US1263010A - Semi-automatic telephone system. - Google Patents

Description

B. D. WiLLIS.

SEMI-AUTOMATIC TELEPHONE SYSTEM.

APPLHIATION FILED OCT-14,1913.

Patented Apr. 16, 1918.

3 SHEE'lS-SHEEI I.

B. D. WILLIS. SEMI-AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED OCT-14,1913- Patented Apr. 16, 1918.

3 SHEETSSHEET 3- Ivafax TTO/PA/EYS.

UNITED STATES PATENT OFFICE.

BERNARD D. WILLIS, OF CHICAGO, ILLINOIS, ASSIGNOR T0 AUTOMATIC ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

SEMI-AUTOMATIC TELEPHONE SYSTEM.

Application filed October 14, 1913.

To all u-liom it may ("anew/n:

lle it known that l, lit-ammo l). WILLIS, a citizen of th United States of America, and resident of thicago, (look county, Illinois, have invented certain new and use t'ul Improvements in Semi-Automatic Telephone Systems. at which the following is a. specification.

My invention relates to improvements in semi-alltoluatic telephone systems, and, it relates partieulartv to an improved trunkin;- arrangement in sueh a system and also to certain improvements in the automatic switches therein employed.

Among the novel features of my invention is the provision of a trunk line over which a call may be extended manually in either direction which trunk line is also adapted for the extension of automatic calls in one direction. This trunk line termi- Hates at one end in a manual board and at the opposite end is provided with two hranehes. one tenninatinoin an automatic tXtlltlll l't and the other terminating in a. manual board. The automatic switches at the automatic (.\'('lltlll,' are controlled over this trunk line without interfering in any way with the manual apparatus by means of the provision of phantom operated cirtlllilillltlil is. eireuits which include the two sides of the trunk in parallel. By this means, when thi. trunk is being employed to extend an automatic connection, the switches are op rated without in any Way ati'eeting the manual signals, and likewise when the trunk is being employed for the extension of -i manual connection the automatic apparatus is not affected.

1 likewise provide means for providing a guarding potential on one branch of this trunk while anet her branch of this trunk is in use.

A further feature of my invention is the provision of an improved side switch-less selector the trunk conductors of which are permanently connected with the switch wipers, together with the feature of having condensers in these talking conductors The selector is likewise provided with an extra Wiper. which is independent of the talking wipers, over which the line relay of the connector is controlled.

These and other objects and features of my invention will be readily understood by Specification of Letters Patent.

Patented Apr. 16, 1918.

Serial No. 795,146.

reference to the accompanying drawings in which I have illustrated my invention in connection with certain manual and automatic apparatus of a particular type.

Figure 1 is a diagrammatic illustration of the layout of a system in connection with which my invention is illustrated.

Figs. 22, 3 and 4, taken together, are a more detailed representation of the system. Fig. 2 shows the apparatus indicated at the left of Fig. lthat is, at section A. Figs. 3 and 4 show the apparatus contained within that part ofthe system shown at the right of Fig. t----that is, at section B.

The section A. of Fig. 1 represents a number of subscribers C whose lines terminate in a. manual hoard D, from which hoard connections may be made to the section B of the system. This last section shows a number of lines E which are accessible to a manual board I and to automatic apparatus indicated at (l. Vl hen a subscriber at C wishes to establish connection with a subscriber at E. he removes his receiver and signals the operator, who thereupon extends the connection to the B section of the system, where the eonneetion is finally completed. The eireuits are so arranged and suitable apparatus provided that the opera tor may either eomplete the connection automatically by bringinginto use the automatic apl'iaratus indicated at G (Fig. 1), or she may have the connection completed ma n uall v by an operator at the board F.

We will assume first that a subscriber H of the group (T (Fig 1) Wishes to establish connection. with a subscriber I of the group E. and that the connection is completed by the operator through the automatic appa ratus G rather than through the board F. The subscriber, upon removing, his receiver 2, energizes the line relay 3 (Fig- 2), which relay in turn causes the light -t to signal the operation, The operator thereupon inserts the plug of the .cord J into the line or answering jack of the subscriber H, thereby connecting the line circuit with the cord circuit, as shown. At the same time a. circuit is established through the cut-off relay 5 and the supervisory relay 6 in series, which causes the cutoff relay 5 to energize in the 105 usual manner, disconnecting the line relay 3 from the line, as shown, and thus breaking the circuit of the lamp 4. The relay 6, upon and lamp 7 but for energizing, would close a circuit for the sigthe fact that the relay 8 is ener ized in series with the subscribers line an with a coil 9 at the cord circuit, and in this manner the lamp 7 is prevented from being displayed at this time. The operator then throws herlistening key, which closes the springs 10 and 11 and separates the sprin 12. The closure of the springs 10 and 11 bridges the operators talking set across the line, whereupon the operator ascertains the number of the called subscriber I. We will assume this number tube 256. The operator then inserts the calling plu of the cord J into the jack K, thereby esta lishing connection with the trunk L, which terminates in the board B. A circuit is thus established through the relay13 in series with the rela 14 and with the winding 15 of the trunr signal relay 16. The relay 13, u on energizing, shifts the spring 17 from t e sprin 18 and into enga ement with the spring 19, thereby groun ing the conductor 20 and causing the multiple lamps 21, 22 and 23 to light. These lamps indicate to the other operators which have access to this trunk by means of the jacks 7c and k that the trunk is busy. The relay 13, furthermore, by se arating the s rings 24 and 25 from t e springs 26 an 27, respectively, disconnects t e winding 28 of the relay 16 from across the conductors 29 and 30 of the trunk L. Furthermore, the relay 13 by carryin the springs 24 and 25 into engagement with the springs 31 and 32, respectively, bridges the windings 33 and 34 of the phantom relay 35 across the conductors 29 and 30 of the trunk L. It will be observed that there is a connection from a point between the windings 33 and 34 through the springs 36 and 37 and through a resistance coil 38 to the battery M. The relay 13, therefore, upon energizing, has the client of connecting the non-grounded pole of the battery M with both the trunk conductors 29 and 30 of the trunk L. It will also be observed that at the board B (Fig. 3) there is another relay 39 similar to the relay 35 ,Which has its windings 40 and 41 normally across th conductors 29 and 30 of the trunk'L, and from a oint between these two windings 40 and 41-t ere isi a connection bly way of the conductor 22, which runs to t e first selector N, through a pair of springs 43 and 44 under thecontrol of the relay 745 and ,through the 'relay 46 to ground G. 'TllBlBfOIB, as soon as the battery M is bridged acrossthe trunk L through the windings of the relay 35', a simplex" circurt is establighed through the relay 46 (Fig. 3) to round G and back to the "battery M, with the result thatthe r elay 46 becomes energized. This relay, upon energizlng, carries the sprin 47 into engagement with the sprm 48, t ereby energizing the relay 49, which atter, upon energizing,

carries the springs 50 into engagement. When this circuit is closed at the point 50,

connection is extended from ground G by way of the conductor 51 and springs 52 to the oft-normal springs 53, which are nor mally open. It will be observed, therefore, that the result of the operator inserting the calling plug of the cord J into the jack K is to put the line relay 16 of the selector N in readiness for receiving impulses from a calling device 0 under the control of the opera tor (Fig. 2), which calling device comprises the springs 36 and 37. This calling device is of the same general character as the callingidevice described in British patent to S. G. S. Dicker No. 29,654 of 1910. The circuits are now in readiness to respond to the action of the calling device 0 when it is op closed until after the springs 36 and 37 he we produced impulses corresponding to the digit being called, which in this particular case is 2. The object in having the relay energized as soon as the dial. leaves normal I is to have it press into contact the springs 56, 57 and 58 for the urpose of short-circuiting the windin s of? the relay 35, so that the springs 36 an transmitting much stronger impulses to the line relay 46 of the selector N than would otherwise be the case. The line relay 46 at the selector N will respond to the operation of the calling devicethat is, each time the springs 36 and 37 separate, the relay 46 deenergizes, "ermitting the spring 47 to fall back. Eaci time that the spring 47 falls back it sends an impulse through the slow acting auxiliary relay 59 and through the vertical magnet 60 in series from ground G through the springs 47 and 61, springs 62 (under the control of the relay 45) and the springs 63 and 64 (under the control. of the relay 49), and through the relay 59 and vertical magnet 60 to battery. These impulses energize the vertical magnet 60 twice,'which operates to raise the switch shaft two steps. The relay 59 energizes while these impulses are being transmitted, carr ing the 5 rings 65 and66 into contact, an as a resu t setting up a ircuit through the quick auxiliary relay 67 from ground G through said 37 may be capable of spring 69 and into engagement with the nrating the interrupter springs 73 and as follows: Upon the spring 70, in which condition thesaid springs 68 and 70 are maintained until the switch N finds an idle trunk.

first vertical step of the switch shaft as a result of the action. of the vertical magnet 60, the oti-normal springs 53 close in contact, thereby ctmu'ilcting another energizing circuit for the relay 67 by way of its own springs 68 and 70, the otfnormal springs 53, the rotary magnet interrupter springs and the springs 50 to ground G. After the line relay 40 sends in the last impulse for the first. digit 2, the usual pause follows, during which time the spring 47 remains disengaged from the spring 61. and as result causing the auxiliary slow art ing relay 5.) to dpiinergize. The relay 5!), upon detinergizing, breaks the original energizing circuit for the quick acting auxiliary relay (57', which was closed by way of ground ti. Hoax-aver, the relay (37 does not tlei ru'srgize, because it. is maintained onergized over the circuit already tracedpvhieh is cstal'ilished through ground G The relay 59,11111112 dei nergizing. notonlydiseonueetisthc original energizing circuit for the relay 67, but; by permitting the spring 65 to engage the spring 71 loses an enrrgizing circuit for the rotary magnet 72, which causes the switch N to start; on its rotary nloven'ient in Search of an idle trunk. This energizing circuit cxtends from ground G (under the control of the release relay 49) through the springs 50, rotary magnet interrupter springs 52, 0th normal rings 53, springs 68 and 70, springs 65 and (1. through a second set of interrupter springs 73 (under the control of the rotary nmgnet) and through the rotary magnet 72 to battery M. The rotary magnet, upon energizing, rotates the shaft wipers in the usual manner, carrying them into on gagement with the first set of contacts in the second level. Vl e will assume that when the wip rs are rotated, the first trunk which they liud is busy, and we will explain how the switch auton'iatieally mtates onto the second trunk terminating in the connector switch F, which, it will be assumed is idle. It will be observed that the quick acting auxiliary relay 67 is now supplied with a new energizing circuit as long as the private wiper 74 meets theprivate contact of a busy trunk, which is, under such condition, connected to ground, this circuit extending over the L'OlHlllCiCll 5%? to' the private wiper 74. The rotary magnet. 72, upon drawing up its armature as a result, of the closure of the circuit through ground (1 interrupts not; only its own energizing circuit, but by sepalso interrupts the energizing circuit for the magi'iet 67 which was described as passing through the springs 52 to ground G However, the relay 6? does not deiinergize, because the third energizing circuit which has This is accomplished- .eireuit through been described as extendin through the private wiper 74. prevents it from so doing. When the armature ot' the rotary magnet returns to normal position, the original eir-- units for both the rotary magnet and the relay G7 are restored through ground (i and the rotary magnet 72. again energizes, again breaking its own circuit, as well as the circuit of the relay til at the interrupter springs 73 and 532. The shaft 75 and the wipers 7(5, 74.. 77 and 78 are rotated one more step onto the next trunk, which it has been tlfinttlilttl is idle. The result is that the third and last energizing circuit for the relay 67 is broken, whereupon the relay 6? dei nergizes, thereby preventing the rci stablishnlent of its own rireuit and the circuit of the rotary magnet 72 through ground ti" when the armature of the rotary magnet returns to normal posi tion, The result; is that the switch stops on the idle trunk terminating in the switch P. The relay 6?, however, by (leihiergizing and permitting the springs 68 and ti!) to thereby t'lust', closes a circuit; for the switching relay to as soon as the interrupter springs 52 of the rotary magnet close contact. This energizing circuit extends fr m ground l through tin-springs 5t conductor .11. springs 52. elf-normal spring 53, spriiigs 13S and (t9 and through said switching relay 45 to l'iattery. The relay 45, upon thus energizing, opens the circuit of the line to lay -16 at the spring 44 and also opens the the slow acting auxiliary relay 59 at the springs 62. 1t furthermore cuts through the connection from the line 42 to the conductor 79 and by way of the wiper 7? to the line relay 8() of the connector switch P, thereby substituting the line relay 80 for the line relay 46 in the circuit controlled by the calling device (Pig. 2), which circuit extends from ground G through said relay 80, wiper 77 and the springs 81 and 43 to the conductor 42, and from thence on to the apparatus in F lg. 52, as already explained. When the circuit of the line relay 46 is broken, this relay deenergizes, in turn causing the detinergization of the release relay 49. Under certain conditions this relay 49, upon dei nergizing while the relay 46 1S deiinergized, would close the energizing circuit for the release magnet 82, since as soon as the shaft is raised, the release magnet 82 is connected by the otf--t'io1'mal springs 83 with the spring 84 under the control of the said release relay. This circuit of the release magnet like wise includes the contacts (32 under the control of the switching relay 45. Since the switching relay 45 is energized, the circuit. that would be established through said release magnet from ground G is interrupted at the springs 62. I will now explain how the relay 45 is maintained energized even after the release relay 49 denergizes. As

soon as the line relay 80 of the switch P ener izcs over circuits already pointed out, it shifts the spring 83 into engagement with the spring 84, thereby completing a circuit for the release relay 85 from ground G". The relay 85, upon energizing, closes contact at the springs 86, thereby connecting ground G with the conductor 86. From this point on a circuit continues through the private wiper 74- and the conductor 87, through the springs 68 and 69 (under the control of the quick acting auxiliary relay 67), to and through the switching relay 45 to battery. It will be observed that this same circuit from ground G", after passing through the springs 68 and 69 of the quick acting auxiliary relay 67, extends by way of the conductor 88 to the relay 89 in the manual board B and thence to battery. The relay 89, upon energizing, carries the spring 90 into engagement with the spring 91, thereby connecting ground G with the condoctor 92 and lightmg the lamps 93 and 94. as a signal to the operators at the B board that the trunk L is busy. The operator is now ready to operate the calling device 0 for the second digit 5 of the desired subscribcr. \Vhen she does so the line relay 80 responds five times in the same manner as the line relay '16 responded twice for the first digit 2'. Since the relay 85 is energized, and the springs 95 and 96 in contact, each time the relay 80 decnergizes and carries the spring 83 into engagement with the spring 9 an impulse is sent through the private magnet relay 98v and the vertical magnet 99 in series. The vertical magnet is then energized five times, raising the switch shaft 100 and the shaft wipers 101, 102 and 103 five steps to the fifth level. It will be understood that while these impulses are being transmitted, the side switch Wiper 104: is in first position, which position is indicated by the dotted lines, and during the same period the slow acting private magnet relay 98 remains energized. Upon energizing,

. this relay 98 closes a circuit for'the private magnet 105 from ground G through the springs 106and 107 and through the private magnet 105 to batter The private magnet remains'energize as long as the relay 98 remains energized, but during the pause that follows the second digit 5 after the five impulses have been transmitted, the line relay 80 remains energized and as a result the private magnet relay, 98 falls back, breakin the circuit for the private magnet 105, which operates to tripthe side switch from first to second'position, thereby carrying the side switch wiper 104 into engagement with the contact 108 and the side switch wiper 109 into en agement with the contact 110. It will be 6 served that when the switch shaft100 is raised the first step, a circuit is closed at the contacts 111 and another at the contact 112. The closure of the contacts 111 extends the circuit of the release ma et 113 to the spring 114, under the oontro of the release relay 85, and the closure of the contact 112 repares the circuit of the relay 115, which is completed after the side switch wiper 109 passes from first to second position and en ges the contact 110, provided the called line is busy, as will be explained. The apparatus is now in condition to receive the mepulses corresponding to the third digit 6. The line re lay 80 responds as before and causes the operation of the rotary magnet 116. The impulses through this magnet ass from ground Gr through the relay 8, thence through the rotary magnet 116 and through the side switch wiper 104, which is now 1n second position, to battery M. The rotary magnet 116 operates to rotate the switch sha't't and wipers along the fifth level, during which interval the rivate magnet relay 98 is energized; and t erefore the private magnet 105 is also energized, due to the closure of contacts of the s rlngs 106, and 107, under the control of sai relay 98. The relay 105, being energized, breaks the talking conductors which are shown in hea black lines by separating the contacts 11 and also by separating the contacts 118. The object in thus opening the talking circuit is to revent the switch P from interfering with any lines that may be busy as it passes over the six impulses correspondin to the last di '1: have been transmitted, the wipers of t e connector switch are found on the contacts of the desired line I (No. 256) shown in Fig. 1. After the impulses have ceased operating the relay 80, the rivate magnet relay 98 deenergizes, as in t e previous instance, permitting the private magnet 105 to de'e nergize and causing the side switch wipers 104 and 109 to pass to third position, as indicated in full lines. As soon as this occurs, the cut-ofi relay 118 of the called line is energized over a circuit extending as follows: From ground Gr through the conductors 120, private wiper 102, side switch wiper 109, resistance coil 119, conductor 121 and to battery Q (Fi 4). The relay 118, upon energizing, cuts 0 the signal relay 122 to prevent the same from ener izing when the called subscriber answers. he connection of battery Q throu h the conductor ,121 with the conductor 1 0 and the }sleeves 128 of'the jacks of the called line is t e tentiu} at said sleeves when t e connector P establishes. connection with the line I.

When connection is thus established between the' cord J and the telephone I, the subscriber at the telephone 1 maybe aignaled b the operator throwing the ringing key an there y shifting the springs 12 edium for providin guarding porelease relay 4!) and 94, in this manner and 1:25 into engagement with the contacts 121? and 127, which latter are connected with the ringing generator B.

After the subscriber, are through talking, they hang up their receivers and signal the operator at J, who takes down the connection. This signal is given when the lamp 7 is displayed as a result of the deli]iergizml tion of the relay 8 when the subscriber H breaks the circuit at the switch, hook. The operator, upon receiving the signal, takes down the cord, which restores the circuits of the called line and causes the line relay 80 of the connector P to be deiinergized, whereupon the circuit of the release relay 85 is broken. This relily, as a result, brings the springs 96 and 114 into contact, and springs 97 and 83 are now in engagement, the is energized. The release magnet restores the switch P in the usual manner, and when the wipers leave the contacts of the called line, the apparatus of the called line is restored to normal. When the release relay at the connector was deencrgized, it not only caused the release of the connector l, but by breaking the circuit at the contacts 86 caused the decncrgization of the switching relay 45 in the selector N, causing this automatic switch to release also. It will be seen that, when the relay 45 denergizes it permits the springs 62 to come into contact, thereby closing the energizing circuit for the release magnet 82, which circuit, as has been previously pointed out, would have been closed when the line relay 46 and the deinergized at the time was extended from the connector P but for the relay 15 at the same at: the point 62. The

the connection switch N to the fact "It the switching time opened the circuit energizing circuit for the release magnet may be traced from ground G through the line relay springs 4.7 and 1, springs 62, springs 63 and 94, through the off-normal springs 83 and thence through the release magnet 82 to battery. The release magnet, upon energizing, of course removes the hold ing pawls from the switch shaft, causing V the said shaft to return to normal position. it may be well to state that the mechanical details and operation of the switches N and l are of the same general character as those of the selectors and connectors disclosed in l nitcd States Letters Patent Nos. 815,321 and 815,176, granted March 13, 1906, to Keith, Erickson and Erickson. It will be seen that the deiinergization of the relay 85 likewise breaks the energizing circuit of the relay S9 at the board B and that: the relay 89 breaks the circuits of the lamps 93 I removing the busy signals for the trunk L.

Assuming that the stdiscl'ibeWs line is easy when the wipers of the connector P release magnet 113 v engage the contacts of the called line, then the private wiper 102 finds a guarding potentxal from the non-grounded terminal of the battery Q on the private bank contact of this line, said potential reaching such private contacts by way of the conductor 120 in the manner previously described. As a result, the side switch of the connector being at the time in second position, the relay 115 is energized by a flow of current from battery Q to the conductor 120, thence by way of the private wiper 102 to the side switch wiper 109 and contact 110, through the relay 115, through the springs 124 and 125 and the ofl'normal springs 112 to ground G". When the relay 115 becomes thus energized while the side switch of theconnector 15 in second position, it presses the springs 126 and 127 into contact, and as soon as the private magnet relay 98 dci nce gizcs after the impulses for the last digit have been transmitted, the busy locking relay 128 energizes in series with the private magnet 105 by way of the contacts 107 and 129 under the control of the relay 98. prevents the private magnet. 105 from decnergizing and therefore prevents the calling line from being cut through to the called lYhen the busy locklng relay 128 euergizes it does not break the energizing circuit of the relay 115, because the spring 130 engages the spring 125 before the latter leaves the ring 124. and the switch is maintained in this locking condition until the subscriber or the operator, or both, receive the busy signal, which is automatically sent to the operator and the calling subscriber when the locking relay 128 presses the springs 131 and 132 into contact. The busy signaling current, of course, originates in the busy signaling apparatus T. n order to prevent the operator from operating the rotary magnet any farther. the locking relay 128 is provided with a couple of springs 133 which, when the relay 128 energizes, breaks the energizing circuit of the rotary magnet 99. When the operator receives the busy slgnal, or when she receives the disconnect signal as a result of the busy signal, she releases the connection as before.

Having explained how a connection is established by the use of auton'iatic apparatus when the sul'iscriher [-1 Wishes to call the subscriber I, it will now be explained how the connection might be completed without the automatic apparatus and through the manual exchange B. The operator (Fig. 2), upon receiving the signal from the subscriber .11, extends the connection to the B exchange, not by plugging into the jack K, but: by plugging into one of the jacks When the operator does this she causes the relay 13a to energize instead of the relay 13, as before. This energizing circuit extends from battery M through the sleeve of the jack is" and by way of the conductor 135 through the relay 134 and through the winding 15 of the relay 16 to ground G The relay 134, upon energizing, disconnects the winding 28 of the coil 16 from across the trunk L by breaking the contacts 136 and 137 and at the same time, by shifting the spring 138 into contact with the spring 139, connects the conductor 20 to ground G to thereby light the lamps 21, 22 and 23, to indicate that the trunk L is busy. The operator is now ready to signal the operator at the board B, which is done by shifting the springs 124 and 125 onto the contacts 126 and 127. Ringing A current is thus transmitted from one side of the generator B through the contacts 126 and 124, one side of the cord circuit to the tip of the plu trunk conductor 29, contact springs 14 0% the relay 145, windings 40. and fil of the phantom coil 39 in series, contacts 146, trunk conductor 30 and the opposite side of the cord circuit through the contacts 125 and 127 to the opposite side of the generator B. This ringing current operates to energize the relay 39 which, upon energizing, closes the contact 141, thereby closing an energizing circuit through the winding 142 of the signal relay 143, this circuit extending from ground G, under the control of the relay 89, throu h the springs 90 and 14 1, thence through t 1e s rings 141 and through the winding 142 to attery M.

The operator B, 11 receiving the signal, plugs into the jac PU with the plug of a cord circuit similar to-=that shown at S (Fig. 4:), restoring the drop 143-and energizing the relay 145. This circuit extends from the non-grounded pole of the battery Q, sleeve contact of the plug and jack, contacts 191, controlled b the relay 89, relay 145 and restoring win ing of the si nal relay 1i3 to ground G. The relay 1 5, upon energizing, disconnects the coil 39 from across the trunk L by separating the contacts 146 and 147 and at the same time, by

shifting the spring 148 into engagement with the spring 149, closes a circuit through the lamps 93 and 94 from ground G". The operator at the board B completes the connection in the usual manner. versation between the subscribers is terminated, the subscribers H and I signal their respective operators to take down the connections and restore the apparatus.

If the subscriber I wishes to establish connection with the subscriber H, the subscriber I will signal the operator at the B board in the usual manner, who, through the medium of a cord circuit such as the cord circuit S, extends connection by way of the trunk L with the board A. The operator, the cord S into the jack U, thereby energizing the relay 145, which operates the After the coni for example, inserts the plug of same as in the revious instance to disconnect the coil 9 from across the trunk and at the same time operates to light the lamps 93 and 94 to indicate that the trunk L is busy. The operator then sends ringing current over the trunk line L through the winding 28 of the signal relay 16 (Fig. 2) thereby signaling the operator at the board A. The operator at the board A then comletes the connection with the subscriber H in the usual manner. When the subscribers are throu h talking, each signals his operator and t ese operators take down the connection. If for an reason the operator at the board A neg acts to take down her connection, the operator at the board B can signal the operator at the board A by transmitting ringing current over the trunk'to thereby energize the relay 156, which, upon energizing, causes the lamp 14.7 to light, thereby signaling the A operator.

It will thus be seen that I have devised a very efiicient system in which an operator at one exchange, when it is desired to estab-' hsh a connectlon with a subscribers' 11119 which terminates in a second exchange, can extend this connection over a trunk line to a second exchange and then extend the connection to the desired line either automaticall or manuall by means of an operator at t e second exc ange. Likewise, the operator at the second exchange can employ the same trunk for extending a connection manually from the second exchange to thefirst exchange. Furthermore, when this trunk is in use for any one of these connections, suitable guarding potentials are provided to prevent either one of the operatorsemployin the trunk for any other connection. Likewise, it will be seen that the line relay of the connector is operated over a circuit which is independent of the talking circuit, both. the selectors and con.- nectors being controlled over a'simplex circuit which includes the two sides of the trunk in arallel with a ground return.

While I have illustrated and described certain specific embodiments of my invention, it will be understood that in its broader aspect the two-way trunk line could be employed with other forms of antomatic switches, and-likewise that the fog.-

ture of my invention having automatic.

switches controlled in this manner over two sides of a trunk in series is capable of use with other forms of trunk circuits and other automatic or semi-automatic systems. Various other changes and modifications will readil suggest themselves to those skilled in t e art, which modifications come within the contemplated scope of my invention.

In various places in the specification and in the claims in this application I have referred to a simplex circuit. By simplex circuit is meant that section of a phantom circuit which is left when one of the physical branches of said phantom circuit is reduced to a single conductor.

What I claim as my invention is 1. In a telephone system, a two-way trunk line, means including perators equipment and call signals for manually extending connections over said trunk in either one of two directions, an automatic switch at one end of said trunk, and means for operating said switch over said trunk to extend a con nection thcreover semiautomatically.

2. In a telephone system, a manual board, a trunk line terminating in said board, a pair of branches for the opposite end of said trunk, one'branch terminating in an automatic switch and the second branch terminating in a second manual board, means for controlling said automatic switch over said trunk line, a signal associated with said second manual board, and means for operating said signal over said trunk line.

3. In a telephone system, a trunk line, means for seizing one end of said trunk, a pair of branches for the opposite end of said trunk, an automatic switch connected with one of said branches, a manual jack associated with the other of said branches, a signal associated with said jack responsive to calls over said trunk line, and means for operating said switch over said trunk withoutoperating said signal.

4. In a telephone system, a trunk line, means for seizing one end of said trunk, a pair of branches for the opposite end of said trunk, an automatic switch connected with one of said branches, a manual jack associated with the other of said branches, :1 signalassociatcd with said jack, means for operating said switch over said trunk with out operating said signal, and means for operating said. signal over said trunk without operatin said automatic switch.

5. In a te ephone system, a trunk line, means for seizing one end of said trunk, a pair of branches for the op iosite end of said trunk, an automatic switc ,connected with one of said branches. a manual jack associated with the other of said branches, a signal associated with said jack and operable over said trunk line, means for operating said switch over .aid trunk without operatinn said signal, and means for revcnting Sttlt trunk line being employed or establishing one connection when it is employed in establishing a second connection.

G. In a telephone system, a trunk line, means for seizing one end of said trunk a pair ol branches for the opposite end of said trunk, an automatic switch connected with one of said branches, a manual jack assoeluted with the other of said branches, a signal associated with said jack, means for oplines divided into crating said switch over said trunk Without operating said signal, means for operating said signal over said trunk without operatjn, said automatic switch, and means for preventing said trunk line being employed for establishing one connection when it is employed in establishing a second conned lion. v

7. In a telephone system, a manual operators cord circuit, atrunlr line having a terminal adapted to be connected with said cord, a pair of branches for the opposite end of said trunk. an automatic switch associated. with one of said branches. a manual terminal associated with the other of said branches, a signal associated with said manual terminal to indicate incoming calls, and means by which the operator at said cord circuit can control the operation of said automatic switch over said line without operating said signal.

In a telephone system, a manual operators cord circuit, a trunk line having a terminai adapted to be connected with said cord, :1 pair of branches for the opposite end of said trunk, an automatic switch associated with one of said branches, :1 manual terminal associated with the other of said branches, a signal associated with said manual terminal, means bywhich the operator at said cord circuit can control the operation of said automatic switch over said line without operating said signal, and means by which said operator can operate saidsignal without operating said automatic switch.

9. In a telephone system, an automatic switch, a plurality of trunk lines divided into groups, said switch having one motion to select groups and a second motion, to find a line in the selected roup, and noxrdifl'erential means energize over the two sides of a line circuit in parallel, for controllingthe operation of said switch. V

10. In a telephone system, a subscribers line, an automatic switch, means including a trunk line for extending'a connection from said line to said switch, a plurality of trunk groups extending from said switch. said switch having onemotion to select groups and a second motion to find a line in a selected group, and non-differential means energized over the two sides of said first-mentioned trunk in parallel, for controlling said switch.

11. In a telephone system, a trunk line, an automatic switch in which said trunk terminates, a group of trunk lines extending from said switch, and nolrdilferential means energizcd over the two sides of said first-mentioned trunk in parallel for controlling Said switch to connect with an idle one of said group of trunks.

12 ,In a telephone system, a trunk line, no automatic switch in which said trunk terminates, a bridge, electromagnetic means to a source of current controlling the connection of said bridge across the opposite end of said trunk, a source of current connected to the mid point of said bridge, and means for controlling the operation of said switch by controlling the connection of said source of current to said bridge.

13. In a telephone system, a trunk line, an automatic switch in which said trunk terminates, a bridge, electromagnetm means controlling the connection of said bridge across the opposite end of said trunk, a source of current connected to the mid point of said bridge, means for controlling the operat on of said switch by controlling the connection. of said source of current to said bridge, and a plurality of groups ot trunk lines extending from said switch, said switch having one motion to select groups and a second motion to find a line in a selected group.

14. In a telephone system, a trunk line, an automatic switch in which said trunk terminates, a bridge across the opposite end of said trunk, a, resistance in said bridge, a connection from the mid point of said bridge to a source of current, means for controlling said switch by controlling the connection of said source of current to said bridge, and means for 'short-circuiting said resistance while said switch is being operated.

15'. In a telephone system, a trunk line, an automatic switch in which said trunk tenni nates, abridge across the opposite end of said trunk, a resistance in said bridge, a connection from the mid point of said bridge means for controlling said switch by controlling the connection of said source of current to said bridge, means for short-oircuiting said resistance while said switch is being operated, and a lurality of roups of trunk lines extending rom said switch, said switch having one motion to select groups and a second motion to find a line in a selected group.

16. In a telephone system, a trunk line, an automatic switch in which said trunk terminates, a bridge across the opposite end of and J-runk, a source of current normally connected to a mid oint of said bridge, and means for contro mittently breaking the connection-of source of current with said bridge.

17. In a telephone s stem, a trunk line, an automatic switch in w ich said trunk terminates, a bridge includin a resistance across the opposite end of sai trunk, a source of current normally connected to the mid point of said bridge, means for controlling said switch'by interm'ttently breaking the connection of said source of current with said bridge, and means for short-circuiting said resistance while said switch. is being operated.

18. In a telephone system, a manual exchange, a second exchange, subscribers lines said ing said switch by lIliZBI'- terminating in said second exchange, a trunk line terminating in said first exchange and extending to said second exchange, means for manually cxtciidin a connection from said trunk line to a su scribers line terminating in said second exchange, and automatic means controlled over two sides of said trunk line in parallel for extending a connection from said trunk line to a subscribers line terminating in said second exchange.

19. In a telephone system, a manual board, a trunk line terminating in said board, a pair of branches for the opposite end of said trunk, one branch terminating in an automatic switch and the second branch terminating in a second manual board, means for controlling over two sides of said trunk line in parallel, a signal associated with said second manual board, and means for operating said signal over a circuit, including two sides of said trunk line in series.

20. In a telephone system, a trunk line, a bridge across one end of said trunk, a second bridge across the opposite end of said trunk, an automatic switch having a line relay adapted to be connected to the mid point of one of said bridges, a source of current adapted to be connected to the mid. point of the other of said bridges, and means for controlling the connection of said source of current to said second bridge to thereby control the operation of said auto matic switch.

21. In a telephone system, a trunk line, a pair of resistance coils bridged across said trunk, a second pair of resistance coils bridged across the opposite end of said trunk, an automatic switch having a line relay adapted to be connected to one of said bridges at a point between said resistance coils of that bridge, a source of current adapted to be connected to a point between the resistance coils of the other of said bridges, and means for controlling the con nection of said source of current to said last-mentioned bridge to thereby control the operation of said automatic switch.

22. In a telephone system, a trunk line, a pair of resistance coils bridged across said trunk, a second pair of resistance coils bridged across the opposite end of said trunk, an automatic switch having a line relay adapted to be connected to one of said bridges at a point between said resistance coils of that bridge, a so'drce of current adapted to be connected to a point between the resistance coils of the other of said bridges, means for controlling the connection of said source of current to said lastmentioned bridge to thereby control the operation of said automatic switch, and means for short-circuiting said last-mentioned resistances while said switch is being operated.

said automatic switch 23. In a telephone system, a trunk line, a

br: e across one end of said trunk, a sec,

,en'd.i fridge across the opposite end of said adapted to be connected trunk; an automatic switch having a line relay adapted to be connected to the mid point of one of said brid es, a source of current adapted to b 001 nccted to the mid point of the othe of said bridges, means for controlling the connection of said source of current to said second bridge to thereby control the operation of said automatic switch, and a plurality of trunk lines divided into groups, said switch having one motion to select groups and a second motion to connect with a line in a selected group.

24. In a telephone system a trunk line, a pair of resistance coi-ls br'dged' across said trunk, a second pair 0 resistance coils bridged across the opposite end of said trunk, an automatic switch having a line relay adapted to be connected to one of said bridges at a point between said resistance coils (if that bridge, a source of current adaptedto be connected to a point between the resistance coils of the other of said bridges, means for controlling the connection of said source of current to said lastmentioned bridge to thereby control the operation of said automatic switch, and a plurality of trunk lines divided into groups, said switch having one motion to select groups and a second motion to connect with a line in a selected group.

. 25. In a telephone system, pair of resistance coils bridged across said trunk, a second pair of resistance coils brid ed across the opposite end of said truni, an automatic switch having a line relay adapted to be connected to one of said bridges at a point between said resistance coils of that bridge, a source of current adapted to be connected to a point between the resistance coils of the.other of said bridges, means for controlling the connec tion of said .source of current to said last mentioned bridge to thereby control the operation of said automatic switch means for short-circuitingsaid last-mentioned resistances while said switch is being 0 erated, and a plurality of trunk lines dividbd into groups, said switch having one motion to select oups and a second motion to connect with a line in a selected group.

26. In a telephone system, a trunk line, a bridge across one end of said trunk, a second bridge across the opposite'end of said trunk, an automatic switch having a line relay to the mid point of one of said bridges, a source of currentadapted to be connected to the mid point of the other of said brid es, means. for controlling the conncction 0 said source of current to said second bridge to thereby control the operation of said automatic switch, a second automatic switch,with which said first autoa trunk line, a

pair of matic switch is adapted .to establish connection, a line relay for said second switch, and means for disconnecting said first line relay and connecting said second line relay to said bridge when said first switch establishes connection with said second switch.

27. In a telephone system, a trunk line, a bridge across one end of said trunk, a second bridge across the opposite end of said trunk, an automatic switch having 'a line relay adapted to be connected to the mid point of one of said bridges, a source of current adapted to be connected to the mid point of the other of said bridges, means for controlling the connection of said source of current to said second bridge to thereby control the operationof said automatic switch, a second automatic switch with which said first automatic switch is adapted to establish connection, a line relay for said second switch, and means for disconnecting saidfirst line relay and connecting said second line relay to said bridge when said first switch establishes connection with said sec ond switch, the connection with said second line relay being independent of the talking circuit.

28: In a telephone system, a trunk line, a pair of resistance coils bridged across said trunk, a second pair of resistance coils bridged across the opposite end of said trunk, an automatic switch having a line relay adapted to be connected to one of said bridges at a point between said resistance coils of that bridge, a source of current adapted to be connected to a point between the resistance coils of the other of said bridges, means for controlling the connection of said source of current to said lastmentioned bridge to thereby control the operation of said automatic switch, a second automatic switch with which said first automatic switch is adapted to establish connection, a line relay for said second switch, and means for disconnecting said first line relay and connecting said second line relay to said bridge when said. first switch establishes connection with said second switch.

29. In a telephone system, a trunlr line, a resistance coils bridged across said trunk, a second pair of resistance coils bridged across the opposite end of said trunk, an automatic switch having a line relayadaptedto be connected to one of said bridges at a point between said resistance coils of that bridge, a source of current adapted to be connected to a point between the resistance coils of the other of said bridges, means for controlling the-'con nection of said source of current to said last-mentioned bridge to thereby control the operation of said automatic switch, means for short-circuitin said last-mentioned resistances while sai bridge is being 0 erated, a second automatic switch with which said first automatic switch is adapted to establish connection, a line relay for said second switch, and means for disconnecting said first line relay and connecting said second line relay to said bridge when said first switch establishes connection with saiflsecond switch.

30. In a telephone system a trunk line, a pair oftresistance coils bridged across said trunk, a second pair of resistance coils brid ed across the opposite end of said trun an automatic switch having a line relay adapted to be connected to one of sai bridges at a point between said resistance coils of that bridge, a source of current adapted to be connected to a point between the resistance coils of the other of said bridges, means for controlling the connection of said source of current to said last-mentioned bridge to thereby control the operation of said automatic switch, a second automatic switch with which said first automatic switch is adapted to establish connection, a line relay for said second switch, and means for disconnecting said first line relay and connectin said second line relay to said bridge w ien said first switch establishes connection with said second switch, the connection with said second line relay being independent of the talking circuit.

31. In a telephone system a trunk line, a pair of resistance coils bridged across sai trunk, a second pair of resistance coils brid ed across the opposite end of said trun an automatic switch having a line relay adapted to be connected to one of said bridges at a. point between said resistance coils of that bridge, a source of current adapted to be connected to a point between the resistance coils of the other of said bridges, means for controlling the connection of said source of current to said last-mentioned bridge to thereby control the operation of said automatic switch, means for short-circuiting said last-mentioned resistances while said switch is being operated, a second automatic switch with which said first automatic switch is adapted to establish connection, a line relay for said second switch, and means for disconnecting said first line relay and connecting said second line relay to said bridge when said first switch establishes connection with said second switch, the connection with said second line relay being independent of the talking circuit.

32. In a telephone system, an automatic selecting switch, an automatic connector switch with which said selector is adapted to establish connection, a line relay for said connector, a pair of line wipers and a third wiper for and selector, and means for conling said connector line relay over a circuit including said third wiper.

33. In a telephone system, a selector and a connector switch, said selector being adapted to extend connection to said connector, a line relay for said connector for controlling the operation thereof, a pair of line wipers, a test wiper and a fourth wiper for said selector switch, and a circuit for said line relay including said fourth wiper.

34. In a telephone system, a connector switch, a trunk line extending to said switch, said trunk comprising a pairof talking conductors, a testin conductor, a fourth conductor, a line re ay for said switch, and a circuit therefor including said fourth conductor.

35. In a telephone system, a line, a simplex circuit associated with said line, a rclay, a normally inoperative oJer-ating circnit for the relay involving sai line and the simplex circuit, an impulse sender, and a battery for operating said relay, said simpleX circuit having two terminal bridgefor bridging the line circuit, and controlling the sections electromagnetic means for connection of said bridge sections.

36. In a telephone system, a line, a simplex circuit associated with said line, a re lay, a normally inoperative operating circuit for the relay involving said line and the simplex circuit, an impulse sender, and a battery for operating Said relay, said sinr plex circuit having two terminal bridge-sections for bridging the line circuit, each bridge consisting of a resistance conductor, to the mid-point of which the simplex circuit is connected and electromagnetic means for controllingt e connection of said bridge sections.

37. In a telephone system, a line, a simplex circuit associated with said line, a rt lay, a normally inoperative operating cir cuit for the relay involving said llllt and the simplex circuit, an in'ipulse sender, a but tery for operating said relay, said simplex circuit having two terminal bridge-sections for bridging the line circuit, each bridge consisting of a resistance conductor, to the mid-point of which the simplex circuit is connected, and automatic electromagnetic means for connecting and disconnecting said terminals across the line.

38. In a telephone system, a line, a simlex circuit associated with said line, a reay, a normally inoperative operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a bat tery for operatin" said relay, said simplex circuit having two terminal bIldgO-SOCiltmS for bridging the line. circuit, each bridcy consisting of a resistance conductor, to llu' mid-point of which the simplex circuit is connected, and automatic electromagnetic means for automatically connecting and disconnecting said terminals across the line.

39. In a telephone system, a line, a simplex circuit. associated with said line, a reay, a normally inoperative operating circuit for the relay involving said line and the simplex circuit, an im use sender, a battery for operating sait relay, said simplex circuit havin two terminal bridge-sections for bridging t 1e line circuit, electromagnetic means for controlling the connection of said bridge sections, means for seizing said line, and electromagnetic means responsive to said seizure for rendering said relay responsive to said impulse sender.

40. In a telephone system, a line, a simlex circuit associated with said line, a reay, anormally inoperative operating circuit for the relay involving said line. and the simplex circuit, an impulse sender, a bat tery for operating said relay, said simplex circuit having two terminal bridgescctions for bridgingthe line circuit, each bridge consisting of a resistance conductor, to the mid-point f which the simplex circuit is connected, electromagnetic means in! disconnecting said bridge sections. means for seizing said line, and clectromagnclic means responsive to said seizure for renderii'ig said relay responsi e to said impulse sender.

41. In a telephone system, a line, a simlex circuit associated with said line, a reay, a normally inoperative operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battiery for operating said relay, said simplex circuit having two terminal bridge-sections and electromagnetic means for bridging said sections across the line circuit, a phi-- rality of circuits, and a progressively movable switch associated with said circuits and controlled by said relay to extend a con nection from said line to any one of said circuits.

42. In a telephone system, a line, a simlex circuit associated with said line, a. re-

ay, a normally inoperative operating circuit for the relay involving; said line and the simplex circuit, an impulse sender. a battery for operating said relay, said simplex circuit having two terminal. lll'ldflQ-SRCHOIIS,

electromagnetic means for bridging said sections across the line circuit, each bridge consisting of aresistance conductor, to the mid-point of which the simplex circuit is connected, a plurality of circuits, and a progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of'said circuits.

43. In a telephone system,a line, a simlex circuit associated with said line, a reay, a normally inoperative operating circuit for the relay involvin said line and the simplex circuit, an impu so sender, a hattery for operating said relay, said simplex circuit having two terminal bridge-sections, electromagnetic means for bridging said sections across the line circuit, ear-h bridge consisting of a resistance conductor, to the mid-point of which the simplex circuit is connected, means for connecting and disconnecting one of said terminals across the line. a plurality of circuits, and a progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said circuits.

H. In a telephone system, a line, a simplex circuit associated with said line, a relay, a normally inoperative o crating circuit for the relay involving said iine and the simplex circuit, an impulse sender, a battery for operating said relay, said simplex circuit having two terminal bridge-sections, electromagnetic means for bridging said sections across the line circuit, each bridge consisting of a resistance conductor, to the mid-point. of which the simplex circuit is connected, meant? for automatically connecting and disconnecting one of said terminals across the line, a. plurality of circuits, and a progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said circuits.

45. In a telephone system, a line, a. simplex circuit associated with said line, a relay, a normally inoperative operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operating said relay, said simplex circuit having two terminal bridge-sections for bridging the line. circuit, each bridge consisting of ,a resistance conductor, to the mid-point of which the simplex circuit is connected, means for connecting and disconnecting said terminals across the line, a plurality of circuits, and a progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said circuits.

46. In a telephone system, a line, a simplex circuit associated with said line, a relay, a normally inoperative operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operating said relay, said simplex circuit having two terminal bridge-sections for bridging the line circuit, each bridge consisting of a resistance conductor, to the mid-point of which the simplex circuit is connected, means for automatically connecting and disconnecting said terminals across the line, a plurality of circuits, and a progressively movable switch associated with said circuits and control by said relay to extend a connection from said line to any one of said circuits. a

47. In a telephone system, a line, a simplex circuit associated with said line, a relay, a normally inoperative operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operating said relay, said simplex circuit having two terminal bridgo-sections eleotromagnetic means for bridgin said sections across the line circuit, means tor seizing said line, and for rendering said relay responsive to said impulse sender, a plurality of circuits, and a progressively movable switch associated with-said circuits and controlled by said relay to extend a connection from said line to any one of said circuits.

48. In a telephone system, a line, a simplex circuit associated with said line, a relay, a normally inoperative operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for op er ating said relay, said simplex circuit having two terminal bridgesections, electromag netic means for bridging said sections across the line circuit, each bridge consisting of a resistance conductor, to the midpomt of which the simplex circuit is connected, means for seizing said line, and for rendering said line responsive to said impulse sender, a. plurality of circuits, and a progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said circuits.

49. In a telephone system, a line, a simplex circuit associated with said line, a relay, a normally open operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operating said relay, said simplex circuit having two terminal bridge-sections, electromagnetic means for bridging said sections. across the line circuit, a plurality of circuits, and a progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said circuits.

50. In a telephone systen'i a line, a simplex circuit associated with said line, a relay, a. normally open operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operating said relay, said simplex circuit having two terminal bridge-sections, electromagnetic means for bridging said sections across the line circuit, each bridge consisting of a resistance conductor, to the mid-point of which the simplex circuit is connected, a plurality of circuits, and a progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said circuits.

51. In a telephone system, a line, a simplex circuit associated with said line, a relay, a normally open operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operating said relay,"said simplex circuit having two terminal bridge-sections, electromagnetic means for bridging said. sections across the line circuit,'each bridge consisting of a resistance conductor to the midpoint of which the simplex circuit is connected, means for connecting and disconncctin one of said terminals across the line, a pfiirality of circuits, and a progressivelymovable switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said circuits.

In a telephone system, a line, a simplex circuit associated with said line, a relay, a normally open operating circuit for the relay involving said line nd the simplex circuit, an impulse sender, a battery for operating said relay, said simplex circuit having two terminal bridgesections, electromagnetic means for bridging 'said sections acros the line circuit, each bridge consisting of a resistance conductor, to the mid-point of which the simplex circuit is connected, means for automatically connect ing and disconnecting one of said terminals across the line, a plurality of circuits, and a progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said circuits.

53. In a telephone systcm,alinc, a simplex circuit associated with said line, a relay, a normally open operating circuit for the relay involvinp said line and the simplex circuit, an impulse sender, a battery for operating said relay, said simplex circuit having two terminal bridge-sections for bridging the line circuit, each bridge consisting, of a resistance conductor. to the mid-po nt of which the simplex circuit is connected, means for connecting and disconnecting said terminals across the line, a plurality of circuits. and a progressively movable switch asso ciated with said circuits and controlled by said relay to extend connection from said line to any one of said circuits.

54. In a telephone system, a line, a simplex circuit associated with said line, a we lay, a normally open operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operating said relay, said simplex circuit having two terminal bridge-sections for bridging the line circuit, each bridge consisting f a resistance conductonto the midpoint of which the simplex circuit is conhected, means for automatically connecting and disconnecting said terminals across the line, a plurality of circuits, and a progressively movable switch associated with said circuits and'controlled by said relay to extend a connection from said line to any one of said circuits,

55. In a telephone system, a line, a simplex circuit associated with said line, a relay, a normally open operatlng circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operating said relay, said simplex circuit having two terminal bridge-sections, electromagnetic means for bridging said sections across the line circuit, means for seizing said line, and for closing said operating circuit to render said relay responsive to said impuls render, a plurality of circuits, and a progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to 1 any one of said circuits.

at In a telephone system, a line. a simplex circuit associated with said line, a relay. a normally open operating circuit for the relay involving said line and the simpleX circuit. an impulse sender, a battery for operating said relay, said simplex circuit having two terminal bridge-sections, electroinagnetic means for bridging said sections across the line. circuit, each bridge consisting of a resistance conductor, to the u'iid-point of which the simplex circuit is connected. means for seizing said line, and for clo ing said operating circuit to render Said relay responsive to said impulse sender, plurality of circuits. and a progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said circuits.

5?. in. a telephone. store, a line. a simplex circnit associated with said line, a relay, a inlrmally inoperative operating circuit for the relay involving said line and the sin'iplcx circuit, an impulse sender, a battery for operating said relay, said simplex circuit having two terminal bridge sections for bridging the line circuit, a plurality of circuits, a progrcssivelv movable switch associated with said circuits and controlled by said relay to extend a connection from said line'to any one of said circuits, and release apparatus for restoring the Switch controlled by said rclav.

58. In a telephone ystem, a line, a sink plex circuit associated with said line, a relay, a normally inoperative operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operating said relay, said simplex circuit ha ing two terminal bridgescelions for bridging the line circuit, each bridge consisting of a resistance conductor, to the mid-point of which the simplex circuit is connected, means for connecting nd disconnecting one of said terminals across the lin'e, a plurality f circuits, a progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said circuits, and release apparatus for restoring the switch controlled by said relay.

59. In a telephone system a line, a simplex circuit associated with sa d line, a relay, a normally inoperative operating circuit for tho relay involving said line and the simplex circuit, an impulse gender, a battery for operating said relay, said simplex circuit having two terminal bridge-sections for bridging the line circuit, another relay for controlling an automati Switch, and means controlled by said first relay for substituting said second relay in said operating circuit in place of the first relay to the control of the impulse sender.

60. In a telephone system, a line, a simplex circuit associated with said line, a relay, a normally inoperative operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operating said relay, said simplex circuit having two terminal bridge-sections for bridging the line circuit, each bridge cons ting of a resistance conductor, to the mid-p0int of which the simplex circuit is connected, means for connecting and disconnecting one of said terminals across the line, another relay for controllin an automatic switch, and means controlle d by said first relay for substituting said second relay in said operating circuit in place of the first relay to the control of the impulse sender.

61. In a telephone system, a line, a simplex circuit associated with said line, a. relay, a normally inoperative operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a batter for operating said relay, said simplex circuit having two terminal bridge-sections for bridging the line circuit, a plurality of circuits, a progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said circuits, an automatic switch associated with one of said circuits, another relay for controlling said second switch for further extending connection from said line, and means for substituting said second relay for the first relay to the control of the impulse sender when connection is extended by the first switch.

62. In a telephone system, a line, a simplex=circuit associated with said line, a re lay, a normally inoperative operating circuit for the relay involving said line and the sinnlex circuit, an impulse sender, a, battery or operating said rela ,said simplex circuit having two terminal ridge-sections for bridging the line circuit, each bricl e consisting of a resistance conductor, to the mid-point of which the simplex circuit is connected, means for connecting and disconnecting one of said terminals across the line, a plurality of circuits, a progressively movable switch associated with said circuits and controlled by said relay to extend. it connection from said line to any one of aid circuits, an automatic switch associated with one of said circuits, another relay for controlling said second switch for further extending connection from said line, and

means for substituting said second relay for the first relay to the control of the impulse sender when connection is extended by the first switch.

63. In a telephone system, a line, a simplex circuit associated with said line, a relay, a normally inoperative operating ciredit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operating said relay, said simplex cir cuit having the terminal bridge-sections for bridging the line circuit, a plurality of cir cuits, a progressively movable switch associated with said circuits and controlled by said relay to extend a con ection from said line to any one of said cir tits, an automatic progressively movable switch associated with one of said circuits, a plurality of other circuits associated therewith, a second relay for controlling said last automatic switch, and means for substituting said second relay for the first relay in said operating circuit; to the control of the impulse sender who the connection is extended by the first switch.

64. In a telephone system, a line a simplex circuit associated with said line, a relay, a normally inoperative operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operating said relay, said simplex circuit having two terminal bridge-sections for bridging the line circuit, each bridge consisting of a resistance conductor, to the mid-point of which the simplex circuit is connected, means for connecting and discon necting one of said terminals across the line, a plurality of circuits, a progressively movable switch associated with said circuits and controlled by said relay to extend a connec tion from said line to any one of said cir cuits, an automatic progressively movable switch associated with one of said circuits, a lurality of other circuits associated therewith, a second relay for controlling said last automatic switch, and means for substituting said second relay for the first relay in said operating circuit to the control of the impulse sender when the connection is extended by the first switch.

65. In a telephone system, a line, a simplex circuit associated with said line, a relay, a normally inoperative opcrating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operating said relay, a plurality of circuits, a progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said circuits, an automatic switch associated with one of said circuits, another relay for controlling said second switch for further extending connection from said line, and means for substitilting said second relay for the first. relay to the control of the impulse sender when connection is extended by the first switch, means for completing a talking circuit via said line and said extensions, and a central battery for supplying current for talking thereover.

66. In a telephone system, a line, a simplex circuit associated with said line, a relay, a normally inoperative operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operatin" said relay, said simplex circuit having two terminal bridgesections for bridging the line circuit, a plura/lity of circuits, a progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said circuits, an automatic switch associated with one of said circuits, another relay forlcontrolling said second switch for further extending connection from said line, and means for substituting said second relay for the first relay to the control of the impulse sender when connection is extended by the first switch, means for completing a talking circuit via said line and said extensions, and a central battery for supplying current for talking thereover.

67. In a telephone system, a line, a simplcx circuit associated with said line, a. relay, a normally inoperative operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operating said relay, said simplex circuit having two terminal bridge-sections for bridging the line circuit, each bridge consisting of a resistance conductor, to the midpoint of which the simplex circuit is connected, a plurality of circuits, at progressivcly movable switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said circuits, an automatic switch associated with one of said circuits, another relay for controlling said second switch for further extending connection from said line, and means for substituting said second relay for the first relay to the control of the impulse sender when connection is extended bythc first switch, means for completing a talking circuit via said line and said extensions, and a central battery for supplying current for talking thereover.

68. In a telephone system, a line, a simplex circuit associated with said line, a relay, a normally inoperative operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operating said relay, said simplex circuit having two terminal bridge-sections for bridging the line circuit, each bridge consisting of a resistance conductor, to the midpoint of which the simplex circuit is connected, nrieans for connecting and disconnecting one of said terminals across the line,

. any one of said bridhge consisting of a a plurality of circuits, a progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said circuits, an automatic switch associated with one of said circuits, another relay for con trolling said second switch for further extending connection from said line, and means for substituting said second relay for the first relay to the control of the impulse sender when connection is extended by the first switch, means for completing a talking circuit via said line and said extensions, and a central battery forsupplying current for talking thereover.

69. In a telephone system, a line, a simplex circuit associated with said line, a relay, a normally inoperative operating circuit for the relayinvolving said line and the simplex circuit, an impulse sender, a battery for operating said relay, said simplex circuit having two terminal brid e-sections for bridging the line circuit, eac bridge consisting of a resistance conductor, to the midpoint of which the simplex circuit is connected, means -for automatically connecting and disconnecting one of said terminals across the line, a plurality of progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to circuits, an automatic switch associated with one of said circuits, another relay for controlling said second switch for further extending connection fronisaid line,

and means for substituting said second relay for the first relay to the control of the impulse sender when connection is extended by the first switch, means for completing a talking circuit via said line andsaid extensions, and a central battery for supplying current for talking thereover.

70. In a telephone system, a line, a simplex circuit associated with said line, a reay, a normally inoperative opbratlng circuit for lthe relayi involving slaid ling and the simp ex circu t, u so sen er, a battery for operatihg wi elay, said simplex circuit having twmte inal bridge-sections for bridging'tlilpm resistance conductor, to t e mid-point of which the, simplex circuit is connected,means for connecting and disconnecting said terminals across the line, a plurality of circuits, a progressively movable switch associated with said circuits and controlled by said relayto extend a connection from said line to any one of said circuits, an automatic switch associated with 'one of said circuits, another relay for controlling said second switch for further extending connection from said line, and

means for substituting said second relay forthe first: relay to the control of the impulse sender when connection is extended by the circuits, a

ne circuit, each first switch, means for completing a talking circuit via said line and said extensions, and a central battery for supplying current for talking thcrcover.

71. in a lUlCPIlUllO system, a line, a simplex circuit associated. with said line, a relay, a normally inoperative operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operating said relay, said simplex circuit having two terminal bridge-sections for bridging the line circuit, each bridge consisting of a resistance conductor, to the midpoint of which the simplex circuit is connected, means for automaticall connecting and disconnecting said terminas across the line, a plurality of circuits, a progressively movable switch associated with said circuits and controlled b Said relay to extend a onnection from said line to any one oi. said circuits, an automatic switch associated with. one of said circuits, another relay for controlling said second switch for further extending connection from said line, and means for substituting said second relay for the first relay to the control of the impulse sender when connection. extended by the first switcll,'means for completing a talkin circuit via said line and said extensions, anfa central battery for supplying current for talking thereovcr.

72. In a telephone system, a line, a sim plex circuit associated with said line, a relay, a. normally inoperative operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for o crating said relay, meansfor seizing said line, and for rendering said relay responsive to the impulse sender, a pluralit of circuits, a progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said circuits,an automatic switch associated with one of said circuits, another relay for, controlling said second switch for further extending connection from said line, and means for substituting said second relay for the first relay to \v connection is extended by the first switch, means for completing a talking circuit via said line and said extensions, and a central battery for supplying current for talking thereover.

73. In a telephone system, a line, a simlex circuit associated with said line, a re- .ay, a normally inoperative operating circuit for the relay involving said line and the simplex circuit, an impu se sender, a battery for operating said relay, said simplex circuit having two terminal bridge-sections for bridging the line circuit, means for seizin'g said line, and for rendering said relay responsive to said impulse sender, a plurality of circuits, a progressively movable associated with one of said circuits, another a talking circuit in %5. In a telephone contro switch associated with said circuits and controlled by said relay to extend a conneclion from said line to any one of said circuits, an automatic switch associated with one of said circuits, another relay for controlling said second switch for further extending connection from said line, and means for substituting said second relay for the first relay to the control of the impulse sender when connection is extended by the first switch, means for completing a talking circuit via, said .line and said extensions, and a ce ntral battery for supplying current for talking thereover.

74. In a teiephonc system, a line, a simplex circuit associated with said line, a relay, a normally inoperative operating circuit for the relay involving said line and the simplex circuit, an im ulse sender, a battery for operating said re ay, said simplex circuit having two terminal bridge-sections for bridging the line circuit, each bridge consisting of a resistance conductor, to the midpoint of which the simplex circuit is connected, nians for seizing said line, and for rendering said line responsive to said impulse sender, a plurality of circuits, a progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to an one of said circuits, an automatic switc 1 rela for controlling said second switch for further extendin connection from said line, and means for su stituting said second relay for the first relay to the control of the impulse sender when connection is extended by the first switch, means v-ia said line and said exand a central battery for supplyfor talking thereover.

system, a line, a sim plex circuit associated with said line a relay, a normally open operating circuit for the relay invo ving sai line and the simplex circuit, an impulse sender, a battery for operating said relay, a cuits, a progressively mova le switch associated with said circuits and controlled by said relay to extend a connection from'sai dline to any one of said circuits, an automatic switch associated with one of said circuits, another relay for controlling said second switch for further extending connect on from said line, and means for substituting said sicond relay for the first relay to the of the impulse sender when connection is extended by the. first switch, means for completing a talking circuit via said line and said extensions, and a central battery for supplying current for talking thereover.

76. In a telephone system, a line, a simplex circuit associated with said line, a relay, a normally open operating circuit for tensions,

current for completing lurality of cirterminals across the relay involving said line and the simplex circuit, an impulse sender, abattery for oprating said relay, said simplex circuit havng two tcrmina bridge-sections for bridgmg the line circuit, a plurality of circuits, a. progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said circuits, an automatic switch associated with one of said circuits, another relay for controlling said second switch for further extendin connection from said line, and means for su stituting said second relay for the first relay to the control of the impulse sender when a connection is extended by the first switch, means for completing a talking circuit via' said line and said exten- 510118, and a central battery for supplying current for talking thereover.

77. In a telephone system, a line, a simplex circuit associated with said line, a relay, a normally open operating circuit for the relay in volving said line and the simplex circuit, an impulse sender, a battery for operating said relay, said simplex circuit having two terminal bridgesection for bridging the line circuit, each bridge consisting of a resistance conductor, to the midpoint of which the simplex circuit is connected, a plurality of circuits, a progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said circuits, an automatic switch associated with one of said circuits, another relay for controlling said second switch for further extending connection from said line, and means or substituting said second relay for the first relay to the control of the impulse sender when connection is extendcd'by the first switch, means for completing a talking circuit via said line and said'extensions, and a central battery for supplying current for talking thereover.

78. Ina telephone system, a line, a simlex circuit associated ith said line, a reay, a normally open operatin circuit for the relay involving saidline and the-simplex circuit, an impulse sender, a battery for operatin said relay,- said simplex circuit having two terminal bridge-sections for bridging the line circuits, each bridge consisting of a resistance onductor to the midpint of which the simplex circuit is connecte means for connecting and disconnecting one of said the line, a lurality of circuits, a. progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said circuits, an automatic switch associated with one of said circuits, another relay for controlling said second switch for further extending connection from said line, and means for substituting said second relay for the first relay to the control of the impulse sender when connection is extended by the first switch, means for completing a talking circuit i i?! said line and said extensions, and a central battery for supplying current for talking thereover.

75). In a telephone system, a line, a simpl'cx circuit associated with said line. a relay, a normally open operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operating' said relay, said simplex circuit having, two terminal bridgesections for bridging the line circuit, each bridge consisting of aresistance conductor, to the midpointof which the simplex circuit is connected, means for autmimtically connecting and disconnectint; one of said terminals across the line, a plurality of circuits, a progressively movable witch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said Circuits, an automatic switch associated with one of said circuits, another relay for controlling said second switch for further extending connection from said line, and means for sub stituting said second relay for the first relay to the control of the impulse sender when connection is extended by theffirst switch, means for completing, a talking circuit via said line and said extensions, and a central battery for supplying current for'talking thereover.

80. In a telephone system, a line, a similex circuit associated with said line, a relay, a normall open operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operating said relay, said. simplex circuit having two terminal, bridge-sections for bridging the line circuit, each bridge consisting: of a res tancc conductor, to the. mid-point of which, the simplex circuit is connected, means for connecting and disconnecting said terminals across the line, a plurality of circuits, a prog essively movable switch associated wlth said circuits and controlled by said relay to extend connection from said line to an one of said circuits an automatic" switch associated withpne of said circuits, another relay for *controllingsaid second switch for further extending connection from said line, and means for substituting Said second relay for the first relay to the control of the impulse sender when connec' tion is extended by the first switch, means for completing a talkin circuit via said line and said extensions, and a central battery for supplying current for talking thereover.

81. In a telephone system, a line, a simplex circuit associated with said line, a relay, a normally open operating circuit for the relay involving said line and the simplex circuit. an impulse sender, a battery for opn-ating said relay, said simplex circuit having two terminal bridge-sections for bridging the line circuit, each bridge consisting of a resistance condlilctor, to the mid-point of which the simplex circuit is connected, means for automatically connecting and dis connecting said terminals across the line, a plurality of circuits, a progressively mo\'- able switch associated with said circuits and controlled by said relay to extend a connection from said line to any one of said cireuits, 'an automatic switch associated with one of said circuits, another relay for controlling said second switch for further extending connection from said line, and means for substituting said second relay for the first relay to the control of the impulse sender when connection is extended by the first switch, means for completing a talking circuit via said line and said extensions, and a central battery for supplying current for talking thereover.

82. In a telephone system, a line, a simplex circuit associated with said line, a relay, a normally open operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operating said relay, means for seizing said line,

and for closing said operating circuit to render said relay responsive to said impulse sender, a plurality of circuits, a progressively movable switch associated with said circuits and controlled by said relay to ex tend a connection from said line to any one of said circuits, an automatic switch associated with one of said circuits, another relay for controlling said second switch for further extendin connection from said line, and means for su stituting said second relay for the first relay to the control of the im pulse sender when connection is extended by the first switch, means for completing a talking circuit via said line and said extensions, and a central battery for supplying,

current for talking there/over.

83. In a telephone system, a line, a simplex yircuit associated with said line, a relay, a normally open operating circuit for the relay involving said line and the simplex circuit, an impulse sender, a battery for operating said relay, said simplex circuit having two terminal bridge-sections for bridging the line circuit, means for seizing said line, an for closing said operating circuit to render said relay responsive to said impulse sender, a plurality of circuits, a progressively movable switch associated with said circuits and controlled by said relay to extend a connection from said-line to any one of said circuits, an automatic switch associated with one of said circuits, another relay for controlling said second switch for fur ther extending connection from said line, and means for substituting said second 1' lay for the first relay to the control of the impulse sender when connection is extended by the first switch, means for completing a

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