in the return stroke of the armature.

At substations Candi) are provided biased bells c w, the bells being connected between limb a and the ground in the same manner as the bells on the other side of the metallic circuit. Bell a is biased, so that a negative major alternation will actuate the polarized armature against the biasing force and a positive minor alternation will assist the biasing force in the return stroke of the armature, while the other bell, a, is oppositely biased and re quires a positive major alternation to counteract the bias and a negative minor alternation to assist the biasing force in operating the bell to signal.

The limbs a u/ of the telephone-line terminate in the usual spring-jack 7" at the central station, which according to this diagram comprises line-springs j" with which the terminals of the plug g are adapted to make .contact when the plug is inserted into the spring-jack. The tip-contact /of the plug is adapted to register with the short linespring f, while the sleeve-contact is adapted to register with the long line-spring f As this circuit is traced the two line-springs f" normally rest against contact-anvils f f, respectively, the contact-anvils being connected directly with a common battery and an individual line-relayf. hen any one of the receivers are removed from the switch-hook, the common battery energizes the individual line-signal to apprise the central operator that her assistance is required. When the receivers are restored to the switches, the line-signal is inactive, for the reason that the high resistance of the ringers, bridged with both sides of the line to ground, allow but a very slight current to escape throughthe line-signal.

The operators listening-in key has been omitted from the drawings for clearness; but it may be of any suitable arrangement as employed in the art.

The operators cord is provided with four selective ringing-keys of the usual construction, which for ready identification are preferablynumbered 1, 2, 3, and 4. The keys are provided with contact-springs l: Zm and /t Z Z m, respectively, normally resting against contacts which are adapted to maintain the cord-circuit continuous to a mateplug, which plug is adapted for insertion into another line for conversational purposes. This plug is not shown in the drawings. All of the contact-springs have suitable back contacts, by means of which the various comvbinations of positive and negative steady current and alternating ringing-current may be connected with the proper limb of the metallic circuit for selecting the desired bell.

Referring to Fig. L,.the arrangement and construction of the ringer or call-bell may be understood. This is the apparatus by means I gon gs.

of which an audible signal is produced at the various substations. The general construction of this ringer is that of the commercial forms now universally adopted in telephonework and depends for its mode of action upon the same principles. In front of the electromagnets, the coils w w of which are connected in series, is pivoted in a yoke 10 an armature 20 This armature is given a permanent magnetization by means of a permanent magnet on in the usual manner. The bell-hammer wire 10" is securely attached to the middle of the armature and carries at its outer end the usual ball for striking the In'order to give this ringe'r movement a gravitational set or tendency toward one side only, I mount the ringer with its greater dimension vertically instead of horizontally, the latter being the common practice. 1 am aware that this is not good practice if the ringers were to be actuated by means of plus and minus pulsating direct current according to the prior art; but with my system it is perfectly practicable and desirable to mount the ringer movement in this manner.

One of the preferred methods of producing the required major and minor potential alternations for ringing the call-bells is provided by connecting a source of steady current, such as a battery, in series with the altertern ating-current generator of suitable design for ringing the bells, and this present Letters Patent will set forth the invention with the bell-ringing generators so connected; but I do not limit my invention to generators connected in any particular manner for producing the major and minor alternations and have inserted claims generic in scope, while in other Letters Patents I will disclose and specifically claim certain modifications of the invention which relate to methods of producing the required major and minor alternations for selectively ringing the bells.

Referring to Fig. 2, the invention is represented diagramatically as one wire or one limb of the metallic circuit with two bells biased in opposition to one another and connected in multiple to ground. The limb or line circuit 0 extends from the selective-keys p and p to the two substation-bells r) and 0 Key 7 is adapted to connect the positive steadycurrent source a with the line-wireo, and key 1) is adapted to connect the negative steadycurrent source a with the line-wire 0. The

negative terminal of the steady source a) and positive terminal of steady-current source 01/ are connected together and grounded through the alternating-current generator r, the function of the three generators being to produce an alternating current with the positive alternation or half-wave of greater potential than the negative alternation or half-wave to ring one bell and the negative alternation or halfwave of greater potential than the positive &

alternation or halt-wave to ring the oppositelybiased bell.

\Vhen it is desired to ring positively-liiased bell u and have the negatively-biased bell remain silent, the key 7) is pressed. This operation connects the positive steady current source 01 in series with the alternating-current generator -r to ground and through the two bells 1/ and n in multiple to ground. (Dallbell r) is biased to ring when the steady cur rent from battery or partially counteracts the alternations or haltwaves, which are or opposite polarity to the steady current, thereby producing the heavy and light or major and minor alternations of the required polarity to. operate call-bell 11.

When it is desired to ring the negativelybiased bell I) and have the positively-biased bell 0 remain silent, key 2 is pressed. This operation connects the negative steady-current source w in series with the alternatingcurrent generator 9' to ground and through the two bells in n'iultipleto ground. (all-bell 0 is biased to ring when the steady current from battery 1/ partially counteracts the alternations or half-waves, which are oi opposite polarity to the steady current, thereby producing the heavy and light or major and minor alternations or half-waves necessary to ring bell ln this case the counteracted alternations or halt-waves are of opposite polarity from those which were counteracted when ringing call n.

it is obvious that either call-bell may be solectively rung and the oppositely-biased callbell silenced by simply reversing the polarity of the steady current operating in conjunction with the usual bell-ringing or alternating current. .I do not limit myself to two sources of stead y current adapted to be connected with the alternating generator, as means may be provided for reversing the polarity of a sin-' gle source of source of steady current connected therewith, nor do I limit myself to a single source of alternating current, as is diagrammed in Fig. 2, as two alternating-current generators and two sources of oppositepolarity steady current may be employed, each alternating-current generator being connected with a particular polarity of steady current for operating one particular bell, as is diagrammcd in Fig. 3, where 15 is a positive steady battery connected with an alternating current generator 1/ and adapted to select ively ring biased bell s when key is pressed,

and t is a negative steady battery-connected with another alternating-current generator 1/ and adapted to selectively ring biased bell s to the exclusion of bell a when key 1/ is pressed in the act of connecting ringing-current to line s.

Referring to Fi 1, the circuits will be traced for operating the four dilierent substations. There is an alternating-current generator a", tapped to the center of a battery/if at the point 7 Of course this battery may be any suitable source of direct current with the proper clectromotive force. hen it is desired to ring the bell at substation A, the key 1 is pressed, thus closing circuit through generator 1r, battery i, contact a, spring 7:, cord-strand a, tip 1 of plug 1 short linespringf", limb u, and through the two bells and (1 in multiple to ground. The current from battery I being positive to line and bells and negative to alternator will partially counteract the negative alternations and correspondingly augment the positive alternations, thereby producing the required major and minor alteri'iations for selectively operat ing the biased bell at substation A, the major alternations actuating the biased armature in opposition to the biasing force and the minor alternations assisting the biasing force in the return or retracting strokes of the armature.

\Vhen it is desired to ring the bell at substation B, the key 2 is depressed, thus closing circuit through generator in, battery 7, con tact F", spring Z, cord-strand e, tip of plug y, short line-spring f, limb a, and through the two bells and d in multiple to ground. The current from battery is of a .reverse character from that which was connected with limb (I, when key 1 was depressed, being new negative. The negative polarity steady cur rent will suitably counteract the positive altcrnations of alternator ,1: and correspondingly augment the l'lGgtillVG alternations for selectively operating the biased bell at substation E.

W hen it is desired to ring the bell at subvTOO station (l, the key 3 is depressed, which closes a negative steady current and the alternating current in series through generator :1 battery j, contact l, spring i, cord-strand sleeve of plug long line-spring f, linib u, oi the metallic circuit, and through the two bells (1 and w in multiple. The steady current being of negative polarity will suitably counteract the positive alternations or halfwaves of the alternating current from generator :1? and. will correspondingly augment the negative alternations or halt-waves from the same generator, whereby the positive alternations or half-waves will not have strength enough to actuate biased bell 1/ at substation I), while the augmented alternation or halfwaves will have sufficient strength to actuate the call-bell at substation (1, which is biased to respond to a major negative alternation or half-wave and a minor positive alternation or half-wave.

When it is desired to ring the bell at substation l), the key 4 is LlClH'GSSGtl, which closes a positive steady current and the alternating current in series through generator ir, bat tery 7', contact 0/1,, spring m, cord-strand 0, sleeve of plug g, long line-springf, limb m, and. through the two bells a and (2' in multiple. Under this condition of the system the positive steady current in series with the alternator 1r will suitably counteract the negative alternations or half-wave of the alternatingeurrent and correspondingly augment the positive alternations or halt'waves ot' the al ternating current, whereby the negative alternations or half-waves will not have strength enough to actuate call-bell e at substation C, while the augmented alternations or halfwaves will have suificient strength to actuate the call-bell c at substation D, which is biased to respond to major positive alternations or half-waves and minor negative alternations or half-waves. In circuits of this character some means must be provided to prevent the accidental ringing of the two like bells on the opposite sides of the metallic circuit when any party has a receiver off the switch. It is obvious from the diagram that it is proposed to ground that limb of the line not being rung over. 'For instance, on depressing key Z to connect the spring A with the positive battery v' and generator a: the opposite spring A is connected to ground, thus grounding limb (/',and should a telephone-receiver be removed from the switch-hook and a path of low resistance thus provided to the grounded limb the direct and alternating current will be shunted and suiiicient current will therefore not pass through the bells to ring them. i

In Fig. 1 l have showna connection-plug equipped with four party-line keys. Instead of providing this number of keys for each cord-circuit of the switchboard, a single set of keys may be provided and adapted to be connected with any particular set of cord eonductors that may be for the time in use.

Throughout this specification I have shown and described my system with ground-returns and for metallic circuits; but this is by no means the limitation of the system, it being readily applicable to common return systems and telephone systems of almost any character. I have also shown and described my invention in connection with a specific line-circuit in which the bells are permanently connected therewith; but it is obvious that my invention is applicable to operating biased-bell partyline systems in which the bells are normally disconnected from the line, but adapted to be connected therewith in their operative condition by suitable means, such as relays. My system is also readily adapted to magneto call systems and switehboards.

Having .described my invention. what I claim as new, and desire to secure by Letters Patent, is-

1. In a party-line system the combination with a line-circuit of two opymsitely-biased call-bells connected with the line in their operative condition, an alternating current connected with the line to selectively ring the bells, the alternating current having the positive alternation or half-wave of suitable strength to operate one of the bells armatures against the biasing force exerted on said armature, and the negative alternation or half-wave of suitable strength to assist the biasing force in the return stroke of the bells armature but not of sufficient strength to operate the oppositelybiased bells armature, and means to reverse the polarity of the major and minor alternations or halt-waves in the act of selectively ringing the other biased bell, substantially as described.

2. In a party-line system, the combination with a line-circuit of two oppositely-biased call-bells connected therewith in their operative condition, an alternating current to selectively operate the bells, the alternating current having one alternation of greater potential than the alternation or half-wave of opposite sign, the alternating current having the positive alternation or half-wave greater to ring one hell, and the negative alternation or half-wave greater to ring the oppositely-biased bell, the major alternations serving to actuate the bells armatures against the biasing force thereof, and the minor alternations serving to assist the biasing force in operating the bells armatures toward their normal position, substantially as described.

3. In a party-line system the combination with a line, of two oppositely-biased call-bells connected with the line in their operative condition, and a major alternation or impulse of positive polarity to actuate the positivelybiased bell in opposition to the biasing force, and a major alternation or impulse of negative polarity to actuate the negatively-biased bell in opposition to the biasing force, and a minor alternation or impulse of negative polarity to assist the biasing force in retracting the armature ot' the positively-biased bell, and a minor alternation or impulse of positive polarity to assist the biasing force in retracting the armature of the negativelybiased bell, and means to connect a major positive alternation or impulse and a minor negative alternation or impulse with the line to selectively operate the positively-biased bell, and means to connect a major negative alternation or impulse and a minor positive alternation or impulse with the line to selectively operate the negatively-biased bell, substantially as described.

L. In a party-line system, the combination with a line-circuit of two biased polarized callbells connected therewith in opposition to one another, an alternating current connected with the line to selectively operate one of the bells to the exclusion of the other, the alternating current having one alternation of higher electromotive force than the alternation of opposite sign, whereby the bell intended to ring will have the biasing force of the armature counteracted by the major electromotive-force alternation, and the biasing force of the armature augmented by the minor electromotiveforce alternation in the act of oscillating the polarized armature by the alternating current to ring the selected bell, substantially as described.

5. In a party-line system, the combination with a line-circuit, of two call-bells having oppositelybiased polarized armatures, and means to connect a source of alternating current with the line to selectively ring one of the bells to the exclusion of the other, the alternating current having a major alternation to actuate one otthe bells against its biasing force, and a lninor alternation of opposite sign to assist the hell's biasing force in the return or retracting stroke of the armature, and means to connect a second alternating current with the line to ring the other bell, the second al ternating current having the major and minor alternations of reverse polarity from the major and minor alternations respectively, of the first alternating current, substantially as described.

6. The combination in a party-line system, of biased ringers connected. with the line-circuit, an alternating currentconnected with the line-circuit to selectively operate the ringers biased in one direction, and a source of steady curren t connected with the alternating current to suitably augment one alternation, and suitably counteract the opposite alternation, whereby the biased ringers intended to signal will be actuated against the biasing force by the augmented alternations and actuated toward or in the same direction as the biasing force by the coui'iteracted alternations in the act of operating the ringers to signal, substantially as described.

7. .In a selecti vesignal in g telephone system, the combination with a line, of two polarized call-bells connected with the line for signaling, an alternating current with the positive alternation of greater potential than the negative.

alternation to selectively operate one of the bells, and an alternating current with the negative alternation of greater potential than the positive alternation to selectively ring the other bell, and means to connect the proper current with the line to selectively ring the desired bell, and means to bias the bells oppositely to such a degree that the major alternations will actuate the ringing bell against the biasing force, and the minor alternations will assist the biasing force in operating the ringing bell toward the normally biased posi-' tion, substantially as described.

8. ]n a. party-line system, the combination with a line-circuit, of biased polarized callbells connected therewith for selective signal ing, an alternating current with one alternation of greater potential than the other, and means to connect the alternating current with the line for selectively ringing the bells biased in one direction, the bias of the bells being such as to require the major potential alternation to operate the polarized armature against the biasing force, and the minor potential alternation to assist the bells biasing force in operating the polarized armature toward the biased side in the act of ringing the bells, substantially as described.

9. In a party telephone system, the combination with two metallic limbs extending from the central station through four subscribers stations, of a telephone set at each of said subscribers stations connected in a normally open bridge extending between the two metallic limbs, whereby the telephone set at any one of the subscribers stations may be individually connected between the metallic limbs, a polarized call-bell at each of said subscribers stations, two of said call-bells being oppositely biased and connected. between one of said metallic limbs and the ground, the remaining two call-bells being oppositely biased and connected between the other metallic limb and ground, tour keys at the central station organized to connect a suitable altermtting current over the metallic limbs for selectively operating one of the tour call-bells, the alternating-cu rrent apparatus being organ ized to generate an alternating current with one alternation of suitable strength to counteract the biasing force of the biased polarized bells, and the alternation of opposite sign of suitable strength to assist the biasing torce of the biased polarized bells in operating the bell toward the normally biased side, the alternating-current apparatus comprising an alternating generator and a source of steady current connected with the alternating generator in a suitable manner to augment one alternation to suitable strength, and counteract the alternation of opposite sign to suitable strength, substantially as described.

10. .In a party-line system, the combination with two metallic limbs extending from the central station through four substations, of telephone sets at each of said substations connected in a normally open bridge extending between the two metallic limbs, whereby the telephone set at any one of the substations may be individually connected between the metallic limbs, a polarized call-bell at each of said. substations, two of said call-bells being oppositely biased and connected between one of said limbs and the ground in their operative condition, the remaining two *all-bells being oppositely biased and connected between the other limb and ground in their operative condition, the call-bells being organized to require a major alternation to actuate the biased moving element in opposition to the biasing force thereof, and a minor alternation to assist the biasing force in the retracting stroke of said biased moving element, four keys at the central station organized to connect suitable alternating current over the metallic limbs for selectively operating the tour bells, two of said keys being connected with positive steady current, the positive steady current being connected to ground through an alternating-current generator for producing the major and minor alternations required to operate the two similar-biased bells on either metallic limb, the two remaining keys being connected with negative steady current, the negative steady current being grounded through an alternating-current generator for producing the major and minor alternations required to operate the remaining two similar-biased bells on either metallic limb,substantially as described.

11. In a selective ringingtelephone system, the combination with a metallic circuit, of two oppositel biased call-bells connected from either side of the circuit to ground when signaling-current is sent over the circuit. the callbells being organized to ring with a heavy alternation or impulse of current which will actua-te the biased armatures ot' the bells in opposition to the biasing force exerted thereon, and a light alternation or impulse of current v which will augment or assist the biasing force in the operation of the biased armatures in the direction of their normal biased trend, an alternating current, and a source of positive steady current, and means to connect the alternating current and positive steady current in series and with either side of the metallic circuit for producing the required heavy and light alternations or impulses for operating the bells biased in one direction, and a source of negative steady current, and means to connect the alternating current and the negative steady current in series and with either side of the metallic circuit for producing the required heavy and light alternations o'r impulses for actuating the bells biased in the opposite direction, substantially as described.

12. In a party-line telephone system, the combination with a line-circuit of two oppositely-biased call-bells connected therewith in their signaling condition, the biased bells being organized to operate with a heavy alternation or impulse of current to actuate the biased armatures of the bells in opposition to the biasing force exerted thereon, and a light alternation or impulse or current of opposite polarity to assist the biasing force in the operation of the biased armatures in the direction of their normally biased trend, two keys organized to connect suitable current with the line-circuit for selectively operating the bells, a source of positive steady current, a source of negative steady current, and a source of alternating current, one of said keys being connected with the positive steady current, the positive steady current being connected in series with the alternating-current source for producing the heavy and light alternations or impulses req uired to operate one of the biased bells, the other key being connected with the negative steady current, the negative steady current being connected in series with the alternatingycurrentsource for producing the required heavy and light alternation or impulses for operating the oppositely-biased bell, substantially as described.

13. In a party-line telephone system, the combination with a lie e-circuit of two high-resistance biased polarized call-bells permanently bridged with the line-circuit, the biased bells being organized to operate with a heavy alternation or impulse of current to actuate the biased armature of the-bell in opposition to the biasing force exerted thereon, and a light alternation or impulse of current of opposite polarity to assist the biasing force in the operation of the biased armature in the direction of its normally biased trend, two keys organized to connect suitable current with the line-circuit for selectively operating the bells, a source of positive steady current, a source of negative steady current, and a source of alternating current, one 01 said keys being connected with the positive steady current, the positive steady current being connected in series with the alternating-current source for producing the heavy and light alternations or impulses required to operate one of the biased bells, the other key being connected with the negative steady current, the negative steady current being connected in series with the alternating-current source for producing the heavy and light alternations or impulses required to operate the oppositely-biased bell, substantially as described.

14. In a party-line telephone system, two polarized call-bells biased in opposition to one another and connected with a line-circuit, the bells being organized to operate with a heavy alternation of current to actuate the biased armatures of the bells in opposition to the biasing force exerted thereon, and a light alternation of current of opposite polarity to assist the biasing force in the operation of the biased armature in the direction of their normally biased trend, and means connected with the line-circuit for producing the required heavy and light alternations, the means consisting of an alternating-current generator and a source of steady current, the alternating-current generator and the source of steady current being connected in series whereby one alternation of the alternating current from said generator is suitably counteracted for producing the light alternation, and the other alternation of the alternating current from said generator is suitably augmented for producing the heavy alternation, and means to connect the source of steady current through the alternatingcurrent generator in one direction to selectively ring one of the biased bells, and means to reverse the polarity of the source of steady current through said alternating generator to ring the oppositelybiased bell, substantially as described.

15. In a party-line telephone system, two polarized call-bells biased in opposition to each other and connected. with a line-circuit for signaling, one of said bells being organized to operate with a heavy positive alternation of current to actuate its biased armature in opposition to the biasing force exerted thereon, and a light negative alternation of current to assist the biasing force in the operation of its armature in the direction of its normally biased trend, the other call-bell being organized to operate with a heavy negative alternation of current to actuate its biased armature in opposition to the biasing force exerted thereon, and a light positive alternation of current to assist the biasing force in the operation of its armature in the direction of its normal biased trend, a source of positive steady current connected in series with an alternating-cnrrent generator, and a source of negative steady current connected in series with an alternating-current generator, means to connect the alternating-current generator with the positive steady current in series, with the line-circuit to selectively ring the biased bell organized to operate with a heavy positive alternatioi'i, and means to connect the alternating-current generator with the negative steady current in series, with the linecircuit to selectively ring the biased bell organized to operate with a heavy negative alternation, substantially as described.

16. In a party-line telephone system,two polarized call-bells biased in opposition to each other and connected with a line-circuit for signaling, one of said bells being organized to operate with a heavy positive alternation of current to actuate its biased armature in opposition to the biasing force exerted thereon, and a light negative alternation of current to assist the biasing force in the operation of its armature in the direction of its normally biased trend, the other call-bell being organized to operate with a heavy negative alternation of current to actuate its biased armature in opposition to the biasing force exerted thereon, and a light positive alternation of current to assist the biasing force in the operation of its armature in the direction of its normally biased trend, an alternating-current generator, and a source of positive steady current connected in series therewith for producing the heavy positive alternation and light negative alternation for operating one bell, and means to reverse the polarity of the steady current for producing the heavy negative altel-nation and light positive alternation for operating the other bell, substantially as described.

17. In a party-line telephone system,two polarized call-bells biased in opposition to each other and connected with a linecircuit for signaling, one of said bells being organized to operate with a heavy positive alternation of current to actuate its biased armature in opposition to the biasing force exerted thereon, and a light negative alternation of current to assist the biasing force in the operation of its armature in the direction of its normally bi.-

ased trend, the other call-bell being organized to operate with a heavy negative alternation of current to actuate its biased armature in opposition to the biasing force exerted thereon, and a light positive alternation of current to assist the biasing force in the operation of its armature in the direction of its normally biased trend, an alternating-current generator, a source of steady current with the negative terminal connected with the alternatingcurrentgenerator and the positive terminal adapted to be connected with the line-circuit for selectively operating the biased call-bell organized to respond to the heavy'positiye alternations, and another source of stead y current with the positive terminal connected with the alternating-current generator and the negative terminal adapted to be connected with the line-circuit for selectively operating the biased bell organized to respond to the heavy negative alternations, and means to connect either steady-current source and the alterhating-current generator with the linecircuit in the act of selectively ringing one of the bells to the exclusion of the other, substantially as described.

18. In a party-line telephone system, two polarized call-bells biased in opposition to each other and connected with a line-circuit for signaling, one of said bells being orgai'iized to operate with a heavy positive alternation of current to actuate its biased armature in opposition to the biasing force exerted thereon, and a light negative alternation of current to assist the biasing force in the operation of its armature in the direction of its normally biased trend, the other bell being organized to operate with a heavy negative alternation of current to actuate its armature in opposition to the biasing force exerted thereon, and a light positive alternation of current to assist the biasing force in the operation of its armature in the direction of its normally biased trend two alternating-current generators, and a source of positive steady current, and a source of negative steady current, means to connect one of the said generators and the positive steady current with the line-circuit for selectively operating the biased bell organized. to respond to the heavy positive al ternations, and means to connect the other generator and negative steady current with the line-circuitlor selectively operating the biased bell organized to respond to the heavy negative alternations, substantially as described.

19. In a party-line telephone system, two polarized call-bells biased in opposition to each other and connected with a line-circuit :t'or signaling, one of said bells being organized to operate with a heavy positive alternation of current to actuate its biased armature in opposition to the biasing force exerted thereon, and a light negative alternation of current to assist the biasing force in the operation of its ari'nature in the direction of its normally bisteady current with the line-circuit for selecttion to the biasing force exerted thereon, and a light negative alternation of current to assist the biasing force in the operation of its armature in the direction of its normally biased trend, the other bell being organized to operate with a heavy negative alternation of current to actuate its armature in opposition to the biasing force exerted thereon, and a light positive alternation of current to assist the biasing force in the operation of its armature in the direction of its normally biased trend, a source of steady current and means to connect either terminal with the line-circuit, a source of alternating current, the source of alternating current being connected with the central point of the steady-current source whereby a positive steady current in series with the alternating-current source or a negative steady current in series with the alternating-current source may be connected with the line-circuit for selectively operating the biased call-bells, substantially as described.

21. In a party-line telephone system, the combination with a line-circuit of two polarized bells connected therewith for selective signaling, said bells being biased by the weight of their own moving elements, one of said bells being organized to operate with a heavy positive alternation of current which will actuate its armature in opposition to the gravitational trend, and a light negative alternation of current which will assist the gravitational trend in the operation of its armature tational trend in the operation of its armature in the direction of its normal position, means connected with the line-circuit for producing the required heavy and light alternations, the means consisting of an alternatingcurrent generator and a source of steady current, the alternating-current generator and the source of steady current being connected in series whereby one alternation of the alternating current from said generator is suitably counteracted for producing the light alternation, and the other alternation of the alternating current from said generator is suitably augmented for producing theheavy alternation, and means to connect the source of steady current through the alternating-current generator in one direction to selectively ring one of the biased bells, and means to reverse the polarity of the steady current through said generator to ring the oppositely-biased bell, substantially as described.

22. In a party-line telephone system, the combination with a line-circuit of two polarized bells connected therewith for selective signaling, said bells being biased in opposition to one another by the weight of their moving elements, one of said bells being organized to operate with a heavy positive alternation of current which will actuate its armature in opposition to the gravitational trend, and a light negative alternation of cur rent which will assist the gravitational trend in the operation of its armature in the direction of its normal position, the other bell being organized to operate with a heavy negative alternation of current which will actuate its armature in opposition to the gravitational trend, and a light positive alternation of current which will assist the gravitational trend in the operation of its armature in the direction of its normal position, a source of positive steady current connected in series with analternating-current generator, and a source of negative steady current connected in series with an alternating-current generator, means to connect the alternating-current generator with the positive steady current in series, with the line-circuit to selectively ring the biased bell organized to operate with a heavy positive alternation, and means to connect the alternating-current generator with the negative steady current in series, with the line-circuit to selectively ring the biased bell organized to operate with a heavy negative alternation, substantially as described.

23. In a party-line telephone system, the combination with a line-circuit of two polarized call-bells connected therewith for selective signaling, said bells being biased in opposition to one another by the weight of their moving elements, one of said bells being organized to operate with a heavy positive alternation of current which will actuate its armature in opposition to the gravitational trend, and alight negative alternation of ourrent which will assist the gravitational trend in the operation of its armature in the direction of its normal position, the other bell being organized to operate with a heavy negative alternation of current which will actuate its armature in opposition to the gravitatinoal trend, and a light positive alternation of current which will assist the gravitational trend in the operation of its armature in the direction of its normal position, an alternating-current generator, and means to connect the generator with the line -circuit, and a source of positive steady current connected in series with the generator for producing the heavy positive alternations and light negative alternations for operating one hell, and means to reverse the polarity of the steady current for producing the heavy negative alternations and light positive alternations for operating the other bell, substantially as described.

24:. In a party-line telephone system, the combination with a line-circuit of two polarized bells connected therewith for selective signaling, said bells being biased in opposition to one another by the weight of their moving elements, one of said bells being organized to operate with a heavy positive alternation of current which will actuate its armature in opposition to the gravitational trend, and a light negative alternation of current which will assist the gravitational trend in the operation of its armature in the direction of its normal position, the other bell being organized to operate with a heavy negative alternation of current which will actuate its armature in opposition to the gravitational trend, and a light positive alternation of current which will assist the gravitational trend in the operation of its armature in the direction of its normal position, an alternatingcurrent generator, a source of steady current with the negative terminal connected with the alternating generator and the positive terminal adapted to be connected with the line-circuit for selectively operating the biased bell organized to respond to the heavy positive alternations, and another source of steady current with the positive terminal connected with the alternating generator and the negative terminal adapted to be connected with the line-circuit for selectively operating the biased bell organized to respond to the heavy negative alternations, and means to connect either steady-current source and the alternating generator with the line-circuit in the act of selectively ringing one of the bells to the exclusion of the other, substantially as described.

25. In a party-line telephone system, the combination with a line-circuit of two polarized call-bells connected therewith for selective signaling, said bells being biased by the weight of their moving elements in opposition to each other, one of said bells being organized to operate with a heavy positive alternation of current which will actuate its armature in opposition to the gravitational trend, and a light negative alternation of current which will assist the gravitational trend in the operation of its armature in the direction of its normal position, the other bell being organized to oper ate with a heavy negative alternation of current which will actuate its armature in opposition to the gravitational trend, and a light positive alternation of current which will assist the gravitational trend in the operation of its armature in the direction of its normal position, two alternating current generators, and a source of positive steady current, and a source of negative steady current, means to connect one of said generators and the positive steady current with the line-circuit for selectively operating the biased bell organized to respond to the heavy positive alternations, and means to connect the other generator and the negative steady current with the line-eircuit for selectively operating the biased bell organized to respond to the heavy negative alternations, substantially as described.

26. In a party-line telephone system, the combination with a line-circuit of two polarized bells connected therewith for selective signaling, said bells being biased in opposition to each other by the weight of their moving elements, one of said bells being organized to operate with aheavy positive alternation of current which will actuate its armature in opposition to the gravitational trend, and a light negative alternation of en rrent which will assist the gravitational trend in the operation of its armature in the direction of its normal position, the other bell being organized to operate with a heavy negative alternation of current which will actuate its armature in opposition to the gravitational trend, and a light positive alternation of current which will assist the gravitational trend in the operation of its armature in the direction of its normal position, an alternating-current generator, and a source of positive steady current, and a source of negative steady current, means to connect said generator and said source of positive steady current with the line-circuit for selectively operating the biased bell organized to respond to the heavy positive alternations, and means to connect said generator and the source of negative steady current with the line-circuit for selectively operating the biasedbell organized to respond to the heavy negative alternations, substantially as described.

27. In a party-line telephone system, the combination with a line-circuit of two polarized bells connected therewith for selective signaling, said bells being biased in opposition to each other by the weight of their moving elements, one of said bells being organized to operate with a heavy positive alternation of current which will actuate its armature in opposition to the gravitational trend, and a lightnegative alternation of current which will assist the gravitational trend in the operation of its armature in the direction of its normal rent with the line-circuit, a source of alter.

nating current, the alternating source being connected with the central point of the steadycurrent source whereby a positive steady current in series with the alternating-current source, or a negative steady current in series with the alternating-current source for producing the heavy and light alternations may be connected with the line-circuit for selectively operating the biased call bells, substantially as described.

In witness whereof I have hereunto subscribed my name in the presence of two witnesses.

THOMAS C. DRAKE.

Witnesses:

A. DURBIN, E. J. ARRIoK.

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